Biology subjects

Sheikh, F.

Publications and source records attributed to Sheikh, F..

4 recordsLinked to original sources

bioRxiv2026

Sonogenetic control of cardiomyocytes and cardiac pacing using exogenous Transient Receptor Potential A1 channels

Electronic cardiac pacemakers are the standard of care for treating arrhythmias but, even for wireless pacemakers, they require an intracardiac implant procedure and are invasive. Lead-related complications, including life-threatening infections, and limited suitability in pediatric patients restrict pacemaker use. Biological pacing has emerged as a hardware-free alternative, leveraging cell reprogramming approaches to generate pacemaker-like cardiomyocytes. Despite progress, biological strategies face challenges related to complex signaling pathways, intercellular coupling, durability of effect, efficacy, and safety. In addition, once ion channels or cells are implanted, biological pacemakers offer limited real-time programmability, whereas electronic pacemakers enable continuous adjustment of pacing output based on cardiac performance. Here we propose a hybrid approach that combines genetic sensitization with external control by exploring the feasibility of sonogenetic cardiac pacing. We express the ultrasound-sensitive ion channel hsTRPA1 in cardiomyocytes and use noninvasive ultrasound to modulate channel activity and cardiac function. Using calcium imaging, we show that hsTRPA1 potentiates ultrasound-evoked responses in cardiomyocytes. Furthermore, cardiac expression of hsTRPA1 in mice increases heart rate in response to ultrasound delivered noninvasively through the intact chest, without evidence of a thermal mechanism under the conditions tested. Together, these results establish a proof of concept for sonogenetic cardiac pacing and define an initial acoustic and genetic parameter space compatible with preserving baseline cardiac function. More broadly, this work positions sonogenetics as a minimally invasive, wireless strategy for cardiac rhythm control and motivates future optimization and safety studies toward translation.

bioengineering↗

bioRxiv2025

Fosl2 regulates the transition from parietal epithelial cells to myofibroblasts in the kidney

Activation and proliferation of parietal epithelial cells (PECs), located along the inner rim of Bowmans capsule, drives disease progression in subtypes of glomerulonephritis and focal segmental glomerulosclerosis. In examining the mechanisms contributing to PEC activation two established mouse models were utilized in this study, nephrotoxic serum nephritis (transient model) and podocyte-specific Klf4 knockout (progressive model). A role for transcription factor FRA2 (Fosl2) was uncovered through single nuclear multiomic approaches relating to the regulation of PEC transcriptional/chromatin dynamics. Co-immunoprecipitation followed by mass spectrometry assessed the FRA2 protein interactome in cultured PECs, revealing a potential role for FRA2 in alternative splicing. Fosl2 expression was then blunted through CRISPR-Cas9 gene editing in cultured PECs, revealing reduced proliferative capacity and the downregulation of myofibroblast markers. In-vivo genetic lineage tracing of PECs after nephrotoxic serum revealed PEC-to-myofibroblast trans-differentiation events. Finally, immunostaining of human kidney biopsies with varied subtypes of glomerulonephritis confirmed Fosl2 expression in activated PECs within crescentic lesions, with single cell deconvolution strategies assigning PEC-skewed proportion ratios to bulk RNA-seq patient data from the NEPTUNE consortium. These results suggest that FRA2 (Fosl2) directs a conserved molecular program of PEC-specific responses in subtypes of glomerulonephritis and focal segmental glomerulosclerosis.

pathology↗

bioRxiv2025

Association of RhoGEF Ect2 with Desmoplakin Supports RhoA Activity at Intercellular Junctions: Implications for Carvajal Disease

Desmoplakin (DP) is an essential component of the desmosomal adhesion complex, tethering intermediate filaments to sites of intercellular adhesion to confer mechanical integrity to tissues. As a frequent target for mutation in cardiocutaneous syndromes that vary widely in phenotype, DPs roles as a signaling hub are rapidly emerging. Here, we identify the RhoGEF Ect2 as a previously unappreciated binding partner of the desmosomal protein DP. DP is required for the localization of Ect2 to keratinocyte desmosomes and cardiac intercalated discs in vitro and in vivo, where it maintains active RhoA (Rho-GTP) at the membrane. We demonstrate further that Ect2 activity is supported by PKC in a DP-dependent manner in cardiac myocytes. Finally, a truncated form of DP expressed in patients with Carvajal syndrome associated with severe cardiocutaneous defects is impaired in its ability to bind and localize Ect2 to cell junctions in cardiomyocytes and keratinocytes isolated from patients. Our findings delineate an important relationship between a component of the desmosome and a critical regulator of actin cytoskeletal remodeling that could have widespread implications for understanding cardiac and cutaneous health and disease pathogenesis.

cell biology↗

bioRxiv2022

Combined loss of obscurin and obscurin-like 1 in murine hearts results in impaired diastolic dysfunction, altered metabolism and deregulated mitophagy.

Muscle proteins of the obscurin protein family play important roles in sarcomere organization, sarcoplasmic reticulum (SR) and T-tubule architecture and function. However, their precise molecular functions and redundancies between protein family members as well as their involvement in cardiac diseases remain to be fully understood. To investigate the functional roles of obscurin and its close homologue obscurin-like 1 (Obsl1) in the heart, we generated and analyzed knockout mice for obscurin, Obsl1, as well as obscurin/Obsl1 double-knockouts (dKO). We show that dKO mice are viable but show postnatal deficits in cardiac muscle SR and mitochondrial architecture and function at the microscopic, biochemical and cellular level. Altered SR structure resulted in perturbed calcium cycling, while mitochondrial ultrastructure deficits were linked to decreased levels of Chchd3, a Micos complex protein. Hearts of dKO mice also show increased expression of Atg4d, a novel Obsl1 interacting protein, resulting in abnormal mitophagy and increased unfolded protein response. At the physiological level, loss of obscurin and Obsl1 resulted in a profound delay of cardiac relaxation, associated with metabolic signs of heart failure. Taken together, our data suggest that obscurin and Obsl1 play crucial roles in cardiac SR structure, calcium cycling, mitochondrial function, turnover and metabolism.

cell biology↗