Biology subjects

Abdellatif, M.

Publications and source records attributed to Abdellatif, M..

8 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↗

bioRxiv2024

Phosphorylation of CRYAB Induces a Condensatopathy to Worsen Post-Myocardial Infarction Left Ventricular Remodeling.

Protein aggregates are emerging therapeutic targets in rare monogenic causes of cardiomyopathy and amyloid heart disease, but their role in more prevalent heart failure syndromes remains mechanistically unexamined. We observed mis-localization of desmin and sarcomeric proteins to aggregates in human myocardium with ischemic cardiomyopathy and in mouse hearts with post-myocardial infarction ventricular remodeling, mimicking findings of autosomal-dominant cardiomyopathy induced by R120G mutation in the cognate chaperone protein, CRYAB. In both syndromes, we demonstrate increased partitioning of CRYAB phosphorylated on serine-59 to NP40-insoluble aggregate-rich biochemical fraction. While CRYAB undergoes phase separation to form condensates, the phospho-mimetic mutation of serine-59 to aspartate (S59D) in CRYAB mimics R120G-CRYAB mutants with reduced condensate fluidity, formation of protein aggregates and increased cell death. Conversely, changing serine to alanine (phosphorylation-deficient mutation) at position 59 (S59A) restored condensate fluidity, and reduced both R120G-CRYAB aggregates and cell death. In mice, S59D CRYAB knock-in was sufficient to induce desmin mis-localization and myocardial protein aggregates, while S59A CRYAB knock-in rescued left ventricular systolic dysfunction post-myocardial infarction and preserved desmin localization with reduced myocardial protein aggregates. 25-Hydroxycholesterol attenuated CRYAB serine-59 phosphorylation and rescued post-myocardial infarction adverse remodeling. Thus, targeting CRYAB phosphorylation-induced condensatopathy is an attractive strategy to counter ischemic cardiomyopathy.

cell biology↗

bioRxiv2020

Conserved cysteines in titin sustain the mechanical function of cardiomyocytes

The protein titin determines cardiomyocyte contraction and truncating variants in the titin gene (TTN) are the most common cause of dilated cardiomyopathy (DCM). Different to truncations, missense variants in TTN are currently classified as variants of uncertain significance due to their high frequency in the population and the absence of functional annotation. Here, we report the regulatory role of conserved, mechanically active titin cysteines, which, contrary to current views, we uncover to be reversibly oxidized in basal conditions leading to isoform- and force-dependent modulation of titin stiffness and dynamics. Building on our functional studies, we demonstrate that missense mutations targeting a conserved titin cysteine alter myocyte contractile function and cause DCM in humans. Our findings have a direct impact on genetic counselling in clinical practice. One sentence summaryMutations targeting cysteines key to the mechanoredox control of titin cause human dilated cardiomyopathy

physiology↗

bioRxiv2019

Large scale differential gene expression analysis identifies genes associated with Bipolar Disorder

Background and purposeBipolar disorder (BD) is a common psychiatric disorder with high morbidity and mortality. Several polymorphisms have been found to be implicated in the pathogenesis of BD, however, these loci have small effect sizes that fail to explain the high heritability of the disease. Here, we provide more insights into the genetic basis of BD by identifying the differentially expressed genes (DEGs) and their associated pathways and biological processes in post-mortem brain tissues of patients with BD.\n\nMethodsEight datasets were eligible for the differential expression analysis. We used six datasets for the discovery of the gene signature and used the other two for independent validation. We performed the multi-cohort analysis by a random-effect model using R and MetaIntegrator package.\n\nResultsThe initial analysis resulted in the identification of 126 DEGs (30 up-regulated and 94 down-regulated). We refined this initial signature by a forward search process and resulted in the identification of 22 DEGs (6 up-regulated and 16 down-regulated). We validated the final gene signature in the independent datasets and resulted in an Area Under the ROC Curve (AUC) of 0.756 and 0.76, respectively. We performed gene set enrichment analysis (GSEA) which identified several biological processes and pathways related to BD including Ca transport, inflammation and DNA damage response.\n\nConclusionOur findings support the previous findings that link BD pathogenesis to abnormalities in glial inflammation and calcium transport and also identify several other biological processes not previously reported to be associated with the development of the disease. Such findings will improve our understanding of the genetic basis underlying BD and may have future clinical implications.

bioinformatics↗

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↗

bioRxiv2018

PathoPhenoDB: linking human pathogens to their disease phenotypes in support of infectious disease research

Understanding the relationship between the pathophysiology of infectious disease, the biology of the causative agent and the development of therapeutic and diagnostic approaches is dependent on the synthesis of a wide range of types of information. Provision of a comprehensive and integrated disease phenotype knowledgebase has the potential to provide novel and orthogonal sources of information for the understanding of infectious agent pathogenesis, and support for research on disease mechanisms. We have developed PathoPhenoDB, a database containing pathogen-to-phenotype associations. PathoPhenoDB relies on manual curation of pathogen-disease relations, on ontology-based text mining as well as manual curation to associate phenotypes with infectious disease. Using Semantic Web technologies, PathoPhenoDB also links to knowledge about drug resistance mechanisms and drugs used in the treatment of infectious diseases. PathoPhenoDB is accessible at http://patho.phenomebrowser.net/, and the data is freely available through a public SPARQL endpoint.

bioinformatics↗