Development of the mammalian brain proceeds via a series of carefully regulated steps; interference with any of these steps has profound consequences on normal development. Critical to normal morphogenesis is precise temporal expression of cell adhesion molecules (CAMs) and of cytoskeletal modifications which are hallmarks of these steps. Data obtained during the previous funding period indicate that while microtubules are susceptible to methylmercury (MeHg), CAMs are also critically vulnerable to MeHg at specific developmental stages. There is also clear evidence that targeting of CAMs by MeHg leads to an interruption of the essential functional linkage between cell adhesion molecules and the cytoskeleton. Since the nature of impaired brain morphogenesis reflects the developmental step disrupted, and CAMs are differentially expressed at the various stages, it is hypothesized that disturbance of brain development by MeHg is caused by perturbation of CAMs at critical stages or """"""""windows"""""""" of neural morphogenesis. The relationships between MeHg, CAMs, and CAM-cytoskeletal linkages will be investigated by addressing the following specific aims: 1) To determine if MeHg acts directly on CAMs, or via CAM biosynthesis, to differentIally alter the expression and function of CAMs at particular developmental stages. 2) To ascertain the mechanism by which MeHg disturbs the linkage between CAMs and cytoskeleton. 3) To develop a model which permits experimental control of CAM expression (using cDNA transfection techniques) to examine critical susceptibilities of CAMs to MeHg and subsequent influences on cytoskeleton. This project represents the first systematic study of the effects of a toxic metal on CAMs during brain development.
The specific aims will be addressed using a combination of contemporary molecular and cellular techniques applied to models at the cell (cell culture), tissue (hippocampal or cerebellar slice), and whole animal levels of organization. Members of the calcium-dependent (N-cadherin) and calcium- independent (NCAM, L1) families of CAMs will be examined to determine the effects of MeHg on their expression and modulation, and the integrity of their linkage to cytoskeleton. Immunofluorescence and immunohistochemical microscopy, in situ hybridization, immunoblot analysis, quantitative ELISA, and functional binding assays will be used to provide overlapping approaches to unravelling MeHg-CAM interactions. Finally, the relationship between CAMs and cytoskeleton under normal and toxicant- conditions will be determined in cultured neurons and in 3T3 fibroblasts transfected to express specific CAMs prior to and following chemical perturbation of specific cytoskeletal elements.

Agency
National Institute of Health (NIH)
Institute
National Institute of Environmental Health Sciences (NIEHS)
Type
Research Project (R01)
Project #
5R01ES004976-08
Application #
2018343
Study Section
Toxicology Subcommittee 2 (TOX)
Project Start
1989-01-01
Project End
1999-12-31
Budget Start
1997-01-01
Budget End
1999-12-31
Support Year
8
Fiscal Year
1997
Total Cost
Indirect Cost
Name
Rutgers University
Department
Pharmacology
Type
Schools of Pharmacy
DUNS #
038633251
City
New Brunswick
State
NJ
Country
United States
Zip Code
08901
Polunas, Marianne; Halladay, Alycia; Tjalkens, Ronald B et al. (2011) Role of oxidative stress and the mitochondrial permeability transition in methylmercury cytotoxicity. Neurotoxicology 32:526-34
Pyle, S J; Roberts, K G; Reuhl, K R (2001) Delayed expression of the NFH subunit in differentiating P19 cells. Brain Res Dev Brain Res 132:103-6
Angner, R T; Kelly, R M; Wiley, R G et al. (2000) Preferential destruction of cerebellar Purkinje cells by OX7-saporin. Neurotoxicology 21:395-403
Dey, P M; Burger, J; Gochfeld, M et al. (2000) Developmental lead exposure disturbs expression of synaptic neural cell adhesion molecules in herring gull brains. Toxicology 146:137-47
Dey, P M; Gochfeld, M; Reuhl, K R (1999) Developmental methylmercury administration alters cerebellar PSA-NCAM expression and Golgi sialyltransferase activity. Brain Res 845:139-51
Dey, P M; Polunas, M A; Philbert, M A et al. (1997) Altered expression of polysialylated NCAM in mouse hippocampus following trimethyltin administration. Neurotoxicology 18:633-43
Graff, R D; Falconer, M M; Brown, D L et al. (1997) Altered sensitivity of posttranslationally modified microtubules to methylmercury in differentiating embryonal carcinoma-derived neurons. Toxicol Appl Pharmacol 144:215-24
Stern, S; Reuhl, K; Soderholm, S et al. (1996) Perinatal methanol exposure in the rat. I. Blood methanol concentration and neural cell adhesion molecules. Fundam Appl Toxicol 34:36-46
Beiswanger, C M; Diegmann, M H; Novak, R F et al. (1995) Developmental changes in the cellular distribution of glutathione and glutathione S-transferases in the murine nervous system. Neurotoxicology 16:425-40
Dey, P M; Graff, R D; Lagunowich, L A et al. (1994) Selective loss of the 180-kDa form of the neural cell adhesion molecule in hippocampus and cerebellum of the adult mouse following trimethyltin administration. Toxicol Appl Pharmacol 126:69-74

Showing the most recent 10 out of 19 publications