Biology subjects

Lettlova, S.

Publications and source records attributed to Lettlova, S..

4 recordsLinked to original sources

bioRxiv2024

AQP1 Differentially Orchestrates Endothelial Cell Senescence

Accumulation of senescent endothelial cells (ECs) with age is a pivotal driver of cardiovascular diseases in aging. However, little is known about the mechanisms and signaling pathways that regulate EC senescence. In this report, we delineate a previously unrecognized role of aquaporin 1 (AQP1) in orchestrating extracellular hydrogen peroxide (H2O2)-induced cellular senescence in aortic ECs. Our findings underscore AQP1s differential impact on senescence hallmarks, including cell-cycle arrest, senescence-associated secretory phenotype (SASP), and DNA damage responses, intricately regulating angiogenesis. In proliferating ECs, AQP1 is crucial for maintaining angiogenic capacity, whereas disruption of AQP1 induces morphological and mitochondrial alterations, culminating in senescence and impaired angiogenesis. Conversely, Aqp1 knockdown or selective blockade of AQP1 in senescent ECs rescues the excess H2O2-induced cellular senescence phenotype and metabolic dysfunction, thereby ameliorating intrinsic angiogenic incompetence. Mechanistically, AQP1 facilitates H2O2 transmembrane transport, exacerbating oxidant-sensitive kinases CaMKII-AMPK. This process suppresses HDAC4 translocation, consequently de-repressing Mef2A-eNOS signaling in proliferating ECs. However, in senescent ECs, AQP1 overexpression is linked to preserved HDAC4-Mef2A complex and downregulation of eNOS signaling. Together, our studies identify AQP1 as a novel epigenetic regulator of HDAC4-Mef2A-dependent EC senescence and angiogenic potential, highlighting its potential as a therapeutic target for antagonizing age-related cardiovascular diseases. Highlights* AQP1 is upregulated in aortic endothelial cells with aging * AQP1 differentially orchestrates H2O2-mediated EC senescence * AQP1 plays a dual role in regulating angiogenesis in proliferating and senescent ECs * AQP1 controls EC function by differentially modulating HDAC4-Mef2A pathway * AQP1 deficiency restores angiogenic capacity in senescent ECs

molecular biology↗

bioRxiv2020

Msp1/ATAD1 restores mitochondrial function in Zellweger Spectrum Disease

Peroxisomal Biogenesis Disorders (PBDs) are a class of inherited metabolic disorders with profound neurological and other phenotypes. The most severe PBDs are caused by mutations in peroxin genes, which result in nonfunctional peroxisomes typically through impaired protein import. In order to better understand the molecular causes of Zellweger Spectrum Disease (ZSD) -the most severe PBDs -, we investigated the fate of peroxisomal mRNAs and proteins in ZSD model systems. We found that loss of peroxisomal import has no effect on peroxin mRNA expression or translational efficiency. Instead, peroxin proteins--still produced at high levels-- aberrantly accumulate on the mitochondrial membrane, impairing respiration and ATP generation. Finally, we rescued mitochondrial function in fibroblasts derived from human patients with ZSD by overexpressing ATAD1, an AAA-ATPase that functions in mitochondrial quality control. These findings might provide a new focus of PBD therapies in supporting quality control pathways that protect mitochondrial function.

cell biology↗

bioRxiv2020

Mitochondrial fatty acid synthesis coordinates mitochondrial oxidative metabolism

Cells harbor two systems for fatty acid synthesis, one in the cytoplasm (catalyzed by fatty acid synthase, FASN) and one in the mitochondria (mtFAS). In contrast to FASN, mtFAS is poorly characterized, especially in higher eukaryotes, with the major product(s), metabolic roles, and cellular function(s) being essentially unknown. Here we show that hypomorphic mtFAS mutants display a severe loss of electron transport chain (ETC) complexes and exhibit compensatory metabolic activities including reductive carboxylation. This effect on ETC complexes appears to be independent of protein lipoylation, the best characterized function of mtFAS, as mutants lacking lipoylation have an intact ETC. Finally, mtFAS impairment blocks the differentiation of skeletal myoblasts in vitro. Together, these data suggest that ETC activity in mammals is profoundly controlled by mtFAS function, thereby connecting anabolic fatty acid synthesis with the oxidation of carbon fuels.

biochemistry↗

bioRxiv2019

Preparation of single-cell suspension from mouse breast cancer focusing on preservation of original cell state information and cell type composition

Single-cell analysis of gene expression has become a very popular method during the last decade. Unfortunately, appropriate standardization and workflow optimization remain elusive. The first step of the single cell analysis requires that the solid tissue be disassociated into a suspension of individual cells. However, during this step several technical bias can arise which can later result in the misinterpretation of the data. The goal of this study was to identify and quantify the effect of these technical factors on the quality of the single-cell suspension and the subsequent interpretation of the produced expression data. We tested the effects of various enzymes used for dissociation, several centrifugation forces, dissociation temperatures and the addition of Actinomycin D, a gene expression inhibitor. RT-qPCR was used to assess the effect from each parameter alteration, while a single-cell RNA sequencing experiment was used to confirm the optimized factors. Our concluding results provide a complete protocol for the tissue dissociation of mouse mammary tumour from 4T1 cells that preserves the original cell state and is suitable for any single-cell RNA sequencing analysis. Furthermore, our workflow may serve as a guide for the optimization of the dissociation procedure of any other tissue of interest, which would ultimately improve the reproducibility of the reported data.

cancer biology↗