Abstract
The aim of the present study was to investigate whether KV3.4 channel subunits are involved in neuronal death induced by neurotoxic β-amyloid peptides (Aβ). In particular, to test this hypothesis, three main questions were addressed: 1) whether the Aβ peptide can up-regulate both the transcription/translation and activity of KV3.4 channel subunit and its accessory subunit, MinK-related peptide 2 (MIRP2); 2) whether the increase in KV3.4 expression and activity can be mediated by the nuclear factor-κB (NF-κB) family of transcriptional factors; and 3) whether the specific inhibition of KV3.4 channel subunit reverts the Aβ peptide-induced neurodegeneration in hippocampal neurons and nerve growth factor (NGF)-differentiated PC-12 cells. We found that Aβ1–42 treatment induced an increase in KV3.4 and MIRP2 transcripts and proteins, detected by reverse transcription-polymerase chain reaction and Western blot analysis, respectively, in NGF-differentiated PC-12 cells and hippocampal neurons. Patch-clamp experiments performed in whole-cell configuration revealed that the Aβ peptide caused an increase in IA current amplitude carried by KV3.4 channel subunits, as revealed by their specific blockade with blood depressing substance-I (BDS-I) in both hippocampal neurons and NGF-differentiated PC-12 cells. The inhibition of NF-κB nuclear translocation with the cell membrane-permeable peptide SN-50 prevented the increase in KV3.4 protein and transcript expression. In addition, the SN-50 peptide was able to block Aβ1–42-induced increase in KV3.4 K+ currents and to prevent cell death caused by Aβ1–42 exposure. Finally, BDS-I produced a similar neuroprotective effect by inhibiting the increase in KV3.4 expression. As a whole, our data indicate that KV3.4 channels could be a novel target for Alzheimer's disease pharmacological therapy.
Footnotes
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This study was supported by grants from the Italian Ministry of Health Programma Speciale art. 12bis comma 6, D. Lgs. 229/99; Special Project “Alzheimer 2001/2004” (to L.A. and M.T.), COFIN-MIUR 2002 (to L.A.), COFIN 2004 (to L.A.), PNR-FIRB RBNE01E7YX_007 2001, Regione Campania GEAR, Ricerca Finalizzata Ministero della Salute legge 502/92 “Geni Vulnerabiltà e di Riparazione DNA” (to L.A.), and POP and legge 41 from Regione Campania, 12th Italian-Chinese executive program for scientific and technological cooperation for the period 2006 to 2009 from the Italian Foreign Ministry (to L.A.).
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Article, publication date, and citation information can be found at http://molpharm.aspetjournals.org.
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doi:10.1124/mol.107.034868.
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ABBREVIATIONS: KV channels, voltage-gated K+ channels; Aβ, β-amyloid peptide; Aβ1–42, β-amyloid peptide 1–42; AD, Alzheimer's disease; BDS-I, blood depressing substance-I; GAPDH, glyceraldehyde 3-phosphate dehydrogenase; IA, fast inactivating K+ currents; MIRP, MinK-related peptide; NGF, nerve growth factor; NF-κB, nuclear factor κB; PBS, phosphate-buffered saline; RT-PCR, reverse transcription polymerase chain reaction; ANOVA, analysis of variance; bp, base pair(s); SN-50, NF-κB cell-permeable inhibitory peptide (AAVALLPAVLLALLAPVQRKRQKLMP).
- Received February 7, 2007.
- Accepted May 10, 2007.
- The American Society for Pharmacology and Experimental Therapeutics
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