Cloning and Spatiotemporal Expression Analysis of IGF1R Gene cDNA in Alopex lagopus (Arctic Fox)

This study aimed to clarify the sequence characteristics and spatiotemporal expression patterns of the insulin-like growth factor 1 receptor (IGF1R) gene in Alopex lagopus (Arctic fox), thereby addressing the existing knowledge gap regarding IGF1R-mediated growth regulation in this species. The findings establish a crucial foundation for subsequent investigations into the correlation between this gene and Arctic fox growth traits. Specific primers were designed based on the cDNA sequence of the canine IGF1R gene (Accession No. XM_545828). The full-length coding sequence (CDS) of the Arctic fox IGF1R gene (1617 bp, encoding 538 amino acids) was successfully cloned via RT-PCR. Phylogenetic analysis using the Unweighted Pair Group Method with Arithmetic Mean (UPGMA) algorithm revealed a 99% sequence homology in the IGF1R gene between the Arctic fox and canine, confirmed their closest evolutionary relationship. Protein characterization showed that the IGF1R protein has a molecular weight of 60.62 kDa (theoretical isoelectric point pI = 5.15), containing one fibronectin type-III domain and one tyrosine kinase domain, classifying it as an acidic hydrophilic transmembrane protein. Phosphorylation site prediction identified 27 phosphorylation sites, with secondary structures dominated by alpha-helices (26.39%) and random coils (52.79%). The IGF1R gene displayed significant tissue-specific expression variations across 12 examined tissues in Arctic foxes: highest expression levels in testis, minimal expression in stomach, and no detectable expression in duodenum. Spatiotemporal expression analysis revealed that in 2-, 4-, and 6-month-old individuals, hepatic IGF1R exhibited a progressive increase, testicular expression reached peak levels at 6 months, and skeletal muscle demonstrated transient upregulation peaking at 4 months. These spatiotemporal expression patterns suggest that IGF1R may participate in metabolism and organ developmental processes during critical growth stages of Arctic foxes through tissue-specific regulation.