Biology subjects

Hemanna, S.

Publications and source records attributed to Hemanna, S..

4 recordsLinked to original sources

bioRxiv2026

Loss of cardiomyocyte eukaryotic elongation factor 1 A2 in adult mice triggers cardiomyopathy due to defective proteostasis

Eukaryotic elongation factor 1A (eEF1A) delivers aminoacyl-tRNAs to ribosomes but also has additional, non-canonical functions. Mammals express two paralogs: eEF1A1 is ubiquitous, whereas eEF1A2 is confined to adult cardiomyocytes, skeletal myocytes, and neurons. Mutations in EEF1A2 cause cardiomyopathy, but underlying mechanisms remain unclear. Using adult, cardiomyocyte-specific Eef1a2 knock-out (Eef1a2-cKO) and Eef1a1/Eef1a2 double knock-out mice, we show that Eef1a2-cKO animals develop cardiomyopathy with increased mortality, systolic dysfunction, and fibrosis, despite unchanged global protein synthesis, while double knock-out mice die early in a sudden manner. Multi-omics analyses reveal post-transcriptional upregulation of ribosomal proteins and translational regulators in both models. Eef1a2-cKO hearts accumulate autophagosomes and protein aggregates, indicating defective autophagy. Mechanistically, we found that eEF1A2 functions as a chaperone supporting protein folding and proteostasis in cardiomyocytes. Early Rapamycin treatment (mTORC1 inhibition) normalizes systolic heart function and survival in Eef1a2-cKO mice and clears autophagosomes and protein aggregates. Thus, eEF1A2 maintains cardiac proteostasis, and mTORC1 inhibition may represent a therapeutic strategy for patients with EEF1A2 mutations.

physiology↗

bioRxiv2025

Comprehensive immune profiling of melanoma-draining lymph nodes identifies plasmacytoid dendritic cells as new biomarker for PD-L1 blockade

Immune checkpoint blockade (ICB) has become a powerful weapon in the treatment of melanoma and other cancer types. Still, only a minority of patients profits from this type of therapy. As ICB is associated with considerable adverse effects, predictive biomarkers to select patients for ICB treatment are urgently needed. Here, we comprehensively immunophenotyped primary tumors and tumor-draining lymph nodes (tdLNs) from a panel of ICB-resistant and -sensitive melanoma models in mice. Surprisingly, we found that whereas tumor-infiltrating CD8+ T cells showed strong responses to PD-L1 blockade in ICB-sensitive melanoma, CD8+ T cell profiles in tdLNs were very similar in ICB responder and non-responder models. In contrast, we identified distinct myeloid immune profiles in tdLNs correlating with ICB responsiveness, including a low frequency of activated dendritic cells and a high frequency of plasmacytoid dendritic cells (pDCs). Notably, pDC marker genes and frequencies in tdLNs of melanoma patients correlated with favorable outcome. Thus, the level of pDCs in tdLNs represents a potential new biomarker for ICB in melanoma patients.

immunology↗

bioRxiv2025

A deep, quantitative lipid atlas of extracellular vesicles across multiple cell lines

Extracellular vesicles (EVs) are subcellular particles surrounded by a lipid bilayer membrane and incorporating various additional biomolecules derived from their donor cell. In many disease contexts circulating EVs have received increasing scientific attention due to their potential diagnostic and prognostic value. Additionally, EVs have been ascribed multiple biological functions, ranging from cellular waste disposal to sophisticated, intercellular communication. Consequently, EVs involved in pathological processes may represent therapeutic targets, whereas EV-based therapeutics are being developed for targeted delivery of molecular cargoes in vivo. Detailed knowledge of the molecular content of natural EVs derived from diverse cellular origins is crucial to identify biomarkers, dissect EV functions, and optimize EV engineering for therapeutic purposes. Although the lipid composition of biological membranes has a significant impact on their biophysical and -chemical properties and may affect signaling and interactions at the molecular and cellular level, relatively little is known about the lipid composition of EV membranes. Here, we applied high resolution mass spectrometry to deeply and quantitatively characterize the lipidome of EVs isolated from a panel of malignant and non-malignant cell lines, providing a comprehensive data resource for biomarker research and EV engineering efforts. Furthermore, subset comparisons indicate striking differences between lipid profiles of EVs isolated from cells of different tissue origin, suggesting distinct membrane characteristics that could affect EV biodistribution and function in vivo.

cell biology↗

bioRxiv2022

Secreted long non-coding RNAs Gadlor1 and Gadlor2 affect multiple cardiac cell types and aggravate cardiac remodeling during pressure overload

BackgroundPathological overload triggers maladaptive myocardial remodeling that leads to heart failure. Recent studies have shown that long non-coding RNAs (lncRNAs) regulate cardiac remodeling. This study investigates two recently discovered, secreted lncRNAs, Gadlor1 and Gadlor2 (Gadlor 1/2). MethodsWe generated compound Gadlor1/2 knock-out (KO) mice and compared their response to pressure overload by transverse aortic constriction (TAC) to that of wild-type (WT) littermates. Endothelial cells, fibroblasts and cardiomyocytes were isolated from the hearts of both genotypes after TAC and their transcriptome was investigated by RNA sequencing. Gadlor target proteins were identified by RNA antisense purification coupled with mass spectrometry (RAP-MS) in cardiomyocytes. In addition, we investigated the effects of cardiac overexpression of Gadlor1/2. ResultsGadlor1/2 are jointly upregulated in failing mouse hearts as well as in the myocardium of heart failure patients. Cardiac overexpression of Gadlor1 and Gadlor2 aggravated myocardial dysfunction and enhanced hypertrophic and fibrotic remodeling in mice exposed to pressure overload. Compound Gadlor1/2 KO mice, in turn, exerted markedly reduced myocardial hypertrophy, fibrosis and dysfunction, but more angiogenesis during short and long-standing pressure overload. Paradoxically, Gadlor1/2 KO mice suffered from sudden death during prolonged overload, possibly due to cardiac arrhythmia. Gadlor1 and Gadlor2, which are mainly expressed in endothelial cells (ECs) in the heart, where they inhibit pro-angiogenic gene-expression, are strongly secreted within extracellular vesicles (EVs). These EVs transfer Gadlor lncRNAs to cardiomyocytes, where they bind and activate calmodulin-dependent kinase II, induce pro-hypertrophic gene-expression and enhance calcium re-uptake into the sarcoplasmic reticulum. ConclusionGadlor1 and Gadlor2 are lncRNAs that are mainly enriched in EC-derived EVs and are jointly upregulated in mouse and human hearts during pathological overload. We reveal a crucial endothelial cell-cardiomyocyte crosstalk, which aims at restoring calcium homeostasis in cardiomyocytes during overload at the cost of aggravated hypertrophy and fibrosis.

systems biology↗