Defining the Polycystin Pharmacophore Through HTS & Computational Biophysics.

Background And Purpose: Polycystins (PKD2, PKD2L1) are voltage-gated and Ca-modulated members of the transient receptor potential (TRP) family of ion channels. Loss of PKD2L1 expression results in seizure-susceptibility and autism-like features in mice, whereas variants in PKD2 cause autosomal dominant polycystic kidney disease. Despite decades of evidence clearly linking their dysfunction to human disease and demonstrating their physiological importance in the brain and kidneys, the polycystin pharmacophore remains undefined.

Transient titin-dependent ventricular defects during development lead to adult atrial arrhythmia and impaired contractility.

Developmental causes of the most common arrhythmia, atrial fibrillation (AF), are poorly defined, with compensation potentially masking arrhythmic risk. Here, we delete 9 amino acids (Δ9) within a conserved domain of the giant protein titin's A-band in zebrafish and human-induced pluripotent stem cell-derived atrial cardiomyocytes (hiPSC-aCMs). We find that zebrafish embryos' cardiac morphology is perturbed and accompanied by reduced functional output, but ventricular function recovers within days.

Molecular and cellular context influences SCN8A variant function.

Pathogenic variants in SCN8A, which encodes the voltage-gated sodium (NaV) channel NaV1.6, associate with neurodevelopmental disorders, including developmental and epileptic encephalopathy. Previous approaches to determine SCN8A variant function may be confounded by use of a neonatally expressed, alternatively spliced isoform of NaV1.

Independent compartmentalization of functional, metabolic, and transcriptional maturation of hiPSC-derived cardiomyocytes.

Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) recapitulate numerous disease and drug response phenotypes, but cell immaturity may limit their accuracy and fidelity as a model system. Cell culture medium modification is a common method for enhancing maturation, yet prior studies have used complex media with little understanding of individual component contribution, which may compromise long-term hiPSC-CM viability. Here, we developed high-throughput methods to measure hiPSC-CM maturation, determined factors that enhanced viability, and then systematically assessed the contribution of individual maturation medium components.