Effect of Aβ exposure on the mRNA expression patterns of voltage-sensitive calcium channel α1 subunits (α1A-α1D) in human SK-N-SH neuroblastoma

Evidence for loss of Ca2+ homeostasis through voltage-sensitive Ca2+ channels (VSCCs) contribution to neuronal degeneration induced by beta-amyloid protein (A beta) is considerable and rapidly increasing. Thus, the expression patterns of four alpha(1) subunits for P/Q (alpha(1A))-, N (alpha(1B))-, and L (alpha(1C) and alpha(1D))-type VSCCs before and after A beta exposure were investigated in human SK-N-SH neuroblastoma. Reverse transcription-polymerase chain reaction (RT-PCR) analysis showed a constitutive and abundant co-expression of mRNA for U I A and alpha I D subunit in control cells. The mRNA expression of another L-type subunit alpha(1C) was undetectable in control cells while N-type subunit alpha(1B) was relative lower when compared to alpha(1A) and (X I D subunits. Interestingly, mRNA levels of alpha(1A), alpha(1B), and alpha(1C) were remarkably and time-dependently increased in response to A beta (20 mu M) for 72 h culture period. In contrast, the constitutively expressed U. I D mRNA was not further modified during A beta exposure. Western blot analysis of four alpha(1) subunits expression was consistent with the findings obtained by RT-PCR. In conclusion, our results suggested that P/Q-, N-, as well as L-type Ca2+ channel genes might be existed in S K-N-SH cells. Among them, mRNA for alpha(1A), alpha(1B), and alpha(1D) were expressed constitutively while alpha(1C) were inducible. Furthermore, A beta exposure selectively modulates the transcription alpha(1A), alpha(1B), and alpha(1C) subunits. These suggested that except activating of existed VSCCs, up-regulation of alpha(1) subunits expression might also contribute to A beta-induced neuronal toxicity and the complex of these VSCCs expression may participate in Ca2+ current disturbance in Alzheimer's disease. (c) 2006 Elsevier Ltd. All rights reserved.