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In this study, we tested the hypothesis that the Piezo1/Ca 2+ /calpain pathway of the basal forebrain (BF) modulates impaired fear conditioning caused by sleep deprivation. Adult male Wistar rats were subjected to 6 h of total sleep deprivation using the gentle handling protocol. Step-down inhibitory avoidance tests revealed that sleep deprivation induced substantial short- and long-term fear memory impairment in rats, which was accompanied by increased Piezo1 protein expression (P < 0.01) and increased cleavage of full-length tropomyocin receptor kinase B (TrkB-FL) (P < 0.01) in the BF area. Microinjection of the Piezo1 activator Yoda1 into the BF mimicked these sleep deprivation-induced phenomena; TrkB-FL cleavage was increased (P < 0.01) and short- and long-term fear memory was impaired (both P < 0.01) by Yoda1. Inhibition of Piezo1 by GsMTx4 in the BF area reduced TrkB-FL degradation (P < 0.01) and partially reversed short- and long-term fear memory impairments in sleep-deprived rats (both P < 0.01). Inhibition of calpain activation, downstream of Piezo1 signaling, also improved short- and long-term fear memory impairments (P = 0.038, P = 0.011) and reduced TrkB degradation (P < 0.01) in sleep-deprived rats. Moreover, sleep deprivation induced a lower pain threshold than the rest control, which was partly reversed by microinjection of GsMTx4 or PD151746. Neither sleep deprivation nor the abovementioned drugs affected locomotion and sedation. Taken together, these results indicate that BF Piezo1/Ca 2+ /calpain signaling plays a role in sleep deprivation-induced TrkB signaling disruption and fear memory impairments in rats., (Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.)

Objective: We investigated whether Piezo1 could regulate oxygen-glucose deprivation/reoxygenation injury of neurons through Ca 2+ /calpain signaling., Methods: Piezo1 expression in rat brain cortex and PC12 cells were confirmed by immunohistochemistry, immunofluorescence and Western blotting. The effects of Yoda1 and GsMTx4 on OGD/R-induced decrease in cell viability, increase in cell apoptosis and activation of downstreaming Ca 2+ /calpain signaling were investigated. Furthermore, calpain signaling was inhibited by PD151746 to see whether Ca 2+ /calpain signaling participated in the neurotoxic effects of Piezo1 activation., Results: Piezo1 expression was increased in rat cerebral cortex after ischemia/reperfusion and in PC12 cells after OGD/R. Activation of Piezo1 by Yoda1 enhanced OGD/R-induced cell viability inhibition, apoptosis, increase intracellular calcium levels and enhanced calpain activity while GsMTx4 showed the opposite effects. The effects of Piezo1 activation on cell viability and apoptosis were reversed by PD151746., Conclusion: Piezo1 could regulate neuron oxygen-glucose deprivation/reoxygenation injury via activation of Ca 2+ /calpain signaling., (Copyright © 2019. Published by Elsevier Inc.)

Membrane proteins play key roles in many fundamental functions in cells including ATP synthesis, ion and molecule transporter, cell signalling and enzymatic reactions, accounting for ~30% genes of whole genomes. However, the hydrophobic nature of membrane proteins frequently hampers the progress of structure determination. Detergent screening is the critical step in obtaining stable detergent-solubilized membrane proteins and well-diffracting protein crystals. Fluorescence Detection Size Exclusion Chromatography (FSEC) has been developed to monitor the extraction efficiency and monodispersity of membrane proteins in detergent micelles. By tracing the FSEC profiles of GFP-fused membrane proteins, this method significantly enhances the throughput of detergent screening. However, current methods to acquire FSEC profiles require either an in-line fluorescence detector with the SEC equipment or an off-line spectrofluorometer microplate reader. Here, we introduce an alternative method detecting the absorption of GFP (FA-SEC) at 485 nm, thus making this methodology possible on conventional SEC equipment through the in-line absorbance spectrometer. The results demonstrate that absorption is in great correlation with fluorescence of GFP. The comparably weaker absorption signal can be improved by using a longer path-length flow cell. The FA-SEC profiles were congruent with the ones plotted by FSEC, suggesting FA-SEC could be a comparable and economical setup for detergent screening of membrane proteins.

Golgi phosphoprotein 2 (Golph2) is a type II Golgi‑specific membrane protein, which has been found to be overexpressed in hepatocellular carcinoma (HCC) patients. The sensitivity of diagnosis of HCC using Golph2 (76%) was markedly elevated compared with alpha‑fetoprotein (AFP) (70%), and Golph2 is expected to be a novel and effective serum biomarker for the diagnosis of HCC. The aim of this study was to prepare monoclonal antibodies against Golph2 and to establish double-antibody sandwich enzyme-linked immunosorbent assay (s-ELISA), which will be used in diagnostics, therapeutics and as a tool in understanding the role of Golph2 in the pathogenesis of liver diseases and cancer. In this study, fusion protein TRX-Golph2 was expressed and purified using an Escherichia coli system. BALB/c mice were immunized with TRX-Golph2 recombinant protein. The hybridoma technique was used for the production of anti-Golph2 monoclonal antibody. Hybridoma clones were screened using indirect ELISA and anti-Golph2 monoclonal antibody was produced in the ascites of BALB/c mice. The specificity of anti-Golph2 monoclonal antibody was detected by western blot analysis and immunocytochemistry. s-ELISA was established using horseradish peroxidase (HRP)‑labeled anti-Golph2 monoclonal antibody and used to detect the antigen in the serum of HCC patients. As a result, five stable hybridoma cell clones (5C6D5, 5B7F5, 7F5F3, 8A7B4, 8C9E8) producing anti-Golph2 monoclonal antibody were established. The highest titer of anti-Golph2 monoclonal antibody (5C6D5) was 1:51,200. Western blot analysis revealed that anti-Golph2 monoclonal antibody had a high specificity for Golph2 protein. Anti-Golph2 monoclonal antibody was HRP-labeled and the optimal working concentration was found to be 1:500. The levels of antigen in a proportion of HCC patients were shown to be significantly higher compared to those found in healthy controls.

Background: Host genetic variation influences human immunodeficiency virus (HIV) infection and progression to AIDS. Here we used clinically well-characterized subjects from 5 pretreatment HIV/AIDS cohorts for a genome-wide association study to identify gene associations with rate of AIDS progression., Methods: European American HIV seroconverters (n = 755) were interrogated for single-nucleotide polymorphisms (SNPs) (n = 700,022) associated with progression to AIDS 1987 (Cox proportional hazards regression analysis, co-dominant model)., Results: Association with slower progression was observed for SNPs in the gene PARD3B. One of these, rs11884476, reached genome-wide significance (relative hazard = 0.3; P =3. 370 × 10(-9)) after statistical correction for 700,022 SNPs and contributes 4.52% of the overall variance in AIDS progression in this study. Nine of the top-ranked SNPs define a PARD3B haplotype that also displays significant association with progression to AIDS (hazard ratio, 0.3; P = 3.220 × 10(-8)). One of these SNPs, rs10185378, is a predicted exonic splicing enhancer; significant alteration in the expression profile of PARD3B splicing transcripts was observed in B cell lines with alternate rs10185378 genotypes. This SNP was typed in European cohorts of rapid progressors and was found to be protective for AIDS 1993 definition (odds ratio, 0.43, P = .025)., Conclusions: These observations suggest a potential unsuspected pathway of host genetic influence on the dynamics of AIDS progression.

Src homology 3 (SH3) domains mediate intracellular protein-protein interactions through the recognition of proline-rich sequence motifs on cellular proteins. Such protein-protein interactions can activate the protein kinase cascade that mediates MAPK signaling pathway. The human hole gene, hhole, is a 319-amino acid six-transmembrane protein with proline-rich C-terminal motifs and N-terminal ERK binding domains (D-domains). The hhole protein is highly conserved in evolution across different species from elegent, mouse to human. Northern blot analysis indicates that hhole is expressed in heart, liver, skeletal muscle, and pancreas at adult stages and in most of the examined embryonic tissues, especially at a higher level in heart. Using a GFP-labeled hhole protein, we demonstrate that hhole is localized in plasma membrane or proximal region of the membrane. Overexpression of hhole in COS-7 cells strongly inhibited the transcriptional activities of AP-1 and SRE while deletion of the C-terminal proline-rich motifs or the N-terminal ERK binding D-domain motifs reduced the repressive activity of the gene. These results suggest that the hhole protein may interact with SH3-domain proteins or ERKs to mediate signaling pathways/networks that lead to the suppression of AP-1 and SRE.

Soil salinity is an important issue, as most crop plants are low in salt tolerance. Salt tolerance, a complex, multifactorial, and multigenic process, has been known to be a quantitative trait. The identification of the salt stress responsive genes or salt tolerance genes is essential for the breeding programs. Most recent efforts have been focused on the products of structural genes (transport proteins, ion channels, enzymes of solute synthesis) while little attention were paid to the regulatory aspects of these proteins. Since the first aquaporin gene from plants was cloned and functionally expressed in 1993, there has been a growing interest in the molecular biology of MIPs (membrane intrinsic proteins) and their bearing on the biophysics of water flow across plant membranes. In the last decades, studies on Mangroves, a special kind of wood plants, grow in high-salt and flooding conditions have been concentrated almost exclusively on their physiological and ecological characteristics. Kandelia candel, one of the dominant species of mangroves along the Chinese coast, lacks salt glands or salt hairs used for removal of excess salt in other mangroves. This makes K. candel a perfect model to study the molecular mechanism of salt tolerance in mangrove plants. Using cDNA RDA, a cDNA-specific modification of genomic representational difference analysis, a series of salt responsive genes of Kandelia candel were cloned. Among these gene fragments, a 183 bp fragment (termed as SRGKC1) encoding a tonoplast intrinsic protein (TIP) in Kandelia candel (KCTIP1) was identified. Based on the sequence of SRGKC1, two gene specific primers were designed, and the 3' and 5' end of the KCTIP1 gene were obtained using the SMART RACE cDNA Amplification Kit. RACE products were purified from low-melting agarose, and sequenced directly with GSPs as the sequencing primers. A 500-bp fragment corresponding to the 3'end of this gene was obtained using the GSP1 primer, and a 690 bp fragment corresponding to the 5' end of this gene was obtained using the GSP2 primer. Two primers that flank the putative open reading frame (ORF) were designed to obtain the cDNA containing the complete ORF by RACE PCR reaction. The full-length cDNA of KCTIP1, containing a 756 bp open reading frame (ORF), was approximately 1.1 kb; the start codon was located at the nucleotides of 99-101 and stop codon at the nucleotides of 855-857 followed by a poly (A) tail. The KCTIP1 cDNA sequence in this research was released in GenBank with accession number AF521135. Using ExPASy Proteomics tools provided by EMBL, the isoelectric point and MWt of KCTIP1 are estimated as 5.77 and 26.3 kD respectively. Transmembrane prediction analysis revealed the deduced KCTIP1 protein sequence contains six transmembrane regions at amino acid residues of 20 - 42, 57 - 79, 86 - 108, 113 - 135, 142 - 164 and 217 - 239. Two highly conserved asparagine-proline-alanine (NPA) motifs were located at 85 - 87 and 199 - 201 amino acid residues respectively. KCTIP1 is also predicted to contain the Cys residue (Cys 118) that are shown to confer Hg-sensitivity in Arabidopsis gamma-TIP and delta-TIP. Similarity analysis showed that KCTIP1 shared 77% - 79% amino acid sequence identity with the TIPs from Vitis berlandieri, Brassica oleracea and Arabidopsis thaliana. Expression analyses indicated that KCTIP1 had different expression among species of Mangroves. Expressions of KCTIP1 in Kandelia candel, Rhizophora apoculata and Ceriops tagal were suppressed by salt, and were insensitive to salt stress in unknown species of Mangroves. Previous studied showed that salt conditions might result in large and rapid changes in extracellular water potential and serious disturbance to the cytoplasm. In order to compensate for this imbalance, the relative contribution of water channels to flow across the root could thus vary. K. candel is a species that is native to intertial zone of tropical and subtropical coast and is well-adapted to salt conditions. The coordinated down-regulation of aquaporins in this plant may decrease membrane water permeability and thus increase the cellular water conserva- tion during periods of salt stress. The results reported here are consistent with the postulated roles for tonoplast water channels in regulating the hydraulic permeability of the vacuolar membranes and in adjusting the water homeostasis of the protoplasm under various physiological conditions. The identification of KCTIP1 as one of salt-responsive genes implies that intracellular osmotic equilibration is a part of salt-tolerant mechanisms in Mangroves.

Background: We identified an autophagy-inducing areca nut (AN) ingredient (AIAI) in the 30-100 kDa fraction of AN extract (ANE 30-100K). This study was to analyze the role of endocytosis in ANE 30-100K-induced autophagy.Methods: We used benzyl alcohol, dynasore, and shRNA of clathrin and dynamin to assess whether ANE 30-100K-induced cytotoxicity and accumulation of microtubule-associated protein 1 light chain 3 (LC3)-II were affected in oral (OECM-1) and esophageal (CE81T/VGH) carcinoma cells.Results: Both benzyl alcohol and dynasore effectively reduced ANE 30-100K-induced cytotoxicity and LC3-II accumulation in OECM-1 and CE81T/VGH cells. Downregulated protein expression of both clathrin and dynamin by their shRNA also significantly attenuated ANE 30-100K-induced elevation of LC3-II levels in CE81T/VGH cells.Conclusions: These results indicate that AIAI may be engulfed by cells through clathrin-mediated endocytosis, which promotes the execution of the following autophagy program. [ABSTRACT FROM AUTHOR]

The neuroprotective role of Buyang Huanwu decoction (BYHWD) in focal ischemia is associated with decreasing glutamate concentration. However, the mechanisms are not fully understood. The present study aimed to explore whether glutamate transporter-1 (GLT-1) and glutamine synthetase (GS) participated in the decreased level of glutamate and whether pituitary adenylate cyclase-activating polypeptide-38 (PACAP-38) was involved in this process. BYHWD was found to significantly upregulate the expression of GLT-1 and GS in the hippocampal CA1 area compared to the ischemia group, with the difference on day 3 being most significant. BYHWD increased the level of PACAP-38, and PACAP-(6-38) (PACAP receptor antagonist) significantly attenuated the effect of BYHWD on GLT-1 and GS, suggesting that PACAP-38 was involved in the upregulation of GLT-1 and GS induced by BYHWD. In addition, as GLT-1 and GS are mainly located in astrocytes, the changes of astrocytes were detected by glial fibrillary acidic protein (GFAP; an astrocytic marker) immunostaining. The results showed that BYHWD inhibited the expression of GFAP compared with the ischemia group, however, co-administration with PACAP-(6-38), which inhibited the effect of BYHWD on GLT-1 and GS in astrocytes, attenuated this effect, indicating that astrocytes participated in the protective role of BYHWD following focal ischemia. These results provided the evidence for the first time that not only neurons but also astrocytes contribute to the protective role of BYHWD, which opposes previous studies and may be a starting point for traditional medicine. [ABSTRACT FROM AUTHOR]

The topology of helix-bundle membrane proteins provides low-resolution structural information with regard to the number and orientation of membrane-spanning helices, as well as the sidedness of intra/extra-cellular domains. In the past decades, several strategies have been developed to experimentally determine the topology of membrane proteins. However, generally, these methods are labour-intensive, time-consuming and difficult to implement for quantitative analysis. Here, we report a novel approach, site-directed alkylation detected by in-gel fluorescence (SDAF), which monitors the fluorescent band shift caused by alkylation of the EGFP-fused target membrane protein bearing one single introduced cysteine. In-gel fluorescence provides a unique readout of target membrane proteins with EGFP fusion from non-purified samples, revealing a distinct 5 kDa shift on SDS-PAGE gel due to conjugation with mPEG-MAL-5K. Using the structurally characterised bile acid transporter ASBTNM as an example, we demonstrate that SDAF generates a topology map consistent with the crystal structure. The efficiency of mPEG-MAL-5K modification at each introduced cysteine can easily be quantified and analysed, providing a useful tool for probing the solvent accessibility at a specific position of the target membrane protein. [ABSTRACT FROM AUTHOR]

Import and assembly of mitochondrial proteins depend on a complex interplay of proteinaceous translocation machineries. The role of lipids in this process has been studied only marginally and so far no direct role for a specific lipid in mitochondrial protein biogenesis has been shown. Here we analyzed a potential role of phosphatidic acid (PA) in biogenesis of mitochondrial proteins in Saccharomyces cerevisiae. In vivo remodeling of the mitochondrial lipid composition by lithocholic acid treatment or by ablation of the lipid transport protein Ups1, both leading to an increase of mitochondrial PA levels, specifically stimulated the biogenesis of the outer membrane protein Ugo1, a component of the mitochondrial fusion machinery. We reconstituted the import and assembly pathway of Ugo1 in protein-free liposomes, mimicking the outer membrane phospholipid composition, and found a direct dependency of Ugo1 biogenesis on PA. Thus, PA represents the first lipid that is directly involved in the biogenesis pathway of a mitochondrial membrane protein. [ABSTRACT FROM AUTHOR]

Newly assembled dengue viruses (DENV) undergo maturation to become infectious particles. The maturation process involves major rearrangement of virus surface premembrane (prM) and envelope (E) proteins. The prM-E complexes on immature viruses are first assembled as trimeric spikes in the neutral pH environment of the endoplasmic reticulum. When the virus is transported to the low pH environment of the exosomes, these spikes rearrange into dimeric structures, which lie parallel to the virus lipid envelope. The proteins involved in driving this process are unknown. Previous cryoelectron microscopy studies of the mature DENV showed that the prM-stem region (residues 111-131) is membrane-associated and may interact with the E proteins. Here we investigated the prM-stem region in modulating the virus maturation process. The binding of the prM-stem region to the E protein was shown to increase significantly at low pH compared with neutral pH in ELISAs and surface plasmon resonance studies. In addition, the affinity of the prM-stem region for the liposome, as measured by fluorescence correlation spectroscopy, was also increased when pH is lowered. These results suggest that the prM-stem region forms a tight association with the virus membrane and attracts the associated E protein in the low pH environment of exosomes. This will lead to the surface protein rearrangement observed during maturation. [ABSTRACT FROM AUTHOR]

Recognition of lipids by proteins is important for their targeting and activation in many signaling pathways, but the mechanisms that regulate such interactions are largely unknown. Here, we found that binding of proteins to the ubiquitous signaling lipid phosphatidic acid (PA) depended on intracellular pH and the protonation state of its phosphate headgroup. In yeast, a rapid decrease in intracellular pH in response to glucose starvation regulated binding of PA to a transcription factor, Opil, that coordinately repressed phospholipid metabolic genes. This enabled coupling of membrane biogenesis to nutrient availability. [ABSTRACT FROM AUTHOR]