While conventional wisdom initially postulated that PD-L1 serves as the inert ligand for PD-1, an emerging body of literature suggests that PD-L1 has cell-intrinsic functions in immune and cancer cells. In line with these studies, here we show that engagement of PD-L1 via cellular ligands or agonistic antibodies, including those used in the clinic, potently inhibits the type I interferon pathway in cancer cells. Hampered type I interferon responses in PD-L1-expressing cancer cells resulted in enhanced efficacy of oncolytic viruses in vitro and in vivo.
View Article and Find Full Text PDFCysteine, the rate-controlling amino acid in cellular glutathione synthesis is imported as cystine, by the cystine/glutamate antiporter, xCT, and subsequently reduced to cysteine. As glutathione redox is important in muscle regeneration in aging, we hypothesized that xCT exerts upstream control over skeletal muscle glutathione redox, metabolism and regeneration. Bioinformatic analyses of publicly available datasets revealed that expression levels of xCT and GSH-related genes are inversely correlated with myogenic differentiation genes.
View Article and Find Full Text PDFImpaired mitochondrial function is a hallmark of aging and a major contributor to neurodegenerative diseases. We have shown that disrupted mitochondrial dynamics typically found in aging alters the fate of neural stem cells (NSCs) leading to impairments in learning and memory. At present, little is known regarding the mechanisms by which neural stem and progenitor cells survive and adapt to mitochondrial dysfunction.
View Article and Find Full Text PDFMitochondrial electron transport chain complexes organize into supramolecular structures called respiratory supercomplexes (SCs). The role of respiratory SCs remains largely unconfirmed despite evidence supporting their necessity for mitochondrial respiratory function. The mechanisms underlying the formation of the IIIIIV "respirasome" SC are also not fully understood, further limiting insights into these processes in physiology and diseases, including neurodegeneration and metabolic syndromes.
View Article and Find Full Text PDFSARS-CoV-2 infection is associated with both acute and post-acute neurological symptoms. Emerging evidence suggests that SARS-CoV-2 can alter mitochondrial metabolism, suggesting that changes in brain metabolism may contribute to the development of acute and post-acute neurological complications. Monoamine oxidase B (MAO-B) is a flavoenzyme located on the outer mitochondrial membrane that catalyzes the oxidative deamination of monoamine neurotransmitters.
View Article and Find Full Text PDFInsulin resistance and blunted mitochondrial capacity in skeletal muscle are often synonymous, however, this association remains controversial. The aim of this study was to perform an in-depth multifactorial comparison of skeletal muscle mitochondrial capacity between individuals who were lean and active (Active, = 9), individuals with obesity (Obese, = 9), and individuals with obesity, insulin resistance, and type 2 diabetes (T2D, = 22). Mitochondrial capacity was assessed by ex vivo mitochondrial respiration with fatty-acid and glycolytic-supported protocols adjusted for mitochondrial content (mtDNA and citrate synthase activity).
View Article and Find Full Text PDFNatural killer (NK) cells are predominant innate lymphocytes that initiate the early immune response during infection. NK cells undergo a metabolic switch to fuel augmented proliferation and activation following infection. Tumor necrosis factor-alpha (TNFα) is a well-known inflammatory cytokine that enhances NK cell function; however, the mechanism underlying NK cell proliferation in response to TNFα is not well established.
View Article and Find Full Text PDFThe differentiation and activation of macrophages are critical regulatory programs that are central to host inflammation and pathogen defense. However, the transcriptional regulatory pathways involved in these programs are not well understood. Herein, we demonstrate that the activity and expression of the transcription factor ATF2 is precisely regulated during primary human monocyte-to-macrophage differentiation and that its activation is linked to M1 polarization and antibacterial responses.
View Article and Find Full Text PDFCaloric restriction that promotes weight loss is an effective strategy for treating non-alcoholic fatty liver disease and improving insulin sensitivity in people with type 2 diabetes. Despite its effectiveness, in most individuals, weight loss is usually not maintained partly due to physiological adaptations that suppress energy expenditure, a process known as adaptive thermogenesis, the mechanistic underpinnings of which are unclear. Treatment of rodents fed a high-fat diet with recombinant growth differentiating factor 15 (GDF15) reduces obesity and improves glycaemic control through glial-cell-derived neurotrophic factor family receptor α-like (GFRAL)-dependent suppression of food intake.
View Article and Find Full Text PDFAm J Physiol Endocrinol Metab
August 2023
A person's metabolic rate corresponds to the whole body level sum of all oxidative reactions occurring on the cellular level. The energy expenditure (EE) can be categorized into various obligatory and facultative processes. In sedentary adults, basal metabolic rate is the largest contributor to total daily EE, and interindividual variability can be significant.
View Article and Find Full Text PDFNeurovascular abnormalities in mouse models of 16p11.2 deletion autism syndrome are reminiscent of alterations reported in murine models of glucose transporter deficiency, including reduced brain angiogenesis and behavioral alterations. Yet, whether cerebrovascular alterations in 16p11.
View Article and Find Full Text PDFBackground And Objectives: Coenzyme Q (CoQ) is an important electron carrier and antioxidant. The COQ7 enzyme catalyzes the hydroxylation of 5-demethoxyubiquinone-10 (DMQ), the second-to-last step in the CoQ biosynthesis pathway. We report a consanguineous family presenting with a hereditary motor neuropathy associated with a homozygous c.
View Article and Find Full Text PDFWe recently discovered that the expression of PRKN, a young-onset Parkinson disease-linked gene, confers redox homeostasis. To further examine the protective effects of parkin in an oxidative stress model, we first combined the loss of prkn with Sod2 haploinsufficiency in mice. Although adult prkn//Sod2 animals did not develop dopamine cell loss in the S.
View Article and Find Full Text PDFBackground: Mitochondrial dynamics (e.g. fission/fusion) play an important role in controlling chemoresistance in representative gynecologic malignancies, ovarian and cervical cancer.
View Article and Find Full Text PDFAm J Physiol Endocrinol Metab
May 2022
Obesity derives from an extended period of positive energy imbalance due to a complex interplay of environmental and biological factors. Muscle fiber type and physiology have been hypothesized to affect metabolism and energy expenditure and thus to affect an individual's propensity to gain weight. However, there have been conflicting reports regarding a relationship between muscle fiber type and obesity.
View Article and Find Full Text PDFNaked mole-rats are among the most hypoxia-tolerant mammals. During hypoxia, their body temperature (T) decreases via unknown mechanisms to conserve energy. In small mammals, non-shivering thermogenesis in brown adipose tissue (BAT) is critical to T regulation; therefore, we hypothesize that hypoxia decreases naked mole-rat BAT thermogenesis.
View Article and Find Full Text PDFMutations in susceptibility alleles correlate with gut-inflammatory diseases, such as Crohn's disease; however, this does not often impact the disease progression indicating the existence of compensatory genes. We show that a reduction in Foxo3a expression in IL-10-deficient mice results in a spontaneous and aggressive Crohn's- like disease with 100% penetrance, which is rescued by deletion of myeloid cells, T cells and inhibition of mTORC1. In Foxo3a IL-10 mice, there is poor cell death of myeloid cells in the gut, leading to increased accumulation of myeloid and T cells in the gut.
View Article and Find Full Text PDFMitochondrial disorders are a heterogeneous group of rare, degenerative multisystem disorders affecting the cell's core bioenergetic and signalling functions. Spontaneous improvement is rare. We describe a novel neonatal-onset mitochondriopathy in three infants with failure to thrive, hyperlactatemia, hyperammonemia, and apparent clinical resolution before 18 months.
View Article and Find Full Text PDFIn epithelial ovarian cancer (EOC), carboplatin/cisplatin-induced chemoresistance is a major hurdle to successful treatment. Aerobic glycolysis is a common characteristic of cancer. However, the role of glycolytic metabolism in chemoresistance and its impact on clinical outcomes in EOC are not clear.
View Article and Find Full Text PDF