Mice knock out for the histone acetyltransferase p300/CREB binding protein-associated factor develop a resistance to amyloid toxicity

Abstract

p300/CREB binding protein-associated factor (PCAF) regulates gene expression by acting through histone acetylation and as a transcription coactivator. Although histone acetyltransferases were involved in the toxicity induced by amyloid-β (Aβ) peptides, nothing is known about PCAF. We here analyzed the sensitivity of PCAF knockout (KO) mice to the toxic effects induced by i.c.v. injection of Aβ 25–35 peptide, a nontransgenic model of Alzheimer's disease. PCAF wild-type (WT) and KO mice received Aβ 25–35 (1, 3 or 9 nmol) or scrambled Aβ 25–35 (9 nmol) as control. After 7 days, Aβ 25–35 toxicity was measured in the hippocampus of WT mice by a decrease in CA1 pyramidal cells and increases in oxidative stress, endoplasmic reticulum stress and induction of apoptosis. Memory deficits were observed using spontaneous alternation, water-maze learning and passive avoidance. Non-treated PCAF KO mice showed a decrease in CA1 cells and learning alterations. However, Aβ 25–35 injection failed to induce toxicity or worsen the deficits. This resistance to Aβ 25–35 toxicity did not involve changes in glutamate or acetylcholine systems. Examination of enzymes involved in Aβ generation or degradation revealed changes in transcription of presenilins, activity of neprilysin (NEP) and an absence of Aβ 25–35-induced regulation of NEP activity in PCAF KO mice, partly due to an altered expression of somatostatin (SRIH). We conclude that PCAF regulates the expression of proteins involved in Aβ generation and degradation, thus rendering PCAF KO insensitive to amyloid toxicity. Modulating acetyltransferase activity may offer a new way to develop anti-amyloid therapies.