Depolarization-induced neurite outgrowth in PC12 cells requires permissive, low level NGF receptor stimulation and activation of calcium/calmodulin-dependent protein kinase

Abstract

Neuronal activity is required for normal neural development. Excessive activity can cause abnormal growth of neural processes and may contribute to formation of epileptic foci. Using PC12 cells, we investigated mechanisms by which depolarization regulates neurite growth. Depolarization with 45 mM KCl induced neurite outgrowth only if NGF receptors were partly activated by overexpression of p140trkA or by treatment with a low concentration of NGF that alone was insufficient to stimulate neurite formation. Depolarization-induced neurite growth was reduced by inhibitors of L-type Ca2+ channels, Ca2+/calmodulin-dependent protein (CaM) kinases II and IV, and transcription. These results identify a novel mechanism by which depolarizing stimuli synergize with subthreshold activation of NGF receptors to induce neurite growth through a Ca2+ and CaM kinase-dependent signal transduction pathway.

Involvement of the Na+/Ca2+ exchanger isoform 1 (NCX1) in Neuronal Growth Factor (NGF)-induced Neuronal Differentiation through Ca2+-dependent Akt Phosphorylation

“…Particularly the MAPK pathway is required for growth factor-induced differentiation of PC12 cells, although it is not sufficient for neurite outgrowth (5). In fact, MAPK activation appears to be a permissive signal for neurite extension in response to growth factor stimuli and calcium signaling (6). Furthermore, activation of PI3K/Akt signaling has been shown to mediate a number of processes, including NGF-induced neurite outgrowth in PC12 cells (7).…”

Regulation of Axonal Extension and Growth Cone Motility by Calmodulin-Dependent Protein Kinase I

“…We first explored the possible involvement of CaMKII, a multifunctional kinase known to regulate several neuronal functions (for review, see Soderling et al, 2001;Lisman et al, 2002), because it had been implicated in previous studies (Zheng et al, 1994;Solem et al, 1995;Williams et al, 1995;Kuhn et al, 1998;Vaillant et al, 2002). Rather than using KN-62, which inhibits various CaMK family members, we overexpressed CaMKIIN, an endogenous protein inhibitor of CaMKII (Chang et al, 1998.…”

“…Many stimulatory effects of Ca 2ϩ on neurite outgrowth are blocked by the compound 1-[N,O-bis(5-isoquinolinesulfonyl)-N-methyl-L-tyrosyl]-4-phenylpiperazine (KN-62) (Zheng et al, 1994;Solem et al, 1995;Williams et al, 1995;Kuhn et al, 1998;Vaillant et al, 2002). Because KN-62 was originally thought to be a specific calmodulin kinase II (CaMKII) inhibitor (Tokumitsu et al, 1990), it was assumed that CaMKII mediated these stimulatory Ca 2ϩ effects; however, KN-62 is now recognized to also inhibit CaMKIV and CaMKI (Mochizuki et al, 1993;Enslen et al, 1994).…”

Overexpression of an α1H (Cav3.2) T-type Calcium Channel during Neuroendocrine Differentiation of Human Prostate Cancer Cells

“…Calcium entry through voltage-gated calcium channels is reported to be involved in differentiation and neurite outgrowth in other cells (12)(13)(14)(15). It has been shown, for example, in the pheochromocytoma cell line (PC12 cells) that neuroendocrine differentiation is accompanied by an increased expression of voltage-dependent channels like low-voltage activated (LVA) (12) and high-voltage activated (HVA) calcium channels (14,16).…”