• 대한의생명과학회지
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• 제22권3호
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• pp.107-114
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• 2016

Maintenance of fasting blood glucose levels is important for glucose homeostasis. Disruption of feedback mechanisms are a major reason for elevations of glucose level in blood, which is a risk factor for type 2 diabetes mellitus that is mainly caused by malfunction of pancreatic beta-cell and insulin. The fasting blood glucose level has been known to be influenced by genetic and environmental factors. Mitochondria have many functions for cell survival and death: glucose metabolism, fatty acid oxidation, ATP generation, reactive oxygen species (ROS) metabolism, calcium handling, and apoptosis regulation. In addition to these functions, mitochondria change their morphology dynamically in response to multiple signals resulting in fusion and fission. In this study, we aimed to examine association between fasting blood glucose levels and variants of the genes that are reported to have functions in mitochondrial dynamics, fusion and fission, using a cohort study. A total 416 SNPs from 36 mitochondrial dynamics genes were selected to analyze the quantitative association with fasting glucose level. Among the 416 SNPs, 4 SNPs of PRKACB, 13 SNPs of PPP3CA, 6 SNPs of PARK2, and 3 SNPs of GDAP1 were significantly associated. In this study, we were able to confirm an association of mitochondrial dynamics genes with glucose levels. To our knowledge our study is the first to identify specific SNPs related to fasting blood glucose level.

• Mycobiology
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• 제39권4호
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• pp.235-242
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• 2011

In contrast to the nuclear genome, the mitochondrial genome does not follow Mendelian laws of inheritance. The nuclear genome of meiotic progeny comes from the recombination of both parental genomes, whereas the meiotic progeny could inherit mitochondria from one, the other, or both parents. In fact, one fascinating phenomenon is that mitochondrial DNA in the majority of eukaryotes is inherited from only one particular parent. Typically, such unidirectional and uniparental inheritance of mitochondrial DNA can be explained by the size of the gametes involved in mating, with the larger gamete contributing towards mitochondrial DNA inheritance. However, in the human fungal pathogen Cryptococcus neoformans, bisexual mating involves the fusion of two isogamous cells of mating type (MAT) a and MAT${\alpha}$, yet the mitochondrial DNA is inherited predominantly from the MATa parent. Although the exact mechanism underlying such uniparental mitochondrial inheritance in this fungus is still unclear, various hypotheses have been proposed. Elucidating the mechanism of mitochondrial inheritance in this clinically important and genetically amenable eukaryotic microbe will yield insights into general mechanisms that are likely conserved in higher eukaryotes. In this review, we highlight studies on Cryptococcus mitochondrial inheritance and point out some important questions that need to be addressed in the future.

• Archives of Pharmacal Research
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• 제17권6호
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• pp.492-496
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• 1994

• Journal of Microbiology and Biotechnology
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• 제30권8호
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• pp.1142-1148
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• 2020

Mitochondria play a vital role in iron uptake and metabolism in pathogenic fungi, and also influence virulence and drug tolerance. However, the regulation of iron transport within the mitochondria of Cryptococcus neoformans, a causative agent of fungal meningoencephalitis in immunocompromised individuals, remains largely uncharacterized. In this study, we identified and functionally characterized Mrs3/4, a homolog of the Saccharomyces cerevisiae mitochondrial iron transporter, in C. neoformans var. grubii. A strain expressing an Mrs3/4-GFP fusion protein was generated, and the mitochondrial localization of the fusion protein was confirmed. Moreover, a mutant lacking the MRS3/4 gene was constructed; this mutant displayed significantly reduced mitochondrial iron and cellular heme accumulation. In addition, impaired mitochondrial iron-sulfur cluster metabolism and altered expression of genes required for iron uptake at the plasma membrane were observed in the mrs3/4 mutant, suggesting that Mrs3/4 is involved in iron import and metabolism in the mitochondria of C. neoformans. Using a murine model of cryptococcosis, we demonstrated that an mrs3/4 mutant is defective in survival and virulence. Taken together, our study suggests that Mrs3/4 is responsible for iron import in mitochondria and reveals a link between mitochondrial iron metabolism and the virulence of C. neoformans.

• BMB Reports
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• 제50권12호
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• pp.597-598
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• 2017

Mitochondria have evolutionarily, functionally and structurally distinct outer- (OMM) and inner-membranes (IMM). Thus, mitochondrial morphology is controlled by independent but coordinated activity of fission and fusion of the OMM and IMM. Constriction and division of the OMM are mediated by endocytosis-like machineries, which include dynamin-related protein 1 with additional cytosolic vesicle scissoring machineries such as actin filament and Dynamin 2. However, structural alteration of the IMM during mitochondrial division has been poorly understood. Recently, we found that the IMM and the inner compartments undergo transient and reversible constriction prior to the OMM division, which we termed CoMIC, ${\underline{C}}onstriction$ ${\underline{o}}f$ ${\underline{M}}itochondrial$ ${\underline{I}}nner$ ${\underline{C}}ompartment$. In this short review, we further discuss the evolutionary perspective and the regulatory mechanism of CoMIC during mitochondrial division.

• BMB Reports
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• 제45권1호
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• pp.7-13
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• 2012

Phospholipase D (PLD), a superfamily of signaling enzymes that most commonly generate the lipid second messenger Phosphatidic Acid (PA), is found in diverse organisms from bacteria to man and functions in multiple cellular pathways. A fascinating member of the family, MitoPLD, is anchored to the mitochondrial surface and has two reported roles. In the first role, MitoPLD-generated PA regulates mitochondrial shape through facilitating mitochondrial fusion. In the second role, MitoPLD performs a critical function in a pathway that creates a specialized form of RNAi required by developing spermatocytes to suppress transposon mobilization during meiosis. This spermatocyte-specific RNAi, known as piRNA, is generated in the nuage, an electron-dense accumulation of RNA templates and processing proteins that localize adjacent to mitochondria in a structure also called intermitochondrial cement. In this review, we summarize recent findings on these roles for MitoPLD functions, highlighting directions that need to be pursued to define the underlying mechanisms.

• The Korean Journal of Physiology and Pharmacology
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• 제22권6호
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• pp.697-703
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• 2018

Myoblast fusion depends on mitochondrial integrity and intracellular $Ca^{2+}$ signaling regulated by various ion channels. In this study, we investigated the ionic currents associated with $[Ca^{2+}]_i$ regulation in normal and mitochondrial DNA-depleted(${\rho}0$) L6 myoblasts. The ${\rho}0$ myoblasts showed impaired myotube formation. The inwardly rectifying $K^+$ current ($I_{Kir}$) was largely decreased with reduced expression of KIR2.1, whereas the voltage-operated $Ca^{2+}$ channel and $Ca^{2+}$-activated $K^+$ channel currents were intact. Sustained inhibition of mitochondrial electron transport by antimycin A treatment (24 h) also decreased the $I_{Kir}$. The ${\rho}0$ myoblasts showed depolarized resting membrane potential and higher basal $[Ca^{2+}]_i$. Our results demonstrated the specific downregulation of $I_{Kir}$ by dysfunctional mitochondria. The resultant depolarization and altered $Ca^{2+}$ signaling might be associated with impaired myoblast fusion in ${\rho}0$ myoblasts.

• 운동영양학회지
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• 제23권1호
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• pp.28-35
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• 2019

[Purpose] The purpose of this study was to investigate the effects of treadmill exercise on oxidative stress in the hippocampal tissue and mitochondrial dynamic-related proteins in rats fed a long-term high-fat diet (HFD). [Methods] Obesity was induced in experimental animals using high fat feed, and the experimental groups were divided into a normal diet-control (ND-CON; n=12), a high fat diet-control (HFD-CON; n=12) and a high fat diet-treadmill exercise (HFD-TE; n=12) group. The rats were subsequently subjected to treadmill exercise (progressively increasing load intensity) for 8 weeks (5 min at 8 m/min, then 5 min at 11 m/min, and finally 20 min at 14 m/min). We assessed weight, triglyceride (TG) concentration, total cholesterol (TC), area under the curve, homeostatic model assessment of insulin resistance, and AVF/body weight. Western blotting was used to examine expression of proteins related to oxidative stress and mitochondrial dynamics, and immunohistochemistry was performed to examine the immunoreactivity of gp91phox. [Results] Treadmill exercise effectively improved the oxidative stress in the hippocampal tissue, expression of mitochondrial dynamic-related proteins, and activation of NADPH oxidase (gp91phox) and induced weight, blood profile, and abdominal fat loss. [Conclusion] Twenty weeks of high fat diet induced obesity, which was shown to inhibit normal mitochondria fusion and fission functions in hippocampal tissues. However, treadmill exercise was shown to have positive effects on these pathophysiological phenomena. Therefore, treadmill exercise should be considered during prevention and treatment of obesity-induced metabolic diseases.

• Nutrition Research and Practice
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• 제16권2호
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• pp.147-160
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• 2022

BACKGROUND/OBJECTIVES: Patients with chronic kidney disease (CKD) have a high concentration of uremic toxins in their blood and often experience muscle atrophy. Indoxyl sulfate (IS) is a uremic toxin produced by tryptophan metabolism. Although an elevated IS level may induce muscle dysfunction, the effect of IS on physiological concentration has not been elucidated. Additionally, the effects of ursolic acid (UA) on muscle hypertrophy have been reported in healthy models; however, it is unclear whether UA ameliorates muscle dysfunction associated with chronic diseases, such as CKD. Thus, this study aimed to investigate whether UA can improve the IS-induced impairment of mitochondrial biogenesis. MATERIALS/METHODS: C2C12 cells were incubated with or without IS (0.1 mM) and UA (1 or 2 μM) to elucidate the physiological effect of UA on CKD-related mitochondrial dysfunction and its related mechanisms using real-time reverse transcription-polymerase chain reaction, western blotting and enzyme-linked immunosorbent assay. RESULTS: IS suppressed the expression of differentiation marker genes without decreasing cell viability. IS decreased the mitochondrial DNA copy number and ATP levels by downregulating the genes pertaining to mitochondrial biogenesis (Ppargc1a, Nrf1, Tfam, Sirt1, and Mef2c), fusion (Mfn1 and Mfn2), oxidative phosphorylation (Cycs and Atp5b), and fatty acid oxidation (Pdk4, Acadm, Cpt1b, and Cd36). Furthermore, IS increased the intracellular mRNA and secretory protein levels of interleukin (IL)-6. Finally, UA ameliorated the IS-induced impairment in C2C12 cells. CONCLUSIONS: Our results indicated that UA improves the IS-induced impairment of mitochondrial biogenesis by affecting differentiation, ATP levels, and IL-6 secretion in C2C12 cells. Therefore, UA could be a novel therapeutic agent for CKD-induced muscle dysfunction.

• 생명과학회지
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• 제27권3호
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• pp.361-369
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• 2017

미토콘드리아의 항상성은 미토콘드리아 생합성과 마이토파지(자가포식에 의한 미토콘드리아 분해)로 불리는 2가지 주요 과정들에 의해 정교하게 조절되고 있다. 지구성 운동 훈련에 반응하여 골격근에서 미토콘드리아 생합성에 관한 기전들은 잘 정립되어 있는 반면 지구성 운동 훈련 후 골격근의 마이토파지 조절 기전과 마이토파지와 미토콘드리아 생합성의 협응을 조절하는 기전은 아직 명확히 밝혀져 있지 않다. 최근 연구들에 의하면 지구성 운동 훈련은 골격근에서 미토콘드리아 생합성, 미토콘드리아 역동성, 미토콘드리아 분해와 관련된 유전인자들의 발현을 증가시킨다고 하였다. 하지만 골격근에서 자가포식이 억제되었을 경우, 지구성 운동 훈련에 의한 미토콘드리아 생합성과 관련된 지표들인 Cox IV와 citrate synthase의 증가는 상쇄되었다. 따라서 자가포식과 마이토파지는 골격근의 미토콘드리아 생합성에 중요한 역할을 하며 정반대되는 이 두 과정(이화 또는 동화작용)의 협응 과정이 지구성 운동 훈련에 반응하여 대사적 기능과 지구력 운동 수행능력을 향상시키는 것과 같은 골격근의 적응에 중요한 듯하다. 지구성 운동은 미토콘드리아의 일정한 숫자를 유지시키기 위해 미토콘드리아 생합성, 미토콘드리아의 융합과 분열, 자가포식/마이토 파지들의 각각의 과정들을 조절하는 것으로 여겨진다. 지구성 운동 훈련은 골격근에서 마이토파지를 활성화시켜 미토콘드리아 양과 질을 조절하여 늙고 건강하지 않은 미토콘드리아를 젊고 건강한 미토콘드리아로 교체시킬 수 있다. 이 총론에서 미토콘드리아 생합성과 마이토파지의 분자학적 기전과 서로 상반되는 이 두 과정간의 협응이 골격근의 지구성 훈련에 대한 세포적 적응에 관련한다는 내용이 논의될 것이다.