Regulation of Horn Development in Hu Sheep Involves RXFP2 Expression and Hormonal Signaling Independent of the...

Area of Science:

• Animal Genetics
• Developmental Biology
• Sheep Genomics

Background:

• The RXFP2 gene's 3'-UTR insertion is linked to polled sheep, but horned individuals with this insertion exist.
• This suggests additional regulatory factors influence horn morphology in sheep (Ovis aries).

Purpose of the Study:

• Investigate the genetic and regulatory mechanisms of horn development in sheep.
• Clarify the role of RXFP2 and its associated signaling pathways in horn morphogenesis.
• Identify factors contributing to horn presence in breeds typically lacking horns.

Main Methods:

• Genome-wide association analysis to identify horn-associated quantitative trait loci (QTL).
• Gene expression analysis (RNA-seq) in multiple sheep breeds to assess RXFP2 expression.
• Hormonal profiling to examine the INSL3/RXFP2 signaling axis and interactions with testosterone.

Main Results:

• A significant horn-associated QTL on chromosome 10 was identified.
• The 1.78-kb insertion in RXFP2's 3'-UTR is associated with horn status across breeds.
• Elevated RXFP2 expression correlates with horn development, even in homozygous insertion individuals.
• The INSL3/RXFP2 signaling axis, interacting with testosterone, is crucial for horn morphogenesis.

Conclusions:

• Sheep horn development is regulated by both structural RXFP2 variations and its transcriptional/hormonal control.
• Horn formation has a polygenic basis involving complex interactions.
• Findings provide insights for selective breeding strategies in polled sheep populations.