Atlas of Genetics and Cytogenetics

in Oncology and Haematology

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Gene Section Short Communication

MED28 (mediator complex subunit 28) Ming-Fen Lee, Chun-Yin Huang Department of Nutrition and Health Sciences, Chang Jung Christian University, 396 Sec 1 Changrong Rd, Gueiren Dist, Tainan, Taiwan 71101, China (MFL), Department of Nutrition, China Medical University, 91 Hsueh-Shih Road, Taichung, Taiwan 40402, China (CYH)

Published in Atlas Database: July 2012 Online updated version : http://AtlasGeneticsOncology.org/Genes/MED28ID50131ch4p15.html DOI: 10.4267/2042/48468 This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 2.0 France Licence. © 2013 Atlas of Genetics and Cytogenetics in Oncology and Haematology

MED28 was also identified as a merlin-interacting Identity protein by yeast two-hybrid screen (Wiederhold et al., Other names: 1500003D12Rik, EG1, magicin 2004), where merlin, the neurofibromatosis 2 (NF2) HGNC (Hugo): MED28 tumor suppressor protein, belongs to the ezrin-radixin- Location: 4p15.32 moesin (ERM) family members. Affinity-binding assays demonstrated that MED28 interacted with the DNA/RNA SH3 domains of Grb2 (Wiederhold et al., 2004). Accordingly, MED28 was also named as magicin, Note merlin and Grb2 interacting cytoskeletal protein MED28 mRNA is identical to AF317679, AF358829, (Wiederhold et al., 2004). and AF321617 with the respective size of ~1, ~1.3, and In addition, several Src family members, including Src, ~3.2 kb (Wiederhold et al., 2004). They vary in the Fyn, and Lck, are also MED28-associated partners (Lee untranslated region, but share the same protein product. et al., 2006; Lu et al., 2006). Therefore, MED28/magicin/EG-1 may function as an Protein adaptor/scaffold to relay cellular signaling (Lee et al., 2006). Description Furthermore, MED28 is also found in the nucleus The full-length MED28 protein consists of 178 amino where it is presumably involved in gene transcription as acids with a predicted molecular weight ~20 kDa part of the Mediator complex (Sato et al., 2004). It is (Wiederhold et al., 2004). MED28, an evolutionaly likely that MED28 shuttles between nucleus, conserved protein, was identified as an endothelial- cytoskeleton, and cytoplasm to convey its physiological derived gene, EG-1 (Liu et al., 2002). role.

Figure 1. Diagram of pre-mRNA of MED28. The black bars are exons.

Atlas Genet Cytogenet Oncol Haematol. 2013; 17(1) 28 MED28 (mediator complex subunit 28) Lee MF, Huang CY

Figure 2. MED28 interacting proteins.

Expression mitogen-activated protein kinase kinase 1 (MAP2K1/MEK1) in MCF7 cells (Huang et al., 2012). MED28 is expressed in multiple human tissues In addition, overexpression of MED28 resulted in the (Wiederhold et al., 2004), with high expression in liver, activation of c-Src (Lu et al., 2006) and MED28 can be placenta, and testis (Liu et al., 2002). phosphorylated at Y64 by Fyn, a Src family member MED28-interacting proteins: merlin, actin, Grb2 (Lee et al., 2006). These data indicate that MED28 may (Wiederhold et al., 2004), Fyn, Lck, Src (Lee et al., function as a regulator of cellular signal transduction 2006; Lu et al., 2006), Mediator subunits (Sato et al., pathways. 2004). Cell proliferation: Localisation Ectopic overexpression of MED28 resulted in enhanced Cytoskeleton, cytoplasm, and nucleus (Sato et al., cell growth in immortal human embryonic kidney 2004; Wiederhold et al., 2004). (HEK) 293 cells, and breast cancer cell lines, MCF7 and MDA-MB-231 (Lu et al., 2005). The HEK293 Function xenograft tumor growth was also stimulated in MED28 may be involved in the regulation of numerous MED28-overexpressing cells (Lu et al., 2005). biological processes, including transcriptional Smooth muscle cell differentiation: regulation, cytoskeletal organization, signal MED28 functions a repressor of smooth muscle cell transduction, cell proliferation, differentiation, (SMC) differentiation (Beyer et al., 2007). MED28- angiogenesis, and migration (Beyer et al., 2007; Huang specific knockdown resulted in up-regulation of several et al., 2012; Liu et al., 2002; Wiederhold et al., 2004; SMC-related genes and SMC phenotype, whereas Yoon et al., 2010; Zhang et al., 2004). ectopic expression of MED28 reversed the SMC Transcription regulation: morphology induced by MED28 knockdown (Beyer et The Mediator complex is a set of protein coactivators al., 2007). that bridges DNA-binding transcription factors to Angiogenesis: transcriptional activation of the RNA polymerase II MED28 expression was increased by two-fold in (pol II). MED28 was identified as a subunit of the human umbilical vein endothelial cells (HUVECs) mammalian Mediator complex by the multidimensional treated with either tumor conditioned media or specific protein identification technology (MudPIT) (Sato et al., angiogenic factors (Liu et al., 2002). This observation 2004). This identification indicates a role of MED28 in suggests a role of MED28 in angiogenesis. the regulation of gene transcription. Cell migration: Cytoskeletal organization: The role of MED28 in cell migration was demonstrated The implication of MED28 in cytoskeletal re- in both estrogen receptor (ER)-positive and negative organization was based on the observation that human breast cancer cell lines (Huang et al., 2012; Lee MED28, similar to merlin, co-localizes with the actin et al., 2011). cytoskeleton as determined by cofractionation, Ectopic expression of MED28 increased cell migration immunofluorescence and electron microscopy and invasion in MCF7 and MDA-MB-231 breast (Wiederhold et al., 2004). cancer cells (Huang et al., 2012; Lee et al., 2011). Signal transduction: Investigation of the underlying mechanisms revealed Ectopic expression of MED28 led to increased that MED28 activates epidermal growth factor (EGF)- phosphorylation of mitogen-activated protein kinases stimulated migration through induction of matrix (MAPK) (Lu et al., 2005). In contrast, MED28-specific metalloproteinase 9 (MMP9) in EGFR-overexpressing knockdown resulted in decreased expression of MDA-MB-231 cells (Lee et al., 2011).

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Figure 3. Biological functions of MED28.

In addition, MED28 can also regulate cell migration Prognosis through the mitogen-activated protein kinase kinase 1 The evidence supporting MED28 as a prognostic factor (MAP2K1; MEK1)-dependent MMP2 activation, is emerging. MED28 peptide was detectable in serum which is independent of EGF stimulation (Huang et al., and urine of a small set of breast cancer patients (Lu et 2012). These lines of evidence support the role of al., 2007). In addition, statistical analysis on the MED28 in cell migration, implying that MED28 might correlation between MED28 and survival time or time- be responsible for cancer metastasis. to-relapse indicates that MED28 is a significant Homology predictor of malignant breast cancer (Yoon et al., 2010). MED28 has significant homology to a mouse cDNA (94%), fish, and a fly cDNA (31%) (Liu et al., 2002; References Wiederhold et al., 2004). The mouse MED28 gene is located on chromosome 5 (45520229..45529284). Liu C, Zhang L, Shao ZM, Beatty P, Sartippour M, Lane TF, Barsky SH, Livingston E, Nguyen M. Identification of a novel endothelial-derived gene EG-1. Biochem Biophys Res Implicated in Commun. 2002 Jan 11;290(1):602-12 Various cancers Sato S, Tomomori-Sato C, Parmely TJ, Florens L, Zybailov B, Swanson SK, Banks CA, Jin J, Cai Y, Washburn MP, Conaway Note JW, Conaway RC. A set of consensus mammalian mediator MED28 expression is elevated in cancers including subunits identified by multidimensional protein identification breast, colorectal, and prostate cancers, suggesting a technology. Mol Cell. 2004 Jun 4;14(5):685-91 role of MED28 in malignant phenotype of epithelial- Wiederhold T, Lee MF, James M, Neujahr R, Smith N, Murthy derived cancers (Liu et al., 2002; Zhang et al., 2004). A, Hartwig J, Gusella JF, Ramesh V. Magicin, a novel cytoskeletal protein associates with the NF2 tumor suppressor Further tissue microarray (TMA) analysis on a set of merlin and Grb2. Oncogene. 2004 Nov 18;23(54):8815-25 breast cancer population also showed elevated MED28 expression in the ductal carcinoma in situ (DCIS) and Zhang L, Maul RS, Rao J, Apple S, Seligson D, Sartippour M, Rubio R, Brooks MN. Expression pattern of the novel gene invasive ductal carcinoma lesions (Yoon et al., 2010). EG-1 in cancer. Clin Cancer Res. 2004 May 15;10(10):3504-8 Such elevated MED28 expression independently Lu M, Zhang L, Maul RS, Sartippour MR, Norris A, Whitelegge predicts poor survival (Yoon et al., 2010). These data J, Rao JY, Brooks MN. The novel gene EG-1 stimulates indicate that MED28 may be a potential therapeutic cellular proliferation. Cancer Res. 2005 Jul 15;65(14):6159-66 target in cancer intervention. Indeed, MED28 Lee MF, Beauchamp RL, Beyer KS, Gusella JF, Ramesh V. suppression via either siRNA lentivirus or polyclonal Magicin associates with the Src-family kinases and is antibody resulted in decreased growth of both MCF7 phosphorylated upon CD3 stimulation. Biochem Biophys Res and MDA-MB-231 cell lines and their corresponding Commun. 2006 Sep 29;348(3):826-31 xenograft tumors in mice (Lu et al., 2007). Lu M, Zhang L, Sartippour MR, Norris AJ, Brooks MN. EG-1 Furthermore, the in vitro application of phytochemical interacts with c-Src and activates its signaling pathway. Int J resveratrol potently inhibited EGF-stimulated cell Oncol. 2006 Oct;29(4):1013-8 migration via suppression of MED28 in MDA-MB-231 Beyer KS, Beauchamp RL, Lee MF, Gusella JF, Näär AM, breast cancer cells (Lee et al., 2011). Ramesh V. Mediator subunit MED28 (Magicin) is a repressor

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of smooth muscle cell differentiation. J Biol Chem. 2007 Nov epidermal growth factor (EGF)-induced migration in MDA-MB- 2;282(44):32152-7 231 human breast cancer cells. J Agric Food Chem. 2011 Nov 9;59(21):11853-61 Lu M, Sartippour MR, Zhang L, Norris AJ, Brooks MN. Targeted inhibition of EG-1 blocks breast tumor growth. Huang CY, Chou YH, Hsieh NT, Chen HH, Lee MF. MED28 Cancer Biol Ther. 2007 Jun;6(6):936-41 regulates MEK1-dependent cellular migration in human breast cancer cells. J Cell Physiol. 2012 Dec;227(12):3820-7 Yoon NK, Maresh EL, Elshimali Y, Li A, Horvath S, Seligson DB, Chia D, Goodglick L. Elevated MED28 expression predicts This article should be referenced as such: poor outcome in women with breast cancer. BMC Cancer. 2010 Jun 28;10:335 Lee MF, Huang CY. MED28 (mediator complex subunit 28). Atlas Genet Cytogenet Oncol Haematol. 2013; 17(1):28-31. Lee MF, Pan MH, Chiou YS, Cheng AC, Huang H. Resveratrol modulates MED28 (Magicin/EG-1) expression and inhibits

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