Extracellular matrix metalloproteinase (MMP) inducer (EMMPRIN), also known as basigin and CD147, is a 44‑66 kDa, variably N‑ and O‑glycosylated, type I transmembrane protein that belongs to the immunoglobulin superfamily (1‑4). Human EMMPRIN is 269 amino acids (aa) in length and contains a 24 aa signal sequence, a 183 aa extracellular domain (ECD), a 21 aa transmembrane (TM) segment and a 41 aa cytoplasmic tail. The ECD contains one C2‑type and one V‑type Ig‑like domain. There is one 385 aa splice variant that contains an extra N‑terminal IgCAM domain and is found only in the retina (5). There are additional multiple potential isoform variants for EMMMPRIN. Two that have been characterized are 205 and 176 aa in length. The 176 aa isoform utilizes an alternative start site at Met94, while the 205 aa isoform contains an 11 aa substitution for aa 1‑75. Notably, the 176 aa isoform heterodimerizes with the standard EMMPRIN isoform and down‑modulates its activity. This is in contrast to EMMPRIN homodimers that show full biological activity (6). EMMPRIN is expressed in areas of tissue remodeling, including endometrium, placenta, skin, and regions undergoing angiogenesis (1, 2, 7‑10). It is also expressed on cells with high metabolic activity, such as lymphoblasts, macrophages and particularly tumor cells (2, 11). On such cells, EMMPRIN is often co‑expressed with the amino acid transporter CD98h (12). EMMPRIN also interacts with caveolin-1 (via its C2‑like domain), and this reduces the level of EMMPRIN glycosylation and subsequent EMMPRIN multimerization and activity (13). In addition, EMMMPRIN is reported to complex with both annexin II and beta 1
integrins alpha 3
and alpha 6
, an interaction that contributes to tumor growth and metastasis (14‑16). Finally, the soluble calcium‑binding protein S100A9 has now been identified as a ligand for EMMPRIN, and may mediate many of the tumorigenic activities attributed to EMMPRIN (17). EMMPRIN’s TM sequence contains a charged aa (Glu), and a Pro important for intracellular interactions with cyclophilins (CyP) (3, 18, 19). CyPA (cyclosporin A receptor) and CyP60 interactions with the TM segment promote leukocyte inflammatory chemotaxis and surface expression of EMMPRIN, respectively (18, 19). An active 22 kDa fragment can be shed from tumor cells by MT1‑MMP (1). Tumor cells can also release active, full‑length EMMPRIN in microvesicles (20, 21). Functionally, EMMPRIN is known to induce urokinase‑type plasminogen activator (uPA), VEGF, hyaluronan and multiple MMPs (1, 2, 8‑10). Human EMMPRIN (269 aa) shows 58%, 58%, 62% and 52% aa identity with mouse, rat, cow and chick EMMPRIN, respectively. It also shows 25% and 38% aa identity with the related proteins, embigin and neuroplastin (SDR‑1), respectively.
- Gabison, E. E. et al. (2005) Biochimie 87:361.
- Yurchenko, V. et al. (2006) Immunology 117:301.
- Kasinrerk, W. et al. (1992) J. Immunol. 149:847.
- Iacono, K.T. et al. (2007) Exp. Mol. Pathol. 83:283.
- Hanna, S. M. et al. (2003) BMC Biochem. 4:17.
- Liao, C-G. et al. (2011) Mol. Cell. Biol. 31:2591.
- Riethdorf, S. et al. (2006) Int. J. Cancer 119:1800.
- Braundmeier, A. G. et al. (2006) J. Clin. Endocrinol. Metab. 91:2358.
- Tang, Y. et al. (2006) Mol. Cancer Res. 4:371.
- Quemener, C. et al. (2007) Cancer Res. 67:9.
- Wilson, M. C. et al. (2005) J. Biol. Chem. 280:27213.
- Xu, D. and M. E. Hemler, (2005) Mol. Cell. Proteomics 4:1061.
- Tang, W. et al. (2004) Mol. Biol. Cell 15:4043.
- Zhao, P. et al. (2010) Cancer Sci. 101:387.
- Dai, J. et al. (2009) BMC Cancer 9:337.
- Li, Y. et al. (2012) J. Biol. Chem. 287:4759.
- Hibino, T. et al. (2013) Cancer Res. 73:172.
- Arora, K. et al. (2005) J. Immunol. 175:517.
- Pushkarsky, T. et al. (2005) J. Biol. Chem. 280:27866.
- Egawa, N. et al. (2006) J. Biol. Chem. 281:37576.
- Sidhu, S. S. et al. (2004) Oncogene 23:956.