Requirement for Serine-384 in Caspase-2 processing and activity

Abstract

Caspase-2 is a unique and conservative cysteine protease which plays an important role in several cellular processes including apoptotic cell death. Although the molecular mechanisms of its activation remain largely unclear, a major role belongs to the architecture of the caspase-2 active center. We demonstrate that the substitution of the putative phosphorylation site of caspase-2, Serine-384 to Alanine, blocks caspase-2 processing and decreases its enzymatic activity. Strikingly, in silico analysis using molecular dynamics simulations has shown that Serine-384 is crucially involved in interactions within the caspase-2 active center. It stabilizes Arginine-378, which forms a crucial hydrogen bond with the aspartate residue of a substrate. Hence, Serine-384 is essential for supporting a proper architecture of the active center of caspase-2. Moreover, molecular modeling strongly proved steric inaccessibility of Ser-384 to be phosphorylated. Importantly, a multiple alignment has demonstrated that both Serine-384 and Arg-378 residues are highly conservative across all members of caspase family, which allows us to suggest that this diade is indispensable for caspase processing and activity. Spontaneous mutations in this diade might influence oncosuppressive function of caspases, in particular of caspase-2. Likewise, the mutation of Ser-384 is associated with the development of lung squamous cell carcinoma and adenocarcinoma. Taken together, we have uncovered a central feature of the caspase-2 activation mechanism which is crucial for the regulation of its signaling network.

Lethal and Non-Lethal Functions of Caspases in the DNA Damage Response

“…Aurora B kinase phosphorylates caspase-2 on position S384 [ 107 ], which blocks catalytic activity but not dimerization. S384 appears to be essential for the architecture of the catalytic site of caspase-2, allowing access to substrates [ 109 ]. In contrast, Cyclin B1 phosphorylates caspase-2 at S340 in the caspase-2 interdomain linker between the large and small catalytic subunit and this phosphorylation event blocks dimerization but not the recruitment of caspase-2 to its activation platform [ 108 ].…”

Caspase-2 in liver disease and hepatocellular carcinoma

“…Although dimerization and proteolytic cleavage of caspase-2 enhance caspase activity-especially for apoptotic functions-partial activation of caspase-2 upon dimerization and recruitment at activation complexes could be sufficient for caspase-2 activity in non-apoptotic functions. In addition to these cleavage site residues, Cys320 is the catalytic site and Ser384 is essential for the interactions within the caspase-2 active site [13]. Moreover, there are evidences of caspase-2 phosphorylation at a total of 11 sites in mammals (PhosphoSitePlus ® database [14]): Ser24 [15], Ser80 [15], Ser157 [15][16][17][18][19][20], Thr161 [15], Ser139 [15,21], Ser164 [15,21,22], Thr180 [15,23], Ser220 [15], Ser340 [13,15,17,18,[24][25][26][27][28][29][30], Ser346 [15], and Ser384 [15].…”

“…In addition to these cleavage site residues, Cys320 is the catalytic site and Ser384 is essential for the interactions within the caspase-2 active site [13]. Moreover, there are evidences of caspase-2 phosphorylation at a total of 11 sites in mammals (PhosphoSitePlus ® database [14]): Ser24 [15], Ser80 [15], Ser157 [15][16][17][18][19][20], Thr161 [15], Ser139 [15,21], Ser164 [15,21,22], Thr180 [15,23], Ser220 [15], Ser340 [13,15,17,18,[24][25][26][27][28][29][30], Ser346 [15], and Ser384 [15]. While specific protein kinase CK2 (PKCK2) has been reported to phosphorylate caspase-2 at Ser157 [20], calcium/calmodulin-dependent protein kinase II (CaMKII) at Ser164 [21,22], and cyclin dependent kinase 1 (CDK1) at Ser340 [31], Aurora B kinase (AURKB) appears to be able to phosphorylate each and every one of the identified caspase-2 sites [15,17].…”

Platinum drugs and taxanes: can we overcome resistance?

“…Another p53-inducible protein, which is activated by cisplatin and has a dual effect on apoptosis, is a p53-induced protein with a death domain (PIDD). This protein interacts with RIP-associated Ich-1/Ced-3 homologous protein with a death domain (RAIDD) and recruits procaspase-2 leading to truncation of Bid by active caspase-2 and following mitochondrial outer membrane permeabilization (MOMP) and apoptosis [36].…”