bims-mionch 2024-06-16 papers

Issue of 2024–06–16
four papers selected by
Gun Kim, Seoul National University

Acta Biochim Pol. 2024 ;71 13126

Understanding mitochondrial potassium channels: 33 years after discovery.

Mitochondrial investigations have extended beyond their traditional functions, covering areas such as ATP synthesis and metabolism. Mitochondria are now implicated in new functional areas such as cytoprotection, cellular senescence, tumor function and inflammation. The basis of these new areas still relies on fundamental biochemical/biophysical mitochondrial functions such as synthesis of reactive oxygen species, mitochondrial membrane potential, and the integrity of the inner mitochondrial membrane i.e., the passage of various molecules through the mitochondrial membranes. In this view transport of potassium cations, known as the potassium cycle, plays an important role. It is believed that K+ influx is mediated by various potassium channels present in the inner mitochondrial membrane. In this article, we present an overview of the key findings and characteristics of mitochondrial potassium channels derived from research of many groups conducted over the past 33 years. We propose a list of six fundamental observations and most important ideas dealing with mitochondrial potassium channels. We also discuss the contemporary challenges and future prospects associated with research on mitochondrial potassium channels.

Keywords: cytoprotection; mitochondria; potassium channel openers; potassium channels; reactive oxygen species

DOI: https://doi.org/10.3389/abp.2024.13126

J Inherit Metab Dis. 2024 Jun 14.

Mitochondrial membrane synthesis, remodelling and cellular trafficking.

Martina Messina, Frédéric M Vaz, Shamima Rahman.

Mitochondria are dynamic cellular organelles with complex roles in metabolism and signalling. Primary mitochondrial disorders are a group of approximately 400 monogenic disorders arising from pathogenic genetic variants impacting mitochondrial structure, ultrastructure and/or function. Amongst these disorders, defects of complex lipid biosynthesis, especially of the unique mitochondrial membrane lipid cardiolipin, and membrane biology are an emerging group characterised by clinical heterogeneity, but with recurrent features including cardiomyopathy, encephalopathy, neurodegeneration, neuropathy and 3-methylglutaconic aciduria. This review discusses lipid synthesis in the mitochondrial membrane, the mitochondrial contact site and cristae organising system (MICOS), mitochondrial dynamics and trafficking, and the disorders associated with defects of each of these processes. We highlight overlapping functions of proteins involved in lipid biosynthesis and protein import into the mitochondria, pointing to an overarching coordination and synchronisation of mitochondrial functions. This review also focuses on membrane interactions between mitochondria and other organelles, namely the endoplasmic reticulum, peroxisomes, lysosomes and lipid droplets. We signpost disorders of these membrane interactions that may explain the observation of secondary mitochondrial dysfunction in heterogeneous pathological processes. Disruption of these organellar interactions ultimately impairs cellular homeostasis and organismal health, highlighting the central role of mitochondria in human health and disease.

Keywords: MAM; MERC; MICOS; cardiolipin; cell trafficking; mitochondrial lipid biosynthesis; organellar crosstalk; primary mitochondrial disease

DOI: https://doi.org/10.1002/jimd.12766

Cell Death Dis. 2024 Jun 10. 15(6): 405

Aberrant ER-mitochondria communication is a common pathomechanism in mitochondrial disease.

Patricia Morcillo, Khushbu Kabra, Kevin Velasco, Hector Cordero, Sarah Jennings, Taekyung D Yun, Delfina Larrea, H Orhan Akman, Eric A Schon.

Genetic mutations causing primary mitochondrial disease (i.e those compromising oxidative phosphorylation [OxPhos]) resulting in reduced bioenergetic output display great variability in their clinical features, but the reason for this is unknown. We hypothesized that disruption of the communication between endoplasmic reticulum (ER) and mitochondria at mitochondria-associated ER membranes (MAM) might play a role in this variability. To test this, we assayed MAM function and ER-mitochondrial communication in OxPhos-deficient cells, including cybrids from patients with selected pathogenic mtDNA mutations. Our results show that each of the various mutations studied indeed altered MAM functions, but notably, each disorder presented with a different MAM "signature". We also found that mitochondrial membrane potential is a key driver of ER-mitochondrial connectivity. Moreover, our findings demonstrate that disruption in ER-mitochondrial communication has consequences for cell survivability that go well beyond that of reduced ATP output. The findings of a "MAM-OxPhos" axis, the role of mitochondrial membrane potential in controlling this process, and the contribution of MAM dysfunction to cell death, reveal a new relationship between mitochondria and the rest of the cell, as well as providing new insights into the diagnosis and treatment of these devastating disorders.

DOI: https://doi.org/10.1038/s41419-024-06781-9

Methods Mol Biol. 2024 ;2796 185-190

Evaluation of the Role of Potassium Channels in the Proliferation, Migration, and Invasion of Blood Cells.

Valeria Y Vasileva, Vladislav I Chubinskiy-Nadezhdin.

The potassium channels are one of the key regulators of cell membrane potential and permeability properties of blood cells. The changes in functioning of potassium channels control crucial cell processes such as proliferation, viability, migration, and invasion. The correct estimation of these processes is important for the characterization of physiological and pathophysiological cell states. Here, we present the experimental protocol for evaluation of the role of potassium ion channels in the proliferation, migration, and invasion of blood cells.

Keywords: Blood cell migration; Blood cells; Invasion; Potassium channels; Proliferation

DOI: https://doi.org/10.1007/978-1-0716-3818-7_11