A gene for the α-subunit of a GTP binding protein (Gα-olf) localized to the 18p11 region has been implicated as a susceptibility gene for bipolar affective disorder (BP). The heterotrimeric G proteins consisting of α, β, and γ subunits function to relay information from cell surface receptors to intracellular effectors. We focus on the α-subunit of G proteins because it binds and hydrolyzes GTP. Lithium inhibits the function of α subunits by decreasing the affinity with which they bind GTP. Our hypothesis is that there is a perturbation in levels of Gα-olf in BPI subjects and lithium treatment modulates the level and interacting ability of the protein. We cultured lymphoblastoid cell lines derived from 10 BPI patients and 10 unaffected subjects. About 10 × 106 cells from each of the 20 cell lines were grown in the presence of lithium for 16 hours. An equal amount (50 μg) of total cellular proteins was analyzed by polyacrylamide gel electrophoresis followed by western immunoblotting using the following antibodies: i) anti Gα-olf is a polyclonal IgG against an epitope corresponding to amino acids 100-118 mapping within a highly divergent domain of Gα-olf of rat origin which is reactive with mammalian protein but not with other subunits, ii) anti Gα-z is a polyclonal IgG against an epitope corresponding to amino acids 93-112 mapping within a highly divergent domain of Gα-z of human origin, and iii) anti-HSP70 is a monoclonal antibody against the heat shock protein. We detected no cellular toxicity with lithium treatment (1 mM) as measured by the trypan blue exclusion method and LDH assay. In western immunoblots, we observed a distinct Gα-olf protein band of 46 kDa. For a control, we detected a sharp HSP band of 72 kDa from each cell extract. We did not observe any statistical difference in levels of Gα-olf between untreated and lithium-treated samples. There is no significant association between bipolar diagnosis and outcome measure (Gα-olf). The results do not support the hypothesis that Gα-olf is generally implicated in bipolar illness or lithium treatment though much larger samples would be needed to test hypotheses regarding subgroups. Our initial results demonstrate that lymphoblastoid cell lines from the subjects can be used to determine the level of a protein product of the gene implicated for BP and that the cell culture system can be further used to study the mechanism of a drug at the cellular and molecular level.
|Original language||English (US)|
|Number of pages||1|
|Journal||American Journal of Medical Genetics - Neuropsychiatric Genetics|
|State||Published - Nov 6 1998|
ASJC Scopus subject areas
- Psychiatry and Mental health
- Cellular and Molecular Neuroscience