Disease relevance of Efnb3

• Cochlear nerve ganglion cells expressed ephrin-B2, and the modiolus expressed mRNA coding for ephrin-B3, both transmembrane ligands for EphA4 [1].

High impact information on Efnb3

• Ephrin-B3 is the midline barrier that prevents corticospinal tract axons from recrossing, allowing for unilateral motor control [2].
• We report that in ephrin-B3(-/-) mice, corticospinal tract projections freely recross in the spinal gray matter, such that the motor cortex on one side of the brain now provides bilateral input to the spinal cord [2].
• We demonstrate that ephrin-B3 is expressed in postnatal myelinating oligodendrocytes and, by using primary CNS neurons, show that ephrin-B3 accounts for an inhibitory activity equivalent to that of the other three myelin-based inhibitors, acting through p75, combined [3].
• Ephrin-B3 is a myelin-based inhibitor of neurite outgrowth [3].
• Elk-L3, a novel transmembrane ligand for the Eph family of receptor tyrosine kinases, expressed in embryonic floor plate, roof plate and hindbrain segments [4].

Biological context of Efnb3

• The Elk-L3 gene has been localized to mouse chromosome 11 and human chromosome 17 [4].
• Intron/exon borders and number of exons are almost identical to those in the mouse ELF3 gene [5].

Anatomical context of Efnb3

• In mice, ephrin-B3 functions during development as a midline repellant for axons of the corticospinal tract [3].
• In this study, we examined inner ears from ephrin-B3 homozygous and ephrin-B2 heterozygous mice [6].
• Neither the midline guidance errors nor excessive numbers of FTC axons were observed in the spinal cords of ephrin-B3(lacz) mice that express a truncated form of ephrin-B3, which is capable of forward but not reverse signaling [7].
• Elk-L3 is notable for its remarkably restricted and prominent expression in the floor plate and roof plate of the developing neural tube and its rhombomere-specific expression in the developing hindbrain [4].
• The EphB receptors are expressed in the hippocampus, and the ligand, ephrin-B3, is transcribed in the lateral septum, the major subcortical target of hippocampal neurons [8].

Regulatory relationships of Efnb3

• EphB receptors and ephrin-B3 regulate axon guidance at the ventral midline of the embryonic mouse spinal cord [7].

Other interactions of Efnb3

• A recently identified third transmembrane-type ligand, Elf3, specifically, but weakly, binds Cek10 and only induces focus formation when activated by C-terminal truncation [9].
• EphBs are expressed in a D-V gradient, ephrin-B1 in a L-M gradient in SC, and ephrin-B3 at its midline [10].

Analytical, diagnostic and therapeutic context of Efnb3

• In situ hybridization of mouse embryos showed ephrin-B3 is expressed prominently at the dorsal and ventral midline of the neural tube, particularly in the floor plate, a structure with key functions in patterning the nervous system [11].

References