Intrauterine low-protein diet aggravates developmental abnormalities of the urinary system via the Akt/Creb3 pathway in Robo2 mutant mice

Abstract

The offspring of Robo2 mutant mice usually present with variable phenotypes of congenital anomalies of the kidney and urinary tract (CAKUT). An intrauterine low-protein diet can also cause CAKUT in offspring, dominated by the duplicated collecting system phenotype. A single genetic or environment factor can only partially explain the pathogenesis of CAKUT. The present study aimed to establish an intrauterine low-protein diet roundabout 2 ( Robo2) mutant mouse model and found that the intrauterine low-protein diet led to significantly increased CAKUT phenotypes in Robo2PB/+ mice offspring, dominant by a duplicated collecting system. At the same time, more ectopic and lower located ureteric buds (UBs) were observed in the intrauterine low-protein diet-fed Robo2 mutant mouse model, and the number of UB branches was reduced in the serum-free culture. During UB protrusion, intrauterine low-protein diet reduced the expression of Slit2/Robo2 in Robo2 mutant mice and affected the expression of glial cell-derived neurotrophic factor/Ret, which is a key molecule for metanephric development, with increasing phospho-Akt and phospho-cAMP responsive element-binding protein 3 activity and a reduction of apoptotic cells in embryonic day 11.5 UB tissues. The mechanism by which an intrauterine low-protein diet aggravates CAKUT in Robo2 mutant mice may be related to the disruption of Akt/cAMP responsive element-binding protein 3 signaling and a reduction in apoptosis in UB tissue.

Intrauterine Low-Protein Diet Exacerbates Abnormal Development of the Urinary System in <b><i>Gen1</i></b>-Mutant Mice

“…These offspring have multiple phenotypes of CAKUT, such as duplex kidney and hydronephrosis. In addition, to explore the interaction between genes and environment, a 6% protein isocaloric diet has been used to successfully construct an intrauterine low-protein isocaloric diet roundabout guidance receptor 2 (Robo2)-mutant mice [14]. The study confirmed that the intrauterine low-protein isocaloric diet increased the incidence of CAKUT in offspring of Robo2-mutant mice, accompanied by abnormally expressed key signaling molecules in metanephric development.…”

“…In the previous studies, our team preliminarily explored the interaction between genes and environment by constructing a Robo2-mutant mouse model in an adverse intrauterine environment and found that under the stimulation of a low-protein diet [14], the incidence of CA-KUT in the offspring of Robo2-mutant mice was significantly increased, and the phenotype was dominated by a duplicated collecting system, accompanied by the duplicated protrusion of UBs at an early stage, lower UB protrusions, and fewer UB branches. These findings suggested that an intrauterine adverse environment could increase the impact of Robo2 gene mutations to a certain extent, resulting in a significant increase in the risk of CA-KUT in the offspring.…”

“…Abnormal proliferation and apoptosis can affect UB protrusion and cause different phenotypes of CAKUT [25]. A low-protein diet can cause abnormal expression of key molecules in kidney development in Robo2-mutant mice and mainly affect key steps in meta- nephric development, such as UB protrusion, and mediate UB tissue apoptosis through Akt/Creb3 signaling [14]. How can low-protein diets as environmental stimuli significantly increase the risk of CAKUT in the offspring of Gen1 mutated mice?…”

“…After the vaginal plug was observed, the female mice were randomly divided into the experimental group and the Yu/Li/Tan/Chen/Zhai/Rao/Fang/Liu/Liu/ Wu/Xu/Shen Kidney Dis 2021;7:482-493 484 DOI: 10.1159/000516942 CON group. The experimental group was given 6% low-protein isocaloric diet (Double Lion Experimental Animal Feed Technology Co., Ltd.) throughout pregnancy [5,14], and the CON group was given the normal 22% protein diet (Suzhou Su-Hang Science and Technology Equipment Co., Ltd.) throughout pregnancy until natural birth. Both groups of pregnant mice had free access to food and water.…”

Robo2 and Gen1 Coregulate Ureteric Budding by Activating the MAPK/ERK Signaling Pathway in Mice

“…Several key regulatory genes involved in normal kidney development in humans and mice, including Roundabout Guidance Receptor 2 (ROBO2) and GEN1 Holliday Junction 5 ′ Flap Endonuclease (GEN1), attracted our attention because they play key roles in early urogenital tract development (12)(13)(14)(15)(16). ROBO2, as a human CAKUT gene with the OMIM-phenotype number (MIM#610878), a member of the immunoglobulin (Ig) superfamily of cell adhesion molecules (17), binds to its ligand SLIT2 and plays vital roles in maintaining the normal morphogenesis of the kidney.…”