Zyxin is a novel target for beta‐amyloid peptide: characterization of its role in Alzheimer's pathogenesis

Abstract

Zyxin is an adaptor protein recently identified as a novel regulator of the homeodomain-interacting protein kinase 2 (HIPK2)-p53 signaling in response to DNA damage. We recently reported an altered conformational state of p53 in tissues from patients with Alzheimer 's disease (AD), because of a deregulation of HIPK2 activity, leading to an impaired and dysfunctional response to stressors. Here, we examined the molecular mechanisms underlying the deregulation of HIPK2 activity in two cellular models, HEK-293 cells and SH-SY5Y neuroblastoma cells differentiated with retinoic acid overexpressing the amyloid precursor protein, focusing on the evidence that zyxin expression is important to maintain HIPK2 protein stability. We demonstrated that both beta-amyloid (Ab) 1-40 and 1-42 induce zyxin deregulation, thus affecting the transcriptional repressor activity of HIPK2 onto its target promoter, metallothionein 2A, which is in turn responsible for the induction of an altered conformational state of p53. We demonstrate for the first time that zyxin is a novel target of Ab activities in AD. These results may help the studies on the pathogenesis of AD, through the fine dissection of events related to beta-amyloid activities. Keywords: Alzheimer's disease, beta-amyloid peptides, conformationally altered p53, metallothionein 2A, zyxin. The protein p53 responds to a variety of cellular stresses and is able to sense the intensity of the damage and modulate biological responses, ranging from transient growth arrest to permanent replicative senescence or apoptosis (Vousden and Prives 2005). One important mechanism that controls p53 function is its conformational stability (Joerger and Fersht 2007). An altered protein conformational state of p53, independent from point mutations, has been reported in tissues from patients with Alzheimer's disease (AD) (Uberti et al. 2006;Lanni et al. 2008;Zhou and Jia 2010). When investigating the mechanism of such alteration, we found that soluble nanomolar concentrations of beta-amyloid (Ab) 1-40 peptide induced the expression of an unfolded p53 protein isoform and modulated p53 functions by interfering with the homeodomain-interacting protein kinase 2 (HIPK2) (Lanni et al. 2007(Lanni et al. , 2010, a fundamental protein in maintaining wildtype p53 function (Puca et al. 2008). In particular, soluble Ab 1-40 inhibited HIPK2 activity, consequently inducting an altered conformational state of p53, and thus resulting in an inability to properly activate an apoptotic program when cells are exposed to a noxious stimulus (Lanni et al. 2010).A novel regulator of the HIPK2-p53 signaling in response to DNA damage, named zyxin, has been recently identified (Crone et al. 2011). Zyxin is primarily localized at the focal Received January 2, 2013; revised manuscript received January 11, 2013; accepted January 11, 2013. Address correspondence and reprint requests to Cristina Lanni, Department of Drug Sciences, University of Pavia, Viale Taramelli 14, 27100 Pavia, Italy. E-mail: cristina.lanni@unipv...

Nature‐Inspired Multifunctional Ligands: Focusing on Amyloid‐Based Molecular Mechanisms of Alzheimer's Disease

“…We first characterized SH‐SY5Y neuroblastoma cells in terms of HIPK2 and zyxin expression and the conformational status of p53. In agreement with our previous data, a sub‐lethal concentration of Aβ 42 (10 n m ) significantly decreased the protein levels of HIPK2 and zyxin (Figure a).…”

“…Loss of the wild‐type conformation and function of p53 induced by soluble nontoxic Aβ has been shown to contribute to the accumulation of cell damage, which makes cells unable to activate the proper apoptotic program if exposed to noxae . In light of this evidence, we sought to study cell sensitivity to doxorubicin, a genotoxic agent able to induce apoptosis in a p53‐dependent manner, following treatment with 10 n m Aβ 42 in the presence and absence of 5 μ m 1 – 3 .…”

“…The activity of HIPK2 is in turn fundamental in maintaining the function of wild‐type p53, as it controls the destiny of cells upon exposure to DNA‐damaging agents. In particular, soluble Aβ peptides downregulate zyxin expression, which is fundamental in maintaining the stability of HIPK2 and in turn the activity of p53 . This Aβ‐mediated downregulation may be responsible for early pathological changes that precede the amyloidogenic pathway in the neurodegenerative cascade.…”

Shared genes between Alzheimer’s disease and ischemic stroke

“…Zyxin ( ZYX ) encodes a zinc‐binding adaptor protein that translocates from focal adhesions to the nucleus to conduct signal transduction and modulate gene expression. Recently, zyxin has been identified as a novel target of Aβ metabolism in AD . Besides, Zyxin is a novel interacting partner of SIRT1 that is protective against aging‐associated pathologies like AD and IS .…”

“…Recently, zyxin has been identified as a novel target of Aβ metabolism in AD. 26 Besides, Zyxin is a novel interacting partner of SIRT1 27 that is protective against aging-associated pathologies like AD 28 and IS. 29 Here, ZYX was jointly associated with AD and IS (P combined = 2.63E−07) with P < 0.001 in each disease.…”