細胞極化作用所促進的方向性移動，對於生物體在生理以及病理上扮演著重要角色。先前的研究指出，當細胞移動時，鈣離子會增加並聚集在極化細胞的尾端。在非興奮性細胞中，鈣池調控鈣離子流入(SOCE)為主要鈣離子從細胞外流入細胞內的方式，其中主要參與的分子為:基質交互分子(STIM1)、瞬態電壓感受器通道(TRPC1)和鈣池調控鈣離子通道蛋白(Orai1)。由SITM1、 TRPC1和/或Orai1所組成的SOCE活化態通道複合體常會分布於富含caveolin-1 (Cav1)的脂質筏和質膜微囊中。我們的研究目的在於探討鈣離子或SOCE活性於細胞極化過程中所扮演的角色。本研究乃是利用人類惡性骨肉瘤細胞U2OS為材料，此細胞在自然狀態移動時便具有顯著的極化形態。從本論文結果我們得知，鈣離子集中在細胞尾端以及細胞外鈣離子流入對極化作用是很重要的，其中利用專一性抑制劑降低SOCE的活性會抑制極化作用的形成。此外，Cav1和SOCE的複合體大多都聚集在極化細胞的尾端，其中，我們利用TRPC家族抑制劑、脂質筏形成抑制劑及過量表現Cav1都可以降低細胞極化作用形成，但移除STIM1卻不會抑制細胞的極化作用。另一方面，當細胞培養於較軟的基質環境下，極化細胞比例和SOCE的活性都有顯著下降的趨勢，此現象有可能是由細胞骨架中之肌動蛋白絲和微管的重組失調所造成。綜合上述實驗結果，我們證明了細胞骨架的架構和SOCE的極化分布對於細胞形成極化形態扮演很重要的角色，然而，其中詳盡之分子傳遞機制仍需更進一步探討釐清。

Formation of cell polarity is essential for directional migration which plays an important role in physiological and pathological processes of an organism. Previous studies have indicated that calcium (Ca2+) is concentrated at the rear end of polarized cells. Store-operated Ca2+ entry (SOCE) is the major form of extracellular Ca2+ influx in non-excitable cells, and the major molecular components in regulation of SOCE are the ER Ca2+ sensor stromal interaction molecule1 (STIM1) and two plasma membrane Ca2+ channels transient receptor potential channel 1 (TRPC1) and Orai1. Activated SOCE molecular complexes are present in caveolin-1 (Cav1)-rich lipid rafts/caveolae where the SOCE channelosome, the signaling proteins STIM1 associated with ion channels TRPC1 and/or Orai1, is formed. In order to examine the role of Ca2+ or SOCE in the formation of cell polarity, we employed human bone osteosarcoma U2OS cells which exhibited distinct morphological polarity during directional migration. Our studies showed that Ca2+ was concentrated at the rear end of cells and extracellular Ca2+ influx was important for cell polarization. Inhibition of SOCE by specific inhibitors SKF96365, YM58483, Gd3+ and La3+ disrupted the formation of cell polarity in a dose-dependent manner. Moreover, Cav1 and STIM1/TRPC1/Orai1 channelosomal components were concentrated at the rear end of polarized cells. Non-selective blocker of the TRPC family, flufenamic acid (FFA), also reduced cell polarization. However, knocking down STIM1 had no effect on the formation of cell polarity. Furthermore, disruption of lipid rafts or overexpression of Cav1 contributed to downregulation of cell polarity. On the other hand, we also showed that cell polarity and SOCE activity were markedly decreased by low substrate rigidity that may cause by disorganization of actin filaments and microtubules. Taken together, we conclude that the architecture of cytoskeletons and/or polarized distribution of SOCE play an important roles in the formation of cell polarity, which underlying mechanism remains to be investigated.

Abed, E., D. Labelle, C. Martineau, A. Loghin and R. Moreau. 2009. Expression of transient receptor potential (TRP) channels in human and murine osteoblast-like cells. Molecular Membrane Biology. 26: 146-158.
Ananthakrishnan, R. and A. Ehrlicher. 2007. The forces behind cell movement. International Journal of Biological Sciences. 3: 303-317.
Beardsley, A., K. Fang, H. Mertz, V. Castranova, S. Friend and J. Liu. 2005. Loss of caveolin-1 polarity impedes endothelial cell polarization and directional movement. The Journal of Biological Chemistry. 280: 3541-3547.
Berridge, M.J., M.D. Bootman and H.L. Roderick. 2003. Calcium signalling: dynamics, homeostasis and remodelling. Nature Reviews. Molecular Cell biology. 4: 517-529.
Bootman, M.D., T.J. Collins, C.M. Peppiatt, L.S. Prothero, L. MacKenzie, P. De Smet, M. Travers, S.C. Tovey, J.T. Seo, M.J. Berridge, F. Ciccolini and P. Lipp. 2001. Calcium signalling-an overview. Seminars in Cell & Developmental Biology. 12: 3-10.
Brandt, D.T. and R. Grosse. 2007. Get to grips: steering local actin dynamics with IQGAPs. EMBO Reports. 8: 1019-1023.
Cantiani, L., M.C. Manara, C. Zucchini, P. De Sanctis, M. Zuntini, L. Valvassori, M. Serra, M. Olivero, M.F. Di Renzo, M.P. Colombo, P. Picci and K. Scotlandi. 2007. Caveolin-1 reduces osteosarcoma metastases by inhibiting c-Src activity and met signaling. Cancer Research. 67: 7675-7685.
Chen, Y.T., Y.F. Chen, W.T. Chiu, Y.K. Wang, H.C. Chang and M.R. Shen. 2013a. The ER Ca2+ sensor STIM1 regulates actomyosin contractility of migratory cells. Journal of Cell Science. 126: 1260-1267.
Chen, Y.T., Y.F. Chen, W.T. Chiu, Y.K. Wang, H.C. Chang and M.R. Shen. 2013b. Microtubule-associated histone deacetylase 6 supports the calcium store sensor STIM1 in mediating malignant cell behaviors. Cancer Research.
Cheng, K.T., X. Liu, H.L. Ong, W. Swaim and I.S. Ambudkar. 2011. Local Ca2+ entry via Orai1 regulates plasma membrane recruitment of TRPC1 and controls cytosolic Ca2+ signals required for specific cell functions. PLoS Biology. 9: e1001025.
DeHaven, W.I., B.F. Jones, J.G. Petranka, J.T. Smyth, T. Tomita, G.S. Bird and J.W. Putney, Jr. 2009. TRPC channels function independently of STIM1 and Orai1. The Journal of Physiology. 587: 2275-2298.
Derouiche, S., M. Warnier, P. Mariot, P. Gosset, B. Mauroy, J.L. Bonnal, C. Slomianny, P. Delcourt, N. Prevarskaya and M. Roudbaraki. 2013. Bisphenol A stimulates human prostate cancer cell migration via remodelling of calcium signalling. Springer Plus. 2:54
Dietrich, A., H. Kalwa, U. Storch, M. Mederos, Y Schnitzler, B. Salanova, O. Pinkenburg, G. Dubrovska, K. Essin, M. Gollasch, L. Birnbaumer and T. Gudermann. 2007. Pressure-induced and store-operated cation influx in vascular smooth muscle cells is independent of TRPC1. Pflugers Archiv : European Journal of Physiology. 455: 465-477.
Espinosa-Tanguma, R., C. O’Neil, T. Chrones, J.G. Pickering and S.M. Sims. 2011. Essential role for calcium waves in migration of human vascular smooth muscle cells. American Journal of Physiology. Heart and Ciculatory. 301: H301-H323.
Fabian, A., T. Fortmann, P. Dieterich, C. Riethmuller, P. Schon, S. Mally, B. Nilius and A. Schwab. 2008. TRPC1 channels regulate directionality of migrating cells. Pflugers Archiv : European Journal of Physiology. 457: 475-484.
Galan, C., N. Dionisio, T. Smani, G.M. Salido and J.A. Rosado. 2011. The cytoskeleton plays a modulatory role in the association between STIM1 and the Ca2+ channel subunits Orai1 and TRPC1. Biochemical Pharmacology. 82: 400-410.
Gardel, M.L., I.C. Schneider, Y. Aratyn-Schaus and C.M. Waterman. 2010. Mechanical integration of actin and adhesion dynamics in cell migration. Annual Review of Cell and Developmental Biology. 26: 315-333.
Goetz, J.G., B. Joshi, P. Lajoie, S.S. Strugnell, T. Scudamore, L.D. Kojic and I.R. Nabi. 2008a. Concerted regulation of focal adhesion dynamics by galectin-3 and tyrosine-phosphorylated caveolin-1. The Journal of Cell Biology. 180: 1261-1275.
Goetz, J.G., P. Lajoie, S.M. Wiseman and I.R. Nabi. 2008b. Caveolin-1 in tumor progression: the good, the bad and the ugly. Cancer Metastasis Reviews. 27: 715-735.
Gottlieb, P., J. Folgering, R. Maroto, A. Raso, T.G. Wood, A. Kurosky, C. Bowman, D. Bichet, A. Patel, F. Sachs, B. Martinac, O.P. Hamill and E. Honore. 2008. Revisiting TRPC1 and TRPC6 mechanosensitivity. Pflugers Archiv : European Journal of Physiology. 455: 1097-1103.
Grande-Garcia, A. and M.A. del Pozo. 2008. Caveolin-1 in cell polarization and directional migration. European Journal of Cell Biology. 87: 641-647.
Grande-Garcia, A., A. Echarri, J. de Rooij, N.B. Alderson, C.M. Waterman-Storer, J.M. Valdivielso and M.A. del Pozo. 2007. Caveolin-1 regulates cell polarization and directional migration through Src kinase and Rho GTPases. The Journal of Cell Biology. 177: 683-694.
Huang, G.N., W. Zeng, J.Y. Kim, J.P. Yuan, L. Han, S. Muallem and P.F. Worley. 2006. STIM1 carboxyl-terminus activates native SOC, Icrac and TRPC1 channels. Nature Cell Biology. 8: 1003-1010.
Huttenlocher, A. 1997. Regulation of cell migration by the calcium-dependent protease calpain. The Journal of Biological Chemistry. 272: 32719-32722.
Kaverina, I. and A. Straube. 2011. Regulation of cell migration by dynamic microtubules. Seminars in Cell & Developmental Biology. 22: 968-974.
Khyrul, W.A., D.P. LaLonde, M.C. Brown, H. Levinson and C.E. Turner. 2004. The integrin-linked kinase regulates cell morphology and motility in a rho-associated kinase-dependent manner. The Journal of Biological Chemistry. 279: 54131-54139.
Kobayashi, T. and M. Sokabe. 2010. Sensing substrate rigidity by mechanosensitive ion channels with stress fibers and focal adhesions. Current Opinion in Cell Biology. 22: 669-676.
Lauffenburger, D.A. and A.F. Horwitz. 1996. Cell Migration: A physically integrated molecular process. Cell. 84: 359-369.
Lamb, J.A., P.G. Allen, B.Y. Tuan and P.A. Janmeygl. 1993. Modulation of Gelsolin Function. The Journal of Biological Chemistry. 268: 8999-9004.
Li, J., P. Sukumar, C.J. Milligan, B. Kumar, Z.Y. Ma, C.M. Munsch, L.H. Jiang, K.E. Porter and D.J. Beech. 2008. Interactions, functions, and independence of plasma membrane STIM1 and TRPC1 in vascular smooth muscle cells. Circulation Research. 103: e97-104.
Li, R., and G.G. Gundersen. 2008. Beyond polymer polarity: how the cytoskeleton builds a polarized cell. Nature Reviews. Molecular Cell biology. 9: 860-873.
Machesky, L.M. and A. Hall. 1997. Role of actin polymerization and adhesion to extracellular matrix in Rac- and Rho-induced cytoskeletal reorganization. The Journal of Cell Biology. 138: 913-926.
Millarte, V. and H. Farhan. 2012. The Golgi in cell migration: regulation by signal transduction and its implications for cancer cell metastasis. The Scientific World Journal. 2012: 498278
Nethe, M. and P.L. Hordijk. 2011. A model for phospho-caveolin-1-driven turnover of focal adhesions. Cell Adhesion & Migration. 5: 59-64.
Ni, Y. and M.Y.M. Chiang. 2007. Cell morphology and migration linked to substrate rigidity. Soft Matter. 3: 1285.
NorthropS, J., A. Weber, M.S. Moosekern, C. Franzini-Armstrong, M.F. Bishop, G.R. Dubya, M. Tucker and T.P. Walsh. 1986. Different calcium dependence of the capping and cutting activities of villin. The Journal of Biological Chemistry. 261: 9274-9281.
Numata, T., T. Shimizu and Y. Okada. 2007. TRPM7 is a stretch- and swelling-activated cation channel involved in volume regulation in human epithelial cells. American Journal of Physiology. Cell Physiology. 292: C460-C467.
Ong, H.L. and I.S. Ambudkar. 2011. The dynamic complexity of the TRPC1 channelosome. Channels. 5: 424-431.
Pani, B., H.L. Ong, S.C. Brazer, X. Liu, K. Rauser, B.B. Singh and I.S. Ambudkar. 2009. Activation of TRPC1 by STIM1 in ER-PM microdomains involves release of the channel from its scaffold caveolin-1. Proceedings of the National Academy of Sciences of the United States of America. 106: 20087-20092
Pani, B., H.L. Ong, X. Liu, K. Rauser, I.S. Ambudkar and B.B. Singh. 2008. Lipid rafts determine clustering of STIM1 in endoplasmic reticulum-plasma membrane junctions and regulation of store-operated Ca2+ entry (SOCE). The Journal of Biological Chemistry. 283: 17333-17340.
Pani, B. and B.B. Singh. 2009. Lipid rafts/caveolae as microdomains of calcium signaling. Cell Calcium. 45: 625-633.
Prevarskaya, N., R. Skryma and Y. Shuba. 2011. Calcium in tumour metastasis: new roles for known actors. Nature Reviews. Cancer. 11: 609-618.
Ridley, A.J., M.A. Schwartz, K. Burridge, R.A. Firtel, M.H. Ginsberg, G. Borisy, J.T. Parsons and A.R. Horwitz. 2003. Cell migration: integrating signals from front to back. Science. 302: 1704-1709.
Rizzuto, R., D. De Stefani, A. Raffaello and C. Mammucari. 2012. Mitochondria as sensors and regulators of calcium signalling. Nature Reviews. Molecular Cell Biology. 13: 566-578.
Schram, K., R. Ganguly, E.K. No, X. Fang, F.S. Thong and G. Sweeney. 2011. Regulation of MT1-MMP and MMP-2 by leptin in cardiac fibroblasts involves Rho/ROCK-dependent actin cytoskeletal reorganization and leads to enhanced cell migration. Endocrinology. 152: 2037-2047.
Soboloff, J., B.S. Rothberg, M. Madesh and D.L. Gill. 2012. STIM proteins: dynamic calcium signal transducers. Nature Reviews. Molecular Cell Biology. 13: 549-565.
Stathopulos, P.B., L. Zheng, G.Y. Li, M.J. Plevin and M. Ikura. 2008. Structural and mechanistic insights into STIM1-mediated initiation of store-operated calcium entry. Cell. 135: 110-122.
Tan, J.L., J. Tien, D.M. Pirone, D.S. Gray, K. Bhadriraju and C.S. Chen. 2003. Cells lying on a bed of microneedles: an approach to isolate mechanical force. Proceedings of the National Academy of Sciences of the United States of America. 100: 1484-1489.
Vicente-Manzanares, M., X. Ma, R.S. Adelstein and A.R. Horwitz. 2009. Non-muscle myosin II takes centre stage in cell adhesion and migration. Nature Reviews. Molecular Cell Biology. 10: 778-790.
Vicente-Manzanares, M., D.J. Webb and A.R. Horwitz. 2005. Cell migration at a glance. Journal of Cell Science. 118: 4917-4919.
Watanabe, T., J. Noritake and K. Kaibuchi. 2005. Regulation of microtubules in cell migration. Trends in Cell Biology. 15: 76-83.
Wei, C., X. Wang, M. Chen, K. Ouyang, L.S. Song and H. Cheng. 2009. Calcium flickers steer cell migration. Nature. 457: 901-905.
Wei, C., X. Wang, M. Zheng and H. Cheng. 2012. Calcium gradients underlying cell migration. Current Opinion in Cell Biology. 24: 254-261.
Woodman, S.E., A.W. Ashton, W. Schubert, H. Lee, T.M. Williams, F.A. Medina, J.B. Wyckoff, T.P. Combs and M.P. Lisanti. 2003. Caveolin-1 knockout mice show an impaired angiogenic response to exogenous stimuli. The American Journal of Pathology. 162: 2059-2068.
Yang, S., J.J. Zhang and X.Y. Huang. 2009. Orai1 and STIM1 are critical for breast tumor cell migration and metastasis. Cancer Cell. 15: 124-134.
Young, C.L., A. Feierstein and F.S. Southwick. 1994. Calcium regulation of actin filament capping and monomer binding by macrophage capping protein. The Journal of Biological Chemistry. 269: 13997-14002.