Signal transducer and activator of transcription 5 (STAT5), a key transcription factor, is activated in response to the various cytokines and hormones, including interleukin-2 (IL-2), IL-3, IL-5, IL-7, IL-9, IL-15, growth hormone, prolactin, erythropoietin, and, thrombopoietin (9630227, 10817963). Two paralogs, known as STAT5a and STAT5b, were widely studied in mammals, and showed their distinct cellular functions; STAT5a for Prl-mediated mammary gland development and STAT5b for sexually dimorphic growth (PMID: 11983158). Structurally, STAT5 protein shared common architectural domain organizations as other STAT members bearing N-terminal domain, coiled coil domain, DNA binding domain, linker domain, Src homology 2 (SH2) domain and transcriptional activation domain (PMID: 11983158).
In teleosts, limited studies have been reported in the characterization of STAT5 members. In pufferfish (Tetraodon fluviatilis), an ortholog of STAT5 was identified, and demonstrated its DNA-binding and transactivation potential towards fish promoter (12605675). Meanwhile, a STAT5 member was identified from mandarinfish (Siniperca chuatsi) and showed a functional role against poly I:C (19539032). In addition, two STAT5 orthologs were identified from zebrafish (Danio rerio) and structurally characterized (15302407).
Rock bream, Oplegnathus fasciatus, is a commercially important marine fish species due to it its high demand as a delicacy. Information regarding disease management will be essential to control the mortality of rock bream caused by various microbial pathogens and other stress factors (Check previous papers). In the present study, we have identified and characterized two variants of STAT5 from rock bream. To understand the functional aspects, temporal transcription profiles were analyzed in vivo upon stimulation with pathogen and pathogen-associated molecular patterns (PAMPs), and tissue injury.