Volume 271, Number 36,
Issue of September 6, 1996
pp. 21870-21877
©1996 by The American Society for Biochemistry and Molecular Biology, Inc.
Domain-specific Gene Activation by Parathyroid Hormone in
Osteoblastic ROS17/2.8 Cells
(Received for publication, January 22, 1996, and in revised form, April 25, 1996)
Angela
Hollnagel
,
Dietmar
Schröder
and
Gerhard
Gross
From the Gesellschaft für Biotechnologische Forschung, Gene
Regulation and Differentiation, Mascheroder Weg 1, 38124 Braunschweig, Federal Republic of Germany
Parathyroid hormone (PTH)-mediated gene
activation was assessed in the osteoblast-like rat cell line ROS17/2.8
with two PTH fragments harboring distinct activating domains:
PTH-(1-34) and PTH-(28-48). The PTH response of genes expressed
immediate early in the cell cycle or in the osteoblast developmental
sequence was investigated. In addition, subtractive cloning was used to
identify genes in ROS17/2.8 cells that are activated by the two PTH
domains. PTH-(1-34) immediately increased the transcript levels of
c-fos and c-jun at a considerably higher rate
than PTH-(28-48). A significant immediate PTH effect on osteoblastic
marker genes could not be detected, with the exception of elevated
ornithine decarboxylase transcript levels. However, continuous
application of PTH-(1-34) increased transcript levels of the
osteoblast-specific osteocalcin gene and reduced those of other
osteoblastic marker genes including alkaline phosphatase and the
PTH/PTH-related peptide receptor. By subtractive cloning, nine
cDNAs were isolated corresponding to mRNAs directly
up-regulated by PTH-(1-34) or PTH-(28-48). Among these were a cyclic
phosphodiesterase, a (cytosine 5)-methyltransferase, an 80-kDa protein
kinase C substrate, junB, and a novel GC-binding protein.
Three cDNAs are unknown at present. Interestingly, in all cases,
the efficiency of gene activation by PTH-(28-48) was substantially
lower in comparison with PTH-(1-34). PTH-mediated protein kinase C
signaling in ROS17/2.8 cells may therefore constitute a minor pathway
in comparison with the dominant cAMP/protein kinase A cascade.