Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P11021 (BiP)
 2,049 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Transient protein synthesis inhibition is an important protective mechanism used by cells during various stress conditions including endoplasmic reticulum (ER) stress. This response centers on the phosphorylation state of eukaryotic initiation factor (eIF)-2 alpha, which is induced by kinases like protein kinase R-like ER kinase (PERK) and GCN2 to suppress translation and is later reversed so translation resumes. GADD34 was recently identified as the factor that activates the type 1 protein serine/threonine phosphatase (PP1), which dephosphorylates eIF-2 alpha during cellular stresses. Our study delineates a negative feedback regulatory loop in which the eIF-2 alpha-controlled inhibition of protein translation leads to GADD34 induction, which promotes translational recovery. We show that activating transcription factor-4 (ATF4), which is paradoxically translated during the eIF-2 alpha-mediated translational block, is required for the transactivation of the GADD34 promoter in response to ER stress and amino acid deprivation. ATF4 directly binds to and trans-activates a conserved ATF site in the GADD34 promoter during ER stress. Examination of ATF4-/- MEFs revealed an absence of GADD34 induction, prolonged eIF-2 alpha phosphorylation, delayed protein synthesis recovery, and diminished translational up-regulation of BiP during ER stress. These studies demonstrate the essential role of GADD34 in the resumption of protein synthesis, define the pathway for its induction, and reveal that cytoprotective unfolded protein response targets like BiP are sensitive to the eIF-2 alpha-mediated block in translation.
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PMID:Delineation of a negative feedback regulatory loop that controls protein translation during endoplasmic reticulum stress. 1284 28

We have recently identified (a) ectocalreticulin as the main source of immunogenicity of cancer cell death induced by chemotherapy or radiotherapy, (b) ectoERP57 as critical protein for inducing cell surface exposure of calreticulin, and (c) that ectoERP57 and ectocalreticulin are cotranslocated together to the tumor cell surface by the mediator of the inhibition of PP1/GADD34 complex. Here, I report that the immunogenicity of cancer cell death induced by anticancer targeted proapoptotic peptides is also dictated by ectocalreticulin. To improve the anticancer activity of these proapoptotic peptides, I have designed several targeted chimeric inhibitor peptides of the PP1/GADD34 complex, which are comprised of an inhibitor peptide of the PP1/GADD34 complex fused to a protein transduction domain-5, to prostate homing peptide, or to the tumor antigen BiP/GRP78-binding peptide motifs. These inhibitor peptides (a) induce ectocalreticulin and ectoERP57 in a variety of tumor cell lines by the mediator of the inhibition of the interaction between PP1 and GADD34, (b) increase the phagocytosis of anticancer targeted proapoptotic peptide-treated tumor cells by dendritic cells, and (c) improve highly the anticancer activity of proapoptotic peptides and chemotherapy by suppressing or reducing the tumor growth in several isogenic mouse models of colon, mammary, and fibrosarcoma tumors and by increasing the lifespan of transgenic adenocarcinoma mouse prostate mice. These results suggest (a) that the inhibition of PP1/GADD34 complex is a key element to improve the anticancer activity of targeted proapoptotic peptides and chemotherapy and (b) that these targeted peptides combination approach could serve as a new powerful autonomous anticancer therapy.
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PMID:Anticancer activity of targeted proapoptotic peptides and chemotherapy is highly improved by targeted cell surface calreticulin-inducer peptides. 1975 16