Inhibition of MAPK/ERK pathway activation rescues congenital anomalies of the kidney and urinary tract (CAKUT) in Robo2PB/+ Gen1PB/+ mice

Congenital anomalies of the kidney and urinary tract (CAKUT) have been attributed to genetic and environmental factors. However, monogenic and copy number variations cannot sufficiently explain the cause of the majority of CAKUT cases. Multiple genes through various modes of inheritance may lead to CAKUT pathogenesis. We previously showed that Robo2 and Gen1 coregulated the germination of ureteral buds (UB), significantly increasing CAKUT incidence. Furthermore, MAPK/ERK pathway activation is the central mechanism of these two genes. Thus, we explored the effect of the MAPK/ERK inhibitor U0126 in the CAKUT phenotype in Robo2^PB/+Gen1^PB/+ mice. Intraperitoneal injection of U0126 during pregnancy prevented the development of the CAKUT phenotype in Robo2^PB/+Gen1^PB/+ mice. Additionally, a single dose of 30 mg/kg U0126 on day 10.5 embryos (E10.5) was most effective for reducing CAKUT incidence and ectopic UB outgrowth in Robo2^PB/+Gen1^PB/+ mice. Furthermore, embryonic kidney mesenchymal levels of p-ERK were significantly decreased on day E11.5 after U0126 treatment, along with decreased cell proliferation index PHH3 and ETV5 expression. Collectively, Gen1 and Robo2 exacerbated the CAKUT phenotype in Robo2^PB/+Gen1^PB/+ mice through the MAPK/ERK pathway, increasing proliferation and ectopic UB outgrowth.