Galloway-Mowat syndrome: New insights from bioinformatics and expression during Xenopus embryogenesis

Galloway-Mowat syndrome (GAMOS) is a rare developmental disease. Patients suffer from congenital brain anomalies combined with renal abnormalities often resulting in an early-onset steroid-resistant nephrotic syndrome. The etiology of GAMOS has a heterogeneous genetic contribution. Mutations in more than 10 different genes have been reported in GAMOS patients. Among these are mutations in four genes encoding members of the human KEOPS (kinase, endopeptidase and other proteins of small size) complex, including OSGEP, TP53RK, TPRKB and LAGE3. Until now, these components have been functionally mainly investigated in bacteria, eukarya and archaea and in humans in the context of the discovery of its role in GAMOS, but the KEOPS complex members' expression and function during embryogenesis in vertebrates is still unknown. In this study, in silico analysis showed that both gene localization and the protein sequences of the three core KEOPS complex members Osgep, Tp53rk and Tprkb are highly conserved across different species including Xenopus laevis. In addition, we examined the spatio-temporal expression pattern of osgep, tp53rk and tprkb using RT-PCR and whole mount in situ hybridization approaches during early Xenopus development. We observed that all three genes were expressed during early embryogenesis and enriched in tissues and organs affected in GAMOS. More precisely, KEOPS complex genes are expressed in the pronephros, but also in neural tissue such as the developing brain, eye and cranial cartilage. These findings suggest that the KEOPS complex plays an important role during vertebrate embryonic development.