Mitochondrial Regulation of Diabetic Kidney Disease

The role and nature of mitochondrial dysfunction in diabetic kidney disease (DKD) has been extensively studied. Yet, the molecular drivers of mitochondrial remodeling in DKD are poorly understood. Diabetic kidney cells exhibit a cascade of mitochondrial dysfunction ranging from changes in mitochondrial morphology to significant alterations in mitochondrial biogenesis, biosynthetic, bioenergetics and production of reactive oxygen species (ROS). How these changes individually or in aggregate contribute to progression of DKD remain to be fully elucidated. Nevertheless, because of the remarkable progress in our basic understanding of the role of mitochondrial biology and its dysfunction in DKD, there is great excitement on future targeted therapies based on improving mitochondrial function in DKD. This review will highlight the latest advances in understanding the nature of mitochondria dysfunction and its role in progression of DKD, and the development of mitochondrial targets that could be potentially used to prevent its progression.

Mitochondrial Protein PGAM5 Emerges as a New Regulator in Neurological Diseases

As mitochondrial dysfunction has increasingly been implicated in neurological diseases, much of the investigation focuses on the response of the mitochondria. It appears that mitochondria can respond to external stimuli speedy fast, in seconds. Understanding how mitochondria sense the signal and communicate with cytosolic pathways are keys to understand mitochondrial regulation in diseases or in response to trauma. It was not until recently that a novel mitochondrial protein, phosphoglycerate mutase family member 5 (PGAM5) has emerged to be a new regulator of mitochondrial homeostasis. Although controversial results reveal beneficial as well as detrimental roles of PGAM5 in cancers, these findings also suggest PGAM5 may have diverse regulation on cellular physiology. Roles of PGAM5 in neuronal tissues remain to be uncovered. This review discusses current knowledge of PGAM5 in neurological diseases and provides future perspectives.

Seasonal changes of mitochondrial autophagy and oxidative response in the testis of the wild ground squirrels (Spermophilus dauricus)

Mitochondria are the main organelles for mammalian energy metabolism and have been implicated in the regulation of germ cell maintenance and spermatogenesis. However, little is known about the changes in the mitochondria of the testis of seasonal breeders. Here, we characterized the seasonal changes in the mitochondria in the testis of the wild ground squirrels. Increased testicle weight, seminiferous tubule diameter and sperm count were observed in the wild ground squirrels at the breeding season. RNA-seq analysis of the wild ground squirrel testes revealed that mitochondrial-related genes were expressed differentially between the breeding and non-breeding seasons. Immunohistochemical staining showed that key mitophagy factors including PINK1, MFN2, and PARKIN were highly expressed in various cell types of testis during the breeding season. In addition, the abundance and enzymatic activities of mitochondrial-localized antioxidative enzymes SOD2 (Superoxide dismutase 2) and Catalase were decreased in the testis during the breeding season, suggesting a tightly controlled redox balance at least partially facilitated by mitophagy during the seasonal breeding. Taken together, our study reveals that mitochondrial autophagy and oxidative stress may be implicated in the seasonal reproductive recrudescence of the wild ground squirrels, which deepens our understanding of the mitochondrial regulation of seasonal reproductivity in wildlife and provides new insights into the development of potential therapeutic interventions of male infertility.

Lipid metabolism and mitochondria: Cross talk in cancer

: Metabolic reprogramming is considered a major event in cancer initiation, progression and metastasis. The metabolic signature of cancer cells includes alterations in glycolysis, mitochondrial respiration, fatty acid/lipid and amino acid metabolism. Being at a junction of various metabolic pathways, mitochondria play a key role in fueling cancer growth through regulating bioenergetics, metabolism and cell death. Increasing evidence suggests that alteration in lipid metabolism is a common feature of metastatic progression, including fatty acid synthesis as well as fatty acid oxidation. However, the interplay between lipid metabolism and mitochondria in carcinogenesis remains obscure. The present review focuses on key lipid metabolic pathways associated with mitochondrial regulation that drive cancer phenotype and metastasis. We also review potential targets of lipid metabolism and mitochondria to improve the therapeutic regime in cancer patients. This review aims to improve our current understanding of the intricate relation of lipids with mitochondria and provides insights into new therapeutic approaches.

Mitochondrial regulation of ferroptosis

Ferroptosis is a form of iron-dependent regulated cell death driven by uncontrolled lipid peroxidation. Mitochondria are double-membrane organelles that have essential roles in energy production, cellular metabolism, and cell death regulation. However, their role in ferroptosis has been unclear and somewhat controversial. In this Perspective, I summarize the diverse metabolic processes in mitochondria that actively drive ferroptosis, discuss recently discovered mitochondria-localized defense systems that detoxify mitochondrial lipid peroxides and protect against ferroptosis, present new evidence for the roles of mitochondria in regulating ferroptosis, and outline outstanding questions on this fascinating topic for future investigations. An in-depth understanding of mitochondria functions in ferroptosis will have important implications for both fundamental cell biology and disease treatment.

The Role of Voltage-Dependent Anion Channel in Mitochondrial Dysfunction and Human Disease

The voltage-dependent anion channel (VDAC) is a β-barrel membrane protein located in the outer mitochondrial membrane (OMM). VDAC has two conductance states: an open anion selective state, and a closed and slightly cation-selective state. VDAC conductance states play major roles in regulating permeability of ATP/ADP, regulation of calcium homeostasis, calcium flux within ER-mitochondria contact sites, and apoptotic signaling events. Three reported structures of VDAC provide information on the VDAC open state via X-ray crystallography and nuclear magnetic resonance (NMR). Together, these structures provide insight on how VDAC aids metabolite transport. The interaction partners of VDAC, together with the permeability of the pore, affect the molecular pathology of diseases including Parkinson’s disease (PD), Friedreich’s ataxia (FA), lupus, and cancer. To fully address the molecular role of VDAC in disease pathology, major questions must be answered on the structural conformers of VDAC. For example, further information is needed on the structure of the closed state, how binding partners or membrane potential could lead to the open/closed states, the function and mobility of the N-terminal α-helical domain of VDAC, and the physiological role of VDAC oligomers. This review covers our current understanding of the various states of VDAC, VDAC interaction partners, and the roles they play in mitochondrial regulation pertaining to human diseases.

Nutritional Value of Moringa oleifera Lam. Leaf Powder Extracts and Their Neuroprotective Effects via Antioxidative and Mitochondrial Regulation

Age-related neurodegenerative disorders are an increasing public health problem. Oxidative stress is one of the major causes. Medicinal plant-based functional foods can be effective for these diseases. The aim of this work is to investigate the neuroprotective role of methanol extracts of Moringa oleifera leaf powder on antioxidant/oxidant imbalance and mitochondrial regulation in a H2O2-induced oxidative stress model in human neuroblastoma cells. On nutritional analysis, results showed that moringa contained 28.50% carbohydrates, 25.02% proteins, 10.42% fat, 11.83% dietary fiber, 1.108 mg β-carotene, 326.4 µg/100 g vitamin B1 and 15.2 mg/100 g vitamin C. In-vitro assays revealed that moringa methanol extracts had more phenolic content and higher antioxidant activity than acetone extracts. Moreover, pretreatments with methanol extracts showed a protective effect against H2O2-induced oxidative damage through increasing cell viability and reducing free radicals. Furthermore, the extract decreased lipid peroxidation and enhanced glutathione levels and antioxidant enzyme activity. Finally, moringa also prevented mitochondrial dysfunction by regulating calcium levels and increasing mitochondrial membrane potential. The most active concentration was 25 µg/mL. In summary, the nutritional and functional properties of Moringa oleifera as a neuroprotective agent could be beneficial to protect against oxidative stress and provide necessary nutrients for a healthy diet.

PALB2 maintains redox and mitochondrial homeostasis in the brain and cooperates with ATG7 to suppress p53 dependent neurodegeneration

The PALB2 tumor suppressor plays key roles in DNA repair and has been implicated in redox homeostasis. Autophagy maintains mitochondrial quality, mitigates oxidative stress and suppresses neurodegeneration. Here we show that Palb2 deletion in the mouse brain leads to motor deficits and that co-deletion of Palb2 with the essential autophagy gene Atg7 accelerates and exacerbates neurodegeneration induced by ATG7 loss. Palb2 deletion leads to elevated DNA damage, oxidative stress and mitochondrial markers, especially in Purkinje cells, and co-deletion of Palb2 and Atg7 results in accelerated Purkinje cell loss. Further analyses suggest that the accelerated Purkinje cell loss and severe neurodegeneration in the double deletion mice are due to oxidative stress and mitochondrial dysfunction, rather than DNA damage, and partially dependent on p53 activity. Our studies uncover a role of PALB2 in mitochondrial regulation and a cooperation between PALB2 and ATG7/autophagy in maintaining redox and mitochondrial homeostasis essential for neuronal survival.