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Identifying and modeling the contrib...

Watt, James Douglas.

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Identifying and modeling the contribution of nuclear receptors to environmental obesogen-induced toxicity in bone.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	Identifying and modeling the contribution of nuclear receptors to environmental obesogen-induced toxicity in bone./
作者:	Watt, James Douglas.
出版者:	Ann Arbor : ProQuest Dissertations & Theses, : 2016,
面頁冊數:	205 p.
附註:	Source: Dissertation Abstracts International, Volume: 78-05(E), Section: B.
Contained By:	Dissertation Abstracts International78-05B(E).
標題:	Environmental health. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10190771
ISBN:	9781369358001

Identifying and modeling the contribution of nuclear receptors to environmental obesogen-induced toxicity in bone.
Watt, James Douglas.

Identifying and modeling the contribution of nuclear receptors to environmental obesogen-induced toxicity in bone. - Ann Arbor : ProQuest Dissertations & Theses, 2016 - 205 p.

Source: Dissertation Abstracts International, Volume: 78-05(E), Section: B.

Thesis (Ph.D.)--Boston University, 2016.

Bone is a dynamic tissue, where bone forming osteoblasts and bone resorbing osteoclasts maintain homeostasis. Research into bone toxicology has largely focused on pharmaceutical side effects adversely affecting bone development. However, many environmental toxicants can regulate bone homeostasis. Recently, the nuclear receptor peroxisome proliferator activated receptor gamma (PPARgamma) has emerged as an important target of environmental toxicants. PPARgamma dimerizes with the retinoid-X receptor alpha (RXRalpha), is a central transcription factor in adipogenesis, and in bone can transdifferentiate osteoblasts into adipocytes by suppressing osteogenic pathways. The central hypothesis of this dissertation is that environmental chemicals can adversely affect bone homeostasis by activating nuclear receptors in bone cells -- particularly osteoblasts and osteoclasts -- to perturb cellular differentiation and function. Three study aims were developed to test and refine this hypothesis. First, a set of structurally diverse environmental PPARgamma agonists were individually applied to mouse primary bone marrow mesenchymal stromal cell cultures undergoing osteogenic differentiation. In vitro PPARgamma ligand treatment suppressed osteogenesis and stimulated adipogenesis. Organotin compounds (tributyltin, triphenyltin) in particular more efficaciously suppressed osteogenesis. The second aim characterized the effects of in vivo tributyltin exposure on bone microarchitecture in female C57Bl/6 mice. Tributyltin exposure resulted in a thinner cortical bone, but significantly increased trabecular mineralization. Further analyses suggested that tributyltin did not suppress osteoclast numbers but rather changed osteoclast function, minimally attenuating the resorptive function and enhancing their ability to generate osteogenesis-stimulating factors. Furthermore, tributyltin activated not only PPARgamma, but also RXR and liver X receptors. The third aim established the utility of Generalized Concentration Addition in modeling PPARgamma activation by mixtures of full and partial PPARgamma agonists. A complex mixture of multiple phthalate compounds activated an in vitro PPARgamma reporter assay, and the individual dose-responses of each compound were used to construct modeled responses. The comparisons of empirical data and model predictions supported the use of Generalized Concentration Addition in modeling a complex mixture of environmental PPARgamma agonists. Together, these studies support and establish important toxicological mechanisms related to PPARgamma and RXRalpha activation in different aspects of bone biology and provide a basis for studying mixture effects of PPARgamma agonists.

ISBN: 9781369358001Subjects--Topical Terms:

543032
Environmental health.

Identifying and modeling the contribution of nuclear receptors to environmental obesogen-induced toxicity in bone.
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