Ca2 +channel α1 - 1-Subunit transcripts are differentially expressed in rat pheochromocytoma (PC12) cells following nerve growth factor treatment

Abstract

In this report, we describe the effect of nerve growth factor (NGF) on the transcriptional expression of voltage-dependent Ca[2]channel α1 subunits, i.e., α1A, α1B, α1C, α1D, and α1E in rat pheochromocytoma (PC12) cells. Using reverse transcriptase-coupled polymerase chain reaction (RT-PCR) and class-specific Ca[2]channel oligonucleotide probes, messenger RNA levels were measured and compared to Histone H3.3 transcript which remained relatively constant over the duration of NGF treatment. Although no statistically significant differences in P-type (α1A) Ca[2]channel transcript levels were observed, N-type (α1B) Ca[2]channel transcript levels increased 50% over control values (P values < 0.05) at days 7 and 14. In contrast, NGF treatment resulted in decreased levels of L-type (α1C and α1D) transcripts with α1C decreasing steadily to ∼50% of control (P value < 0.01) by 2 weeks, while α1D decreased to ∼20% of control (P value < 0.01) after 2 days treatment. No α1E Ca[2]channel transcripts were detected in PC12 cells. For comparison, PC12 cells were also treated with another differentiative growth factor, i.e., basic fibroblast growth factor (bFGF) and a nondifferentiative growth factor epidermal growth factor (EGF). In contrast to NGF, bFGF and EGF treatment had no inhibitory effect on L-type (α1C and α1D) channel transcript levels after 3 days. Like NGF, EGF treatment had no statistically significant effect upon P-type (α1A) transcript levels but increased in a biphasic manner following bFGF treatment. Presynaptic-associated α1B (N-type) Ca[2]channel transcripts were observed decreased following EGF treatment (2 days) while L-type α1C transcripts decreased after 7 days (P value < 0.01). Although a varied response to differentiative growth factors NGF and bFGF was observed, data presented here indicate that NGF treatment of PC12 cells results in late increased expression of N-type Ca[2]channel transcripts, while L-type (α1C and α1D) Ca[2]channel transcripts appear to be down regulated.