Search

Chronic exposure to manganese compounds leads to accumulation of the manganese in the basal ganglia and hippocampus. High levels of manganese in these structures lead to oxidative stress, neuroinflammation, imbalance of brain neurotransmitters, and hyperactivation of calpains mediating neurotoxicity and causing motor and cognitive impairment. The purpose of this work was to study the effect of excess manganese chloride intake on rats' spatial memory and on dopamine-β-hydroxylase (DβH) activity under conditions of calpain activity suppression. Rats were divided into 3 groups of 10 animals each. Group 1 received MnCl2 (30 days, 5 mg/kg/day, intranasally), group 2 received MnCl2 (30 days, 5 mg/kg/day, intranasally) and calpain inhibitor Cast (184–210) (30 days, 5 µg/kg/day, intranasally), and group 3 received sterile saline (30 days in a volume of 20 μl, intranasally). The spatial working memory was assessed using Morris water maze test. DβH activity was determined by HPLC. We have shown that in response to excessive intake of MnCl2, there was a development of cognitive impairments in rats, which was accompanied by a decrease in DβH activity in the hippocampus. The severity of cognitive impairment was reduced by inhibiting the activity of m-calpain. The protective effect of calpain inhibitors was achieved not through an effect on DβH activity. Thus, the development of therapeutic regimens for the treatment of manganism using dopaminomimetics and/or by inhibiting calpains, must be performed taking into account the manganese-induced decrease of DβH activity and the inability to influence this process with calpain inhibitors. [ABSTRACT FROM AUTHOR]

In Chlamydomonas, the directly light‐gated, plasma membrane‐localized cation channels channelrhodopsins ChR1 and ChR2 are the primary photoreceptors for phototaxis. Their targeting and abundance is essential for optimal movement responses. However, our knowledge how Chlamydomonas achieves this is still at its infancy. Here we show that ChR1 internalization occurs via light‐stimulated endocytosis. Prior or during endocytosis ChR1 is modified and forms high molecular mass complexes. These are the solely detectable ChR1 forms in extracellular vesicles and their abundance therein dynamically changes upon illumination. The ChR1‐containing extracellular vesicles are secreted via the plasma membrane and/or the ciliary base. In line with this, ciliogenesis mutants exhibit increased ChR1 degradation rates. Further, we establish involvement of the cysteine protease CEP1, a member of the papain‐type C1A subfamily. ΔCEP1‐knockout strains lack light‐induced ChR1 degradation, whereas ChR2 degradation was unaffected. Low light stimulates CEP1 expression, which is regulated via phototropin, a SPA1 E3 ubiquitin ligase and cyclic AMP. Further, mutant and inhibitor analyses revealed involvement of the small GTPase ARL11 and SUMOylation in ChR1 targeting to the eyespot and cilia. Our study thus defines the degradation pathway of this central photoreceptor of Chlamydomonas and identifies novel elements involved in its homoeostasis and targeting. Summary Statement: How Chlamydomonas targets and controls the level of its main photoreceptor for photomovement responses is largely unknown. Here we show involvement of light‐stimulated endocytosis, cilia, a small GTPase, and a phototropin E3 ubiquitin ligase‐ and cAMP‐controlled cysteine protease in these processes. [ABSTRACT FROM AUTHOR]

Background and Aims Methods Results Interpretation After peripheral nerve stretch injury, most degenerating axons are thought to become disconnected at the time of injury, referred to as primary axotomy. The possibility of secondary axotomy—a delayed and potentially reversible form of disconnection—has not been evaluated. Here, we investigated secondary axotomy in a rat model of sciatic nerve stretch injury. We also evaluated whether axon sparing and functional improvement results from pharmacological blockade of the sodium‐calcium exchanger 1 (NCX1), which is widely believed to contribute to traumatic axon degeneration but was previously only investigated in vitro.We studied peripheral nerve secondary axotomy in a clinically relevant rat model of sciatic nerve rapid stretch injury with immunolabeling and fluorescence microscopy. The role of NCX1 in secondary axotomy was studied with pharmacological inhibition with SEA0400 and immunolabeling, immunoblot, and behavioral assays.We found that early after injury, many axons remained in‐continuity and that degeneration of axons was delayed, consistent with the occurrence of secondary axotomy. βAPP, a marker of secondary axotomy, accumulated at regions of axon swelling and disconnection, and NCX1 was upregulated and co‐localized to βAPP axonal swellings. Pharmacological blockade of NCX1 after injury reduced calpain activation, proteolytic degradation of neurofilaments, βAPP accumulation, distal axon degeneration, and improved hindlimb function.Our data demonstrate a major role for secondary axotomy in peripheral nerve stretch injury and identify NCX1 as a promising therapeutic target to reduce secondary axotomy and improve functional outcome after nerve injury. [ABSTRACT FROM AUTHOR]

Calpain and PARP-NF-κB signaling are reported to participate in the ischemic brain injury. In this study, it was investigated whether calpain was contributed to the neurovascular unit (NVU) damage through up-regulating PARP-NF-κB signaling during experimental ischemic stroke. Male Sprague-Dawley rats were suffered from 90 min of middle cerebral artery occlusion, followed by reperfusion. The NVU damage was evaluated by the permeability of blood-brain barrier (BBB), the degradation of proteins in extracellular matrix and tight junctions, and ultrastructural changes. The inflammatory response was determined by the expression of inflammatory genes driven by PARP-NF-κB signaling and the activities of myeloperoxidase (MPO). Treatment with MDL 28,170, a calpain inhibitor, improved neurological functions, reduced TUNEL staining index, lessened brain swelling, and decreased infarct volume in ischemic rats. Moreover, it reduced the BBB permeability, enhanced the levels of laminin, collagen IV and occludin, and attenuated the ultrastructural damage of NVU in penumbra and core after induction of ischemia. Meanwhile, it enhanced the levels of cytosolic IκBα, lessened the levels of nuclear PARP and NF-κB p65, reduced the levels of ICAM-1, TNF-α, IL-1β, MMP-9, and MMP-2,and suppressed the activities of MPO in penumbra and core. These data showed that calpain inhibition suppressed PARP-NF-κB signaling-mediated inflammatory response, reduced NVU damage, and protected brain against ischemic stroke, suggesting the involvement of calpain in the NVU damage through up-regulating PARP-NF-κB signaling during brain ischemia. [ABSTRACT FROM AUTHOR]

The inducers of neutrophil extracellular trap (NET) formation are heterogeneous and consequently, there is no specific pathway or signature molecule indispensable for NET formation. But certain events such as histone modification, chromatin decondensation, nuclear envelope breakdown, and NET release are ubiquitous. During NET formation, neutrophils drastically rearrange their cytoplasmic, granular and nuclear content. Yet, the exact mechanism for decoding each step during NET formation still remains elusive. Here, we investigated the mechanism of nuclear envelope breakdown during NET formation. Immunofluorescence microscopic evaluation revealed a gradual disintegration of outer nuclear membrane protein nesprin-1 and alterations in nuclear morphology during NET formation. MALDI-TOF analysis of NETs that had been generated by various inducers detected the accumulation of nesprin-1 fragments. This suggests that nesprin-1 degradation occurs before NET release. In the presence of a calpain-1, inhibitor nesprin-1 degradation was decreased in calcium driven NET formation. Microscopic evaluation confirmed that the disintegration of the lamin B receptor (LBR) and the collapse of the actin cytoskeleton occurs in early and later phases of NET release, respectively. We conclude that the calpain-1 degrades nesprin-1, orchestrates the weakening of the nuclear membrane, contributes to LBR disintegration, and promoting DNA release and finally, NETs formation. [ABSTRACT FROM AUTHOR]

Dairy cattle with high (HM) versus low muscle (LM) reserves as determined by longissimus dorsi muscle depth (LDD) in late gestation exhibit differential muscle mobilization related to subsequent milk production. Moreover, branched-chain volatile fatty acid (BCVFA) supplementation increased blood glucose levels. We hypothesized that differences in HM and LM reflect distinct muscle metabolism and that BCVFA supplementation altered metabolic pathways. At 42 days before expected calving (BEC), Holstein dairy cows were enrolled in a 2 × 2 factorial study of diet and muscle reserves, by assignment to control (CON)- or BCVFA-supplemented diets and LDD of HM (>4.6 cm) or LM (≤4.6 cm) groups: HM-CON (n = 13), HM-BCVFA (n = 10), LM-CON (n = 9), and LM-BCVFA (n = 9). Longisumus dorsi muscle was biopsied at 21 days BEC, total RNA was isolated, and protein-coding gene expression was measured with RNA sequencing. Between HM and LM, 713 genes were differentially expressed and 481 between BCVFA and CON (P < 0.05). Transcriptional signatures indicated differential distribution of type II fibers between groups, with MYH1 greater in LM cattle and MYH2 greater in HM cattle (P < 0.05). Signatures of LM cattle relative to HM cattle indicated greater activation of autophagy, ubiquitin-proteasome, and Ca2+-calpain pathways. HM cattle displayed greater expression of genes that encode extracellular matrix proteins and factors that regulate their proteolysis and turnover. BCVFA modified transcriptomes by increasing expression of genes that regulate fatty acid degradation and flux of carbons into the tricarboxylic acid cycle as acetyl CoA. Molecular signatures support distinct metabolic strategies between LM and HM cattle and that BCVFA supplementation increased substrates for energy generation. NEW & NOTEWORTHY: Muscle biopsies of the longissimus dorsi of prepartum dairy cattle indicate that molecular signatures support distinct metabolic strategies between low- and high-muscle cattle and that branched-chain volatile fatty acid supplementation increased substrates for energy generation. [ABSTRACT FROM AUTHOR]

Amyloid-beta peptide (Aβ) is a neurotoxic constituent of senile plaques in the brains of Alzheimer's disease (AD) patients. The detailed mechanisms by which protein kinase C-delta (PKCδ) contributes to Aβ toxicity is not yet entirely understood. Using fully differentiated primary rat cortical neurons, we found that inhibition of Aβ25-35-induced PKCδ increased cell viability with restoration of neuronal morphology. Using cyclin D1, proliferating cell nuclear antigen (PCNA), and histone H3 phosphorylated at Ser-10 (p-Histone H3) as the respective markers for the G1-, S-, and G2/M-phases, PKCδ inhibition mitigated cell cycle reentry (CCR) and subsequent caspase-3 cleavage induced by both Aβ25-35 and Aβ1-42 in the post-mitotic cortical neurons. Upstream of PKCδ, signal transducers and activators of transcription (STAT)-3 mediated PKCδ induction, CCR, and caspase-3 cleavage upon Aβ exposure. Downstream of PKCδ, aberrant neuronal CCR was triggered by overactivating cyclin-dependent kinase-5 (CDK5) via calpain2-dependent p35 cleavage into p25. Finally, PKCδ and CDK5 also contributed to Aβ25-35 induction of p53-upregulated modulator of apoptosis (PUMA) in cortical neurons. Together, we demonstrated that, in the post-mitotic neurons exposed to Aβs, STAT3-dependent PKCδ expression triggers calpain2-mediated p35 cleavage into p25 to overactivate CDK5, thus leading to aberrant CCR, PUMA induction, caspase-3 cleavage, and ultimately apoptosis. [ABSTRACT FROM AUTHOR]

Coronary heart disease (CHD) is a prevalent cardiac disease that causes over 370,000 deaths annually in the USA. In CHD, occlusion of a coronary artery causes ischemia of the cardiac muscle, which results in myocardial infarction (MI). Junctophilin-2 (JPH2) is a membrane protein that ensures efficient calcium handling and proper excitation-contraction coupling. Studies have identified loss of JPH2 due to calpain-mediated proteolysis as a key pathogenic event in ischemia-induced heart failure (HF). Our findings show that calpain-2-mediated JPH2 cleavage yields increased levels of a C-terminal cleaved peptide (JPH2-CTP) in patients with ischemic cardiomyopathy and mice with experimental MI. We created a novel knock-in mouse model by removing residues 479-SPAGTPPQ-486 to prevent calpain-2-mediated cleavage at this site. Functional and molecular assessment of cardiac function post-MI in cleavage site deletion (CSD) mice showed preserved cardiac contractility and reduced dilation, reduced JPH2-CTP levels, attenuated adverse remodeling, improved T-tubular structure, and normalized SR Ca2+-handling. Adenovirus mediated calpain-2 knockdown in mice exhibited similar findings. Pulldown of CTP followed by proteomic analysis revealed valosin-containing protein (VCP) and BAG family molecular chaperone regulator 3 (BAG3) as novel binding partners of JPH2. Together, our findings suggest that blocking calpain-2-mediated JPH2 cleavage may be a promising new strategy for delaying the development of HF following MI. [Display omitted] • Myocardial infarction causes calpain-dependent cleavage of junctophilin-2 (JPH2). • Deletion of the calpain-2 cleavage site in JPH2 prevents adverse cardiac remodeling. • JPH2-CTP binding to VCP and BAG3 might suppress apoptotic cell death after MI. [ABSTRACT FROM AUTHOR]

Purpose: Resistance training (RT) induces muscle growth at varying rates across RT phases, and evidence suggests that the muscle-molecular responses to training bouts become refined or attenuated in the trained state. This study examined how proteolysis-related biomarkers and extracellular matrix (ECM) remodeling factors respond to a bout of RT in the untrained (UT) and trained (T) state. Methods: Participants (19 women and 19 men) underwent 10 weeks of RT. Biopsies of vastus lateralis were collected before and after (24 h) the first (UT) and last (T) sessions. Vastus lateralis cross-sectional area (CSA) was assessed before and after the experimental period. Results: There were increases in muscle and type II fiber CSAs. In both the UT and T states, calpain activity was upregulated and calpain-1/-2 protein expression was downregulated from Pre to 24 h. Calpain-2 was higher in the T state. Proteasome activity and 20S proteasome protein expression were upregulated from Pre to 24 h in both the UT and T. However, proteasome activity levels were lower in the T state. The expression of poly-ubiquitinated proteins was unchanged. MMP activity was downregulated, and MMP-9 protein expression was elevated from Pre to 24 h in UT and T. Although MMP-14 protein expression was acutely unchanged, this marker was lower in T state. TIMP-1 protein levels were reduced Pre to 24 h in UT and T, while TIMP-2 protein levels were unchanged. Conclusion: Our results are the first to show that RT does not attenuate the acute-induced response of proteolysis and ECM remodeling-related biomarkers. [ABSTRACT FROM AUTHOR]

Abstract Oxidative stress plays an essential role in the progression of Alzheimer’s disease (AD), the most common age-related neurodegenerative disorder. Streptozotocin (STZ)-induced abnormal brain insulin signaling and oxidative stress play crucial roles in the progression of Alzheimer’s disease (AD)-like pathology. Peroxiredoxins (Prxs) are associated with protection from neuronal death induced by oxidative stress. However, the molecular mechanisms underlying Prxs on STZ-induced progression of AD in the hippocampal neurons are not yet fully understood. Here, we evaluated whether Peroxiredoxin 1 (Prx1) affects STZ-induced AD-like pathology and cellular toxicity. Prx1 expression was increased by STZ treatment in the hippocampus cell line, HT-22 cells. We evaluated whether Prx1 affects STZ-induced HT-22 cells using overexpression. Prx1 successfully protected the forms of STZ-induced AD-like pathology, such as neuronal apoptosis, synaptic loss, and tau phosphorylation. Moreover, Prx1 suppressed the STZ-induced increase of mitochondrial dysfunction and fragmentation by down-regulating Drp1 phosphorylation and mitochondrial location. Prx1 plays a role in an upstream signal pathway of Drp1 phosphorylation, cyclin-dependent kinase 5 (Cdk5) by inhibiting the STZ-induced conversion of p35 to p25. We found that STZ-induced of intracellular Ca2+ accumulation was an important modulator of AD-like pathology progression by regulating Ca2+-mediated Calpain activation, and Prx1 down-regulated STZ-induced intracellular Ca2+ accumulation and Ca2+-mediated Calpain activation. Finally, we identified that Prx1 antioxidant capacity affected Ca2+/Calpain/Cdk5-mediated AD-like pathology progress. Therefore, these findings demonstrated that Prx1 is a key factor in STZ-induced hippocampal neuronal death through inhibition of Ca2+/Calpain/Cdk5-mediated mitochondrial dysfunction by protecting against oxidative stress.

Studies have highlighted oxidative damage in the inner ear as a critical pathological basis for sensorineural hearing loss, especially the presbycusis. Poly(ADP-ribose) polymerase-1 (PARP1) activation responds to oxidative stress-induced DNA damage with pro-repair and pro-death effects resembling two sides of the same coin. PARP1-related cell death, known as parthanatos, whose underlying mechanisms are attractive research hotspots but remain to be clarified. In this study, we observed that aged rats showed stria vascularis degeneration and oxidative damage, and PARP1-dependent cell death was prominent in age-related cochlear disorganization and dysfunction. Based on oxidative stress model of primary cultured stria marginal cells (MCs), we revealed that upregulated PARP1 and PAR (Poly(ADP-ribose)) polymers are responsible for MCs oxidative death with high mitochondrial permeability transition pore (mPTP) opening and mitochondrial membrane potential (MMP) collapse, while inhibition of PARP1 ameliorated the adverse outcomes. Importantly, the PARylation of apoptosis-inducing factor (AIF) is essential for its conformational change and translocation, which subsequently causes DNA break and cell death. Concretely, the interaction of PAR and truncated AIF (tAIF) is the mainstream in the parthanatos pathway. We also found that the effects of AIF cleavage and release were achieved through calpain activity and mPTP opening, both of which could be regulated by PARP1 via mediation of mitochondria Ca2+ concentration. In conclusion, the PAR-Ca2+-tAIF signaling pathway in parthanatos contributes to the oxidative stress damage observed in MCs. Targeting PAR-Ca2+-tAIF might be a potential therapeutic strategy for the early intervention of presbycusis and other oxidative stress-associated sensorineural deafness. [Display omitted] • Oxidative damage and cochlear stria vascularis degeneration are evident in old rats with age-related hearing loss. • GO-induced oxidative damage in MCs is alleviated after PARP1 inhibition. • PARylation of tAIF is crucial for its release and translocation in PARP1-related cell death. • PAR-Ca2+-tAIF axis is the promising therapeutic target for modulating oxidative stress in age-related hearing loss. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study investigates differences in focal adhesion (FA) morphology and Talin cleavage levels between transformed and non-transformed cell lines. Utilizing fluorescently tagged wild-type Talin and Talin mutants with calpain cleavage site mutations, FA structures were visualized. Mutations in different Talin cleavage sites showed varying impacts on FA morphology and distribution across melanoma cell lines (Meljuso, A375P, A2058) and a non-transformed cell line (HFF). Western blot analysis, ratiometric fluorescence intensity-based measurements, and FRAP experiments revealed higher Talin cleavage levels within FAs of transformed cell lines compared to non-transformed cells. Additionally, growth assays indicated that reducing calpain cleavage levels attenuated transformed cell growth. These findings suggest that Talin cleavage level is crucial for FA morphology and assembly, with higher levels observed in transformed cells, influencing their growth dynamics. [ABSTRACT FROM AUTHOR]

Background: Daphnia galeata is a suitable model organism for investigating predator-induced defense. Genes and pathways exhibiting differential expression between fish kairomone-treated and untreated groups in D. galeata have been identified. However, understanding of the significance of alternative splicing, a crucial process of the regulation of gene expression in eukaryotes, to this mechanism remains limited. This study measured life-history traits and conducted short-read RNA sequencing and long-read isoform sequencing of two Korean D. galeata genotypes (KB1 and KE2) to uncover the genetic mechanism underlying their phenotypic plasticity under predation stress. Results: KB1 exhibited strategies to enhance fertility and decrease body length when exposed to fish kairomones, while KE2 deployed an adaptive strategy to increase body length. Full-length transcriptomes from KB1 and KE2 yielded 65,736 and 57,437 transcripts, respectively, of which 32 differentially expressed transcripts (DETs) were shared under predation stress across both genotypes. Prominent DETs common to both genotypes were related to energy metabolism and the immune system. Additionally, differential alternative splicing (DAS) events were detected in both genotypes in response to fish kairomones. DAS genes shared between both genotypes may indicate their significant role in the post-transcriptional stress response to fish predation. Calpain-3, involved in digestion and nutrient absorption, was identified as a DAS gene in both genotypes when exposed to fish kairomones. In addition, the gene encoding thymosin beta, which is related to growth, was found to be a statistically significant DAS only in KB1, while that encoding ultraspiracle protein, also associated with growth, was only identified in KE2. Moreover, transcripts encoding proteins such as EGF-like domain-containing protein, vitellogenin fused with superoxide dismutase, and others were identified overlapping between DAS events and DETs and potentially elucidating their association with the observed phenotypic variation in each genotype. Conclusions: Our findings highlight the crucial role of alternative splicing in modulating transcriptome landscape under predation stress in D. galeata, emphasizing the requirement for integrating gene expression and splicing analyses in evolutionary adaptation studies. [ABSTRACT FROM AUTHOR]

Oxidative stress plays an essential role in the progression of Alzheimer’s disease (AD), the most common age-related neurodegenerative disorder. Streptozotocin (STZ)-induced abnormal brain insulin signaling and oxidative stress play crucial roles in the progression of Alzheimer’s disease (AD)-like pathology. Peroxiredoxins (Prxs) are associated with protection from neuronal death induced by oxidative stress. However, the molecular mechanisms underlying Prxs on STZ-induced progression of AD in the hippocampal neurons are not yet fully understood. Here, we evaluated whether Peroxiredoxin 1 (Prx1) affects STZ-induced AD-like pathology and cellular toxicity. Prx1 expression was increased by STZ treatment in the hippocampus cell line, HT-22 cells. We evaluated whether Prx1 affects STZ-induced HT-22 cells using overexpression. Prx1 successfully protected the forms of STZ-induced AD-like pathology, such as neuronal apoptosis, synaptic loss, and tau phosphorylation. Moreover, Prx1 suppressed the STZ-induced increase of mitochondrial dysfunction and fragmentation by down-regulating Drp1 phosphorylation and mitochondrial location. Prx1 plays a role in an upstream signal pathway of Drp1 phosphorylation, cyclin-dependent kinase 5 (Cdk5) by inhibiting the STZ-induced conversion of p35 to p25. We found that STZ-induced of intracellular Ca2+ accumulation was an important modulator of AD-like pathology progression by regulating Ca2+-mediated Calpain activation, and Prx1 down-regulated STZ-induced intracellular Ca2+ accumulation and Ca2+-mediated Calpain activation. Finally, we identified that Prx1 antioxidant capacity affected Ca2+/Calpain/Cdk5-mediated AD-like pathology progress. Therefore, these findings demonstrated that Prx1 is a key factor in STZ-induced hippocampal neuronal death through inhibition of Ca2+/Calpain/Cdk5-mediated mitochondrial dysfunction by protecting against oxidative stress. [ABSTRACT FROM AUTHOR]

Meat texture is one of the most important parameters of meat quality and it could be improved by lipid sourced from vegetable oils. This study was undertaken to analyze the changes in meat texture, and in the mRNA expression of calpains (CAPN1 and CAPN3) and calpastatin 2 (CAST2) following diet supplemented with 1% algae (A), 3% sunflower (OS) oil, or 3% soybean oil (SO), using Blanc de Termonde rabbits at different age (12 and 18 weeks). Animals in the control group (C) received feed without additives. Animals were randomly sorted (40 rabbits/each group, balanced for sex). The General Linear Model (GLM) procedure was used to analyze the data and the Tukey–Kramer test was used for multiple comparisons. Our results indicate that the texture of rabbit meat depends on the age and algae, sunflower, and soybean oil supplementation, and diet-age interaction. The influence of the diet on CAPN1, CAPN3, and CAST2 expression depends on the rabbit age. In 12-week-old animals, meat shear force was greater following algae and soybean oil supplementation. Moreover, soybean oil decreased CAPN1, CAPN3, and CAST2, and algae supplement decreased CAST2 genes expression in rabbit muscle. In 18-week-old rabbits, supplementation with sunflower or soybean oil improved meat hardness, chewiness, and shear force. Additionally, sunflower oil increased CAPN1 and decreased CAST2 gene expression in the muscle tissue, providing new information about the molecular mechanism of meat texture in rabbits. [ABSTRACT FROM AUTHOR]

Diabetes mellitus (DM) is a major risk factor for atrial structural remodeling and atrial fibrillation (AF). Calpain activity is hypothesized to promote atrial remodeling and AF. The purpose of this study was to investigate the role of calpain in diabetes-associated AF, fibrosis, and calcium handling dysfunction. DM-associated AF was induced in wild-type (WT) mice and in mice overexpressing the calpain inhibitor calpastatin (CAST-OE) using high-fat diet feeding followed by low-dose streptozotocin injection (75 mg/kg). DM and AF outcomes were assessed by measuring blood glucose levels, fibrosis, and AF susceptibility during transesophageal atrial pacing. Intracellular Ca2+ transients, spontaneous Ca2+ release events, and intracellular T-tubule membranes were measured by in situ confocal microscopy. WT mice with DM had significant hyperglycemia, atrial fibrosis, and AF susceptibility with increased atrial myocyte calpain activity and Ca2+ handling dysfunction relative to control treated animals. CAST-OE mice with DM had a similar level of hyperglycemia as diabetic WT littermates but lacked significant atrial fibrosis and AF susceptibility. DM-induced atrial calpain activity and downregulation of the calpain substrate junctophilin-2 were prevented by CAST-OE. Atrial myocytes of diabetic CAST-OE mice exhibited improved T-tubule membrane organization, Ca2+ handling, and reduced spontaneous Ca2+ release events compared to littermate controls. This study confirmed that DM promotes calpain activation, atrial fibrosis, and AF in mice. CAST-OE effectively inhibits DM-induced calpain activation and reduces atrial remodeling and AF incidence through improved intracellular Ca2+ homeostasis. Our results support calpain inhibition as a potential therapy for preventing and treating AF in DM patients. [ABSTRACT FROM AUTHOR]

Pulmonary hypertension (PAH) is a cardiopulmonary disease in which pulmonary artery pressure continues to rise, leading to right heart failure and death. Otud6b is a member of the ubiquitin family and is involved in cell proliferation, apoptosis and inflammation. The aim of this study was to understand the role and mechanism of Otud6b in PAH. C57BL/6 and Calpain-1 knockout (KO) mice were exposed to a PAH model induced by 10% oxygen. Human pulmonary artery endothelial cells (HPACEs) and human pulmonary artery smooth muscle cells (HPASMCs) were exposed to 3% oxygen to establish an in vitro model. Proteomics was used to determine the role of Otud6b and its relationship to Calpain-1/HIF-1α signaling. The increased expression of Otud6b is associated with the progression of PAH. ROtud6b activates Otud6b, induces HIF-1α activation, increases the production of ET-1 and VEGF, and further aggravates endothelial injury. Reducing Otud6b expression by tracheal infusion of siOtud6b has the opposite effect, improving hemodynamic and cardiac response to PAH, reducing the release of Calpain-1 and HIF-1α, and eliminating the pro-inflammatory and apoptotic effects of Otud6b. At the same time, we also found that blocking Calpain-1 reduced the effect of Otud6b on HIF-1α, and inhibiting HIF-1α reduced the expression of Calpain-1 and Otud6b. Our study shows that increased Otud6b expression during hypoxia promotes the development of PAH models through a positive feedback loop between HIF-1α and Calpain-1. Therefore, we use Otud6b as a biomarker of PAH severity, and regulating Otud6b expression may be an effective target for the treatment of PAH. [ABSTRACT FROM AUTHOR]

Context: Selection for growth rate has received considerable attention in beef cattle but the evidence for an improvement in the efficiency of feed conversion is equivocal. Aim: To examine whether feed efficiency by beef cattle finished in a feedlot had been changed in response to divergence selection for growth rate. Methods: The Angus cattle used came from three lines of cattle selected for over five generations for fast growth rate to yearling age (High-line), slow growth (Low-line), or from an unselected Control-line. Over sequential years, a cohort of steers, then of heifers and then of steers, representative of the lines, were measured for feedlot performance, and carcase- and meat-quality traits. The animals were fed a high-energy feedlot ration and after an adjustment period they underwent a performance test of at least 70 days of duration. After slaughter, muscle samples were taken for subsequent measurement of the components of the endogenous calpain proteolytic enzyme system. Their carcasses underwent a standard chiller assessment and meat samples were taken after 1 day and 14 days (steers) or 17 days (heifers) for objective measurement of tenderness. Key results: Cattle from the High-line grew 48% faster (P < 0.05), and ate 48% more feed (P < 0.05) than did those from the Low-line, but had similar (P > 0.05) feed conversion ratio and residual feed intake. There were no differences between the High-line and Low-line in the visual meat-quality attributes of meat colour, fat colour and marbling, and no differences in the objective measurements of tenderness and connective-tissue toughness. There was no evidence of a selection response in the circulating concentrations of the metabolites and hormones measured, nor in the endogenous calpain proteolytic enzyme system in muscle. Conclusions: The superior growth demonstrated by the High-line cattle over the feedlot test was accompanied by a higher feed intake, with no evidence for an improvement in feed efficiency. Implications: Selection for growth rate is a powerful tool to alter animal performance but the beef industry needs to be cognisant of the proportional increase in feed requirement from breeding bigger animals. Selection for growth rate is a powerful tool to alter beef cattle performance but the evidence for an improvement in feed efficiency is equivocal. This experiment found that selection for faster growth in Angus cattle resulted in heavier cattle that ate more in the feedlot, with no evidence of improvement in feed efficiency. Breeding programs that place emphasis on growth rate need to be cognisant of the proportional increase in feed requirement by bigger animals. [ABSTRACT FROM AUTHOR]

Background: Filaggrin (FLG) is an essential protein that plays a vital role in maintaining skin barrier function and moisture levels, allowing the skin to adapt to dry environments. However, the precise temporal dynamics of FLG metabolism in the human epidermis remain poorly understood, and suitable tools to study these time‐dependent effects are currently lacking. Objective: To investigate the molecular mechanisms and time course of FLG metabolism and skin barrier function under high‐ and low‐humidity conditions, utilizing a reconstructed epidermis model. Methods: EpiSkin specimens cultured under humid or dry conditions for varying durations (2–48 h) were compared by assessing FLG degradation and skin barrier formation using immunofluorescence staining and western blotting. Results: Under conditions of low humidity, the proteolysis of FLG in EpiSkin increased between 4 and 12 h and was accompanied by elevated levels of cysteine–aspartic protease (caspase)‐14. The expression of peptidyl arginine deiminase 1 and calpain 1 also increased at 4 h. However, after 24 h, the expression of these three FLG‐degrading proteins significantly decreased. Conversely, the levels of pyrrolidone‐5‐carboxylic acid and urocanic acid initially decreased at 2 h and then increased between 12 and 24 h. Additionally, the expression of skin barrier proteins, such as FLG, transglutaminase 5, loricrin and zonula occludens‐1, decreased starting from 12 h. Notably, epidermal cell viability and activity were also inhibited. Conclusion: We propose a reliable and ethical model to study the temporal dynamics of FLG metabolism and its role in skin barrier function. Using a commercially reconstructed epidermis to mimic dry skin formation obviates the need for animal and human testing. [ABSTRACT FROM AUTHOR]

The complex regulation of traction forces (TF) produced during cellular migration remains poorly understood. We have previously found that calpain 4 (Capn4), the small non-catalytic subunit of the calpain 1 and 2 proteases, regulates the production of TF independent of the proteolytic activity of the larger subunits. Capn4 was later found to facilitate tyrosine phosphorylation and secretion of the lectin-binding protein galectin-3 (Gal3). In this study, recombinant Gal3 (rGal3) was added to the media-enhanced TF generated by capn4−/− mouse embryonic fibroblasts (MEFs). Extracellular Gal3 also rescued defects in the distribution, morphology, and adhesive strength of focal adhesions present in capn4−/− MEF cells. Surprisingly, extracellular Gal3 does not influence mechanosensing. c-Abl kinase was found to affect Gal3 secretion and the production of TF through phosphorylation of Y107 on Gal3. Our study also suggests that Gal3-mediated regulation of TF occurs through signaling pathways triggered by β1 integrin but not by focal adhesion kinase (FAK) Y397 autophosphorylation. Our findings provide insights into the signaling mechanism by which Capn4 and secreted Gal3 regulate cell migration through the modulation of TF distinctly independent from a mechanosensing mechanism. [ABSTRACT FROM AUTHOR]

Calpain, a key member of the Calpain cysteine protease superfamily, performs limited protein hydrolysis in a calcium-dependent manner. Its activity is tightly regulated due to the potential for non-specific cleavage of various intracellular proteins upon aberrant activation. A thorough review of the literature from 2010 to 2023 reveals 121 references discussing cardiovascular and cerebrovascular diseases. Dysregulation of the Calpain system is associated with various pathological phenomena, including lipid metabolism disorders, inflammation, apoptosis, and excitotoxicity. Although recent studies have revealed the significant role of Calpain in cardiovascular and cerebrovascular diseases, the precise mechanisms remain incompletely understood. Exploring the potential of Calpain inhibition as a therapeutic approach for the treatment of cardiovascular and cerebrovascular diseases may emerge as a compelling area of interest for future calpain research.

Excitotoxicity, a neuronal death process in neurological disorders such as stroke, is initiated by the overstimulation of ionotropic glutamate receptors. Although dysregulation of proteolytic signaling networks is critical for excitotoxicity, the identity of affected proteins and mechanisms by which they induce neuronal cell death remain unclear. To address this, we used quantitative N-terminomics to identify proteins modified by proteolysis in neurons undergoing excitotoxic cell death. We found that most proteolytically processed proteins in excitotoxic neurons are likely substrates of calpains, including key synaptic regulatory proteins such as CRMP2, doublecortin-like kinase I, Src tyrosine kinase and calmodulin-dependent protein kinase IIβ (CaMKIIβ). Critically, calpain-catalyzed proteolytic processing of these proteins generates stable truncated fragments with altered activities that potentially contribute to neuronal death by perturbing synaptic organization and function. Blocking calpain-mediated proteolysis of one of these proteins, Src, protected against neuronal loss in a rat model of neurotoxicity. Extrapolation of our N-terminomic results led to the discovery that CaMKIIα, an isoform of CaMKIIβ, undergoes differential processing in mouse brains under physiological conditions and during ischemic stroke. In summary, by identifying the neuronal proteins undergoing proteolysis during excitotoxicity, our findings offer new insights into excitotoxic neuronal death mechanisms and reveal potential neuroprotective targets for neurological disorders.

Neutrophil-derived proteases are critical to the pathology of many inflammatory lung diseases, both chronic and acute. These abundant enzymes play roles in key neutrophil functions, such as neutrophil extracellular trap formation and reactive oxygen species release. They may also be released, inducing tissue damage and loss of tissue function. Historically, the neutrophil serine proteases (NSPs) have been the main subject of neutrophil protease research. Despite highly promising cell-based and animal model work, clinical trials involving the inhibition of NSPs have shown mixed results in lung disease patients. As such, the cutting edge of neutrophil-derived protease research has shifted to proteases that have had little-to-no research in neutrophils to date. These include the cysteine and serine cathepsins, the metzincins and the calpains, among others. This review aims to outline the previous work carried out on NSPs, including the shortcomings of some of the inhibitor-orientated clinical trials. Our growing understanding of other proteases involved in neutrophil function and neutrophilic lung inflammation will then be discussed. Additionally, the potential of targeting these more obscure neutrophil proteases will be highlighted, as they may represent new targets for inhibitor-based treatments of neutrophil-mediated lung inflammation. [ABSTRACT FROM AUTHOR]

Parkinson's disease (PD), a progressive neurodegenerative disease, has no cure, and current therapies are not effective at halting disease progression. The disease affects mid-brain dopaminergic neurons and, subsequently, the spinal cord, contributing to many debilitating symptoms associated with PD. The GTP-binding protein, Rho, plays a significant role in the cellular pathology of PD. The downstream effector of Rho, Rho-associated kinase (ROCK), plays multiple functions, including microglial activation and induction of inflammatory responses. Activated microglia have been implicated in the pathology of many neurodegenerative diseases, including PD, that initiate inflammatory responses, leading to neuron death. Calpain expression and activity is increased following glial activation, which triggers the Rho-ROCK pathway and induces inflammatory T cell activation and migration as well as mediates toxic α-synuclein (α-syn) aggregation and neuron death, indicating a pivotal role for calpain in the inflammatory and degenerative processes in PD. Increased calpain activity and Rho-ROCK activation may represent a new mechanism for increased oxidative damage in aging. This review will summarize calpain activation and the role of the Rho-ROCK pathway in oxidative stress and α-syn aggregation, their influence on the neurodegenerative process in PD and aging, and possible strategies and research directions for therapeutic intervention. [ABSTRACT FROM AUTHOR]

Our laboratory has shown that calpain‐2 activation in the brain following acute injury is directly related to neuronal damage and the long‐term functional consequences of the injury, while calpain‐1 activation is generally neuroprotective and calpain‐1 deletion exacerbates neuronal injury. We have also shown that a relatively selective calpain‐2 inhibitor, referred to as C2I, enhanced long‐term potentiation and learning and memory, and provided neuroprotection in the controlled cortical impact (CCI) model of traumatic brain injury (TBI) in mice. Using molecular dynamic simulation and Site Identification by Ligand Competitive Saturation (SILCS) software, we generated about 130 analogs of C2I and tested them in a number of in vitro and in vivo assays. These led to the identification of two interesting compounds, NA‐112 and NA‐184. Further analyses indicated that NA‐184, (S)‐2‐(3‐benzylureido)‐N‐((R,S)‐1‐((3‐chloro‐2‐methoxybenzyl)amino)‐1,2‐dioxopentan‐3‐yl)‐4‐methylpentanamide, selectively and dose‐dependent inhibited calpain‐2 activity without evident inhibition of calpain‐1 at the tested concentrations in mouse brain tissues and human cell lines. Like NA‐112, NA‐184 inhibited TBI‐induced calpain‐2 activation and cell death in mice and rats, both male and females. Pharmacokinetic and pharmacodynamic analyses indicated that NA‐184 exhibited properties, including stability in plasma and liver and blood–brain barrier permeability, that make it a good clinical candidate for the treatment of TBI. [ABSTRACT FROM AUTHOR]

Background: Helminth extracellular vesicles (EVs) are known to have a three-way communication function among parasitic helminths, their host and the host-associated microbiota. They are considered biological containers that may carry virulence factors, being therefore appealing as therapeutic and prophylactic target candidates. This study aims to describe and characterise EVs secreted by Sparicotyle chrysophrii (Polyopisthocotyla: Microcotylidae), a blood-feeding gill parasite of gilthead seabream (Sparus aurata), causing significant economic losses in Mediterranean aquaculture. Methods: To identify proteins involved in extracellular vesicle biogenesis, genomic datasets from S. chrysophrii were mined in silico using known protein sequences from Clonorchis spp., Echinococcus spp., Fasciola spp., Fasciolopsis spp., Opisthorchis spp., Paragonimus spp. and Schistosoma spp. The location and ultrastructure of EVs were visualised by transmission electron microscopy after fixing adult S. chrysophrii specimens by high-pressure freezing and freeze substitution. EVs were isolated and purified from adult S. chrysophrii (n = 200) using a newly developed ultracentrifugation-size-exclusion chromatography protocol for Polyopisthocotyla, and EVs were characterised via nanoparticle tracking analysis and tandem mass spectrometry. Results: Fifty-nine proteins involved in EV biogenesis were identified in S. chrysophrii, and EVs compatible with ectosomes were observed in the syncytial layer of the haptoral region lining the clamps. The isolated and purified nanoparticles had a mean size of 251.8 nm and yielded 1.71 × 108 particles · mL−1. The protein composition analysis identified proteins related to peptide hydrolases, GTPases, EF-hand domain proteins, aerobic energy metabolism, anticoagulant/lipid-binding, haem detoxification, iron transport, EV biogenesis-related, vesicle-trafficking and other cytoskeletal-related proteins. Several identified proteins, such as leucyl and alanyl aminopeptidases, calpain, ferritin, dynein light chain, 14–3–3, heat shock protein 70, annexin, tubulin, glutathione S-transferase, superoxide dismutase, enolase and fructose-bisphosphate aldolase, have already been proposed as target candidates for therapeutic or prophylactic purposes. Conclusions: We have unambiguously demonstrated for the first time to our knowledge the secretion of EVs by an ectoparasitic flatworm, inferring their biogenesis machinery at a genomic and transcriptomic level, and by identifying their location and protein composition. The identification of multiple therapeutic targets among EVs' protein repertoire provides opportunities for target-based drug discovery and vaccine development for the first time in Polyopisthocotyla (sensu Monogenea), and in a fish-ectoparasite model. [ABSTRACT FROM AUTHOR]

The N-terminal region of troponin T (TnT) does not bind any protein of the contractile machinery and the role of its hypervariability remains uncertain. In this review we report the evidence of the interaction between TnT and AMP deaminase (AMPD), a regulated zinc enzyme localized on the myofibril. In periods of intense muscular activity, a decrease in the ATP/ADP ratio, together with a decrease in the tissue pH, is the stimulus for the activation of the enzyme that deaminating AMP to IMP and NH3 displaces the myokinase reaction towards the formation of ATP. In skeletal muscle subjected to strong tetanic contractions, a calpain-like proteolytic activity produces the removal in vivo of a 97-residue N-terminal fragment from the enzyme that becomes desensitized towards the inhibition by ATP, leading to an unrestrained production of NH3. When a 95-residue N-terminal fragment is removed from AMPD by trypsin, simulating in vitro the calpain action, rabbit fast TnT or its phosphorylated 50-residue N-terminal peptide binds AMPD restoring the inhibition by ATP. Taking in consideration that the N-terminus of TnT expressed in human as well as rabbit white muscle contains a zinc-binding motif, we suggest that TnT might mimic the regulatory action of the inhibitory N-terminal domain of AMPD due to the presence of a zinc ion connecting the N-terminal and C-terminal regions of the enzyme, indicating that the two proteins might physiologically associate to modulate muscle contraction and ammonia production in fast-twitching muscle under strenuous conditions. [ABSTRACT FROM AUTHOR]

β-catenin is an important regulator of malignant progression. 17β-Estradiol (E2), an important sex hormone in women, promotes the growth and metastasis of triple-negative breast cancer (TNBC). However, whether β-catenin is involved in E2-induced metastasis of TNBC remains unknown. In this study, we show that E2 induces the proliferation, migration, invasion, and metastasis of TNBC cells. E2 induces β-catenin protein expression and nuclear translocation, thereby regulating the expression of target genes such as Cyclin D1 and MMP-9. The inhibition of β-catenin reversed the E2-induced cell malignant behaviors. Additionally, E2 activated Calpain by increasing intracellular Ca2+ levels and reducing calpastatin levels. When Calpain was inhibited, E2 did not induce the proliferation, migration, invasion, or metastasis of TNBC cells. In addition, E2 promoted translocation of YAP into the nucleus by inhibiting its phosphorylation. Calpain inhibition reversed the E2-induced YAP dephosphorylation. Inhibition of YAP transcriptional activity reversed the effects of E2 on the proliferation, migration, invasion, and β-catenin of TNBC cells. In conclusion, we demonstrated that E2 induced metastasis-related behaviors in TNBC cells and this effect was mediated through the Calpain/YAP/β-catenin signaling pathway. [ABSTRACT FROM AUTHOR]

Calpains are cysteine proteases that control cell fate transitions whose loss of function causes severe, pleiotropic phenotypes in eukaryotes. Although mainly considered as modulatory proteases, human calpain targets are directed to the N-end rule degradation pathway. Several such targets are transcription factors, hinting at a gene-regulatory role. Here, we analyze the gene-regulatory networks of the moss Physcomitrium patens and characterize the regulons that are misregulated in mutants of the calpain DEFECTIVE KERNEL1 (DEK1). Predicted cleavage patterns of the regulatory hierarchies in five DEK1-controlled subnetworks are consistent with a pleiotropic and regulatory role during cell fate transitions targeting multiple functions. Network structure suggests DEK1-gated sequential transitions between cell fates in 2D-to-3D development. Our method combines comprehensive phenotyping, transcriptomics and data science to dissect phenotypic traits, and our model explains the protease function as a switch gatekeeping cell fate transitions potentially also beyond plant development. Examination of the cell fate gene-regulatory networks of the moss Physcomitrium patens reveals regulons that exhibit misregulation in mutants for the calpain DEFECTIVE KERNEL1 (DEK1) gene. [ABSTRACT FROM AUTHOR]

Sea cucumber intestines are considered a valuable resource in the sea cucumber processing industry due to their balanced amino acid composition. Studies have reported that peptides rich in glutamate and branched‐chain amino acids have anti‐fatigue properties. However, the function of the sea cucumber intestine in reducing exercise‐induced fatigue remains unclear. In this study, we enzymatically hydrolyzed low molecular weight peptides from sea cucumber intestines (SCIP) and administered SCIP orally to mice to examine its effects on exercise‐induced fatigue using swimming and pole‐climbing exhaustion experiments. The results revealed that supplementation with SCIP significantly prolonged the exhaustion time of swimming in mice, decreased blood lactate and urea nitrogen levels, and increased liver and muscle glycogen levels following a weight‐loaded swimming test. Immunofluorescence analysis indicated a notable increase the proportion of slow‐twitch muscle fiber and a significant decrease the proportion of fast‐twitch muscle fiber following SCIP supplementation. Furthermore, SCIP upregulated mRNA expression levels of Ca2+/Calcineurin upstream and downstream regulators, thereby contributing to the promotion of skeletal muscle fiber type conversion. This study presents the initial evidence establishing SCIP as a potential enhancer of skeletal muscle fatigue resistance, consequently providing a theoretical foundation for the valuable utilization of sea cucumber intestines. [ABSTRACT FROM AUTHOR]

Glioblastoma (GBM) is the most malignant brain tumor, characterized by cell heterogeneity comprising stem cells (GSCs) responsible for aggressiveness. The calpain/calpastatin (calp/cast) proteolytic system is involved in critical physiological processes and cancer progression. In this work we showed the expression profile of hcast 3-25 (a Type III calpastatin variant devoid of inhibitory units) and the members of the system in several patient-derived GSCs exploring the relationship between hcast 3-25 and activation/activity of calpains. Each GSC shows a peculiar calp/cast mRNA and protein expression pattern, and hcast 3-25 is the least expressed. Differentiation promotes upregulation of all the calp/cast system components except hcast 3-25 mRNA, which increased or decreased depending on individual GSC culture. Transfection of hcast 3-25-V5 into two selected GSCs indicated that hcast 3-25 effectively associates with calpains, supporting the digestion of selected calpain targets. Hcast 3-25 possibly affects the stem state promoting a differentiated, less aggressive phenotype.

The glycine transporter GlyT2 plays an important role in glycine-inhibitory neurotransmission of the hindbrain and spinal cord. Its special feature is the extended N-terminus, which contains a large number of potentially phosphorylated serine and threonine residues. Due to its unstructured nature, it is difficult to address the changes introduced by potential phosphorylation. Here, we used relatively simple methods such as calpain sensitivity, Bradford instability, and SDS electrophoretic mobility shift to investigate the effect of multiple phosphomimetic mutations versus neutral mutations on GlyT2N properties. The replacement of several serines or threonines with neutral alanines did not have a significant effect on the studied GlyT2N properties. Replacement of the same residues with phosphomimetic aspartate resulted in significant alterations in calpain cleavage patterns, Bradford instability, and SDS gel protein mobility. Interestingly, a correlation between the relative intensity of the measured effects was observed, indicating that they all reflect similar structural changes introduced by potential phosphorylation in vivo. Results indicate that a potential single or multiple phosphorylation significantly alters the proteomic properties of the glycine transporter GlyT2 N-terminus. Assays can be helpful in the first screening of structurally significant and possibly phosphorylated residues in the N-terminus of GlyT2.

Amyloid-beta peptide (Aβ) is a neurotoxic constituent of senile plaques in the brains of Alzheimer’s disease (AD) patients. The detailed mechanisms by which protein kinase C-delta (PKCδ) contributes to Aβ toxicity is not yet entirely understood. Using fully differentiated primary rat cortical neurons, we found that inhibition of Aβ25-35-induced PKCδ increased cell viability with restoration of neuronal morphology. Using cyclin D1, proliferating cell nuclear antigen (PCNA), and histone H3 phosphorylated at Ser-10 (p-Histone H3) as the respective markers for the G1-, S-, and G2/M-phases, PKCδ inhibition mitigated cell cycle reentry (CCR) and subsequent caspase-3 cleavage induced by both Aβ25-35 and Aβ1-42 in the post-mitotic cortical neurons. Upstream of PKCδ, signal transducers and activators of transcription (STAT)-3 mediated PKCδ induction, CCR, and caspase-3 cleavage upon Aβ exposure. Downstream of PKCδ, aberrant neuronal CCR was triggered by overactivating cyclin-dependent kinase-5 (CDK5) via calpain2-dependent p35 cleavage into p25. Finally, PKCδ and CDK5 also contributed to Aβ25-35 induction of p53-upregulated modulator of apoptosis (PUMA) in cortical neurons. Together, we demonstrated that, in the post-mitotic neurons exposed to Aβs, STAT3-dependent PKCδ expression triggers calpain2-mediated p35 cleavage into p25 to overactivate CDK5, thus leading to aberrant CCR, PUMA induction, caspase-3 cleavage, and ultimately apoptosis.

T cells are crucial for efficient antigen-specific immune responses and thus their migration within the body, to inflamed tissues from circulating blood or to secondary lymphoid organs, plays a very critical role. T cell extravasation in inflamed tissues depends on chemotactic cues and interaction between endothelial adhesion molecules and cellular integrins. A migrating T cell is expected to sense diverse external and membrane-intrinsic mechano-physical cues, but molecular mechanisms of such mechanosensing in cell migration are not established. We explored if the professional mechanosensor Piezo1 plays any role during integrin-dependent chemotaxis of human T cells. We found that deficiency of Piezo1 in human T cells interfered with integrin-dependent cellular motility on ICAM-1-coated surface. Piezo1 recruitment at the leading edge of moving T cells is dependent on and follows focal adhesion formation at the leading edge and local increase in membrane tension upon chemokine receptor activation. Piezo1 recruitment and activation, followed by calcium influx and calpain activation, in turn, are crucial for the integrin LFA1 (CD11a/CD18) recruitment at the leading edge of the chemotactic human T cells. Thus, we find that Piezo1 activation in response to local mechanical cues constitutes a membrane-intrinsic component of the 'outside-in' signaling in human T cells, migrating in response to chemokines, that mediates integrin recruitment to the leading edge. [ABSTRACT FROM AUTHOR]

Remote Ischemic Preconditioning (RIPC) can reduce myocardial ischemia-reperfusion injury, but its mechanism is not clear. In order to explore the mechanism of RIPC in myocardial protection, we collected myocardial specimens during cardiac surgery in children with tetralogy of Fallot for sequencing. Our study found RIPC reduces the expression of the calcium channel subunit cacna2d3, thereby impacting the function of calcium channels. As a result, calcium overload during ischemia-reperfusion is reduced, and the activation of calpain 1 is inhibited. This ultimately leads to a decrease in calpain 1 cleavage of Bax, consequently inhibiting increased mitochondrial permeability-mediated apoptosis. Notably, in both murine and human models of myocardial ischemia-reperfusion injury, RIPC inhibiting the expression of the calcium channel subunit cacna2d3 and the activation of calpain 1, improving cardiac function and histological outcomes. Overall, our findings put forth a proposed mechanism that elucidates how RIPC reduces myocardial ischemia-reperfusion injury, ultimately providing a solid theoretical foundation for the widespread clinic application of RIPC. [Display omitted] • Remote ischemic preconditioning reduces myocardial ischemia-reperfusion injury. • RIPC can reduce calcium overload during myocardial ischemia-reperfusion by decreasing the expression of the calcium channel subunit cacna2d3. • Remote ischemic preconditioning decreased the expression of calpain 1 in myocardial ischemia-reperfusion injury. • Calpain 1 cleavage activates Bax in myocardial ischemia-reperfusion injury, ultimately resulting in mitochondrial damage. [ABSTRACT FROM AUTHOR]

Tight control over transcription factor activity is necessary for a sensible balance between cellular proliferation and differentiation in the embryo and during tissue homeostasis by adult stem cells, but mechanistic details have remained incomplete. The homeodomain transcription factor MEIS2 is an important regulator of neurogenesis in the ventricular-subventricular zone (V-SVZ) adult stem cell niche in mice. We here identify MEIS2 as direct target of the intracellular protease calpain-2 (composed of the catalytic subunit CAPN2 and the regulatory subunit CAPNS1). Phosphorylation at conserved serine and/or threonine residues, or dimerization with PBX1, reduced the sensitivity of MEIS2 towards cleavage by calpain-2. In the adult V-SVZ, calpain-2 activity is high in stem and progenitor cells, but rapidly declines during neuronal differentiation, which is accompanied by increased stability of MEIS2 full-length protein. In accordance with this, blocking calpain-2 activity in stem and progenitor cells, or overexpression of a cleavage-insensitive form of MEIS2, increased the production of neurons, whereas overexpression of a catalytically active CAPN2 reduced it. Collectively, our results support a key role for calpain-2 in controlling the output of adult V-SVZ neural stem and progenitor cells through cleavage of the neuronal fate determinant MEIS2. [ABSTRACT FROM AUTHOR]

In 1984, Gary Lynch and Michel Baudry published in Science a novel biochemical hypothesis for learning and memory, in which they postulated that the calciumdependent protease, calpain, played a critical role in regulating synaptic properties and the distribution of glutamate receptors, thereby participating in memory formation in hippocampus. Over the following 40 years, much work has been done to refine this hypothesis and to provide convincing arguments supporting what was viewed at the time as a simplistic view of synaptic biochemistry. We have now demonstrated that the two major calpain isoforms in the brain, calpain-1 and calpain-2, execute opposite functions in both synaptic plasticity/learning and memory and in neuroprotection/neurodegeneration. Thus, calpain-1 activation is required for triggering long-term potentiation (LTP) of synaptic transmission and learning of episodic memory, while calpain-2 activation limits the magnitude of LTP and the extent of learning. On the other hand, calpain-1 is neuroprotective while calpain-2 is neurodegenerative, and its prolonged activation following various types of brain insults leads to neurodegeneration. The signaling pathways responsible for these functions have been identified and involve local protein synthesis, cytoskeletal regulation, and regulation of glutamate receptors. Human families with mutations in calpain-1 have been reported to have impairment in motor and cognitive functions. Selective calpain-2 inhibitors have been synthesized and clinical studies to test their potential use to treat disorders associated with acute neuronal damage, such as traumatic brain injury, are being planned. This review will illustrate the long and difficult journey to validate a bold hypothesis. [ABSTRACT FROM AUTHOR]

In both excitable and nonexcitable cells, diverse physiological processes are linked to different calcium microdomains within nanoscale junctions that form between the plasma membrane and endo-sarcoplasmic reticula. It is now appreciated that the junctophilin protein family is responsible for establishing, maintaining, and modulating the structure and function of these junctions. We review foundational findings from more than two decades of research that have uncovered how junctophilin-organized ultrastructural domains regulate evolutionarily conserved biological processes. We discuss what is known about the junctophilin family of proteins. Our goal is to summarize the current knowledge of junctophilin domain structure, function, and regulation and to highlight emerging avenues of research that help our understanding of the transcriptional, translational, and post-translational regulation of this gene family and its roles in health and during disease. [ABSTRACT FROM AUTHOR]

Desmoplakin (DSP) is a large (~260 kDa) protein found in the desmosome, the subcellular structure that links the intermediate filament network of one cell to its neighbor. A mutation "hot-spot" within the NH2-terminal of the DSP protein (residues 299–515) is associated with arrhythmogenic cardiomyopathy. In a subset of DSP variants, disease is linked to calpain hypersensitivity. Previous studies show that calpain hypersensitivity can be corrected in vitro through the addition of a bulky residue neighboring the cleavage site, suggesting that physically blocking calpain accessibility is a viable strategy to restore DSP levels. Here, we aim to find drug-like molecules that also block calpain-dependent degradation of DSP. To do this, we screened ~2500 small molecules to identify compounds that specifically rescue DSP protein levels in the presence of proteases. We find that several molecules, including sodium dodecyl sulfate, palmitoylethanolamide, GW0742, salirasib, eprosarten mesylate, and GSK1838705A prevent wildtype and disease-variant-carrying DSP protein degradation in the presence of both trypsin and calpain without altering protease function. Computational screenings did not predict which molecules would protect DSP, likely due to a lack of specific DSP–drug interactions. Molecular dynamic simulations of DSP–drug complexes suggest that some long hydrophobic molecules can bind in a shallow hydrophobic groove that runs alongside the protease cleavage site. Identification of these compounds lays the groundwork for pharmacological treatment for individuals harboring these hypersensitive DSP variants. [ABSTRACT FROM AUTHOR]

Background: Postoperative cognitive dysfunction (POCD) is a common disorder after general anesthesia in elderly patients, the precise mechanisms of which remain unclear. Methods: We investigated the effect of isoflurane with or without dantrolene pretreatment on intracellular calcium concentration ([Ca2+]i), reactive oxygen species (ROS) production, cellular lactate dehydrogenase (LDH) leak, calpain activity, and cognitive function using the Morris water maze test of young (3 months), middle-aged (12–13 months), and aged (24–25 months) C57BL6/J mice. Results: Aged cortical and hippocampal neurons showed chronically elevated [Ca2+]i compared to young neurons. Furthermore, aged hippocampal neurons exhibited higher ROS production, increased LDH leak, and elevated calpain activity. Exposure to isoflurane exacerbated these markers in aged neurons, contributing to increased cognitive deficits in aged mice. Dantrolene pretreatment reduced [Ca2+]i for all age groups and prevented or significantly mitigated the effects of isoflurane on [Ca2+]i, ROS production, LDH leak, and calpain activity in aged neurons. Dantrolene also normalized or improved age-associated cognitive deficits and mitigated the cognitive deficits caused by isoflurane. Conclusions: These findings suggest that isoflurane-induced cytotoxicity and cognitive decline in aging are linked to disruptions in neuronal intracellular processes, highlighting the reduction of [Ca2+]i as a potential therapeutic intervention. [ABSTRACT FROM AUTHOR]

Sterile alpha and toll/interleukin receptor motif-containing 1 (SARM1) is a critical regulator of axon degeneration that acts through hydrolysis of NAD+ following injury. Recent work has defined the mechanisms underlying SARM1's catalytic activity and advanced our understanding of SARM1 function in axons, yet the role of SARM1 signaling in other compartments of neurons is still not well understood. Here, we show in cultured hippocampal neurons that endogenous SARM1 is present in axons, dendrites, and cell bodies and that direct activation of SARM1 by the neurotoxin Vacor causes not just axon degeneration, but degeneration of all neuronal compartments. In contrast to the axon degeneration pathway defined in dorsal root ganglia, SARM1-dependent hippocampal axon degeneration in vitro is not sensitive to inhibition of calpain proteases. Dendrite degeneration downstream of SARM1 in hippocampal neurons is dependent on calpain 2, a calpain protease isotype enriched in dendrites in this cell type. In summary, these data indicate SARM1 plays a critical role in neurodegeneration outside of axons and elucidates divergent pathways leading to degeneration in hippocampal axons and dendrites. [ABSTRACT FROM AUTHOR]

High-pressure and temperature extraction (HPTE) can effectively recover bioactive compounds from olive pomace (OP). HPTE extract obtained by extracting OP with ethanol and water (50:50 v/v) at 180 °C for 90 min demonstrated a pronounced ability to preserve intracellular calcium homeostasis, shielding neurons from the harmful effects induced by N-methyl-d-aspartate (NMDA) receptor (NMDAR) overactivation, such as aberrant calpain activation. In this study, the extraction temperature was changed from 37 to 180 °C, and the extracts were evaluated for their antioxidant potency and ability to preserve crucial intracellular Ca2+-homeostasis necessary for neuronal survival. Additionally, to verify the temperature-induced activity of the extract, further extractions on the exhausted olive pomace were conducted, aiming to identify variations in the quality and quantity of extracted phenolic molecules through HPLC analysis. The results revealed a significant increase in bioactive compounds as a function of temperature variation, reaching 6.31 ± 0.09 mgCAE/mL extract for the extraction performed at 180 °C. Subsequent extraction of the exhausted residues yielded extracts that remained active in preventing calcium-induced cell death. Moreover, despite increased antiradical power, extracts re-treated at 180 °C did not display cell protection activity. Our results indicate that the molecules able to maintain physiological Ca2+-homeostasis in murine cortical neurons in conditions of cytotoxic stimulation of NMDAR are wholly recovered from olive pomace only following extraction performed at 180 °C. [ABSTRACT FROM AUTHOR]

Activation of hypoxia‐inducible factor 1α (HIF1α) contributes to blood‐retinal barrier (BRB) breakdown and pathological neovascularization responsible for vision loss in ischemic retinal diseases. During disease progression, mitochondrial biology is altered to adapt to the ischemic environment created by initial vascular dysfunction, but the mitochondrial adaptive mechanisms, which ultimately contribute to the pathogenesis of ischemic retinopathy, remain incompletely understood. In the present study, it is identified that expression of mitochondrial chaperone tumor necrosis factor receptor‐associated protein 1 (TRAP1) is essential for BRB breakdown and pathologic retinal neovascularization in mouse models mimicking ischemic retinopathies. Genetic Trap1 ablation or treatment with small molecule TRAP1 inhibitors, such as mitoquinone (MitoQ) and SB‐U015, alleviate retinal pathologies via proteolytic HIF1α degradation, which is mediated by opening of the mitochondrial permeability transition pore and activation of calcium‐dependent protease calpain‐1. These findings suggest that TRAP1 can be a promising target for the development of new treatments against ischemic retinopathy, such as retinopathy of prematurity and proliferative diabetic retinopathy. [ABSTRACT FROM AUTHOR]

Epilepsy is a chronic neurological disease that is characterized by spontaneous and recurrent seizures. Regulated cell death is a controlled process and has been shown to be involved in neurodegenerative diseases. Necroptosis is a type of regulated cell death, and its association with epilepsy has been documented. Necroptosis signaling can be divided into two pathways: canonical and non-canonical pathways. Inhibition of caspase-8, dimerization of receptor-interacting protein kinase 1 (RIP1) and RIP3, activation of mixed-lineage kinase domain-like protein (MLKL), movement of MLKL to the plasma membrane, and cell rupture occurred in these pathways. Through literature review, it has been revealed that there is a relationship between seizure, neuroinflammation, and oxidative stress. The seizure activity triggers the activation of various pathways within the central nervous system, including TNF-α/matrix metalloproteases, Neogenin and Calpain/ Jun N-terminal Kinase 1, which result in distinct responses in the brain. These responses involve the activation of neurons and astrocytes, consequently leading to an increase in the expression levels of proteins and genes such as RIP1, RIP3, and MLKL in a time-dependent manner in regions such as the hippocampus (CA1, CA3, dentate gyrus, and hilus), piriform cortex, and amygdala. Furthermore, the imbalance in calcium ions, depletion of adenosine triphosphate, and elevation of extracellular glutamate and potassium within these pathways lead to the progression of necroptosis, a reduction in seizure threshold, and increased susceptibility to epilepsy. Therefore, it is plausible that therapeutic targeting of these pathways could potentially provide a promising approach for managing seizures and epilepsy. [ABSTRACT FROM AUTHOR]

Summary: Fish is susceptible to spoilage for enzymatic and microbial activities during storage, proteolysis of MPs by endogenous proteases played a crucial influence in the early postmortem decomposition of myosin. This study aimed to investigate the impact of stable chlorine dioxide (ClO2) combined with slightly acidic electrolyzed water (SAEW) on myofibrillar proteins (MPs) and endogenous proteases alterations in large yellow croaker (Pseudosciaena crocea) during cold storage. The results of Fourier‐transform infrared spectroscopy (FT‐IR) and intrinsic fluorescence intensity (IFI) showed that the ClO2 + SAEW treatment kept the structural stability of protein in fillets during cold storage. Moreover, ClO2 + SAEW treatment dramatically inhibited protein degradation and oxidation. The results of light microscopy further confirmed the results. Meanwhile, there was a tendency to first increase and then decrease on the activities of calpain and cathepsin B, L. According to the correlation analysis and principal component analysis, the activities of endogenous proteases (cathepsin B, D, L, and calpain) were significant (P < 0.01) positively correlated to myofibrillar fragmentation index and trichloroacetic acid‐soluble peptide, and were significant (P < 0.01) negative correlated with the contents of total sulfhydryl and Ca2+‐ATPase. The endogenous proteases activities and protein deterioration were strongly associated. Therefore, endogenous protease was affected by ClO2 and SAEW, which delayed protein degradation in large yellow croaker, especially ClO2 combined with SAEW treatment. [ABSTRACT FROM AUTHOR]

Excess molybdenum (Mo) is harmful to animals, but its nephrotoxicity has not been comprehensively explained. To appraise the influences of excess Mo on Ca homeostasis and apoptosis via PLC/IP3/IP3R axis, primary duck renal tubular epithelial cells were exposed to 480 μM and 960 μM Mo, and joint of 960 μM Mo and 10 μM 2‐APB or 0.125 μM U‐73122 for 12 h (U‐73122 pretreated for 1 h), respectively. The data revealed that the increment of [Ca2+]c induced by Mo mainly originated from intracellular Ca storage. Mo exposure reduced [Ca2+]ER, elevated [Ca2+]mit, [Ca2+]c, and the expression of Ca homeostasis‐related factors (Calpain, CaN, CRT, GRP94, GRP78 and CaMKII). 2‐APB could effectively reverse subcellular Ca2+ redistribution by inhibiting IP3R, which confirmed that [Ca2+]c overload induced by Mo originated from ER. Additionally, PLC inhibitor U‐73122 remarkably mitigated the change, and dramatically reduced the number of apoptotic cells, the expression of Bak‐1, Bax, cleaved‐Caspase‐3/Caspase‐3, and notably increased the expression of Bcl‐xL, Bcl‐2, and Bcl‐2/Bax ratio. Overall, the results confirmed that the Ca2+ liberation of ER via PLC/IP3/IP3R axis was the main cause of [Ca2+]c overload, and then stimulated apoptosis in duck renal tubular epithelial cells. [ABSTRACT FROM AUTHOR]

Hypoxic-ischemic encephalopathy (HIE) is a complex pathophysiological process with multiple links and factors. It involves the interaction of inflammation, oxidative stress, and glucose metabolism, and results in acute and even long-term brain damage and impairment of brain function. Calpain is a family of Ca2+-dependent cysteine proteases that regulate cellular function. Calpain activation is involved in cerebral ischemic injury, and this involvement is achieved by the interaction among Ca2+, substrates, organelles, and multiple proteases in the neuronal necrosis and apoptosis pathways after cerebral ischemia. Many calpain inhibitors have been developed and tested in the biochemical and biomedical fields. This study reviewed the potential role of calpain in the treatment of HIE and related mechanism, providing new insights for future research on HIE. [ABSTRACT FROM AUTHOR]

Copyright of Revista Colombiana de Ciencia Animal - RECIA is the property of Revista Colombiana de Ciencia Animal - RECIA and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)