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Identification of functional dopamine receptors in human teratocarcinoma NT2 cells
Caroline Sodja1, Hung Fang, Tina Dasgupta
1Apoptosis Research Group, Institute for Biological Sciences, National Research Council of Canada, 1500 Montreal Road, Bldg. M-54, Ottawa, ON, K1A 0R6, Canada.
Abstract:
In search of a cellular model suitable for studying molecular events contributing to brain disorders, we have characterised the expression and functionality of dopamine receptors in human teratocarcinoma NT2 cells. The cells were differentiated by a 4-week retinoic acid treatment, followed by a 3-week mitotic inhibitor treatment in the absence of retinoic acid. The messages of two D(2)-like family members, D(2L) and D(3), were expressed in undifferentiated NT2 cells. The retinoic acid treatment resulted in increased expression of both spliced variants of the D(2) receptor, D(2L) and D(2S) isoforms and a significant induction of D(1) and D(5) gene transcripts. The same treatment turned off expression of the D(3) gene. Further induction of the D(5) gene was observed in the post-mitotic NT2N neurons. The NT2N cells stained positively for D(2) and D(5) receptor proteins, and the intracellular cyclic AMP level increased in response to forskolin, dopamine and the D(1)-receptor agonist SKF-81297. Furthermore, dopamine was ineffective in the presence of the D(2) receptor agonist PPHT and the D(1) receptor antagonist cis-(z)-flupenthixol. These results indicated that upon ligand/agonist/antagonist binding, the receptors could be coupled to the adenylyl cyclase system, hence were functional. To our knowledge, NT2 is the only human immortalized cell line expressing functional dopamine receptors of both families.
Insights
This study identifies a human immortalized cell line, NT2 cells, as a valuable model for brain disorder research. Differentiated NT2 cells express functional dopamine receptors (D1, D2, D5), crucial for understanding neurological mechanisms.
Area of Science:
- Neuroscience
- Cell Biology
- Pharmacology
Background:
- Studying molecular mechanisms of brain disorders requires appropriate cellular models.
- Dopamine receptors play critical roles in various neurological functions and disorders.
- Human immortalized cell lines offer a consistent and accessible platform for such research.
Purpose of the Study:
- To characterize the expression and functionality of dopamine receptors in human teratocarcinoma NT2 cells.
- To establish NT2 cells as a suitable cellular model for investigating dopamine receptor-related molecular events in brain disorders.
Main Methods:
- NT2 cells were differentiated using retinoic acid and mitotic inhibitors.
- Gene expression of dopamine receptor subtypes (D1, D2, D3, D5) was analyzed.
- Receptor protein expression was confirmed using staining.
- Functional assays measured intracellular cyclic AMP levels in response to receptor stimulation.
Main Results:
- Undifferentiated NT2 cells expressed D2-like receptors (D2L, D3).
- Differentiation induced D1, D5, and D2 receptor (D2L, D2S) expression while downregulating D3.
- Differentiated NT2N neurons showed further D5 induction.
- NT2N cells expressed D2 and D5 receptor proteins and exhibited functional coupling to the adenylyl cyclase system.
Conclusions:
- NT2 cells, after differentiation, express functional dopamine receptors D1, D2, and D5.
- This cell line represents a unique human immortalized model for studying dopamine receptor family function.
- These findings support the utility of NT2 cells for brain disorder research.