|Description|| SIVA1 contains a unique amphipathic helical region (SAH) in the N-terminal region, a death domain homology region (DDHR) in the central part of the protein, and a Zinc finger-like structure at its C-terminal region. The SIVA2 isoform lacks the DDHR domain (Figure 1).|
| || Figure 1. Schematic structure of SIVA1 and SIVA2 proteins. The amphipathic helical region (SAH) at the N-terminal region, a death domain homology region (DDHR) in the central section, and a Zinc finger-like (ZF) structure at its C-terminal region are illustrated. The amino acids (aa) positions are indicated.|
|Localisation|| SIVA1 is found in the nucleus and cytoplasm (Figure 2).|
| || Figure 2. Intracellular localization of SIVA1 protein in a prostate cancer cell line. Confocal analysis of LNCaP cells displaying SIVA (green), DAPI (blue) and Actin (red) staining; MERGE shows the overlapped images. Scale bar, 10 µm. Note the cytoplasmatic and nuclear localization of SIVA1. Anti-SIVA1 (sc-7436) was from Santa Cruz Biotechnology, (Santa Cruz, CA, USA), Phalloidin (A12379) and DAPI (P-36931) were from Invitrogen (Carlsbad, CA, USA). Personal data.|
|Function|| The proapoptotic function of SIVA1 is well elucidated and characterized. SIVA1 binds to death receptors, including CD27 and TNFRSF18, and plays a role in the transduction of the proapoptotic signal by the extrinsic pathway (Prasad et al., 1997; Spinicelli et al., 2002). SIVA1 interacts with BCL2 and BCL-XL, abrogates their antiapoptotic functions and modulates the intrinsic apoptosis pathway (Chu et al., 2004; Chu et al., 2005). In addition, SIVA1 associates with XIAP and regulates the apoptosis mediated by NFkB and JNK signaling (Resch et al., 2009). The SIVA gene is a transcription target of p53, p73 and E2F1 and is upregulated under stress or following DNA damage (Ray et al., 2011; Fortin et al., 2004).|
Recently, novel partners and functions have been attributed to SIVA1. SIVA1 binds to and regulates p53 stability by acting as an adapter protein between p53 and MDM2, and participates in an auto-regulatory feedback loop between p53 and SIVA1 (Du et al., 2009; Mei and Wu, 2012). SIVA1 associates with ARF, enabling its ubiquitination and degradation; this mechanisms also regulates the p53/MDM2 signaling pathway (Wang et al., 2013).
Finally, SIVA1 is a novel adaptor protein that promotes Stathmin 1/CaMKII interaction. SIVA1 inhibits Stathmin 1 activity through Stathmin 1 phosphorylation at serine 16, which results in reduced cell migration and metastasis by stabilizing microtubules of tumor cells (Li et al., 2011). The main functions and signaling pathways of SIVA1 are illustrated in Figure 3.
The binding partners of SIVA1 are:
CD27: SIVA1 was initially identified by two-hybrid (Y2H) screening using CD27 as a bait, and its interaction was confirmed by immunoprecipitation (IP) of 293 cells co-expressing both proteins (Prasad et al., 1997). In agreement, Yoon et al. found that murine Siva1 and Siva2 also bind to CD27 (Yoon et al., 1999).
c-abl oncogene 2, non-receptor tyrosine kinase (ABL2): Y2H screening using ABL2 (previously known as ARG) as the bait identified SIVA1 as a binding partner. This protein association was confirmed by IP of MCF7 cells co-expressing FLAG-ABL2 and GFP-SIVA1 (Cao et al., 2001).
Tumor necrosis factor receptor superfamily, member 18 (TNFRSF18): TNFRSF18 (previously known as GITR) presents high homology with CD27. The interaction between TNFRSF18 and SIVA1 was identified using GST pull down and IP assays (Spinicelli et al., 2002).
BCL2-like 1 (BCL-XL): The association of BCL-XL and SIVA1 was first identified using purified GST-SIVA and BCL-XL proteins and confirmed by GST pull down assays using GST-SIVA1 in 293 cells expressing the GFP-BCL-XL protein (Xue et al., 2002). Later on, Chu et al. reported that the SAH region of SIVA1 was sufficient to specifically interact with BCL-XL (Chu et al., 2004).
B-cell CLL/lymphoma 2 (BCL2): The association of BCL2 and SIVA1 was verified using GST pull down assays with GST-SIVA in Cos-7 cells overexpressing full-length BCL2 protein, and this interaction occurred at the SAH region of SIVA1 (Chu et al., 2004).
CD4: Y2H screen using cytoplasmic domain of CD4 as the bait identified SIVA1. This protein interaction was confirmed by in vitro binding assays with GST-SIVA1. The interaction was mapped through GST pull-down assay using GST tagged deletion mutants of SIVA1; the C-terminal region of SIVA1 binds to the cytoplasmic domain of CD4 (Py et al., 2007).
Lysophosphatidic acid receptor 2 (LPAR2): Y2H screening using the C-terminal region of LPAR2 as the bait identified SIVA1. GST pull-down assays confirmed this protein association and the SIVA1 C-terminal region (aa 139-175) is required for this interaction (Lin et al., 2007).
Pyrin (MEFV): Y2H screening using Pyrin as the bait identified SIVA1 binding, and this association was confirmed by IP. Using deletion mutants of Pyrin and of SIVA1 or SIVA2, the C-terminal, rfp and SRPY domain of pyrin were found to interact with the N-terminal region of SIVA (Balci-Peynircioglu et al., 2008).
X-linked inhibitor of apoptosis (XIAP): Y2H screening using XIAP as the bait identified SIVA1 binding, and this protein association was confirmed by IP of 293 cells co-expressing both proteins (Resch et al., 2009).
FHL1 four and a half LIM domains 1 (FHL1): Y2H screening using the SLIMMER isoform of FHL1 as the bait identified SIVA; and this protein association was confirmed by IP. Three different isoforms of FHL1 were used in a Y2H assay for protein interaction mapping, SIVA1 binds only with the SLIMMER and not with FHL1 and KyoT2 isoforms (Cottle et al., 2009).
p53: The interaction between p53 and SIVA1 was tested by IP using H1229 cells co-expressing FLAG-p53 and GFP-SIVA1 and confirmed by IP using endogenous proteins from A549 cells. GST pull-down assays indicate that SIVA1 binds to p53 using its N-terminal region and DDHR, while p53 binds to SIVA1 via its DBD domain (Du et al., 2009).
Tyrosine kinase 2 (TYK2): Y2H screening using TYK2 as the bait identified SIVA1 binding, and this association was confirmed by IP of 293 cells co-expressing FLAG-SIVA1 and full-length TYK2. The SIVA1 N-terminal region binds to TYK2, as demonstrated by IP of 293T cells overexpressing GFP tagged deletion mutants of SIVA1 and FLAG-TYK2 (Shimoda et al., 2010).
Stathmin 1: Y2H screening using SIVA1 as bait identified Stathmin 1, and this association was confirmed by IP of U2OS cells co-expressing exogenous or endogenous SIVA1 and Stathmin 1 proteins (Li et al., 2011).
Cyclin-dependent kinase inhibitor 2A (CDKN2A), also known as ARF: The ARF and SIVA interaction was tested by IP assays of H1229 cells containing FLAG-SIVA1 and GFP-ARF, and purified recombinant proteins were used for confirmation. The protein interaction mapping was performed by GST pull down assays using deletion mutants of SIVA1 and ARF overexpressed in 293 cells. SIVA1 binds to ARF by its N-terminal region and DDHR, while the residue aa 21-64 of ARF is required (Wang et al., 2013).
| || Figure 3. SIVA1 signaling pathway. (1) SIVA1 binds to death receptors and modulates the extrinsic apoptosis pathway. (2) SIVA 1 binds to BCL2 proteins family, inhibits the antiapoptotic proteins, BCL2 and BCL-XL, and leads to proapoptotic BAD protein oligomerization, and modulates the intrinsic apoptosis pathway. (3) SIVA1 binds to the XIAP protein and balances the proapoptotic and antiapoptotic signaling through the JNK and NFkB pathway, respectively, and modulates the extrinsic apoptosis pathway. (4) SIVA1 promotes Stathmin 1/CaMKII interaction, Stathmin 1 phosphorylation and inhibition, and modulates microtubule dynamics. (5) The SIVA1 gene is a transcription target of p53, p73 and E2F1. (6) SIVA1 protein acts as an adapter protein between p53 and MDM2, and promotes p53 ubiquitination. (7) SIVA1 acts as an ARF E3 ubiquitin ligase and regulates cell proliferation by the ARF/p53/MDM2 pathway. Abbreviations: P, phosphorylation; Ac, acetylation; Ub, ubiquitination. Figure was produced using Servier Medical Art.|
|Homology|| SIVA1 shares high homology (around 40%) in its DDHR domain with the FADD and RIP proteins. SIVA1 also shares a high homology with different species (Table 1).|
| Pyrin, product of the MEFV locus, interacts with the proapoptotic protein, Siva.|
| Balci-Peynircioglu B, Waite AL, Hu C, Richards N, Staubach-Grosse A, Yilmaz E, Gumucio DL.|
| J Cell Physiol. 2008 Sep;216(3):595-602. doi: 10.1002/jcp.21435.|
| The p53-induced Siva-1 plays a significant role in cisplatin-mediated apoptosis.|
| Barkinge JL, Gudi R, Sarah H, Chu F, Borthakur A, Prabhakar BS, Prasad KV.|
| J Carcinog. 2009;8:2.|
| The ARG tyrosine kinase interacts with Siva-1 in the apoptotic response to oxidative stress.|
| Cao C, Ren X, Kharbanda S, Koleske AJ, Prasad KV, Kufe D.|
| J Biol Chem. 2001 Apr 13;276(15):11465-8. Epub 2001 Feb 23.|
| Expression of Siva-1 protein or its putative amphipathic helical region enhances cisplatin-induced apoptosis in breast cancer cells: effect of elevated levels of BCL-2.|
| Chu F, Barkinge J, Hawkins S, Gudi R, Salgia R, Kanteti PV.|
| Cancer Res. 2005 Jun 15;65(12):5301-9.|
| The Siva-1 putative amphipathic helical region (SAH) is sufficient to bind to BCL-XL and sensitize cells to UV radiation induced apoptosis.|
| Chu F, Borthakur A, Sun X, Barkinge J, Gudi R, Hawkins S, Prasad KV.|
| Apoptosis. 2004 Jan;9(1):83-95.|
| SLIMMER (FHL1B/KyoT3) interacts with the proapoptotic protein Siva-1 (CD27BP) and delays skeletal myoblast apoptosis.|
| Cottle DL, McGrath MJ, Wilding BR, Cowling BS, Kane JM, D'Arcy CE, Holdsworth M, Hatzinisiriou I, Prescott M, Brown S, Mitchell CA.|
| J Biol Chem. 2009 Sep 25;284(39):26964-77. doi: 10.1074/jbc.M109.036293. Epub 2009 Jul 29.|
| Suppression of p53 activity by Siva1.|
| Du W, Jiang P, Li N, Mei Y, Wang X, Wen L, Yang X, Wu M.|
| Cell Death Differ. 2009 Nov;16(11):1493-504. doi: 10.1038/cdd.2009.89. Epub 2009 Jul 10.|
| The proapoptotic gene SIVA is a direct transcriptional target for the tumor suppressors p53 and E2F1.|
| Fortin A, MacLaurin JG, Arbour N, Cregan SP, Kushwaha N, Callaghan SM, Park DS, Albert PR, Slack RS.|
| J Biol Chem. 2004 Jul 2;279(27):28706-14. Epub 2004 Apr 22.|
| Siva1 suppresses epithelial-mesenchymal transition and metastasis of tumor cells by inhibiting stathmin and stabilizing microtubules.|
| Li N, Jiang P, Du W, Wu Z, Li C, Qiao M, Yang X, Wu M.|
| Proc Natl Acad Sci U S A. 2011 Aug 2;108(31):12851-6. doi: 10.1073/pnas.1017372108. Epub 2011 Jul 18.|
| The lysophosphatidic acid 2 receptor mediates down-regulation of Siva-1 to promote cell survival.|
| Lin FT, Lai YJ, Makarova N, Tigyi G, Lin WC.|
| J Biol Chem. 2007 Dec 28;282(52):37759-69. Epub 2007 Oct 26.|
| Differentially expressed genes in activin-induced apoptotic LNCaP cells.|
| Lin S, Ying SY.|
| Biochem Biophys Res Commun. 1999 Apr 2;257(1):187-92.|
| Multifaceted functions of Siva-1: more than an Indian God of Destruction.|
| Mei Y, Wu M.|
| Protein Cell. 2012 Feb;3(2):117-22. doi: 10.1007/s13238-012-2018-5. Epub 2012 Mar 17. (REVIEW)|
| Gene expression analysis in colorectal cancer using practical DNA array filter.|
| Okuno K, Yasutomi M, Nishimura N, Arakawa T, Shiomi M, Hida J, Ueda K, Minami K.|
| Dis Colon Rectum. 2001 Feb;44(2):295-9.|
| CD27, a member of the tumor necrosis factor receptor family, induces apoptosis and binds to Siva, a proapoptotic protein.|
| Prasad KV, Ao Z, Yoon Y, Wu MX, Rizk M, Jacquot S, Schlossman SF.|
| Proc Natl Acad Sci U S A. 1997 Jun 10;94(12):6346-51.|
| The Siva protein is a novel intracellular ligand of the CD4 receptor that promotes HIV-1 envelope-induced apoptosis in T-lymphoid cells.|
| Py B, Bouchet J, Jacquot G, Sol-Foulon N, Basmaciogullari S, Schwartz O, Biard-Piechaczyk M, Benichou S.|
| Apoptosis. 2007 Oct;12(10):1879-92.|
| Siva-1 and an alternative splice form lacking the death domain, Siva-2, similarly induce apoptosis in T lymphocytes via a caspase-dependent mitochondrial pathway.|
| Py B, Slomianny C, Auberger P, Petit PX, Benichou S.|
| J Immunol. 2004 Apr 1;172(7):4008-17.|
| Mdm2 inhibition induces apoptosis in p53 deficient human colon cancer cells by activating p73- and E2F1-mediated expression of PUMA and Siva-1.|
| Ray RM, Bhattacharya S, Johnson LR.|
| Apoptosis. 2011 Jan;16(1):35-44. doi: 10.1007/s10495-010-0538-0.|
| Siva1 is a XIAP-interacting protein that balances NFkappaB and JNK signalling to promote apoptosis.|
| Resch U, Schichl YM, Winsauer G, Gudi R, Prasad K, de Martin R.|
| J Cell Sci. 2009 Aug 1;122(Pt 15):2651-61. doi: 10.1242/jcs.049940. Epub 2009 Jul 7.|
| Tyrosine kinase 2 interacts with the proapoptotic protein Siva-1 and augments its apoptotic functions.|
| Shimoda HK, Shide K, Kameda T, Matsunaga T, Shimoda K.|
| Biochem Biophys Res Commun. 2010 Sep 17;400(2):252-7. doi: 10.1016/j.bbrc.2010.08.051. Epub 2010 Aug 19.|
| GITR interacts with the pro-apoptotic protein Siva and induces apoptosis.|
| Spinicelli S, Nocentini G, Ronchetti S, Krausz LT, Bianchini R, Riccardi C.|
| Cell Death Differ. 2002 Dec;9(12):1382-4.|
| Siva1 inhibits p53 function by acting as an ARF E3 ubiquitin ligase.|
| Wang X, Zha M, Zhao X, Jiang P, Du W, Tam AY, Mei Y, Wu M.|
| Nat Commun. 2013;4:1551. doi: 10.1038/ncomms2533.|
| Siva-1 binds to and inhibits BCL-X(L)-mediated protection against UV radiation-induced apoptosis.|
| Xue L, Chu F, Cheng Y, Sun X, Borthakur A, Ramarao M, Pandey P, Wu M, Schlossman SF, Prasad KV.|
| Proc Natl Acad Sci U S A. 2002 May 14;99(10):6925-30.|
| Murine Siva-1 and Siva-2, alternate splice forms of the mouse Siva gene, both bind to CD27 but differentially transduce apoptosis.|
| Yoon Y, Ao Z, Cheng Y, Schlossman SF, Prasad KV.|
| Oncogene. 1999 Nov 25;18(50):7174-9.|