Identification, cloning, and characterization of a novel human T-cell- specific tyrosine kinase located at the hematopoietin complex on chromosome 5q

Signal transduction through the T-cell receptor and cytokine receptors on the surface of T lymphocytes occurs largely via tyrosine phosphorylation of intracellular substrates. Because neither the T-cell receptor nor cytokine receptors contain intrinsic kinase domains, signal transduction is thought to occur via association of these receptors with intracellular protein tyrosine kinases. Although several members of the SRC and SYK families of tyrosine kinases have been implicated in signal transduction in lymphocytes, it seems likely that additional tyrosine kinases involved in signal transduction remain to be identified. To identify unique T-cell tyrosine kinases, we used polymerase chain reaction-based cloning with degenerate oligonucleotides directed at highly conserved motifs of tyrosine kinase domains. We have cloned the complete cDNA for a unique human tyrosine kinase that is expressed mainly in T lymphocytes (EMT) and natural killer (NK) cells. The cDNA of EMT predicts an open reading frame of 1866 bp encoding a protein with a predicted size of 72 Kd, which is in keeping with its size on Western blotting. A single 6.2-kb EMT mRNA and 72-Kd protein were detected in T lymphocytes and NK-like cell lines, but were not detected in other cell lineages. EMT contains both SH2 and SH3 domains, as do many other intracellular kinases. EMT does not contain the N-terminal myristylation site or the negative regulatory tyrosine phosphorylation site in its carboxyterminus that are found in the SRC family of tyrosine kinases. EMT is related to the B-cell progenitor kinase (BPK), which has recently been implicated in X-linked hypogammaglobulinemia, to the TECI mammalian kinase, which has been implicated in liver neoplasia, to the more widely expressed TECII mammalian kinase, and to the Drosophila melanogaster Dsrc28 kinase. Sequence comparison suggests that EMT is likely the human homologue of a recently identified murine interleukin-2 (IL-2)-inducible T cell kinase (ITK). However, unlike ITK, EMT message and protein levels do not vary markedly on stimulation of human IL-2-responsive T cells with IL-2. Taken together, it seems that EMT is a member of a new family of intracellular kinases that includes BPK, TECI, and TECII. EMT was localized to chromosome 5q31-32, a region that contains the genes for several growth factors and receptors as well as early activation genes, particularly those involved in the hematopoietic system. Furthermore, the 5q31-32 region is implicated in the genesis of the 5q- syndrome associated with myelodysplasia and development of leukemia.(ABSTRACT TRUNCATED AT 400 WORDS)     

Alteration of Polymeric Immunoglobulin Receptor and Neonatal Fc Receptor Expression in the Gut Mucosa of Immunodeficiency Virus‐Infected Rhesus Macaques

Polymeric immunoglobulin receptors (pIgR) and neonatal Fc receptors (FcRn) are crucial immunoglobulin (Ig) receptors for the transcytosis of immunoglobulins, that is IgA, IgM and IgG, the levels of which in mucosal secretions were altered in both HIV‐ and SIV‐infected individuals. To gain an insight into the changes of pIgR and FcRn expression after immunodeficiency virus (SHIV/SIV) infection, real‐time RT‐PCR methods were established and the mRNA levels of pIgR and FcRn in normal and SHIV/SIV‐infected rhesus macaques were quantitatively examined. It was found that the levels of pIgR mRNA were within a range of 10⁷ copies per million copies of GAPDH mRNA in the gut mucosa of rhesus macaques, which were up to 55 times higher than that in the oral mucosa, the highest among the non‐gut tissues examined. Levels of FcRn mRNA were generally lower than that of pIgR, and the levels of FcRn mRNA in the gut mucosa were also lower than that in most non‐gut tissues examined. Notably, the levels of pIgR mRNA in the duodenal mucosa were positively correlated with that of IL‐17A in normal rhesus macaques. Both pIgR and FcRn mRNA levels were significantly reduced in the duodenal mucosa during acute SHIV infection and in the jejunum and caecum during chronic SHIV/SIV infection. These data expanded our knowledge on the expression of pIgR and FcRn in the gastrointestinal tract of rhesus macaques and demonstrated altered expression of pIgR and FcRn in SHIV/SIV, and by extension HIV infections, which might have contributed to HIV/AIDS pathogenesis.     

香椿皮与臭椿皮的体外抗菌作用比较

目的：观察香椿皮、臭椿皮的抗菌作用。方法：本文采用琼脂平板稀释法对香椿皮、臭椿皮的水提取物和醇提取物进行了体外抗菌试验对比研究。结果：香棒皮的水提取物对金黄色葡萄球菌、绿脓杆菌、大肠杆菌均有抑杀作用;而臭椿皮水提聚物对金黄色葡萄球菌只有微弱的抑杀作用。对绿脓杆菌、大肠杆菌无抑杀作用。结论：香椿皮、臭椿皮来源于两种不同科属的植物,抗菌效果不同,成分不同,不宜混用。