マウスリンパ組織のレプチンレセプター発現細胞の検出

Abstract

Leptin, the product of the ob gene expressed in adipocytes, is shown to influence energy intake and expenditure, proliferation of CD^<4+> T cells, neovascularization and intracellular triglycerides homeostasis in non-adipocytes. Leptin acts on target cells through receptor (OB-R). There are at least five different types of OB-R in mouse due to alternative splicing from db gene transcripts.OB-Ra〜OB-Rd share identical extracellular and transmembrane domains and JAK binding consensus sequence at cytoplasmic domain. Only OB-Rb has an additional STAT binding motif and is essential for most of leptin' s physiological functions through JAK-STAT pathway. OB-Ra is also reported to transduct weakly leptin's signal through JAK-phospholyration pathway. On this paper we examined which kinds of cell express OB-Ra or OB-Rb in lymphoid and fat tissues of the mouse. Both types of OB-R were detected in thymus, spleen and gastrolienal fat tissue by RTPCR method, then the constitutive cells were separated from dissected tissues and cultured in GIT medium with 10% heat-inactivated FBS. Primary cultured lymphocytes isolated from thymus or spleen expressed both OB-Ra and OB-Rb. On the other hand, in adhesive cells dispersed with enzymatic digestion and primary cultured OB-Rb was not detected, though OB-Ra detectable.Similarly, primary cultured adhesive cells of gastrolienal fat tissue expressed only OB-Ra. It is therefore most parsimonious to conclude that only lymphocytes express OB-Rb and response effectively to leptin in thymus.