RECS1(responsive to centrifugal force and shear stress gene 1)是一血液剪切力应答蛋白.RECS1基因敲除的小鼠年老时易患主动脉囊性中层坏死并表现有大动脉扩张症,暗示RECS1可能参与调控血管的发育重塑.免疫组化分析发现,RECS1基因敲除(RECS1 knockout,RECS1 KO)的小鼠主动脉基质金属蛋白酶-9(matrix metalloproteinase-9,MMP-9)的表达水平明显提高,但RECS1的结构与功能及相关作用机理仍不清楚.研究发现,RECS1是肿瘤坏死因子受体2(tumor neucrosisfactor receptor 2,TNFR2)的结合蛋白质.报告基因检测实验表明,RECS1能特异地抑制TNFR2特异的激动性抗体或过量表达TNFR2诱导的核转录因子-κB(nuclear factor-κB,NF-κB)活化.NPLY模体缺失突变的RECS1不能结合TNFR2,并丧失对TNFR2介导NF-κB活化的抑制能力.稳定表达RECS1的MEFS细胞中,TNFR2特异的激动性抗体诱导的IκB(inhibitor of NF-κB)降解和NF-κB靶基因白介素-6(interleukin-6,IL-6)的表达均受到明显抑制.该研究揭示了RECS1通过与TNFR2的相互作用,负调控TNFR2介导肿瘤坏死因子信号传递的新功能及RECS1参与血管发育重塑调控的可能机制.
A full length cDNA encoding the growth hormone receptor (GHR) of Chinese sturgeon was cloned in order to investigate the mechanism of growth hormone in regulating the growth of Chinese sturgeon. The open reading frame of the cloned Chinese sturgeon growth hormone receptor (csGHR) cDNA encodes a trans-membrane protein of 611 amino acids containing all the characteristic motifs of GHR. By sequence alignment, substitutions of amino acid residues highly conserved in other species were identified. Using the CHO cell culture system, the function of csGHR and the biological significance of the amino acid substitution in csGHR were examined. The promoter of serine protease inhibitor 2.1 (Spi2.1) was trans-activated upon stimulation of seabream GH (sbGH) in the csGHR-expressing CHO cells. Furthermore, CHO cells stably expressing csGHR were stimulated to proliferate by sbGH. In agreement with our previous report, Chinese sturgeon growth hormone-binding protein (csGHBP) was detected in the culture medium of CHO cells stably expressing csGHR. Mutation of Asp residue in the ligand binding motif in csGHR to Glu significantly enhanced csGHR's biological function, whereas mutation of Asp residue to Ala decreased its biological function. The results demonstrated that the cloned csGHR was of full biological function and the csGHBP could be generated through proteolysis of csGHR. These findings might provide new insights into thoroughly understanding the regulatory mechanism of Chinese sturgeon growth.
LIAO ZhiYong1, CHEN XiaoLi2 & WU MingJiang1 1 College of Life and Environmental Science, Wenzhou University, Wenzhou 325035, China
