Regulation of the tubulin polymerization-promoting protein by Ca2+/S100 proteins

Seita Doi, Naoki Fujioka, Satomi Ohtsuka, Rina Kondo, Maho Yamamoto, Miwako Denda, Masaki Magari, Naoki Kanayama, Naoya Hatano, Ryo Morishita, Takafumi Hasegawa, Hiroshi Tokumitsu

Research output: Contribution to journalArticlepeer-review

Abstract

To elucidate S100 protein-mediated signaling pathways, we attempted to identify novel binding partners for S100A2 by screening protein arrays carrying 19,676 recombinant glutathione S-transferase (GST)-fused human proteins with biotinylated S100A2. Among newly discovered putative S100A2 interactants, including TMLHE, TRH, RPL36, MRPS34, CDR2L, OIP5, and MED29, we identified and characterized the tubulin polymerization-promoting protein (TPPP) as a novel S100A2-binding protein. We confirmed the interaction of TPPP with Ca2+/S100A2 by multiple independent methods, including the protein array method, S100A2 overlay, and pulldown assay in vitro and in transfected COS-7 cells. Based on the results from the S100A2 overlay assay using various GST-TPPP mutants, the S100A2-binding region was identified in the C-terminal (residues 111–160) of the central core domain of a monomeric form of TPPP that is involved in TPPP dimerization. Chemical cross-linking experiments indicated that S100A2 suppresses dimer formation of His-tagged TPPP in a dose-dependent and a Ca2+-dependent manner. In addition to S100A2, TPPP dimerization is disrupted by other multiple S100 proteins, including S100A6 and S100B, in a Ca2+-dependent manner but not by S100A4. This is consistent with the fact that S100A6 and S100B, but not S100A4, are capable of interacting with GST-TPPP in the presence of Ca2+. Considering these results together, TPPP was identified as a novel target for S100A2, and it is a potential binding target for other multiple S100 proteins, including S100A6 and S100B. Direct binding of the S100 proteins with TPPP may cause disassembly of TPPP dimer formation in response to the increasing concentration of intracellular Ca2+, thus resulting in the regulation of the physiological function of TPPP, such as microtubule organization.

Original languageEnglish
Article number102404
JournalCell Calcium
Volume96
DOIs
Publication statusPublished - Jun 2021

Keywords

  • Calcium signaling
  • Dimerization
  • Genomewide screening
  • Intracellular calcium signal transduction
  • Microtubule organization
  • Multiple system atrophy
  • Oligodendrocytes
  • Parkinson's disease
  • Protein active array
  • Protein-protein interaction
  • S100A2
  • S100A6
  • S100B
  • TPPP
  • Tubulin polymerization-promoting protein
  • α-Synuclein

ASJC Scopus subject areas

  • Physiology
  • Molecular Biology
  • Cell Biology

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