No abstract

GATA5 belongs to the GATA family of transcription factors characterized by highly evolutionarily conserved zinc-finger DNA-binding domains. Mouse models have implicated a role of GATA5 during mammalian embryogenesis, including proper heart development and gender-specific regulation of female genitourinary tract formation. Previous studies have found an association of heterozygous missense alterations in GATA5 with a broad variety of heart diseases; however, the clinical relevance of the identified susceptibility variants has remained unclear. Here, we report on a girl with hydrops fetalis, congenital heart defects, clitoromegaly and postnatally increased 17-hydroxyprogesterone levels. By trio whole-exome sequencing, we identified compound heterozygous missense mutations, p.Ser19Trp and p.Arg202Gln, in GATA5 as putative disease-causing alterations. The identified mutations fail to rescue the cardia bifida phenotype in a zebrafish model, mislocalize to subnuclear foci when transiently transfected in HEK293 cells and possess less transcriptional activity. In addition to demonstrating the pathogenicity of identified mutations, our findings show that GATA5 mutations, in addition to heart diseases, can result in congenital abnormalities of the female genitourinary tract in humans.

The evolutionarily conserved DRY motif at the end of the third helix of rhodopsin-like, class-A G protein-coupled receptors (GPCRs) is a major regulator of receptor stability, signaling activity, and β-arrestin-mediated internalization. Substitution of the DRY arginine with histidine in the human vasopressin receptor results in a loss-of-function phenotype associated with diabetes insipidus. The analogous R150H substitution of the DRY motif in zebrafish sphingosine-1 phosphate receptor 2 (S1p2) produces a mutation, miles apart m93 (milm93), that not only disrupts signaling but also impairs heart field migration. We hypothesized that constitutive S1p2 desensitization is the underlying cause of this strong zebrafish developmental defect. We observed in cell assays that the wild-type S1p2 receptor is at the cell surface whereas in distinct contrast the S1p2 R150H receptor is found in intracellular vesicles, blocking G protein but not arrestin signaling activity. Surface S1p2 R150H expression could be restored by inhibition of G protein-coupled receptor kinase 2 (GRK2). Moreover, we observed that β-arrestin 2 and GRK2 colocalize with S1p2 in developing zebrafish embryos and depletion of GRK2 in the S1p2 R150H miles apart zebrafish partially rescued cardia bifida. The ability of reduced GRK2 activity to reverse a developmental phenotype associated with constitutive desensitization supports efforts to genetically or pharmacologically target this kinase in diseases involving biased GPCR signaling.

No abstract