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Loss of splicing factor ASF/SF2 induces G2 cell cycle arrest and apoptosis, but inhibits internucleosomal DNA fragmentation.

ABSTRACT: ASF/SF2 is an SR protein splicing factor that participates in constitutive and alternative pre-mRNA splicing and is essential for cell viability. Using a genetically modified chicken B-cell line, DT40-ASF, we now show that ASF/SF2 inactivation results in a G2-phase cell cycle arrest and subsequent programmed cell death. However, although several hallmarks of apoptosis are apparent, internucleosomal DNA fragmentation was not detected. Furthermore, inactivation of ASF/SF2 also blocks DNA fragmentation normally induced by a variety of apoptotic stimuli. Notably, mRNA encoding the inhibitor of caspase-activated DNase-L (ICAD-L), which acts as an inhibitor as well as a chaperone of caspase-activated DNase (CAD), decreased in abundance, whereas the level of mRNA encoding ICAD-S, which has only inhibitory activity, increased upon ASF/SF2 depletion. Strikingly, expression of appropriate levels of exogenous human ICAD-L restored apoptotic DNA laddering in ASF/SF2-depleted cells. These results not only indicate that loss of an SR protein splicing factor can induce cell cycle arrest and apoptosis, but also illustrate the important role of ICAD and its regulation by alternative splicing in the process of apoptotic DNA fragmentation.

SUBMITTER: Li X

PROVIDER: S-EPMC1283963 | biostudies-literature | 2005 Nov

REPOSITORIES: biostudies-literature

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Loss of splicing factor ASF/SF2 induces G2 cell cycle arrest and apoptosis, but inhibits internucleosomal DNA fragmentation.

Li Xialu X Wang Jin J Manley James L JL

Genes & development 20051031 22

ASF/SF2 is an SR protein splicing factor that participates in constitutive and alternative pre-mRNA splicing and is essential for cell viability. Using a genetically modified chicken B-cell line, DT40-ASF, we now show that ASF/SF2 inactivation results in a G2-phase cell cycle arrest and subsequent programmed cell death. However, although several hallmarks of apoptosis are apparent, internucleosomal DNA fragmentation was not detected. Furthermore, inactivation of ASF/SF2 also blocks DNA fragmenta ...[more]

PMID: 16260492

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Project description:Our previous study revealed that microRNA (miR) ‑30c represents a potential tumor suppressor gene, the expression of which is associated with decreased oncogenic potential in prostate cancer (PCa) cell lines. However, the functional role and underlying mechanisms of miR‑30c in PCa remain to be fully elucidated. Reverse transcription‑quantitative polymerase chain reaction and immunohistochemical analysis were used to detect the expression levels of alternative splicing factor/splicing factor 2 (ASF/SF2) in PCa tissues. A luciferase reporter assay was used to investigate whether ASF/SF2 may be a direct target gene of miR‑30c. In addition, the effects of miR‑30c on the proliferation and apoptosis of PCa cell lines were examined, following transfection with miR‑30c mimics. Furthermore, correlation analysis was performed to investigate the relationship between the expression of miR‑30c and ASF/SF2 and various clinicopathological parameters of patients with PCa. The present results demonstrated that PCa tissues exhibited higher levels of alternative splicing factor/splicing factor 2 (ASF/SF2), compared with normal tissues. In addition, miR‑30c was revealed to targete the 3'‑untranslated region of the ASF/SF2 gene, causing a decrease in the mRNA and protein levels of ASF/SF2. Furthermore, miR‑30c was reported to decrease cell proliferation, increase the percentage of cells in the G1 cell cycle phase, and promote apoptosis through the inhibition of ASF/SF2. Following correlation analysis using patient samples, the expression of ASF/SF2 was revealed to be tightly correlated with the pathological stage of PCa and biochemical recurrence (BCR). In addition, patients with PCa exhibiting low expression levels of miR‑30c and high expression of ASF/SF2 had significantly lower rates of BCR‑free survival. In conclusion, the present study suggested that the tumor suppressor miR‑30c may be involved in PCa tumorigenesis, possibly via targeting ASF/SF2. The combined analysis of the expression of ASF/SF2 and miR‑30c may be a valuable tool for early prediction of BCR in patients with PCa following radical prostatectomy.

Dataset Information

Loss of splicing factor ASF/SF2 induces G2 cell cycle arrest and apoptosis, but inhibits internucleosomal DNA fragmentation.

Publications

Loss of splicing factor ASF/SF2 induces G2 cell cycle arrest and apoptosis, but inhibits internucleosomal DNA fragmentation.

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