Biology subjects

Sayed, D.

Publications and source records attributed to Sayed, D..

6 recordsLinked to original sources

bioRxiv2026

Restoring Klf9 Expression with Pressure Overload Leads to Metabolic Maladaptation and Early Onset of Heart Failure

Klf9 is a cardiac-enriched transcription factor of the Kruppel-like factor (Klf) family. Klf9 levels decrease during cardiac hypertrophy; however, no studies have examined its transcriptional targets or role in the progression of hypertrophy. Here, we report genome-wide differential Klf9 occupancy during cardiac hypertrophy, with a predominant enrichment at the metabolic gene promoters. Further, using conditional Klf9 knock-in mice subjected to pressure overload for 1 or 2 weeks, we show that restoring Klf9 expression initially inhibits hypertrophy but later leads to early-onset heart failure. We conclude that a decrease in Klf9 is required for metabolic adaptations that support the development of compensatory hypertrophy.

cell biology↗

bioRxiv2026

Restricting Dietary Isoleucine Promotes Foxo3-Dependent Mitochondrial Respiration by Reducing Caloric Intake

Our prior work demonstrated that lowering dietary branched-chain amino acids (BCAAs) improves cardiac outcomes during pressure overload-induced stress. Here, we identify isoleucine restriction (IleR) as the key driver of this effect. Dietary isoleucine restriction induces hypophagia and weight loss, recapitulating the effects of caloric restriction (CR). Although it does not prevent the initial development of left ventricular hypertrophy, it halts its progression and the decline in ejection fraction compared with controls. This is associated with preservation of electron transport chain (ETC) gene expression, cristae structure, NAD+/NADH levels, and mitochondrial respiratory capacity in cardiomyocytes, which is recapitulated by CR. Mechanistically, both IleR and CR diets increase Foxo3 expression, thereby blocking the decline in expression of its target ETC and mitochondrial genome-encoded genes. Consequently, this improves mitochondrial respiratory capacity and reduces cardiac fibrosis. We conclude that restricting dietary isoleucine improves cardiac health by increasing Foxo3 expression and mitochondrial function via a cell-autonomous mechanism and by reducing caloric intake.

molecular biology↗

bioRxiv2025

Constitutive expression of cardiomyocyte Klf9 precipitates metabolic dysfunction and spontaneous heart failure.

Metabolic adaptations and flexibility during development and disease play an essential in cardiomyocyte function and survival. We recently reported Glucocorticoid receptor (GR)-Kruppel-like factor 9 (Klf9) axis in mediating metabolic adaptations in cardiomyocytes stimulated with Dexamethasone. Klf9 expression decreases in hypertrophic and failing hearts, suggesting its importance in cardiac homeostasis and its potential contribution to dysfunction under pressure overload. Genome wide Klf9 occupancy in adult hearts revealed 2,242 genes directly associated with Klf9, with enrichment in metabolic pathways, autophagy, ubiquitin-mediated proteolysis, and cellular senescence. We generated and characterized a conditional cardiac specific Klf9 knock-In (Klf9KI) mice, which developed progressive cardiac hypertrophy, cardiac dysfunction and cardiac failure by 8wks of age, with mortality by 12-14wks. RNA-seq analysis at 1wk, 4wks, and 8wks showed stage-specific transcriptional changes. At 1 week, 64.81% of differentially expressed genes were downregulated, aligning with Klf9s predicted role as a transcriptional repressor. At 4wks and 8wks, more genes were upregulated, suggesting more of secondary targets in response to cardiac phenotype. KEGG pathway analysis showed dysregulation in lipid, carbohydrate and glutathione metabolism, transcriptional regulation, apoptosis, and innate immunity. Untargeted Metabolomics at 4wks identified significant alterations in tissue metabolite levels, particularly in pathways involving fatty acid metabolism, amino acids, and glucose, correlating with transcriptome data. Mitochondrial function assays revealed progressive dysregulation. At 2 weeks, complex I activity was significantly reduced, while complex II and IV activities were partially preserved. By 4 weeks, all measured respiratory complexes showed significant declines, consistent with decline in mitochondrial function. These mitochondrial deficits preceded overt cardiac dysfunction and likely contributed to the development of hypertrophy and failure. In conclusion, constitutive Klf9 overexpression disrupts transcriptional and metabolic homeostasis, driving progressive hypertrophy, cardiac dysfunction, and failure.

cell biology↗

bioRxiv2023

Klf9 plays a critical role in GR dependent metabolic adaptations in cardiomyocytes

Glucocorticoids (GCs) through activation of the Glucocorticoid receptor (GR) play an essential role in cellular homeostasis during physiological variations and in response to stress. GC-GR signaling has been involved in regulating several cellular processes including metabolism, circadian rhythm and inflammation for diurnal adaptations. Our genomic GR binding (ChIP) and transcriptome (RNAseq) data from Dexamethasone (Dex) treatment in cardiomyocytes show an early (1hr) differential regulation of mostly transcription factors, followed by sequential change in downstream signaling pathways (6-24hr). Here, we examine the role of an early direct target of GR, Kruppel-like factor 9 (Klf9) in cardiomyocyte metabolic homeostasis. Our Klf9-ChIPseq identified 2150 genes with increase in promoter Klf9 binding in response to Dex. Functional annotation of these genes lists metabolic pathway on the top of KEGG pathway, along with genes regulating transcription and survival. Further, our transcriptome analysis of Dex treated cardiomyocytes with or without knockdown of Klf9 reveal differential regulation of 1777 genes, of which a reversal in expression is seen in 1640 ([~]92%) genes with knockdown of Klf9 compared to Dex. Conversely, only 137 ([~]8%) genes show further dysregulation in expression with siKLf9 as Dex treated cardiomyocytes. Gene ontology of these 1640 genes show metabolic genes on the top, including genes involved in glycolysis and oxidative phosphorylation. Expectedly, knockdown of Klf9 in cardiomyocytes inhibits Dex induced increase in glycolysis and spare respiratory capacity, as measured by glycolysis and mito stress tests, respectively. Thus, we conclude that cyclic, diurnal GC mediated GR activation, through Klf9 -dependent feedforward signaling plays a central role in maintaining cellular homeostasis through metabolic adaptations in quiescent and stressed cardiomyocytes.

cell biology↗

bioRxiv2022

T cell subsets in chronic hepatitis C patients genotype 4 who achieved SVR following DAAs Therapy

BackgroundT cells are the primary effector cells that mediate viral clearance in spontaneous recovery from HCV infection and T cell dysfunction is a hallmark of progression to chronic HCV infection. Material and methodsThis study included 49 well charcterised HCV genotype 4-infected patients at Egyptian Liver Research Institute and Hospital (ELRIAH), Mansoura, Egypt, who were enrolled to receive direct acting antiviral therapy for hepatitis C. Immuno-phenotyping was performed to assess the expression of multiple T cell lineage, activation and inhibitory receptors. This was done before treatment, during treatment, at end of treatment and one year after treatment. 50 patients were also enrolled as control. ResultsOur data showed, significant increase in the percentages of CD8+ cells as compared to control group. The percentages of PD-1 expression on the CD8+ T-cell population were signifecntly elevated in patients before treatment (p<0.001). Significant increase in Treg (CD4+CD25hFoxP3+) subsets was noticed in comparison with control pateints. The expression of the inhibitory and activated markers in CD8+ T-cells was markedly reduced but more obvios in exhausted cytotoxic T cells compared to baseline finding (p<0.001). exhausted (PD1+CD8+) T-cells from HCV+ individuals reduced markedly after 4 weeks of DAA therapy (by 3 folds, p <0.001). Intereatingly it started to increase gradually again at the end of treatment and after 1 year but the increase doesnt reach levels noticed in healthy control subjects. ConclusionUnderstanding the mechanisms of immune dysfunction and barriers to immune restoration after HCV cure will aid in better understanding of the remaining negative long-term health outcomes for HCV patients and the possibility of HCC development.

immunology↗

bioRxiv2019

H2A.Z-dependent and -independent recruitment of metabolic enzymes to chromatin required for histone modifications

H2A.Z plays a fundamental role in the regulation of transcription and epigenetics, however, the mechanisms that underlie its functions are not fully understood. Using rapid chromatin immunoprecipitation-mass spectrometry, we uncovered the association of H2A.Z-bound chromatin with an array of tricarboxylic acid cycle and beta-oxidation enzymes in the mouse heart. Recombinant green florescence fusion proteins combined with mutations of putative nuclear localization signals of select enzymes, including acetyl-CoA acyltransferase 2 (ACAA2), oxoglutarate dehydrogenase (OGDH), and isocitrate dehydrogenase 2 confirmed their nuclear localization and chromatin binding in both rodent and human cells. Conclusively, chromatin immunoprecipitation-deep sequencing, confirmed the selective association of ACAA2 and OGDH with H2A.Z-occupied transcription start sites. Finally, human H2A.Z-deficient HAP1 cells exhibited reduced chromatin-bound metabolic enzymes, with the exception of pyruvate dehydrogenase, accompanied with reduced posttranslational histone modifications. Thus, the data show that metabolic enzymes are recruited to active promoters for potential site-directed epigenetic modifications.

molecular biology↗