Death-associated protein kinase 1 (DAPK1) is a calcium/calmodulin-regulated serine/threonine kinase that plays a pivotal role in regulating neuronal cell death via both apoptotic and autophagic pathways [1]. Aberrant DAPK1 activation has been implicated in neuronal damage under pathological conditions such as ischemic stroke, traumatic brain injury (TBI) [2], epilepsy [3], and various neurodegenerative disorders [4]. The overexpression or sustained activation of DAPK1 exacerbates neuronal vulnerability to injury by amplifying intracellular stress responses and inhibiting survival pathways [5]. Given its central role in multiple neurological conditions, DAPK1 has emerged as a potential therapeutic target for mitigating progressive neuronal loss [6]. Despite its therapeutic potential, the development of effective DAPK1-targeted agents has been hampered by several challenges. Most of the currently reported DAPK1 inhibitors [[7], [8], [9], [10], [11]] exhibit poor kinase selectivity, limited brain penetration, and suboptimal in vivo activity, precluding their clinical translation (Fig. 1).

With the continuous development of the field of drug development, several new drug development technologies have emerged, among which PROteolysis TArgeting Chimeras (PROTACs) technology has attracted the attention of many researchers. PROTACs have developed rapidly in the past two decades [[12], [13], [14]] since they were first reported in 2001 [15]. PROTAC is a bifunctional molecule composed of a ligand for the target protein (protein of interest, POI) and an E3 ubiquitin ligase recruitment ligand, which are linked together by an appropriate linker. PROTAC forms a ternary complex with the POI and E3 ligase, causing the POI to undergo multiple types of ubiquitination. It is subsequently recognized and degraded by the 26S proteasome through the ubiquitin–proteasome system (Fig. 2). Unlike traditional small-molecule inhibitors, PROTAC technology operates in a “catalytic” manner. Theoretically, only a catalytic dose is required to induce the continuous degradation of the POI, thereby resulting in high potency, high selectivity, and reduced toxicity. Moreover, since the efficacy of PROTACs primarily depends on the stability of the ternary complex formed, this approach is also applicable to targets traditionally deemed “undruggable” without active pockets and those susceptible to drug-resistant mutations [16].

In addition, PROTACs have been widely applied to various disease targets at present, including mutant huntingtin (mHTT) [17], Tau [18], GSK3 [19], ERRα [20], AR [21], PARP1 [22], AKT [23], BTK [24], ALK [25], and SHP2 [26]. PROTACs are now widely utilized by pharmaceutical companies for clinical drug development, and several of them have already progressed into clinical trials [27,28]. Among these compounds, the PROTAC compound ARV-471 exhibited significant therapeutic efficacy in a phase 3 trial for breast cancer treatment, highlighting the substantial drug development potential of PROTAC technology.

Here we describe the design, synthesis, and evaluation of first-in-class PROTAC-based DAPK1 degraders by conjugating the DAPK1 inhibitor HS38 with CRBN ligands. Our efforts culminated in the identification of CP1 as a highly potent DAPK1 degrader, effectively inducing DAPK1 degradation in SH-SY5Y cells at low micromolar concentrations.