| || Schematic diagram of DAPK2 protein structure. The 42 KDa DAPK2 protein kinase bears three domain structures. A kinase domain on its N-terminal region determines specificity and allows for homodimerization through its basic loop. It is followed by a calcium/calmodulin (CaM)-regulated Serine/Threonine binding domain, which dictates kinase catalytic activity by unblocking substrate access when bound to Ca2+/CaM. Autophosphorylation of S308 decreases DAPK2 activity. The C-terminal dimerization domain allows for homodimerization. (Kawai T et al., 1999; Inbal B et al., 2000)|
|Description|| DAPK2 encodes a 42 KDa protein kinase (Inbal B., 2000) that belongs to the serine/threonine protein family of five proapoptotic proteins with tumor suppressor activity. DAPK2 is soluble and cytosolic (Inbal B., 2000). It contains highly-conserved N-terminal kinase catalytic domain, followed by a conserved calcium/calmodulin regulatory binding domain and a C-terminal homodimerization domain encompassing the last 40 aminoacids, predicted to form two helices, which has no sequence homology to known protein sequences. |
Autophosphorylation restrains the apoptotic activity of DAPK2 kinase by controlling dimerization and calmodulin binding (Shani G et al., 2001).
DAPK2 is a monomer in its activated state and a homodimer when inhibited by autophosphorylation at Ser-308 (Shani G et al., 2001). The dimers of DAPK2 are formed through the association of two opposed catalytic domains (Patel AK et al., 2001). DAPK2 is negatively regulated by the autoinhibitory CaM-binding domain and this inhibition is removed by the binding of Ca2+/CaM (Inbal B et al., 2000). That is, DAPK2 is activated by CaM in response to Ca2+ stimuli, and regulated by a double locking mechanism. DAPK2 is dephosphorylated at Ser-308 in response to activated Fas and TNF-alpha receptors.
| || Translation (370 aa)|
|Expression|| Widespread expression. Strong expression in heart, lung and skeletal muscle, but also expressed in colon, breast, spleen tissue and leukocytes (Kawai T et al., 1999; Inbal B et al., 2000). In mouse, DAPK2 is strongly and specifically expressed in interstitial cells of the kidney cortex (Guay JA et al., 2014).|
|Localisation|| Cytoplasm (Inbal B et al., 2000), cytoplasmic vesicles, inside autophagic vesicles (Inbal B et al., 2002).|
|Function|| DAPK2 is a regulator of apoptosis, autophagy and inflammation (Geering B 2015). |
DAPK2 overexpression induces cell apoptosis in 50 to 60% (Inbal B et al., 2000). Depletion of the C-terminal tail of DAPK2 abolishes its apoptotic activity, while further truncation of the CaM-regulatory domain strongly enhances its apoptotic effect (Inbal B et al., 2000).
DAPK2 is a modulator of TRAIL signaling and TRAIL-induced apoptosis. Genetic ablation of DAPK2 causes phosphorylation of NF-KB and its transcriptional activity in several cancer cell lines, leading to the induction of several proapoptotic proteins (TNFRSF10A (DR4) and TNFRSF10B (DR5)) (Schlegel CR et al., 2014).
DAPK2 modulates MTOR activity by directly interacting and phosphorylating mTORC1. This way it suppresses mTOR activity to promote autophagy induction and autophagy levels under stress and steady-state conditions (Ber Y et al., 2015).
Expression of DAPK2 in its activated form triggers autophagy in a caspase independent way. DAPK2 mediates the formation of autophagic vesicles during apoptosis (Inbal B et al., 2002). Expression of dominant negative mutant of DAPK2 reduces autophagy (Inbal B et al., 2002).
Protein serine/threonine kinase activity
In vitro kinase assays, using myosin light chain (MLC) as substrate, have shown both MLC phosphorylation and DAPK2 autophosphorylation (Kawai T et al., 1999; Inbal B et al., 2000). DAPK2 functions in vitro as a kinase that is capable of phosphorylating itself and an external substrate (Kawai T et al., 1999; Inbal B et al., 2000).
The addition of Ca2+/CaM to in vitro kinase assays using myosin light chain (MLC) as substrate, lead to an increased amount of phosphorylated MLC, suggesting that DPK2 is regulated by binding to CaM (Kawai T et al., 1999; Inbal B et al., 2000). DPAK2 is negatively regulated by the autoinhibitory CaM-binding domain and this inhibition is removed by the binding of Ca2+/CaM (Inbal B et al., 2000).
Truncation of the CaM-regulatory region of DAPK2 enhances the apoptotic effect (Inbal B et al., 2000). Oxidative stress regulation
DAPK2 regulates oxidative stress in cancer cells by preserving mitochondrial function. Depletion of DAPK2 leads to an increased production of mitochondrial superoxide anions and increased oxidative stress (Schlegel CR et al., 2015).
DAPK2 kinase domain in important to maintain mitochondrial integrity and thus metabolism. Depletion of DPAK2 leads to metabolic alterations, decreased rate of oxidative phosphorylation and destabilized mitochondrial membrane potential (Schlegel CR et al., 2015). Membrane blebbing
Interaction of DAPK2 with ACTA1 (α-actin-1) at the plasma membrane leads to massive membrane blebbing (Geering B et al., 2015). Expression of DAPK2 in its activated form triggers membrane blebbing and this process is caspase independent (Inbal B et al., 2002). Dominant negative mutants of DAPK2 reduce membrane blebbing during the p55/TRAF1 (TNF-receptor 1)-induced apoptosis (Inbal B et al., 2002).
Interaction of DAPK2 with α-actin-1 leads to reduced cellular motility (Geering B et al., 2015).
Intracellular signaling transduction
Depletion of DAPK2 leads to the activation of classical stress-activated kinases, such as ERK, JNK and p38 (Schlegel CR et al., 2015).
Positive regulation of eosinophil and neutrophil chemotaxis, and granulocyte maturation
DPAK2 inhibition blocks recruitment of neutrophils to the site of inflammation in a peritonitis mouse model. DAPK2 functions in a signaling pathway that mediates motility in neutrophils and eosinophils in response to intermediary chemoattractants, but not to end-target chemoattractants (Geering B et al., 2014).
DPAK2 regulates granulocytic motility by controlling cell spreading and polarization (Geering B et al., 2014) and may play a role in granulocyte maturation (Rizzi M et al., 2007).
Regulation of erythropoiesis
Among hematopoietic lineages, DPAK2 is expressed predominantly in erythroid cells. DPAK2 is substantially up-modulated during late erythropoiesis (Fang J et al., 2008). In UT7epo cells, siRNA knock-down of DAPK2 enhanced survival due to cytokine withdrawal, and DAPK2's phosphorylation and kinase activity also were erythropoietin (EPO)-modulated. DAPK2 therefore comprises a new candidate attenuator of stress erythropoiesis (Fang J et al., 2008).
The physiological substrate of DAPK2 is unknown although it is known to phosphorylate the myosin light chain in vitro (Inbal B et al., 2000).
YWHAB (14-3-3-β) (Yuasa K et al., 2015) and α-actinin-1 are novel DAPK2 binding partners (Geering B et al., 2015). The interaction of DAPK2 with α-actinin-1 is localized to the plasma membrane, resulting in massive membrane blebbing and reduced cellular motility, whereas the interaction of DAPK2 with 14-3-3- β is localized to the cytoplasm, with no impact on blebbing, motility, or viability (Geering B et al 2015). 14-3-3- proteins inhibit DAPK2 activity and its apoptotic effects (Yuasa K et al., 2015).
DAPK2 also interacts with RAD1, MAPK1 and MLC1 (Steinmann S et al., 2015).
|Homology|| DAPK3/ZIPK/DLK (Death-related protein 1); STK17A (DRAK1/STK17B (DRAK2) (DAPK-related apoptosis inducing protein kinases 1 and 2) (Shobat G et al., 2002)|
| DAPK2 is a novel regulator of mTORC1 activity and autophagy|
| Ber Y, Shiloh R, Gilad Y, Degani N, Bialik S, Kimchi A|
| Cell Death Differ 2015 Mar;22(3):465-75|
| Attenuation of EPO-dependent erythroblast formation by death-associated protein kinase-2|
| Fang J, Menon M, Zhang D, Torbett B, Oxburgh L, Tschan M, Houde E, Wojchowski DM|
| Blood 2008 Aug 1;112(3):886-90|
| Death-associated protein kinase 2: Regulator of apoptosis, autophagy and inflammation|
| Geering B|
| Int J Biochem Cell Biol 2015 Aug;65:151-4|
| DAPK2 positively regulates motility of neutrophils and eosinophils in response to intermediary chemoattractants|
| Geering B, Stoeckle C, Rozman S, Oberson K, Benarafa C, Simon HU|
| J Leukoc Biol 2014 Feb;95(2):293-303|
| Identification of Novel Death-Associated Protein Kinase 2 Interaction Partners by Proteomic Screening Coupled with Bimolecular Fluorescence Complementation|
| Geering B, Zokouri Z, HĂĽrlemann S, Gerrits B, AuslĂ¤nder D, Britschgi A, Tschan MP, Simon HU, Fussenegger M|
| Mol Cell Biol 2015 Oct 19;36(1):132-43|
| Death associated protein kinase 2 is expressed in cortical interstitial cells of the mouse kidney|
| Guay JA, Wojchowski DM, Fang J, Oxburgh L|
| BMC Res Notes 2014 Jun 7;7:345|
| The tumor suppressor gene DAPK2 is induced by the myeloid transcription factors PU|
| Humbert M, Federzoni EA, Britschgi A, SchlĂ¤fli AM, Valk PJ, Kaufmann T, Haferlach T, Behre G, Simon HU, Torbett BE, Fey MF, Tschan MP|
| 1 and C/EBPÎ± during granulocytic differentiation but repressed by PML-RARÎ± in APL J Leukoc Biol|
| DAP kinase and DRP-1 mediate membrane blebbing and the formation of autophagic vesicles during programmed cell death|
| Inbal B, Bialik S, Sabanay I, Shani G, Kimchi A|
| J Cell Biol 2002 Apr 29;157(3):455-68|
| Death-associated protein kinase-related protein 1, a novel serine/threonine kinase involved in apoptosis|
| Inbal B, Shani G, Cohen O, Kissil JL, Kimchi A|
| Mol Cell Biol 2000 Feb;20(3):1044-54|
| Death-associated protein kinase 2 is a new calcium/calmodulin-dependent protein kinase that signals apoptosis through its catalytic activity|
| Kawai T, Nomura F, Hoshino K, Copeland NG, Gilbert DJ, Jenkins NA, Akira S|
| Oncogene 1999 Jun 10;18(23):3471-80|
| Structure of the dimeric autoinhibited conformation of DAPK2, a pro-apoptotic protein kinase|
| Patel AK, Yadav RP, Majava V, Kursula I, Kursula P|
| J Mol Biol 2011 Jun 10;409(3):369-83|
| The death-associated protein kinase 2 is up-regulated during normal myeloid differentiation and enhances neutrophil maturation in myeloid leukemic cells|
| Rizzi M, Tschan MP, Britschgi C, Britschgi A, HĂĽgli B, Grob TJ, Leupin N, Mueller BU, Simon HU, Ziemiecki A, Torbett BE, Fey MF, Tobler A|
| J Leukoc Biol 2007 Jun;81(6):1599-608|
| DAPK2 regulates oxidative stress in cancer cells by preserving mitochondrial function|
| Schlegel CR, Georgiou ML, Misterek MB, StĂ¶cker S, Chater ER, Munro CE, Pardo OE, Seckl MJ, Costa-Pereira AP|
| Cell Death Dis 2015 Mar 5;6:e1671|
| Autophosphorylation restrains the apoptotic activity of DRP-1 kinase by controlling dimerization and calmodulin binding|
| Shani G, Henis-Korenblit S, Jona G, Gileadi O, Eisenstein M, Ziv T, Admon A, Kimchi A|
| EMBO J 2001 Mar 1;20(5):1099-113|
| The DAP-kinase family of proteins: study of a novel group of calcium-regulated death-promoting kinases|
| Shohat G, Shani G, Eisenstein M, Kimchi A|
| Biochim Biophys Acta 2002 Nov 4;1600(1-2):45-50|
| DAPK2 Downregulation Associates With Attenuated Adipocyte Autophagic Clearance in Human Obesity|
| Soussi H, Reggio S, Alili R, Prado C, Mutel S, Pini M, Rouault C, ClĂ©ment K, Dugail I|
| Diabetes 2015 Oct;64(10):3452-63|
| Death-associated protein kinase: A molecule with functional antagonistic duality and a potential role in inflammatory bowel disease (Review)|
| Steinmann S, Scheibe K, Erlenbach-Wuensch K, Neufert C, Schneider-Stock R|
| Int J Oncol 2015 Jul;47(1):5-15|
| miR-520h is crucial for DAPK2 regulation and breast cancer progression|
| Su CM, Wang MY, Hong CC, Chen HA, Su YH, Wu CH, Huang MT, Chang YW, Jiang SS, Sung SY, Chang JY, Chen LT, Chen PS, Su JL|
| Oncogene 2016 Mar 3;35(9):1134-42|
| Targeted restoration of down-regulated DAPK2 tumor suppressor activity induces apoptosis in Hodgkin lymphoma cells|
| Tur MK, Neef I, Jost E, Galm O, JĂ¤ger G, StĂ¶cker M, Ribbert M, Osieka R, Klinge U, Barth S|
| J Immunother 2009 Jun;32(5):431-41|
| Suppression of death-associated protein kinase 2 by interaction with 14-3-3 proteins|
| Yuasa K, Ota R, Matsuda S, Isshiki K, Inoue M, Tsuji A|
| Biochem Biophys Res Commun 2015 Aug 14;464(1):70-5|