Cardiovascular System Commons^™

Stim1-Dependent Treg Dysfunction Promotes Cardiometabolic Hfpef: Insights From Patients And Animal Studies, Balaji Srinivas, Alluri Kiran, Hongmei Peng, Jiang Xu, Paula Fortuno, Jennifer May, Ismail El Moudden, Nour-Eddine Rhaleb, John M. Herre, Raymond L. Benza, Khalid Matrougui

Department of Biomedical and Translational Sciences Faculty Publications

Background

Heart failure with preserved ejection fraction (HFpEF) arises from chronic cardiometabolic and vascular stress and is increasingly recognized as an inflammatory syndrome with immune dysregulation. Regulatory T cells (Tregs) are critical modulators of cardiovascular inflammation, yet the mechanisms driving Treg dysfunction in HFpEF remain poorly defined. stromal interaction molecule 1 (STIM1)-dependent calcium signaling is a key stress-responsive pathway in immune cells; however, its role in Treg maladaptation during HFpEF remains unknown.

Methods

Circulating Tregs from patients with and without HFpEF were analyzed for abundance, STIM1 expression, and stress-associated signaling pathways. To establish causality, mice with Treg-specific deletion of STIM1 …

The Central Role For Troponin C Amino-Terminal ⍺-Helix In Vertebrate Thin Filiment Ca²⁺-Activation, Yun Shi, Lauren A. Blackwell, Ryan K. Schroy, B. Max Cleland, Cristina M. Risi, Michelle S. Parvatiyar, Jose R. Pinto, Vitold E. Galkin, P. Bryant Chase

Department of Biomedical and Translational Sciences Faculty Publications

Troponin C (TnC) is the Ca²⁺-sensing subunit of troponin that is responsible for activating thin filaments in striated muscle, and, in turn, for regulating the systolic and diastolic contractile function of cardiac muscle. The secondary structure of vertebrate TnC is mainly composed of α-helices, with nine helices named sequentially, starting from the amino terminus, from N to A–H. The N-helix is a 12-residue-long α-helix located at the extreme amino terminus of the protein and is the only helical structure that does not participate in forming Ca²⁺-binding EF-hands. Evolutionarily, the N-helix is found only in TnC from mammalian species and most …

Interaction Of Cardiac Leiomodin With The Native Cardiac Thin Filament, Madison Little, Cristina M. Risi, Tania M. Larrinaga, Mason D. Summers, Tyler Nguyen, Garry E. Smith Jr., Jennifer Atherton, Carol C. Gregorio, Alla S. Kostyukova, Vitold E. Galkin

Department of Biomedical and Translational Sciences Faculty Publications

Every heartbeat depends on cyclical contraction-relaxation produced by the interactions between myosin-containing thick and actin-based thin filaments (TFs) arranged into a crystalline-like lattice in the cardiac sarcomere. Therefore, the maintenance of thin filament length is crucial for myocardium function. The thin filament is comprised of an actin backbone, the regulatory troponin complex and tropomyosin that controls interactions between thick and thin filaments. Thin filament length is controlled by the tropomodulin family of proteins; tropomodulin caps pointed ends of thin filaments, and leiomodin (Lmod) promotes elongation of thin filaments by a “leaky-cap” mechanism. The broader distribution of Lmod on the thin …

Deletion Of Chop In Beta Cell Protects Mice From Cardiovascular Complications In Type 2 Diabetes: Evidence From A Pre-Clinical Mouse Model, Balaji Srinivas, Kiran Alluri, Nour-Eddine Rhaleb, Khalid Matrougui

Department of Biomedical and Translational Sciences Faculty Publications

Introduction

Cardiovascular complications are the leading cause of morbidity and mortality in patients with type 2 diabetes (T2D), which is recognized as a major independent risk factor for coronary artery disease, stroke, peripheral vascular disease, and heart failure. The interrelationship between metabolic dysfunction and cardiovascular disease is complex and multifactorial, involving hyperglycemia, insulin resistance, inflammation, and oxidative stress. Evidence indicates that endoplasmic reticulum (ER) stress and induction of the unfolded protein response (UPR) contribute to metabolic dysregulation and vascular dysfunction. However, the specific role of beta cell-derived UPR mediators, particularly C/EBP homologous protein (CHOP), in coordinating this interorgan axis between …

Phenotype Specific Nuclear Lamina Remodeling In Hipsc Derived Cardiomyocytes Bearing Tnnt2 Sarcomeric Variants, Isabella Leite Coscarella, Olalekan H. Usman, Lili Wang, Maicon Landim-Vieira, Lillian Wirstiuk, Amber N. Brown, Diego A. R. Zorio, Brian K. Washburn, Cynthia Vied, Bjorn C. Knollmann, Christopher Solís, Vitold E. Galkin, P. Bryant Chase, J. Travis Hinson, Jerome Irianto, Jose Renato Pinto

Department of Biomedical and Translational Sciences Faculty Publications

[Summary] Cardiomyocytes endure physical stress from the myocardium environment while generating their own mechanical strains. The force generated by sarcomeres is transmitted both longitudinally to adjacent sarcomeres and laterally to the cytoskeleton via intermediate filaments. This mechanical stimulus impacts other organelles, including the nucleus, thus playing a vital role in sensing and signaling nuclear adaptations. However, there is limited understanding of how changes in cardiac contractility affect nuclear mechanics. Here, we sought to investigate the effects of hyper- and hypo-contractility in nuclei of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) bearing TNNT2 pathogenic variants associated with hypertrophic (HCM) or dilated …