Over-expression of phospholipase D isozymes down-regulates protein kinase CKII activity via proteasome-dependent CKIIβ degradation in NIH3T3 cells

Soo Hyun Yoon, Do Sik Min, Young Seuk Bae

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Over-expression of phospholipase D (PLD) 1 or PLD2 down-regulated CKII activity in NIH3T3 cells. The same results were found with catalytically inactive mutants of PLD isozymes, indicating that the catalytic activity of PLD is not required for PLD-mediated CKII inhibition. Consistent with this, 1-butanol did not alter CKII activity. The reduction in CKII activity in PLD-over-expressing NIH3T3 cells was due to reduced protein level, but not mRNA level, of the CKIIβ subunit. This PLD-induced CKIIβ degradation was mediated by ubiquitin-proteasome machinery, but MAP kinase and mTOR were not involved in CKIIβ degradation. PLD isozymes interacted with the CKIIβ subunit. Immunocyto-chemical staining revealed that PLD and CKIIβ colocalize in the cytoplasm of NIH3T3 cells, especially in the perinuclear region. PLD binding to CKIIβ inhibited CKIIβ autophosphory-lation, which is known to be important for CKIIβ stability. In summary, the current data indicate that PLD isozymes can down-regulate CKII activity through the acceleration of CKIIβ degradation by ubiquitin-proteasome machinery.

Original languageEnglish
Pages (from-to)299-305
Number of pages7
JournalMolecules and cells
Issue number3
Publication statusPublished - 2009 Mar 1


All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Cell Biology

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