International Mammalian Genome Society

The 13th International Mouse Genome Conference
October 31-November 3, 1999

Table of Contents * Structure * Bioinformatics * Sequence * Mapping * New Tools * Gene Discovery * Developmental * Mutagenesis * Functional Genomics

E37 Dysfunctional Intestine and Abnormality in CNS Found in XPG-Deficient Mice

Yoshi-nobu Harada1, Xue-Zhi Sun2, Atsushi Tsuji3, Naoko Shiomi1, Tadahiro Shiomi1. 1The Genome Research Group, National Institute of Radiological Sciences, Anagawa, Inage-ku, Chiba 261-8555 Japan.; 2The 4th Research Group, National Institute of Radiological Sciences; 3Institute for Experimental Animals, Hamamatsu University School of Medicine, 3600 Handa-cho, Hamamatsu 431-3192, Japan

The xeroderma pigmentosum group G (XP-G) gene (XPG) encodes a structure-specific DNA endonuclease that functions in nucleotide excision repair (NER). XP-G patients show various symptoms, ranging from mild cutaneous abnormalities to severe dermatological impairments. In some cases, patients exhibit growth failure and life-shortening and neurological dysfunctions, which are characteristics of Cockayne syndrome (CS). The known XPG protein function as the 3' nuclease in NER, however, cannot explain complexed chrinical phenotype associated with XPG. To investigate an additional function(s) besides its role in NER, we have generated a gene disrupted XPG model mouse strain, XPG/2.

As we had reported at the 12th IMGC meeting, the growth of XPG/2 mutant homozygotes was severely inhibited and they died before weaning. Then we carried out histological analysis on several organs of the XPG/2 mice at various days. The average weight of brain from mutant homozygotes were about 80% of those from normal littermates. The number of cells expressing parvalbumin in non-pyramidal cells has been reduced in mutant homozugotes at 16 days. This fact suggests that disruption of mouse Xpg gene affects the development of central nervous system of mice. The small intestine of the mutant homozygotes were apparently smaller in diameter than those of wild-type mice. The number and size of villi were reduced on and after day 5. At 16 and 21 days, the stomach and the intestines in the mutant homozugotes mice were relatively small, and many gas bubbles were present inside the intestine, suggesting dysfunction of the intestine. The concentrations of glucose and triglyceride in serum of mutant homozygotes were extremely lower than those of wild-type. These evidences suggest that mouse Xpg gene is essential for the development of the small intestine and/or the ingestion of nutrition at the small intestine. Although such abnormality of the small intestine and the accompanying intestinal dysfunction have not been reported in XPG/CS complex patients, we believe that XPG/2 strain is a good model to study the functions of XPG gene.


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