bioRxiv Science⌕ Search

bioRxiv · 10.1101/2024.01.17.575991

Human induced pluripotent stem cell-derived cardiomyocytes to study inflammation-induced diastolic dysfunction

Abstract

Heart failure with preserved ejection fraction (HFpEF) is commonly found in persons living with HIV (PLWH) even when antiretroviral therapy (ART) suppresses HIV viremia. However, studying this condition has been challenging because an appropriate animal model is not available. In this paper, we studied calcium transient in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) in culture to simulate the cardiomyocyte relaxation defect noted in of PLWH and HFpEF and to assess whether various drugs have an effect. We show that treatment of hiPSC-CMs with inflammatory cytokines (such as interferon-{gamma} or TNF-) impair their Ca2+ uptake into sarcoplasmic reticulum and that SGLT2 inhibitors, clinically proven as effective for HFpEF, reverse this effect. Additionally, treatment with mitochondrial antioxidants (like mito-Tempo) and certain antiretrovirals resulted in the reversal of the effects of these cytokines on calcium transient. Finally, incubation of hiPSC-CMs with serum from HIV patients with and without diastolic dysfunction did not alter their Ca2+-decay time, indicating that the exposure to the serum of these patients is not sufficient to induce the decrease in Ca2+ uptake in vitro. Together, our results indicate that hiPSC-CMs can be used as a model to study molecular mechanisms of inflammation-mediated abnormal cardiomyocyte relaxation and screen for potential new interventions.

Source connections

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Ardehali, H., Tatekoshi, Y., Chen, C., Shapiro, J. S., Chang, H.-C., Blancard, M., Burridge, P. W., Feinstein, M., D'Aquila, R., Hsue, P.. 2024-01-20. Human induced pluripotent stem cell-derived cardiomyocytes to study inflammation-induced diastolic dysfunction. https://doi.org/10.1101/2024.01.17.575991

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

A G-Quadruplex Containing First Intron Harbors a Functional Polyadenylation Signal in TP53

First introns of mammalian genes are often longer than other introns and may contain regulatory elements, suggesting that they may have roles in gene regulation. We detected a previously unannotated, low abundance intronic transcript, TP53-INT1, using long-read direct RNA sequencing data. TP53-INT1 has low coding potential and terminates within the first and longest intron of TP53. The transcript structure and 3'-end were validated by independent experimental and in silico evidence. We identified a canonical polyadenylation signal upstream of the transcript termination site and demonstrated its functionality using reporter assays. Furthermore, a potential G-quadruplex (G4)-forming sequence was identified upstream of this polyadenylation signal. The G4-forming potential was confirmed using spectroscopic and thermal stability analyses. Complementing the in vitro characterizations, treatment with Pyridostatin, a G4-stabilizing drug, was associated with decreased TP53 expression. Together, these findings characterize a previously unannotated TP53 intronic transcript and reveal a local genomic context combining accessible chromatin, a functional polyadenylation signal, and a potential G4-forming sequence that may influence full-length transcription.

molecular biology↗

LOca-1: A minimal calcium-activated arginyl-specific orthocaspase from the Loki's Castle hydrothermal vent field

Orthocaspases are prokaryotic homologs of metacaspases within the C14 family of cysteine proteases, yet their biochemical properties and cellular roles remain poorly understood. Here, we report the discovery and comprehensive characterization of LOca-1, a metagenome-derived orthocaspase from the Loki's Castle hydrothermal vent field. LOca-1 consists primarily of a single, conserved p20 catalytic domain and undergoes calcium-dependent activation through cleavage at a conserved arginine residue. Once activated, LOca-1 displays strict arginyl-specific proteolytic activity and strong selectivity for residues surrounding the cleavage site. The enzyme is both thermoactive and thermostable, exhibiting maximal activity at 65 {degrees}C and a melting temperature of approximately 72 {degrees}C. Structural modelling revealed conservation of the catalytic core relative to plant metacaspases despite substantial sequence divergence. To our knowledge, LOca-1 is only the second biochemically characterized orthocaspase and the first reported from a deep-sea hydrothermal vent environment. LOca-1 expands the known biochemical diversity of prokaryotic metacaspase homologs and provides insights into the properties of a minimal p20-domain orthocaspase. Together, our findings establish LOca-1 as a thermostable, calcium-activated arginyl-specific orthocaspase and provide a foundation for future studies of orthocaspase function in prokaryotes.

molecular biology↗

A TMEM175 Mutation Disrupts the Lysosomal-Mitochondrial Axis Causing Short QT Syndrome and Sudden Cardiac Death

Short QT Syndrome (SQTS) is a rare cardiac channelopathy characterized by abnormally short QTc intervals and increased sudden cardiac death (SCD) risk. Only 20-30% of SQTS cases have been linked to genetic mutations, typi-cally in surface membrane ion channels. We identified a novel lysosomal TMEM175 gene mutation (p.Arg377His) in 7 patients in a family with SQTS and SCD. Genetic analyses, including whole exome sequencing in the family and rare-variant burden testing in [~]118,000 UK Biobank participants, sug-gested an association between TMEM175 rare variants and QT interval short-ening. Functional studies in CRISPR-engineered mice and patient-specific induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) revealed that TMEM175R377H causes shortened QT intervals and hastened repolariza-tion, respectively, as well an increased arrhythmia susceptibility. Isolated TMEM175R377H cardiomyocytes showed action potential duration (APD) abbre-viation, confirmed in whole TMEM175R377H mouse hearts and patient-specific iPSC-CM monolayers. In silico and electron microscopy studies showed that TMEM175R377H disrupts lysosomal-mitochondrial interactions, leading to mito-chondrial dysfunction, as evidenced by the reduced maximal respiration and spare respiratory capacity, with reduced ATP production, IKATP activation, and APD shortening. This mutation represents the first non-sarcolemmal ion chan-nel defect associated with SQTS and high SCD risk, potentially expanding the genetic landscape of the disease.

molecular biology↗