《Nature》：猴子为何可以抵抗HIV
http://www.100md.com
2004年7月29日
“旧世界”猴子能抵抗SIV(猴免疫缺陷病毒)和HIV(人免疫缺陷病毒)的感染，原因是由于衣壳特定的制约因子。这种先天抵抗力由TRIM5α调节，它是胞质体的一个蛋白成分。在多数“新世界”猴子中，HIV在进入细胞后就不受制约。猫头鹰猴是例外，这种猴子阻挡HIV-1病毒的屏障是由衣壳突变体或破坏衣壳与 cyclophilin A (CypA)相互作用的药物释放的。对这种矛盾现象所做的一项研究表明，通过RNA干涉剔除猫头鹰猴的CypA，可抑制其抗HIV-1活性，但再引入CypA蛋白却不能恢复抗病毒活性。研究人员还发现了另一个RNAi目标，即一个RNA信使，它为一个TRIM5-CypA融合蛋白编码。TRIMCyp能解释HIV-1病毒进入猫头鹰猴体内后为什么会受到制约，当转移进人类细胞后它会阻止HIV-1病毒感染。TRIMCyp基因似乎是在“新世界”和“旧世界”灵长类分化后出现的，当时在一个逆转录转位子(“跳跃基因”)的催化下，CypA基因插进了TRIM5基因的位点。
Cyclophilin A retrotransposition into TRIM5 explains owl monkey resistance to HIV-1
, 百拇医药
In Old World primates, TRIM5-
confers a potent block to human immunodeficiency virus type 1 (HIV-1) infection that acts after virus entry into cells. Cyclophilin A (CypA) binding to viral capsid protects HIV-1 from a similar activity in human cells. Among New World primates, only owl monkeys exhibit post-entry restriction of HIV-1 (ref. 1). Paradoxically, the barrier to HIV-1 in owl monkey cells is released by capsid mutants or drugs that disrupt capsid interaction with CypA. Here we show that knockdown of owl monkey CypA by RNA interference (RNAi) correlates with suppression of anti-HIV-1 activity. However, reintroduction of CypA protein to RNAi-treated cells did not restore antiviral activity. A search for additional RNAi targets unearthed TRIMCyp, an RNAi-responsive messenger RNA encoding a TRIM5–CypA fusion protein. TRIMCyp accounts for post-entry restriction of HIV-1 in owl monkeys and blocks HIV-1 infection when transferred to otherwise infectable human or rat cells. It seems that TRIMCyp arose after the divergence of New and Old World primates when a LINE-1 retrotransposon catalysed the insertion of a CypA complementary DNA into the TRIM5 locus. This is the first vertebrate example of a chimaeric gene generated by this mechanism of exon shuffling.
, 百拇医药
Figure 2 Owl monkey cells express a TRIM5–CypA fusion protein that blocks HIV-1 infection. a, Predicted amino-acid sequence of 54-kD TRIMCyp protein. TRIM5 segment highlighted in grey with domains indicated above; CypA segment highlighted in black. b, Immunoblot of 293T cells transfected with TRIMCyp expression vector, probed for TRIM5 and CypA. c, d, RT–PCR for TRIMCyp, CypA or TRIM5-
in OMK, human HeLa and Jurkat, and macaque FRhK4 cells (c), and PBMC from two Aotus nancymaae monkeys (d). e, Amplification plot of real time RT–PCR. The green curves show undiluted and threefold serial dilutions of OMKMH-Luc cDNA; the black curve is undiluted OMKMH-CypA-147 cDNA; the yellow curves are 'no RT' controls. Rn, normalized reporter signal, R2, the correlation coefficient for the diluted samples. GAPDH amplification curves (not shown) were identical between samples. f, OMKMH-CypA-147 cells transduced with the indicated RNAi-resistant cDNAs and infected with HIV-1.
, http://www.100md.com
Figure 4 TRIMCyp arose from retrotransposition of CypA cDNA into TRIM5. a, Part of the owl monkey TRIM5 locus showing a complete, processed CypA cDNA inserted after exon 7. b, c, TRIM5 genomic sequence flanking the 5' end (b) or the 3' end (c) of the CypA insertion aligned with homologous human sequence. TRIMCyp exons and the region homologous to human exon 8 are in capital letters, introns in lower case, and the CypA cDNA insertion highlighted in grey. The 'natural' CypA start codon, the CypA/TRIMCyp poly-adenylation signal and poly-A tail are underlined. The insertion is flanked by a 16-bp target site duplication (TSD), highlighted in black. At, Aotus trivirgatus. Hs, Homo sapiens.
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Cyclophilin A retrotransposition into TRIM5 explains owl monkey resistance to HIV-1
, 百拇医药
In Old World primates, TRIM5-
confers a potent block to human immunodeficiency virus type 1 (HIV-1) infection that acts after virus entry into cells. Cyclophilin A (CypA) binding to viral capsid protects HIV-1 from a similar activity in human cells. Among New World primates, only owl monkeys exhibit post-entry restriction of HIV-1 (ref. 1). Paradoxically, the barrier to HIV-1 in owl monkey cells is released by capsid mutants or drugs that disrupt capsid interaction with CypA. Here we show that knockdown of owl monkey CypA by RNA interference (RNAi) correlates with suppression of anti-HIV-1 activity. However, reintroduction of CypA protein to RNAi-treated cells did not restore antiviral activity. A search for additional RNAi targets unearthed TRIMCyp, an RNAi-responsive messenger RNA encoding a TRIM5–CypA fusion protein. TRIMCyp accounts for post-entry restriction of HIV-1 in owl monkeys and blocks HIV-1 infection when transferred to otherwise infectable human or rat cells. It seems that TRIMCyp arose after the divergence of New and Old World primates when a LINE-1 retrotransposon catalysed the insertion of a CypA complementary DNA into the TRIM5 locus. This is the first vertebrate example of a chimaeric gene generated by this mechanism of exon shuffling., 百拇医药
Figure 2 Owl monkey cells express a TRIM5–CypA fusion protein that blocks HIV-1 infection. a, Predicted amino-acid sequence of 54-kD TRIMCyp protein. TRIM5 segment highlighted in grey with domains indicated above; CypA segment highlighted in black. b, Immunoblot of 293T cells transfected with TRIMCyp expression vector, probed for TRIM5 and CypA. c, d, RT–PCR for TRIMCyp, CypA or TRIM5-
in OMK, human HeLa and Jurkat, and macaque FRhK4 cells (c), and PBMC from two Aotus nancymaae monkeys (d). e, Amplification plot of real time RT–PCR. The green curves show undiluted and threefold serial dilutions of OMKMH-Luc cDNA; the black curve is undiluted OMKMH-CypA-147 cDNA; the yellow curves are 'no RT' controls. Rn, normalized reporter signal, R2, the correlation coefficient for the diluted samples. GAPDH amplification curves (not shown) were identical between samples. f, OMKMH-CypA-147 cells transduced with the indicated RNAi-resistant cDNAs and infected with HIV-1., http://www.100md.com
Figure 4 TRIMCyp arose from retrotransposition of CypA cDNA into TRIM5. a, Part of the owl monkey TRIM5 locus showing a complete, processed CypA cDNA inserted after exon 7. b, c, TRIM5 genomic sequence flanking the 5' end (b) or the 3' end (c) of the CypA insertion aligned with homologous human sequence. TRIMCyp exons and the region homologous to human exon 8 are in capital letters, introns in lower case, and the CypA cDNA insertion highlighted in grey. The 'natural' CypA start codon, the CypA/TRIMCyp poly-adenylation signal and poly-A tail are underlined. The insertion is flanked by a 16-bp target site duplication (TSD), highlighted in black. At, Aotus trivirgatus. Hs, Homo sapiens.
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