PKD1, PKD2, and their substrate Kidins220 regulate neurotensin secretion in the BON human endocrine cell line.
Neurotensin (NT) is a gut peptide that plays an important role in gastrointestinal secretion, motility, and growth as well as the proliferation of NT receptor-positive cancers. Protein kinase D (PKD) family members (PKD1, 2, and 3) have been identified as important regulators of secretory transport at the trans-Golgi network. Previously, we showed that PKD1 contributes to stimulated NT secretion; however, the mechanisms are not entirely clear. Here, we show that Kidins220, which is a substrate of PKD proteins in neuroendocrine cells, is localized in the ends of the processes of BON cells, similar to the expression pattern of NT vesicles, and translocates to the membrane and large vesicle-like structures formed in response to phorbol 12-myristate 13-acetate treatment. The short hairpin RNA targeting Kidins220 inhibits NT secretion in parental BON cells or BON cells stably expressing the gastrin-releasing peptide receptor treated with either phorbol 12-myristate 13-acetate or bombesin, respectively. Furthermore, we demonstrate that endogenous PKD1, PKD2, and Kidins220 co-exist with NT-containing vesicles. Overexpression of the kinase-dead PKD1 abrogates Kidins220 expression and NT vesicle formation. Our data establish a physiological link between the PKD/Kidins220 pathway and NT-containing vesicles and suggest the role of this pathway in the regulation of hormone secretion. Because NT is an important gut hormone that affects secretion, inflammation, and both normal and tumor cell growth, our findings identify a novel signaling pathway that may be amenable to drug targeting for clinical applications.
Department of Surgery and Sealy Center for Cancer Cell Biology, The University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555, USA.
Jing
J
Li
L Andy
LA
Chen
Courtney M
CM
Townsend
B Mark
BM
Evers
D002460:Cell Line; D019858:Enteroendocrine Cells / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009496:Neurotensin / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D022142:Secretory Vesicles / Q000378:metabolism; D015398:Signal Transduction; D013347:Subcellular Fractions / Q000378:metabolism; D050396:TRPP Cation Channels / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D009496:Neurotensin; D011994:Recombinant Proteins; D050396:TRPP Cation Channels; D013755:Tetradecanoylphorbol Acetate; C482591:KIDINS220 protein, human