Critical and distinct roles for key RET tyrosine docking sites in renal development

Area of Science:

• Developmental Biology
• Molecular Biology
• Genetics

Background:

• Congenital anomalies of kidneys and the lower urinary tract (CAKUT) have poorly understood molecular mechanisms.
• RET signaling plays a crucial role in kidney development, but its specificity is not fully elucidated.

Purpose of the Study:

• To investigate the molecular basis for GDNF-mediated RET signaling specificity in kidney development.
• To characterize the roles of different RET isoforms (RET9 and RET51) and their specific tyrosine docking sites in kidney development using murine models.

Main Methods:

• Generation and characterization of mice expressing specific human RET9 or RET51 isoforms with mutations in key tyrosine docking sites (Y981, Y1015, Y1062).
• Analysis of kidney and ureter development in these genetically modified mice.
• Assessment of downstream signaling pathways, including AKT/MAPK activation.

Main Results:

• Both RET9 and RET51 isoforms are largely redundant for normal kidney development in mice.
• Mutation of Y1015 in RET51 (RET51(Y1015F)) led to severe renal anomalies, including megaureters and multicystic kidneys, due to ureteric bud defects.
• Similar defects were observed in RET9(Y1015F) mice.
• Loss of RET9(Y1062)-mediated AKT/MAPK activation resulted in renal agenesis, while the equivalent mutation in RET51 had no effect.

Conclusions:

• Specific RET docking sites play differential and isoform-dependent roles in kidney development.
• The Y1015 site is critical for preventing ureteric bud abnormalities, while Y1062 is crucial for RET9-mediated signaling leading to kidney formation.
• These findings provide insights into the molecular basis of CAKUT and establish valuable murine models for further study.