Testing the Ret and Sema3d genetic interaction in mouse enteric nervous system development.

Area of Science:

• Developmental Biology
• Genetics
• Neuroscience

Background:

• Multigenic disorders often result from interactions between multiple susceptibility genes.
• Hirschsprung disease is a complex genetic disorder affecting the enteric nervous system.

Purpose of the Study:

• To investigate potential genetic interactions between Ret and Sema3d, two known Hirschsprung disease susceptibility genes.
• To evaluate the impact of combined Ret and Sema3d loss-of-function on mouse survival, intestinal innervation, and gene expression.

Main Methods:

• Generation of mice with varying Ret and Sema3d genotypes using double null heterozygote crosses.
• Assessment of survival rates at different developmental stages (embryonic day 12.5, birth, weaning).
• Analysis of myenteric plexus presence via acetylcholinesterase staining and intestinal transcriptome profiling using RNA-sequencing.

Main Results:

• Survival rates were not influenced by the genotype at the Sema3d locus in Ret mutant mice, or vice versa.
• Loss of the myenteric plexus was exclusively observed in Ret null homozygotes, independent of Sema3d genotype.
• RNA-sequencing revealed significant gene expression changes in Ret null homozygotes but not in Sema3d null homozygotes, with no evidence of major gene interaction.

Conclusions:

• The study found no evidence of genetic interaction between Ret and Sema3d influencing survival, myenteric plexus formation, or the intestinal transcriptome in the mouse models used.
• These findings suggest that Ret and Sema3d may act independently or through pathways not assessed by the employed null alleles and assays in the context of Hirschsprung disease.