title: Protein kinase C α regulates nuclear pri-microRNA 15a release as part of endothelin signaling.
abstract: Endothelin-1 induced signaling is characterized by an early induction of a nuclear factor-kappa B p65/mitogen-activated phosphokinase p38 transcription complex via its A-receptor versus a late induction via diacylglycerol, and protein kinase C. A possible interaction between these two pathways and a potential function for protein kinase C in this context has not previously been elucidated. Here we report that in Caki-1 tumor cells, protein kinase C α is a part of the transcription complex. With importin α4 and α5 as chaperones, the transcription complex transmigrates into the nucleus. Protein kinase C α blocks the nuclear release of pri-microRNA 15a by direct binding shown by electrophoretic mobility shift assay and Duolink immune histology. The expression levels of miRNA 15a can be further manipulated by transfection of si-protein kinase C α, or an expression vector containing protein kinase C α or miRNA 15. The miRNA 15a regulation by protein kinase C α is detectable in different malignant human tumor cell lines (renal cell carcinoma, breast carcinoma, and melanoma). Furthermore, all three cell lines harbor both endothelin receptors (ETAR/ETBR). Specific blockage of each receptor leads to major reduction of miRNA 15a expression due to increased nuclear protein kinase C α translocation. We conclude that the nuclear binding of pri-microRNA 15a is a novel function of protein kinase C α, which plays an important role in endothelin-1 mediated signaling. Since several endothelin-sensitive, malignant tumor cell lines harbor this regulation, it could indicate a more general role in tumor biology.
authors.affiliation: Institute of Pathology, University Hospital, Kerpenerstraße 62, 50924 Cologne, Germany.
authors.forename: Melanie
authors.initials: M
authors.lastname: von Brandenstein
authors.forename: Reinhard
authors.initials: R
authors.lastname: Depping
authors.forename: Ekaterine
authors.initials: E
authors.lastname: Schäfer
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Dienes
authors.forename: Jochen W U
authors.initials: JW
authors.lastname: Fries
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000187:drug effects; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism*; D016232:Endothelins / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006801:Humans; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology; D051571:Protein Kinase C-alpha / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*; D034741:RNA, Small Interfering / Q000494:pharmacology; D015398:Signal Transduction / Q000502:physiology
chemical_list: D016232:Endothelins; C505361:MIRN15 microRNA, human; D035683:MicroRNAs; D034741:RNA, Small Interfering; D051571:Protein Kinase C-alpha