Cathepsin L gene: Molecular characterization, functional analysis and expression profile in the endometrium of goat (Capra hircus)

In ruminant species, endometrial remodeling plays a pivotal role in regulation of estrous cycle and establishment of pregnancy. Among interferon tau (IFNT) stimulated genes, cathepsin (CTS) L is one of them, which is up-regulated in the endometrium during early pregnancy and plays an important role in endometrial remodeling and embryo development. However, the specific role of CTSL is not yet documented in goats. Therefore, in the present study, coding sequence (CDS) of CTSL was cloned, characterized, and its temporal expression profile was also examined in the endometrium of caprine (cp) for the first time. A fragment of cpCTSL, 963 bp in length, was amplified from complementary DNA (cDNA) with a 936 bp coding sequence, which encodes a polypeptide of 312 amino acids. Coding and deduced amino acid sequences of cpCTSL exhibited 72.8 to 99.3% identities with other species. A polypeptide of 312 amino acids of cpCTSL revealed three domains, a signal peptide sequence, a pro-domain and a partially mature domain. Further, the relative expression of cpCTSL mRNA and protein was determined by quantitative real-time PCR and western blot, respectively, in the endometrium of pregnant and cyclic does. Both cpCTSL mRNA and protein were expressed maximally (P < 0.05) during early pregnancy and these were 11.34 and 5.48-fold greater (P < 0.05), respectively, as compared to cyclic does. It is concluded that CTSL is mostly similar in structure to other species and increased level in the endometrium indicates its involvement in endometrial remodeling to sustain pregnancy in goats.