Ca2+ channel alpha 1-subunit transcripts are differentially expressed in rat pheochromocytoma (PC12) cells following...

In this report, we describe the effect of nerve growth factor (NGF) on the transcriptional expression of voltage-dependent Ca2+ channel alpha 1 subunits, i.e., alpha 1A, alpha 1B, alpha 1C, alpha 1D, and alpha 1E in rat pheochromocytoma (PC12) cells. Using reverse transcriptase-coupled polymerase chain reaction (RT-PCR) and class-specific Ca2+ 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 (alpha 1A) Ca2+ channel transcript levels were observed, N-type (alpha 1B) Ca2+ 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 (alpha 1C and alpha 1D) transcripts with alpha 1C decreasing steadily to approximately 50% of control (P value < 0.01) by 2 weeks, while alpha 1D decreased to approximately 20% of control (P value < 0.01) after 2 days treatment. No alpha 1E Ca2+ 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 (alpha 1C and alpha 1D) channel transcript levels after 3 days. Like NGF, EGF treatment had no statistically significant effect upon P-type (alpha 1A) transcript levels but increased in a biphasic manner following bFGF treatment. Presynaptic-associated alpha 1B (N-type) Ca2+ channel transcripts were observed decreased following EGF treatment (2 days) while L-type alpha 1C 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 Ca2+ channel transcripts, while L-type (alpha 1C and alpha 1D) Ca2+ channel transcripts appear to be down regulated.