Multiple secretoglobin 1A1 genes are differentially expressed in horses

Area of Science:

• Genomics
• Molecular Biology
• Comparative Mammalian Genetics

Background:

• Secretoglobin 1A1 (SCGB 1A1) is a key airway protein, typically a single gene copy in mammals.
• Equine genome analysis suggests multiple SCGB1A1 gene copies in horses.
• Reduced SCGB 1A1 levels are observed in horses with recurrent airway obstruction (RAO).

Purpose of the Study:

• Investigate the presence and expression of distinct SCGB1A1 genes in horses.
• Determine differential gene expression in various tissues and in the context of RAO.
• Analyze cell-specific protein expression of SCGB1A1.

Main Methods:

• Equine genome analysis to identify SCGB1A1 gene copies.
• Bioinformatic analysis of gene sequences and mutations.
• RT-PCR and endpoint-limiting dilution PCR to detect and differentiate transcripts.
• Immunohistochemistry to assess protein expression in tissues.

Main Results:

• Identified three SCGB1A1 gene copies on equine chromosome 12.
• Two genes (SCGB1A1 and SCGB1A1A) are expressed, while SCGB1A1P appears to be a pseudogene.
• Strong expression of SCGB1A1 and SCGB1A1A detected in lung, uterus, Fallopian tube, and mammary gland.
• Altered SCGB1A1A to SCGB1A1 expression ratio observed in RAO-affected horses.

Conclusions:

• This study reports the first instance of three SCGB1A1 genes in a mammal.
• The two expressed genes encode proteins with potentially different functions.
• Altered gene expression ratios in RAO indicate cell/tissue-specific regulation and roles, potentially impacting lung and reproductive conditions.