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Induction of H3.3 replacement histone mRNAs during the precommitment period of murine erythroleukemia cell
D B Krimer1, G Cheng, A I Skoultchi
1Department of Cell Biology, Albert Einstein College of Medicine, Bronx, NY 10461.
Abstract:
Differential hybridization to a cDNA library made from the mRNA of differentiating mouse erythroleukemia (MEL) cells has been used to identify sequences that are induced during the early stages of MEL cell differentiation. One of the differentially expressed genes identified encodes the H3.3 histone subtype. We show here that the three polyadenylated mRNAs produced from the H3.3B gene, as well as the single mRNA produced from the related H3.3A gene, are coordinately induced during the first few hours of MEL cell differentiation and subsequently down regulated as cells undergo terminal differentiation. Nuclear run-on transcription experiments indicate that the accumulation and decay of these mRNAs are controlled at the post-transcriptional level. Unlike the polyadenylated mRNAs of two H1 histone genes that exhibit similar kinetics of induction and decay controlled by c-myc, induction of the H3.3 mRNAs is unaffected by deregulated expression of c-myc.
Insights
Researchers identified histone H3.3 gene expression during mouse erythroleukemia (MEL) cell differentiation. H3.3 mRNA levels are regulated post-transcriptionally and are independent of c-myc.
Area of Science:
- Molecular Biology
- Cell Biology
- Gene Regulation
Background:
- Mouse erythroleukemia (MEL) cells are a model system for studying cellular differentiation.
- Histone variants play crucial roles in chromatin structure and function during cellular processes.
- Understanding gene expression dynamics during differentiation is key to deciphering developmental pathways.
Purpose of the Study:
- To identify genes induced during early MEL cell differentiation.
- To characterize the expression patterns and regulation of the H3.3 histone subtype genes (H3.3A and H3.3B) during MEL cell differentiation.
Main Methods:
- Differential hybridization of a cDNA library from differentiating MEL cells.
- Analysis of mRNA levels for H3.3A and H3.3B genes.
- Nuclear run-on transcription assays.
- Investigation of c-myc's role in H3.3 mRNA regulation.
Main Results:
- The H3.3B and H3.3A genes are coordinately induced early in MEL cell differentiation and downregulated during terminal differentiation.
- Post-transcriptional mechanisms control the accumulation and decay of H3.3 mRNAs.
- H3.3 mRNA induction is not affected by deregulated c-myc expression, unlike H1 histone genes.
Conclusions:
- Histone H3.3 gene expression is tightly regulated during erythroid differentiation.
- Regulation of H3.3 mRNA occurs at the post-transcriptional level.
- H3.3 gene regulation during differentiation is independent of c-myc signaling pathways.