A conserved sequence in calmodulin regulated spectrin-associated protein 1 links its interaction with spectrin and calmodulin to neurite outgrowth

J Neurochem. 2014 Feb;128(3):391-402. doi: 10.1111/jnc.12462. Epub 2013 Oct 24.

Abstract

Calmodulin regulated spectrin-associated protein 1 (CAMSAP1) is a vertebrate microtubule-binding protein, and a representative of a family of cytoskeletal proteins that arose with animals. We reported previously that the central region of the protein, which contains no recognized functional domain, inhibited neurite outgrowth when over-expressed in PC12 cells [Baines et al., Mol. Biol. Evol. 26 (2009), p. 2005]. The CKK domain (DUF1781) binds microtubules and defines the CAMSAP/ssp4 family of animal proteins (Baines et al. 2009). In the central region, three short well-conserved regions are characteristic of CAMSAP-family members. One of these, CAMSAP-conserved region 1 (CC1), bound to both βIIΣ1-spectrin and Ca(2+)/calmodulin in vitro. The binding of Ca(2+)/calmodulin inhibited spectrin binding. Transient expression of CC1 in PC12 cells inhibited neurite outgrowth. siRNA knockdown of CAMSAP1 inhibited neurite outgrowth in PC12 cells or primary cerebellar granule cells: this could be rescued in PC12 cells by wild-type CAMSAP1-enhanced green fluorescent protein, but not by a CC1 mutant. We conclude that CC1 represents a functional region of CAMSAP1, which links spectrin-binding to neurite outgrowth.

Keywords: cytoskeletal regulation; cytoskeleton; molecular evolution; nerve cells; protein domain; protein function.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Axons / physiology
  • Calmodulin / physiology*
  • Computational Biology
  • Conserved Sequence
  • Humans
  • Microtubule-Associated Proteins / genetics*
  • Nerve Tissue Proteins / genetics*
  • Neurites / physiology*
  • PC12 Cells
  • Phylogeny
  • RNA, Small Interfering / genetics
  • Rats
  • Species Specificity
  • Spectrin / physiology*
  • Transfection

Substances

  • CAMSAP1 protein, rat
  • Calmodulin
  • Microtubule-Associated Proteins
  • Nerve Tissue Proteins
  • RNA, Small Interfering
  • Spectrin