bims-mecosi 2021-12-05 papers

Issue of 2021–12–05
five papers selected by
Verena Kohler, Stockholm University

Mitochondrion. 2021 Nov 29. pii: S1567-7249(21)00167-7. [Epub ahead of print]

Insight of the role of mitochondrial calcium homeostasis in hepatic insulin resistance.

Due to the rapid rise in the prevalence of chronic metabolic disease, more and more clinicians and basic medical researchers focus their eyesight on insulin resistance (IR), an early and central event of metabolic diseases. The occurrence and development of IR are primarily caused by excessive energy intake and reduced energy consumption. Liver is the central organ that controls glucose homeostasis, playing a considerable role in systemic IR. Decreased capacity of oxidative metabolism and mitochondrial dysfunction are being blamed as the direct reason for the development of IR. Mitochondrial Ca2+ plays a fundamental role in maintaining proper mitochondrial function and redox stability. The maintaining of mitochondrial Ca2+ homeostasis requires the cooperation of ion channels in the inner and outer membrane of mitochondria, such as mitochondrial calcium uniporter complex (MCUC) and voltage-dependent anion channels (VDACs). In addition, the crosstalk between the endoplasmic reticulum (ER), lysosome and plasma membrane with mitochondria is also significant for mitochondrial calcium homeostasis, which is responsible for an efficient network of cellular Ca2+ signaling. Here, we review the recent progression in the research about the regulation factors for mitochondrial Ca2+ and how the dysregulation of mitochondrial Ca2+ homeostasis is involved in the pathogenesis of hepatic IR, providing a new perspective for further exploring the role of ion in the onset and development of IR.

Keywords: Hepatic insulin resistance; Lysosomal calcium; Mitochondria-associated ER membranes; Mitochondrial calcium; Redox system

DOI: https://doi.org/10.1016/j.mito.2021.11.007

Front Cell Dev Biol. 2021 ;9 774989

Endoplasmic Reticulum-Mitochondria Contacts: A Potential Therapy Target for Cardiovascular Remodeling-Associated Diseases.

Yu Wang, Xinrong Zhang, Ya Wen, Sixuan Li, Xiaohui Lu, Ran Xu, Chao Li.

Cardiovascular remodeling occurs in cardiomyocytes, collagen meshes, and vascular beds in the progress of cardiac insufficiency caused by a variety of cardiac diseases such as chronic ischemic heart disease, chronic overload heart disease, myocarditis, and myocardial infarction. The morphological changes that occur as a result of remodeling are the critical pathological basis for the occurrence and development of serious diseases and also determine morbidity and mortality. Therefore, the inhibition of remodeling is an important approach to prevent and treat heart failure and other related diseases. The endoplasmic reticulum (ER) and mitochondria are tightly linked by ER-mitochondria contacts (ERMCs). ERMCs play a vital role in different signaling pathways and provide a satisfactory structural platform for the ER and mitochondria to interact and maintain the normal function of cells, mainly by involving various cellular life processes such as lipid metabolism, calcium homeostasis, mitochondrial function, ER stress, and autophagy. Studies have shown that abnormal ERMCs may promote the occurrence and development of remodeling and participate in the formation of a variety of cardiovascular remodeling-associated diseases. This review focuses on the structure and function of the ERMCs, and the potential mechanism of ERMCs involved in cardiovascular remodeling, indicating that ERMCs may be a potential target for new therapeutic strategies against cardiovascular remodeling-induced diseases.

Keywords: calcium transfer; cardiovascular remodeling; endoplasmic reticulum; mitochondria; therapeutic strategies

DOI: https://doi.org/10.3389/fcell.2021.774989

Diabetes Metab J. 2021 Nov;45(6): 853-865

Mitochondrial TFAM as a Signaling Regulator between Cellular Organelles: A Perspective on Metabolic Diseases.

Jin-Ho Koh, Yong-Woon Kim, Dae-Yun Seo, Tae-Seo Sohn.

Tissues actively involved in energy metabolism are more likely to face metabolic challenges from bioenergetic substrates and are susceptible to mitochondrial dysfunction, leading to metabolic diseases. The mitochondria receive signals regarding the metabolic states in cells and transmit them to the nucleus or endoplasmic reticulum (ER) using calcium (Ca2+) for appropriate responses. Overflux of Ca2+ in the mitochondria or dysregulation of the signaling to the nucleus and ER could increase the incidence of metabolic diseases including insulin resistance and type 2 diabetes mellitus. Mitochondrial transcription factor A (Tfam) may regulate Ca2+ flux via changing the mitochondrial membrane potential and signals to other organelles such as the nucleus and ER. Since Tfam is involved in metabolic function in the mitochondria, here, we discuss the contribution of Tfam in coordinating mitochondria-ER activities for Ca2+ flux and describe the mechanisms by which Tfam affects mitochondrial Ca2+ flux in response to metabolic challenges.

Keywords: Calcium; Cell nucleus; Diabetes mellitus, type 2; Endoplasmic reticulum; Mitochondria; TFAM protein

DOI: https://doi.org/10.4093/dmj.2021.0138

Commun Biol. 2021 Dec 02. 4(1): 1350

ER-misfolded proteins become sequestered with mitochondria and impair mitochondrial function.

Adrián Cortés Sanchón, Harshitha Santhosh Kumar, Matilde Mantovani, Ivan Osinnii, José María Mateos, Andres Kaech, Dimitri Shcherbakov, Rashid Akbergenov, Erik C Böttger.

Proteostasis is a challenge for cellular organisms, as all known protein synthesis machineries are error-prone. Here we show by cell fractionation and microscopy studies that misfolded proteins formed in the endoplasmic reticulum can become associated with and partly transported into mitochondria, resulting in impaired mitochondrial function. Blocking the endoplasmic reticulum-mitochondria encounter structure (ERMES), but not the mitochondrial sorting and assembly machinery (SAM) or the mitochondrial surveillance pathway components Msp1 and Vms1, abrogated mitochondrial sequestration of ER-misfolded proteins. We term this mitochondria-associated proteostatic mechanism for ER-misfolded proteins ERAMS (ER-associated mitochondrial sequestration). We testify to the relevance of this pathway by using mutant α-1-antitrypsin as an example of a human disease-related misfolded ER protein, and we hypothesize that ERAMS plays a role in pathological features such as mitochondrial dysfunction.

DOI: https://doi.org/10.1038/s42003-021-02873-w

Clin Transl Med. 2021 11;11(11): e626

New focuses on roles of communications between endoplasmic reticulum and mitochondria in identification of biomarkers and targets.

Linlin Zhang, Furong Yan, Liyang Li, Huirong Fu, Dongli Song, Duojiao Wu, Xiangdong Wang.

The communication between endoplasmic reticulum (ER) and mitochondria (Mt) plays important roles in maintenance of intra- and extra-cellular microenvironment, metabolisms, signaling activities and cell-cell communication. The present review aims to overview the advanced understanding about roles of ER-Mt structural contacts, molecular interactions and chemical exchanges, signal transmissions and inter-organelle regulations in ER-Mt communication. We address how the ER-Mt communication contributes to the regulation of lipid, amino acid and glucose metabolisms by enzymes, transporters and regulators in the process of biosynthesis. We specially emphasize the importance of deep understanding about molecular mechanisms of ER-Mt communication for identification and development of biology-specific, disease-specific and metabolism-specific biomarkers and therapeutic targets for human diseases. The inhibitors and modulators of the ER-Mt communication are categorized according to therapeutic targets. Rapid development of biotechnologies will provide new insights for spatiotemporally understanding the molecular mechanisms of ER-Mt communication.

Keywords: communications; contacts; diseases; endoplasmic reticulum; homeostasis; mitochondria

DOI: https://doi.org/10.1002/ctm2.626