Molecular Characterization of ALDH1A1 and Its Association with Secondary Hair Follicle Stem Cell Proliferation in Liaoning Cashmere Goats

Aldehyde dehydrogenase 1 family member A1 (ALDH1A1) is broadly expressed in mammalian tissues and is a key enzyme in retinoic acid (RA) biosynthesis, a process closely linked to hair follicle regeneration. Its expression pattern and function in cashmere goats, however, remain poorly defined. In this study, we isolated and characterized the full-length open reading frame (ORF) of ALDH1A1 cDNA from Liaoning cashmere goat skin, examined its expression across multiple tissues and seasonally assigned hair-cycle periods, and evaluated its effects on the proliferation of secondary hair follicle stem cells (SHFSCs). Nine male goats were used for seasonal skin sampling (n = 3 per period), primary SHFSCs were derived from one additional female donor (n = 1), and cell-based assays were independently repeated three times. The ALDH1A1 ORF was 1506 bp and encoded a 501-amino-acid protein; its nucleotide sequence shared 90.07–99.14% identity with corresponding mammalian sequences. Conserved-domain analysis assigned the goat ALDH1A1 protein to the aldehyde dehydrogenase superfamily (ALDH-SF), and phylogenetic analysis showed that the experimentally obtained sequence clustered with the Capra hircus reference sequence and other ruminant ALDH1A1 sequences. Among the tissues examined, ALDH1A1 transcripts were most abundant in skin, and both mRNA and protein levels in skin were highest during the seasonally assigned anagen period. In SHFSCs, ALDH1A1 overexpression increased multiple proliferation-related readouts, whereas knockdown produced the opposite changes. Overall, these findings characterize goat ALDH1A1 at the molecular and functional levels and support an association between ALDH1A1 perturbation and proliferation-related phenotypes in this primary-cell model; however, they do not establish whether these effects are mediated by RA-dependent signaling.