PKC and PKA Phosphorylation Affect the Subcellular Localization of Claudin-1 in Melanoma Cells

Amanda D. French, Jennifer L. Fiori, Tura C. Camilli, Poloko D. Leotlela, Michael P. O'Connell, Brittany P. Frank, Sarah Subaran, Fred E. Indig, Dennis D. Taub, Ashani T. Weeraratna

Research output: Contribution to journalArticlepeer-review

Abstract

Cytoplasmic expression of claudin-1 in metastatic melanoma cells correlates to increased migration, and increased secretion of MMP-2 in a PKC dependent manner, whereas claudin-1 nuclear expression is found in benign nevi. Melanoma cells were transfected with a vector expressing CLDN-1 fused to a nuclear localization signal (NLS). Despite significant nuclear localization of claudin-1, there was still transport of claudin-1 to the cytoplasm. Phorbol ester treatment of cells transfected with NLS-claudin-1 resulted in an exclusion of claudin-1 from the nucleus, despite the NLS. To ascertain whether PKC or PKA were involved in this translocation, we mutated the putative phosphorylation sites within the protein. We found that mutating the PKC phosphorylation sites to mimic a non-phosphorylated state did not cause a shift of claudin-1 to the nucleus of the cells, but mutating the PKA sites did. Mutations of either site to mimic constitutive phosphorylation resulted in cytoplasmic claudin-1 expression. Stable claudin-1 transfectants containing non-phosphorylatable PKA sites exhibited decreased motility. These data imply that subcellular localization of claudin-1 can be controlled by phosphorylation, dicating effects on metastatic capacity.

Original languageEnglish (US)
Pages (from-to)93-101
Number of pages9
JournalInternational journal of medical sciences
Volume6
Issue number2
DOIs
StatePublished - Feb 26 2009
Externally publishedYes

Keywords

  • Claudin
  • Melanoma
  • Metastasis
  • PKA
  • PKC

ASJC Scopus subject areas

  • Medicine(all)

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