Heinrich, P. | Search bioRxiv

bioRxiv2024

Tissue-adapted Tregs harness inflammatory signals to promote intestinal repair from therapy-related injury

Intestinal stem cells (ISC) promote tissue repair after genotoxic or immune-mediated injury. However, ISCs are particularly sensitive to various stressors and primary targets of overwhelming immune responses such as interferon-{gamma} (IFN{gamma})-mediated killing. In mouse models of gut damage and biopsies from patients having undergone allo-hematopoietic stem cell transplantation, we observed IFNy expression by intestinal Treg cells. Treg cells leverage combined IFN{gamma} and interleukin 10 (IL-10) stimulation of ISCs to nurture the growth of intestinal organoids through the activation of the mTORC1 and Myc pathways. Similarly, Treg cells or the combined addition of recombinant IFN{gamma} and IL-10 promote the regeneration of organoids after irradiation. Exposure of organoids to Wnt- or EGF-free culture conditions revealed distinct growth factor-like properties of IFN{gamma} and IL-10. While IFN{gamma} induced epithelial proliferation and differentiation, combined addition of IFN{gamma} and IL-10 led to balanced proliferation, ensuring ISC maintenance. Our results uncover a context-dependent role of inflammatory signaling in ISC, through which Treg cells promote epithelial repair.

immunology↗

bioRxiv2023

Multi-scale models reveal hypertrophic cardiomyopathy MYH7 G256E mutation drives hypercontractility and elevated mitochondrial respiration

RationaleOver 200 mutations in the sarcomeric protein {beta}-myosin heavy chain (MYH7) have been linked to hypertrophic cardiomyopathy (HCM). However, different mutations in MYH7 lead to variable penetrance and clinical severity, and alter myosin function to varying degrees, making it difficult to determine genotype-phenotype relationships, especially when caused by rare gene variants such as the G256E mutation. ObjectiveThis study aims to determine the effects of low penetrant MYH7 G256E mutation on myosin function. We hypothesize that the G256E mutation would alter myosin function, precipitating compensatory responses in cellular functions. MethodsWe developed a collaborative pipeline to characterize myosin function at multiple scales (protein to myofibril to cell to tissue). We also used our previously published data on other mutations to compare the degree to which myosin function was altered. ResultsAt the protein level, the G256E mutation disrupts the transducer region of the S1 head and reduces the fraction of myosin in the folded-back state by 50.9%, suggesting more myosins available for contraction. Myofibrils isolated from hiPSC-CMs CRISPR-edited with G256E (MYH7WT/G256E) generated greater tension, had faster tension development and slower early phase relaxation, suggesting altered myosin-actin crossbridge cycling kinetics. This hypercontractile phenotype persisted in single-cell hiPSC-CMs and engineered heart tissues. Single-cell transcriptomic and metabolic profiling demonstrated upregulation of mitochondrial genes and increased mitochondrial respiration, suggesting altered bioenergetics as an early feature of HCM. ConclusionsMYH7 G256E mutation causes structural instability in the transducer region, leading to hypercontractility across scales, perhaps from increased myosin recruitment and altered crossbridge cycling. Hypercontractile function of the mutant myosin was accompanied by increased mitochondrial respiration, while cellular hypertrophy was modest in the physiological stiffness environment. We believe that this multi-scale platform will be useful to elucidate genotype-phenotype relationships underlying other genetic cardiovascular diseases.

molecular biology↗