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Mip/LIN-9 regulates the expression of B-Myb and the induction of cyclin A, cyclin B, and CDK1

Mark Pilkinton1, Raudel Sandoval, Julie Song

  • 1Department of Pharmacology, University of Illinois, Chicago, Illinois 60612, USA.

The Journal of Biological Chemistry
|November 14, 2006
PubMed

Insights

The novel Mip/LIN-9 protein regulates B-Myb expression post-transcriptionally, impacting cell cycle genes. Mip/LIN-9 and B-Myb collaborate to control cell cycle progression through S phase and mitotic cyclins.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Genetics

Background:

  • LIN-9 is a novel protein family member involved in transcription, differentiation, transformation, and cell cycle progression.
  • LIN-9 proteins are conserved across species, including Drosophila Mip130, C. elegans LIN-9, and mammalian LIN-9.

Purpose of the Study:

  • To investigate the interaction between LIN-9 and Myb proteins.
  • To elucidate the role of LIN-9 in regulating B-Myb expression and its impact on cell cycle genes.

Main Methods:

  • Protein interaction studies (co-immunoprecipitation).
  • Western blotting to assess protein levels.
  • Luciferase reporter assays to measure gene expression.
  • Chromatin immunoprecipitation to detect protein binding to promoters.

Main Results:

  • LIN-9 specifically interacts with B-Myb, not c-Myb or A-Myb.
  • Mip/LIN-9 regulates B-Myb expression post-transcriptionally, decreasing B-Myb protein levels upon depletion.
  • Mip/LIN-9 and B-Myb co-regulate the expression of S phase and mitotic genes, including cyclin A and cyclin B.
  • Both Mip/LIN-9 and B-Myb bind to cyclin A and B promoters, with B-Myb binding correlating with peak cyclin expression.

Conclusions:

  • Mip/LIN-9 is essential for B-Myb expression.
  • Mip/LIN-9 and B-Myb function collaboratively to control cell cycle progression by regulating S phase and mitotic cyclins.

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