DAPK1–p53 Interaction Converges Necrotic and Apoptotic Pathways of Ischemic Neuronal Death

Abstract

Necrosis and apoptosis are two distinct types of mechanisms that mediate ischemic injury. But a signaling point of convergence between them has yet to be identified. Here, we show that activated death-associated protein kinase 1 (DAPK1), phosphorylates p53 at serine-23 (pS 23 ) via a direct binding of DAPK1 death domain (DAPK1DD) to the DNA binding motif of p53 (p53DM). We uncover that the pS 23 acts as a functional version of p53 and mediates necrotic and apoptotic neuronal death; in the nucleus, pS 23 induces the expression of proapoptotic genes, such as Bax, whereas in the mitochondrial matrix, pS 23 triggers necrosis via interaction with cyclophilin D (CypD) in cultured cortical neurons from mice. Deletion of DAPK1DD (DAPK1 DD⌬ ) or application of Tat-p53DM that interrupts DAPK1-p53 interaction blocks these dual pathways of pS 23 actions in mouse cortical neurons. Thus, the DAPK1-p53 interaction is a signaling point of convergence of necrotic and apoptotic pathways and is a desirable target for the treatment of ischemic insults.

[P2–202]: Dapk1 Signaling Pathways in Stroke: From Mechanisms to Therapies

“…However, the expression of exogenous p53 in the p53 −/− neurons alone in the absence of constitutively active DAPK1 (cDAPK1) does not cause apoptosis, showing that pS23 is an essential substrate of cDAPK1. Recently, Pei et al found that activated DAPK1 phosphorylates p53 at serine-23 (pS23) via a direct binding of DAPK1 death domain (DAPK1DD) to the DNA-binding motif of p53 (p53DM), converging the signaling point of necrotic and apoptotic pathways in stroke [53]. They verified that the pS23 was located in both the mitochondria and the nucleus in the cultured cortical neurons.…”

Intervention of Death-Associated Protein Kinase 1–p53 Interaction Exerts the Therapeutic Effects Against Stroke

“…2,3 To define a promising target that allows a delayed intervention being clinically effective against stroke, we searched for cell death signals downstream of DAPK1. We identified a direct binding of DAPK1 to a DNA-binding motif (DM) of the tumor suppressor protein p53 (p53DM), which is known as a transcriptional regulator of genes that control cell necrosis and apoptosis.…”

“…[4][5][6][7] We thus synthesized a membrane-permeable p53DM peptide consisting of amino acid 271 to 282 (Tat-p53DM) that specifically blocked DAPK1-p53 interaction. 3 Activation of DAPK1 phosphorylates p53 at serine-23 (pS 23 ) in the cultured cortical neurons. 3 In the nucleus, the pS 23 induces expression of the proapoptotic genes such as Bax, whereas in the mitochondrial matrix, the pS 23 interacts with a necrotic factor of cyclophilin D. Application of Tat-p53DM effectively blocks these dual pathways of the pS 23 actions in the cortical cultures in vitro, 3 suggesting that Tat-p53DM could be clinically effective against stroke.…”

“…3 Activation of DAPK1 phosphorylates p53 at serine-23 (pS 23 ) in the cultured cortical neurons. 3 In the nucleus, the pS 23 induces expression of the proapoptotic genes such as Bax, whereas in the mitochondrial matrix, the pS 23 interacts with a necrotic factor of cyclophilin D. Application of Tat-p53DM effectively blocks these dual pathways of the pS 23 actions in the cortical cultures in vitro, 3 suggesting that Tat-p53DM could be clinically effective against stroke. To test this possibility, here we validated the therapeutic effects of Tat-p53DM in vivo in a mouse model with stroke.…”

“…3 We subsequently generated a membranepermeable p53DM peptide by fusing p53DM to the transduction domain of the HIV Tat protein (Tat-p53DM). Our data revealed that Tat-p53DM at a dose of 1 mg/kg (intravenously) effectively intercepted an association between DAPK1 and p53 in brain cells in vivo ( Figure 1A and 1B).…”