Abstract

This project is focused on the role of local factors in the accelerated bone turnover following estrogen withdrawal leading to bone loss and osteoporosis. IL-1 and TNF have been implicated in this process by studies showing that bone loss in ovariectomized mice can be blocked by IL-1 and TNF inhibitors. It is hypothesized that increased IL-1 TNF activity after estrogen withdrawal may inhibit osteoblastogenesis and reduce the formation response to resorption. Using a murine model of estrogen withdrawal, we will examine production of both spontaneous and induced IL-1 and TNF in bone and bone marrow, as well as IL-1 and TNF bioactivity in marrow supermatants. Mice will be sham-operated, with placement of placebo pellets, and ovariectomized, with placement of placebo or estradiol pellets, and sacrificed at varying times thereafter, mRNAs for IL-1alpha and beta, IL-1ra -, IL-1 receptor types l and ll, TNF, and TNF receptor types l and ll will be analyzed. Cytokine levels will be determined by ELISA in bone marrow supernatants. Mice transgenic for IL-1 or TNF promoter-CAT reporter constructs will also be studied. To assess effects of estrogen withdrawal on osteoprogenitors, marrow stromal cells (MSC) from these mice will be cultured for 12 and 21 d and analyzed for alkaline phosphatase positive colonies and mineralizing nodules. To asses the roles of IL-1 and TNF, we will examine their in vitro effects on cultured MSC and the effects of IL-1 and TNF inhibitors on exvivo MSC cultures from estrogen withdrawn mice. MSC from mice deficient for IL-1 and TNF receptors will also be studies. Effects on MSC differentiation of marrow supernantants from SHAM, OVX and OVX plus E mice will be examined plus/minus IL-1 and TNF inhibitors. Finally, we will develop constructs to target overexpression of IL-1ra and TNFbp to bone using the 3.6 COL1A1 promoter. After in vitro testing, transgenic mice lines will be developed for each inhibitor and bred together to develop lines expressing both inhibitors. Bone loss in overexpressing mice and wild type controls will be compared after estrogen withdrawal by static and dynamic histomorphometry.

  Funding Agency

Agency
National Institute of Health (NIH)
Institute
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Type
Research Program Projects (P01)
Project #
5P01AR038933-12
Application #
6201506
Study Section
Project Start
1999-08-01
Project End
2000-07-31
Budget Start
1997-10-01
Budget End
1998-09-30
Support Year
12
Fiscal Year
1999
Total Cost
Indirect Cost

  Institution

Name
University of Connecticut
Department
Type
DUNS #
City
Farmington
State
CT
Country
United States
Zip Code
06030

  Publications

Marijanovic, Inga; Kronenberg, Mark S; Erceg Ivkosic, Ivana et al. (2009) Comparison of proliferation and differentiation of calvarial osteoblast cultures derived from Msx2 deficient and wild type mice. Coll Antropol 33:919-24
Zhang, W; Pantschenko, A G; McCarthy, M-B et al. (2007) Bone-targeted overexpression of Bcl-2 increases osteoblast adhesion and differentiation and inhibits mineralization in vitro. Calcif Tissue Int 80:111-22
He, Jianing; Rosen, Clifford J; Adams, Douglas J et al. (2006) Postnatal growth and bone mass in mice with IGF-I haploinsufficiency. Bone 38:826-35
Lengner, Christopher J; Steinman, Heather A; Gagnon, James et al. (2006) Osteoblast differentiation and skeletal development are regulated by Mdm2-p53 signaling. J Cell Biol 172:909-21
Delahunty, K M; Shultz, K L; Gronowicz, G A et al. (2006) Congenic mice provide in vivo evidence for a genetic locus that modulates serum insulin-like growth factor-I and bone acquisition. Endocrinology 147:3915-23
Sher, L B; Harrison, J R; Adams, D J et al. (2006) Impaired cortical bone acquisition and osteoblast differentiation in mice with osteoblast-targeted disruption of glucocorticoid signaling. Calcif Tissue Int 79:118-25
Jiang, Jin; Lichtler, Alexander C; Gronowicz, Gloria A et al. (2006) Transgenic mice with osteoblast-targeted insulin-like growth factor-I show increased bone remodeling. Bone 39:494-504
Lee, Sun-Kyeong; Gardner, Amy E; Kalinowski, Judith F et al. (2006) RANKL-stimulated osteoclast-like cell formation in vitro is partially dependent on endogenous interleukin-1 production. Bone 38:678-85
Pantschenko, Alexander G; Zhang, Wenjian; Nahounou, Marcia et al. (2005) Effect of osteoblast-targeted expression of bcl-2 in bone: differential response in male and female mice. J Bone Miner Res 20:1414-29
Kim, Nacksung; Kadono, Yuho; Takami, Masamichi et al. (2005) Osteoclast differentiation independent of the TRANCE-RANK-TRAF6 axis. J Exp Med 202:589-95

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