title: Bcl10 crucially nucleates the pro-apoptotic complexes comprising PDK1, PKCζ and caspase-3 at the nuclear envelope of etoposide-treated human cervical carcinoma C4-I cells.
abstract: Protein kinase (PK)Cζ signaling at various subcellular levels affects cell survival, differentiation, growth and/or apoptosis. However, the mechanisms modulating PKCζ activity at the nuclear membrane (NM) are not yet fully understood. Previously, we demonstrated that PKCζ interacts with the B‑cell lymphoma 10 (Bcl10) protein at the NM of human cervical carcinoma (HCC) C4‑I cells. In the present study, we aimed to further clarify the interactions between PKCζ, Bcl10 and other proteins co-immunoprecipitated from NMs isolated from untreated and etoposide (also known as VP‑16; 2.0 µg/ml)‑treated C4‑I cells using biochemical and proteomics analyses. Aside from the Bcl10 protein, 3‑phosphoinositide‑dependent protein kinase‑1 (PDK1) also co-immunoprecipitated with PKCζ from NMs of C4‑I cells, indicating the assembly of a heterotrimeric complex, which increased with time in VP‑16‑exposed cells, as did the activity of PDK1‑phosphorylated‑PKCζ. In turn, PKCζ‑phosphorylated‑Bcl10 straddled an enlarged complex which comprised caspase‑3. Subsequently, activity‑enhanced caspase‑3 cleaved and inactivated PKCζ. Finally, the suppression of Bcl10 using specific siRNA or lentiviral transduction prevented the increase in the PDK1•PKCζ association, the increase in the activity of PKCζ and caspase‑3, as well as the caspase‑3‑mediated PKCζ proteolysis and inactivation from occurring at the NMs of the VP‑16‑exposed C4‑I cells. Our observations provide evidence that Bcl10 acts as a pivotal pro-apoptotic protein which crucially nucleates complexes comprising PDK1, PKCζ and active caspase‑3 at the NMs of VP‑16‑exposed C4‑I cells. Hence, our data suggest that Bcl10 and PKCζ are potential therapeutic targets in the treatment of HCC.
authors.affiliation: Histology and Embryology Section, Department of Life and Reproduction Sciences, University of Verona Medical School, I‑37134 Verona, Venetia, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Chiarini
authors.affiliation: Chongqing Key Laboratory for Disease Proteomics, Institute of Burn Research, Southwest Hospital, Third Military Medical University, Chongqing 400038, P.R. China.
authors.forename: Daisong
authors.initials: D
authors.lastname: Liu
authors.affiliation: Histology and Embryology Section, Department of Life and Reproduction Sciences, University of Verona Medical School, I‑37134 Verona, Venetia, Italy.
authors.forename: Ubaldo
authors.initials: U
authors.lastname: Armato
authors.affiliation: Histology and Embryology Section, Department of Life and Reproduction Sciences, University of Verona Medical School, I‑37134 Verona, Venetia, Italy.
authors.forename: Ilaria
authors.initials: I
authors.lastname: Dal Prà
mesh_terms: D064413:3-Phosphoinositide-Dependent Protein Kinases / Q000378:metabolism*; D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D000074018:B-Cell CLL-Lymphoma 10 Protein; D053148:Caspase 3 / Q000378:metabolism; D045744:Cell Line, Tumor; D002584:Cervix Uteri / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D005047:Etoposide / Q000494:pharmacology*; D005260:Female; D006801:Humans; D009685:Nuclear Envelope / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D011493:Protein Kinase C / Q000378:metabolism*; D002583:Uterine Cervical Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D000099221:Protein Kinase C zeta
chemical_list: D064413:3-Phosphoinositide-Dependent Protein Kinases; D048868:Adaptor Proteins, Signal Transducing; D000972:Antineoplastic Agents, Phytogenic; D000074018:B-Cell CLL-Lymphoma 10 Protein; D053148:Caspase 3; D005047:Etoposide; D011493:Protein Kinase C; D000099221:Protein Kinase C zeta; C118591:BCL10 protein, human; C578562:PDPK1 protein, human