Identification, expression pattern, and immune response of Tim‐1 and Tim‐4 in embryos and adult medaka (Oryzias latipes)

Abstract

T‐cell immunoglobulin (Ig) and mucin domain‐containing 1 (Tim‐1) and Tim‐4 are two members of the Tim family. In mammals, Tim‐1 and Tim‐4 are proteins mainly expressed in immune cells and are associated with immune response. In the present study, medaka Oryzias latipes' Tim‐1 (OlTim‐1) and OlTim‐4 were identified and characterized using bioinformatics analyses. With the use of reverse‐transcription polymerase chain reaction, the expression profiles of OlTim‐1 and OlTim‐4 were examined in embryos and adult fish and in immune tissues following the intraperitoneal injection of stimulants. The results revealed that OlTim‐1 possesses a cytoplasmic region, a transmembrane region, a mucin domain, and an Ig‐like domain, while OlTim‐4 is composed of two Ig‐like domains and a mucin domain, but without the transmembrane region and cytoplasmic region. OlTim‐1 and OlTim‐4 expressions are detectable from the gastrula stage on, indicating that they are zygotic genes. Furthermore, OlTim‐1 and OlTim‐4 are expressed ubiquitously in the adult. Administration of immune stimulants, namely lipopolysaccharides and polyinosinic:polycytidylic acid, significantly increased the expression levels of OlTim‐1 and OlTim‐4 in the liver and intestine within 1 day and in the head, kidney, and spleen within 3 to 4 days postinjection. These results suggest that OlTim‐1 and OlTim‐4 are possibly involved in both innate and adaptive immunities.