生物谷報導:美國明尼蘇達州的科研人員報導說,睡美人tranposon(Sleeping Beauty tranposon,SB-Tn)系統——一種能夠避免病毒轉移基因技術缺陷的基因治療技術,在實驗室中能夠矯正導致鐮狀細胞貧血病(SCD)的基因缺陷。
在這項發表在6月12日的ACS' Biochemistry的研究中,Clifford J. Steer和同事指出,病毒作為傳遞載體引發了多種安全關注。
在SCD中,編碼β-球蛋白的基因的一種突變導致血色素異常,使紅細胞變成鐮刀形。由於對病毒載體的潛在風險和其他問題的逐漸關注,使病毒載體用於基因治療遇到越來越多的障礙。
利用實驗室培養的細胞,研究人員證實SB-Tn系統可以將正常的β-球蛋白基因傳遞到細胞中。這個系統是一種魚基因,該基因在沉睡了1500萬年後於1997年被其他研究人員再次喚醒。該轉座子系統能夠滿足基因治療的關鍵要求。
細胞攝入由SB-Tn技術傳遞的基因,然後這些基因以長期穩定的狀態製造正常的β球蛋白。而且,這些基因能夠被遺傳,隨著細胞增殖而傳遞下去。
研究人員之所以將這種「睡美人」定義成一個轉座子或跳躍基因,是因為它能夠從一段DNA上的一個位置跳躍到另外的位置。
原始出處:
Biochemistry, 46 (23), 6844 -6858,
Web Release Date: May 18, 2007 Copyright © 2007 American Chemical Society
Erythroid-Specific Expression of -Globin by the Sleeping Beauty Transposon for Sickle Cell Disease
Jianhui Zhu, Betsy T. Kren, Chang Won Park, Rasim Bilgim, Phillip Y.-P. Wong, and Clifford J. Steer*
Department of Medicine and Department of Genetics, Cell Biology, and Development, University of Minnesota Medical School, Minneapolis, Minnesota 55455
Received November 28, 2006
Revised Manuscript Received February 22, 2007
Abstract:
Sickle cell disease (SCD) results predominately from a single monogenic mutation that affects thousands of individuals worldwide. Gene therapy approaches have focused on using viral vectors to transfer wild-type - or -globin transgenes into hematopoietic stem cells for long-term expression of the recombinant globins. In this study, we investigated the use of a novel nonviral vector system, the Sleeping Beauty (SB) transposon (Tn) to insert a wild-type -globin expression cassette into the human genome for sustained expression of -globin. We initially constructed a -globin expression vector composed of the hybrid cytomegalovirus (CMV) enhancer chicken -actin promoter (CAGGS) and full-length -globin cDNA, as well as truncated forms lacking either the 3' or 3' and 5' untranslated regions (UTRs), to optimize expression of -globin. -Globin with its 5' UTR was efficiently expressed from its cDNA in K-562 cells induced with hemin. However, expression was constitutive and not erythroid-specific. We then constructed cis SB-Tn--globin plasmids using a minimal -globin gene driven by hybrid promoter IHK (human ALAS2 intron 8 erythroid-specific enhancer, HS40 core element from human LCR, ankyrin-1 promoter), IHp (human ALAS2 intron 8 erythroid-specific enhancer, HS40 core element from human LCR, -globin promoter), or HS3p (HS3 core element from human LCR, -globin promoter) to establish erythroid-specific expression of -globin. Stable genomic insertion of the minimal gene and expression of the -globin transgene for >5 months at a level comparable to that of the endogenous -globin gene were achieved using a SB-Tn -globin cis construct. Interestingly, erythroid-specific expression of -globin driven by IHK was regulated primarily at the translational level, in contrast to post-transcriptional regulation in non-erythroid cells. The SB-Tn system is a promising nonviral vector for efficient genomic insertion conferring stable, persistent erythroid-specific expression of -globin.
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