Mutation Research, DNA Repair, 314 (1994) 11-19
© 1994 Elsevier Science Publishers B.V. All rights reserved 0921-8777/94/$07.00

11

MUTDNA 06565

Complementation of xeroderma pigmentosum cells by microinjection of mRNA fractionated under denaturing conditions: an estimation of sizes of XP-E and XP-G mRNA Yutaka Okuno, Satoshi Tateishi and Masaru Yamaizumi
Institute of Molecular Embryology and Genetics, Kumamoto University School of Medicine, Kuhonji 4-24-1, Kumamoto 862, Japan
(Received 19 February 1993) (Revision received 9 June 1993) (Accepted 10 June 1993)

Keywords: Xeroderma pigmentosum; Fractionation of mRNA; XP-E; XP-G; Microinjection assay

Summary
Excision repair deficiencies in groups A and G xeroderma pigmentosum (XP) cells are transiently complemented after microinjection of HeLa poly(A)+RNA, but those in groups D and F are not complemented (Legerski et al., 1984). We tested XP cells belonging to the seven complementation groups, A - G , and Cockayne's syndrome (CS) cells belonging to the two complementation groups, A and B, for transient correction by microinjection of total poly(A)+RNA from HeLa cells. Among the XP cells, unscheduled DNA synthesis (UDS) was increased only in XP-A ceils by microinjection of total poly(A)+RNA. However, UDS was increased in XP-E and XP-G cells as well as in XP-A cells by microinjection of concentrated poly(A)+RNA fractionated on a 5-25% sucrose density gradient containing methylmercuric hydroxide. The sizes of XP-E and XP-G mRNA were estimated to be 1.5-2.7 kb and 2.0-3.8 kb, respectively, by comparison to internal marker RNAs including 18S rRNA, 28S rRNA, HPRT mRNA and XPAC mRNA. RNA synthesis recovery after UV exposure in CS cells was not increased by microinjection of either total poly(A)+RNA or fractionated RNA. These results provide estimates of the sizes of XP-E and XP-G proteins and will facilitate molecular cloning of DNA repair genes, especially of XP-E and XP-G genes.

Xeroderma pigmentosum