Sp1為廣泛性的調控體內許多基因的轉錄因子，許多研究指出與細胞增生和調控細胞生長週期相關。在腦中風缺血的情況下，大部分神經細胞會受到傷害而走向死亡的路徑，先前文獻指出缺血的環境導致神經細胞死亡可經由凋亡的途徑，另外一些報導指出給予神經細胞低滲透壓或是缺血性腦中風動物造成的傷害，能增加Sp1的表現量，進而表現下游基因，而近年來也有文獻指出在缺氧狀態下，Sp1能增加某些基因的表現，像是COX-2、VEGF，而我們也觀察到神經細胞在缺氧的狀態下處理之後，Sp1隨時間延長有增加的表現，於是我們進一步使用體外缺糖缺氧方式處理初代培養的神經細胞，模擬體內缺血狀態，在處理後隨時間的增加，由西方點墨法觀察Sp1有增加的表現，但是在神經膠細胞卻看不到Sp1顯著的表現增加，利用RT-PCR方式發現mRNA表現量也受缺糖缺氧壓力增加，但Sp1在蛋白質量上的增加遠大於轉錄過程所造成的增加，進一步以CHX抑制轉譯作用，發現在OGD壓力下Sp1表現的增加是由於Sp1穩定性增加所導致，最後以MTS測試推測Sp1在缺糖缺氧壓力下蛋白質穩定性的增加有保護神經細胞的作用。

Sp1 is a ubiquitous transcription factor which is considered constitutively regulating numerous gene expressions. Previous investigation indicated that Sp1 DNA-binding activity is increased in hypoxia condition and regulate gene expression, such as COX-2 and VEGF. Recent studies said that increase pf Sp1 was evident at 1 h and was more prominent at 3 h after middle cerebral artery occlusion (MCAO), especially in large neuron-like cells. Apoptotic cell death pathways have also been implicated in ischemic cerebral injury in ischemia animal models. It is still not clear whether Sp1 plays any role in cerebral ischemia injury. Here, we use oxygen glucose deprivation (OGD) in primary culture as an in vitro ischemia model. We found that expression of Sp1 was increased in neuronal cells after OGD treatment, but not in glial cells. However, the Sp1 upregulation is mostly contributed to the hypoxia condition. The RT-PCR data indicated that the increasing of Sp1 does not due to transcriptional control. Furthermore, we use cycloheximide, which is a translational inhibitor, and discovered that the increase Sp1 protein expression after OGD is due to Sp1 protein stability increases. We also found that Sp1 increase play a positive role after OGD stress.

Abramov, A. Y., Scorziello, A. , and Duchen, M. R. Three Distinct Mechanisms Generate Oxygen Free Radicals in Neurons and Contribute to Cell Death during Anoxia and Reoxygenation. The Journal of Neuroscience, 27, 1129 –1138. (2007)
Athanikar, J. N., Sanchez, H.B., and Osborne, T.F. Promoter selective transcriptional synergy mediated by sterol regulatory element binding protein and Sp1: a critical role for the Btd domain of Sp1. Mol. Cell Biol. , 17, 5193–5200. (1997)
Azizkhan, J. C., Jensen, D.E., Pierce, A.J., Wade, M. Transcription from TATA-less promoters: dihydrofolate reductase as a model. Crit. Rev. Eukaryot. Gene Expr., 3, 229-254. (1993)
Barone, F. C., Feuerstein, G.Z. Inflammatory mediators and stroke: new opportunities for novel therapeutics (review). J Cereb Blood Flow Metab., 15, 819–834. (1999)
Bouwman, P. and Philipsen, S. Regulation of the activity of Sp1-related transcription factors. Mol. Cell. Endocrinol., 195, 27-38. (2002)
Brewer, G. J., Torricelli, J.R., Evege, E.K., Price, P.J. Optimized survival of hippocampal neurons in B27-supplemented neurobasalTM, a new serum-free medium combination. J. Neurosci. Res., 35, 567-576 (1993)
Chang, W. C., Chen,B.K. Transcription factor Sp1 functions as an anchor protein in gene transcription of human 12(S)-lipoxygenase. Biochem Biophys Res Commun. , 338, 117-121. (2005)
Cummins, E. P., Taylorr, C. T. Hypoxia-responsive transcription factors. Eur J Physiol, 450, 363–371. (2005)
Dirnagl, U., Iadecola, C. and Moskowitz, M. A. . (1999). Pathobiology of ischaemic stroke: an integrated view. Trends Neurosci. , 22, 391–397.
Dynan, W. S., Tjian, R. The promoter-specific transcription factor Sp1 binds to upstream sequences in the SV40 early promoter. Cell, 35, 79-87. (1983)
Grinstein, E., Jundt,F., Weinert, I. , Wernet, P and Royer,H.D. Sp1 as G1 cell cycle phase specific transcription factor in epithelial cells. Oncogene 21, 1485 - 1492. (2002)
Inta, I., Paxia,S., Maegele, I. ,Zhang, W. ,Pizzi, M. ,Spano,P.F. ,Sarnico, I. , Muhammad, S. , Herrmann, O. , Inta ,D. , Baumann, B. , Liou, H.C. , Schmid, R. M. , and Schwaninger, M. Bim and Noxa Are Candidates to Mediate the Deleterious Effect of the NF- B Subunit RelA in Cerebral Ischemia. The Journal of Neuroscience, 26, 12896 –12903. (2006)
Kadonaga, J. T., Carner,K.R., Masiarz,F.R. and Tjian,R. Isolation of cDNA encoding transcription factor Sp1 and functional analysis of the DNA binding domain. Cell, 51, 1079–1090. (1987)
Kang, H. T., Ju, J. W., Cho, J. W. and Hwang E. S. Down-regulation of Sp1 Activity through Modulation of O-Glycosylation by Treatment with a Low Glucose Mimetic, 2-Deoxyglucose. J Biol Chem 278, 51223–51231. (2003)
Koistinaho, J., Hokfelt, T. Altered gene expression in brain ischemia. Neuroreport 8, i–viii. (1997)
Lavrovskya, Y., Chatterjeea, B. , Clarkb,R.A. , Roya, A.K. Role of redox-regulated transcription factors in inflammation, aging and age-related diseases. Experimental Gerontology 35, 521–532. (2000)
Lee, J., Kosaras, B. ,Aleyasin, H. ,Han, J. A. ,Park, D. S., Ratan R.R., Kowall, N.W., Ferrante, R. J., Lee, S. W. and Ryu, H. Role of cyclooxygenase-2 induction by transcription factor Sp1 and Sp3 in neuronal oxidative and DNA damage response. The FASEB Journal, 20, 1657-2377. (2006)
Lee, M., Bikram, M., Oh, S. , Bull, D.A., Kim, S.W. Sp1-dependent regulation of the RTP801 promoter and its application to hypoxia-inducible VEGF plasmid for ischemic disease. Pharm Res, 21, 736–741. (2004 )
Li, L., Shihua He, Jian-Min Sun, and James R. Davie. Gene regulation by Sp1 and Sp3. Biochem. Cell Biol. , 82, 460–471. (2004)
Li, T., Chen, Y.H., Liu, T.J., Jia, J., Hampson, S., Shan, Y.X., Kibler,D. , Wang, P. H. Using DNA microarray to identify Sp1 as a transcriptional regulatory element of insulin-like growth factor 1 in cardiac muscle cells. Circ. Res, 93, 1202–1209. (2003)
Mao, X., Yang, S.H., Simpkins, J. W. and Barger, S.W. Glutamate receptor activation evokes calpain-mediated degradation of Sp3 and Sp4, the prominent Sp-family transcription factors in neurons. Journal of Neurochemistry, 100, 1300–1314. (2007)
Mastrangelo, I. A., Courey, A.J., Wall, J. S. , Jackson,S. P. and Hough, P. V. DNA looping and Sp1 multimer links: a mechanism for transcriptional synergism and enhancement. Proc Natl Acad Sci U S A., 88, 5670–5674. (1991)
Mattson, M. P., Culmsee, C., Yu, Z. F. Apoptotic and antiapoptotic mechanisms in stroke. Cell Tissue Res, 301, 173–187. (2000)
Nakayama, M., Uchimura, K., Lizhu, R. , Nagayama,T. , Rose, M. E., Stetler, R. A., Isakson ,P.C., Chen, J. and Graham, S.H. Cyclooxygenase-2 inhibition prevents delayed death of CA1 hippocampal neurons following global ischemia. Proc. Natl. Acad. Sci. USA, 95 10954–10959. (1998)
Philipsen, S. a. S., G. A tale of three fingers: the family ofmammalian Sp/XKLF transcription factors. Nucleic Acids Research, 27, 2991–3000. (1999)
Pugh, B.F. and Tjian, R. Mechanism of transcriptional activation by Sp1: Evidence for coactivators. Cell, 61, 1187-1197. (1990)
Ramos, A., Ho,W.C. , Forte, S. ,Dickson, K. , Boutilier, J. , Favell, K. and Barker, P.A. Hypo-Osmolar Stress Induces p75NTR Expression by Activating Sp1-Dependent Transcription. The Journal of Neuroscience, 27, 1498-1506. (2007)
Roos, M. D., Su, K., Baker, J.R., and Kudlow, J.E. O-glycosylation of an Sp1-derived peptide blocks known Sp1 protein interactions Mol. Cell Biol., 17, 6472–6480. (1997)
Ryu, H., Lee, J., Zaman, K., Kubilis J., Ferrante, R. J., Ross, B.D., Neve R. and Ratan, R.R. Sp1 and Sp3 Are Oxidative Stress-Inducible, Antideath Transcription Factors in Cortical Neurons. The Journal of Neuroscience, 23, 3597-3606. (2003)
Safe, S., Abdelrahim, M. Sp transcription factor family and its role in cancer. European Journal of Cancer, 41, 2438–2448. (2005)
Sanchez-Elsner, T., Ramirez, J.R., Sanz-Rodriguez, F., Varela, E., Bernabeu, C., Botella, L.M. A cross-talk between hypoxia and TGF-b orchestrates erythropoietin gene regulation through Sp1 and Smads. J Mol Biol 336, 9–24. (2004)
Schaëfer, D., Hamm-Kuënzelmann, B., Brand, K. Glucose regulates the promoter activity of aldolase A and pyruvate kinase M2 via dephosphorylation of Sp1. FEBS Letters 417, 325-328. (1997)
Simard, J. M., Chen, M., Tarasov, K. V., Bhatta, S., Ivanova, S., Melnitchenko, L., Tsymbalyuk, N., West, G. A. and Gerzanich, V. Newly expressed SUR1-regulated NCCa-ATP channel mediates cerebral edema after ischemic stroke. Nature medicine, 12, 433-440. (2006)
Tabakman, R., Jiang, H.,Shahr, I., Arien-zakay, H., Levine, R. A. and Lazarovici, P. Neuroprotection by NGF in the PC12 In Vitro OGD Model. Ann. N.Y. Acad. Sci., 1053, 84-96. (2005)
Tate, P., Skarnes,W. and Bird,A. The methyl-CpG binding protein MeCP2 is essential for embryonic development in the mouse. Nature Genet. , 12, 205–208. (1996)
Wong, W. K., Chen, K., and Shih, J.C. Decreased methylation and transcription repressor Sp3 up-regulated human monoamine oxidase (MAO) B expression during Caco-2 differentiation. J Biol Chem 278, 36227–36236 36235. (2003)
Xu, Q., Ji, Y.S., Schmedtje J.F. Jr. Sp1 increases expression of cyclooxygenase-2 in hypoxic vascular endothelium Implications for the mechanisms of aortic aneurysm and heart failure. J Biol Chem 275, 24583–24589. (2000)
Yang, X., Su, K. , Roos, M. D. , Chang, Q. , Paterson, A. J. , and Kudlow, J. E. O-linkage of N-acetylglucosamine to Sp1 activation domain inhibits its transcriptional capability. Proc. Natl. Acad. Sci. U.S.A. , 98, 6611-6616. (2001)
Yieh, L., Sanchez, H.B., and Osborne, T.F. Domains of transcription factor Sp1 required for synergistic activation with sterol regulatory element binding protein 1 of low density lipoprotein receptor promoter. Proc. Natl. Acad. Sci. U.S.A., 92, 6102–6106. (1995)
Yu, B., Datta, P. K. and Bagchi, S. Stability of the Sp3-DNA complex is promoterspecific: Sp3 efficiently competes with Sp1 for binding to promoters containing multiple Sp-sites. Nucleic Acids Research, 31, 5368-5376. (2003)
Zhang, F., Su,K., Yang,X. , Bowe,D. B. ,Paterson, A. J. and Kudlow, J. E. O-GlcNAc Modification Is an Endogenous Inhibitor of the Proteasome. Cell, 115, 715–725. (2003)
Zheng, Z., Lee, J. E. and Yenari, M.A. Stroke: Molecular Mechanisms and Potential Targets for Treatment. Current Molecular Medicine 3, 361-372. (2003)