Abstract
Presence of the pituitary adenylate cyclase-activating polypeptide (PACAP) signalling has been proved in various peripheral tissues. PACAP can activate protein kinase A (PKA) signalling via binding to pituitary adenylate cyclase-activating polypeptide type I receptor (PAC1), vasoactive intestinal polypeptide receptor (VPAC) 1 or VPAC2 receptor. Since little is known about the role of this regulatory mechanism in bone formation, we aimed to investigate the effect of PACAP on osteogenesis of UMR-106 cells. PACAP 1-38 as an agonist and PACAP 6-38 as an antagonist of PAC1 were added to the culture medium. Surprisingly, both substances enhanced protein expressions of collagen type I, osterix and alkaline phosphatase, along with higher cell proliferation rate and an augmented mineralisation. Although expression of PKA was elevated, no alterations were detected in the expression, phosphorylation and nuclear presence of CREB, but increased nuclear appearance of Runx2, the key transcription factor of osteoblast differentiation, was shown. Both PACAPs increased the expressions of bone morphogenetic proteins (BMPs) 2, 4, 6, 7 and Smad1 proteins, as well as that of Sonic hedgehog, PATCH1 and Gli1. Data of our experiments indicate that activation of PACAP pathway enhances bone formation of UMR-106 cells and PKA, BMP and Hedgehog signalling pathways became activated. We also found that PACAP 6-38 did not act as an antagonist of PACAP signalling in UMR-106 cells.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Alkaline Phosphatase / genetics
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Alkaline Phosphatase / metabolism
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Animals
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Bone Morphogenetic Proteins / genetics
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Bone Morphogenetic Proteins / metabolism
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Cell Line, Tumor
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Cell Proliferation
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Collagen Type I / genetics
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Collagen Type I / metabolism
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Core Binding Factor Alpha 1 Subunit / metabolism
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Cyclic AMP Response Element-Binding Protein / metabolism
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Cyclic AMP-Dependent Protein Kinases / genetics
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Cyclic AMP-Dependent Protein Kinases / metabolism
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Kruppel-Like Transcription Factors / genetics
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Kruppel-Like Transcription Factors / metabolism
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Osteogenesis*
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Patched Receptors
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Pituitary Adenylate Cyclase-Activating Polypeptide / pharmacology*
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Rats
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Receptors, Cell Surface / genetics
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Receptors, Cell Surface / metabolism
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Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I / agonists
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Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I / antagonists & inhibitors
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Signal Transduction*
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Smad1 Protein / genetics
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Smad1 Protein / metabolism
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Transcription Factors / genetics
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Transcription Factors / metabolism
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Zinc Finger Protein GLI1
Substances
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Bone Morphogenetic Proteins
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Collagen Type I
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Core Binding Factor Alpha 1 Subunit
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Cyclic AMP Response Element-Binding Protein
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Gli1 protein, rat
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Kruppel-Like Transcription Factors
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Patched Receptors
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Pituitary Adenylate Cyclase-Activating Polypeptide
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Receptors, Cell Surface
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Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide, Type I
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Smad1 Protein
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Sp7 protein, rat
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Transcription Factors
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Zinc Finger Protein GLI1
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Cyclic AMP-Dependent Protein Kinases
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Alkaline Phosphatase