Molecular characterization of two suppressor of cytokine signaling 1 genes (SOCS1a and SOCS1b) in chickens

Abstract

Suppressor of cytokine signaling 1 (SOCS1) protein can inhibit the signal transduction triggered by some cytokines or hormones and thus are important in many physiological/pathological processes, including innate and adaptive immunity, inflammation, and development in mammals. However, there is sparse information about their structure, tissue expression, in birds, where their biological functions remain unknown. In this study, we cloned and characterized two SOCS1 genes (named cSOCS1a and cSOCS1b) from chickens. SOCS1a is predicted to encode a 207-amino acid protein, which shares high amino acid sequence identity (64%-67%) with human and mouse SOCS1. Besides SOCS1a, a novel SOCS1b gene was also identified in chickens and other non-mammalian vertebrates including Xenopus tropicalis. Chicken SOCS1b is predicted to encode a 212-amino acid protein, which shares only 30%-32% amino acid sequence identity with human SOCS1 and cSOCS1a. RT-PCR assay revealed that both cSOCS1a and cSOCS1b are widely expressed in all chicken tissues. Using a luciferase reporter assay system, we further demonstrated that transient expression of cSOCS1a and cSOCS1b can significantly inhibit chicken growth hormone (GH)-or prolactin (PRL)-induced luciferase activities of Hep G2 cells expressing cGH receptor (or cPRL receptor), indicating that SOCS1a and SOCS1b proteins can negatively regulate GH/PRL signaling. Taken together, these data suggest that both cSOCS1a and cSOCS1b may function as negative regulators of cytokine/hormone actions, such as modulation of GH/PRL actions in chickens.