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Published on: August 21, 2014
Drosophila MFAP1 is required for pre-mRNA processing and G2/M progression
Ditte S Andersen1, Nicolas Tapon
1Cancer Research UK, London Research Institute, London WC2A 3PX, UK.
Abstract:
The mammalian spliceosome has mainly been studied using proteomics. The isolation and comparison of different splicing intermediates has revealed the dynamic association of more than 200 splicing factors with the spliceosome, relatively few of which have been studied in detail. Here, we report the characterization of the Drosophila homologue of microfibril-associated protein 1 (dMFAP1), a previously uncharacterized protein found in some human spliceosomal fractions ( Jurica, M. S., and Moore, M. J. (2003) Mol. Cell 12, 5-14 ). We show that dMFAP1 binds directly to the Drosophila homologue of Prp38p (dPrp38), a tri-small nuclear ribonucleoprotein component ( Xie, J., Beickman, K., Otte, E., and Rymond, B. C. (1998) EMBO J. 17, 2938-2946 ), and is required for pre-mRNA processing. dMFAP1, like dPrp38, is essential for viability, and our in vivo data show that cells with reduced levels of dMFAP1 or dPrp38 proliferate more slowly than normal cells and undergo apoptosis. Consistent with this, double-stranded RNA-mediated depletion of dPrp38 or dMFAP1 causes cells to arrest in G(2)/M, and this is paralleled by a reduction in mRNA levels of the mitotic phosphatase string/cdc25. Interestingly double-stranded RNA-mediated depletion of a wide range of core splicing factors elicits a similar phenotype, suggesting that the observed G(2)/M arrest might be a general consequence of interfering with spliceosome function.
Insights
Researchers characterized Drosophila microfibril-associated protein 1 (dMFAP1), a spliceosome component essential for cell viability. Depleting dMFAP1 or dPrp38 causes cell cycle arrest and apoptosis, indicating their crucial role in pre-mRNA processing.
Area of Science:
- Molecular Biology
- Cell Biology
- Genetics
Background:
- The spliceosome, a complex molecular machine, orchestrates pre-mRNA splicing, a critical step in gene expression.
- While proteomics studies have identified over 200 splicing factors, detailed functional characterization remains limited for most.
- The Drosophila homologue of microfibril-associated protein 1 (dMFAP1) was identified in human spliceosomal fractions but remained uncharacterized.
Purpose of the Study:
- To characterize the function of dMFAP1, a previously unstudied spliceosome-associated protein in Drosophila.
- To investigate the interaction between dMFAP1 and dPrp38, a known component of the spliceosome.
- To determine the in vivo consequences of dMFAP1 and dPrp38 depletion on cell proliferation, viability, and cell cycle progression.
Main Methods:
- Characterization of dMFAP1 in Drosophila.
- Analysis of dMFAP1 binding to dPrp38.
- Assessment of cell viability and proliferation in response to dMFAP1 and dPrp38 depletion using RNA interference (RNAi).
- Cell cycle analysis (G2/M arrest) and measurement of mRNA levels (string/cdc25) following RNAi-mediated depletion.
Main Results:
- dMFAP1 directly binds to dPrp38, a component of the tri-small nuclear ribonucleoprotein complex.
- dMFAP1 is essential for pre-mRNA processing and viability in Drosophila.
- Reduced levels of dMFAP1 or dPrp38 lead to slower cell proliferation, apoptosis, and G2/M cell cycle arrest.
- Depletion of dMFAP1 or dPrp38 results in decreased mRNA levels of the mitotic phosphatase string/cdc25.
- A G2/M arrest phenotype is observed upon depletion of various core splicing factors, suggesting a general response to spliceosome dysfunction.
Conclusions:
- dMFAP1 is a vital spliceosome component in Drosophila, essential for pre-mRNA processing and cell viability.
- The interaction between dMFAP1 and dPrp38 is critical for normal cellular function.
- Disruption of spliceosome function, including that of dMFAP1 and dPrp38, leads to cell cycle arrest and apoptosis, potentially via regulation of mitotic progression.
- The observed G2/M arrest phenotype associated with splicing factor depletion may represent a conserved cellular response to impaired spliceosome activity.
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