| Part I, Expression pattern and functional study of a novel type I cytokine receptor CRL2 cloned from human dendritic cellsDendritic cells are the most potent antigen-presenting cells in human immune system. By large-scared random sequencing, we isolated a lot of novel full-length cDNAs from the cDNA library of human dendritic cells. In addition, we also constructed a cDNA library of bone marrow stromal cells (BMSC) and then isolated several novel full-length cDNAs. In the present study, we identified or investigated the biological functions of two novel molecules, one from DC and another one from BMSC.Novel type I cytokine receptor CRL2 was firstly cloned from DC cDNA library by us (BBRC, 2001). Several months later, scientists from DNAX research institute demonstrated that TSLP (Thymic Stromal Lymphopoietin) is a cytokine and its receptor cloned as hTSLPR. By doing homology search and comparing hTSLPR with CRL2, we found hTSLPR is the CRL2. The scientists from DNAX research institute did a lot of work on TSLP and found a lot of interesting phenomenon: human TLSP functions mainly on myeloid cells, human TLSP enhances the maturation of CD11c+ DC and maintains their survival. TSLP-activated DC mediate both CD4+ and CD8+ T cell responses with a proallergic phenotype. Mice overexpressing TSLP develop mixed cryoglobulinemia with renal disease closely resembling human cryoglobulin-associated membrano proliferative glomerulonephritis (MPGN), including glomerular deposits of immunoglobulins and complement. All of above results indicate that TSLP is a cytokine with multiple functionsand plays an important role the biological processes.In the paper published in BBRC, we identified a novel type I cytokine receptor, designated as CRL2 which consisted of 1579bp in length. The sequence predicted a type I transmembrane protein with a hydrophobic signal peptide of 22 amino acids and a singe transmembrane domain of 20 amino acids. The CRL2 mature protein comprised 349 amino acids. The CRL2 contained 2 conserved cysteine residues, and the sequence of PSDWS. The intracellular domain contained a membrane-proximal "box 1". Northern blot analysis revealed that an approximately 4.5-kb transcript of CRL2 was restrictedly expressed in spleen and peripheral blood leukocytes, and undetectable in most of the normal tissues, including thymus, liver, kidney, heart, skeletal muscle, brain, small intestine, placenta, lung, and colon tissue. CRL2 was preferentially expressed by DC and monocytes. Up-regulation of CRL2 expression was observed in peripheral monocytes and THP-1 cells after stimulation with PMA or LPS.In this work, we further investigated the expression pattern of CRL2 and functions of CRL2. We went further to analyze the CRL2 expression by various cells or cell lines under activation status. Up-regulation of CRL2 expression was observed in monocyte-derived DC after stimulation with LPS or agonistic anti-CD antibody. Up-regulation of expression was also observed in monocytes after stimulation with LPS. The CRL2 expression remained unchanged THP-1 cells after stimulated with TNF-a, CpG ODN , H2O2 and NO. In several kinds of cells, for example, BMSCs, Jurkatand NK92, CRL2 expression was inducible. CRL2 expression was detected in solid tumor cells including A549, SMMC7721, HeLa, LoVo, PC-3, MCF-7, A172, U251, Cao V, Skov 3.As described, the functional hTSLP receptor consists of two subunits: TSLPR(CRL2) and its heterodimerizated receptor IL-7R. Both receptor subunits are primarily expressed by DC. We found they are mainly expressed in peripheral blood leukocytes, DC and monocytes. Interestingly, both receptors were obviously up-regulated in DC and monocytes after LPS stimulation. These results indicate that CRL2 (TSLPR) may be involved in the biological functions of DC and moncytes. In addition, IL-7R expression was also detected in tumor cells HeLa, A172 and CaoV.LPS can initiate strong inflammatory responses that can eventually cause a fatal sepsis syndrome. The signaling pathway of LPS-mediated activation res...
|
PDF Full Text Request