Transcription factor Sp8 also known as specificity protein 8 (SP-8) or Btd transcription factor (buttonhead)[5] is a protein that in humans is encoded by the SP8gene.[6][7] Sp8 is a transcription factor in the Sp/KLF family.
Function
Sp8 mediates limb outgrowth during early development.[5] Sp8 deletion in mice resulted in severe exencephaly.[8] Sp8 is a zinc-finger transcription factor. The structural difference between Sp8 and Sp9 is only one amino acid. These transcription factors are Apical Ectodermal Ridge (AER) specific in limb development. The Apical Ectodermal Ridge signaling is important for specification of distal limb structures. Sp8 and Sp9 mediate Fgf10 signaling, which in turn regulates Fgf8 expression (Fgf10→Fgf8). Fgf8 is essential for normal limb development, and without the presence of Fgf8 in early development, there would be a decreased length of the limb bud and possible failure of the limb tissue develop. Both Sp8 and Sp9 have been found in vertebrates. Although, so far only Sp8 has been proven to be present in invertebrates too. Under lab conditions, Sp8 replaced btd in Drosophila, showing that Sp8 and btd both have similar functions in limb development in both vertebrates and invertebrates. Gene knockdown in zebrafish displayed that Fgf8 expression is necessary for appendage development.[9]
^Kawakami Y, Esteban CR, Matsui T, Rodríguez-León J, Kato S, Izpisúa Belmonte JC (October 2004). "Sp8 and Sp9, two closely related buttonhead-like transcription factors, regulate Fgf8 expression and limb outgrowth in vertebrate embryos". Development. 131 (19): 4763–74. doi:10.1242/dev.01331. PMID15358670. S2CID1959276.
Further reading
Lee MT, Chen CH, Lee CS, Chen CC, Chong MY, Ouyang WC, Chiu NY, Chuo LJ, Chen CY, Tan HK, Lane HY, Chang TJ, Lin CH, Jou SH, Hou YM, Feng J, Lai TJ, Tung CL, Chen TJ, Chang CJ, Lung FW, Chen CK, Shiah IS, Liu CY, Teng PR, Chen KH, Shen LJ, Cheng CS, Chang TP, Li CF, Chou CH, Chen CY, Wang KH, Fann CS, Wu JY, Chen YT, Cheng AT (May 2011). "Genome-wide association study of bipolar I disorder in the Han Chinese population". Molecular Psychiatry. 16 (5): 548–56. doi:10.1038/mp.2010.43. PMID20386566. S2CID41746496.
Ravasi T, Suzuki H, Cannistraci CV, Katayama S, Bajic VB, Tan K, Akalin A, Schmeier S, Kanamori-Katayama M, Bertin N, Carninci P, Daub CO, Forrest AR, Gough J, Grimmond S, Han JH, Hashimoto T, Hide W, Hofmann O, Kamburov A, Kaur M, Kawaji H, Kubosaki A, Lassmann T, van Nimwegen E, MacPherson CR, Ogawa C, Radovanovic A, Schwartz A, Teasdale RD, Tegnér J, Lenhard B, Teichmann SA, Arakawa T, Ninomiya N, Murakami K, Tagami M, Fukuda S, Imamura K, Kai C, Ishihara R, Kitazume Y, Kawai J, Hume DA, Ideker T, Hayashizaki Y (March 2010). "An atlas of combinatorial transcriptional regulation in mouse and man". Cell. 140 (5): 744–52. doi:10.1016/j.cell.2010.01.044. PMC2836267. PMID20211142.
