AJP - Endocrinology and Metabolism, Vol 265, Issue 3 E367-E373, Copyright © 1993 by American Physiological Society
Second messenger signaling of PTH- and PTHRP-stimulated osteoclast-like cell formation from hemopoietic blast cells
T. Sugimoto, M. Kanatani, H. Kaji, T. Yamaguchi, M. Fukase and K. Chihara
Department of Medicine, Kobe University School of Medicine, Japan.
The second messenger signaling mechanisms of parathyroid hormone (PTH)- and
PTH-related peptide (PTHRP)-stimulated osteoclast-like cell formation were
investigated in mouse hemopoietic blast cells that possessed PTH binding
sites. Human (h) PTH-(1-34) or hPTHRP-(1-34) resulted in a dose-dependent
stimulation of tartrate-resistant acid phosphatase-positive multinucleated
cells (MNC) formation. Pretreatment with [Nle8,18Tyr34]hPTH-(3-34)
significantly blocked hPTH-(1-34)- and hPTHRP-(1-34)-stimulated MNC
formation. Dibutyryladenosine 3',5'-cyclic monophosphate (10(-4) M) and
forskolin (10(-5) M) as well as the stimulatory diastereoisomer of
adenosine 3',5'-cyclic phosphorothioate (Sp-cAMPS), a direct activator of
adenosine 3',5'-cyclic monophosphate (cAMP)-dependent protein kinase (PKA)
(10(-4) M), stimulated MNC formation, and Rp-cAMPS, an inhibitor of PKA
activation (10(-4) M), almost completely inhibited MNC formation stimulated
by the aforementioned agents but not by 1,25-dihydroxyvitamin D3. Moreover,
Rp-cAMPS significantly blocked PTH- and PTHRP-stimulated MNC formation.
Treatment with calcium ionophores (10(-8) and 10(-7) M) and phorbol
12-myristate 13-acetate, a protein kinase C (PKC) activator (10(-8) to
10(-6) M), but not 4 alpha-phorbol 12,13-didecanoate, a phorbol incapable
of activating PKC, stimulated MNC formation. Two PKC inhibitors
[1-(5-isoquinolinylsulfonyl)-2-methylpiperazine dihydrochloride and
staurosporine] equally blocked PTH- and PTHRP-stimulated MNC formation. The
combined pretreatment with Rp-cAMPS and PKC inhibitors completely blocked
PTH- and PTHRP-stimulated MNC formation. Present findings indicate that the
activation of PKA and PKC is directly linked to PTH- and PTHRP-stimulated
osteoclast-like cell formation from hemopoietic blast cells.
