Areas of Interest
1. Regulation and function of cyclooxygenase-2 (COX-2, also
called prostaglandin G/H synthase-2 or PGHS-2) in bone. COX-2 is
an early response gene that is responsible for most
prostaglandin regulation in bone. Specific studies ongoing in
our lab include examination of transcriptional regulation of
COX-2 in osteoblastic MC3T3-E1 cells and in COX-2 promoter-luciferase
reporter transgenic mice and examination of the effects of COX-2
gene disruption on bone resorption and formation. We are
particularly interested in the role of COX-2 in osteoblast
proliferation and apoptosis.
2. Role of COX-2 in the osteoblastic response to mechanical
loading. COX-2 may mediate effects of mechanical loading on
bone. We are studying fluid shear stress induction of COX-2
expression--signaling pathways and transactivating factors
involved. We are developing in vivo models of loading and
unloading of bone and are making mice with the COX-2 promoter
fused to GFP to permit localization of cells in which loading
upregulates COX-2 transcription.
Lab Rotation Projects
Our lab studies bone biology with specific interest in the
role of cyclooxygenase-2 (COX-2) in bone formation and
resorption, regulation of bone resorption and formation by
mechanical loading, and role of COX-2 in cancer. Models range
from cell cultures to transgenic mice. Possible student projects
include the following:
1. Regulation of COX-2 by mechanical loading (modeled
by fluid shear stress) in osteoblasts (bone-forming cells) or in
ulnae of mice loaded in vivo. Studies include gene expression,
signaling pathways, transcriptional regulation and regulation of
the 3'-UTR of COX-2.
2. Regulation of the interstitial collagenase, MMP-13,
promoter by mechanical loading (fluid shear stress) in
osteoblasts. This study would require making MMP-13 promoter -
luciferase reporter (or GFP reporter) constructs.
3. Examination of one or more early response genes
identified by microarray analysis (approximately 20 genes out of
more than 12,000 genes) as upregulated by 5 min of FSS applied
to osteoblasts. Expression needs to be confirmed by Northern
and/or Western analysis. Signaling pathways involved in the
induction of expression could be examined.
4. Role of COX-2 in cell proliferation and apoptosis.
This study involve BrdU staining, 3thymidine incorporation, and
flow cytometry for cell cycle analysis. Apoptosis is measured by
flow cytometry and TUNEL staining, as well as caspase activity.
Selected Publications
Pilbeam CC, Harrison J, Raisz LG. Prostaglandins and
Leukotrienes. In "Principles of Bone Biology", J. Bilezikian, L.
Raisz, and G. Rodan, eds., Academic Press, New York, second
edition, 2002, pp 874-994.
Wadhwa S, Godwin SL, Peterson DR, Epstein MA, Pilbeam CC.
Fluid flow induction of cyclooxygenase-2 gene expression in
osteoblasts depends on the ERK signaling pathway. J Bone Miner
Res, 17:266-274,2002.
Chikazu D, Li X, Kawaguch H, Hoshi K, Voznesensky OS,
Herschman HR, Raisz LG, Pilbeam CC. Bone morphogenetic protein-2
induces cyclooxygenase-2 in osteoblasts via Cbfa1: role in
osteoblast and osteoclast differentiation. J Bone Miner Res
17:1430-1440,2002.
Wadhwa S, Choudhary S, Voznesensky M, Epstein M, Raisz L,
Pilbeam C. Fluid flow induces COX-2 expression in MC3T3-E1
osteoblasts via a PKA signaling pathway. Biochem Biophys Res
Commun 297:46-51,2002.
Okada Y, Lorenzo JA, Freeman AM, Tomita M, Morham SG, Raisz
LG, Pilbeam CC. Prostaglandin G/H synthase-2 is required for
maximal stimulation of osteoclast-like cell formation in murine
marrow and spleen cultures. J Clin Invest 105:823-832,2000.
Okada Y, Voznesensky O, Herschman H, Harrison, Pilbeam C.
Identification of multiple cis-acting elements mediating the
induction of prostaglandin G/H synthase-2 by phorbol ester in
murine osteoblastic cells. J Cell Biochem 78:197-209,2000.
Li X, Okada Y, Pilbeam CC, Lorenzo JA, Kennedy CRJ, Breyer RM,
Raisz LG. Knockout of the murine prostaglandin EP2 receptor
impairs osteoclastogenesis in vitro. Endocrinology
141:2054-2061,2000. |
