Nuclear-localized Asunder regulates cytoplasmic dynein localization via its role in the integrator complex

Mol Biol Cell. 2013 Sep;24(18):2954-65. doi: 10.1091/mbc.E13-05-0254. Epub 2013 Jul 31.

Abstract

We previously reported that Asunder (ASUN) is essential for recruitment of dynein motors to the nuclear envelope (NE) and nucleus-centrosome coupling at the onset of cell division in cultured human cells and Drosophila spermatocytes, although the mechanisms underlying this regulation remain unknown. We also identified ASUN as a functional component of Integrator (INT), a multisubunit complex required for 3'-end processing of small nuclear RNAs. We now provide evidence that ASUN acts in the nucleus in concert with other INT components to mediate recruitment of dynein to the NE. Knockdown of other individual INT subunits in HeLa cells recapitulates the loss of perinuclear dynein in ASUN-small interfering RNA cells. Forced localization of ASUN to the cytoplasm via mutation of its nuclear localization sequence blocks its capacity to restore perinuclear dynein in both cultured human cells lacking ASUN and Drosophila asun spermatocytes. In addition, the levels of several INT subunits are reduced at G2/M when dynein is recruited to the NE, suggesting that INT does not directly mediate this step. Taken together, our data support a model in which a nuclear INT complex promotes recruitment of cytoplasmic dynein to the NE, possibly via a mechanism involving RNA processing.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Carrier Proteins / chemistry
  • Carrier Proteins / metabolism*
  • Cell Cycle Proteins / chemistry
  • Cell Cycle Proteins / metabolism*
  • Cell Division
  • Cell Nucleus / metabolism*
  • Cytoplasmic Dyneins / metabolism*
  • Drosophila Proteins / chemistry
  • Drosophila Proteins / metabolism*
  • Drosophila melanogaster / cytology
  • Drosophila melanogaster / metabolism*
  • G2 Phase
  • HeLa Cells
  • Humans
  • Male
  • Molecular Sequence Data
  • Multiprotein Complexes / metabolism*
  • Nuclear Envelope / metabolism
  • Nuclear Localization Signals / metabolism
  • Protein Subunits / metabolism
  • Protein Transport
  • RNA, Small Interfering / metabolism
  • Spermatocytes / cytology
  • Spermatocytes / metabolism
  • Subcellular Fractions / metabolism

Substances

  • Carrier Proteins
  • Cell Cycle Proteins
  • Drosophila Proteins
  • INTS13 protein, human
  • Multiprotein Complexes
  • Nuclear Localization Signals
  • Protein Subunits
  • RNA, Small Interfering
  • asun protein, Drosophila
  • Cytoplasmic Dyneins