RRC ID 51976
Author Kawabata N, Matsuda M.
Title Cell Density-Dependent Increase in Tyrosine-Monophosphorylated ERK2 in MDCK Cells Expressing Active Ras or Raf.
Journal PLoS One
Abstract The extracellular signal-regulated kinase (ERK) is one of the principal hub proteins that transmit growth signals from upstream oncogene products including Ras and BRaf to downstream effector proteins. However, there are both reports supporting and refuting the increase in ERK activity in cancer tissues expressing the active Ras and BRaf proteins. We considered that the cell density might account for this discrepancy. To examine this possibility, we prepared Madin-Darby canine kidney (MDCK) cells that expressed an active HRas, NRas, KRas, or BRaf and an ERK biosensor based on the principle of Förster resonance energy transfer (FRET). As we anticipated, expression of the active Ras or BRaf increased ERK activity at low cell densities. However, the ERK activity was markedly suppressed at high cell densities irrespective of the expression of the active Ras or BRaf. Western blotting analysis with Phos-tag gel revealed the decrease of tyrosine and threonine-diphosphorylated active ERK and the increase of tyrosine-monophosphorylated inactive ERK at high cell density. In addition, we found that calyculin A, an inhibitor for PPP-subfamily protein serine/threonine phosphatases, decreased the tyrosine-monophosphorylated ERK. Our study suggests that PPP-subfamily phosphatases may be responsible for cell density-dependent ERK dephosphorylation in cancer cells expressing active Ras or BRaf protein.
Volume 11(12)
Pages e0167940
Published 2016-1-1
DOI 10.1371/journal.pone.0167940
PII PONE-D-16-37659
PMID 27936234
PMC PMC5148048
MeSH Animals Dogs Madin Darby Canine Kidney Cells Mitogen-Activated Protein Kinase 1 / metabolism* Phosphorylation Proto-Oncogene Proteins B-raf / metabolism* Proto-Oncogene Proteins c-akt / metabolism Ribosomal Protein S6 Kinases / metabolism Tyrosine / metabolism* Wound Healing ras Proteins / metabolism*
IF 2.74
Times Cited 6
Human and Animal Cells MDCK(RCB0995)