Wounding triggers MIRO-1 dependent mitochondrial fragmentation that accelerates epidermal wound closure through oxidative signaling

Death-Associated Protein 3 Triggers Intrinsic Apoptosis via Miro1 Upon Inducing Intracellular Calcium Changes

Mitochondrial homeostasis is essential for cell survival and function, necessitating quality control mechanisms to ensure a healthy mitochondrial network. Death-associated protein 3 (DAP3) serves as a subunit of the mitochondrial ribosome, playing a pivotal role in the translation of mitochondrial-encoded proteins. Apart from its involvement in protein synthesis, DAP3 has been implicated in the process of cell death and mitochondrial dynamics. In this study, we demonstrate that DAP3 mediates cell death via intrinsic apoptosis by triggering excessive mitochondrial fragmentation, loss of mitochondrial membrane potential (ΔΨm), ATP decline, and oxidative stress. Notably, DAP3 induces mitochondrial fragmentation through the Mitochondrial Rho GTPase 1 (Miro1), independently of the canonical fusion/fission machinery. Mechanistically, DAP3 promotes mitochondrial calcium accumulation through the MCU complex, leading to decreased cytosolic Ca2+ levels. This reduction in cytosolic Ca2+ is sensed by Miro1, which subsequently drives mitochondrial fragmentation. Depletion of Miro1 or MCU alleviates mitochondrial fragmentation, oxidative stress, and cell death. Collectively, our findings reveal a novel function of the mitoribosomal protein DAP3 in regulating calcium signalling and maintaining mitochondrial homeostasis.

Miro1 expression alters global gene expression, ERK1/2 phosphorylation, oxidation and cell cycle progression

Mitochondrial positioning supports localized energy and signaling requirements. Miro1 is necessary for attachment of mitochondria to microtubule motor proteins for trafficking. When Miro1 is deleted (Miro1-/-) from mouse embryonic fibroblasts (MEFs), mitochondria become sequestered to the perinuclear space, disrupting subcellular signaling gradients. Here, we show that Miro1-/- MEFs grow slower than Miro1+/+ and Miro1-/- MEFs stably re-expressing a Myc-Miro1 plasmid. Miro1-/- MEFs have a decreased percentage of cells in G1 and increased percentage of cells in S phase. We conducted the first ever RNA sequencing experiment dependent upon Miro1 expression and found differentially expressed genes related to MAPK signaling, cell proliferation and migration. ERK1 and ERK2 (ERK1/2, also known as MAPK3 and MAPK1, respectively) phosphorylation is elevated both spatially and temporally following serum stimulation in Miro1-/- MEFs, whereas the expression levels and oxidation of the dual specificity phosphatases (DUSP1-DUSP6) is unchanged. Finally, we found the oxidation status of ERK1/2 is increased in Miro1-/- MEFs compared to that seen in Miro1+/+ and Myc-Miro1 MEFs. These results highlight transcriptional control based off Miro1 expression and demonstrate the dynamic regulation of ERK1/2 upon deletion of Miro1 which might support the observed cell cycle and proliferation defects.

Restoration of Miro1's N-terminal GTPase function alleviates prenatal stress-induced mitochondrial fission via Drp1 modulation

BACKGROUND

Prenatal stress exposure irreversibly impairs mitochondrial dynamics, including mitochondrial trafficking and morphology in offspring, leading to neurodevelopmental and neuropsychiatric disorders in adulthood. Thus, understanding the molecular mechanism controlling mitochondrial dynamics in differentiating neurons is crucial to prevent the prenatal stress-induced impairments in behavior. We investigated the interplay between mitochondrial transport and fusion/fission in differentiating neurons exposed to prenatal stress, leading to ensuing behavior impairments, and then tried to identify the primary regulator that modulates both phenomena.

METHODS

We used primary hippocampal neurons of mice exposed to prenatal stress and human induced-pluripotent stem cell (hiPSC)-derived neurons, for investigating the impact of glucocorticoid on mitochondrial dynamics during differentiation. For constructing mouse models, we used AAV vectors into mouse pups exposed to prenatal stress to regulate protein expressions in hippocampal regions.

RESULTS

We first observed that prenatal exposure to glucocorticoids induced motility arrest and fragmentation of mitochondria in differentiating neurons derived from mouse fetuses (E18) and human induced pluripotent stem cells (hiPSCs). Further, glucocorticoid exposure during neurogenesis selectively downregulated Miro1 and increased Drp1 phosphorylation (Ser616). MIRO1 overexpression restored mitochondrial motility and increased intramitochondrial calcium influx through ER-mitochondria contact (ERMC) formation. Furthermore, we determined that the N-terminal GTPase domain of Miro1 plays a critical role in ERMC formation, which then decreased Drp1 phosphorylation (Ser616). Similarly, prenatal corticosterone exposure led to impaired neuropsychiatric and cognitive function in the offspring by affecting mitochondrial distribution and synaptogenesis, rescued by Miro1WT, but not N-terminal GTPase active form Miro1P26V, expression.

CONCLUSION

Prenatal glucocorticoid-mediated Miro1 downregulation contributes to dysfunction in mitochondrial dynamics through Drp1 phosphorylation (Ser616) in differentiating neurons.

Mitochondrial fission surveillance is coupled to Caenorhabditis elegans DNA and chromosome segregation integrity

Mitochondrial fission and fusion are tightly regulated to specify mitochondrial abundance, localization, and arrangement during cell division as well as in the diverse differentiated cell types and physiological states. However, the regulatory pathways for such mitochondrial dynamics are less explored than the mitochondrial fission and fusion components. Here we report a large-scale screen for genes that regulate mitochondrial fission. Mitochondrial fission defects cause a characteristic uneven fluorescent pattern in embryos carrying mitochondrial stress reporter genes. Using this uneven activation, we performed RNAi screens that identified 3 kinase genes from a ~ 500-kinase library and another 11 genes from 3,300 random genes that function in mitochondrial fission. Many of these identified genes play roles in chromosome segregation. We found that chromosome missegregation and genome instability lead to dysregulation of mitochondrial fission, possibly independent of DRP-1. ATL-1, the C. elegans ATR orthologue, plays a potentially protective role in alleviating the mitochondrial fission defect caused by chromosome missegregation. This establishes a screening paradigm for identifying mitochondrial fission regulators, which reveals the potential role of ATR in surveilling mitochondrial fission to mitigate dysregulation caused by improper chromosome segregation.

MIRO1 Is Required for Dynamic Increases in Mitochondria-ER Contact Sites and Mitochondrial ATP During the Cell Cycle

Mitochondria-ER contact sites (MERCS) are vital for mitochondrial dynamics, lipid exchange, Ca2+ homeostasis, and energy metabolism. We examined whether mitochondrial metabolism changes during the cell cycle depend on MERCS dynamics and are regulated by the outer mitochondrial protein mitochondrial rho GTPase 1 (MIRO1). Wound healing was assessed in mice with fibroblast-specific deletion of MIRO1. Wild-type and MIRO1-/- fibroblasts and vascular smooth muscle cells were evaluated for proliferation, cell cycle progression, number of MERCS, distance, and protein composition throughout the cell cycle. Restoration of MIRO1 mutants was used to test the role of MIRO1 domains; Ca2+ transients and mitochondrial metabolism were evaluated using biochemical, immunodetection, and fluorescence techniques. MERCS increased in number during G1/S compared with during G0, which was accompanied by a notable rise in protein-protein interactions involving VDAC1 and IP3R as well as GRP75 and MIRO1 by proximity-ligation assays. Split-GFP ER/mitochondrial contacts of 40 nm also increased. Mitochondrial Ca2+ concentration ([Ca2+]), membrane potential, and ATP levels correlated with the formation of MERCS during the cell cycle. MIRO1 deficiency blocked G1/S progression and the cell-cycle-dependent formation of MERCS and altered ER Ca2+ release and mitochondrial Ca2+ uptake. MIRO1 mutants lacking the Ca2+-sensitive EF hands or the transmembrane domain did not rescue cell proliferation or the formation of MERCS. MIRO1 controls an increase in the number of MERCS during cell cycle progression and increases mitochondrial [Ca2+], driving metabolic activity and proliferation through its EF hands.

A Chemotherapy Response-Related Gene Signature and DNAJC8 as Key Mediators of Hepatocellular Carcinoma Progression and Drug Resistance

Background

Chemotherapy resistance in hepatocellular carcinoma presents a significant challenge to improved patient outcomes. Identifying genes associated with chemotherapy response can enhance treatment strategies and prognostic models.

Methods

We analyzed the expression of chemotherapy response-related gene in hepatocellular carcinoma using TCGA and GSE109211 cohorts. We constructed a prognostic model using Least Absolute Shrinkage and Selection Operator (LASSO) analysis and assessed its efficacy using Kaplan-Meier survival analysis. Additionally, we evaluated the immune landscape and gene mutation profiles between different chemotherapy response-related gene (CRRG) subtypes. DNAJC8's role in hepatocellular carcinoma cell functions and chemotherapy resistance was further explored through gene knockdown experiments in vitro and in vivo.

Results

Differential expression analysis identified 220 common genes associated with chemotherapy response. The prognostic model incorporating seven key genes efficiently distinguished responders from non-responders and indicated poorer overall survival for the CRRG-high subtype. The CRRG value correlated with tumor stage and grade, and mutation profiles showed distinct patterns between CRRG subtypes. The CRRG-high subtype exhibited an immune-suppressive phenotype with higher expression of PD-L1 and CTLA-4. High DNAJC8 expression was linked to poor prognosis in multiple cohorts. Knocking down DNAJC8 significantly inhibited hepatocellular carcinoma cell proliferation, migration, invasion, and reduced sorafenib IC50.

Conclusion

The seven-gene CRRG model, particularly DNAJC8, holds potential for predicting chemotherapy response and serves as a therapeutic target in hepatocellular carcinoma.

Autonomous, Moisture-Driven Flexible Electrogenerative Dressing for Enhanced Wound Healing

Electrotherapy has shown considerable potential in treating chronic wounds, but conventional approaches relying on bulky external power supplies and mechanical force are limited in their clinical utility. This study introduces an autonomous, moisture-driven flexible electrogenerative dressing (AMFED) that overcomes these limitations. The AMFED integrates a moist-electric generator (MEG), an antibacterial hydrogel dressing, and concentric molybdenum (Mo) electrodes to provide a self-sustaining electrical supply and potent antibacterial activity against Staphylococcus aureus and Escherichia coli. The MEG harnesses chemical energy from moisture to produce a stable direct current of 0.61 V without external input, delivering this therapeutic electrical stimulation to the wound site through the Mo electrodes. The AMFED facilitates macrophage polarization toward reparative M2 phenotype and regulates inflammatory cytokines. Moreover, in vivo studies suggest that the AMFED group significantly enhances chronic wound healing, with an approximate 41% acceleration compared to the control group. Using a diabetic mouse wound model, the AMFED demonstrates its effectiveness in promoting nerve regulation, epithelial migration, and vasculogenesis. These findings present a novel and efficient platform for accelerating chronic wound healing.

Transcutaneous electrical acustimulation promotes wound healing in mice by modulating signaling molecules and mitochondria function

Previous research has identified a variety of factors that contribute to the development and maintenance of wounds. Concurrently, electroacupuncture has been demonstrated to facilitate wound healing. However, the effects of transcutaneous electrical acustimulation (TEA) on wound healing, as well as its relationship with key factors such as Wnt3a, TGF-β, Akt, c-Myc, VEGF-A, SP1, nitric oxide (NO), and mitochondrial function, remain largely unexplored. We hypothesize that TEA will activate the signaling factors and enhance mitochondrial functions to promote the repair of skin wounds in mice. An in vivo experimental study was conducted utilizing mouse models with skin wounds. The study comprised three groups: a TEA treatment with wound group, a skin wound model group, and a control group. Wound areas were measured by calculating the product of the length and width of each wound using calipers. Single-cell suspensions were prepared by excising the wound and the immediately surrounding tissue. These suspensions were stained with Trypan blue to assess cell viability, with specific probes to measure the rate of reactive oxygen species (ROS) positivity, and with reagents to quantify NO content. Western blotting (WB) was employed to evaluate protein levels associated with tissue changes, while quantitative polymerase chain reaction (qPCR) was used to assess RNA expression levels. Immunofluorescence staining was performed to visualize protein content and other relevant cellular structures within tissue sections. TEA exhibited anti-inflammatory properties and promoted wound healing in mice. Western blot analysis revealed that TEA enhanced the expression of proteins associated with Wnt3a, TGF-β, Akt, c-Myc, VEGF-A, and SP1 during the wound healing process. Immunofluorescence staining of tissue sections indicated that TEA upregulated the expression of COL1A1, MFN1, GRP75, GRP78, GRP75/ROS, GRP78/ROS, ISCU, and UCP1 while downregulating FIS1. Additionally, qPCR results demonstrated that TEA promoted the expression of IL-10 and miRNA205-5p while inhibiting MMP9 levels. TEA modulates various signaling molecules, influences chaperone proteins related to stress recovery responses, along with mitochondrial dynamics and metabolism.

Nonapoptotic role of EGL-1 in exopher production and neuronal health in Caenorhabditis elegans

While traditionally studied for their proapoptotic functions in activating the caspase, research suggests BH3-only proteins also have other roles such as mitochondrial dynamics regulation. Here, we find that EGL-1, the BH3-only protein in Caenorhabditis elegans, promotes the cell-autonomous production of exophers in adult neurons. Exophers are large, micron-scale vesicles that are ejected from the cell and contain cellular components such as mitochondria. EGL-1 facilitates exopher production potentially through regulation of mitochondrial dynamics. Moreover, an endogenous, low level of EGL-1 expression appears to benefit dendritic health. Our findings provide insights into the role of neuronal BH3-only protein in mitochondrial dynamics, downstream exopher production, and ultimately neuronal health.

Mitochondrial dynamics govern whole-body regeneration through stem cell pluripotency and mitonuclear balance

Tissue regeneration is a complex process involving large changes in cell proliferation, fate determination, and differentiation. Mitochondrial dynamics and metabolism play a crucial role in development and wound repair, but their function in large-scale regeneration remains poorly understood. Planarians offer an excellent model to investigate this process due to their remarkable regenerative abilities. In this study, we examine mitochondrial dynamics during planarian regeneration. We find that knockdown of the mitochondrial fusion gene, opa1, impairs both tissue regeneration and stem cell pluripotency. Interestingly, the regeneration defects caused by opa1 knockdown are rescued by simultaneous knockdown of the mitochondrial fission gene, drp1, which partially restores mitochondrial dynamics. Furthermore, we discover that Mitolow stem cells exhibit an enrichment of pluripotency due to their fate choices at earlier stages. Transcriptomic analysis reveals the delicate mitonuclear balance in metabolism and mitochondrial proteins in regeneration, controlled by mitochondrial dynamics. These findings highlight the importance of maintaining mitochondrial dynamics in large-scale tissue regeneration and suggest the potential for manipulating these dynamics to enhance stem cell functionality and regenerative processes.

FOXO3A Plays a Role in Wound Healing by Regulating Fibroblast Mitochondrial Dynamics

The skin plays a protective role against harmful environmental stress such as UV rays. Therefore, the skin is constantly exposed to potential injuries, and wound healing is a vital process for the survival of all higher organisms. Wound healing is dependent on aging and metabolic status at a whole-body level. Because the FOXO family plays a role in aging and metabolism, we investigated the molecular functions of FOXO3A in skin wound healing using FoxO3a-/- mice. We observed that FoxO3a-/- mice showed accelerated skin wound healing. During wound healing, more fibroblasts accumulated at the wound edges and migrated into the wound bed in FoxO3a-/- mice. Moreover, cell migration of dermal fibroblasts isolated from FoxO3a-/- mice was significantly induced. During the in vitro cell migration, we observed accelerated mitochondrial fragmentation and decreased oxygen consumption in the mitochondria of FoxO3a-/- fibroblasts. These changes were caused by the upregulation of mitochondrial Rho GTPase 1, which is an essential mediator of microtubule-based mitochondrial motility. Mitochondrial Rho GTPase 1 inhibition significantly attenuated cell migration, mitochondrial fragmentation, and mitochondrial recruitment to the leading edge of the cells. These data indicate that FOXO3A plays a crucial role in wound healing by regulating mitochondrial dynamics.

Miro1 expression alters global gene expression, ERK1/2 phosphorylation, oxidation, and cell cycle progression

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.

New insights into the role of cellular senescence and chronic wounds

Chronic or non-healing wounds, such as diabetic foot ulcers (DFUs), venous leg ulcers (VLUs), pressure ulcers (PUs) and wounds in the elderly etc., impose significant biological, social, and financial burdens on patients and their families. Despite ongoing efforts, effective treatments for these wounds remain elusive, costing the United States over US$25 billion annually. The wound healing process is notably slower in the elderly, partly due to cellular senescence, which plays a complex role in wound repair. High glucose levels, reactive oxygen species, and persistent inflammation are key factors that induce cellular senescence, contributing to chronic wound failure. This suggests that cellular senescence may not only drive age-related phenotypes and pathology but also be a key mediator of the decreased capacity for trauma repair. This review analyzes four aspects: characteristics of cellular senescence; cytotoxic stressors and related signaling pathways; the relationship between cellular senescence and typical chronic non-healing wounds; and current and future treatment strategies. In theory, anti-aging therapy may influence the process of chronic wound healing. However, the underlying molecular mechanism is not well understood. This review summarizes the relationship between cellular senescence and chronic wound healing to contribute to a better understanding of the mechanisms of chronic wound healing.

C. elegans epicuticlins define specific compartments in the apical extracellular matrix and function in wound repair

The apical extracellular matrix (aECM) of external epithelia often contains lipid-rich outer layers that contribute to permeability barrier function. The external aECM of nematodes is known as the cuticle and contains an external lipid-rich layer - the epicuticle. Epicuticlins are a family of tandem repeat cuticle proteins of unknown function. Here, we analyze the localization and function of the three C. elegans epicuticlins (EPIC proteins). EPIC-1 and EPIC-2 localize to the surface of the cuticle near the outer lipid layer, as well as to interfacial cuticles and adult-specific struts. EPIC-3 is expressed in dauer larvae and localizes to interfacial aECM in the buccal cavity. Skin wounding in the adult induces epic-3 expression, and EPIC proteins localize to wound sites. Null mutants lacking EPIC proteins are viable with reduced permeability barrier function and normal epicuticle lipid mobility. Loss of function in EPIC genes modifies the skin blistering phenotypes of Bli mutants and reduces survival after skin wounding. Our results suggest EPIC proteins define specific cortical compartments of the aECM and promote wound repair.

A wearable and stretchable dual-wavelength LED device for home care of chronic infected wounds

Phototherapy can offer a safe and non-invasive solution against infections, while promoting wound healing. Conventional phototherapeutic devices are bulky and limited to hospital use. To overcome these challenges, we developed a wearable, flexible red and blue LED (r&bLED) patch controlled by a mobile-connected system, enabling safe self-application at home. The patch exhibits excellent skin compatibility, flexibility, and comfort, with high safety under system supervision. Additionally, we synthesized a sprayable fibrin gel (F-gel) containing blue light-sensitive thymoquinone and red light-synergistic NADH. Combined with bLED, thymoquinone eradicated microbes and biofilms within minutes, regardless of antibiotic resistance. Furthermore, NADH and rLED synergistically improved macrophage and endothelial cell mitochondrial function, promoting wound healing, reducing inflammation, and enhancing angiogenesis, as validated in infected diabetic wounds in mice and minipigs. This innovative technology holds great promise for revolutionizing at-home phototherapy for chronic infected wounds.

Time-course swRNA-seq uncovers a hierarchical gene regulatory network in controlling the response-repair-remodeling after wounding

Wounding initiates intricate responses crucial for tissue repair and regeneration. Yet, the gene regulatory networks governing wound healing remain poorly understood. Here, employing single-worm RNA sequencing (swRNA-seq) across 12 time-points, we delineated a three-stage wound repair process in C. elegans: response, repair, and remodeling. Integrating diverse datasets, we constructed a dynamic regulatory network comprising 241 transcription regulators and their inferred targets. We identified potentially seven autoregulatory TFs and five cross-autoregulatory loops involving pqm-1 and jun-1. We revealed that TFs might interact with chromatin factors and form TF-TF combinatory modules via intrinsically disordered regions to enhance response robustness. We experimentally validated six regulators functioning in transcriptional and translocation-dependent manners. Notably, nhr-76, daf-16, nhr-84, and oef-1 are potentially required for efficient repair, while elt-2 may act as an inhibitor. These findings elucidate transcriptional responses and hierarchical regulatory networks during C. elegans wound repair, shedding light on mechanisms underlying tissue repair and regeneration.

Effects of mitochondrial transplantation on chronic pressure wound healing in a human patient

BACKGROUND AIMS

Wound healing is a multistage process that requires a concerted effort of various cell types. The intricate processes involved in the healing of wounds result in high energy requirements. Furthermore, mitochondria play a crucial role in the healing process because of their involvement in neo angiogenesis, growth factor synthesis, and cell differentiation. It is unclear how mitochondria transplantation, a promising new approach, influences wound healing.

METHODS

In this study, healthy autologous mitochondria obtained from skeletal muscle were injected into chronic pressure wounds as an intervention to promote wound healing.

RESULTS

Mitochondrial transplantation accelerated wound healing by reducing wound size, increasing granulation tissue, and hastening epithelialization.

CONCLUSIONS

This study is the first to demonstrate the therapeutic efficacy of mitochondrial transplantation in wound healing.

mTOR mutation disrupts larval zebrafish tail fin regeneration via regulating proliferation of blastema cells and mitochondrial functions

BACKGROUND

The larval zebrafish tail fin can completely regenerate in 3 days post amputation. mTOR, the main regulator of cell growth and metabolism, plays an essential role in regeneration. Lots of studies have documented the role of mTOR in regeneration. However, the mechanisms involved are still not fully elucidated.

MATERIALS AND RESULTS

This study aimed to explore the role and mechanism of mTOR in the regeneration of larval zebrafish tail fins. Initially, the spatial and temporal expression of mTOR signaling in the larval fin was examined, revealing its activation following tail fin amputation. Subsequently, a mTOR knockout (mTOR-KO) zebrafish line was created using CRISPR/Cas9 gene editing technology. The investigation demonstrated that mTOR depletion diminished the proliferative capacity of epithelial and mesenchymal cells during fin regeneration, with no discernible impact on cell apoptosis. Insight from SMART-seq analysis uncovered alterations in the cell cycle, mitochondrial functions and metabolic pathways when mTOR signaling was suppressed during fin regeneration. Furthermore, mTOR was confirmed to enhance mitochondrial functions and Ca2 + activation following fin amputation. These findings suggest a potential role for mTOR in promoting mitochondrial fission to facilitate tail fin regeneration.

CONCLUSION

In summary, our results demonstrated that mTOR played a key role in larval zebrafish tail fin regeneration, via promoting mitochondrial fission and proliferation of blastema cells.

Polarized localization of kinesin-1 and RIC-7 drives axonal mitochondria anterograde transport

Mitochondria transport is crucial for axonal mitochondria distribution and is mediated by kinesin-1-based anterograde and dynein-based retrograde motor complexes. While Miro and Milton/TRAK were identified as key adaptors between mitochondria and kinesin-1, recent studies suggest the presence of additional mechanisms. In C. elegans, ric-7 is the only single gene described so far, other than kinesin-1, that is absolutely required for axonal mitochondria localization. Using CRISPR engineering in C. elegans, we find that Miro is important but is not essential for anterograde traffic, whereas it is required for retrograde traffic. Both the endogenous RIC-7 and kinesin-1 act at the leading end to transport mitochondria anterogradely. RIC-7 binding to mitochondria requires its N-terminal domain and partially relies on MIRO-1, whereas RIC-7 accumulation at the leading end depends on its disordered region, kinesin-1, and metaxin2. We conclude that transport complexes containing kinesin-1 and RIC-7 polarize at the leading edge of mitochondria and are required for anterograde axonal transport in C. elegans.

Non-apoptotic role of EGL-1 in exopher production and neuronal health in Caenorhabditis elegans

While traditionally studied for their pro-apoptotic functions, recent research suggests BH3-only proteins also have non-apoptotic roles. Here, we find that EGL-1, the BH3-only protein in Caenorhabditis elegans, promotes the cell-autonomous production of exophers in adult neurons. Exophers are large, micron-scale vesicles that are ejected from the cell and contain cellular components such as mitochondria. EGL-1 facilitates exopher production potentially through regulation of mitochondrial dynamics. Moreover, an endogenous, low level of EGL-1 expression appears to benefit dendritic health. Our findings provide insights into the mechanistic role of BH3-only protein in mitochondrial dynamics, downstream exopher production, and ultimately neuronal health.

Force-induced tail-autotomy mitochondrial fission and biogenesis of matrix-excluded mitochondrial-derived vesicles for quality control

Mitochondria constantly fuse and divide for mitochondrial inheritance and functions. Here, we identified a distinct type of naturally occurring fission, tail-autotomy fission, wherein a tail-like thin tubule protrudes from the mitochondrial body and disconnects, resembling autotomy. Next, utilizing an optogenetic mitochondria-specific mechanostimulator, we revealed that mechanical tensile force drives tail-autotomy fission. This force-induced fission involves DRP1/MFF and endoplasmic reticulum tubule wrapping. It redistributes mitochondrial DNA, producing mitochondrial fragments with or without mitochondrial DNA for different fates. Moreover, tensile force can decouple outer and inner mitochondrial membranes, pulling out matrix-excluded tubule segments. Subsequent tail-autotomy fission separates the matrix-excluded tubule segments into matrix-excluded mitochondrial-derived vesicles (MDVs) which recruit Parkin and LC3B, indicating the unique role of tail-autotomy fission in segregating only outer membrane components for mitophagy. Sustained force promotes fission and MDV biogenesis more effectively than transient one. Our results uncover a mechanistically and functionally distinct type of fission and unveil the role of tensile forces in modulating fission and MDV biogenesis for quality control, underscoring the heterogeneity of fission and mechanoregulation of mitochondrial dynamics.

Plasma membrane repair empowers the necrotic survivors as innate immune modulators

The plasma membrane is crucial to the survival of animal cells, and damage to it can be lethal, often resulting in necrosis. However, cells possess multiple mechanisms for repairing the membrane, which allows them to maintain their integrity to some extent, and sometimes even survive. Interestingly, cells that survive a near-necrosis experience can recognize sub-lethal membrane damage and use it as a signal to secrete chemokines and cytokines, which activate the immune response. This review will present evidence of necrotic cell survival in both in vitro and in vivo systems, including in C. elegans, mouse models, and humans. We will also summarize the various membrane repair mechanisms cells use to maintain membrane integrity. Finally, we will propose a mathematical model to illustrate how near-death experiences can transform dying cells into innate immune modulators for their microenvironment. By utilizing their membrane repair activity, the biological effects of cell death can extend beyond the mere elimination of the cells.

Seconds Timescale Synthesis of Highly Stretchable Antibacterial Hydrogel for Skin Wound Closure and Epidermal Strain Sensor

Effective wound healing is critical for patient care, and the development of novel wound dressing materials that promote healing, prevent infection, and are user-friendly is of great importance, particularly in the context of point-of-care testing (POCT). This study reports the synthesis of a hydrogel material that can be produced in less than 10 s and possesses antibacterial activity against both gram-negative and gram-positive microorganisms, as well as the ability to inhibit the growth of eukaryotic cells, such as yeast. The hydrogel is formed wholly based on covalent-like hydrogen bonding interactions and exhibits excellent mechanical properties, with the ability to stretch up to more than 600% of its initial length. Furthermore, the hydrogel demonstrates ultra-fast self-healing properties, with fractures capable of being repaired within 10 s. This hydrogel can promote skin wound healing, with the added advantage of functioning as a strain sensor that generates an electrical signal in response to physical deformation. The strain sensor composed of a rubber shell realizes fast and responsive strain sensing. The findings suggest that this hydrogel has promising applications in the field of POCT for wound care, providing a new avenue for improved patient outcomes.

C. elegans epicuticlins define specific compartments in the apical extracellular matrix and function in wound repair

The apical extracellular matrix (aECM) of external epithelia often contains lipid-rich outer layers that contribute to permeability barrier function. The external aECM of nematode is known as the cuticle and contains an external lipid-rich layer, the epicuticle. Epicuticlins are a family of tandem repeat proteins originally identified as components of the insoluble fraction of the cuticular aECM and thought to localize in or near epicuticle. However, there has been little in vivo analysis of epicuticlins. Here, we report the localization analysis of the three C. elegans epicuticlins (EPIC proteins) using fluorescent protein knock-ins to visualize endogenously expressed proteins, and further examine their in vivo function using genetic null mutants. By TIRF microscopy, we find that EPIC-1 and EPIC-2 localize to the surface of the cuticle in larval and adult stages in close proximity to the outer lipid layer. EPIC-1 and EPIC-2 also localize to interfacial cuticles and adult-specific cuticle struts. EPIC-3 expression is restricted to the stress-induced dauer stage, where it localizes to interfacial aECM in the buccal cavity. Strikingly, skin wounding in the adult induces epic-3 expression, and EPIC-3::mNG localizes to wound scars. Null mutants lacking one, two, or all three EPIC proteins display reduced survival after skin wounding yet are viable with low penetrance defects in epidermal morphogenesis. Our results suggest EPIC proteins define specific aECM compartments and have roles in wound repair.

Mitochondrial transfer between cell crosstalk - An emerging role in mitochondrial quality control

Intercellular signaling and component conduction are essential for multicellular organisms' homeostasis, and mitochondrial transcellular transport is a key example of such cellular component exchange. In physiological situations, mitochondrial transfer is linked with biological development, energy coordination, and clearance of harmful components, remarkably playing important roles in maintaining mitochondrial quality. Mitochondria are engaged in many critical biological activities, like oxidative metabolism and biomolecular synthesis, and are exclusively prone to malfunction in pathological processes. Importantly, severe mitochondrial damage will further amplify the defects in the mitochondrial quality control system, which will mobilize more active mitochondrial transfer, replenish exogenous healthy mitochondria, and remove endogenous damaged mitochondria to facilitate disease outcomes. This review explores intercellular mitochondrial transport in cells, its role in cellular mitochondrial quality control, and the linking mechanisms in cellular crosstalk. We also describe advances in therapeutic strategies for diseases that target mitochondrial transfer.

ANT2 Accelerates Cutaneous Wound Healing in Aged Skin by Regulating Energy Homeostasis and Inflammation

An effective healing response is critical to healthy aging. In particular, energy homeostasis has become increasingly recognized as a factor in effective skin regeneration. ANT2 is a mediator of adenosine triphosphate import into mitochondria for energy homeostasis. Although energy homeostasis and mitochondrial integrity are critical for wound healing, the role played by ANT2 in the repair process had not been elucidated to date. In our study, we found that ANT2 expression decreased in aged skin and cellular senescence. Interestingly, overexpression of ANT2 in aged mouse skin accelerated the healing of full-thickness cutaneous wounds. In addition, upregulation of ANT2 in replicative senescent human diploid dermal fibroblasts induced their proliferation and migration, which are critical processes in wound healing. Regarding energy homeostasis, ANT2 overexpression increased the adenosine triphosphate production rate by activating glycolysis and induced mitophagy. Notably, ANT2-mediated upregulation of HSPA6 in aged human diploid dermal fibroblasts downregulated proinflammatory genes that mediate cellular senescence and mitochondrial damage. This study shows a previously uncharacterized physiological role of ANT2 in skin wound healing by regulating cell proliferation, energy homeostasis, and inflammation. Thus, our study links energy metabolism to skin homeostasis and reports, to the best of our knowledge, a previously unreported genetic factor that enhances wound healing in an aging model.

Multifaceted roles of mitochondria in wound healing and chronic wound pathogenesis

Mitochondria are intracellular organelles that play a critical role in numerous cellular processes including the regulation of metabolism, cellular stress response, and cell fate. Mitochondria themselves are subject to well-orchestrated regulation in order to maintain organelle and cellular homeostasis. Wound healing is a multifactorial process that involves the stringent regulation of several cell types and cellular processes. In the event of dysregulated wound healing, hard-to-heal chronic wounds form and can place a significant burden on healthcare systems. Importantly, treatment options remain limited owing to the multifactorial nature of chronic wound pathogenesis. One area that has received more attention in recent years is the role of mitochondria in wound healing. With regards to this, current literature has demonstrated an important role for mitochondria in several areas of wound healing and chronic wound pathogenesis including metabolism, apoptosis, and redox signalling. Additionally, the influence of mitochondrial dynamics and mitophagy has also been investigated. However, few studies have utilised patient tissue when studying mitochondria in wound healing, instead using various animal models. In this review we dissect the current knowledge of the role of mitochondria in wound healing and discuss how future research can potentially aid in the progression of wound healing research.

Progress in Pluronic F127 Derivatives for Application in Wound Healing and Repair

Pluronic F127 hydrogel biomaterial has garnered considerable attention in wound healing and repair due to its remarkable properties including temperature sensitivity, injectability, biodegradability, and maintain a moist wound environment. This comprehensive review provides an in-depth exploration of the recent advancements in Pluronic F127-derived hydrogels, such as F127-CHO, F127-NH2, and F127-DA, focusing on their applications in the treatment of various types of wounds, ranging from burns and acute wounds to infected wounds, diabetic wounds, cutaneous tumor wounds, and uterine scars. Furthermore, the review meticulously examines the intricate interaction mechanisms employed by these hydrogels within the wound microenvironment. By elucidating the underlying mechanisms, discussing the strengths and weaknesses of Pluronic F127, analyzing the current state of wound healing development, and expanding on the trend of targeting mitochondria and cells with F127 as a nanomaterial. The review enhances our understanding of the therapeutic effects of these hydrogels aims to foster the development of effective and safe wound-healing modalities. The valuable insights provided this review have the potential to inspire novel ideas for clinical treatment and facilitate the advancement of innovative wound management approaches.

Ribo-On and Ribo-Off tools using a self-cleaving ribozyme allow manipulation of endogenous gene expression in C. elegans

Investigating gene function relies on the efficient manipulation of endogenous gene expression. Currently, a limited number of tools are available to robustly manipulate endogenous gene expression between "on" and "off" states. In this study, we insert a 63 bp coding sequence of T3H38 ribozyme into the 3' untranslated region (UTR) of C. elegans endogenous genes using the CRISPR/Cas9 technology, which reduces the endogenous gene expression to a nearly undetectable level and generated loss-of-function phenotypes similar to that of the genetic null animals. To achieve conditional knockout, a cassette of loxP-flanked transcriptional termination signal and ribozyme is inserted into the 3' UTR of endogenous genes, which eliminates gene expression spatially or temporally via the controllable expression of the Cre recombinase. Conditional endogenous gene turn-on can be achieved by either injecting morpholino, which blocks the ribozyme self-cleavage activity or using the Cre recombinase to remove the loxP-flanked ribozyme. Together, our results demonstrate that these ribozyme-based tools can efficiently manipulate endogenous gene expression both in space and time and expand the toolkit for studying the functions of endogenous genes.

MIRO-1 interacts with VDAC-1 to regulate mitochondrial membrane potential in Caenorhabditis elegans

Precise regulation of mitochondrial fusion and fission is essential for cellular activity and animal development. Imbalances between these processes can lead to fragmentation and loss of normal membrane potential in individual mitochondria. In this study, we show that MIRO-1 is stochastically elevated in individual fragmented mitochondria and is required for maintaining mitochondrial membrane potential. We further observe a higher level of membrane potential in fragmented mitochondria in fzo-1 mutants and wounded animals. Moreover, MIRO-1 interacts with VDAC-1, a crucial mitochondrial ion channel located in the outer mitochondrial membrane, and this interaction depends on the residues E473 of MIRO-1 and K163 of VDAC-1. The E473G point mutation disrupts their interaction, resulting in a reduction of the mitochondrial membrane potential. Our findings suggest that MIRO-1 regulates membrane potential and maintains mitochondrial activity and animal health by interacting with VDAC-1. This study provides insight into the mechanisms underlying the stochastic maintenance of membrane potential in fragmented mitochondria.

Polarized localization of kinesin-1 and RIC-7 drives axonal mitochondria anterograde transport

Mitochondria transport is crucial for mitochondria distribution in axons and is mediated by kinesin-1-based anterograde and dynein-based retrograde motor complexes. While Miro and Milton/TRAK were identified as key adaptors between mitochondria and kinesin-1, recent studies suggest the presence of additional mechanisms. In C. elegans, ric-7 is the only single gene described so far, other than kinesin-1, that is absolutely required for axonal mitochondria localization. Using CRISPR engineering in C. elegans, we find that Miro is important but is not essential for anterograde traffic, whereas it is required for retrograde traffic. Both the endogenous RIC-7 and kinesin-1 act at the leading end to transport mitochondria anterogradely. RIC-7 recruitment to mitochondria requires its N-terminal domain and partially relies on MIRO-1, whereas RIC-7 accumulation at the leading end depends on its disordered region, kinesin-1 and metaxin2. We conclude that polarized transport complexes containing kinesin-1 and RIC-7 form at the leading edge of mitochondria, and that these complexes are required for anterograde axonal transport.

Emerging roles of mitochondria in animal regeneration

The regeneration capacity after an injury is critical to the survival of living organisms. In animals, regeneration ability can be classified into five primary types: cellular, tissue, organ, structure, and whole-body regeneration. Multiple organelles and signaling pathways are involved in the processes of initiation, progression, and completion of regeneration. Mitochondria, as intracellular signaling platforms of pleiotropic functions in animals, have recently gained attention in animal regeneration. However, most studies to date have focused on cellular and tissue regeneration. A mechanistic understanding of the mitochondrial role in large-scale regeneration is unclear. Here, we reviewed findings related to mitochondrial involvement in animal regeneration. We outlined the evidence of mitochondrial dynamics across different animal models. Moreover, we emphasized the impact of defects and perturbation in mitochondria resulting in regeneration failure. Ultimately, we discussed the regulation of aging by mitochondria in animal regeneration and recommended this for future study. We hope this review will serve as a means to advocate for more mechanistic studies of mitochondria related to animal regeneration on different scales.

Chemical Genetics Screen of EVP4593 Sensitivity in Budding Yeast Identifies Effects on Mitochondrial Structure and Function

Mitochondria are essential eukaryotic organelles. Mitochondrial dysfunction can lead to mitochondrial myopathies and may contribute to neurodegenerative diseases, cancer, and diabetes. EVP4593, a 6-aminoquinazoline derivative with therapeutic potential, has been shown to inhibit NADH-ubiquinone oxidoreductase (Complex I) of the mitochondrial electron transport chain, causing the release of reactive oxygen species (ROS) and a reduction in ATP synthesis. In isolated mitochondria, EVP4593 inhibits respiration in the nanomolar range (IC 50 = 14-25 nM). However, other EVP4593-specific effects on biological processes have also been described. Consistent with an effect on mitochondrial function in budding yeast, we find that EVP4593 [>25µM] induces a pronounced growth defect when wildtype cells are grown on a non-fermentable carbon source. This sensitivity to EVP4593 is exacerbated by deletion of PDR5 , an ABC transporter that confers multidrug resistance. To better understand the cellular pathways and processes affected by EVP4593, we conducted a genome-wide chemical genetics screen of the yeast knockout collection. The objective was to identify yeast gene deletion strains that exhibit growth defects when subjected to a sublethal concentration of EVP4593 [15µM]. Our screen identified 21 yeast genes that are required for resistance to 15µM EVP4593 in glycerol-containing media. The genes identified in our screen are functionally involved in several distinct categories including mitochondrial structure and function, translational regulation and nutritional sensing, cellular stress response and detoxification. Additionally, we identified cellular phenotypes associated with the exposure to EVP4593, including changes in mitochondrial structure. In conclusion, our study represents the first genome-wide screen in yeast to identify the genetic pathways and cell-protective mechanisms involved in EVP4593 resistance and reveals that this small molecule inhibitor affects both mitochondrial structure and function.

Dithianon exposure induces dopaminergic neurotoxicity in Caenorhabditis elegans

Dithianon is a conventional broad-spectrum protectant fungicide widely used in agriculture, but its potential neurotoxic risk to animals remains largely unknown. In this study, neurotoxic effects of Dithianon and its underlying cellular and molecular mechanisms were investigated using the nematode, Caenorhabditis elegans, as a model system. Upon chronic exposure of C. elegans to Dithianon, dopaminergic neurons were found to be vulnerable, with significant degeneration in terms of structure and function in a concentration-dependent manner. In examining toxicity mechanisms, we observed significant Dithianon-induced increases in oxidative stress and mitochondrial fragmentation, both of which are often associated with cellular stress. The present study suggests that Dithianon exposure causes dopaminergic neurotoxicity in C. elegans, by inducing oxidative stress and mitochondrial dysfunction. These findings contribute to a better understanding of Dithianon's neurotoxic potential.

Enhanced single RNA imaging reveals dynamic gene expression in live animals

Imaging endogenous mRNAs in live animals is technically challenging. Here, we describe an MS2-based signal amplification with the Suntag system that enables live-cell RNA imaging of high temporal resolution and with 8xMS2 stem-loops, which overcomes the obstacle of inserting a 1300 nt 24xMS2 into the genome for the imaging of endogenous mRNAs. Using this tool, we were able to image the activation of gene expression and the dynamics of endogenous mRNAs in the epidermis of live C. elegans.

A self-powered multifunctional dressing for active infection prevention and accelerated wound healing

Interruption of the wound healing process due to pathogenic infection remains a major health care challenge. The existing methods for wound management require power sources that hinder their utilization outside of clinical settings. Here, a next generation of wearable self-powered wound dressing is developed, which can be activated by diverse stimuli from the patient's body and provide on-demand treatment for both normal and infected wounds. The highly tunable dressing is composed of thermocatalytic bismuth telluride nanoplates (Bi₂Te₃ NPs) functionalized onto carbon fiber fabric electrodes and triggered by the surrounding temperature difference to controllably generate hydrogen peroxide to effectively inhibit bacterial growth at the wound site. The integrated electrodes are connected to a wearable triboelectric nanogenerator (TENG) to provide electrical stimulation for accelerated wound closure by enhancing cellular proliferation, migration, and angiogenesis. The reported self-powered dressing holds great potential in facilitating personalized and user-friendly wound care with improved healing outcomes.

[Research advances of various omics analyses in chronic refractory wounds on body surface]

The diagnosis and treatment of chronic refractory wounds on body surface has always been full of challenges, and it also poses a huge burden on medical care and society. High-throughput sequencing combined with omics analysis can reveal potential mechanisms of chronic wound formation, and identify potential biomarkers related to diagnosis, prognosis, and screening of chronic wound. Combined with multiple levels of omics analysis, the detailed molecular mechanism of chronic wound development can be further explored and understood, so as to provide clues for the formulation of personalized treatment methods and lay a solid foundation for the precision medicine of chronic wounds. Therefore, this review addresses the recent progress of various omics analyses in chronic refractory wounds on body surface.

Mitochondrial fragmentation and ROS signaling in wound response and repair

Mitochondria are organelles that serve numerous critical cellular functions, including energy production, Ca2+ homeostasis, redox signaling, and metabolism. These functions are intimately linked to mitochondrial morphology, which is highly dynamic and capable of rapid and transient changes to alter cellular functions in response to environmental cues and cellular demands. Mitochondrial morphology and activity are critical for various physiological processes, including wound healing. In mammals, wound healing is a complex process that requires coordinated function of multiple cell types and progresses in partially overlapping but distinct stages: hemostasis and inflammation, cell proliferation and migration, and tissue remodeling. The repair process at the single-cell level forms the basis for wound healing and regeneration in tissues. Recent findings reveal that mitochondria fulfill the intensive energy demand for wound repair and aid wound closure by cytoskeleton remodeling via morphological changes and mitochondrial reactive oxygen species (mtROS) signaling. In this review, we will mainly elucidate how wounding induces changes in mitochondrial morphology and activity and how these changes, in turn, contribute to cellular wound response and repair.

Computed tomography‐based radiomics prediction of CTLA4 expression and prognosis in clear cell renal cell carcinoma

OBJECTIVES

To predict CTLA4 expression levels and prognosis of clear cell renal cell carcinoma (ccRCC) by constructing a computed tomography-based radiomics model and establishing a nomogram using clinicopathologic factors.

METHODS

The clinicopathologic parameters and genomic data were extracted from 493 ccRCC cases of the Cancer Genome Atlas (TCGA)-KIRC database. Univariate and multivariate Cox regression and Kaplan-Meier analysis were performed for prognosis analysis. Cibersortx was applied to evaluate the immune cell composition. Radiomic features were extracted from the TCGA/the Cancer Imaging Archive (TCIA) (n = 102) datasets. The support vector machine (SVM) was employed to establish the radiomics signature for predicting CTLA4 expression. Receiver operating characteristic curve (ROC), decision curve analysis (DCA), and precision-recall curve were utilized to assess the predictive performance of the radiomics signature. Correlations between radiomics score (RS) and selected features were also evaluated. An RS-based nomogram was constructed to predict prognosis.

RESULTS

CTLA4 was significantly overexpressed in ccRCC tissues and was related to lower overall survival. A higher CTLA4 expression was independently linked to the poor prognosis (HR = 1.458, 95% CI 1.13-1.881, p = 0.004). The radiomics model for the prediction of CTLA4 expression levels (AUC = 0.769 in the training set, AUC = 0.724 in the validation set) was established using seven radiomic features. A significant elevation in infiltrating M2 macrophages was observed in the RS high group (p < 0.001). The predictive efficiencies of the RS-based nomogram measured by AUC were 0.826 at 12 months, 0.805 at 36 months, and 0.76 at 60 months.

CONCLUSIONS

CTLA4 mRNA expression status in ccRCC could be predicted noninvasively using a radiomics model based on nephrographic phase contrast-enhanced CT images. The nomogram established by combining RS and clinicopathologic factors could predict overall survival for ccRCC patients. Our findings may help stratify prognosis of ccRCC patients and identify those who may respond best to ICI-based treatments.

Selective disruption of Drp1-independent mitophagy and mitolysosome trafficking by an Alzheimer's disease relevant tau modification in a novel Caenorhabditis elegans model

Accumulation of inappropriately phosphorylated tau into neurofibrillary tangles is a defining feature of Alzheimer's disease, with Tau pT231 being an early harbinger of tau pathology. Previously, we demonstrated that expressing a single genomic copy of human phosphomimetic mutant tau (T231E) in Caenorhabditis elegans drove age-dependent neurodegeneration. A critical finding was that T231E, unlike wild-type tau, completely and selectively suppressed oxidative stress-induced mitophagy. Here, we used dynamic imaging approaches to analyze T231E-associated changes in mitochondria and mitolysosome morphology, abundance, trafficking, and stress-induced mitophagy as a function of mitochondrial fission mediator dynamin-related protein 1, which has been demonstrated to interact with hyper phosphorylated tau and contribute to Alzheimer's disease pathogenesis, as well as Pink1, a well-recognized mediator of mitochondrial quality control that works together with Parkin to support stress-induced mitophagy. T231E impacted both mitophagy and mitolysosome neurite trafficking with exquisite selectivity, sparing macroautophagy as well as lysosome and autolysosome trafficking. Both oxidative-stress-induced mitophagy and the ability of T231E to suppress it were independent of drp-1, but at least partially dependent on pink-1. Organelle trafficking was more complicated, with drp-1 and pink-1 mutants exerting independent effects, but generally supported the idea that the mitophagy phenotype is of greater physiologic impact in T231E. Collectively, our results refine the mechanistic pathway through which T231E causes neurodegeneration, demonstrating pathologic selectivity for mutations that mimic tauopathy-associated post-translational modifications, physiologic selectivity for organelles that contain damaged mitochondria, and molecular selectivity for dynamin-related protein 1-independent, Pink1-dependent, perhaps adaptive, and mitophagy.

Recruitment of tetraspanin TSP-15 to epidermal wounds promotes plasma membrane repair in C. elegans

Maintaining the integrity of the plasma membrane after cellular damage is essential for cell survival. However, it is unclear how cells repair large membrane injuries in vivo. Here, we report that the tetraspanin protein, TSP-15, is recruited to large membrane wounds and forms a ring-like structure in C. elegans epidermis and promotes membrane repair after an injury. TSP-15 recruits from the adjacent region underneath the plasma membrane to the wound site in a RAB-5-dependent manner upon membrane damage. Genetic and live-imaging analysis suggested that the endosomal sorting complex required for transport III (ESCRT III) is necessary for recruiting TSP-15 from the early endosome to the damaged membrane. Moreover, TSP-15 interacts with and is required for the accumulation of t-SNARE protein Syntaxin-2, which facilitates membrane repair. These findings provide valuable insights into the role of the conserved tetraspanin TSP-15 in the cellular repair of large wounds resulting from environmental insults.

Mitochondria Lead the Way: Mitochondrial Dynamics and Function in Cellular Movements in Development and Disease

The dynamics, distribution and activity of subcellular organelles are integral to regulating cell shape changes during various physiological processes such as epithelial cell formation, cell migration and morphogenesis. Mitochondria are famously known as the powerhouse of the cell and play an important role in buffering calcium, releasing reactive oxygen species and key metabolites for various activities in a eukaryotic cell. Mitochondrial dynamics and morphology changes regulate these functions and their regulation is, in turn, crucial for various morphogenetic processes. In this review, we evaluate recent literature which highlights the role of mitochondrial morphology and activity during cell shape changes in epithelial cell formation, cell division, cell migration and tissue morphogenesis during organism development and in disease. In general, we find that mitochondrial shape is regulated for their distribution or translocation to the sites of active cell shape dynamics or morphogenesis. Often, key metabolites released locally and molecules buffered by mitochondria play crucial roles in regulating signaling pathways that motivate changes in cell shape, mitochondrial shape and mitochondrial activity. We conclude that mechanistic analysis of interactions between mitochondrial morphology, activity, signaling pathways and cell shape changes across the various cell and animal-based model systems holds the key to deciphering the common principles for this interaction.

Redox-sensitive CDC-42 clustering promotes wound closure in C. elegans

Tissue damage induces immediate-early signals, activating Rho small GTPases to trigger actin polymerization essential for later wound repair. However, how tissue damage is sensed to activate Rho small GTPases locally remains elusive. Here, we found that wounding the C. elegans epidermis induces rapid relocalization of CDC-42 into plasma membrane-associated clusters, which subsequently recruits WASP/WSP-1 to trigger actin polymerization to close the wound. In addition, wounding induces a local transient increase and subsequent reduction of H₂O₂, which negatively regulates the clustering of CDC-42 and wound closure. CDC-42 CAAX motif-mediated prenylation and polybasic region-mediated cation-phospholipid interaction are both required for its clustering. Cysteine residues participate in intermolecular disulfide bonds to reduce membrane association and are required for negative regulation of CDC-42 clustering by H₂O₂. Collectively, our findings suggest that H₂O₂-regulated fine-tuning of CDC-42 localization can create a distinct biomolecular cluster that facilitates rapid epithelial wound repair after injury.

Sirt1 promotes tissue regeneration in zebrafish through regulating the mitochondrial unfolded protein response

The mitochondrial unfolded protein response (UPRmt) is an organellar stress signaling pathway that functions to detect and restore disruption of mitochondrial proteostasis. The UPRmt is involved in a wide range of physiological and disease conditions, including aging, stem cell maintenance, innate immunity, neurodegeneration, and cancer. Here we report that the UPRmt is integral to zebrafish fin regeneration. Taking advantage of a novel zebrafish UPRmt reporter, we observed that UPRmt activation occurs in regenerating fin tissue shortly after injury. Through chemical and genetic approaches, we discovered that the Sirt1-UPRmt pathway, best known for its role in promoting lifespan extension, is crucial for fin regeneration. The metabolism of NAD+ is an important contributor to Sirt1 activity in this context. We propose that Sirt1 activation induces mitochondrial biogenesis in injured fin tissue, which leads to UPRmt activation and promotes tissue regeneration.

Mitochondrial Miro GTPases coordinate mitochondrial and peroxisomal dynamics

Mitochondria and peroxisomes are highly dynamic, multifunctional organelles. Both perform key roles for cellular physiology and homoeostasis by mediating bioenergetics, biosynthesis, and/or signalling. To support cellular function, they must be properly distributed, of proper size, and be able to interact with other organelles. Accumulating evidence suggests that the small atypical GTPase Miro provides a central signalling node to coordinate mitochondrial as well as peroxisomal dynamics. In this review, I summarize our current understanding of Miro-dependent functions and molecular mechanisms underlying the proper distribution, size and function of mitochondria and peroxisomes.

de novo transcriptome profile of two earthworms Lampito mauritii and Drawida calebi during regeneration

Earthworms have remarkable ability to regenerate its tail and head region. However the list of genes expressed in this regeneration process has been less explored baring a few species. The current study involves the de novo transcriptome sequencing of intact tail and regenerating tail (15 day post amputation) of earthworms belonging to two different genera Lampito mauritii (Kinberg, 1867) and Drawida calebi (Gates, 1945). This study contains one de-novo and one reference based transcriptome analysis each from one genus of two earthworm genera. From a total of 119.92 million (150 × 2) reads, 112.95 million high quality adapter free reads were utilized in analysis. Assembly of high-quality reads was performed separately for Lampito mauritii (LM sample) and Drawida calebi (DC sample) that resulted in 66368 and 1,61,289 transcripts respectively. About 25.21% of transcripts were functionally annotated for DC sample and 38.27% for LM samples against Annelida sequences. A total of 239 genes were expressed exclusively in regenerated tissue compared to intact sample in DC whereas about 241 genes were exclusively expressed in regenerated tissue of LM compared to its intact sample. Majority of genes in Drawida and Lampito were dedicated to immune response, maintenance of cytoskeleton, resisting oxidative stress and promoting neuronal regeneration for cell-cell communication during tail regeneration.

•

Upregulation of genes such as beta catenin, Sox, notch, FGF, frizzled.

•

Similarity with annelid worm Capitella telesta.

Splitting up to heal: mitochondrial shape regulates signaling for focal membrane repair

Mitochondria are central to the health of eukaryotic cells. While commonly known for their bioenergetic role, mitochondria also function as signaling organelles that regulate cell stress responses capable of restoring homeostasis or leading the stressed cell to eventual death. Damage to the plasma membrane is a potentially fatal stressor incurred by all cells. Repairing plasma membrane damage requires cells to mount a rapid and localized response to injury. Accumulating evidence has identified a role for mitochondria as an important facilitator of this acute and localized repair response. However, as mitochondria are organized in a cell-wide, interconnected network, it is unclear how they collectively sense and respond to a focal injury. Here we will discuss how mitochondrial shape change is an integral part of this localized repair response. Mitochondrial fragmentation spatially restricts beneficial repair signaling, enabling a localized response to focal injury. Conservation of mitochondrial fragmentation in response to cell and tissue damage across species demonstrates that this is a universal pro-survival adaptation to injury and suggests that mitochondrial fragmentation may provide cells a mechanism to facilitate localized signaling in contexts beyond repairing plasma membrane injury.

Coordination of mitochondrial and cellular dynamics by the actin-based motor Myo19

Myosin XIX (Myo19) is an actin-based motor that competes with adaptors of microtubule-based motors for binding to the outer mitochondrial transmembrane proteins Miro1 and Miro2 (collectively Miro, also known as RhoT1 and RhoT2, respectively). Here, we investigate which mitochondrial and cellular processes depend on the coordination of Myo19 and microtubule-based motor activities. To this end, we created Myo19-deficient HEK293T cells. Mitochondria in these cells were not properly fragmented at mitosis and were partitioned asymmetrically to daughter cells. Respiratory functions of mitochondria were impaired and ROS generation was enhanced. On a cellular level, cell proliferation, cytokinesis and cell-matrix adhesion were negatively affected. On a molecular level, Myo19 regulates focal adhesions in interphase, and mitochondrial fusion and mitochondrially associated levels of fission protein Drp1 and adaptor proteins dynactin and TRAK1 at prometaphase. These alterations were due to a disturbed coordination of Myo19 and microtubule-based motor activities by Miro.

Plasma membrane integrity: implications for health and disease

Plasma membrane integrity is essential for cellular homeostasis. In vivo, cells experience plasma membrane damage from a multitude of stressors in the extra- and intra-cellular environment. To avoid lethal consequences, cells are equipped with repair pathways to restore membrane integrity. Here, we assess plasma membrane damage and repair from a whole-body perspective. We highlight the role of tissue-specific stressors in health and disease and examine membrane repair pathways across diverse cell types. Furthermore, we outline the impact of genetic and environmental factors on plasma membrane integrity and how these contribute to disease pathogenesis in different tissues.

The engine initiating tissue regeneration: does a common mechanism exist during evolution?

A successful tissue regeneration is a very complex process that requires a precise coordination of many molecular, cellular and physiological events. One of the critical steps is to convert the injury signals into regeneration signals to initiate tissue regeneration. Although many efforts have been made to investigate the mechanisms triggering tissue regeneration, the fundamental questions remain unresolved. One of the major obstacles is that the injury and the initiation of regeneration are two highly coupled processes and hard to separate from one another. In this article, we review the major events occurring at the early injury/regeneration stage in a range of species, and discuss the possible common mechanisms during initiation of tissue regeneration.