Structural and functional remodeling of mitochondria as an adaptive response to energy deprivation

MTFR1 phosphorylation-activated adaptive mitochondrial fusion is essential for colon cancer cell survival during glucose deprivation

BACKGROUND

Mitochondrial dynamics are essential for maintaining cellular function under metabolic stress. However, their role in colon cancer's response to glucose deprivation remains poorly understood.

METHODS

The role of the mitochondrial protein MTFR1 in colon cancer proliferation was evaluated using CCK-8 and colony formation assays. Mass spectrometry identified MTFR1-interacting proteins and phosphorylation sites. Mitochondrial morphology was examined with Mitotracker staining, and mitochondrial function was evaluated using MitoSOX, JC-1 staining, and the Seahorse cell mitochondrial stress test.

RESULTS

We observed that MTFR1 is highly expressed in colon cancer cells and interacts with NEK1 under glucose deprivation. This interaction induces phosphorylation of MTFR1 at serine 119, which promotes mitochondrial fusion and supports mitochondrial function. Consequently, enhanced oxidative phosphorylation improves cellular tolerance to glucose deprivation.

CONCLUSIONS

Our findings highlight the importance of MTFR1 in modulating mitochondrial dynamics and its potential impact on colon cancer cell survival under metabolic stress. These results suggest that MTFR1 serine 119 could be a key regulator of colon cancer cell metabolism and a potential therapeutic target for enhancing cancer cell response to metabolic challenges.

The role of mitochondrial biogenesis, mitochondrial dynamics and mitophagy in gastrointestinal tumors

Gastrointestinal tumors remain the leading causes of cancer-related deaths, and their morbidity and mortality remain high, which imposes a great socio-economic burden globally. Mitochondrial homeostasis depend on proper function and interaction of mitochondrial biogenesis, mitochondrial dynamics (fission and fusion) and mitophagy. Recent studies have demonstrated close implication of mitochondrial homeostasis in gastrointestinal tumorigenesis and development. In this review, we summarized the research progress on gastrointestinal tumors and mitochondrial quality control, as well as the underlying molecular mechanisms. It is anticipated that the comprehensive understanding of mitochondrial homeostasis in gastrointestinal carcinogenesis would benefit the application of mitochondria-targeted therapies for gastrointestinal tumors in future.

Coenzyme Q improves mitochondrial and muscle dysfunction caused by CUG expanded repeats in Caenorhabditis elegans

Expansion of nucleotide repeat sequences is associated with more than 40 human neuromuscular disorders. The different pathogenic mechanisms associated with the expression of nucleotide repeats are not well understood. We use a Caenorhabditis elegans model that expresses expanded CUG repeats only in cells of the body wall muscle and recapitulate muscle dysfunction and impaired organismal motility to identify the basis by which expression of RNA repeats is toxic to muscle function. Here, we performed 2 consecutive RNA interference screens and uncovered coenzyme Q metabolism and mitochondrial dysfunction as critical genetic modifiers of the motility phenotype. Furthermore, coenzyme Q supplementation reduced the toxic phenotypes, ameliorating the motility impairment and mitochondrial phenotypes. Together our data show how the expression of expanded RNA repeats can be toxic to mitochondrial homeostasis.

Sea cucumber-derived extract can protect skin cells from oxidative DNA damage and mitochondrial degradation, and promote wound healing

Our skin serves as the primary barrier against external environmental insults, the latter of which can cause oxidative stress within cells, while various bioactive peptides sourced from natural resources hold promise in protecting cells against such oxidative stress. In this study, we investigate the efficacy of a low molecular weight extract from the sea cucumber Apostichopus japonicus, denoted as Sample-P, in facilitating cell migration and wound healing under oxidative stress conditions in skin cells. The naturally derived compound is a highly complex mix of peptides exhibiting antioxidative properties, as highlighted through liquid chromatography-mass spectrometry peptide screening and an in vitro antioxidant assay. Our results demonstrate that Sample-P is capable of promoting cell migration while preventing severe stress responses such as visible through mTOR expression. To further identify the molecular pathways underpinning the overall protective mechanism of Sample-P, we have utilised a proteomics approach. Our data reveal that Sample-P regulates protein expression associated with ribosomal pathways, glycolysis/gluconeogenesis and protein processing in the endoplasmic reticulum (ER), which help in preserving DNA integrity and safeguarding cellular organelles, such as mitochondria and the ER, under oxidative stress conditions in skin cells. In summary, in the presence of H2O2, Sample-P exhibits antioxidative properties at both molecular and cellular levels, rendering it a promising candidate for topical skin treatment to wound healing and to address age-related skin conditions.

Mitochondrial fusion-fission dynamics and its involvement in colorectal cancer

The incidence and mortality rates of colorectal cancer have elevated its status as a significant public health concern. Recent research has elucidated the crucial role of mitochondrial fusion-fission dynamics in the initiation and progression of colorectal cancer. Elevated mitochondrial fission or fusion activity can contribute to the metabolic reprogramming of tumor cells, thereby activating oncogenic pathways that drive cell proliferation, invasion, migration, and drug resistance. Nevertheless, excessive mitochondrial fission can induce apoptosis, whereas moderate mitochondrial fusion can protect cells from oxidative stress. This imbalance in mitochondrial dynamics can exert dual roles as both promoters and inhibitors of colorectal cancer progression. This review provides an in-depth analysis of the fusion-fission dynamics and the underlying pathological mechanisms in colorectal cancer cells. Additionally, it offers partial insights into the mitochondrial kinetics in colorectal cancer-associated cells, such as immune and endothelial cells. This review is aimed at identifying key molecular events involved in colorectal cancer progression and highlighting the potential of mitochondrial dynamic proteins as emerging targets for pharmacological intervention.

Mitochondrial dynamics and colorectal cancer biology: mechanisms and potential targets

Colorectal cancer (CRC) is a significant public health concern, and its development is associated with mitochondrial dysfunction. Mitochondria can adapt to the high metabolic demands of cancer cells owing to their plasticity and dynamic nature. The fusion-fission dynamics of mitochondria play a crucial role in signal transduction and metabolic functions of CRC cells. Enhanced mitochondrial fission promotes the metabolic reprogramming of CRC cells, leading to cell proliferation, metastasis, and chemoresistance. Excessive fission can also trigger mitochondria-mediated apoptosis. In contrast, excessive mitochondrial fusion leads to adenosine triphosphate (ATP) overproduction and abnormal tumor proliferation, whereas moderate fusion protects intestinal epithelial cells from oxidative stress-induced mitochondrial damage, thus preventing colitis-associated cancer (CAC). Therefore, an imbalance in mitochondrial dynamics can either promote or inhibit CRC progression. This review provides an overview of the mechanism underlying mitochondrial fusion-fission dynamics and their impact on CRC biology. This revealed the dual role of mitochondrial fusion-fission dynamics in CRC development and identified potential drug targets. Additionally, this study partially explored mitochondrial dynamics in immune and vascular endothelial cells in the tumor microenvironment, suggesting promising prospects for targeting key fusion/fission effector proteins against CRC.

The Role of Swelling in the Regulation of OPA1-Mediated Mitochondrial Function in the Heart In Vitro

Optic atrophy-1 (OPA1) plays a crucial role in the regulation of mitochondria fusion and participates in maintaining the structural integrity of mitochondrial cristae. Here we elucidate the role of OPA1 cleavage induced by calcium swelling in the presence of Myls22 (an OPA1 GTPase activity inhibitor) and TPEN (an OMA1 inhibitor). The rate of ADP-stimulated respiration was found diminished by both inhibitors, and they did not prevent Ca2+-induced mitochondrial respiratory dysfunction, membrane depolarization, or swelling. L-OPA1 cleavage was stimulated at state 3 respiration; therefore, our data suggest that L-OPA1 cleavage produces S-OPA1 to maintain mitochondrial bioenergetics in response to stress.

Diet-Induced Glial Insulin Resistance Impairs The Clearance Of Neuronal Debris

Obesity significantly increases the risk of developing neurodegenerative disorders, yet the precise mechanisms underlying this connection remain unclear. Defects in glial phagocytic function are a key feature of neurodegenerative disorders, as delayed clearance of neuronal debris can result in inflammation, neuronal death, and poor nervous system recovery. Mounting evidence indicates that glial function can affect feeding behavior, weight, and systemic metabolism, suggesting that diet may play a role in regulating glial function. While it is appreciated that glial cells are insulin sensitive, whether obesogenic diets can induce glial insulin resistance and thereby impair glial phagocytic function remains unknown. Here, using a Drosophila model, we show that a chronic obesogenic diet induces glial insulin resistance and impairs the clearance of neuronal debris. Specifically, obesogenic diet exposure downregulates the basal and injury-induced expression of the glia-associated phagocytic receptor, Draper. Constitutive activation of systemic insulin release from Drosophila Insulin-producing cells (IPCs) mimics the effect of diet-induced obesity on glial draper expression. In contrast, genetically attenuating systemic insulin release from the IPCs rescues diet-induced glial insulin resistance and draper expression. Significantly, we show that genetically stimulating Phosphoinositide 3-kinase (PI3K), a downstream effector of Insulin receptor signaling, rescues HSD-induced glial defects. Hence, we establish that obesogenic diets impair glial phagocytic function and delays the clearance of neuronal debris.

Mfn2-mediated mitochondrial fusion alleviates doxorubicin-induced cardiotoxicity with enhancing its anticancer activity through metabolic switch

Imbalanced mitochondrial dynamics including inhibited mitochondrial fusion is associated with cardiac dysfunction as well as tumorigenesis. This study sought to explore the effects of promoting mitochondrial fusion on doxorubicin(Dox)-induced cardiotoxicity and its antitumor efficacy, with a focus on the underlying metabolic mechanisms. Herein, the inhibition of Mfn2-mediated mitochondrial fusion was identified as a key phenotype in Dox-induced cardiotoxicity. Restoration of Mfn2-mediated mitochondrial fusion enhanced mitochondrial oxidative metabolism, reduced cellular injury/apoptosis and inhibited mitochondria-derived oxidative stress in the Dox-treated cardiomyocytes. Application of lentivirus expressing Drp1 (mitochondrial fusion inhibitor) or Rote/Anti A (mitochondrial complex I/III inhibitors) blunted the above protective effects of Mfn2. Cardiac-specific Mfn2 transgenic mice showed preserved mitochondrial fusion and attenuated myocardial injury upon Dox exposure in vivo. The suppression of Mfn2-mediated mitochondrial fusion was induced by Dox-elicited upregulation of FoxO1, which inhibited the transcription of Mfn2 by binding to its promoter sites. In the B16 melanoma, Mfn2 upregulation not only attenuated tumor growth alone but also further delayed tumor growth in the presence of Dox. Mechanistically, Mfn2 synergized with the inhibitory action of Dox on glycolysis metabolism in the tumor cells. One common feature in both cardiomyocytes and tumor cells was that Mfn2 increased the ratio of oxygen consumption rate to extracellular acidification rate, suggesting Mfn2 triggered a shift from aerobic glycolysis to mitochondrial oxidative metabolism. In conclusion, targeting Mfn2-mediated mitochondrial fusion may provide a dual therapeutic advantage in Dox-based chemotherapy by simultaneously defending against Dox-induced cardiotoxicity and boosting its antitumor potency via metabolic shift.

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Dox exposure inhibits Mfn2-mediated mitochondrial fusion in the hearts.

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The reduction of Mfn2 is mediated by FoxO1 in a transcriptional manner.

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Mfn2 overexpression reduces Dox-induced injury and enhances its anticancer action.

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Mfn2 induces a shift from aerobic glycolysis to mitochondrial oxidative metabolism.

Mitochondrial dynamics regulators: implications for therapeutic intervention in cancer

Regardless of the recent advances in therapeutic developments, cancer is still among the primary causes of death globally, indicating the need for alternative therapeutic strategies. Mitochondria, a dynamic organelle, continuously undergo the fusion and fission processes to meet cell requirements. The balanced fission and fusion processes, referred to as mitochondrial dynamics, coordinate mitochondrial shape, size, number, energy metabolism, cell cycle, mitophagy, and apoptosis. An imbalance between these opposing events alters mitochondWangrial dynamics, affects the overall mitochondrial shape, and deregulates mitochondrial function. Emerging evidence indicates that alteration of mitochondrial dynamics contributes to various aspects of tumorigenesis and cancer progression. Therefore, targeting the mitochondrial dynamics regulator could be a potential therapeutic approach for cancer treatment. This review will address the role of imbalanced mitochondrial dynamics in mitochondrial dysfunction during cancer progression. We will outline the clinical significance of mitochondrial dynamics regulators in various cancer types with recent updates in cancer stemness and chemoresistance and its therapeutic potential and clinical utility as a predictive biomarker.