Brain-specific homeobox
{{short description|Protein encoded by the BSX gene}}
Brain-specific homeobox is a protein that in humans is encoded by the BSX gene.{{cite web | title = Entrez Gene: BSX brain-specific homeobox| url = https://www.ncbi.nlm.nih.gov/gene/390259}}
Structure and expression pattern
Bsx is an evolutionarily highly-conserved homeodomain-containing transcription factor that belongs to the ANTP-class.{{cite journal |last1=Ferrier |first1=David E. K. |title=Evolution of Homeobox Gene Clusters in Animals: The Giga-Cluster and Primary vs. Secondary Clustering |journal=Frontiers in Ecology and Evolution |date=14 April 2016 |volume=4 |doi=10.3389/fevo.2016.00036|doi-access=free |hdl=10023/8685 |hdl-access=free }} In mouse it has been shown to be expressed in the telencephalic septum, pineal gland, the mammillary bodies and arcuate nucleus.{{cite journal |last1=Cremona |first1=M |last2=Colombo |first2=E |last3=Andreazzoli |first3=M |last4=Cossu |first4=G |last5=Broccoli |first5=V |title=Bsx, an evolutionary conserved Brain Specific homeoboX gene expressed in the septum, epiphysis, mammillary bodies and arcuate nucleus. |journal=Gene Expression Patterns |date=January 2004 |volume=4 |issue=1 |pages=47–51 |pmid=14678827|doi=10.1016/S1567-133X(03)00151-0 }}
Function in the hypothalamus
In the hypothalamic arcuate nucleus, Bsx has been demonstrated to be necessary for normal expression levels of the two orexigenic neuropeptides Agouti-related peptide and Neuropeptide Y.{{cite journal |last1=Sakkou |first1=M |last2=Wiedmer |first2=P |last3=Anlag |first3=K |last4=Hamm |first4=A |last5=Seuntjens |first5=E |last6=Ettwiller |first6=L |last7=Tschöp |first7=MH |last8=Treier |first8=M |title=A role for brain-specific homeobox factor Bsx in the control of hyperphagia and locomotory behavior. |journal=Cell Metabolism |date=June 2007 |volume=5 |issue=6 |pages=450–63 |doi=10.1016/j.cmet.2007.05.007 |pmid=17550780|doi-access=free }}
Function in the pineal gland
In the pineal gland of the clawed frog Xenopus, Bsx is expressed following the circadian rhythm and controls photoreceptor cell differentiation.{{cite journal |last1=D'Autilia |first1=S. |last2=Broccoli |first2=V. |last3=Barsacchi |first3=G. |last4=Andreazzoli |first4=M. |title=Xenopus Bsx links daily cell cycle rhythms and pineal photoreceptor fate |journal=Proceedings of the National Academy of Sciences |date=22 March 2010 |volume=107 |issue=14 |pages=6352–6357 |doi=10.1073/pnas.1000854107|pmid=20308548 |pmc=2852004 |bibcode=2010PNAS..107.6352D |doi-access=free }} In zebrafish Bsx is required for normal development of all cell types within the pineal gland, including melatonin-releasing pinealocytes, photoreceptor cells and leftwards migrating parapineal cells,{{cite journal |last1=Schredelseker |first1=Theresa |last2=Driever |first2=Wolfgang |title=Bsx controls pineal complex development |journal=Development |date=1 July 2018 |volume=145 |issue=13 |pages=dev163477 |doi=10.1242/dev.163477|pmid=29945867 |doi-access=free }} which in zebrafish are crucial for the establishment of brain asymmetry.{{cite journal |last1=Duboc |first1=Véronique |last2=Dufourcq |first2=Pascale |last3=Blader |first3=Patrick |last4=Roussigné |first4=Myriam |title=Asymmetry of the Brain: Development and Implications |journal=Annual Review of Genetics |date=23 November 2015 |volume=49 |issue=1 |pages=647–672 |doi=10.1146/annurev-genet-112414-055322|pmid=26442849 }}