Open AccessInteractome analysis of Bag-1 isoforms reveals novel interaction partners in endoplasmic reticulum-associated degradation
Author(s) -
Nisan Denizce Can,
Ezgi Basturk,
Tugba Kizilboga,
İzzet Mehmet Akçay,
Baran Dingiloglu,
Özge Tatlı,
Sevilay Acar,
Pelin Özfiliz Kilbaş,
Efe Elbeyli,
Serena Muratcioğlu,
Ayşe Tarbın Jannuzzi,
Attila Gürsoy,
Özlem Keskin,
Levent Doganay,
Baran Yılmaz,
Gizem Dinler Doğanay
Publication year - 2021
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0256640
Subject(s) - interactome , endoplasmic reticulum associated protein degradation , endoplasmic reticulum , microbiology and biotechnology , gene isoform , protein degradation , protein–protein interaction , biology , proteasome , proteomics , in silico , ubiquitin , calnexin , unfolded protein response , proteome , biochemistry , calreticulin , gene
Bag-1 is a multifunctional protein that regulates Hsp70 chaperone activity, apoptosis, and proliferation. The three major Bag-1 isoforms have different subcellular localizations and partly non-overlapping functions. To identify the detailed interaction network of each isoform, we utilized mass spectrometry-based proteomics and found that interactomes of Bag-1 isoforms contained many common proteins, with variations in their abundances. Bag-1 interactomes were enriched with proteins involved in protein processing and degradation pathways. Novel interaction partners included VCP/p97; a transitional ER ATPase, Rad23B; a shuttling factor for ubiquitinated proteins, proteasome components, and ER-resident proteins, suggesting a role for Bag-1 also in ER-associated protein degradation (ERAD). Bag-1 pull-down from cells and tissues from breast cancer patients validated these interactions and showed cancer-related prominence. Using in silico predictions we detected hotspot residues of Bag-1. Mutations of these residues caused loss of binding to protein quality control elements and impaired proteasomal activity in MCF-7 cells. Following CD147 glycosylation pattern, we showed that Bag-1 downregulated VCP/p97-dependent ERAD. Overall, our data extends the interaction map of Bag-1, and broadens its role in protein homeostasis. Targeting the interaction surfaces revealed in this study might be an effective strategy in the treatment of cancer.