| Project/Area Number |
17580118
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Food science
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| Research Institution | Tokyo University of Agriculture |
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Principal Investigator |
YAMAMOTO Yuji Tokyo University of Agriculture, Department of Applied Biology and Chemistry, Associate Professor, 応用生物科学部, 助教授 (50240130)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2006: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 2005: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Keywords | Tumor Suppressor gene / Palmitoylation / Signal transduction / Intracellular localization / 脂質 / シグナル伝達 / 癌抑制機構 / シグナル伝達機構 / 脂肪酸付加 |
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| Research Abstract |
Tuberous sclerosis complex (TSC) is an autosomal dominantly inherited tumor syndrome. TSC occurs through loss of hetero-zygosity of either TSC1 or TSC2 gene which encode hamartin or tuberin. Hamartin-Tuberin complex functions as a GTPase-activating protein against Rheb (Ras homolog enriched in brain), which, in turn, regulates m-TOR (mammalian target of rapamycin) signaling. Even Hamartin has been classified as an integral membrane protein, we have previously reported that both Hamartin and Tuberina can be detected In microsomal and cytosolic fraction.
Thus, we hypothized that Tuberin may be attached to the membrane through To prove this, we first showed that tuberin existed in the membrane fraction in TSC14-ce11 which clearly shows that tuberin does not require hamartin for its membrane binding. Next, Cos-1 cells were treated with tunicamycin, a plamitoylation inhibitor and its membrane localization was investigated. Tuberin located In the microsome fraction was no longer observed after the drug treatment and we also confirmed Tuberin dissociation from the membrane by transiently transfecting Cos-1 cells expressing GFP-TSC2 by under confocal microscopy. Moreover, using immunoprecipitation technique we found that tuberin was non longer forming a hetero-complex with hamartin after tunicamycin treatment. We also found that When Tuberin is dissociated from the membrane it looses its function as a Rheb GAP and forms a hetero-complex with 14-3-3 protein. We also analyzed the cytosolic fraction and identified a fraction where tuberin existed without Hamartin.
These data indicate that not Hamartin but tuberin palmitoylation is necessary for its membrane localization and may alter its function through regulating the complex formation with hamartin.
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