Biology subjects

Patel, S. N.

Publications and source records attributed to Patel, S. N..

3 recordsLinked to original sources

bioRxiv2025

Effects of Sodium Glucose Co-Transporter Inhibitors on Work in Human Hypertrophic Cardiomyopathy Living Myocardial Slices

BackgroundDisease modifying therapies for hypertrophic cardiomyopathy (HCM) remain a prevailing unmet need. Human-based experimental platforms capable of controlled manipulation of preload and afterload can distinguish direct myocardial and systemic effects and facilitate development of targeted cardiac therapeutics. Sodium glucose cotransporter inhibitors (SGLTi) may directly affect cardiac contractility, potentially related to increased ketone availability. These effects have not been adequately studied in human HCM myocardium under defined loading conditions. AimsWe sought to establish human living myocardial slices (LMS) as a platform to interrogate load-dependent myocardial mechanics in HCM and to quantify the acute effects of metabolic and pharmacologic interventions--including SGLTi--on myocardial work under physiologic loading conditions. MethodsHuman myocardial tissue was procured from non-failing donor hearts or individuals with HCM undergoing septal myectomy. Freshly prepared human LMS were mechanically tested to generate biomimetic work loops across a range of physiologic preloads and afterloads in either glucose-only fuel or glucose supplemented with ketone. Following baseline measurements, slices were loaded with drug (isoproterenol, mavacamten, sotagliflozin, or empagliflozin) or vehicle (DMSO) and work loop analysis was repeated, allowing each slice to serve as its own control. Mixed effects linear regression models incorporating random effects for heart and slice and fixed effects for clinical characteristics evaluated determinants of myocardial work and drug response across loading conditions. ResultsA total of 120 LMS from 32 individuals (16 non-failing and 16 HCM) were analyzed. At baseline, myocardial work was positively associated with younger age, hypertension, and ejection fraction. Ketone supplementation augmented work and work-strain slope particularly in HCM LMS at high afterloads. We validated our drug testing methodology by demonstrating increased work with known positive inotrope isoproterenol, decreased work with negative inotrope mavacamtem most pronounced in HCM LMS, and a null effect of DMSO. Acute exposure to SGLTi sotagliflozin and empagliflozin directly reduced myocardial work, with increased potency of sotagliflozin at high afterloads. ConclusionsOur LMS platform enables assessment of myocardial mechanics across controlled loading conditions and is an ideal platform to rigorously phenotype human myocardial tissue and interrogate direct effects of pharmacologic intervention. We demonstrate that SGLTi and ketones have distinct and discordant effects on human myocardial contractility.

physiology↗

bioRxiv2023

Noncanonical interactions and conformational dynamics in cargo-Pex5-Pex14 ternary complex for peroxisomal import

Peroxisomes are membrane enclosed organelles hosting diverse metabolic processes in eukaryotic cells. Having no protein synthetic abilities, peroxisomes import all required enzymes from the cytosol through a peroxin (pex) import system. Peroxisome targeting sequence 1 (PTS1)-tagged cargo is recognized by soluble receptor, Pex5. The cargo-Pex5 complex docks at the peroxisomal membrane translocon, composed of Pex14 and Pex13, facilitating translocation into the peroxisomal lumen. Despite its significance, the structural basis of this process is poorly understood. Here, we present a cryo-electron microscopy (cryo-EM) structure of cargo-Pex5-Pex14 ternary complex from Trypanosoma cruzi, the causative agent of human Chagas disease. The atomic model of the Pex5 (residues 327-653) bound to malate dehydrogenase (MDH, cargo) tetramer and Pex14NTD (residues 21-85) reveals dynamic motions and secondary interfaces. Specifically, we observe a swinging motion of Pex5 at the MDH-Pex5 interface. Additionally, the noncanonical contact surfaces are observed at the MDH-Pex5 and Pex5-Pex14 interfaces. Mutational analysis of the former interface indicates that it does not significantly enhance the affinity, underscoring the dynamic nature of cargo-Pex5 interactions. The latter interface constitutes an extended binding site of Pex14NTD over Pex5. We discuss the implications of these findings for understanding peroxisomal transport mechanisms. HIGHLIGHTSO_LIThe structure of the peroxisomal import ternary complex (MDH-Pex5TPR-Pex14NTD) is determined using cryo-EM. C_LIO_LIPex5 interface with the cargo (MDH) is characterized by significant conformational dynamics. C_LIO_LIThe extended binding site of Pex14NTD on Pex5 is revealed. C_LI

biochemistry↗

bioRxiv2020

Evolutionary and structural analyses of SARS-CoV-2 D614G spike protein mutation now documented worldwide

The COVID-19 pandemic, caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), was declared on March 11, 2020 by the World Health Organization. As of the 31st of May, 2020, there have been more than 6 million COVID-19 cases diagnosed worldwide and over 370,000 deaths, according to Johns Hopkins. Thousands of SARS-CoV-2 strains have been sequenced to date, providing a valuable opportunity to investigate the evolution of the virus on a global scale. We performed a phylogenetic analysis of over 1,225 SARS-CoV-2 genomes spanning from late December 2019 to mid-March 2020. We identified a missense mutation, D614G, in the spike protein of SARS-CoV-2, which has emerged as a predominant clade in Europe (954 of 1,449 (66%) sequences) and is spreading worldwide (1,237 of 2,795 (44%) sequences). Molecular dating analysis estimated the emergence of this clade around mid-to-late January (10 - 25 January) 2020. We also applied structural bioinformatics to assess D614G potential impact on the virulence and epidemiology of SARS-CoV-2. In silico analyses on the spike protein structure suggests that the mutation is most likely neutral to protein function as it relates to its interaction with the human ACE2 receptor. The lack of clinical metadata available prevented our investigation of association between viral clade and disease severity phenotype. Future work that can leverage clinical outcome data with both viral and human genomic diversity is needed to monitor the pandemic.

bioinformatics↗