Ureteric branching morphogenesis in BMP4 heterozygous mutant mice

Area of Science:

• Developmental Biology
• Molecular Biology
• Genetics

Background:

• Bone morphogenetic protein 4 (BMP4) plays a role in kidney development.
• BMP4 influences ureteric branching morphogenesis and can amplify developmental asymmetries.
• Understanding BMP4's role is crucial for comprehending kidney formation and potential developmental defects.

Purpose of the Study:

• To investigate the impact of reduced endogenous BMP4 levels on ureteric branching morphogenesis in developing mouse kidneys.
• To determine if reduced BMP4 levels alter the response to exogenous BMP4.
• To analyze the effect of BMP4 on renal asymmetry.

Main Methods:

• Utilized BMP4/lacZ heterozygous mice to study reduced endogenous BMP4 expression.
• Employed in vitro culture of embryonic day 12.5 metanephroi for 48 hours.
• Administered exogenous recombinant human BMP4 (rhBMP4) and analyzed ureteric branching using 3D imaging and real-time PCR for BMP4 mRNA levels.

Main Results:

• BMP4 heterozygous mice showed significantly reduced BMP4 mRNA levels but exhibited normal ureteric branching morphogenesis compared to wildtype controls.
• Both BMP4 heterozygous and wildtype metanephroi treated with exogenous BMP4 displayed reduced ureteric length, branch number, and volume, with increased average branch length.
• A notable anterior-posterior asymmetry in ureteric development was observed in BMP4-treated kidneys, a phenomenon also present, though less pronounced, in control kidneys.

Conclusions:

• Reduced endogenous BMP4 levels do not impede normal ureteric branching morphogenesis in developing mouse kidneys.
• The inhibitory effects of exogenous BMP4 on ureteric branching and the amplification of renal asymmetry are not altered by reduced endogenous BMP4 levels.
• Kidney development and asymmetry are influenced by BMP4, but compensatory mechanisms exist for reduced endogenous levels.