Tissue-specific degradation of essential centrosome components reveals distinct microtubule populations at microtubule organizing centers

PLoS Biol. 2018 Aug 6;16(8):e2005189. doi: 10.1371/journal.pbio.2005189. eCollection 2018 Aug.

Abstract

Non-centrosomal microtubule organizing centers (ncMTOCs) are found in most differentiated cells, but how these structures regulate microtubule organization and dynamics is largely unknown. We optimized a tissue-specific degradation system to test the role of the essential centrosomal microtubule nucleators γ-tubulin ring complex (γ-TuRC) and AIR-1/Aurora A at the apical ncMTOC, where they both localize in Caenorhabditis elegans embryonic intestinal epithelial cells. As at the centrosome, the core γ-TuRC component GIP-1/GCP3 is required to recruit other γ-TuRC components to the apical ncMTOC, including MZT-1/MZT1, characterized here for the first time in animal development. In contrast, AIR-1 and MZT-1 were specifically required to recruit γ-TuRC to the centrosome, but not to centrioles or to the apical ncMTOC. Surprisingly, microtubules remain robustly organized at the apical ncMTOC upon γ-TuRC and AIR-1 co-depletion, and upon depletion of other known microtubule regulators, including TPXL-1/TPX2, ZYG-9/ch-TOG, PTRN-1/CAMSAP, and NOCA-1/Ninein. However, loss of GIP-1 removed a subset of dynamic EBP-2/EB1-marked microtubules, and the remaining dynamic microtubules grew faster. Together, these results suggest that different microtubule organizing centers (MTOCs) use discrete proteins for their function, and that the apical ncMTOC is composed of distinct populations of γ-TuRC-dependent and -independent microtubules that compete for a limited pool of resources.

Publication types

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

MeSH terms

  • Animals
  • Aurora Kinase A
  • Caenorhabditis elegans / metabolism
  • Caenorhabditis elegans Proteins / metabolism
  • Carrier Proteins / metabolism
  • Centrosome / metabolism*
  • Centrosome / physiology
  • Cytoskeletal Proteins / metabolism
  • Epithelial Cells / metabolism
  • Microtubule-Associated Proteins
  • Microtubule-Organizing Center / metabolism
  • Microtubule-Organizing Center / physiology*
  • Microtubules / metabolism*
  • Microtubules / physiology
  • Nuclear Proteins / metabolism
  • Organ Specificity
  • Tubulin / metabolism

Substances

  • Caenorhabditis elegans Proteins
  • Carrier Proteins
  • Cytoskeletal Proteins
  • Microtubule-Associated Proteins
  • NOCA-1 protein, C elegans
  • Nuclear Proteins
  • PTRN-1 protein, C elegans
  • TPXL-1 protein, C elegans
  • Tubulin
  • Aurora Kinase A
  • air-1 protein, C elegans