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 (<i>IGF1R</i>) gene in <i>Alopex lagopus</i> (Arctic fox), thereby addressing the existing knowledge gap regarding <i>IGF1R</i>-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 <i>IGF1R</i> gene (Accession No. XM_545828). The full-length coding sequence (CDS) of the Arctic fox <i>IGF1R</i> 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 <i>IGF1R</i> gene between the Arctic fox and canine, confirmed their closest evolutionary relationship. Protein characterization showed that the <i>IGF1R</i> 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 α-helices (26.39%) and random coils (52.79%). The <i>IGF1R</i> 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 <i>IGF1R</i> 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 <i>IGF1R</i> may participate in metabolism and organ developmental processes during critical growth stages of Arctic foxes through tissue-specific regulation.