Transient recruitment of the hnRNP K protein to inducibly transcribed gene loci.
The heterogeneous nuclear ribonucleoprotein K protein is an RNA- and DNA-binding protein implicated in the regulation of multiple processes that comprise gene expression. We used chromatin immunoprecipitation (ChIP) assays to explore K protein interactions with serum-inducible, constitutively expressed and untranscribed gene loci in vivo. In the rat HTC-IR hepatoma cell line, serum treatment induced transient increases in the mRNA levels of two immediate-early genes, egr-1 and c-myc. ChIP analysis showed that the induction of egr-1 and c-myc genes was associated with a transient recruitment of K protein to multiple sites within each of these loci, including the promoter and transcribed regions. In contrast, recruitment of K protein to the constitutively transcribed beta-actin locus and to randomly chosen non-transcribed loci was far weaker. In rat mesangial cells, c-myc was constitutively expressed while egr-1 remained serum responsive. In these cells, ChIP analysis showed serum-induced recruitment to the inducible egr-1 but not to the c-myc locus. Pre-treatment with the transcription inhibitor actinomycin D blocked the inducible but not the constitutive binding of K protein to these loci. Taken together, the results of this study suggest that the transient recruitment of K protein to serum-responsive loci depends on the inducible transcription of these immediate-early genes.
Ostrowski
Jerzy
J
Department of Medicine, University of Washington, Seattle, WA 98195, USA.
Kawata
Yasunobu
Y
Schullery
Daniel S
DS
Denisenko
Oleg N
ON
Bomsztyk
Karol
K
D000818:Animals; D016895:Culture Media, Serum-Free / Q000494:pharmacology; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics; D051766:Early Growth Response Protein 1; D015870:Gene Expression; D034641:Heterogeneous-Nuclear Ribonucleoprotein K / Q000378:metabolism*; D017874:Immediate-Early Proteins / Q000235:genetics; D011233:Precipitin Tests / Q000379:methods; D011485:Protein Binding; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000235:genetics; D014158:Transcription, Genetic / Q000187:drug effects / Q000235:genetics*; D014407:Tumor Cells, Cultured
D016895:Culture Media, Serum-Free; D004268:DNA-Binding Proteins; D051766:Early Growth Response Protein 1; C486110:Egr1 protein, rat; D034641:Heterogeneous-Nuclear Ribonucleoprotein K; D017874:Immediate-Early Proteins; D016271:Proto-Oncogene Proteins c-myc; D012333:RNA, Messenger; D014157:Transcription Factors; D004247:DNA