Transcription factor Sp1

The protein encoded by this gene is a zinc finger transcription factor that binds to GC-rich motifs of many promoters. The encoded protein is involved in many cellular processes, including cell differentiation, cell growth, apoptosis, immune responses, response to DNA damage, and chromatin remodeling. post-translational modifications such as phosphorylation, acetylation, O-GlcNAcylation, and proteolytic processing significantly affect the activity of this protein, which can be an activator or a repressor. In the SV40 virus, Sp1 binds to the GC boxes in the regulatory sequence of the genome. == Structure ==

SP1 belongs to the Sp/KLF family of transcription factors. The protein is 785 amino acids long, with a molecular weight of 81 kDa. The SP1 transcription factor contains two glutamine-rich activation domains at its N-terminus that are believed to be necessary for promoter trans-activation. SP1 most notably contains three zinc finger protein motifs at its C-terminus, by which it binds directly to DNA and allows for interaction of the protein with other transcriptional regulators. Its zinc fingers are of the Cys2/His2 type and bind the consensus sequence 5'-(G/T)GGGCGG(G/A)(G/A)(C/T)-3' (GC box element). Some 12,000 SP-1 binding sites are found in the human genome. == Applications ==

Sp1 has been used as a control protein to compare with when studying the increase or decrease of the aryl hydrocarbon receptor and/or the estrogen receptor, since it binds to both and generally remains at a relatively constant level. Recently, a putative promoter region in FTMT, and positive regulators {SP1, cAMP response element-binding protein (CREB), and Ying Yang 1 (YY1)] and negative regulators [GATA2, forkhead box protein A1 (FoxA1), and CCAAT enhancer-binding protein b (C/EBPb)] of FTMT transcription have been identified (Guaraldo et al, 2016).The effect of DFP on the DNA-binding activity of these regulators to the FTMT promoter was examined using chromatin immunoprecipitation (ChIP) assay. Among the regulators, only SP1 displayed significantly increased DNA- binding activity following DFP treatment in a dose-dependent manner. SP1 knockdown by siRNA abolished the DFP-induced increase in the mRNA levels of FTMT, indicating SP1-mediated regulation of FTMT expression in the presence of DFP. Treatment with Deferiprone increased the expression of cytoplasmic and nuclear SP1 with predominant localization in the nucleus. == Inhibitors ==

Plicamycin, an antineoplastic antibiotic produced by Streptomyces plicatus, and Withaferin A, a steroidal lactone from Withania somnifera plant are known to inhibit Sp1 transcription factor. miR-375-5p microRNA significantly decreased expression of SP1 and YAP1 in colorectal cancer cells. SP1 and YAP1 mRNAs are direct targets of miR-375-5p. == Interactions ==

Transcription factor Sp1 has been shown to interact with: • AATF, • COL1A1, • E2F1, • FOSL1, • GABPA, • HDAC1, • HDAC2, • HMGA1, • HTT, • KLF6, • MEF2C, • MEF2D, • MSX1, • Myogenin, • POU2F1, • PPP1R13L, • PSMC5, • PML, • RELA, • SMAD3, • SUMO1, • SF1, • TAL1, • UBC. • WRN, • DDX3X == References ==