跳到主要內容

臺灣博碩士論文加值系統

(52.203.18.65) 您好!臺灣時間:2022/01/19 16:21
字體大小: 字級放大   字級縮小   預設字形  
回查詢結果 :::

詳目顯示

: 
twitterline
研究生:羅嘉瑜
研究生(外文):Chia-Yu Lo
論文名稱:子宮頸上皮癌細胞中組織蛋白去乙醯化酶抑制劑降低上皮生長因數誘導產生c-Jun蛋白質量之探討
論文名稱(外文):Histone Deacetylase Inhibitors Attenuate c-Jun Expression Induced by Epidermal Growth Factor in A431 Cells
指導教授:張文昌張文昌引用關係
指導教授(外文):Wen-Chang Chang
學位類別:碩士
校院名稱:國立成功大學
系所名稱:藥理學研究所
學門:醫藥衛生學門
學類:藥學學類
論文種類:學術論文
論文出版年:2002
畢業學年度:90
語文別:中文
論文頁數:87
中文關鍵詞:子宮頸上皮癌細胞組織蛋白去乙醯化酶抑制劑
外文關鍵詞:c-JunA431histone deacetylase inhibitor
相關次數:
  • 被引用被引用:0
  • 點閱點閱:155
  • 評分評分:
  • 下載下載:39
  • 收藏至我的研究室書目清單書目收藏:0
真核細胞的轉錄作用是高度被調控的過程。在組織蛋白的N端會受到乙醯化作用修飾,使染色質結構鬆散,進而產生基因的轉錄作用。先前我們實驗室已經發現在子宮頸上皮癌細胞中,經由上皮生長因子的處理下,會使c-Jun的表現增加,而此增加的情形對其誘導十二位酯氧酵素基因表現是必須且重要的。在本實驗中,主要是想看組織蛋白去乙醯化酶之抑制劑,trichostatin A (TSA) 及sodium butyrate (NaBT),對上皮生長因子誘導之十二位酯氧酵素基因活化有何影響。首先我們確認在TSA處理一小時的細胞中,組織蛋白乙醯化的程度有增加的情形。進而發現在TSA及NaBT的處理下,隨著劑量的增加,會對上皮生長因子誘導的十二位酯氧酵素的活性有抑制的作用。在A431細胞中,EGF的處理下主要活化Ras-ERK及Ras-JNK此兩條訊息傳遞路徑,進而誘導十二脂氧酵素基因表現。實驗結果得知,TSA及NaBT並不會影響EGF對ERK及JNK的磷酸化。我們由體外激酶活性分析法得知,抑制劑TSA及NaBT會減少了上皮生長因子活化JNK的活性,但並不會影響ERK活性。又因為JNK的受質為c-Jun,所以我們進一步釐清TSA及NaBT是否會影響c-Jun的表現。實驗後發現TSA及NaBT會抑制由上皮生長因子所誘導之c-Jun N端磷酸化。也由北方及西方點墨法發現,抑制劑也由於減少了c-Jun mRNA的表現,進而減少其蛋白質量。為了進一步釐清TSA及NaBT影響EGF所促進之c-Jun磷酸化情形,我們送入了一段表現c-Jun N端 (1-220) 的質體進入細胞,發現在表現同樣量的c-Jun N端蛋白質下,處理抑制劑對生長因子所誘導c-Jun Ser63及Ser73的磷酸化也呈現劑量相關性的抑制。因此我們知道在A431細胞中,組織蛋白去乙醯化酶之抑制劑 (TSA、NaBT) 處理了細胞後,除了增加細胞中的乙醯化程度,也非專一性的抑制了上皮生長因子所誘導之JNK活性,進而減少c-Jun磷酸化及蛋白質表現,這一結果導致十二位酯氧酵素活性的抑制。
Eukayotic transcription is a highly regulated process, and histone acetylation is now known to play a major role in this regulation. Acetylation of histone N-termini reduces chromatin condensation; thus gene transcription may activate. Previously, we found that c-Jun induction was required in epidermal growth factor (EGF) induced human 12(S)-lipoxygenase (12(S)-LOX) gene expression in human epidermoid carcinoma A431 cells. In this study, we studied the effect of histone deacetylase inhibitors, trichostatin A (TSA) and sodium butyrate (NaBT) on EGF induced expression of 12(S)-LOX. TSA could enhance the acetylation level of histone H4 within one hour. In order to study the effect of TSA and NaBT on EGF-induced expression of 12(S)-LOX, the 12(S)-LOX enzyme activity was determined. TSA and NaBT inhibited EGF-induced 12(S)-LOX enzyme activity in a dose-dependent manner. Both inhibitors did not have any significant effects on phosphorylation of ERK and JNK, induced by EGF. In the in vitro kinase assay, TSA and NaBT decreased JNK activity in cells, but not ERK activity. Both TSA and NaBT reduced EGF-induced N-terminal phosphorylation and expression of c-Jun. Furthermore, in cells overexpression of c-Jun mutant (N 1-220), which contains c-Jun N-terminal 1-220 amino acids, we found that TSA inhibited EGF-induced c-Jun Ser63 and Ser73 phosphorylation of c-Jun mutant (N 1-220). These results suggest that the inhibition of TSA and NaBT on EGF-induced the expression of 12(S)-LOX was due to inhibit JNK activity and then attenuate N-terminal phosphorylation of c-Jun, which led to the inhibition of c-Jun expression.
目錄
中文摘要----1
英文摘要--- 2
縮寫檢索表---4
第一章 緒 論 5
第二章實驗材料 9
第三章實驗方法 16
第四章實驗結果
第一節 探討TSA在A431細胞中對組織蛋白乙醯化的影響 41
第二節 組織蛋白去乙醯化酶抑制劑TSA及NaBT對EGF誘導的十二位脂氧酵素活性的影響 42
第三節 釐清TSA及NaBT對EGF誘導之MAPK路徑活化的影響
A. TSA及NaBT對EGF誘導之ERK及JNK磷酸化的影響 43
B. 探討TSA及NaBT對EGF誘導之ERK及JNK的激酶活性影響 43
第四節 TSA及NaBT對EGF誘導之c-Jun磷酸化及蛋白質 生合成的影響
A. 抑制劑抑制JNK活性後,對c-Jun磷酸化及蛋白質量的影響 45
B. 利用只具有N端的c-Jun進一步證實TSA及NaBT對c-Jun磷酸化的影響 47
第五章總結與討論 49
參考文獻 54
附圖 64
參考文獻Adler, V., Franklin,C. C., and kraft,A. S. (1992) Phorbol esters stimulate the phosphorylation of c-Jun but not v-Jun: regulation by the N-terminal delta domain. Proc. Natl. Acad. Sci. USA 89, 5341-5345Adler, V., Polotskaya, A., Wagner, F., and Kraft, A. S. (1992) Affinity-purified c-Jun amino-terminal protein kinase requires serine/threonine phosphorylation for activity. J. Biol. Chem. 267, 17001-17005Alani, R., Brown, P., Binetruy, B., Dosaka, H., Rosenberg, R. K., Angel, P., Karin, M., and Birrer, M. J. (1991) The transactivating domain of the c-Jun proto-oncoprotein is required for cotransformation of rat embryo cells. Mol. Cell. Biol. 11, 6286-6295Alberts, B., Bray, D., Lewis, J., Raff, M., Roberts, K., and Watson, J. D. (1994) Molecular biology of the cell. 434Alland, L., Muhle, R., Hou, H., Potes, J., Chin, L., Schreiber-Agus, N., and Depinho, R. A. (1997) Role for N-CoR and histone deacetylase in sin3-mediated transcriptional repression. Nature 387, 49-55Arts, J., Lansink, M., Grimbergen, J., Toet, K. H., and Kooistra, T. (1995) Stimulation of tissue-type plasminogen activator gene expression by sodium butyrate and trichostatin A in human endothelial cells involves histone acetylation. Biochem. J. 310, 171-176Berger, S. L. (2002) Histone modifications in transcriptional regulation. Curr. Opin. Genet. Dev. 12, 142-148Brehm, A., Miska, E. A., McCance, D. J., Reid, J. L., Bannister, A. J., and Kouzarides, T. (1998) Retinoblastoma protein recruits histone deacetylase to repress transcription. Nature 391, 597-601Chen, B. K., Liu, Y. W., Yamamoto, S., and Chang, W. C. (1997) Overexpression of Ha-ras enhances the transcription of human arachidonate 12-lipoxygenase promoter in A431 cells. Biochim. Biophys. Acta. 1344, 270-277Chen, B. K., Kung, H. C., Tsai, T. Y., and Chang, W. C. (2000) Essential role of mitogen-activated protein kinase pathway and c-Jun induction in epidermal growth factor-induced gene expression of human 12-lipoxygenase. Mol. Pharm. 57, 153-161Chen, B. K., and Chang, W. C. (2000) Functional interaction between c-Jun and promoter factor Sp1 in epidermal growth factor-induced gene expression of human 12(S)-lipoxygenase. Proc. Natl. Acad. Sci. 97, 10406-10411Chen, H., Lin, R. J., Xi, W., Wilpitz, D., and Evans, R. M. (1999) Regulation of hormone-induced histone hyperacetylation and gene activation via acetylation of an acetylase. Cell 98, 675-686Chen, L. C. (1998) Regulation of 12-Lipoxygenase expression by transforming growth factor-alpha (TGF-a) in epidermal cells. 國立成功大學藥理學研究所碩士論文Cheung, W. L., Briggs, S. D., and Allis, C. D. (2000) Acetylation and chromosomal functions. Curr. Opin. Cell Biol. 12, 326-333 Coffey, E. T., Smiciene, G., Hongisto, V., Cao, J., Brecht, S., Herdegen, T., and Courtney, M. J. (2002) c-Jun N-terminal protein kinase (JNK) 2/3 is specifically activated by stress, mediating c-Jun activation, in the presence of constitutive JNK1 activity in cerebellar neurons. J. Neurosci. 22, 4335-4345Cohen, L. A., Amin, S., Mark, P. A., Rifkind, R. A., Desai, D., and Richon, V. M. (1999) Chemoprevention of carcinogen-induced mammary tumorigenesis by the hybrid polar cytodifferentiation agent, suberanilohydroxamic acid (SAHA). Anticancer Res. 19, 4999-5006Cousens, L. S., Gallwitz, D., and Alberts, B. M. (1979) different accessibilities in chromatin to histone acetylase. J. Biol. Chem. 254, 1716-1723Cress, W. D., and Seto, E. (2000) Histone deacetylases, transcriptional control, and cancer. J. Cell Physiol. 184, 1-16Cross, M. J., Stewart, A., Hodgkin, M. N., Kerr, D. J., and Wakelam, M. J. O. (1995) Wortmannin and its structural analogue demethoxyviridin inhibit stimulated phospholipase A2 activity in swiss 3T3 cells. J. Biol. Chem. 270, 25352-25355Dérijard, B., Hibi, M., Wu, I. H., Barrett, T., Su, B., Deng, T., Karin, M., and Davis, R. J. (1994) JNK1: A protein kinase stimulated by UV light and Ha-Ras that binds and phosphorylates the c-Jun activation domain. Cell 76, 1025-1037Ferby, I. M., Waga, I., Hoshino, M., Kume, K., and Shimizu, T. (1996) Wortmannin inhibits mitogen-activated protein kinase activation by platelet-activating factor through a mechanism independent of p85/p110-type phosphatidylinositol 3-kinase J. Biol. Chem. 271, 11684-11688Finnin, M. S., Donigian, J. R., Cohen, A., Richon, V. M., Rifkind. R. A., Marks, P. A., Breslow, R., and Pavietich, N. P. (1999) Structures of a histone deacetylase homologue bound to the TSA and SAHA inhibitors. Nature 401, 188-193Forsberg, E. C., and Bresnick, E. H. (2001) Histone acetylation beyond promoters: long-range acetylation patterns in the chromation world. Bioessays 23, 820-830Franklin, C. C., Sanchez, V., Wagner, F., Woodgett, J. R., and Kraft, A. S. (1992) Phorbol ester-induced amino-terminal phosphorylation of human Jun but not JunB regulates transcriptional activity. Pro. Natl Acad. Sci. USA 89, 7247-7251Futamura, M., Monden, T., Fujta, J., Yokoyama, S. and Nishimura, S. (1995) Trichostatin A inhibits both ras-induced neurite outgrowth of PC12 cells and morphological transformation of NIH3T3 cells. Oncogene. 10, 1119-1123 Gille, H., Kortenjann, M., Thomae, O., Moomaw, C., Slaughte,r C., Cobb, M. H., and Shaw, P. E. (1995) ERK phosphorylation potentiates ElK-1-mediated ternary complex formation and transactivation. EMBO J. 14, 951-962Girardot, V., Rabilloud, T., Yoshida, M., Beppu, T., Lawrence, J., and Khochbin, S. (1994) Relationship between core histone acetylation and histone H10 gene activity. Eur. J. Biochem. 224, 885-892 Gregory, P. D., Wagner, K., and Hröz, W. (2001) Histone acetylation and chromatin remodeling. Exp. Cell Res. 265, 195-202Grunstein M. (1997) Histone acetylation in chromatin structure and transcription. Nature 389, 349-352Gupta, S., Barrett, T., Whitmarsh, A. J., Cavanagh, J., Sluss, H. K., Dérijard, B., and Davis, R. J. (1996) Selective interaction of JNK protein kinase isoforms with transcription factors. EMBO J. 15, 2760-2770Han, J. W., Ahn, S. H., Kim, Y. K., Bae, G. U., Yoon, J. W., and Lee H. W. (2001) Activation of p21 WAF1/Cip1 transcription through Sp1 sites by histone deacetylase inhibitor apicidin. J. Biol. Chem 276, 42084-42090Hassig, C. A., Fleischer, T. C., Billin, A. N., Schreiber, S. L., and Ayer, D. E. (1997) Histone deacetylase activity is required for full transcriptional repression by mSin3. Cell 89, 341-347Hebbes, T. R., Thorne, A. W., and Crane-Robinson, C. (1988) A direct link between core histone acetylation and transcriptionally active chromatin. EMBO J. 7, 1395-1402Hibi, M., Lin, A., Smeal, T., Minden, A., and Karin, M. (1993) Identification of an oncoprotein and UV-responsive protein kinase that bind and potentiate the c-Jun activation domain. Gene Dev. 7, 2135-2148Hirschler-Laszkiewicz, I., Cavanaugh, A., Hu, Q., Catania, J., Avantaggiati, M. L., and Rothblum, L. I. (2001) The role of acetylation in rDNA transcription. Nucleic Acids Res. 29, 4114-4124Hoshikawa, Y., Kwon, H. J., Yoshida, M. Horronouchi S., and Beppu, T. (1994) Trichostatin A induces morphological changes and gelsolin expression by inhibiting histone deacetylase in human carcinoma cell lines. Exp. Cell Res. 214, 189-197Huang, Y., Hutter, D., Liu, Y., Wang, X., Sheikh, M. S., Chan, A. M. L., and Holbrook, N. J. (2000) Transforming growth factor-β1 suppresses serum deprivation-induced death of A549 cell through differential effects on c-Jun and JNK activities. J. Biol. Chem. 275, 18234-18242Hurd, C., and Rozengurt, E. (2001) Protein kinase D is sufficient to suppress EGF-induced c-Jun ser63 phosphorylation. Biochem. Biophys. Res. Commun. 282, 404-408Janknecht, R., Ernst, W. H., Pingoud, V., and Nordheim, A. (1993) Activation of ternary complex factor ElK-1 by MAP kinases. EMBO J. 12, 5097-5104Kamitani, H., Taniura, S., Ikawa, H., Watanabe, T., Kelavka,r U. P., and Eling, T. E. (2001) Expression of 15-lipoxygenease-1 is regulated by histone acetylation in human colorectal carcinoma. Carcinogenesis 22, 187-191Kim, M. S., Kwon, H. J., Lee, Y. M., Baek, J. H., Jang, J. E., Lee, S. W., Moon, E. J., Kim, H. S., Lee, S. K., Chung, H. Y., Kim, C. W., and Kim, K. W. (2001) Histone deacetylases induce angiogenesis by negative regulation of tumor suppressor genes. Nat. Med. 7, 437-443Kouzarides, T. (2000) Acetylation: a regulatory modification to rival phosphorylation. EMBO J. 19, 1176-1179Kornberg, R. D. (1999) Eukaryotic transcriptional control. TCB 9, M46-M48Koyama, Y., Adachi, M., Sekiya, M., Takekawa, M., and Imai, K. (2000) Histone deacetylase inhibitors suppress IL-2-mediaed gene expression prior to induction of apoptosis.Blood. 96, 1490-1495 Kuo, M. H., and Allis, C. D. (1998) Roles of histone acetyltransferase and deacetylases in gene regulation. Bioessays 20, 615-626Laura, M. J., Slimane, S. A., and Annick, H. B. (1999) Histone acetylation in signal transduction by growth regulatory signals. Semin. Cell Dev. Biol. 10, 197-203Lee, D. Y., Hayes, J. J., Pruss, D., and Wolffe, A. P. (1993) APositive role for histone acetylation in transcription factor access to nucleosomal DNA. Cell 72, 73-84Marais, R., Wynne, J., and Treisman, R. (1993) The SRF accessory protein Elk-1 contains a growth factor-regulated transcriptional activation domain. Cell 73, 381-393Marks, P. A., Richon, V. M., Breslow, R., and Rifkind, R. A. (2001) Histone deacetylase inhibitors as new cancer drugs. Curr. Opin. Oncol. 13, 477-483Martínez-Balbás, M., Bauer, U.-M., Nielsen, S. J., Brehm, A., and Kouzarides, T. (2000) Regulation of E2F1 activity by acetylation. EMBO J. 19, 662-671Medina, V., Afonso, J. J., Alvarez-Arguelles, H., Hernandez, C., and Gonzalez, F. (1998) Sodium butyrate inhibits carcinoma development in a 1,2-dimethylhydrazine-induced rat colon cancer. JPEN J Parnter Enteral Nutr 22, 14-17Miyashita, T., Tamamoto, H., Nishimune, Y., Monta, T., and Matsushiro A. (1994) Activation of he mouse cytokertin A (endo) gene in tetratocarcinoma F9 cells by the histone deacetylase inhibitor trichostatin A. FEBS Lett. 353, 225-229Mizzen, C. A., and. Allis, C. D (1998) Linking histone acetylation to transcriptional regulation. Cell. Mol. Life Sci. 54, 6-20Murks, R. J. L., and Turner, B. M. (1994) Suppression of heat-shock protein synthesis by short-chain fatty acids and alcohols. Biochim. Biophys. Acta 1223, 23-28Nair, A. R., Boersma, L. J., Schiltz, L., Chaudry, A., and Muschel, R. J. (2001) Paradoxical effects of trichostatin A: inhibition of NF-Y-associated histone acetyltransferase activity, phosphorylation of hGCN5 and downregulation of cyclin A and B1 mRNA. Cancer Lett. 166, 55-64Nakano, K., Mizuno, T., Sowa, Y., Orita, T., Yoshino, T., Okuyama, Y., Fujita, T., Ohtani-Fujita, N., Matsukawa, Y., Tokino, T., Yamagishi, H., Oka, T., Nomura, H., and Sakai, T. (1997) Butyrate activates the p21 WAF1/Cip1 gene promoter through Sp1 sites in a p53-negative human colon cancer cell line. J. Biol. Chem. 272, 22199-22206Nancy, D., Ruiter, D.E, Rob, M. F., Wolthuis, H. V. D., Boudewijn, M. T., and Bos, J. L. (2000) Ras-dependent regulation of c-Jun phosphorylation is mediated by the Ral guanine nucleotide exchange factor-Ral pathway. Mol. Cell Biol. 20, 8480-8488Potapova, O., Basu, S., Mercola, D., and Holbrook ,N. J. (2001) Protective role for c-Jun in the cellular response to DNA damage. J. Biol. Chem. 276, 28546-28553Pulverer, B. J., Kyriakis, J. M., Avruch, J., Nikolakaki, E., and Woodgett, J. R. (1991) Phosphorylation of c-Jun mediated by MAP kinases. Nature 353, 670-674Rice, J. C., and Allis, C. D. (2001) Histone methylation versus histone acetylation: new insights into epigenetic regulation. Curr. Opin. Cell. Biol.13, 263-273Richon, V. M., Emiliani, S., Verdin, E., Webb, Y., Breslow, R., Rifkind, R. A., and Marks, P. (1998) A class of hybrid polar inducers of transformed cell differentiation inhibits histone deacetylases. Proc. Natl. Acad. Sci. USA 95, 3003-3007Sealy, L., and Chalkley R. (1978) DNA associated with hyper-acetylated histone is preferentially digested by DNase I. Nucleic Acids Res. 5, 1863-1876Sever, R., and Turner, R. (1996) The c-Mos proto-oncogene product stimulates c-Jun transcriptional activity by a MAP kinase-dependent mechanism. Biochem. Biophys. Res. Commun. 228, 259-266Shankaranarayanan, P., Chaitidis, P., Khün, H., and Nigam, S. (2001) Acetylation by Histone acetyltransferase CREB-binding protein/p300 of STAT6 is required for transcriptional activation of the 15-Lipoxygenase-1 Gene. J. Biol. Chem. 276, 42753-42760 Spencer, V. A., and Davie, J. R. (1999) Role of covalent modifications of histones in regulating gene expression. Gene 240, 1-12Sterner, D. E., and Berger, S. L. (2000) Acetylation of histones and transcription-related factors. Microbiol. Mol. Biol. Rev. 64, 435-459Struhl, K. (1998) Histone acetylation and transcriptional regulatory mechanisms. Genes Dev. 12, 599-606Swank, M. W., and Sweatt, J. D. (2001) Increased histone acetyltransferase and lysine acetyltransferase activity and biphasic activation of the ERK/RSK cascade in insular cortex during novel taste learning. J. Neurosci. 21, 3383-3391Talukder, A. H., Jørgensen, H. F., Mandal, M., Mishra, S. K., Vadlamudi, R. K., Clark, B. F. C., Mendelsohn, J., and Kumar, R. (2001) Regulation of Elongation factor-1α expression by growth factors and anti-receptor blocking antibodies. J. Biol. Chem. 276, 5636-5642Thomson, S., Mahadevan, L. C., and Clayton, A. L. (1999) MAP kinase-mediated signaling to nucleosomes and immediate-early gene induction. Semin. Cell Dev. Biol. 10, 205-214Thomson, S., Clayton, A. L., and Mahadevan, L. C. (2001) Independent dynamic regulation of histone phosphorylation and acetylation during immediate-early gene induction. Mol. Cell 8, 1231-1241Velazquez, O.C., Jabbar, A., DeMatteo, R.P., and Rombeau, J.L. (1996) Butyrate inhibits seeding and growth of colorectal metastases to the liver in mice. Surgery 120, 440-447Vidali, G., Boffa L. C., Bradbury, E. M., and Allfery, V. G. (1978) Butyrate suppression of histone deacetylation leads to accumulation of multiacetylated forms of histone H3and H4 and increased DNase I sensitivity of theassociated DNA sequences. Proc. Natl. Acad. Sci. 75, 2239-2243 Watson, A., Eilers, A., Lallemand, D., Kyriakis, J., Rubin, L., and Ham, W. (1998) Phosphorylation of c-Jun is necessary for apoptosis induced by survival signal withdrawal in cerebellar granule neurons. J. Neurosci. 18, 751-762Weitzman, J. B. (2000) JNK Curr. Biol. 10, 1-2Witt, O., Sand, K., and Pekrun, A. (2000) Butyrate-induced erythroid differentiation of human K562 leukemia cells involves inhibition of ERK and activation of p38 MAP kinase pathways. Blood 95, 2391-2395Weidle, U. H., and Grossmann, A. (2000) Inhibition of histone deacetylases: a new strategy to target epigenetic modifications for anticancer treatment. Anticancer Res. 20, 1471-1486Wisdom, R., Johnson, R. S., and Moore, C. (1999) c-Jun regulates cell cycle progression and apoptosis by distinct mechanisms. EMBO J. 18, 188-197Wu, J. T., Archer, S. Y., Hinnebusch, B., Meng, S., and Richard, A. H. (2001) Transient vs. prolonged histone hyperacetylation: effects on colon cancer cell growth, differentiation, and apoptosis. Am. J. Physiol. Gastrointest Liver Physiol. 280, G482-G490Yoshida, M., and Horinouchi, S. (1999) Trichostation and leptomycin: inhibition of histone deacetylation and signal-dependent nuclear export. Ann. N.Y. Acad. Sci. 886, 23-25Yoshida, M., Horinouchi, S., and Beppu, T. (1995) Trichostatin A and trapoxin: novel chemical probes for the role of histone acetylation in chromatin structure and function. Bioessays. 17, 423-430
QRCODE
 
 
 
 
 
                                                                                                                                                                                                                                                                                                                                                                                                               
第一頁 上一頁 下一頁 最後一頁 top