Molecular identification of suppressor of cytokine signaling 2 (SOCS2) and its response to BmNPV in Bombyx mori (Lepidoptera: Bombycidae)

Abstract

The suppressor of cytokine signaling 2 (SOCS2), an essential member of the SOCS family, is a classic negative regulator of the JAK-STAT-IFN signaling pathway. Current research focuses on mammalian systems, particularly in humans, with comparatively less emphasis on invertebrate models. We discovered two unique isoforms of SOCS2 in Lepidoptera, such as Bombyx mori, named SOCS2S and SOCS2L, respectively. The protein sequences of the two isoforms differ only in the N-terminal region. SOCS2 expression profiles in Bombyx mori are highest during the embryo or the first larval instar stage, decreasing from the second to the fourth larval instar stage and reaching the lowest point during the fifth larval instar stage. Its expression is up-regulated during metamorphosis development stages, indicating that they mainly play roles in embryonic development and metamorphosis. An exception is observed in the expression level of SOCS2L in silkworm strain 306, which does not show a downward trend during the larval stage. The response modes of two SOCS2 proteins to Bombyx mori nucleopolyhedrovirus (BmNPV) are different, with SOCS2S showing a more intense response. Subcellular localization shows that they exist in the cytoplasm. The study provides a foundation for further study on the function of SOCS2 in silkworms.