Characterization of the epithelial membrane protein 3 interaction network reveals a potential functional link to mitogenic signal transduction regulation

Abstract

Epithelial Membrane Protein 3 (EMP3), a 4‐transmembrane glycoprotein, first gained attention as a putative tumor suppressor. Accumulating evidence, however, points to a more tumor promotive function of EMP3. The biological function of EMP3 remains largely unclear. To elucidate more of EMP3’s interaction network, we performed a Yeast‐Two‐Hybrid (Y2H) screening, followed by validation of candidate interactors by Biomolecular Fluorescence Complementation (BiFC) and Proximity Ligation Assay (PLA). Furthermore, we generated stable EMP3 knockdown cell lines and measured cell proliferation, migration and sensitivity to apoptosis induction as well as the expression and activation levels of important signal pathway components. The Y2H screening yielded 10 novel interactions of EMP3, eight of which could also be detected by BiFC and PLA interaction assays. All newly discovered interaction partners are involved in signaling or trafficking regulation. Most notably, FLOT1 and HTATIP2 have well described roles in the regulation of EGFR signaling. In addition, knockdown of EMP3 resulted in reduced levels of p‐AKT, p‐ERK and p‐EGFR, attenuated cell proliferation and migration and sensitized cells to apoptosis induction by TRAIL and Staurosporine. Based on these observations we hypothesize that EMP3 might be involved in the regulation of receptor‐tyrosine‐kinase mediated mitogenic signaling.

A role for annexin A2 in scaffolding the peroxiredoxin 2–STAT3 redox relay complex

“…The gateway destination vectors pDest HA-LN151 and pDest MYC-LC151, described previously 30 , were kindly provided by Stephan Pusch (German Cancer Research Center). The ORFs for peroxiredoxin 1 and 2 and STAT3 were provided by the DKFZ Genomics & Proteomics Core Facility.…”

The Multifunctional Role of EMP3 in the Regulation of Membrane Receptors Associated with IDH-Wild-Type Glioblastoma

“…EMP3 is a 163-amino acid tetraspan membrane protein (~18 kDa) encoded by the EMP3 gene in the human chromosome 19q13.3 [ 23 , 24 , 25 ]. It belongs to the peripheral myelin protein 22-kDa (PMP22) gene family based on the sequence and structural homology [ 24 , 26 ].…”

“…The major part of EMP3 consists of four hydrophobic membrane-spanning domains spanning 21 amino acids each [ 25 , 27 ] ( Figure 2 ). There are two extracellular domains (ECD) of 41 and 18 amino acids each [ 25 , 27 ].…”

“…The major part of EMP3 consists of four hydrophobic membrane-spanning domains spanning 21 amino acids each [ 25 , 27 ] ( Figure 2 ). There are two extracellular domains (ECD) of 41 and 18 amino acids each [ 25 , 27 ]. The three intracellular domains consist of short cytoplasmic N-and C-terminal tails and a loop of 13 amino acids [ 25 , 27 ].…”

“…There are two extracellular domains (ECD) of 41 and 18 amino acids each [ 25 , 27 ]. The three intracellular domains consist of short cytoplasmic N-and C-terminal tails and a loop of 13 amino acids [ 25 , 27 ]. Its hydrophobic regions, particularly the 2nd and 4th membrane-spanning domains, are highly conserved among the PMP22 protein family [ 24 , 26 ].…”