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Requiem: a novel zinc finger gene essential for apoptosis in myeloid cells
T G Gabig1, P L Mantel, R Rosli
1Department of Medicine, Indiana University School of Medicine, Indianapolis 46202-5121.
Abstract:
To identify genes mediating programmed cell death triggered by interleukin 3 (IL-3)-deprivation of myeloid cells, the IL-3-dependent murine myeloid cell line FDCP-1 was used to screen a mammalian cell expression library for cDNAs that would promote survival following withdrawal of IL-3. A unique 892-base pair cDNA was cloned that prevented the programmed cell death response following IL-3 deprivation by causing antisense suppression of an endogenous 2.4-kilobase (kb) mRNA. A 2.3-kb cDNA containing the identical 892-base pair over-lapping sequence was cloned that encoded a deduced 371-amino acid protein containing a single Kruppel-type zinc finger and a cluster of 4 cysteine/histidine-rich repeats resembling atypical zinc fingers. The 2.4-kb mRNA was found to be ubiquitously expressed in murine tissues and its abundance in FDCP-1 cells was not altered in response to IL-3 deprivation. Since expression of this 2.4-kb mRNA was a prerequisite for the apoptosis response following IL-3 deprivation, the gene encoding it was named requiem. Requiem is likely to encode a transcription factor required for the apoptosis response following survival factor withdrawal from myeloid cells.
Insights
Researchers identified the gene "requiem," which is essential for programmed cell death in myeloid cells when interleukin-3 (IL-3) is withdrawn. This discovery sheds light on survival factor withdrawal and apoptosis.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- Interleukin-3 (IL-3) is crucial for myeloid cell survival.
- IL-3 deprivation triggers programmed cell death (apoptosis) in dependent cells.
- Identifying genes involved in this process is key to understanding cell survival regulation.
Purpose of the Study:
- To identify genes mediating programmed cell death in myeloid cells upon IL-3 withdrawal.
- To clone and characterize cDNAs that confer survival against IL-3 deprivation.
Main Methods:
- Screening a mammalian cell expression library using the IL-3-dependent FDCP-1 cell line.
- Cloning of survival-promoting cDNAs and antisense suppression of endogenous mRNA.
- Sequence analysis of cloned cDNAs and protein products.
- Analysis of mRNA expression patterns in murine tissues and cell lines.
Main Results:
- A unique 892-bp cDNA was cloned that prevented apoptosis via antisense suppression of a 2.4-kb mRNA.
- A 2.3-kb cDNA encoding a 371-amino acid protein with a zinc finger and cysteine/histidine-rich repeats was identified.
- The 2.4-kb mRNA was ubiquitously expressed and its levels were unaffected by IL-3 deprivation.
- Expression of the 2.4-kb mRNA was a prerequisite for IL-3 deprivation-induced apoptosis.
Conclusions:
- The gene encoding the 2.4-kb mRNA was named "requiem."
- Requiem likely functions as a transcription factor essential for initiating apoptosis upon survival factor withdrawal in myeloid cells.