Biology subjects

Jurczak, M. J.

Publications and source records attributed to Jurczak, M. J..

12 recordsLinked to original sources

bioRxiv2025

Adropin protects against cardiac metabolic remodeling and dysfunction in HFpEF

Cardiometabolic heart failure with preserved ejection fraction (HFpEF) is a heterogenous metabolic disease, which in the heart presents as left ventricle diastolic dysfunction, ventricular stiffness, and myocardial structural remodeling. Deleterious changes in cardiac metabolism are central to HFpEF pathophysiology, and proposed treatments for the disease have focused on repairing these defects. In this study, we used a preclinical mouse model that recapitulates cardiometabolic HFpEF to elucidate the molecular mechanisms driving cardiac dysfunction, and tested whether recombinant Adropin (a liver- and brain-derived endogenous peptide hormone) could reverse observed defects. We show that long-term treatment with Adropin reversed multiple markers of HFpEF-related cardiac dysfunction (including fibrosis, diastolic dysfunction, and cardiomyocyte hypertrophy). Using untargeted metabolomics, we found that Adropin treatment reduced hexosamine biosynthesis pathway activity, leading to a reduction in the O-GlcNAcylation of the cardiac fatty acid oxidation enzyme long chain acyl-CoA dehydrogenase (LCAD). Reducing LCAD O-GlcNAcylation increased LCAD activity in vitro, and reduced the accumulation of long-chain acylcarnitines in HFpEF mouse hearts in vivo. Our results suggest that Adropin may restore cardiac metabolic function in HFpEF, and that targeting this pathway may be a novel therapeutic avenue for this disease. CLINICAL PERSPECTIVE- Adropin is a circulating liver- and brain-derived peptide that regulates energy metabolism in the heart and other high metabolic-demand tissues. The plasma abundance of Adropin is decreased in diabetic, hypertensive, and aged individuals; all comorbid risk factors for the development of heart failure with preserved ejection (HFpEF). We therefore examined the potential role of Adropin in HFpEF pathophysiology. - Patients with HFpEF display significant reductions in circulating Adropin levels, matching those seen in comorbid diseases. In a mouse model of HFpEF, treatment with recombinant Adropin reduced diastolic dysfunction, cardiac fibrosis, and cardiomyocyte hypertrophy. - These data suggest that targeting the Adropin pathway may represent a new therapeutic approach in HFpEF.

physiology↗

bioRxiv2025

Cardiac-specific deletion of GCN5L1 promotes fatty liver disease in HFpEF

The prevalence of cardiometabolic heart failure with preserved ejection fraction (HFpEF) continues to grow, representing over half of heart failure cases in the United States. As no specific medication for HFpEF exists, treatment guidelines focus on the management of comorbidities related to metabolic syndrome (e.g. obesity, diabetes, hypertension) that promote the disease1. These same comorbidities also drive pathology in non-cardiac tissues, and the links between cardiometabolic disease presentations in different organs are increasingly being recognized. Preclinical studies on the potential crosstalk between HFpEF and metabolic disease in the liver (e.g. metabolic dysfunction-associated liver disease; MASLD) have focused on how liver dysfunction may affect the heart, particularly through the release of secreted liver proteins. This may reflect the situation in the clinic, where incident MASLD is a risk factor for future HFpEF development. Here, in contrast to this developing paradigm of liver-initiated cardiac disease, we report for the first time a defect in cardiac metabolism related to the mitochondrial metabolic protein GCN5L1 that drives hepatic steatosis and MASLD in HFpEF.

physiology↗

bioRxiv2024

Epigenetic regulation of global proteostasis dynamics by RBBP5 ensures mammalian organismal health

Proteostasis is vital for cellular health, with disruptions leading to aging, neurodegeneration and metabolic disorders. Traditionally, proteotoxic stress responses were studied as acute reactions to various noxious factors; however, recent evidence reveals that many proteostasis genes exhibit [~]12h ultradian rhythms under physiological conditions in mammals, driven by an XBP1s-dependent 12h oscillator. By examining the chromatin landscape of this oscillator, we identified RBBP5 as an essential epigenetic regulator of global proteostasis dynamics. Mechanistically, as the core subunit of the SET1/COMPASS complex, RBBP5 co-activates XBP1s to facilitate dynamic proteostasis gene expression by marking promoter-proximal H3K4me3, which further recruits the Integrator Complex and SWI/SNF chromatin remodelers. Functionally, RBBP5 is indispensable for regulating both the 12h oscillator and acute transcriptional response to various proteotoxic stresses, including ER stress and nutrient deprivation. RBBP5 ablation causes increased susceptibility to proteotoxic stress, chronic inflammation, and hepatic steatosis in mice, along with impaired autophagy and reduced cell survival in vitro. In humans, lower RBBP5 expression is associated with reduced adaptive stress-response gene expression and hepatic steatosis. Our findings not only highlight a previously unrecognized epigenetic timing mechanism distinct from circadian regulation but also establish RBBP5 as a central regulator of proteostasis, essential for cellular resilience and organismal health. One sentence summaryRBBP5 regulates global mammalian proteostasis.

cell biology↗

bioRxiv2023

Mineralocorticoid receptor-independent activation of ENaC in bile duct ligated mice

Sodium and fluid retention in liver disease is classically thought to result from reduced effective circulating volume and stimulation of the renin-angiotensin-aldosterone system (RAAS). Aldosterone dives Na+ retention by activating the mineralocorticoid receptor and promoting the maturation and apical surface expression of the epithelial Na+ channel (ENaC), found in the aldosterone-sensitive distal nephron. However, evidence of fluid retention without RAAS activation suggests the involvement of additional mechanisms. Liver disease can greatly increase plasma and urinary bile acid concentrations and have been shown to activate ENaC in vitro. We hypothesize that elevated bile acids in liver disease activate ENaC and drive fluid retention independent of RAAS. We therefore increased circulating bile acids in mice through bile duct ligation (BDL) and measured effects on urine and body composition, while using spironolactone to antagonize the mineralocorticoid receptor. We found BDL lowered blood [K+] and hematocrit, and increased benzamil-sensitive natriuresis compared to sham, consistent with ENaC activation. BDL mice also gained significantly more body water. Blocking ENaC reversed fluid gains in BDL mice but had no effect in shams. In isolated collecting ducts from rabbits, taurocholic acid stimulated net Na+ absorption but had no effect on K+ secretion or flow-dependent ion fluxes. Our results provide experimental evidence for a novel aldosterone-independent mechanism for sodium and fluid retention in liver disease which may provide additional therapeutic options for liver disease patients. SignificanceAdvanced liver disease is often complicated by renal sodium retention, leading to fluid retention, poor outcomes, and increased mortality. This is currently thought to be driven by increased levels of the hormone aldosterone, although numerous published reports demonstrate normal aldosterone levels in many liver patients with volume overload. Management of these patients relies on diuretics and Na+ restriction, or more invasive procedures with increased risks for diuretic-resistant patients. Here, we report a novel mechanism for fluid retention in liver disease, which provides a basis to develop new strategies to treat fluid retention in these patients.

physiology↗

bioRxiv2022

Reduced acetylation of TFAM promotes bioenergetic dysfunction in the failing heart

General Control of Amino-Acid Synthesis 5-like 1 (GCN5L1) was previously identified as a key regulator of protein lysine acetylation in mitochondria. Subsequent studies demonstrated that GCN5L1 regulates the acetylation status and activity of mitochondrial fuel substrate metabolism enzymes. However, the role of GCN5L1 in response to chronic hemodynamic stress is largely unknown. Here, we show that cardiomyocyte-specific GCN5L1 knockout mice (cGCN5L1 KO) display exacerbated pressure overload-induced heart failure progression following transaortic constriction (TAC). Mitochondrial DNA and mitochondrial electron transport chain protein levels were decreased in cGCN5L1 KO hearts after TAC, and isolated neonatal cardiomyocytes with reduced GCN5L1 expression had lower bioenergetic output in response to hypertrophic stress. Loss of GCN5L1 expression led to a decrease in the acetylation status of mitochondrial transcription factor A (TFAM) after TAC in vivo, which was linked to a reduction in mtDNA levels in vitro. Together, these data suggest that GCN5L1 may protect from hemodynamic stress by maintaining mitochondrial bioenergetic output. HighlightsO_LIReduced GCN5L1 expression in the failing heart promotes contractile dysfunction C_LIO_LIMitochondrial DNA (mtDNA) levels are reduced in cardiomyocyte-specific GCN5L1 knockout mice following hemodynamic stress C_LIO_LIGCN5L1 knockdown reduces, and GCN5L1 overexpression increases, bioenergetic output in hypertrophic cardiomyocytes C_LIO_LIGCN5L1-mediated acetylation of TFAM promotes increased mtDNA levels C_LI

physiology↗

bioRxiv2022

G-PROTEIN COUPLED RECEPTOR 19 (GPR19) KNOCKOUT MICE DISPLAY SEX-DEPENDENT METABOLIC DYSFUNCTION

G-protein coupled receptors (GPCRs) mediate signal transduction from the cellular surface to intracellular metabolic pathways. While the function of many GPCRs has been delineated previously, a significant number require further characterization to elucidate their cellular function. G-protein coupled receptor 19 (GPR19) is a poorly characterized class A GPCR which has been implicated in the regulation of circadian rhythm, tumor metastasis, and mitochondrial homeostasis. In this report, we use a novel knockout (KO) mouse model to examine the role of GPR19 in whole-body metabolic regulation. We show that loss of GPR19 promotes increased energy expenditure and decreased activity in both male and female mice. However, only male GPR19 KO mice display glucose intolerance in response to a high fat diet (HFD). Loss of GPR19 expression in male mice, but not female mice, resulted in diet-induced hepatomegaly, which was associated with decreased expression of key fatty acid oxidation genes in male GPR19 KO livers. Overall, our data suggest that loss of GPR19 impacts whole-body energy metabolism in diet-induced obese mice in a sex-dependent manner.

physiology↗

bioRxiv2021

Diet-induced obese mice are resistant to improvements in cardiac function resulting from short-term adropin treatment

Previous studies have shown that treatment with recombinant adropin, a circulating peptide secreted by the liver and brain, restores glucose utilization in the hearts of diet-induced obese mice. This restoration of fuel substrate flexibility, which is lost in obese and diabetic animals, has the potential to improve contractile function in the diabetic heart. Using an ex vivo approach, we examined whether short-term adropin treatment could enhance cardiac function in a mouse model of diet-induced obesity. Our study showed that acute adropin treatment reduces inhibitory phosphorylation of pyruvate dehydrogenase in primary neonatal cardiomyocytes, and leads to moderate improvements in ex vivo cardiac function in mice fed a low fat diet. Conversely, short-term exposure to adropin led to a small decrease in cardiac function in mice fed a long-term high fat diet. Insulin treatment did not significantly alter cardiac function in adropin treated hearts from either low or high fat diet mice, however acute adropin treatment did moderately restore downstream insulin signaling in high fat diet fed mice. Overall, these data suggest that in an ex vivo setting, acute adropin treatment alone is not sufficient to promote improved cardiac function in obese animals.

physiology↗

bioRxiv2021

Inhibitory Acetylation of Pyruvate Dehydrogenase Promotes Diastolic Dysfunction in Mice

Left ventricular diastolic dysfunction is a structural and functional condition that precedes the development of heart failure with preserved ejection fraction (HFpEF). The etiology of diastolic dysfunction includes alterations in fuel substrate metabolism that negatively impact cardiac bioenergetics, and may precipitate the eventual transition to heart failure. To date, the molecular mechanisms that regulate early changes in fuel metabolism leading to diastolic dysfunction remain unclear. In this report, we use a diet-induced obesity model and quantitative acetylproteomics in aged mice to show that inhibitory lysine acetylation of the pyruvate dehydrogenase (PDH) complex promotes energetic deficits and diastolic dysfunction in mouse hearts. Cardiomyocyte-specific deletion of the mitochondrial lysine acetylation regulatory protein GCN5L1 prevented hyperacetylation of the PDH complex subunit PDHA1, allowing aged obese mice to continue using pyruvate as a bioenergetic substrate in the heart. Our findings suggest that changes in mitochondrial protein lysine acetylation represent a key metabolic component of diastolic dysfunction that precedes the development of heart failure.

physiology↗

bioRxiv2019

Blimp-1 in adipose resident Tregs controls adipocyte beiging and obesity

Crosstalk between the immune system and adipocytes is critical for maintaining tissue homeostasis and regulating chronic systemic inflammation during diet-induced obesity (DIO). How visceral adipose tissue resident regulatory T cells (aTregs) signal to adipocytes in the visceral adipose tissue (VAT) is not understood. Here we show that Treg-specific ablation of the transcriptional regulator Blimp-1 resulted in increased insulin sensitivity, decreased body weight and increased Ucp-1 in adipocytes in high fat diet (HFD)-fed mice. Mechanistically, we demonstrate that Blimp-1 drives IL-10 production in Tregs, thus suppressing beiging and energy expenditure in adipocytes. Moreover, IL-10 mRNA expression positively correlated with increasing body weight in humans. These findings reveal a surprising relationship between aTregs and adipocytes in promoting insulin resistance during excessive caloric intake, placing Blimp-1-regulated IL-10 expression by aTregs at a critical juncture in the development of obesity and its associated comorbidities in mice and humans. SUMMARYHere we show that ablation of Blimp-1 in adipose tissue resident Tregs (aTregs) leads to decreased IL-10 production, resulting in increased Ucp-1 expression and beiging by adipocytes and protection from diet-induced obesity and insulin resistance.

immunology↗

bioRxiv2019

A big-data approach to understanding metabolic rate and response to obesity in laboratory mice

Maintaining a healthy body weight requires an exquisite balance between energy intake and energy expenditure. In humans and in laboratory mice these factors are experimentally measured by powerful and sensitive indirect calorimetry devices. To understand the genetic and environmental factors that contribute to the regulation of body weight, an important first step is to establish the normal range of metabolic values and primary sources contributing to variability in results. Here we examine indirect calorimetry results from two experimental mouse projects, the Mouse Metabolic Phenotyping Centers and International Mouse Phenotyping Consortium to develop insights into large-scale trends in mammalian metabolism. Analysis of nearly 10,000 wildtype mice revealed that the largest experimental variances are consequences of institutional site. This institutional effect on variation eclipsed those of housing temperature, body mass, locomotor activity, sex, or season. We do not find support for the claim that female mice have greater metabolic variation than male mice. An analysis of these factors shows a normal distribution for energy expenditure in the phenotypic analysis of 2,246 knockout strains and establishes a reference for the magnitude of metabolic changes. Using this framework, we examine knockout strains with known metabolic phenotypes. We compare these effects with common environmental challenges including age, and exercise. We further examine the distribution of metabolic phenotypes exhibited by knockout strains of genes corresponding to GWAS obesity susceptibility loci. Based on these findings, we provide suggestions for how best to design and conduct energy balance experiments in rodents, as well as how to analyze and report data from these studies. These recommendations will move us closer to the goal of a centralized physiological repository to foster transparency, rigor and reproducibility in metabolic physiology experimentation.

physiology↗

bioRxiv2019

The transcriptional regulator Id2 is critical for adipose-resident regulatory T cell differentiation, survival and function

Adipose regulatory T cells (aTregs) have emerged as critical cells for the control of local and systemic inflammation. In this study, we show a distinctive role for the transcriptional regulator Id2 in the differentiation, survival and function of aTregs. Id2 was highly expressed in aTregs compared with high Id3 expression in lymphoid Tregs. Treg-specific deletion of Id2 resulted in a substantial decrease in aTregs, while Tregs in the spleen and lymph nodes were unaffected. Additionally, loss of Id2 resulted in decreased expression of aTreg associated markers including ST2, CCR2, KLRG1 and GATA3. Gene expression analysis revealed that Id2 expression was essential for the survival of aTregs and loss of Id2 increased cell death in aTregs due to increased Fas expression. Id2-mediated aTreg depletion resulted in increased systemic inflammation, increased inflammatory macrophages and CD8+ effector T cells and loss of glucose tolerance under standard diet conditions. Thus, we reveal an unexpected and novel function for Id2 in mediating differentiation, survival and function of adipose-resident Tregs, that when lost resulting in increased metabolic perturbation.

immunology↗

bioRxiv2018

Petite Integration Factor 1 (PIF1) helicase deficiency increases weight gain in Western diet-fed female mice without increased inflammatory markers or decreased glucose clearance

Petite Integration Factor 1 (PIF1) is a multifunctional helicase present in nuclei and mitochondria. PIF1 knock out (KO) mice exhibit accelerated weight gain and decreased wheel running on a normal chow diet. In the current study, we investigated whether Pif1 removal alters whole body metabolism in response to weight gain. PIF1 KO and wild type (WT) C57BL/6J mice were fed a Western diet (WD) rich in fat and carbohydrates before evaluation of their metabolic phenotype. Compared with weight gain-resistant WT female mice, WD-fed PIF1 KO females, but not males, showed accelerated adipose deposition, decreased locomotor activity, and reduced whole-body energy expenditure without increased dietary intake. Surprisingly, PIF1 KO females were protected against obesity-induced alterations in fasting blood glucose and glucose clearance. WD-fed PIF1 KO females developed mild hepatic steatosis and associated changes in liver gene expression that were absent in weight-matched, WD-fed female controls, linking hepatic steatosis to Pif1 ablation rather than increased body weight. WD-fed PIF1 KO females also showed decreased gene expression of inflammatory markers in adipose tissue. Collectively, these data separated weight gain from inflammation and impaired glucose homeostasis. They also support a role for Pif1 in weight gain resistance and liver metabolic dysregulation during nutrient stress.

physiology↗