Disregulation of the RET proto-oncogene transcription may play a role in both inherited cancer syndromes and Hirschsprung disease. Understanding the gene regulation might provide new clues to clarify pathogenesis. Recently, we reported that RET transcription is highly cell-line specific, while the promoter region is equally active in different cell-lines. Here we show that RET upstream sequences can modulate gene expression via cell-line specific chromatin acetylation level contributing to promoter function. Acetylation and deacetylation activities, working on specific lysines of histonic tails, alter the accessibility of transcription factors to DNA thus modulating gene expression. Histone deacetylase inhibitors, such as sodium butyrate, up regulate both RET mRNA levels and transcription rate in a RET expressing cell-line. The same treatment allows transcript detection in RET negative cell lines (lymphoblasts), while no enhancement is seen in cells expressing RET already at high level. Sensitivity to sodium butyrate appears to be sequence specific in transient transfection assays. Chromatin immunoprecipitation experiments, using antibody against H4 tetra-acetylated hystones, confirm the direct role of histone acetylation level within RET upstream region, in regulating gene expression. Sodium butyrate derepressive effect allowed us to overcome the lack of this gene expression in the majority of adult cells and analyse RET mRNA from Hirschsprung patients, by treating lymphoblastoid cell lines. Anomalous transcripts, defective gene expression, as well as nucleotide substitutions in the coding region were detected.

RET upstream sequences modulate gene expression via cell-line specific chromatin acetylation

FANELLI, MIRCO;
2002

Abstract

Disregulation of the RET proto-oncogene transcription may play a role in both inherited cancer syndromes and Hirschsprung disease. Understanding the gene regulation might provide new clues to clarify pathogenesis. Recently, we reported that RET transcription is highly cell-line specific, while the promoter region is equally active in different cell-lines. Here we show that RET upstream sequences can modulate gene expression via cell-line specific chromatin acetylation level contributing to promoter function. Acetylation and deacetylation activities, working on specific lysines of histonic tails, alter the accessibility of transcription factors to DNA thus modulating gene expression. Histone deacetylase inhibitors, such as sodium butyrate, up regulate both RET mRNA levels and transcription rate in a RET expressing cell-line. The same treatment allows transcript detection in RET negative cell lines (lymphoblasts), while no enhancement is seen in cells expressing RET already at high level. Sensitivity to sodium butyrate appears to be sequence specific in transient transfection assays. Chromatin immunoprecipitation experiments, using antibody against H4 tetra-acetylated hystones, confirm the direct role of histone acetylation level within RET upstream region, in regulating gene expression. Sodium butyrate derepressive effect allowed us to overcome the lack of this gene expression in the majority of adult cells and analyse RET mRNA from Hirschsprung patients, by treating lymphoblastoid cell lines. Anomalous transcripts, defective gene expression, as well as nucleotide substitutions in the coding region were detected.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11576/2520574
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