ISSN:
1432-1211
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Abstract We examined the possibility that one mechanism for controlling HLA-DR-α gene expression involves the alteration of chromatin structure. Chromatin structure was analyzed by measuring the susceptibility of DR α genes in intact nuclei to nuclease treatment. We first examined a somatic cell hybrid of a T-lymphoblastoid cell line (LCL) and a B-LCL, since the DR αgene, which is inactive in the T-LCL parent, is expressed in the hybrid, thus providing a system to study DR αgene induction. The hybrid line 174 × CEM.T1 contains and expresses solely the DR αgene from the T-LCL parent, since the DR αgene from the B-LCL parent, 174, is deleted. Using cytoplasmic dot blot analysis and RNA-DNA Northern hybridization, we detected DR α-specific transcripts in the hybrid, but not in the parental lines, indicating activation of the DR αgene in the hybrid. The transcribed DR αgene from the hybrid was compared with the untranscribed gene from the T-LCL parental line, and an association between DR αgene expression and increased sensitivity to DNase I was observed. A switch in the chromatin structure of the DR αgene from a closed to an open configuration apparently occurred in this hybrid. Such a change is associated with DR αgene expression. Comparison of a DR-positive B-LCL and an isogenic DR-negative T-LCL also showed that the chromatin of the former is more sensitive to DNase I digestion. There were no restriction enzyme fragment length differences between the DR αgenes from 174 × CEM.T1 and CEMR, indicating that the process of somatic cell hybridization did not result in DNA rearrangement or translocation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00430305
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