Browsing by Author "Craige, Siobhan M."

Now showing 1 - 7 of 7
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    Exercise Rescues Gene Pathways Involved in Vascular Expansion and Promotes Functional Angiogenesis in Subcutaneous White Adipose Tissue
    Min, So Yun; Learnard, Heather; Kant, Shashi; Gealikman, Olga; Rojas-Rodriguez, Raziel; DeSouza, Tiffany; Desai, Anand; Keaney, John F.; Corvera, Silvia; Craige, Siobhan M. (MDPI, 2019-04-25)
    Exercise mitigates chronic diseases such as diabetes, cardiovascular diseases, and obesity; however, the molecular mechanisms governing protection from these diseases are not completely understood. Here we demonstrate that exercise rescues metabolically compromised high fat diet (HFD) fed mice, and reprograms subcutaneous white adipose tissue (scWAT). Using transcriptomic profiling, scWAT was analyzed for HFD gene expression changes that were rescued by exercise. Gene networks involved in vascularization were identified as prominent targets of exercise, which led us to investigate the vasculature architecture and endothelial phenotype. Vascular density in scWAT was found to be compromised in HFD, and exercise rescued this defect. Similarly, angiogenic capacity as measured by ex vivo capillary sprouting was significantly promoted with exercise. Together, these data demonstrate that exercise enhances scWAT vascularization and functional capacity for angiogenesis, and can prevent the detrimental effects of HFD. The improvement in these indices correlates with improvement of whole-body metabolism, suggesting that scWAT vascularization may be a potential therapeutic target for metabolic disease.
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    JNK and cardiometabolic dysfunction
    Craige, Siobhan M.; Chen, Kai; Blanton, Robert M.; Keaney, John F.; Kant, Shashi (Portland Press, 2019-07-19)
    Cardiometabolic syndrome (CMS) describes the cluster of metabolic and cardiovascular diseases that are generally characterized by impaired glucose tolerance, intra-abdominal adiposity, dyslipidemia, and hypertension. CMS currently affects more than 25% of the world's population and the rates of diseases are rapidly rising. These CMS conditions represent critical risk factors for cardiovascular diseases including atherosclerosis, heart failure, myocardial infarction, and peripheral artery disease (PAD). Therefore, it is imperative to elucidate the underlying signaling involved in disease onset and progression. The c-Jun N-terminal Kinases (JNKs) are a family of stress signaling kinases that have been recently indicated in CMS. The purpose of this review is to examine the in vivo implications of JNK as a potential therapeutic target for CMS. As the constellation of diseases associated with CMS are complex and involve multiple tissues and environmental triggers, carefully examining what is known about the JNK pathway will be important for specificity in treatment strategies.
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    Liver macrophages inhibit the endogenous antioxidant response in obesity-associated insulin resistance
    Azzimato, Valerio; Jager, Jennifer; Chen, Ping; Morgantini, Cecilia; Levi, Laura; Barreby, Emelie; Sulen, Andre; Oses, Carolina; Willerbrords, Joost; Xu, Connie; Li, Xidan; Shen, Joanne X.; Akbar, Naveed; Haag, Lars; Ellis, Ewa; Wålhen, Kerstin; Näslund, Erik; Thorell, Anders; Choudhury, Robin P.; Lauschke, Volker M.; Rydén, Mikael; Craige, Siobhan M.; Aouadi, Myriam (2020-02-26)
    Obesity and insulin resistance are risk factors for nonalcoholic fatty liver disease (NAFLD), the most common chronic liver disease worldwide. Because no approved medication nor an accurate and noninvasive diagnosis is currently available for NAFLD, there is a clear need to better understand the link between obesity and NAFLD. Lipid accumulation during obesity is known to be associated with oxidative stress and inflammatory activation of liver macrophages (LMs). However, we show that although LMs do not become proinflammatory during obesity, they display signs of oxidative stress. In livers of both humans and mice, antioxidant nuclear factor erythroid 2– related factor 2 (NRF2) was down-regulated with obesity and insulin resistance, yielding an impaired response to lipid accumulation. At the molecular level, a microRNA-targeting NRF2 protein, miR-144, was elevated in the livers of obese insulin-resistant humans and mice, and specific silencing of miR-144 in murine and human LMs was sufficient to restore NRF2 protein expression and the antioxidant response. These results highlight the pathological role of LMs and their therapeutic potential to restore the impaired endogenous antioxidant response in obesity-associated NAFLD.
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    Neural JNK3 regulates blood flow recovery after hindlimb ischemia in mice via an Egr1/Creb1 axis
    Kant, Shashi; Craige, Siobhan M.; Chen, Kai; Reif, Michaella M.; Learnard, Heather; Kelly, Mark; Caliz, Amada D.; Tran, Khanh-Van; Ramo, Kasmir; Peters, Owen M.; Freeman, Marc; Davis, Roger J.; Keaney, John F. Jr. (Springer Nature, 2019-09-17)
    Diseases related to impaired blood flow such as peripheral artery disease (PAD) impact nearly 10 million people in the United States alone, yet patients with clinical manifestations of PAD (e.g., claudication and limb ischemia) have limited treatment options. In ischemic tissues, stress kinases such as c-Jun N-terminal kinases (JNKs), are activated. Here, we show that inhibition of the JNK3 (Mapk10) in the neural compartment strikingly potentiates blood flow recovery from mouse hindlimb ischemia. JNK3 deficiency leads to upregulation of growth factors such as Vegfa, Pdgfb, Pgf, Hbegf and Tgfb3 in ischemic muscle by activation of the transcription factors Egr1/Creb1. JNK3 acts through Forkhead box O3 (Foxo3a) to suppress the activity of Egr1/Creb1 transcription regulators in vitro. In JNK3-deficient cells, Foxo3a is suppressed which leads to Egr1/Creb1 activation and upregulation of downstream growth factors. Collectively, these data suggest that the JNK3-Foxo3a-Egr1/Creb1 axis coordinates the vascular remodeling response in peripheral ischemia.
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    Neuromuscular Dysfunction Precedes Cognitive Impairment in a Mouse Model of Alzheimer's Disease
    Brisendine, Matthew H.; Nichenko, Anna S.; Bandara, Aloka B.; Willoughby, Orion S.; Amiri, Niloufar; Weingrad, Zach; Specht, Kalyn S.; Bond, Jacob M.; Addington, Adele; Jones III, Ronald G.; Murach, Kevin A.; Poelzing, Steven; Craige, Siobhan M.; Grange, Robert W.; Drake, Joshua C. (Oxford University Press, 2023-12-04)
    Alzheimer's disease (AD) develops along a continuum that spans years prior to diagnosis. Decreased muscle function and mitochondrial respiration occur years earlier in those that develop AD; however, it is unknown what causes these peripheral phenotypes in a disease of the brain. Exercise promotes muscle, mitochondria, and cognitive health and is proposed to be a potential therapeutic for AD, but no study has investigated how skeletal muscle adapts to exercise training in an AD-like context. Utilizing 5xFAD mice, an AD model that develops ad-like pathology and cognitive impairments around 6 mo of age, we examined in vivo neuromuscular function and exercise adapations (mitochondrial respiration and RNA sequencing) before the manifestation of overt cognitive impairment. We found 5xFAD mice develop neuromuscular dysfunction beginning as early as 4 mo of age, characterized by impaired nerve-stimulated muscle torque production and compound nerve action potential of the sciatic nerve. Furthermore, skeletal muscle in 5xFAD mice had altered, sex-dependent, adaptive responses (mitochondrial respiration and gene expression) to exercise training in the absence of overt cognitive impairment. Changes in peripheral systems, specifically neural communication to skeletal muscle, may be harbingers for AD and have implications for lifestyle interventions, like exercise, in AD.
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    Nox4 mediates skeletal muscle metabolic responses to exercise
    Specht, Kalyn S.; Kant, Shashi; Addington, Adele K.; McMillan, Ryan P.; Hulver, Matthew W.; Learnard, Heather; Campbell, Maura; Donnelly, Sarah R.; Caliz, Amada D.; Pei, Yongmei; Reif, Michaella M.; Bond, Jacob M.; DeMarco, Anthony; Craige, Branch; Keaney, John F. Jr.; Craige, Siobhan M. (2021-03)
    Objective: The immediate signals that couple exercise to metabolic adaptations are incompletely understood. Nicotinamide adenine dinucleotide phosphate oxidase 4 (Nox4) produces reactive oxygen species (ROS) and plays a significant role in metabolic and vascular adaptation during stress conditions. Our objective was to determine the role of Nox4 in exercise-induced skeletal muscle metabolism. Methods: Mice were subjected to acute exercise to assess their immediate responses. mRNA and protein expression responses to Nox4 and hydrogen peroxide (H2O2) were measured by qPCR and immunoblotting. Functional metabolic flux was measured via ex vivo fatty acid and glucose oxidation assays using C-14-labeled palmitate and glucose, respectively. A chronic exercise regimen was also utilized and the time to exhaustion along with key markers of exercise adaptation (skeletal muscle citrate synthase and beta-hydroxyacyl-coA-dehydrogenase activity) were measured. Endothelial-specific Nox4-deficient mice were then subjected to the same acute exercise regimen and their subsequent substrate oxidation was measured. Results: We identified key exercise-responsive metabolic genes that depend on H2O2 and Nox4 using catalase and Nox4-deficient mice. Nox4 was required for the expression of uncoupling protein 3 (Ucp3), hexokinase 2 (Hk2), and pyruvate dehydrogenase kinase 4 (Pdk4), but not the expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (Pgc-1 alpha). Global Nox4 deletion resulted in decreased UCP3 protein expression and impaired glucose and fatty acid oxidization in response to acute exercise. Furthermore, Nox4-deficient mice demonstrated impaired adaptation to chronic exercise as measured by the time to exhaustion and activity of skeletal muscle citrate synthase and beta-hydroxyacyl-coA-dehydrogenase. Importantly, mice deficient in endothelial-Nox4 similarly demonstrated attenuated glucose and fatty acid oxidation following acute exercise. Conclusions: We report that H2O2 and Nox4 promote immediate responses to exercise in skeletal muscle. Glucose and fatty acid oxidation were blunted in the Nox4-deficient mice post-exercise, potentially through regulation of UCP3 expression. Our data demonstrate that endothelial-Nox4 is required for glucose and fatty acid oxidation, suggesting inter-tissue cross-talk between the endothelium and skeletal muscle in response to exercise. (C) 2021 The Authors. Published by Elsevier GmbH.
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    Sensing local energetics to acutely regulate mitophagy in skeletal muscle
    Nichenko, Anna S.; Specht, Kalyn S.; Craige, Siobhan M.; Drake, Joshua C. (Frontiers, 2022-08-29)
    The energetic requirements of skeletal muscle to sustain movement, as during exercise, is met largely by mitochondria, which form an intricate, interconnected reticulum. Maintenance of a healthy mitochondrial reticulum is essential for skeletal muscle function, suggesting quality control pathways are spatially governed. Mitophagy, the process by which damaged and/or dysfunctional regions of the mitochondrial reticulum are removed and degraded, has emerged as an integral part of the molecular response to exercise. Upregulation of mitophagy in response to acute exercise is directly connected to energetic sensing mechanisms through AMPK. In this review, we discuss the connection of mitophagy to muscle energetics and how AMPK may spatially control mitophagy through multiple potential means.