Mechanism for decrease of glucocorticoid receptor mRNA in human hepatic cancer cell line SMMC-7721 during heat shock

Abstract

Objective:To investigate the mechanism for decrease of glucocorticoid receptor mRNA(GR mRNA)during heat shock response.Methods:The changes of GR mRNA level in SMMC-7721 cells were examined by semi-quantitative RT-PCR during heat shock response.We designed 2 RNA fragments paired with GR gene intron E and cross exon 3,4,and 5,which were used as probes for in situ hybridization with the sequences in SMMC-7721 cells at different periods after heat shock.The result was subjected to confocol microscope observation and computer image analysis.The transcription,degradation,and splicing of GR mRNA were investigated.Results:RT-PCR showed that the GR mRNA level was decreased during heat shock response.In situ hybridization revealed that both GR mRNA and GR pre-mRNA levels were lower in the heat shock group than in the non-heat shock group(P0.05).GR pre-mRNA level was higher in cells treated with actinomycine D before heat shock than in cells only treated with actinomycine D,while the GR mRNA level was lower in cells treated with actinomycine D before heat shock(P0.05).Conclusion:During heat shock response,GR mRNA transcription is suppressed,the splicing of GR pre-mRNA is suppressed,and GR mRNA degradation is accelerated.