High impact information on BARHL1

• Furthermore, the mapping assignment and the expression pattern make BARHL1 an attractive positional candidate gene for a form of Joubert syndrome, a rare developmental anomaly of the cerebellum in humans [1].
• In particular, Barhl1 showed specific domains of expression in the diencephalon and in the rhombencephalon where it was found to be expressed in migrating cells giving rise to the cerebellar external granular layer and to specific populations of dorsal sensory interneurons of the spinal cord [1].
• We isolated and sequenced the full-length mouse Barhl1 and mapped both the human BARHL1 and BARHL2 genes to chromosomes 9q34 and 1p22, respectively [1].
• We show here that Barhl1 exhibits a select expression pattern in the superior colliculus with positive neurons largely restricted to the zonal layer, as visualized by the beta-galactosidase activity expressed from the lacZ reporter knocked in the Barhl1 locus [2].
• Barhl1 is a homeodomain transcription factor that has been demonstrated to play an essential role in maintaining inner ear hair cells, cerebellar granule cells, and precerebellar neurons [2].

Biological context of BARHL1

• The BARHL1 gene, which localizes to chromosome 9q34 and has previously been proposed as a strong positional candidate gene for JS, was also investigated and excluded from involvement in JS that is linked to chromosome 9q34 [3].
• Detailed analysis of BARHL1 expression in fetal cerebellar cell layers using our new optic microscopy technology showed BARHL1 expression in external and internal granular cells and also in mouse adult granular cells, in agreement to Barhl1 null mouse phenotype affecting the differentiation and migration of granular cells [4].
• Targeted disruption of Barhl1 results in the loss of a large population of neurons from the zonal layer of the superior colliculus, as indicated by reduced beta-galactosidase staining and marker gene expression as well as by increased apoptotic cell death [2].

Anatomical context of BARHL1

• BARHL1 mRNA was found exclusively in the CNS restricted to p1-p4 prosomeres of the diencephalon, to the dorsal cells of the mesencephalon, to the dorsal dl1 sensory neurons of the spinal cord, and to the rhombic lips yielding the cerebellar anlage [4].
• Barhl1 is required for maintenance of a large population of neurons in the zonal layer of the superior colliculus [2].

Associations of BARHL1 with chemical compounds

• The N-terminus of BARHL1 protein presents two FIL domains and an acidic domain rich in serine/threonine and proline, while the C-terminus contains a canonical proline-rich domain [4].

Other interactions of BARHL1

• Mutational analysis of BARHL1 and BARX1 in three new patients with Joubert syndrome [5].

Analytical, diagnostic and therapeutic context of BARHL1

• Detailed analysis of the murine Barhl1 expression pattern by in situ hybridization revealed that this transcript is exclusively expressed in restricted domains of the developing CNS, which suggests that this gene, similar to its Drosophila counterparts BarH1 and BarH2, may play a crucial role in cell fate determination of neural structures [1].

References