兰州大学机构库 >生命科学学院
CD72和SNX21的选择性剪切现象研究
Alternative TitleThe study of alternative splicing phenomenon of CD72 and SNX21
朱洁滢
Thesis Advisor吉尚戎
2007-04-05
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name博士
Keyword选择性剪切 CD72 B细胞受体 系统性红斑狼疮 NZB/W 小鼠 SNX21 内涵体 EGFR MT1-MMP
Abstract

本论文分别研究了CD72和SNX21两种基因的选择性剪切现象。CD72是一个重要的 B 细胞特异性受体,它以多种选择性剪切形式存在。本文在小鼠脾细胞中发现并鉴定了 8 种新的 CD72 选择性剪切形式,这些剪切形式中包含有两种独特的插入片断,一种选择性剪切保留了一个内含子(intron1),而这个内含子被翻译成氨基酸序列后并没有改变前后外显子的读码框;另一种使用了一个位于内含子之内的3’剪切位点,从而产生移码,提前终止了蛋白的开放读码框。本文称之为3’AS (3’ alternative splicing site)。本文比较了CD72所有剪切形式(共 12 种)在BALB/C小鼠和NZB/W小鼠中的差异表达,发现:1,含有 alternative 3’ss的剪切形式的表达都很少;2,WT,+In1,+In1-Ex3和-Ex3 的表达在 BLAB/C 小鼠中比在 NZB/W 小鼠中高;3,没有穿膜区和 ITIM2 的-Ex2-Ex3剪切形式在 NZB/W 小鼠中有特异性高表达。这些结果显示,CD72 的多种选择性剪切形式在介导 BCR 信号过程中发挥着不同的作用,与系统性红斑狼疮的发病密切相关。SNX21 是分选蛋白(Sorting NeXin)家族的一个较新的成员,本文在克隆中发现并鉴定了它的一个新的选择性剪切形式(本文称之为 SNX21S),比报道中的 SNX21 基因(本文称之为 SNX21L)少了 74 个氨基酸,其中包括了一个“出核信号”。为了研究它们的功能本文建立了它和 SNX21L 以及它们俩的 R147A 突变体在肿瘤细胞中的稳定转染细胞株。通过对这些
稳定转染细胞株的研究,本文发现:1) SNX21S 主要定位于核内, SNX21L 则主要定位于胞质内;2)SNX21 的两种形式都可定位于内涵体的膜上,并使内涵体小泡增大增多,而它们的突变体则没有这样的定位和作用;3),除 SNX21S 的突变体外,其他几种 SNX21都可抑止 EGFR在饥饿后的细胞中聚集于膜上,并抑止 EGFR 在 EGF 刺激后的降解; 4),SNX21S 及其突变体可明显抑止 MT1-MMP 的活性,SNX21 的两种突变体(SNX21Lm和SNX21Sm)可明显促进ΔC-MMP的活性,两种野生型(SNX21L和SNX21S)则可抑止ΔC-MMP的活性;5),SNX21L可明显促进肿瘤细胞的增殖,并且使肿瘤细胞的增殖对血清的依赖性明显下降。

Other Abstract

CD72 is a B cell specific receptor that exists in multiple alternative splicing forms.We identified eight novel alternative splicing forms of CD72 from the spleenocytes of Balb/C mice.Two very unique intron sequences were found in those
alternative splicing forms.One kind of splicing variants retained the intron1 in the mRNA.This intron can be translated into 32 amino acid residues without changing the reading frame of the whole proteins. Another kind of splicing variants used an alternative 3’splice site in intron 3 (3’AS) which led to premature termination of its encoded protein.We compared the differential expression of the CD72 splicing variants in Balb/C and NZB/W mice that were at different stage of SLE disease development.We found that 1)splicing forms containing 3’AS was rare in all samples examinated;2)splicing forms containing two ITIM domains and transmembrane domains were more abundant in Bab/C mice than in NZB/W mice,even in some cases the two ITIM domains were separated by the intron 1;3) a shorter splicing form with both exon2 and exon3 missing was expressed highly in terminally diseased NZB/W mice.These results suggested an important role of CD72 alternative splicing forms in B cell receptor signaling and in SLE.SNX21 is a new member of the SNX (Sorting NeXin) family.We have found and identifited a new alternative splicing form of SNX21. We cold it SNX21S,which is shorter than the SNX21L,the SNX21 which be reported before.The absent domain have 74 amino acid, including a extra-nuclear fignal.We founded 5 kind of stableline of SNX21S and SNX21L,and the two mutantions (R147A) of them to study the function of SNX21.We find: 1).The position of SNX21S is in the nuclear,whereas the position of SNX21L is in the cytoplasm;2).The position of SNX21S&L are both in the membrane of endosome,whereas the two mutations of them without this characteristic;3).These forms of SNX21 all can decrease the collect of EGFR on the cell membrane and decreace the degradation of EGFR after the stimulation by EGF, except the mutantion of SNX21S;4).SNX21S and the mutation of it can decrease the activition of the MT1-MMP obviously.The two mutations can increase the activition of ΔC-MMP, whereas the two widetype of SNX21 have the contrary effect;5).SNX21L can increase the proliferation of tumour cell line evidently, and decrease the dependent of serum of the tumour cell line.

URL查看原文
Language中文
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/222039
Collection生命科学学院
Recommended Citation
GB/T 7714
朱洁滢. CD72和SNX21的选择性剪切现象研究[D]. 兰州. 兰州大学,2007.
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