Dataset Information

Enhanced Ca2+-channeling complex formation at the ER-mitochondria interface underlies the pathogenesis of alcohol-associated liver disease

ABSTRACT: Ca2+ overload-induced mitochondrial dysfunction is considered as a major contributing factor in the pathogenesis of alcohol-associated liver disease (ALD). However, the initiating factors that drive mitochondrial Ca2+ accumulation in ALD remain elusive. Here, we demonstrate that an aberrant increase in mitochondria-associated ER membranes (MAMs) mediates Ca2+ accumulation-induced mitochondrial dysfunction in ALD via the formation of glucose-regulated protein 75 (GRP75)-mediated MAM Ca2+-channeling (MCC) complex. Unbiased transcriptomic analysis reveals pyruvate dehydrogenase kinase 4 (PDK4) as a prominently inducible MAM kinase in ALD. Additional mass spectrometry analysis unveils the critical role of PDK4 in promoting alcohol-induced MCC complex formation and mitochondrial dysfunction by phosphorylating GRP75. Non-phosphorylatable GRP75 mutation or genetic ablation of PDK4 prevents alcohol-induced mitochondrial Ca2+ accumulation and dysfunction. Conversely, ectopic induction of MAM formation in PDK4-deficient mice abrogate the protective effect in alcohol-induced liver injury. Together, our study defines the mediatory role of PDK4 in promoting mitochondrial dysfunction in ALD.

INSTRUMENT(S): Orbitrap Fusion Lumos

ORGANISM(S): Mus Musculus (mouse)

SUBMITTER: Byung-gyu kim

LAB HEAD: In-Kyu Lee

PROVIDER: PXD039478 | Pride | 2023-05-10

REPOSITORIES: Pride

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			Action	DRS
	GRP75_1.raw	Raw
	GRP75_2.raw	Raw
	Mudpit_GRP75_1__GRP75_1.mzid.gz	Mzid
	Mudpit_GRP75_1__GRP75_1.mzid_Mudpit_GRP75_1__GRP75_1.MGF	Mzid

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Enhanced Ca2+-channeling complex formation at the ER-mitochondria interface underlies the pathogenesis of alcohol-associated liver disease.

Thoudam Themis T Chanda Dipanjan D Lee Jung Yi JY Jung Min-Kyo MK Sinam Ibotombi Singh IS Kim Byung-Gyu BG Park Bo-Yoon BY Kwon Woong Hee WH Kim Hyo-Jeong HJ Kim Myeongjin M Lim Chae Won CW Lee Hoyul H Huh Yang Hoon YH Miller Caroline A CA Saxena Romil R Skill Nicholas J NJ Huda Nazmul N Kusumanchi Praveen P Ma Jing J Yang Zhihong Z Kim Min-Ji MJ Mun Ji Young JY Harris Robert A RA Jeon Jae-Han JH Liangpunsakul Suthat S Lee In-Kyu IK

Nature communications 20230327 1

Ca2+ overload-induced mitochondrial dysfunction is considered as a major contributing factor in the pathogenesis of alcohol-associated liver disease (ALD). However, the initiating factors that drive mitochondrial Ca2+ accumulation in ALD remain elusive. Here, we demonstrate that an aberrant increase in hepatic GRP75-mediated mitochondria-associated ER membrane (MAM) Ca2+-channeling (MCC) complex formation promotes mitochondrial dysfunction in vitro and in male mo ...[more]

PMID: 36973273

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Project description:Amyotrophic lateral sclerosis (ALS) is a rapidly progressive, fatal neurodegenerative disorder, characterized by selective loss of motor neurons (MNs). A number of causative genetic mutations underlie the disease, including mutations in the fused in sarcoma (FUS) gene, which can lead to both juvenile and late onset ALS. Although ALS results from MN’s death, there is evidence that dysfunctional glial cells, including oligodendroglia, contribute to neurodegeneration. Here, we used human induced pluripotent stem cells (hiPSCs) with a FUSR521H or a FUSP525L mutation and their isogenic controls to generate oligodendrocyte progenitor cells (OPCs) by inducing SOX10 expression from a TET-On SOX10 cassette as described previously in our lab. Mutant and control iPSC differentiated efficiently into OPCs. RNA sequencing identified a myelin sheath-related phenotype in mutant OPCs. Subsequent lipidomics studies demonstrated defects in myelin lipids, with a reduction of phospholipids in mutant OPCs. Among them, phosphatidylcholine (PC) and phosphatidylethanolamine (PE) are the most two abundant phospholipid in mammalian cells and regulate the mitochondria-associated ER membrane (MAM) integrity. Interestingly, FUSR521H mutant OPCs displayed a decrease in the PC/PE ratio, known to be associated with maintaining membrane (mitochondria) integrity. Proximity ligation assay further indicated that MAM was diminished in mutant OPCs. Moreover, mutant OPCs displayed stronger activation of unfolded protein response markers, a hallmark of increased susceptibility to endoplasmic reticulum (ER) stress, when exposed to thapsigargin, and exhibited impaired mitochondrial respiration and reduced Ca2+ signaling from ER Ca2+ stores. Taken together, these results demonstrate that FUS mutant OPCs display defects in lipid metabolism associated with MAM disruption manifested by impaired mitochondrial metabolism with increased susceptibility to ER stress and suppressed physiological Ca2+ signaling events.

Project description:Chronic low-grade inflammation is a hallmark of aging, but its etiology is not well understood. Mitochondrial dysfunction has been linked to both cellular senescence and age-related inflammation or inflammaging but fundamental mechanisms underlying these links are unclear. We analyzed age-related gene expression in different human tissues and discovered that in blood, the mRNA expression of Mitochondrial Calcium Uniporter (MCU) and its regulatory subunit MICU1 correlated inversely with age. MCU is the pore-forming subunit of a Ca2+-selective ion channel complex residing in the mitochondrial inner membrane and is the main conduit for Ca2+-influx into the mitochondrial matrix. Based on these findings we tested the simple hypothesis that mitochondrial Ca2+ uptake capacity of macrophages decreases with age. We found a significant reduction in the mitochondrial Ca2+-uptake capacity of macrophages derived from aged (80-90 weeks) mice. Notably, these macrophages display amplified cytosolic Ca2+ elevations and increased inflammatory output. To test the salience of mitochondrial calcium uptake in regulating macrophage inflammatory output, we deleted Mcu selectively in macrophages. The Mcu-/- macrophages of young mice (<25 weeks) express more inflammatory genes at baseline and show a hyper-inflammatory response when stimulated. We show that reduced mitochondrial Ca2+ amplifies cytosolic Ca2+ oscillations and potentiates downstream NFkB activation, which is central to inflammation. The regulation of inflammatory response by mitochondrial Ca2+ uptake is also seen readily in human macrophages. The siRNA-mediated knockdown of MCU in human blood derived macrophages recapitulates the phenomenon – the mitochondrial Ca2+-uptake is greatly reduced, cytosolic Ca2+ elevations are more pronounced, and the macrophages are hyper-inflammatory. Our findings pinpoint the MCU complex as a keystone molecular apparatus that links age-related changes in mitochondrial physiology to macrophage-mediated inflammation. Resident macrophages are intrinsic to every organ system and the steady erosion of their mitochondrial Ca2+-uptake capacity may play a germinal or exacerbating role in many age-related neurodegenerative, cardiometabolic, renal and musculoskeletal diseases that afflict us.

Project description:Background Chronic preconception paternal alcohol use modifies the sperm epigenome, inducing fetoplacental growth defects in the offspring of exposed males. A crucial outstanding question in the field of paternal epigenetic inheritance concerns the resilience of the male reproductive tract and the germline's capacity to recover and correct sperm-inherited epigenetic errors after stressor withdrawal. Objectives We set out to determine if measures of the sperm-inherited epigenetic program revert to match the control treatment one month after withdrawing daily alcohol treatments. Materials and Methods Using a voluntary access model, we exposed C57Bl6/J males to 10% alcohol for ten weeks, withdrew alcohol treatment for four weeks, and used RNA sequencing to examine gene expression patterns in the caput section of the epididymis. We then compared the abundance of sperm small RNA species between treatments. Results In the caput section of the epididymis, chronic alcohol exposures induced changes in the transcriptional control of genetic pathways related to mitochondrial function, oxidative phosphorylation, the generalized stress response (EIF2 signaling), and Sirtuin signaling. Subsequent analysis identified region-specific, alcohol-induced changes in mitochondrial DNA copy number across the epididymis, which correlated with increases in the mitochondrial DNA content of alcohol-exposed sperm. Notably, in the corpus section of the epididymis, increases in mitochondrial DNA copy number persisted one month after alcohol cessation. Analysis of sperm noncoding RNAs between Control and Alcohol-Exposed males one month after alcohol withdrawal revealed a ~100-fold increase in mir-196a, a microRNA induced as part of the Nuclear Factor Erythroid 2-Related Factor 2 (Nrf2)-driven cellular antioxidant response. Discussion and Conclusion Our data reveal that alcohol-induced epididymal mitochondrial dysfunction and differences in sperm noncoding RNA content persist after alcohol withdrawal. Further, differences in mir-196a and sperm mitochondrial DNA copy number may serve as viable biomarkers of adverse alterations in the sperm- inherited epigenetic program.

Dataset Information

Enhanced Ca2+-channeling complex formation at the ER-mitochondria interface underlies the pathogenesis of alcohol-associated liver disease

Dataset's files

Publications

Enhanced Ca<sup>2+</sup>-channeling complex formation at the ER-mitochondria interface underlies the pathogenesis of alcohol-associated liver disease.

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