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Transfer mitokondria interseluler diduga dapat menjadi mekanisme terapi mesenchymal stem cell (MSC) terhadap berbagai penyakit yang diakibatkan oleh gangguan atau kerusakan pada mitokondria, salah satunya kardiomiopati akibat doxorubicin. Tujuan penelitian ini adalah untuk mengetahui peran transfer mitokondria interseluler sebagai mekanisme protektif MSC. Penelitian ex vivo ini menggunakan jantung tikus neonatus yang diberikan doxorubicin dan MSC dengan metode whole organ culture. Pengukuran ekspresi gen Miro1 digunakan sebagai indikator aktivitas transfer mitokondria interseluler dan ekspresi gen p53 sebagai indikator stres sel. Ekspresi gen p53 pada kelompok yang diberikan doxorubicin 20µM selama 30 menit meningkat singnifikan (p

• Armcx1 is involved in the regulation of mitochondrial transport after traumatic brain injury. • Neuroprotective effect of Armcx1 after traumatic brain injury is associated with Miro1. • Inhibition of Armcx1 expression promotes neuronal apoptosis and behavioral deficits in mice after TBI. Armcx1 is a member of the ARMadillo repeat-Containing protein on the X chromosome (ARMCX) family, which is recognized to have evolutionary conserved roles in regulating mitochondrial transport and dynamics. Previous research has shown that Armcx1 is expressed at higher levels in mice after axotomy and in adult retinal ganglion cells after crush injury, and this protein increases neuronal survival and axonal regeneration. However, its role in traumatic brain injury (TBI) is unclear. Therefore, the aim of this study was to assess the expression of Armcx1 after TBI and to explore possible related mechanisms by which Armcx1 is involved in TBI. We used C57BL/6 male mice to model TBI and evaluated the role of Armcx1 in TBI by transfecting mice with Armcx1 small interfering RNA (siRNA) to inhibit Armcx1 expression 24 h before TBI modeling. Western blotting, immunofluorescence, terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining, Nissl staining, transmission electron microscopy, adenosine triphosphate (ATP) level measurement, neuronal apoptosis analysis, neurological function scoring and the Morris water maze were performed. The results demonstrated that Armcx1 protein expression was elevated after TBI and that the Armcx1 protein was localized in neurons and astroglial cells in cortical tissue surrounding the injury site. In addition, inhibition of Armcx1 expression further led to impaired mitochondrial transport, abnormal morphology, reduced ATP levels, aggravation of neuronal apoptosis and neurological dysfunction, and decrease Miro1 expression. In conclusion, our findings indicate that Armcx1 may exert neuroprotective effects by ameliorating neurological injury after TBI through a mitochondrial transport pathway involving Miro1. [ABSTRACT FROM AUTHOR]

Aims/hypothesis: Insulin resistance is a major pathophysiological defect in type 2 diabetes and obesity. Numerous experimental and clinical studies have provided evidence that sustained lipotoxicity-induced mitophagy deficiency can exacerbate insulin resistance, leading to a vicious cycle between mitophagy dysfunction and insulin resistance, and thereby the onset of type 2 diabetes. Emerging evidence suggests that exosomes (Exos) from M2 macrophages play an essential role in modulating metabolic homeostasis. However, how macrophages are affected by lipotoxicity and the role of lipotoxicity in promoting macrophage activation to the M1 state have not been determined. The objective of this study was to determine whether M1 macrophage-derived Exos polarised by lipopolysaccharide (LPS) + palmitic acid (PA)-induced lipotoxicity contribute to metabolic homeostasis and impact the development of insulin resistance in type 2 diabetes. Methods: Lipotoxicity-polarised macrophage-derived M1 Exos were isolated from bone marrow (C57BL/6J mouse)-derived macrophages treated with LPS+PA. Exos were characterised by transmission electron microscopy, nanoparticle tracking analysis and western blotting. Flow cytometry, H&E staining, quantitative real-time PCR, immunofluorescence, glucose uptake and output assays, confocal microscopy imaging, western blotting, GTTs and ITTs were conducted to investigate tissue inflammation, mitochondrial function and insulin resistance in vitro and in vivo. The roles of miR-27-3p and its target gene Miro1 (also known as Rhot1, encoding mitochondrial rho GTPase 1) and relevant pathways were predicted and assessed in vitro and in vivo using specific miRNA mimic, miRNA inhibitor, miRNA antagomir and siRNA. Results: miR-27-3p was highly expressed in M1 Exos and functioned as a Miro1-inactivating miRNA through the miR-27-3p–Miro1 axis, leading to mitochondria fission rather than fusion as well as mitophagy impairment, resulting in NOD-like receptor 3 inflammatory activation and development of insulin resistance both in vivo and in vitro. Inactivation of miR-27-3p induced by M1 Exos prevented type 2 diabetes development in high-fat-diet-fed mice. Conclusions/interpretation: These findings suggest that the miR-27-3p–Miro1 axis, as a novel regulatory mechanism for mitophagy, could be considered as a new therapeutic target for lipotoxicity-related type 2 diabetes disease development. [ABSTRACT FROM AUTHOR]

Mitochondria are multifaceted organelles necessary for numerous cellular signaling and regulatory processes. Mitochondria are dynamic organelles, trafficked and anchored to subcellular sites depending upon the cellular and tissue requirements. Precise localization of mitochondria to apical and basolateral membranes in lung epithelial cells is important for key mitochondrial processes. Miro1 is an outer mitochondrial membrane GTPase that associates with adapter proteins and microtubule motors to promote intracellular movement of mitochondria. We show that deletion of Miro1 in lung epithelial cells leads to perinuclear clustering of mitochondria. However, the role of Miro1 in epithelial cell response to allergic insults remains unknown. We generated a conditional mouse model to delete Miro1 in Club Cell Secretory Protein (CCSP) positive lung epithelial cells to examine the potential roles of Miro1 and mitochondrial trafficking in the lung epithelial response to the allergen, house dust mite (HDM). Our data show that Miro1 suppresses epithelial induction and maintenance of the inflammatory response to allergen, as Miro1 deletion modestly induces increases in pro-inflammatory signaling, specifically IL-6, IL-33, CCL20 and eotaxin levels, tissue reorganization, and airway hyperresponsiveness. Furthermore, loss of Miro1 in CCSP+ lung epithelial cells blocks resolution of the asthmatic insult. This study further demonstrates the important contribution of mitochondrial dynamic processes to the airway epithelial allergen response and the pathophysiology of allergic asthma.

Miro1, a mitochondrial Rho GTPase1, is a kind of mitochondrial outer membrane protein involved in the regulation of mitochondrial anterograde transport and its subcellular distribution. Mitochondria influence reproductive processes of mammals in some aspects. Mitochondria are important for oocyte maturation, fertilization and embryonic development. The purpose of this study was to evaluate whether Miro1 regulates mouse oocyte maturation by altering mitochondrial homeostasis. We showed that Miro1 was expressed in mouse oocyte at different maturation stages. Miro1 mainly distributed in the cytoplasm and around the spindle during oocyte maturation. Small interference RNA‐mediated Miro1 depletion caused significantly abnormal distribution of mitochondria and endoplasmic reticulum as well as mitochondrial dysfunction, resulting in severely impaired germinal vesicle breakdown (GVBD) of mouse oocytes. For those oocytes which went through GVBD in the Miro1‐depleted group, part of them were inhibited in meiotic prophase I stage with abnormal chromosome arrangement and scattered spindle length. Our results suggest that Miro1 is essential for maintaining the maturation potential of mouse oocyte. [ABSTRACT FROM AUTHOR]

The Rho GTPase Miro1, located at the mitochondrial outer membrane is known to properly distribute mitochondria to synapses, aid calcium buffering and initiate PINK1-Parkin mediated mitophagy. Several heterozygous RHOT1/Miro1 variants were identified in sporadic Parkinson’s disease patients. Miro1 R272Q is located within a calcium binding domain, but the functional outcome of this point mutation and its contribution to the development of disease are unclear. To address this, we introduced a heterozygous RHOT1/Miro1 R272Q point mutation in healthy induced pluripotent stem cells. In dopaminergic neurons, Miro1 R272Q does not affect Miro1 protein levels, CCCP-induced mitophagy, nor mitochondrial movement yet causes the fragmentation of mitochondria with reduction of cristae and ATP5A. Inhibition of the mitochondrial calcium uniporter phenocopied Miro1 R272Q cytosolic calcium response to Thapsigargin in active neurons, a similar effect was observed during the calcium buffering phase in Miro1 knockdown neuroblastoma cells. Altered mitochondrial calcium regulation is associated with reduced mitochondrial respiration and reduced catecholamine neurotransmitter uptake. Synaptic changes are not coupled to dopamine distribution or dopamine transporters but are linked to Miro1 R272Q-related calcium handling via the mitochondria concomitant with defective dopamine regulation at the mitochondrial surface by monoamine oxidase. We conclude that the Miro1 R272Q heterozygous point mutation dampens mitochondrial-calcium regulation and mitochondrial capacity via events at the outer membrane that are sufficient to disrupt dopaminergic function. [ABSTRACT FROM AUTHOR]

The Rho GTPase Miro1, located at the mitochondrial outer membrane is known to properly distribute mitochondria to synapses, aid calcium buffering and initiate PINK1-Parkin mediated mitophagy. Several heterozygous RHOT1/Miro1 variants were identified in sporadic Parkinson’s disease patients. Miro1 R272Q is located within a calcium binding domain, but the functional outcome of this point mutation and its contribution to the development of disease are unclear. To address this, we introduced a heterozygous RHOT1/Miro1 R272Q point mutation in healthy induced pluripotent stem cells. In dopaminergic neurons, Miro1 R272Q does not affect Miro1 protein levels, CCCP-induced mitophagy, nor mitochondrial movement yet causes the fragmentation of mitochondria with reduction of cristae and ATP5A. Inhibition of the mitochondrial calcium uniporter phenocopied Miro1 R272Q cytosolic calcium response to Thapsigargin in active neurons, a similar effect was observed during the calcium buffering phase in Miro1 knockdown neuroblastoma cells. Altered mitochondrial calcium regulation is associated with reduced mitochondrial respiration and reduced catecholamine neurotransmitter uptake. Synaptic changes are not coupled to dopamine distribution or dopamine transporters but are linked to Miro1 R272Q-related calcium handling via the mitochondria concomitant with defective dopamine regulation at the mitochondrial surface by monoamine oxidase. We conclude that the Miro1 R272Q heterozygous point mutation dampens mitochondrial-calcium regulation and mitochondrial capacity via events at the outer membrane that are sufficient to disrupt dopaminergic function.

Mitochondrial quality control is sustained by Miro1 (Rhot1), a calcium-binding membrane-anchored GTPase during mitophagy. The exact mechanism that operates the interaction of Miro1 with mitophagy machinery and their role in cigarette smoke (CS)-induced mitochondrial dysfunction that often results in lung inflammation is unclear. We hypothesized that Miro1 plays an important role in regulating mitophagy machinery and the resulting lung inflammation by CS exposure to mice. The lung epithelial Rhot1fl/fl (WT) and Rhot1CreCC10 mice were exposed to mainstream CS for 3 days (acute) and 4 months (chronic). Acute CS exposure showed a notable increase in the total inflammatory cells, macrophages, and neutrophils that are associated with inflammatory mediators. Chronic exposure showed increased infiltration of neutrophils versus air controls. The effects of acute and chronic CS exposure were augmented in the Rhot1CreCC10 group, indicating that epithelial Miro1 ablation led to the augmentation of inflammatory cell infiltration with alteration in the inflammatory mediators. Thus, Rhot1/Miro1 plays an important role in regulating CS-induced lung inflammatory responses with implications in mitochondrial quality control.

Mitochondria are dynamic organelles that undergo regulated microtubule- and actin-mediated trafficking to meet local energy and metabolic needs. Mitochondrial trafficking may be particularly critical in large cells such as eggs and early embryos where spindle formation and polar body extrusion occur in specific regions of the cytoplasm. To investigate the role of mitochondrial distribution in oocytes we have targeted the mitochondrial membrane protein, MIRO1, which couples mitochondria to the motor protein-TRAK complex. Oocyte-specific deletion of MIRO1 leads to the formation of large aggregates of mitochondria in perinuclear and cortical compartments. Mitochondria remain capable of long-range trafficking during maturation, indicating redundancy in the mechanisms coupling mitochondria to motor proteins. Polar body extrusion in the absence of MIRO1 was reduced by approximately 20%. In MIRO1-deleted zygotes, mitochondria showed increased accumulation around the pronuclei but this did not affect mitochondrial distribution to daughter blastomeres. In vitro development of parthenogenetic embryos was also reduced, although no differences were found in the fertility of oocyte-specific Miro1 KO mice. These findings demonstrate MIRO1 acts as a mitochondrial adaptor, setting mitochondrial distribution in oocytes and early embryos, and disrupting this process compromises in vitro oocyte maturation and embryo development.

Miro1 has emerged as an interesting target to study Parkinson's disease-relevant pathways since it is a target of PINK1 and Parkin. Miro1 is a mitochondrial GTPase with the primary function of facilitating mitochondrial movement, and its knockout in mice is postnatally lethal. Here, we investigated the effect of the artificial RHOT1/Miro1 S156A mutation since it is a putative PINK1 phosphorylation site shown to be involved in Miro1 degradation and mitochondrial arrest during mitophagy. We gene-edited a homozygous phospho-null Miro1 S156A mutation in induced pluripotent stem cells to study the mutation in human dopaminergic neurons. This mutation causes a significant depletion of Miro1 steady-state protein levels and impairs further Miro1 degradation upon CCCP-induced mitophagy. However, mitochondrial mass measured by Tom20 protein levels, as well as mitochondrial area, are not affected in Miro1 S156A neurons. The mitochondria are slightly lengthened, which is in line with their increased turnover. Under basal conditions, we found no discernable effect of the mutation on mitochondrial movement in neurites. Interestingly, the S156A mutation leads to a significant reduction of mitochondrial oxygen consumption, which is accompanied by a depletion of OXPHOS complexes III and V. These effects are not mirrored by Miro1 knockdown in neuroblastoma cells, but they are observed upon differentiation. Undifferentiated Miro1 S156A neural precursor cells do not have decreased Miro1 levels nor OXPHOS complexes, suggesting that the effect of the mutation is tied to development. In mature dopaminergic neurons, the inhibition of Miro1 Ser156 phosphorylation elicits a mild loss of mitochondrial quality involving reduced mitochondrial membrane potential, which is sufficient to induce compensatory events involving OXPHOS. We suggest that the mechanism governing Miro1 steady-state levels depends on differentiation state and metabolic demand, thus underscoring the importance of this pathway in the pathobiology of Parkinson's disease. [ABSTRACT FROM AUTHOR]

The mitochondrial outer membrane (MOM)-anchored GTPase Miro1, is a central player in mitochondrial transport and homeostasis. The dysregulation of Miro1 in amyotrophic lateral sclerosis (ALS) and Parkinson’s disease (PD) suggests that Miro1 may be a potential biomarker or drug target in neuronal disorders. However, the molecular functionality of Miro1 under (patho-) physiological conditions is poorly known. For a more comprehensive understanding of the molecular functions of Miro1, we have developed Miro1-specific nanobodies (Nbs) as novel research tools. We identified seven Nbs that bind either the N- or C-terminal GTPase domain of Miro1 and demonstrate their application as research tools for proteomic and imaging approaches. To visualize the dynamics of Miro1 in real time, we selected intracellularly functional Nbs, which we reformatted into chromobodies (Cbs) for time-lapse imaging of Miro1. By genetic fusion to an Fbox domain, these Nbs were further converted into Miro1-specific degrons and applied for targeted degradation of Miro1 in live cells. In summary, this study presents a collection of novel Nbs that serve as a toolkit for advanced biochemical and intracellular studies and modulations of Miro1, thereby contributing to the understanding of the functional role of Miro1 in disease-derived model systems.

Subcellular mitochondrial positioning in cells is necessary for localized energy and signaling requirements. Mitochondria are strategically trafficked throughout the cytoplasm via the actin cytoskeleton, microtubule motor proteins, and adaptor proteins. Miro1, an outer mitochondrial membrane adaptor protein, is necessary for attachment of mitochondria to microtubule motor proteins for trafficking. Previous work showed when Miro1 is deleted (Miro1 -/- ) from mouse embryonic fibroblasts (MEFs), the mitochondria become sequestered to the perinuclear space, disrupting subcellular energy and reactive oxygen species gradients. Here, we show that Miro1 -/- MEFs grow slower compared to Miro1 +/+ and Miro1 -/- MEFs stably re-expressing the Myc-Miro1 plasmid. Miro1 -/- MEFs have a have a cell cycle defect with decreased percentage of cells in G1 and increased cells in the S phase of the cell cycle. We conducted the first ever RNA sequencing experiment dependent upon Miro1 expression and found differential expression in cell proliferation and migration genes upon deletion of Miro1, including the MAP Kinase signaling pathway. We find that ERK1/2 phosphorylation is elevated both spatially (cytoplasm and nucleus) and temporally following serum stimulation in Miro1 -/- MEFs. We investigated the expression levels and oxidation of the Dual Specificity Phosphatases (DUSP1-6), ERK1/2 target phosphatases. We found no differences in DUSP1-6 expression and oxidation under asynchronous and synchronized cells. Lastly, we evaluated the oxidation status of ERK1/2 and found an increase in ERK1/2 oxidation in the Miro1 -/- MEFs compared to Miro1 +/+ and Myc-Miro1. These data highlight transcriptional control based off Miro1 expression and demonstrate the highly dynamic regulation of ERK1/2 upon deletion of Miro1 that may support the observed cell cycle and proliferation defects.

Mitochondrial Rho GTPases (MIRO1 and MIRO2) are primarily studied for their role as resident mitochondrial anchor proteins that facilitate mitochondria trafficking in neurons. However, it is now appreciated that these proteins have critical roles in cancer. In this review, we focus on examining the role of MIROs in cancer, including expression changes in tumors and the molecular mechanisms by which MIROs impact tumor cell growth, invasion, and metastasis. Additionally, we give an overview of how MIRO's functions in normal cells within the tumor microenvironment can support or inhibit tumor growth and metastasis. Although this is still an emerging field, the current consensus is that the MIROs primarily promote tumor progression of disparate tumor types. As mitochondrial proteins are now being targeted in the clinic, we discuss their potential as novel proteins to target in cancer., Competing Interests: Conflict of interest The authors declare no conflict of interest with the contents of this article., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Mitochondrial quality control is sustained by Miro1 (Rhot1), a calcium-binding membrane-anchored GTPase during mitophagy. The exact mechanism that operates the interaction of Miro1 with mitophagy machinery and their role in cigarette smoke (CS)-induced mitochondrial dysfunction that often results in lung inflammation is unclear. We hypothesized that Miro1 plays an important role in regulating mitophagy machinery and the resulting lung inflammation by CS exposure to mice. The lung epithelial Rhot1fl/fl (WT) and Rhot1CreCC10 mice were exposed to mainstream CS for 3 days (acute) and 4 months (chronic). Acute CS exposure showed a notable increase in the total inflammatory cells, macrophages, and neutrophils that are associated with inflammatory mediators. Chronic exposure showed increased infiltration of neutrophils versus air controls. The effects of acute and chronic CS exposure were augmented in the Rhot1CreCC10 group, indicating that epithelial Miro1 ablation led to the augmentation of inflammatory cell infiltration with alteration in the inflammatory mediators. Thus, Rhot1/Miro1 plays an important role in regulating CS-induced lung inflammatory responses with implications in mitochondrial quality control. [ABSTRACT FROM AUTHOR]

There is a lack of reliable molecular markers for Parkinson’s disease (PD) patients and at-risk individuals. The detection of the pre-symptomatic population of PD will empower more effective clinical intervention to delay or prevent disease onset. We have previously found that the mitochondrial protein Miro1 is resistant to mitochondrial depolarization-induced degradation in fibroblasts from a large number of PD patients and several at-risk individuals. Therefore, Miro1 has the potential to molecularly label PD populations. In order to determine whether Miro1 could serve as a molecular marker for the risk of PD, here we examine the Miro1 response to mitochondrial depolarization by biochemical approaches in induced pluripotent stem cells from a cohort of at-risk individuals. Our results show that the Miro1 phenotype is significantly associated with PD risk. We propose that Miro1 is a promising molecular marker for detecting both PD and at-risk populations. Tracking this Miro1 marker could aid in diagnosis and Miro1-based drug discoveries.

A pathophysiological consequence of both type 1 and 2 diabetes is remodelling of the myocardium leading to the loss of left ventricular pump function and ultimately heart failure (HF). Abnormal cardiac bioenergetics associated with mitochondrial dysfunction occurs in the early stages of HF. Key factors influencing mitochondrial function are the shape, size and organisation of mitochondria within cardiomyocytes, with reports identifying small, fragmented mitochondria in the myocardium of diabetic patients. Cardiac mitochondria are now known to be dynamic organelles (with various functions beyond energy production); however, the mechanisms that underpin their dynamism are complex and links to motility are yet to be fully understood, particularly within the context of HF. This review will consider how the outer mitochondrial membrane protein Miro1 (Rhot1) mediates mitochondrial movement along microtubules via crosstalk with kinesin motors and explore the evidence for molecular level changes in the setting of diabetic cardiomyopathy. As HF and diabetes are recognised inflammatory conditions, with reports of enhanced activation of the NLRP3 inflammasome, we will also consider evidence linking microtubule organisation, inflammation and the association to mitochondrial motility. Diabetes is a global pandemic but with limited treatment options for diabetic cardiomyopathy, therefore we also discuss potential therapeutic approaches to target the mitochondrial-microtubule-inflammatory axis.

There is a lack of reliable molecular markers for Parkinson's disease (PD) patients and at-risk individuals. The detection of the pre-symptomatic population of PD will empower more effective clinical intervention to delay or prevent disease onset. We have previously found that the mitochondrial protein Miro1 is resistant to mitochondrial depolarization-induced degradation in fibroblasts from a large number of PD patients and several at-risk individuals. Therefore, Miro1 has the potential to molecularly label PD populations. In order to determine whether Miro1 could serve as a molecular marker for the risk of PD, here we examine the Miro1 response to mitochondrial depolarization by biochemical approaches in induced pluripotent stem cells from a cohort of at-risk individuals. Our results show that the Miro1 phenotype is significantly associated with PD risk. We propose that Miro1 is a promising molecular marker for detecting both PD and at-risk populations. Tracking this Miro1 marker could aid in diagnosis and Miro1-based drug discoveries. [ABSTRACT FROM AUTHOR]

Intracerebral hemorrhage (ICH) is a primary cause of death and disability in adults worldwide. Secondary brain injury (SBI) induced by ICH can lead to impaired mitochondrial function, which ultimately contributes to apoptosis and necrosis. Mitochondrial Rho GTPase 1 (Miro1) is a key regulator of mitochondrial movement and motor protein binding. Although Miro1 has been demonstrated to be implicated in various types of central nervous system damage, its potential effect on ICH-induced SBI has not been studied in detail. Hence, in the present new study, we explored the effect of Miro1 on SBI in vivo and in vitro. Self-body heart blood was injected into the right basal ganglia of the rat brain in vivo. Meanwhile, our in vitro model of ICH was based on the stimulation of oxygen hemoglobin (OxyHb) to neurons. Then, Miro1 was overexpressed both in the brains of rats after ICH in vivo and in OxyHb-treated cultured neurons in vitro. Miro1 overexpression in vivo reduced several pathological indexes such as brain edema, neurobehavioral impairment, and neuronal death. Immunofluorescent staining in vitro showed that overexpression of Miro1 ameliorated neuronal damage via facilitation of mitochondrial transport and distribution. JC-1 staining indicated that overexpression of Miro1 reduced the collapse of mitochondrial membrane potential and enhanced mitochondrial mass. Additionally, live-dead cellular staining and flow cytometry analysis revealed that Miro1 overexpression in cultured neurons reduced both necrotic and apoptotic rates. In contrast, inhibition of Miro1 expression yielded opposite effects to those of Miro1 overexpression. Above all, the upregulation of Miro1 significantly alleviated pathological symptoms on SBI in vivo and in vitro. [ABSTRACT FROM AUTHOR]

Stroke-induced cerebral ischemia is a major cause of death and disability. The disruption of blood flow results in neuronal and glial cell death leading to brain injury. Reperfusion restores oxygen to the affected tissue, but can also cause damage through an enhanced oxidative stress and inflammatory response. This study examines mitochondrial transfer from MSC to neurons and the role it plays in neuronal preservation after oxidant injury. We observed the transfer of mitochondria from MSC to mouse neurons in vitro following hydrogen peroxide exposure. The observed transfer was dependent on cell-to-cell contact and led to increased neuronal survival and improved metabolism. A number of pro-inflammatory and mitochondrial motility genes were upregulated in neurons after hydrogen peroxide exposure. This included Miro1 and TNFAIP2, linking inflammation and mitochondrial transfer to oxidant injury. Increasing Miro1 expression in MSC improved the metabolic benefit of mitochondrial transfer after neuronal oxidant injury. Decreasing Miro1 expression had the opposite effect, decreasing the metabolic benefit of MSC co-culture. MSC transfer of mitochondria to oxidant-damaged neurons may help improve neuronal preservation and functional recovery after stroke. [ABSTRACT FROM AUTHOR]

The interaction of α-synuclein with mitochondria in both typical and atypical Parkinson's disease is a critical component of degeneration. The mechanism of cell-to-cell propagation of pathological α-synuclein in synucleinopathies is unclear. Intercellular exchange of mitochondria along tunnelling nanotubes has been described in other diseases, such as cancer; however, its role in synucleinopathies is unknown. Pathological α-synuclein species have been demonstrated previously to move from cell to cell via tunnelling nanotubes. This process was further explored using co-culture and monoculture systems to determine if α-synuclein binds to migrating mitochondria within tunnelling nanotubes. Super-resolution analysis via stimulated emission depletion microscopy showed interaction between α-synuclein with the mitochondrial outer membrane and the presence of alpha-synuclein associated with mitochondria in tunnelling nanotubes between 1321N1, differentiated THP-1 and SH-SY5Y cell types. siRNA knockdown of Miro1, a critical protein-bridging mitochondria to the motor adaptor complex, had no effect on mitochondrial density or α-synuclein association with mitochondria in tunnelling nanotubes. The results show that α-synuclein aggregates associate with mitochondria in intercellular tunnelling nanotubes, suggesting that mitochondria-mediated α-synuclein transfer between cells may contribute to cell-to-cell spread of α-synuclein aggregates and disease propagation. [ABSTRACT FROM AUTHOR]

Background: The outer mitochondrial Rho GTPase 1, MIRO1, mediates mitochondrial motility within cells, but implications for vascular smooth muscle cell (VSMC) physiology and its roles invascular diseases, such as neointima formation following vascular injury are widely unknown., Methods: An in vivo model of selective Miro1 deletion in VSMCs was generated, and the animals were subjected to carotid artery ligation. The molecular mechanisms relevant to VSMC proliferation were then explored in explanted VSMCs by imaging mitochondrial positioning and cristae structure and assessing the effects on ATP production, metabolic function and interactions with components of the electron transport chain (ETC)., Results: MIRO1 was robustly expressed in VSMCs within human atherosclerotic plaques and promoted VSMC proliferation and neointima formation in mice by blocking cell-cycle progression at G1/S, mitochondrial positioning, and PDGF-induced ATP production and respiration; overexpression of a MIRO1 mutant lacking the EF hands that are required for mitochondrial mobility did not fully rescue these effects. At the ultrastructural level, Miro1 deletion distorted the mitochondrial cristae and reduced the formation of super complexes and the activity of ETC complex I., Conclusions: Mitochondrial motility is essential for VSMC proliferation and relies on MIRO1. The EF-hands of MIRO1 regulate the intracellular positioning of mitochondria. Additionally, the absence of MIRO1 leads to distorted mitochondrial cristae and reduced ATP generation. Our findings demonstrate that motility is linked to mitochondrial ATP production. We elucidated two unrecognized mechanisms through which MIRO1 influences cell proliferation by modulating mitochondria: first, by managing mitochondrial placement via Ca 2+ -dependent EF hands, and second, by affecting cristae structure and ATP synthesis., Competing Interests: The authors have declared that no conflict of interest exists.

Mitochondria are strategically trafficked throughout the cell by the action of microtubule motors, the actin cytoskeleton and adapter proteins. The intracellular positioning of mitochondria supports subcellular levels of ATP, Ca2+ and reactive oxygen species (ROS, i.e. hydrogen peroxide, H2O2). Previous work from our group showed that deletion of the mitochondrial adapter protein Miro1 leads to perinuclear clustering of mitochondria, leaving the cell periphery devoid of mitochondria which compromises peripheral energy status. Herein, we report that deletion of Miro1 significantly restricts subcellular H2O2 levels to the perinuclear space which directly affects intracellular responses to elevated mitochondrial ROS. Using the genetically encoded H2O2-responsive fluorescent biosensor HyPer7, we show that the highest levels of subcellular H2O2 map to sites of increased mitochondrial density. Deletion of Miro1 or disruption of microtubule dynamics with Taxol significantly reduces peripheral H2O2 levels. Following inhibition of mitochondrial complex 1 with rotenone we observe elevated spikes of H2O2 in the cell periphery and complementary oxidation of mitochondrial peroxiredoxin 3 (PRX3) and cytosolic peroxiredoxin 2 (PRX2). Conversely, in cells lacking Miro1, rotenone did not increase peripheral H2O2 or PRX2 oxidation but rather lead to increased nuclear H2O2 and an elevated DNA-damage response. Lastly, local levels of HyPer7 oxidation correlate with the size and abundance of focal adhesions (FAs) in MEFs and cells lacking Miro1 have significantly smaller focal adhesions and reduced phosphorylation levels of vinculin and p130Cas compared to Miro1+/+ MEFs. Together, we present evidence that the intracellular distribution of mitochondria influences subcellular H2O2 levels and local cellular responses dependent on mitochondrial ROS.

The expected increase in prevalence of Parkinson's disease (PD) as the most common neurodegenerative movement disorder over the next years underscores the need for a better understanding of the underlying molecular pathogenesis. Here, first insights provided by genetics over the last two decades, such as dysfunction of molecular and organellar quality control, are described. The mechanisms involved relate to impaired intracellular calcium homeostasis and mitochondrial dynamics, which are tightly linked to the cross talk between the endoplasmic reticulum (ER) and mitochondria. A number of proteins related to monogenic forms of PD have been mapped to these pathways, i.e., PINK1, Parkin, LRRK2, and α-synuclein. Recently, Miro1 was identified as an important player, as several studies linked Miro1 to mitochondrial quality control by PINK1/Parkin-mediated mitophagy and mitochondrial transport. Moreover, Miro1 is an important regulator of mitochondria-ER contact sites (MERCs), where it acts as a sensor for cytosolic calcium levels. The involvement of Miro1 in the pathogenesis of PD was recently confirmed by genetic evidence based on the first PD patients with heterozygous mutations in RHOT1/Miro1. Patient-based cellular models from RHOT1/Miro1 mutation carriers showed impaired calcium homeostasis, structural alterations of MERCs, and increased mitochondrial clearance. To account for the emerging role of Miro1, we present a comprehensive overview focusing on the role of this protein in PD-related neurodegeneration and highlighting new developments in our understanding of Miro1, which provide new avenues for neuroprotective therapies for PD patients.

The expected increase in prevalence of Parkinson's disease (PD) as the most common neurodegenerative movement disorder over the next years underscores the need for a better understanding of the underlying molecular pathogenesis. Here, first insights provided by genetics over the last two decades, such as dysfunction of molecular and organellar quality control, are described. The mechanisms involved relate to impaired intracellular calcium homeostasis and mitochondrial dynamics, which are tightly linked to the cross talk between the endoplasmic reticulum (ER) and mitochondria. A number of proteins related to monogenic forms of PD have been mapped to these pathways, i.e., PINK1, Parkin, LRRK2, and α-synuclein. Recently, Miro1 was identified as an important player, as several studies linked Miro1 to mitochondrial quality control by PINK1/Parkin-mediated mitophagy and mitochondrial transport. Moreover, Miro1 is an important regulator of mitochondria-ER contact sites (MERCs), where it acts as a sensor for cytosolic calcium levels. The involvement of Miro1 in the pathogenesis of PD was recently confirmed by genetic evidence based on the first PD patients with heterozygous mutations in RHOT1 /Miro1. Patient-based cellular models from RHOT1 /Miro1 mutation carriers showed impaired calcium homeostasis, structural alterations of MERCs, and increased mitochondrial clearance. To account for the emerging role of Miro1, we present a comprehensive overview focusing on the role of this protein in PD-related neurodegeneration and highlighting new developments in our understanding of Miro1, which provide new avenues for neuroprotective therapies for PD patients. [ABSTRACT FROM AUTHOR]

Parkinson's disease (PD) is a debilitating movement disorder, significantly afflicting the aging population. Efforts to develop an effective treatment have been challenged by the lack of understanding of the pathological mechanisms underlying neurodegeneration. We have shown that Miro1, an outer mitochondrial membrane protein, situates at the intersection of the complex genetic and functional network of PD. Removing Miro1 from the surface of damaged mitochondria is a prerequisite for mitochondrial clearance via mitophagy. Parkinson's proteins PINK1, Parkin, and LRRK2 are the molecular helpers to remove Miro1 from dysfunctional mitochondria destined for mitophagy. We have found a delay in clearing Miro1 and initiating mitophagy in postmortem brains and induced pluripotent stem cell-derived neurons from PD patients harboring mutations in LRRK2, PINK1, or Parkin, or from sporadic PD patients with no known mutations. In addition, we have shown that reducing Miro1 by both genetic and pharmacological approaches can correct this Miro1 phenotype and rescue Parkinson's-relevant phenotypes in human neurons and fly PD models. These results suggest that the Miro1 defect may be a common denominator for PD, and compounds that reduce Miro1 promise a new class of drugs to battle PD. We propose to couple this Miro1 phenotype with Miro1-based drug discovery in future therapeutic studies, which could significantly improve the success of clinical trials. © 2020 International Parkinson and Movement Disorder Society. [ABSTRACT FROM AUTHOR]

Cardiac hypertrophy is an adaptive response to manage an excessive cardiac workload and maintain normal cardiac function. However, sustained hypertrophy leads to cardiomyopathy, cardiac failure, and death. Adrenergic receptors play a key role in regulating cardiac function under normal and pathological conditions. Mitochondria are responsible for 90% of ATP production in cardiomyocytes. Mitochondrial function is dynamically regulated by fusion and fission processes. Changes in mitochondrial dynamics and metabolism are central issues in cardiac hypertrophy. Stimulating cardiomyocytes with adrenergic agonists generates hypertrophy and increases mitochondrial fission, which in turn is associated with decreased ATP synthesis. Miro1 is a mitochondrial outer membrane protein involved in mitochondrial dynamics and transport in neurons. The objective of this work was to evaluate whether Miro1 regulates cardiomyocyte hypertrophy through changes in mitochondrial dynamics. In neonatal rat ventricular myocytes, we showed that phenylephrine induced cardiomyocyte hypertrophy and increased Miro1 mRNA and protein levels. Moreover, alpha-adrenergic stimulation provoked a mitochondrial fission pattern in the cardiomyocytes. Miro1 knockdown prevented both the cardiomyocyte hypertrophy and mitochondrial fission pattern. Our results suggest that Miro1 participates in phenylephrine-induced cardiomyocyte hypertrophy through mitochondrial fission. • Phenylephrine increases Miro1 mRNA levels and protein content in neonatal rat ventricular cardiomyocytes. • Miro1 is necessary to induce mitochondrial fission in a model of cardiomyocyte hypertrophy triggered by phenylephrine. • Miro1 regulates cardiomyocyte hypertrophy through changes in mitochondrial dynamics. [ABSTRACT FROM AUTHOR]

• Cigarette smoke extract (CSE) treatment induces mitochondrial dyfunction. • CSE alters OXPHOS and mitochondrial respiration. • CSE causes perinuclear mitochondrial clustering and fragmentation. • Miro1 reduction by CSE affects mitochondrial trafficking and mitophagy. Cigarette smoke (CS) is known to cause mitochondrial dysfunction leading to cellular senescence in lung cells. We determined the mechanism of mitochondrial dysfunction by CS in lung epithelial cells. CS extract (CSE) treatment differentially affected mitochondrial function, such as membrane potential, mitochondrial reactive oxygen species (mtROS) and mitochrondrial mass as analyzed by FACS, and were associated with altered oxidative phosphorylation (OXPHOS) protein levels (Complexes I-IV) in primary lung epithelial cells (SAEC and NHBE), and (complexes I and II) in BEAS2B cells. There were dose- and time-dependent changes in mitochondrial respiration (oxygen consumption rate parameters i.e. maximal respiration, ATP production and spare capacity, measured by the Seahorse analyzer) in control vs. CSE treated BEAS2B and NHBE/DHBE cells. Electron microscopy (EM) analysis revealed perinuclear clustering by localization and increased mitochondrial fragmentation by fragement length analysis. Immunoblot analysis revealed CS-mediated increase in Drp1 and decrease in Mfn2 levels that are involved in mitochondrial fission/fusion process. CSE treatment reduced Miro1 and Pink1 abundance that play a crucial role in the intercellular transfer mechanism and mitophagy process. Overall, these findings highlight the role of Miro1 in context of CS-induced mitochondrial dysfunction in lung epithelial cells that may contribute to the pathogenesis of chronic inflammatory lung diseases. [ABSTRACT FROM AUTHOR]

Aims: The outer mitochondrial membrane protein Miro1 is a crucial player in mitochondrial dynamics and calcium homeostasis. Recent evidence indicated that Miro1 mediates calcium-induced mitochondrial shape transition, which is a prerequisite for the initiation of mitophagy. Moreover, altered Miro1 protein levels have emerged as a shared feature of monogenic and sporadic Parkinson's disease (PD), but, so far, no disease-associated variants in RHOT1 have been identified. Here, we aim to explore the genetic and functional contribution of RHOT1 mutations to PD in patient-derived cellular models. Results: For the first time, we describe heterozygous RHOT1 mutations in two PD patients (het c.815G>A; het c.1348C>T) and identified mitochondrial phenotypes with reduced mitochondrial mass in patient fibroblasts. Both mutations led to decreased endoplasmic reticulum-mitochondrial contact sites and calcium dyshomeostasis. As a consequence, energy metabolism was impaired, which in turn caused increased mitophagy. Innovation and Conclusion: Our study provides functional evidence that ROTH1 is a genetic risk factor for PD, further implicating Miro1 in calcium homeostasis and mitochondrial quality control. [ABSTRACT FROM AUTHOR]

Huntington's disease (HD) is a progressive genetic neurodegenerative disease caused by an abnormal expansion of a cytosine-adenine-guanine trinucleotide repeat in the huntingtin gene. One pathological feature of HD is neuronal loss in the striatum. Despite many efforts, mechanisms underlying neuronal loss in HD striatum remain elusive. It was suggested that the mutant huntingtin protein interacts mitochondrial proteins and causes mitochondrial dysfunction in striatal neurons. However, whether axonal transport of mitochondria is altered in HD striatal neurons remains controversial. Here, we examined axonal transport of single mitochondria labelled with Mito-DsRed2 in cultured striatal neurons of zQ175 knock-in mice (a knock-in mouse model of HD). We observed decreased anterograde axonal transport of proximal mitochondria in HD striatal neurons compared with wild-type (WT) striatal neurons. Decreased anterograde transport in HD striatal neurons was prevented by overexpressing mitochondrial Rho GTPase 1 (Miro1). Our results offer a new insight into mechanisms underlying neuronal loss in the striatum in HD. • Cultured striatal neurons were mainly MSNs that are the most vulnerable neurons in HD. • Anterograde axonal transport of proximal mitochondria was altered in HD striatal neurons. • Overexpressing Miro1 prevented altered mitochondrial transport in HD striatal neurons. [ABSTRACT FROM AUTHOR]

Peroxisomes are ubiquitous, highly dynamic, multifunctional compartments in eukaryotic cells, which perform key roles in cellular lipid metabolism and redox balance. Like other membrane-bound organelles, peroxisomes must move in the cellular landscape to perform localized functions, interact with other organelles and to properly distribute during cell division. However, our current knowledge of peroxisome motility in mammalian cells is still very limited. Recently, three independent studies have identified Miro1 as a regulator of peroxisome motility in mammalian cells. In these studies, the authors show that Miro1 is targeted to peroxisomes in several cell lines, in a process that relies on its interaction with the peroxisomal chaperone Pex19. Interestingly, however, different conclusions are drawn about which Miro1 isoforms are targeted to peroxisomes, how it interacts with Pex19 and most importantly, the type of motility Miro1 is regulating.

The human Miro GTPases (hMiros) have recently emerged as important mediators of mitochondrial transport and may significantly contribute to the development of disorders such as Alzheimer's and schizophrenia. The hMiros represent two highly atypical members of the Ras superfamily, and exhibit several unique features: the presence of a GTPase domain at both the N-terminus and C-terminus, the presence of two calcium-binding EF-hand domains and localisation to the mitochondrial outer membrane. Here, elucidation of Miro GTPase signalling pathway components was achieved through the use of molecular biology, cell culture techniques and proteomics. An investigation of this kind has not been performed previously; we hoped, through these techniques, to enable the profiling and identification of pathways regulated by the human Miro GTPases. The results indicate several novel putative interaction partners for hMiro1 and hMiro2, including numerous proteins previously implicated in neurodegenerative pathways and the development of schizophrenia. Furthermore, we show that the N-terminal GTPase domain appears to fine-tune hMiro signalling, with GTP-bound versions of this domain associated with a diverse range of interaction partners in comparison to corresponding GDP-bound versions. Recent evidences suggest that human Miros participate in host-pathogen interactions with Vibrio Cholerae type III secretion proteins. We have undertaken a bioinformatics investigation to identify novel pathogenic effectors that might interact with Miros. [ABSTRACT FROM AUTHOR]

Ca 2+ flux across the inner mitochondrial membrane (IMM) regulates cellular bioenergetics, intra-cellular cytoplasmic Ca 2+ signals, and various cell death pathways. Ca 2+ entry into the mitochondria occurs due to the highly negative membrane potential (ΔΨ m ) through a selective inward rectifying MCU channel. In addition to being regulated by various mitochondrial matrix resident proteins such as MICUs, MCUb, MCUR1 and EMRE, the channel is transcriptionally regulated by upstream Ca 2+ cascade, post transnational modification and by divalent cations. The mode of regulation either inhibits or enhances MCU channel activity and thus regulates mitochondrial metabolism and cell fate. [ABSTRACT FROM AUTHOR]

Peroxisomes are dynamic organelles which fulfil essential roles in lipid and ROS metabolism. Peroxisome movement and positioning allows interaction with other organelles and is crucial for their cellular function. In mammalian cells, such movement is microtubule‐dependent and mediated by kinesin and dynein motors. The mechanisms of motor recruitment to peroxisomes are largely unknown, as well as the role this plays in peroxisome membrane dynamics and proliferation. Here, using a combination of microscopy, live‐cell imaging analysis and mathematical modelling, we identify a role for Mitochondrial Rho GTPase 1 (MIRO1) as an adaptor for microtubule‐dependent peroxisome motility in mammalian cells. We show that MIRO1 is targeted to peroxisomes and alters their distribution and motility. Using a peroxisome‐targeted MIRO1 fusion protein, we demonstrate that MIRO1‐mediated pulling forces contribute to peroxisome membrane elongation and proliferation in cellular models of peroxisome disease. Our findings reveal a molecular mechanism for establishing peroxisome‐motor protein associations in mammalian cells and provide new insights into peroxisome membrane dynamics in health and disease. [ABSTRACT FROM AUTHOR]

Neurons are high-energy consuming cells, heavily dependent on mitochondria for ATP generation and calcium buffering. These mitochondrial functions are particularly critical at specific cellular sites, where ionic currents impose a large energetic burden, such as at synapses. The highly polarized nature of neurons, with extremely large axoplasm relative to the cell body, requires mitochondria to be efficiently transported along microtubules to reach distant sites. Furthermore, neurons are post-mitotic cells that need to maintain pools of healthy mitochondria throughout their lifespan. Hence, mitochondrial transport and turnover are essential processes for neuronal survival and function. In neurodegenerative diseases, the maintenance of a healthy mitochondrial network is often compromised. Numerous lines of evidence indicate that mitochondrial impairment contributes to neuronal demise in a variety of neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), where degeneration of motor neurons causes a fatal muscle paralysis. Dysfunctional mitochondria accumulate in motor neurons affected by genetic or sporadic forms of ALS, strongly suggesting that the inability to maintain a healthy pool of mitochondria plays a pathophysiological role in the disease. This article critically reviews current hypotheses on mitochondrial involvement in the pathogenesis of ALS, focusing on the alterations of mitochondrial axonal transport and turnover in motor neurons.

Mitochondria function to generate ATP and also play important roles in cellular homeostasis, signaling, apoptosis, autophagy, and metabolism. The loss of mitochondrial function results in cell death and various types of diseases. Therefore, quality control of mitochondria via intraand intercellular pathways is crucial. Intracellular quality control consists of biogenesis, fusion and fission, and degradation of mitochondria in the cell, whereas intercellular quality control involves tunneling nanotubes and extracellular vesicles. In this review, we outline the current knowledge on the intra- and intercellular quality control mechanisms of mitochondria. [ABSTRACT FROM AUTHOR]

Ion transport during neuronal signalling utilizes the majority of the brain's energy supply. Mitochondria are key sites for energy provision through ATP synthesis and play other important roles including calcium buffering. Thus, tightly regulated distribution and function of these organelles throughout the intricate architecture of the neuron is essential for normal synaptic communication. Therefore, delineating mechanisms coordinating mitochondrial transport and function is essential for understanding nervous system physiology and pathology. While aberrant mitochondrial transport and dynamics have long been associated with neurodegenerative disease, they have also more recently been linked to major mental illness including schizophrenia, autism and depression. However, the underlying mechanisms have yet to be elucidated, due to an incomplete understanding of the combinations of genetic and environmental factors contributing to these conditions. Consequently, the DISC1 gene has undergone intense study since its discovery at the site of a balanced chromosomal translocation, segregating with mental illness in a Scottish pedigree. The precise molecular functions of DISC1 remain elusive. Reported functions of DISC1 include regulation of intracellular signalling pathways, neuronal migration and dendritic development. Intriguingly, a role for DISC1 in mitochondrial homeostasis and transport is fast emerging. Therefore, a major function of DISC1 in regulating mitochondrial distribution, ATP synthesis and calcium buffering may be disrupted in psychiatric disease. In this review, we discuss the links between DISC1 and mitochondria, considering both trafficking of these organelles and their function, and how, via these processes, DISC1 may contribute to the regulation of neuronal behavior in normal and psychiatric disease states. [ABSTRACT FROM AUTHOR]

Ca 2+ is a ubiquitous intracellular messenger that controls diverse cellular functions but can become toxic and cause cell death. Selective control of specific targets depends on spatiotemporal patterning of the calcium signal and decoding it by multiple, tunable, and often strategically positioned Ca 2+ -sensing elements. Ca 2+ is detected by specialized motifs on proteins that have been biochemically characterized decades ago. However, the field of Ca 2+ sensing has been reenergized by recent progress in fluorescent technology, genetics, and cryo-EM. These approaches exposed local Ca 2+ -sensing mechanisms inside organelles and at the organellar interfaces, revealed how Ca 2+ binding might work to open some channels, and identified human mutations and disorders linked to a variety of Ca 2+ -sensing proteins. Here we attempt to place these new developments in the context of intracellular calcium homeostasis and signaling. [ABSTRACT FROM AUTHOR]

BACKGROUND: High-intensity exercise can induce the depolymerization and/or degradation of tubulin in the skeletal muscle. According to the close relation with the mitochondria, tubulin may influence mitochondrial movement track and molecular motor, thereby varying the movement and distribution of mitochondria. OBJECTIVE: To observe the effect of high-intensity exercise on α-tubulin, MAP4, Miro1 and mitochondrial ultrastructures, analyze their sequential changes and further explore whether tubular depolymerization regulates the movement and distribution of mitochondria via Miro1. METHODS: Fifty-six Sprague-Dawley rats were divided into control (n=8) and exercise (n=48) groups. The rats in the exercise group ran on the treadmill ( -16°, 20 m/minute) for 90 minutes, and the soleus samples were removed immediately, 6, 12, 24, 48 and 72 hours after exercise (n=8 each time point). The expression levels of α-tubulin, MAP4 and Miro1 were detected by western blot assay, and the ultrastructural changes of mitochondria were observed under transmission electron microscope. RESULTS AND CONCLUSION: The expression level of α-tubulin was decreased significantly at 6 and 12 hours after exercise. The expression level of MAP4 was increased significantly at 6, 12, 48 and 72 hours after exercise. The expression level of Miro1 was increased firstly at 6 and 12 hours after exercise, and decreased at 72 hours after exercise. In the control group, the paired mitochondria were arranged on the both sides of Z line, and few appeared in the myolemma. Mitochondria began to accumulate in the myolemma immediately and 6 hours after exercise; the number achieved the peak at 12 hours, reduced at 24 and 48 hours, and returned to normal at 72 hours. These results suggest that high-intensity exercise can induce the depolymerization of microtubules in the skeletal muscle, thus regulating the movement and distribution of mitochondria via Miro1. [ABSTRACT FROM AUTHOR]

Mitochondrial trafficking is influenced by neuronal activity, but it remains unclear how mitochondrial positioning influences neuronal transmission and plasticity. Here, we use live cell imaging with the genetically encoded presynaptically targeted Ca2+ indicator, Sy GCa MP5, to address whether presynaptic Ca2+ responses are altered by mitochondria in synaptic terminals. We find that presynaptic Ca2+ signals, as well as neurotransmitter release, are significantly decreased in terminals containing mitochondria. Moreover, the localisation of mitochondria at presynaptic sites can be altered during long-term activity changes, dependent on the Ca2+-sensing function of the mitochondrial trafficking protein, Miro1. In addition, we find that Miro1-mediated activity-dependent synaptic repositioning of mitochondria allows neurons to homeostatically alter the strength of presynaptic Ca2+ signals in response to prolonged changes in neuronal activity. Our results support a model in which mitochondria are recruited to presynaptic terminals during periods of raised neuronal activity and are involved in rescaling synaptic signals during homeostatic plasticity. [ABSTRACT FROM AUTHOR]

Parkinsonism is a complex neurodegenerative disease that is difficult to differentiate because of its idiopathic and unknown origins. The hereditary parkinsonism known as autosomal recessive-juvenile parkinsonism (AR-JP) is marked by tremors, dyskinesias, dystonic characteristics, and manifestations that improve sleep but do not include dementia. This was caused by deletions and point mutations in PARK2 (chromosome 6q25.2–27). Diminished or unusual sensations (paresthesias), loss of neuron strength both in the CNS and peripheral nerves, and lack of motor coordination are the hallmarks of neuropathy in parkinsonism. The incidence of parkinsonism during oxidative stress and ageing is associated with parkinopathy. Parkinopathy is hypothesized to be triggered by mutation of the parkin (PRKN) gene and loss of normal physiological functions of PRKN proteins, which triggers their pathogenic aggregation due to conformational changes. Two important genes that control mitochondrial health are PRKN and phosphatase and tensin homologue deleted on chromosome 10-induced putative kinase 1 (PINK1). Overexpression of TAR DNA-binding protein-43 (TDP-43) increases the aggregation of insoluble PRKN proteins in OMM. Foreign α-synuclein (ASN) promotes parkinopathy via S-nitrosylation and hence has a neurotoxic effect on dopaminergic nerves. Miro1 (Miro GTPase1), a member of the RAS superfamily, is expressed in nerve cells. Due to PINK1/PRKN and Miro1's functional relationship, an excess of mitochondrial calcium culminates in the destruction of dopaminergic neurons. An interlinked understanding of TDP-43, PINK1/PRKN, ASN, and Miro1 signalling in the communication among astrocytes, microglia, neurons, and immune cells within the brain explored the pathway of neuronal death and shed light on novel strategies for the diagnosis and treatment of parkinsonism. • "Parkinsonism" refers to neurological illnesses with movement issues, including PD and AR-JP. • Parkinopathy is characterized by pathogenic aggregation of PRKN at the OMM. • TDP-43 overexpression increases insoluble PRKN aggregation. • Miro1 localization to MERCs increases matrix calcium burden and reduces mitophagy. [ABSTRACT FROM AUTHOR]

Type 2 Diabetes (T2D) is associated with a state of low-grade inflammation that leads to insulin resistance under sustained high-fat and glucose (HFG) stress. Mitochondria from pancreatic beta cells play an essential role by metabolizing nutrients and generating signals required for both triggering and amplifying pathways of insulin secretion responding to HFG. However, the underlying pathway linking mitochondrial function to initiate and integrate inflammatory responses within the pancreatic beta cells under HFG stress remains poorly defined. Here, we demonstrated that HFG induced Ca 2+ -mediated deleterious effects on mitochondrial rho GTPase 1 (Miro1), a protein allowing mitochondria to move along microtubules to regulate mitochondria dynamics. This redistribution of Miro1 by HFG led to aggravation of proinflammatory responses in rat islets due to damaged mitochondria-producing reactive oxygen species (ROS). In addition, HFG-induced Ca 2+ -mediated increased expression of mitochondrial dynamin-like protein (DLP1) was assembled on the outer membrane of mitochondria to initiate fission events. Higher expression of DLP1 induced mitochondria fragmentation as expected but was not essential for ROS-induced proinflammatory responses, while Miro1-mediated mitochondrial dysfunction induced proinflammatory responses under HFG stress. Combined, we proposed in this study that HFG stress caused mtROS release mainly through Miro1-mediated effects on mitochondria in pancreatic beta cells triggering the NLRP3-dependent proinflammatory responses and, subsequently, damaged insulin secretion. [ABSTRACT FROM AUTHOR]