Biology subjects

Pranay, A.

Publications and source records attributed to Pranay, A..

4 recordsLinked to original sources

bioRxiv2025

PFKFB2 is Pivotal for Metabolic Flexibility and Differential Glucose Utilization

BackgroundThe hearts constant energy demands make metabolic flexibility critical to its function as nutrient availability varies. The enzyme phosphofructokinase-2/fructose 2,6-bisphosphatase (PFKFB2) contributes to this flexibility by acting as a positive or negative regulator of cardiac glycolysis. We have previously shown that PFKFB2 is degraded in the diabetic heart and that a cardiac-specific PFKFB2 knockout (cKO) impacts ancillary glucose pathways and mitochondrial substrate preference. Therefore, defining PFKFB2s role in mitochondrial metabolic flexibility is paramount to understanding both metabolic homeostasis and metabolic syndromes. Further, it is unknown how PFKFB2 loss impacts the hearts response to acute stress. Here we examined how cardiac mitochondrial flexibility and the post-translational modification O-GlcNAcylation are affected in cKO mice in response to fasting or pharmacologic stimulation. MethodscKO and litter-matched controls (CON) were sacrificed in the fed or fasted (12 hours) states, with or without a 20 minute stimulant stress of caffeine and epinephrine. Mitochondrial respiration, metabolomics, and changes to systemic glucose homeostasis were evaluated. ResultscKO mice had moderate impairment in mitochondrial metabolic flexibility, affecting downstream glucose oxidation, respiration, and CPT1 activity. O-GlcNAcylation, a product of ancillary glucose metabolism, was upregulated in cKO hearts in the fed state, but this was ameliorated in the fasted state. Furthermore, metabolic remodeling in response to PFKFB2 loss was sufficient to impact circulating glucose in fasted and stressed states. ConclusionsPFKFB2 is essential for fed-to-fasted changes in cardiac metabolism and plays an important regulatory role in protein O-GlcNAcylation. Its loss also affects systemic glucose homeostasis under stressed conditions. Graphic Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=142 SRC="FIGDIR/small/656235v1_ufig1.gif" ALT="Figure 1000"> View larger version (50K): org.highwire.dtl.DTLVardef@158c873org.highwire.dtl.DTLVardef@1d0312eorg.highwire.dtl.DTLVardef@14ce8deorg.highwire.dtl.DTLVardef@4c4883_HPS_FORMAT_FIGEXP M_FIG C_FIG Research PerspectiveThis study raises and answers three key questions: how PFKFB2 contributes to cardiac mitochondrial metabolic flexibility, how post-prandial status regulates O-GlcNAcylation in a PFKFB2-dependent manner, and how altered cardiac glucose use impacts systemic glucose homeostasis under stress. These findings highlight a novel role for nutrient state in regulating cardiac metabolism, and especially O-GlcNAcylation, with PFKFB2 loss. Future studies should investigate whether reducing O-GlcNAcylation through fasting is sufficient to ameliorate pathological changes observed in the absence of PFKFB2.

biochemistry↗

bioRxiv2024

Mechanistic studies of PFKFB2 reveals a novel inhibitor of its kinase activity

The 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase (PFKFB) family of proteins are bifunctional enzymes that are of clinical relevance because of their roles in regulating glycolysis in insulin sensitive tissues and cancer. Here, we sought to express recombinant PFKFB2 and develop a robust protocol to measure its kinase activity. These studies resulted in the unexpected finding that bacterially expressed PFKFB2 is phosphorylated in situ on Ser483 but is not a result of autophosphorylation. Recombinant PFKFB2 was used to develop an enzymatic assay to test a library of molecules selected by the Atomwise AtomNet(R) AI platform. This resulted in the identification of a new inhibitor, B2, that inhibits PFKFB2 (IC50 3.29 M) and PFKFB3 (IC50 11.89 M). A-498 cells, which express both PFKFB2 and PFKFB3, were treated with B2. Seahorse XFe analysis revealed B2 inhibited cellular glycolysis and glycolytic capacity. Targeted LC/MS analysis showed B2 decreased fructose-1,6-bisphosphate and downstream glycolytic intermediates but increased fructose-6-phosphate levels, which is consistent with an inhibitory effect on PFK-1 activity. The LC/MS metabolic profile of A-498 cells treated under identical conditions with the known PFKFB3 inhibitor, PFK158, was distinct from that induced by B2. These results thus demonstrate the identification and validation of a new PFKFB kinase inhibitor.

biochemistry↗

bioRxiv2023

Loss of cardiac PFKFB2 drives Metabolic, Functional, and Electrophysiological Remodeling in the Heart

BackgroundPhosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2) is a critical glycolytic regulator responsible for upregulation of glycolysis in response to insulin and adrenergic signaling. PFKFB2, the cardiac isoform of PFK-2, is degraded in the heart in the absence of insulin signaling, contributing to diabetes-induced cardiac metabolic inflexibility. However, previous studies have not examined how the loss of PFKFB2 affects global cardiac metabolism and function. MethodsTo address this, we have generated a mouse model with a cardiomyocyte-specific knockout of PFKFB2 (cKO). Using 9-month-old cKO and control (CON) mice, we characterized impacts of PFKFB2 on cardiac metabolism, function, and electrophysiology. ResultscKO mice have a shortened lifespan of 9 months. Metabolically, cKO mice are characterized by increased glycolytic enzyme abundance and pyruvate dehydrogenase (PDH) activity, as well as decreased mitochondrial abundance and beta oxidation, suggesting a shift toward glucose metabolism. This was supported by a decrease in the ratio of palmitoyl carnitine to pyruvate-dependent mitochondrial respiration in cKO relative to CON animals. Metabolomic, proteomic, and western blot data support the activation of ancillary glucose metabolism, including pentose phosphate and hexosamine biosynthesis pathways. Physiologically, cKO animals exhibited impaired systolic function and left ventricular (LV) dilation, represented by reduced fractional shortening and increased LV internal diameter, respectively. This was accompanied by electrophysiological alterations including increased QT interval and other metrics of delayed ventricular conduction. ConclusionsLoss of PFKFB2 results in metabolic remodeling marked by cardiac ancillary pathway activation. This could delineate an underpinning of pathologic changes to mechanical and electrical function in the heart. Clinical PerspectiveO_ST_ABSWhat is New?C_ST_ABSO_LIWe have generated a novel cardiomyocyte-specific knockout model of PFKFB2, the cardiac isoform of the primary glycolytic regulator Phosphofructokinase-2 (cKO). C_LIO_LIThe cKO model demonstrates that loss of cardiac PFKFB2 drives metabolic reprogramming and shunting of glucose metabolites to ancillary metabolic pathways. C_LIO_LIThe loss of cardiac PFKFB2 promotes electrophysiological and functional remodeling in the cKO heart. C_LI What are the Clinical Implications?O_LIPFKFB2 is degraded in the absence of insulin signaling, making its loss particularly relevant to diabetes and the pathophysiology of diabetic cardiomyopathy. C_LIO_LIChanges which we observe in the cKO model are consistent with those often observed in diabetes and heart failure of other etiologies. C_LIO_LIDefining PFKFB2 loss as a driver of cardiac pathogenesis identifies it as a target for future investigation and potential therapeutic intervention. C_LI

physiology↗

bioRxiv2023

17α-estradiol Alleviates High-Fat Diet-Induced Inflammatory and Metabolic Dysfunction in Skeletal Muscle of Male and Female Mice

Skeletal muscle has a central role in maintaining metabolic homeostasis. 17-estradiol (17-E2), a naturally-occurring non-feminizing diastereomer of 17{beta}-estradiol that demonstrates efficacy for improving metabolic outcomes in male, but not female, mice. Despite several lines of evidence showing that 17-E2 treatment improves metabolic parameters in middle-aged obese and old male mice through effects in brain, liver, and white adipose tissue little is known about how 17-E2 alters skeletal muscle metabolism, and what role this may play in mitigating metabolic declines. Therefore, this study aimed to determine if 17-E2 treatment improves metabolic outcomes in skeletal muscle from obese male and female mice following chronic high fat diet (HFD) administration. We hypothesized that male, but not female, mice, would benefit from 17-E2 treatment during HFD. To test this hypothesis, we used a multi-omics approach to determine changes in lipotoxic lipid intermediates, metabolites, and proteins related to metabolic homeostasis. In male mice, we show that 17-E2 alleviates HFD-induced metabolic detriments of skeletal muscle by reducing the accumulation of diacylglycerol (DAGs) and ceramides, inflammatory cytokine levels, and reduced the abundance of most of the proteins related to lipolysis and beta-oxidation. In contrast to males, 17-E2 treatment in female mice had little effect on the DAGs and ceramides content, muscle inflammatory cytokine levels, or changes to the relative abundance of proteins involved in beta-oxidation. These data support to the growing evidence that 17-E2 treatment could be beneficial for overall metabolic health in male mammals.

physiology↗