bims-mecmid 2022-02-27 papers

bims-mecmid

Biomed News

on Membrane communication in mitochondrial dynamics

Issue of 2022–02–27
twelve papers selected by
Mauricio Cardenas Rodriguez, University of Padova

Mitochondrial Fragmentation in a High Homocysteine Environment in Diabetic Retinopathy.
Metal-Binding Propensity in the Mitochondrial Dynamin-Related Protein 1.
Inhibition of mitochondrial fission protects podocytes from albumin-induced cell damage in diabetic kidney disease.
Mitochondria Lead the Way: Mitochondrial Dynamics and Function in Cellular Movements in Development and Disease.
Increased Drp1 promotes autophagy and ESCC progression by mtDNA stress mediated cGAS-STING pathway.
SIRT3 deficiency exacerbates early-stage fibrosis after ischaemia-reperfusion-induced AKI.
Bcl-2 Family Members and the Mitochondrial Import Machineries: The Roads to Death.
Mitofusin-2 Negatively Regulates Melanogenesis by Modulating Mitochondrial ROS Generation.
PCSK9 participates in oxidized-low density lipoprotein-induced myocardial injury through mitochondrial oxidative stress and Drp1-mediated mitochondrial fission.
Nucleus Near-Infrared (nNIR) Irradiation of Single A549 Cells Induces DNA Damage and Activates EGFR Leading to Mitochondrial Fission.
Time-of-Day Circadian Modulation of Grape-Seed Procyanidin Extract (GSPE) in Hepatic Mitochondrial Dynamics in Cafeteria-Diet-Induced Obese Rats.
Broad activation of the PRKN pathway triggers synaptic failure by disrupting synaptic mitochondrial supply in early tauopathy.

Antioxidants (Basel). 2022 Feb 11. pii: 365. [Epub ahead of print]11(2):

Mitochondrial Fragmentation in a High Homocysteine Environment in Diabetic Retinopathy.

Renu A Kowluru, Ghulam Mohammad.

  Diabetic patients routinely have elevated homocysteine levels, and due to increase in oxidative stress, hyperhomocysteinemia is associated with increased mitochondrial damage. Mitochondrial homeostasis is directly related to the balance between their fission and fusion, and in diabetes this balance is disturbed. The aim of this study was to investigate the role of homocysteine in mitochondrial fission in diabetic retinopathy. Human retinal endothelial cells, either untransfected or transfected with siRNA of a fission protein (dynamin-related protein 1, Drp1) and incubated in the presence of 100 μM homocysteine, were analyzed for mitochondrial fragmentation by live-cell microscopy and GTPase activity of Drp1. Protective nucleoids and mtDNA damage were evaluated by SYBR DNA stain and by transcripts of mtDNA-encoded ND6 and cytochrome b. The role of nitrosylation of Drp1 in homocysteine-mediated exacerbation of mitochondrial fragmentation was determined by supplementing incubation medium with nitric-oxide inhibitor. Homocysteine exacerbated glucose-induced Drp1 activation and its nitrosylation, mitochondrial fragmentation and cell apoptosis, and further decreased nucleoids and mtDNA transcription. Drp1-siRNA or nitric-oxide inhibitor prevented glucose- and homocysteine-induced mitochondrial fission, damage and cell apoptosis. Thus, elevated homocysteine in a hyperglycemic environment increases Drp1 activity via increasing its nitrosylation, and this further fragments the mitochondria and increases apoptosis, ultimately leading to the development of diabetic retinopathy.

Keywords:  diabetic retinopathy; dynamin-related protein 1; homocysteine; mitochondrial dynamics; mitochondrial fission and diabetic retinopathy; nitrosylation

DOI:  https://doi.org/10.3390/antiox11020365
J Membr Biol. 2022 Feb 26.

Metal-Binding Propensity in the Mitochondrial Dynamin-Related Protein 1.

Krishnendu Roy, Thomas J Pucadyil.

  Dynamin-related protein1 (Drp1) functions to divide mitochondria and peroxisomes by binding specific adaptor proteins and lipids, both of which are integral to the limiting organellar membrane. In efforts to understand how such multivalent interactions regulate Drp1 functions, in vitro reconstitution schemes rely on recruiting soluble portions of the adaptors appended with genetically encoded polyhistidine tags onto membranes containing Ni2+-bound chelator lipids. These strategies are facile and circumvent the challenge in working with membrane proteins but assume that binding is specific to proteins carrying the polyhistidine tag. Here, we find using chelator lipids and chelator beads that both native and recombinant Drp1 directly bind Ni2+ ions. Metal binding, therefore, represents a potential strategy to deplete or purify Drp1 from native tissue lysates. Importantly, high concentrations of the metal in solution inhibit GTP hydrolysis and renders Drp1 inactive in membrane fission. Together, our results emphasize a metal-binding propensity, which could significantly impact Drp1 functions.

Keywords:  Drp1; GTPase activity; Membrane fission; Protein-lipid interactions; Transition metal binding

DOI:  https://doi.org/10.1007/s00232-022-00221-5
Biochim Biophys Acta Mol Basis Dis. 2022 Feb 21. pii: S0925-4439(22)00031-X. [Epub ahead of print]1868(5): 166368

Inhibition of mitochondrial fission protects podocytes from albumin-induced cell damage in diabetic kidney disease.

Makoto Tagaya, Shinji Kume, Mako Yasuda-Yamahara, Shogo Kuwagata, Kosuke Yamahara, Naoko Takeda, Yuki Tanaka, Masami Chin-Kanasaki, Yuki Nakae, Hideki Yokoi, Masashi Mukoyama, Naotada Ishihara, Masatoshi Nomura, Shin-Ichi Araki, Hiroshi Maegawa.

   AIMS: Identifying the mechanisms that underlie progression from endothelial damage to podocyte damage, which leads to massive proteinuria, is an urgent issue that must be clarified to improve renal outcome in diabetic kidney disease (DKD). We aimed to examine the role of dynamin-related protein 1 (Drp1)-mediated regulation of mitochondrial fission in podocytes in the pathogenesis of massive proteinuria in DKD.
METHODS: Diabetes- or albuminuria-associated changes in mitochondrial morphology in podocytes were examined by electron microscopy. The effects of albumin and other diabetes-related stimuli, including high glucose (HG), on mitochondrial morphology were examined in cultured podocytes. The role of Drp1 in podocyte damage was examined using diabetic podocyte-specific Drp1-deficient mice treated with neuraminidase, which removes endothelial glycocalyx.
RESULTS: Neuraminidase-induced removal of glomerular endothelial glycocalyx in nondiabetic mice led to microalbuminuria without podocyte damage, accompanied by reduced Drp1 expression and mitochondrial elongation in podocytes. In contrast, streptozotocin-induced diabetes significantly exacerbated neuraminidase-induced podocyte damage and albuminuria, and was accompanied by increased Drp1 expression and enhanced mitochondrial fission in podocytes. Cell culture experiments showed that albumin stimulation decreased Drp1 expression and elongated mitochondria, although HG inhibited albumin-associated changes in mitochondrial dynamics, resulting in apoptosis. Podocyte-specific Drp1-deficiency in mice prevented diabetes-related exacerbation of podocyte damage and neuraminidase-induced development of albuminuria. Endothelial dysfunction-induced albumin exposure is cytotoxic to podocytes. Inhibition of mitochondrial fission in podocytes is a cytoprotective mechanism against albumin stimulation, which is impaired under diabetic condition. Inhibition of mitochondrial fission in podocytes may represent a new therapeutic strategy for massive proteinuria in DKD.

Keywords:  Albuminuria; Diabetic kidney disease; Drp1; Mitochondrial fission; Podocyte

DOI:  https://doi.org/10.1016/j.bbadis.2022.166368
Front Cell Dev Biol. 2021 ;9 781933

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

Somya Madan, Bhavin Uttekar, Sayali Chowdhary, Richa Rikhy.

  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.

Keywords:  cell division; cell migration; embryogenesis; epithelial cell morphogenesis; epithelial to mesenchymal transition; mitochondrial fission; mitochondrial fusion; wound healing

DOI:  https://doi.org/10.3389/fcell.2021.781933
J Exp Clin Cancer Res. 2022 Feb 24. 41(1): 76

Increased Drp1 promotes autophagy and ESCC progression by mtDNA stress mediated cGAS-STING pathway.

Yujia Li, Hui Chen, Qi Yang, Lixin Wan, Jing Zhao, Yuanyuan Wu, Jiaxin Wang, Yating Yang, Menglan Niu, Hongliang Liu, Junqi Liu, Hushan Yang, Shaogui Wan, Yanming Wang, Dengke Bao.

   BACKGROUND: Mitochondrial dynamics homeostasis is important for cell metabolism, growth, proliferation, and immune responses. The critical GTPase for mitochondrial fission, Drp1 is frequently upregulated in many cancers and is closely implicated in tumorigenesis. However, the mechanism underling Drp1 to influence tumor progression is largely unknown, especially in esophageal squamous cell carcinoma (ESCC).
METHODS: Immunohistochemistry was used to examine Drp1 and LC3B expression in tissues of ESCC patients. Autophagic vesicles were investigated by transmission electron microscopy. Fluorescent LC3B puncta and mitochondrial nucleoid were observed by fluorescent and confocal microscopy. Mitochondrial function was evaluated by mitochondrial membrane potential, ROS and ATP levels. Xenograft tumor model was performed in BALB/c nude mice to analyze the role of Drp1 on ESCC progression.
RESULTS: We found that Drp1 high expression is correlated with poor overall survival of ESCC patients. Drp1 overexpression promotes cell proliferation and xenograft ESCC tumor growth by triggering autophagy. Furthermore, we demonstrated that Drp1 overexpression disturbs mitochondrial function and subsequent induces mitochondrial DNA (mtDNA) released into the cytosol thereby inducing cytosolic mtDNA stress. Mechanistically, cytosolic mtDNA activates the cGAS-STING pathway and facilitates autophagy, which promotes ESCC cancer growth. Moreover, mtDNA digestion with DNase I and autophagy inhibition with chloroquine attenuates the cGAS-STING pathway activation and ESCC cancer growth.
CONCLUSIONS: Our finding reveals that Drp1 overexpression induces mitochondrial dysfunction and cytosolic mtDNA stress, which subsequently activates the cGAS-STING pathway, triggers autophagy and promotes ESCC progression.

Keywords:  Autophagy; Drp1; Esophageal Squamous Cell Carcinoma; Mitochondrial DNA stress; cGAS-STING signaling pathway

DOI:  https://doi.org/10.1186/s13046-022-02262-z
Cell Signal. 2022 Feb 16. pii: S0898-6568(22)00044-4. [Epub ahead of print]93 110284

SIRT3 deficiency exacerbates early-stage fibrosis after ischaemia-reperfusion-induced AKI.

Lingli Cheng, Xueyan Yang, Yonghong Jian, Jie Liu, Xinyu Ke, Sha Chen, Dingwei Yang, Dingping Yang.

   BACKGROUND: Sirtuin 3 (SIRT3) is a crucial regulator of mitochondrial function and is associated with injury and repair in acute kidney injury (AKI). To investigate whether mitochondrial damage and early renal fibrosis are associated with decreased renal SIRT3 levels, we established an in vivo model.
METHODS: In vivo, we established ischaemia-reperfusion-induced AKI (IR-AKI) models in wild-type (WT) and SIRT3-knockout (SIRT3-KO) mice. Serum creatinine (Scr) and blood urea nitrogen (BUN) were measured by an automatic biochemical analyser, and renal pathological changes were examined by haematoxylin and eosin (HE) staining. Renal fibrosis in mice was assessed by Masson's trichrome staining. The expression of SIRT3, renal fibrosis-related markers (FN and α-SMA), and mitochondrial markers (DRP1, FIS1, OPA1, and MFN1) was measured by Western blotting. Morphological changes in mitochondria in renal tubular epithelial cells were analysed by transmission electron microscopy (TEM).
RESULTS: The levels of Scr and BUN were elevated with severe renal pathological damage in the IR-AKI model, especially in SIRT3-KO mice. In the IR-AKI model, the obvious increases in FN and α-SMA protein levels suggested that there was severe fibrosis in the kidney tissue, OPA1 and MFN1 protein levels were reduced while DRP1 and FIS1 protein levels were greatly increased. TEM photomicrographs showed that mitochondrial fragmentation was increased in the renal tubular epithelial cells of mice with IR injury. SIRT3-KO mice exhibited exacerbated changes.
CONCLUSION: Our findings indicate that SIRT3 plays a significant role in early-stage fibrosis after IR-AKI by regulating mitochondrial dynamics and that SIRT3 deficiency exacerbates renal dysfunction and renal fibrosis.

Keywords:  Acute kidney injury; Chronic kidney disease; Mitochondrial dynamics; Renal fibrosis; SIRT3

DOI:  https://doi.org/10.1016/j.cellsig.2022.110284
Biomolecules. 2022 Jan 19. pii: 162. [Epub ahead of print]12(2):

Bcl-2 Family Members and the Mitochondrial Import Machineries: The Roads to Death.

Lisenn Lalier, François Vallette, Stéphen Manon.

  The localization of Bcl-2 family members at the mitochondrial outer membrane (MOM) is a crucial step in the implementation of apoptosis. We review evidence showing the role of the components of the mitochondrial import machineries (translocase of the outer membrane (TOM) and the sorting and assembly machinery (SAM)) in the mitochondrial localization of Bcl-2 family members and how these machineries regulate the function of pro- and anti-apoptotic proteins in resting cells and in cells committed into apoptosis.

Keywords:  apoptosis; bcl-2 family; mitochondrial import machineries

DOI:  https://doi.org/10.3390/biom12020162
Cells. 2022 Feb 16. pii: 701. [Epub ahead of print]11(4):

Mitofusin-2 Negatively Regulates Melanogenesis by Modulating Mitochondrial ROS Generation.

Jyoti Tanwar, Suman Saurav, Reelina Basu, Jaya Bharti Singh, Anshu Priya, Maitreyee Dutta, Uma Santhanam, Manoj Joshi, Stephen Madison, Archana Singh, Nirmala Nair, Rajesh S Gokhale, Rajender K Motiani.

  Inter-organellar communication is emerging as one of the most crucial regulators of cellular physiology. One of the key regulators of inter-organellar communication is Mitofusin-2 (MFN2). MFN2 is also involved in mediating mitochondrial fusion-fission dynamics. Further, it facilitates mitochondrial crosstalk with the endoplasmic reticulum, lysosomes and melanosomes, which are lysosome-related organelles specialized in melanin synthesis within melanocytes. However, the role of MFN2 in regulating melanocyte-specific cellular function, i.e., melanogenesis, remains poorly understood. Here, using a B16 mouse melanoma cell line and primary human melanocytes, we report that MFN2 negatively regulates melanogenesis. Both the transient and stable knockdown of MFN2 leads to enhanced melanogenesis, which is associated with an increase in the number of mature (stage III and IV) melanosomes and the augmented expression of key melanogenic enzymes. Further, the ectopic expression of MFN2 in MFN2-silenced cells leads to the complete rescue of the phenotype at the cellular and molecular levels. Mechanistically, MFN2-silencing elevates mitochondrial reactive-oxygen-species (ROS) levels which in turn increases melanogenesis. ROS quenching with the antioxidant N-acetyl cysteine (NAC) reverses the MFN2-knockdown-mediated increase in melanogenesis. Moreover, MFN2 expression is significantly lower in the darkly pigmented primary human melanocytes in comparison to lightly pigmented melanocytes, highlighting a potential contribution of lower MFN2 levels to higher physiological pigmentation. Taken together, our work establishes MFN2 as a novel negative regulator of melanogenesis.

Keywords:  MFN2; melanogenesis; melanosome; mitochondria; reactive oxygen species

DOI:  https://doi.org/10.3390/cells11040701
Clin Transl Med. 2022 Feb;12(2): e729

PCSK9 participates in oxidized-low density lipoprotein-induced myocardial injury through mitochondrial oxidative stress and Drp1-mediated mitochondrial fission.

Xuan Li, Fangjie Dai, Hao Wang, Ge Wei, Qiu Jiang, Peipei Yin, Shijun Wang, Junbo Ge, Cheng Yang, Jian Wu, Yunzeng Zou.

DOI: https://doi.org/10.1002/ctm2.729
Cells. 2022 Feb 11. pii: 624. [Epub ahead of print]11(4):

Nucleus Near-Infrared (nNIR) Irradiation of Single A549 Cells Induces DNA Damage and Activates EGFR Leading to Mitochondrial Fission.

Momoh Gbetuwa, Long-Sheng Lu, Tsung-Jen Wang, Yin-Ju Chen, Jeng-Fong Chiou, Tai-Yuan Su, Tzu-Sen Yang.

  There has been great interest in identifying the biological substrate for light-cell interaction and their relations to cancer treatment. In this study, a near-infrared (NIR) laser is focused into the nucleus (nNIR) or cytoplasm (cNIR) of a single living cell by a high numerical aperture condenser to dissect the novel role of cell nucleus in mediating NIR effects on mitochondrial dynamics of A549 non-small cell lung cancer cells. Our analysis showed that nNIR, but not cNIR, triggered mitochondrial fission in 10 min. In contrast, the fission/fusion balance of mitochondria directly exposed to cNIR does not change. While the same phenomenon is also triggered by single molecular interactions between epidermal growth factor (EGF) and its receptor EGFR, pharmacological studies with cetuximab, PD153035, and caffeine suggest EGF signaling crosstalk to DNA damaging response to mediate rapid mitochondrial fission as a result of nNIR irradiation. These results suggest that nuclear DNA integrity is a novel biological target for cellular response to NIR.

Keywords:  PD153035; caffeine; cetuximab; epidermal growth factor receptor (EGFR); mitochondrial dynamic; mitochondrial fragmentation count (MFC); near infrared (NIR)

DOI:  https://doi.org/10.3390/cells11040624
Nutrients. 2022 Feb 12. pii: 774. [Epub ahead of print]14(4):

Time-of-Day Circadian Modulation of Grape-Seed Procyanidin Extract (GSPE) in Hepatic Mitochondrial Dynamics in Cafeteria-Diet-Induced Obese Rats.

Romina M Rodríguez, Antonio J Cortés-Espinar, Jorge R Soliz-Rueda, Christine Feillet-Coudray, François Casas, Marina Colom-Pellicer, Gerard Aragonès, Javier Avila-Román, Begoña Muguerza, Miquel Mulero, Maria Josepa Salvadó.

  Major susceptibility to alterations in liver function (e.g., hepatic steatosis) in a prone environment due to circadian misalignments represents a common consequence of recent sociobiological behavior (i.e., food excess and sleep deprivation). Natural compounds and, more concisely, polyphenols have been shown as an interesting tool for fighting against metabolic syndrome and related consequences. Furthermore, mitochondria have been identified as an important target for mediation of the health effects of these compounds. Additionally, mitochondrial function and dynamics are strongly regulated in a circadian way. Thus, we wondered whether some of the beneficial effects of grape-seed procyanidin extract (GSPE) on metabolic syndrome could be mediated by a circadian modulation of mitochondrial homeostasis. For this purpose, rats were subjected to "standard", "cafeteria" and "cafeteria diet + GSPE" treatments (n = 4/group) for 9 weeks (the last 4 weeks, GSPE/vehicle) of treatment, administering the extract/vehicle at diurnal or nocturnal times (ZT0 or ZT12). For circadian assessment, one hour after turning the light on (ZT1), animals were sacrificed every 6 h (ZT1, ZT7, ZT13 and ZT19). Interestingly, GSPE was able to restore the rhythm on clock hepatic genes (Bmal1, Per2, Cry1, Rorα), as this correction was more evident in nocturnal treatment. Additionally, during nocturnal treatment, an increase in hepatic fusion genes and a decrease in fission genes were observed. Regarding mitochondrial complex activity, there was a strong effect of cafeteria diet at nearly all ZTs, and GSPE was able to restore activity at discrete ZTs, mainly in the diurnal treatment (ZT0). Furthermore, a differential behavior was observed in tricarboxylic acid (TCA) metabolites between GSPE diurnal and nocturnal administration times. Therefore, GSPE may serve as a nutritional preventive strategy in the recovery of hepatic-related metabolic disease by modulating mitochondrial dynamics, which is concomitant to the restoration of the hepatic circadian machinery.

Keywords:  Zeitgebers; circadian rhythms; clock genes; grape-seed procyanidin extract; hepatic metabolism; mitochondrial dynamics; nutrition; obesity

DOI:  https://doi.org/10.3390/nu14040774
Autophagy. 2022 Feb 19. 1-3

Broad activation of the PRKN pathway triggers synaptic failure by disrupting synaptic mitochondrial supply in early tauopathy.

Yu Young Jeong, Nuo Jia, Dhasarathan Ganesan, Qian Cai.

  Mitochondrial defects are a hallmark of Alzheimer disease (AD), with pathologically phosphorylated MAPT/tau (phospho-MAPT/tau) reported to induce mitochondrial damage. Mitophagy constitutes a key pathway of mitochondrial quality control by which damaged mitochondria are sequestered within autophagosomes for lysosomal degradation. However, the mechanistic understanding of mitophagy and its association with pathologies under tauopathy conditions remains very limited. Here, we reveal that mitochondrial stress under phospho-MAPT/tau-mediated challenges broadly activates PRKN-mediated mitophagy which induces an unexpected effect - depletion of mitochondria from synaptic terminals, a characteristic feature in early tauopathy. PRKN activation accelerates RHOT1 turnover and consequently halts RHOT1-mediated mitochondrial anterograde movement, which disrupts mitochondrial supply to tauopathy synapses and thereby impairs synaptic function. Strikingly, increasing RHOT1 levels prevents synapse loss and reverses cognitive impairment in tauopathy mice by restoring synaptic mitochondrial populations. Thus, our study uncovers an important early mechanism underlying tauopathy-linked synaptic failure and opens a new avenue for specifically targeting early synaptic dysfunction in tauopathies, including AD.Abbreviations: AAV: adeno-associated virus; AD: Alzheimer disease; FTD: Frontotemporal dementia; LTP: long-term potentiation; Δψm: mitochondrial membrane potential; Phospho-MAPT/tau: hyperphosphorylated Microtubule Associated Protein Tau/tau; RHOT1: ras homolog family member T1; RNAi: RNA interference; Tg: transgenic.

Keywords:  Alzheimer; PRKN; RHOT1; mitochondrial anterograde transport; mitophagy; synaptic dysfunction; synaptic mitochondrial deficits; tauopathy

DOI:  https://doi.org/10.1080/15548627.2022.2039987