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Paired box protein Pax-6 also known as aniridia type II protein (AN2) or oculorhombin is a protein that in humans is encoded by the ''PAX6'' gene. Pax6 is a transcription factor present during embryonic development. The encoded protein contains two different binding sites that are known to bind DNA and function as regulators of gene transcription. It is a key regulatory gene of eye and brain development. Within the brain, the protein is involved in development of the specialized cells that process smell. As a transcription factor, Pax6 activates and/or deactivates gene expression patterns to ensure for proper development of the tissue. Mutations of the Pax6 gene are known to cause various disorders of the eyes. Two common disorders associated with a mutation are: aniridia, the absence of the iris, and Peter’s anomaly, thinning and clouding of the cornea. Scientists have created a “tae” model using mice during which time the mouse does not express Pax6. The "knockout” model is eyeless or has very underdeveloped eyes further indicating Pax6 is required for proper eye development.〔"Genes and Mapped Phenotypes." National Center for Biotechnology Information. U.S. Pax6 is a gene in prenatal development referred to as a transcription factor (activator and repressor). This means that Pax6 is a protein that binds to specific DNA sequences and activates or represses the genetic information delivered to mRNA. Pax6 is controlled by the signaling molecules Wnt1 and FGF8 and regulates eye, brain, and pancreas development. This gene is involved in patterning the midbrain. Nonsense mutations of Pax6 can lead to a condition called Aniridia which is associated with brain, olfactory, and pancreatic abnormalities. A study showed that progression of Aniridia can be stopped by application of a topical drug associated with this condition. National Library of Medicine, 12 Apr. 2014. Web. 14 Apr. 2014. "PAX6." Genetics Home Reference. U.S. National Library of Medicine, 7 Apr. 2014. Web. 14 Apr. 2014. "PAX6 in Sensory Development." Human Molecular Genetics. Oxford Journals, 15 May 2002. Web. 14 Apr. 2014. Shengxiu, Li, Dan Goldowitz, and Douglas J. Swanson. "The Requirement of Pax6 for Postnatal Eye Development: Evidence from Experimental Mouse Chimeras." Investigative Ophthalmology & Visual Science, 1 July 2007. Web. 14 Apr. 2014. Xie, Q., and D. Ung. "Gene Regulation by PAX6: Structural-functional Correlations of Missense Mutants and Transcriptional Control of Trpm3/miR-204." National Center for Biotechnology Information. U.S. National Library of Medicine, 6 Mar. 2014. Web. 14 Apr. 2014.〕 == Function == PAX6 is a member of the Pax gene family. It acts as a "master control" gene for the development of eyes and other sensory organs, certain neural and epidermal tissues as well as other homologous structures, usually derived from ectodermal tissues. However it has been recognized that a suite of genes is necessary for eye development, and therefore the term of "master control" gene may be inaccurate. This transcription factor is most noted for its use in the interspecifically induced expression of ectopic eyes and is of medical importance because heterozygous mutants produce a wide spectrum of ocular defects such as Aniridia in humans. Pax6 serves as a regulator in the coordination and pattern formation required for differentiation and proliferation to successfully take place, ensuring that the processes of neurogenesis and oculogenesis are carried out successfully. As a transcription factor, Pax6 acts at the molecular level in the signaling and formation of the central nervous system. The characteristic paired DNA binding domain of Pax6 utilizes two DNA-binding domains, the paired domain (PD), and the paired-type homeodomain (HD). These domains function separately via utilization by Pax6 to carry out molecular signaling that regulates specific functions of Pax6. An example of this lies in HD’s regulatory involvement in the formation of the lens and retina throughout oculogenesis contrasted by the molecular mechanisms of control exhibited on the patterns of neurogenesis in brain development by PD. The HD and PD domains act in close coordination, giving Pax6 its multifunctional nature in directing molecular signaling in formation of the CNS. Although many functions of Pax6 are known, the molecular mechanisms of these functions remain largely unresolved. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「PAX6」の詳細全文を読む スポンサード リンク
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