Overload of intracellular Ca²⁺ has been implicated in the pathogenesis of neuronal disorders, such as Alzheimer’s disease. Various mechanisms produce abnormalities in intracellular Ca²⁺ homeostasis systems. L-type Ca²⁺ chan-nels have been known to be closely involved in the mecha-nisms underlying the neurodegenerative properties of amyloid-beta (Abeta) peptides. However, most studies of L-type Ca²⁺ channels in Abeta-related mechanisms have been limited to CaV1.2, and surprisingly little is known about the involvement of CaV1.3 in Abeta-induced neuronal toxicity. In the present study, we examined the expression patterns of CaV1.3 after Abeta25-35 exposure for 24 h and compared them with the expression patterns of CaV1.2. The expression levels of CaV1.3 were not significantly changed by Abeta25-35 at both the mRNA levels and the total protein level in cultured hippocampal neurons. However, surface protein levels of CaV1.3 were significantly increased by Abeta25-35, but not by Abeta35-25. We next found that acute treatment with A?25-35 increased CaV1.3 channel activities in HEK293 cells using whole-cell patch-clamp recordings. Furthermore, using GTP pulldown and co-immunoprecipitation assays in HEK293 cell lysates, we found that amyloid precursor protein interacts with beta3 subunits of Ca2+ channels instead of CaV1.2 or CaV1.3 alpha1 subunits. These results show that A?25-35 chronically or acutely upregulates CaV1.3 in the rat hippocampal and human kidney cells (HEK293). This suggests that CaV1.3 has a potential role along with CaV1.2 in the pathogenesis of Alzheimer’s disease.

Keywords: Alzheimer’s disease, co-immunoprecipitation, GST pulldown, intracellular Ca²⁺ L-type Ca²⁺ channels