Exp Mol Med.  2013 Mar;45(3):e16.

Phosphatidylinositol 4-phosphate 5-kinase alpha negatively regulates nerve growth factor-induced neurite outgrowth in PC12 cells

• Liu T
• Lee SY

Abstract

Neurite outgrowth, a cell differentiation process involving membrane morphological changes, is critical for neuronal network and development. The membrane lipid, phosphatidylinositol (PI) 4,5-bisphosphate (PIP2), is a key regulator of many important cell surface events of membrane signaling, trafficking and dynamics. This lipid is produced mainly by the type I PI 4-phosphate 5-kinase (PIP5K) family members. In this study, we addressed whether PIP5Kalpha, an isoform of PIP5K, could have a role in neurite outgrowth induced by nerve growth factor (NGF). For this purpose, we knocked down PIP5Kalpha in PC12 rat pheochromocytoma cells by stable expression of PIP5Kalpha microRNA that significantly reduced PIP5Kalpha expression and PIP2 level. Interestingly, NGF-induced neurite outgrowth was more prominent in PIP5Kalpha-knockdown (KD) cells than in control cells. Conversely, add-back of PIP5Kalpha into PIP5Kalpha KD cells abrogated the effect of NGF on neurite outgrowth. NGF treatment activated PI 3-kinase (PI3K)/Akt pathway, which seemed to be associated with reactive oxygen species generation. Similar to the changes in neurite outgrowth, the PI3K/Akt activation by NGF was potentiated by PIP5Kalpha KD, but was attenuated by the reintroduction of PIP5Kalpha. Moreover, exogenously applied PIP2 to PIP5Kalpha KD cells also suppressed Akt activation by NGF. Together, our results suggest that PIP5Kalpha acts as a negative regulator of NGF-induced neurite outgrowth by inhibiting PI3K/Akt signaling pathway in PC12 cells.

Keyword

Akt; nerve growth factor; neurite outgrowth; PI3K; phosphatidylinositol 4; 1-phosphatidylinositol-4-phosphate 5-kinase; 5-bisphosphate

MeSH Terms

Animals
Enzyme Activation/drug effects
Gene Knockdown Techniques
Mice
Nerve Growth Factor/*pharmacology
Neurites/drug effects/*enzymology
PC12 Cells
Phosphatidylinositol 3-Kinases/metabolism
Phosphatidylinositol 4,5-Diphosphate/metabolism
Phosphorylation/drug effects
Phosphotransferases (Alcohol Group Acceptor)/*metabolism
Proto-Oncogene Proteins c-akt/metabolism
Rats
Reactive Oxygen Species/metabolism
Signal Transduction/drug effects
Phosphatidylinositol 4,5-Diphosphate
Reactive Oxygen Species
Nerve Growth Factor
Phosphatidylinositol 3-Kinases
Phosphotransferases (Alcohol Group Acceptor)
Proto-Oncogene Proteins c-akt