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Biology subjects

Vasam, G.

Publications and source records attributed to Vasam, G..

3 recordsLinked to original sources

Treatment with a selective histone deacetylase (HDAC) 1 and 2 inhibitor in aged mice rejuvenates multiple organ systems

The process of aging increases the risk of developing age-related diseases, which come at great societal healthcare costs and suffering to individuals. Meanwhile, targeting the basic mechanisms of aging can reduce the risk of developing age-related diseases during aging, essentially resulting in a healthy aging process. Multiple aging pathways exist, which over past decades have systematically been confirmed through gene knockout or overexpression studies in mammals and the ability to increase healthy lifespan. In this work, we perform transcriptome-based drug screening to identify small molecules that mimic the transcriptional profiles of long-lived genetic interventions in mammals. We identify one small molecule whose transcriptional effects mimic diverse known genetic longevity interventions: compound 60 (Cmpd60), which is a selective inhibitor of histone deacetylase 1 (HDAC1) and 2 (HDAC2). In line with this, in a battery of molecular, phenotypic, and bioinformatic analyses, in multiple disease cell and animal models, we find that Cmpd60 treatment rejuvenates multiple organ systems. These included the kidney, brain, and heart. In renal aging, Cmpd60 reduced partial epithelial-mesenchymal transition (EMT) in vitro and decreased fibrosis in vivo. For the aging brain, Cmpd60 reduced dementia-related gene expression in vivo, effects that were recapitulated when treating the APPSWE-1349 Alzheimer mouse. In cardiac aging, Cmpd60 treatment activated favorable developmental gene expression in vivo and in line with this, improved ventricular cardiomyocyte contraction and relaxation in a cell model of cardiac hypertrophy. Our work establishes that a systemic, two-week treatment with an HDAC1/2 inhibitor serves as a multi-tissue, healthy aging intervention in mammals. This holds potential for translation towards therapeutics that promote healthy aging in humans.

pathology↗

Reducing mitochondrial ribosomal gene expression does not alter metabolic health or lifespan in mice

Maintaining mitochondrial function is critical to an improved health span and lifespan. Introducing mild stress by inhibiting mitochondrial translation invokes the mitochondrial unfolded protein response (UPRmt) and increases lifespan in several animal models. Notably, lower mitochondrial ribosomal protein (MRP) expression also correlates with increased lifespan in a reference population of mice. In this study, we tested whether partially reducing the expression of a critical MRP, Mrpl54, reduced mitochondrial DNA-encoded protein content, induced the UPRmt, and affected lifespan or metabolic health using germline heterozygous Mrpl54 mice. Despite reduced Mrpl54 expression in multiple organs and a reduction in mitochondrial-encoded protein expression in myoblasts, we identified few significant differences between male or female Mrpl54+/- and wild type mice in initial body composition, respiratory parameters, energy intake and expenditure, or ambulatory motion. We also observed no differences in glucose or insulin tolerance, treadmill endurance, cold tolerance, heart rate, or blood pressure. There were no differences in median life expectancy or maximum lifespan. Overall, we demonstrate that genetic manipulation of Mrpl54 expression reduces mitochondrial-encoded protein content but is not sufficient to improve healthspan in otherwise healthy and unstressed mice.

cell biology↗

GCN5 Maintains Muscle Integrity by Acetylating YY1 to Promote Dystrophin Expression

This work identifies a novel role for the acetyltransferase GCN5 in regulating muscle integrity through inhibition of DNA binding activity of the transcriptional repressor YY1. Here we report that in mice a muscle-specific knockout of GCN5 (Gcn5skm-/-) reduces the expression of key structural muscle proteins, including dystrophin, resulting in myopathy. Supporting our observation, a meta-analysis between the differential transcriptome of Gcn5skm-/- muscle and all available open-access data sets identified top correlations with musculoskeletal diseases in humans. GCN5 was found to acetylate YY1 at two residues (K392 and K393), which disrupts the interaction between the YY1 zinc-finger region and DNA. De/acetylation mimics for these YY1 post-translational modifications modulated muscle structural gene expression and DNA binding. Analysis of human GTEx data also found positive and negative correlations between fiber diameter and GCN5 and YY1 respectively. Collectively, our results demonstrate that GCN5 acetyltransferase activity regulates YY1 DNA binding and expression of dystrophin to modulate muscle integrity.

cell biology↗