Biology subjects

Ogle, B. M.

Publications and source records attributed to Ogle, B. M..

4 recordsLinked to original sources

bioRxiv2024

HCM-associated mutations in MYH6/7 drive pathologic expression of TGF-β1 in cardiomyocytes within weeks of developmental specification

Hypertrophic cardiomyopathy (HCM) is characterized by myocyte hypertrophy, sarcomere disarray, and myocardial fibrosis, leading to significant morbidity and mortality. As the most common inherited cardiomyopathy, HCM largely results from mutations in sarcomeric protein genes. Current treatments for HCM primarily focus on alleviating late-stage symptoms, with a critical gap in the detailed understanding of early-stage deficiencies that drive disease progression. We recently showed, in monolayers of cardiomyocytes derived from human induced pluripotent stem cells (hiPSCs) with MYH7 R723C and MYH6 R725C mutations, altered expression of several extracellular matrix (ECM)-related genes with associated defects in cardiomyocyte-ECM adhesion. To better evaluate the cardiomyocyte-ECM interface and pathological ECM dynamics in early-stage HCM, here we adopted a 3D engineered heart tissue (EHT) model containing both cardiomyocytes and fibroblasts, the primary contributor to ECM remodeling. Mutant EHTs showed aberrant cardiomyocyte distribution, augmented calcium handling, and force generation compared to controls. Altered proteoglycan deposition and increased phosphorylated focal adhesion kinase (pFAK) further indicated changes in ECM composition and connectivity. Elevated transforming growth factor beta-1 (TGF-{beta}1) secretion and a higher proportion of activated fibroblasts were identified in mutant EHTs, along with sustained TGF-{beta}1 transcription specifically in mutant cardiomyocytes. Remarkably, blocking TGF-{beta}1 receptor signaling reduced fibroblast activation and contraction force to control levels. This study underscores the early interplay of mutant hiPSC-CMs with fibroblasts, wherein mutant cardiomyocytes initiate fibroblast activation via TGF-{beta}1 overexpression, independent of the immune system. These findings provide a promising foundation for developing and implementing novel strategies to treat HCM well before the manifestation of clinically detectable fibrosis and cardiac dysfunction.

bioengineering↗

bioRxiv2024

Healthy human induced pluripotent stem cell-derived cardiomyocytes exhibit sex dimorphism even without the addition of hormones

Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CM) are a valuable cell type for studying human cardiac health and disease in vitro. However, it is not known whether hiPSC-CM display sex dimorphism and therefore whether sex should be incorporated as a biological variable in in vitro studies that include this cell type. To date, the vast majority of studies that utilize hiPSC-CM do not include both male and female sex nor stratify results based on sex because it is challenging to amass such a cohort of cells. Here we generated three female and three male hiPSC-lines from adult left ventricular cardiac fibroblasts as a resource for studying sex differences in in vitro cardiac models. We used this resource to generate hiPSC-CM and maintained them in basal media without exogenous hormones. Functional assessment of CM showed enhanced calcium handling in female-derived hiPSC-CM relative to male. Bulk RNA sequencing revealed over 300 differentially expressed genes (DEG) between male and female hiPSC-CM. Some of the DEG are X and Y-linked genes and many are implicated in cardiac health and disease including potassium channels which could account for net differences in calcium handling shown here. Gene ontology analysis of DEG showed distinct differences in pathways related to cardiac pathology including cell-cell adhesion, metabolic processes, and response to ischemic stress. These findings highlight the importance of considering sex as a variable when conducting studies to evaluate aspects of human cardiac health and disease related to cardiomyocyte function.

cell biology↗

bioRxiv2022

Myosin Heavy Chain Converter Domain Mutations Drive Early-Stage Changes in Extracellular Matrix Dynamics in Hypertrophic Cardiomyopathy

More than 60% of hypertrophic cardiomyopathy (HCM)-causing mutations are found in the gene loci encoding cardiac myosin-associated proteins including myosin heavy chain (MHC) and myosin binding protein C (MyBP-C). Moreover, patients with more than one independent HCM mutation may be at increased risk for more severe disease expression and adverse outcomes. However detailed mechanistic understanding, especially at early stages of disease progression, is limited. To identify early-stage HCM triggers, we generated single (MYH7 c.2167C>T [R723C] with a known pathogenic significance in the MHC converter domain) and double (MYH7 c.2167C>T [R723C]; MYH6 c.2173C>T [R725C] with unknown significance) myosin gene mutations in human induced pluripotent stem cells (hiPSCs) using a base-editing strategy. Cardiomyocytes (CMs) derived from hiPSCs with either single or double mutation exhibited phenotypic characteristics consistent with later-stage HCM including hypertrophy, multinucleation, altered calcium handling, metabolism and arrhythmia. We then probed mutant CMs at time points prior to the detection of known HCM characteristics. We found MYH7/MYH6 dual mutation dysregulated extracellular matrix (ECM) remodeling, altered integrin expression, and interrupted cell-ECM adhesion by limiting the formation of focal adhesions. These results point to a new phenotypic feature of early-stage HCM and reveal novel therapeutic avenues aimed to delay or prohibit disease onset.

bioengineering↗

bioRxiv2022

The HH-GLI2-CKS1B network regulates the proliferation-to-maturation transition of human cardiomyocytes

Cardiomyocyte (CM) proliferation and maturation are highly linked processes, however, the extent to which these processes are controlled by a single signaling axis is unclear. Here, we find the Hedgehog (HH)-GLI2-CKS1B cascade regulates the transition between proliferation and maturation in hiPSC-CMs. Initially, we found a significant enrichment of GLI2-signaling in CMs from patients with ischemic heart failure (HF) or dilated-cardiomyopathy (DCM), indicating initiation of fetal programs in the stressed heart. Developmentally, we showed downregulation of GLI-signaling in adult human CM, adult murine CM, and in late-stage hiPSC-CM. In early-stage, proliferative hiPSC-CM, inhibition of Hh- or GLI-proteins enhanced CM maturation. Mechanistically, we identified CKS1B, a new effector of GLI2 and showed that GLI2 binds the CKS1B promoter to regulate its expression. CKS1B overexpression in late-stage hiPSC-CMs led to increased proliferation with loss of maturation. Thus, the Hh-GLI2-CKS1B axis regulates the proliferation-maturation transition and provides targets to enhance cardiac tissue engineering and regenerative therapies.

developmental biology↗