Biology subjects

Gelb, B.

Publications and source records attributed to Gelb, B..

3 recordsLinked to original sources

bioRxiv2021

Sequential defects in cardiac lineage commitment and maturation cause hypoplastic left heart syndrome

BackgroundComplex molecular programs in specific cell lineages govern human heart development. Hypoplastic left heart syndrome (HLHS) is the most common and severe manifestation within the spectrum of left ventricular outflow tract obstruction defects occurring in association with ventricular hypoplasia. The pathogenesis of HLHS is unknown, but hemodynamic disturbances are assumed to play a prominent role. MethodsTo identify perturbations in gene programs controlling ventricular muscle lineage development in HLHS, we performed: i) whole-exome sequencing of 87 HLHS parent-offspring trios, ii) nuclear transcriptomics of cardiomyocytes from ventricles of 4 patients with HLHS and 15 controls at different stages of heart development, iii) single cell RNA sequencing and iv) 3D modeling in iPSCs from 3 patients with HLHS and 3 controls. ResultsGene set enrichment and protein network analyses of damaging de-novo mutations and dysregulated genes from ventricles of patients with HLHS suggested alterations in specific gene programs and cellular processes critical during fetal ventricular cardiogenesis, including cell-cycle and cardiomyocyte maturation. Single-cell and 3D modeling with iPSCs demonstrated intrinsic defects in the cell-cycle/UPR/autophagy hub resulting in disrupted differentiation of early cardiac progenitor lineages leading to defective cardiomyocyte-subtype differentiation/maturation in HLHS. Additionally, premature cell-cycle exit of ventricular cardiomyocytes from HLHS patients prevented normal tissue responses to developmental signals for growth leading to multinucleation/polyploidy, accumulation of DNA damage, and exacerbated apoptosis, all potential drivers of left ventricular hypoplasia in absence of hemodynamic cues. ConclusionsOur results highlight that despite genetic heterogeneity in HLHS, many mutations converge on sequential cellular processes primarily driving cardiac myogenesis, suggesting novel therapeutic approaches.

developmental biology↗

bioRxiv2020

Drosophila RASopathy Models Identify Disease Subtype Differences and Biomarkers of Drug Efficacy

RASopathies represent a family of mostly autosomal dominant diseases that are caused by missense variants in the RAS/MAPK pathway. In aggregate, they are among the more common Mendelian disorders. They share overlapping pathologies that include structural birth and developmental defects that affect the heart, craniofacial and skeletal, lymphatic, and nervous systems. Variants in different genes--including those encoding KRAS, NRAS, BRAF, RAF1, and SHP2--are associated with overlapping but distinct phenotypes. Here, we report an analysis of 13 Drosophila transgenic lines, each expressing a different human disease isoform associated with a form of RASopathy. Similar to their human counterparts, each Drosophila line has common aspects but also important phenotypic distinctions including signaling pathways as well as response to therapeutics. For some lines, these differences represent activation of pathways outside the core RAS signaling pathway including the Hippo and SAPK/JNK signaling networks. We identified two classes of clinically relevant drugs, statins and histone deacetylase inhibitors, that improved viability across most RASopathy lines; in contrast, several canonical RAS pathway inhibitors proved poorly effective against, e.g., SHP2-expressing lines encoded by PTPN11. Our study provides a whole animal platform for comparison of a large number of RASopathy-associated variants. Among these variants we have identified differences in tissue phenotypes, in activation signaling pathways in biomarkers of disease progression and drug efficacy, and suggest drug classes that can be tolerated over long treatment periods for consideration in broad RASopathy trials.

developmental biology↗

bioRxiv2019

Complex Autoinflammatory Syndrome Unveils Fundamental Principles of JAK1 Transcriptional and Biochemical Function

Autoinflammatory disease can result from monogenic errors of immunity. We describe herein the first example of a patient with early-onset widespread autoinflammation resulting from a mosaic, heterozygous, gain-of-function mutation (S703I) in JAK1, encoding a kinase essential for signaling downstream of over twenty-five cytokines. By first-of-its-kind custom single-cell RNA sequencing, we examine mosaicism with single cell resolution. We uncover that JAK1 transcription is predominantly restricted to a single allele across different immune cells, introducing the concept of a mutational \"transcriptotype\" that differs from the genotype. Functionally, the S703I mutation not only increased JAK1 kinase activity, but also resulted in transactivation of partnering JAKs, independently of its catalytic domain. Further, S703I JAK1 was not solely hypermorphic for cytokine signaling, but neomorphic as well, as it enabled downstream signaling cascades not canonically mediated by JAK1. Given these results, the patient was treated with tofacitinib, a JAK inhibitor, which led to rapid resolution of her clinical disease. Together, these findings represent an unprecedented degree of personalized medicine with the concurrent discovery of fundamental biological principles.

immunology↗