| Psoriasis is a common, chronic, inflammatory skin disorder. Histopathologically thedisease is characterized by hyperproliferation of the epidermis, accumulation of inflammatory cells and hyperplasia, elongation, dilatation and increased tortuosity of dermal papillary blood vessels. Owing to the unclear pathogenesis, psoriasis is the keystone in the study on the skin diseases. With the development of modern molecular biology, study on cell cycle progress rapidly. It has been shown that the CDK4-cyclinD kinase complex promotes progression entering the S of the cell cycle from GI phase. In normal cells, the retinoblastoma (Rb) tumor suppressor protein regulates cell proliferation by binding and sequestering transcription factors. Phosphorylated Rb, thereby allowing cells to enter S phase, releases these transcription factors at late Gl phase. The main function of the CDK4-cyclinD kinase complex may be to phosphorylate Rb at late GI phase. P16 protein coded by tumor suppressor gene p!6 has been characterized by specifically binding to and inhibiting CDK4/CDK6, and thus P16 protein may regulate phosphorylation of Rb, thereby p!6 gene may play an important role in the negative regulation of cell proliferation, microsatellites (MS) are simple tandemly repeated DNA sequence elements, found in greater or less abundance in the genomes of just about every known organism and organelle. Studies suggest that microsatellite instability (MSI) usually exist near the tumor suppressor gene loci. Tumor suppressor gene p!6, the CDK4 inhibitor, exist high frequency loss of heterozygosity (LOH) in many types of tumors cell line. However, a few literatures on microsatellite loss of heterozygosity in p!6 gene and pathogenesis of psoriasis have been reported presently in both domestic and foreign files. In order to investigate whether there are LOH in psoriatic lesions, to explore the relation between LOH in p!6 gene and pathogenesis in psoriasis and to get significant reference data for gene diagnosis and gene treatment of psoriasis, two microsatellite sites, D9sl71 located at the upstream of p!6 gene and D9sl604 located between exton 1 a and exton 13 were chosen to analyze the keratinocytes in psoriatic lesions and non-lesions.Materials and Methods23 progressive psoriasis patients, 14 male and 9 female, age from 12 to 67(44.09?.01), 13 with familial history and l0without familial history, 16 early onset and 7 late onset, 17 psoriasis vulgaris and 6 other types were chosen. Keratinocytes were cultured primarily from epidermis of the lesions and non-lesions undertaken respectively by the apparatus of epidermis transplanting for treating vitiligo, and genome DNA obtained by phenol extraction and ethanol precipitation following proteinase k digestion. The microsatellites were amplified by PCR, and the products of PCR were separated through denaturing polyacrylamide gel electrophoresis and visualized by silver staining.Results1. 10 and 5 out of 23 keratinocytes samples of psoriatic lesions exhibited LOH in D9sl604 and D9sl71, while in keratinocytes samples of psoriatic non-lesions the both sites were 3 and 2 cases respectively, no significant difference of the frequencies of LOH was noted between two sites (,P>0.05) , however, the LOH frequencies of the two microsatellite sites were closely correlated. The frequency of LOH was higher in keratinocytes samples of psoriatic lesions than in those of psoriatic non-lesions (P<0.05 ).2.The frequencies of LOH in D9sl604 and D9sl71 were 69.2%(9/13) and 30.8%(4/13) in keratinocytes samples with familial history of psoriatic lesions and 10.0%(1/10) and 10.0%(1/10) in those without familial history. Statistically, significant difference was demonstrated between samples with familial history and that without familial history frequencies of LOH samples with familial history were higher than those without familial history (P<0.05) .3.The frequencies of LOH in D9sl604and D9sl71 were 43.8% (7/16 ) and 18.8%(3/16) in keratinocytes samples of early onset psoriatic lesions 42...
|
PDF Full Text Request