Biology subjects

Latimer, H.

Publications and source records attributed to Latimer, H..

4 recordsLinked to original sources

bioRxiv2024

The human glucocorticoid receptor variant rs6190 promotes blood cholesterol and atherosclerosis

Elevated cholesterol poses cardiovascular risks. The glucocorticoid receptor (GR) harbors a still undefined role in cholesterol regulation. Here, we report that a coding single nucleotide polymorphism (SNP) in the gene encoding the GR, rs6190, associated with increased cholesterol in women according to UK Biobank and All Of Us datasets. In SNP-genocopying mice, we found that the SNP enhanced hepatic GR activity to transactivate Pcsk9 and Bhlhe40, negative regulators of low-density lipoprotein (LDL) and high-density lipoprotein (HDL) receptors respectively. In mice, the SNP was sufficient to elevate circulating cholesterol across all lipoprotein fractions and the risk and severity of atherosclerotic lesions on the pro-atherogenic hAPOE*2/*2 background. The SNP effect on atherosclerosis was blocked by in vivo liver knockdown of Pcsk9 and Bhlhe40. Also, corticosterone and tes-tosterone were protective against the mutant GR program in cholesterol and atherosclerosis in male mice, while the SNP effect was additive to estrogen loss in females. Remarkably, we found that the mutant GR program was conserved in human hepatocyte-like cells using CRISPR-engineered, SNP-genocopying human induced pluripotent stem cells (hiPSCs). Taken together, our study leverages a non-rare human variant to uncover a novel GR-dependent mechanism contributing to atherogenic risk, particularly in women. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=106 SRC="FIGDIR/small/625727v2_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@158e895org.highwire.dtl.DTLVardef@d9a2corg.highwire.dtl.DTLVardef@104e6bcorg.highwire.dtl.DTLVardef@c87160_HPS_FORMAT_FIGEXP M_FIG C_FIG

physiology↗

bioRxiv2024

The human genetic variant rs6190 unveils Foxc1 and Arid5a as novel pro-metabolic targets of the glucocorticoid receptor in muscle.

The genetic determinants of the glucocorticoid receptor (GR) metabolic action remain largely unelucidated. This is a compelling gap in knowledge for the GR single nucleotide polymorphism (SNP) rs6190 (p.R23K), which has been associated in humans with enhanced metabolic health but whose mechanism of action remains completely unknown. We generated transgenic knock-in mice genocopying this polymorphism to elucidate how the mutant GR impacts metabolism. Compared to non-mutant littermates, mutant mice showed increased insulin sensitivity on regular chow and high-fat diet, blunting the diet-induced adverse effects on adiposity and exercise intolerance. Overlay of RNA-seq and ChIP-seq profiling in skeletal muscle revealed increased transactivation of Foxc1 and Arid5A genes by the mutant GR. Using myotropic adeno-associated viruses for in vivo overexpression or knockdown in muscle, we found that Foxc1 was required and sufficient for normal expression levels of insulin response pathway genes Insr and Irs1, promoting muscle insulin sensitivity. In parallel, Arid5a was required and sufficient to transcriptionally repress the lipid uptake genes C 36 and Fabp4, reducing muscle triacylglycerol accumulation. Moreover, the Foxc1 and Arid5a programs in muscle were divergently changed by glucocorticoid regimens with opposite metabolic outcomes in muscle. Finally, we found a direct human relevance for our mechanism of SNP action in the UK Biobank and All of Us datasets, where the rs6190 SNP correlated with pro-metabolic changes in BMI, lean mass, strength and glucose control according to zygosity. Collectively, our study leveraged a human nuclear receptor coding variant to unveil novel epigenetic regulators of muscle metabolism. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=150 HEIGHT=200 SRC="FIGDIR/small/586997v2_ufig1.gif" ALT="Figure 1"> View larger version (50K): org.highwire.dtl.DTLVardef@1af900borg.highwire.dtl.DTLVardef@119dcaforg.highwire.dtl.DTLVardef@e78baeorg.highwire.dtl.DTLVardef@1835427_HPS_FORMAT_FIGEXP M_FIG C_FIG

physiology↗

bioRxiv2023

Light-phase prednisone promotes glucose oxidation in heart through novel transactivation targets of cardiomyocyte-specific GR and KLF15

Circadian time-of-intake gates the cardioprotective effects of glucocorticoid administration in both healthy and infarcted hearts. The cardiomyocyte-specific glucocorticoid receptor (GR) and its co-factor, Kruppel-like factor (Klf15), play critical roles in maintaining normal heart function in the long-term and serve as pleiotropic regulators of cardiac metabolism. Despite this understanding, the cardiomyocyte-autonomous metabolic targets influenced by the concerted epigenetic action of GR-Klf15 axis remain undefined. Here, we demonstrate the critical roles of the cardiomyocyte-specific GR and Klf15 in orchestrating a circadian-dependent glucose oxidation program within the heart. Combining integrated transcriptomics and epigenomics with cardiomyocyte-specific inducible ablation of GR or Klf15, we identified their synergistic role in the activation of adiponectin receptor expression (Adipor1) and the mitochondrial pyruvate complex (Mpc1/2), thereby enhancing insulin-stimulated glucose uptake and pyruvate oxidation. Furthermore, in obese diabetic (db/db) mice exhibiting insulin resistance and impaired glucose oxidation, light-phase prednisone administration, as opposed to dark-phase prednisone dosing, effectively restored cardiomyocyte glucose oxidation and improved diastolic function towards control-like levels in a sex-independent manner. Collectively, our findings uncover novel cardiomyocyte-autonomous metabolic targets of the GR-Klf15 axis. This study highlights the circadian-dependent cardioprotective effects of glucocorticoids on cardiomyocyte glucose metabolism, providing critical insights into chrono-pharmacological strategies for glucocorticoid therapy in cardiovascular disease. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=63 SRC="FIGDIR/small/572210v3_ufig1.gif" ALT="Figure 1"> View larger version (19K): org.highwire.dtl.DTLVardef@cf4b3corg.highwire.dtl.DTLVardef@1547db1org.highwire.dtl.DTLVardef@7f85aorg.highwire.dtl.DTLVardef@141fe94_HPS_FORMAT_FIGEXP M_FIG C_FIG Brief summaryDepending on when it is taken during the day, the drug prednisone activates the heart to

physiology↗

bioRxiv2023

Glucocorticoid intermittence coordinates rescue of energy and mass in aging-related sarcopenia through the myocyte-autonomous PGC1alpha-Lipin1 transactivation

Sarcopenia burdens the elderly population through loss of muscle energy and mass, yet treatments to functionally rescue both parameters are missing. The glucocorticoid prednisone remodels muscle metabolism based on frequency of intake, but its mechanisms in sarcopenia are unknown. We found that once-weekly intermittent prednisone rescued muscle quality in aged 24-month-old mice to levels comparable to young 4-month-old mice. We discovered an age- and sex-independent glucocorticoid receptor transactivation program in muscle encompassing PGC1alpha and its co-factor Lipin1. Treatment coordinately improved mitochondrial abundance through isoform 1 and muscle mass through isoform 4 of the myocyte-specific PGC1alpha, which was required for the treatment-driven increase in carbon shuttling from glucose oxidation to amino acid biogenesis. We also probed the myocyte-specific Lipin1 as non-redundant factor coaxing PGC1alpha upregulation to the stimulation of both oxidative and anabolic capacities. Our study unveils an aging-resistant druggable program in myocytes to coordinately rescue energy and mass in sarcopenia.

physiology↗