Mark J Henkemeyer

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We report that the many Eph-related receptor tyrosine kinases, and their numerous membrane-bound ligands, can each be grouped into only two major specificity subclasses. Receptors in a given subclass bind most members of a corresponding ligand subclass. The physiological relevance of these groupings is suggested by viewing the collective distributions of(More)
In animals with binocular vision, retinal ganglion cell (RGC) axons either cross or avoid the midline at the optic chiasm. Here, we show that ephrin-Bs in the chiasm region direct the divergence of retinal axons through the selective repulsion of a subset of RGCs that express EphB1. Ephrin-B2 is expressed at the mouse chiasm midline as the ipsilateral(More)
Eph family receptor tyrosine kinases have been proposed to control axon guidance and fasciculation. To address the biological functions of the Eph family member Nuk, two mutations in the mouse germline have been generated: a protein null allele (Nuk1) and an allele that encodes a Nuk-beta gal fusion receptor lacking the tyrosine kinase and C-terminal(More)
Experiments in amphibians have implicated fibroblast growth factors (FGFs) in the generation and patterning of mesoderm during embryogenesis. We have mutated the gene for fibroblast growth factor receptor 1 (fgfr-1) in the mouse to genetically dissect the role of FGF signaling during development. In the absence of fgfr-1 signaling, embryos displayed early(More)
Sek4 and Nuk are members of the Eph-related family of receptor protein-tyrosine kinases. These receptors interact with a set of cell surface ligands that have recently been implicated in axon guidance and fasciculation. We now demonstrate that the formation of the corpus callosum and anterior commissure, two major commissural axon tracts that connect the(More)
We report that EphB receptors direct unique axonal behaviors required for mapping the dorsal-ventral (D-V) retinal axis along the lateral-medial (L-M) axis of the superior colliculus (SC). EphBs are expressed in a D-V gradient, ephrin-B1 in a L-M gradient in SC, and ephrin-B3 at its midline. EphBs and ephrin-Bs are expressed in countergradients in retina(More)
Eph-related receptor tyrosine kinases have been implicated in the control of axonal navigation and fasciculation. To investigate the biochemical mechanisms underlying such functions, we have expressed the EphB2 receptor (formerly Nuk/Cek5/Sek3) in neuronal NG108-15 cells, and have observed the tyrosine phosphorylation of multiple cellular proteins upon(More)
Receptor tyrosine kinases of the EPH class have been implicated in the control of axon guidance and fasciculation, in regulating cell migration, and in defining compartments in the developing embryo. Efficient activation of EPH receptors generally requires that their ligands be anchored to the cell surface, either through a transmembrane (TM) region or a(More)
A Drosophila gene (drk) encodes a widely expressed protein with a single SH2 domain and two flanking SH3 domains, which is homologous to the Sem-5 protein of C. elegans and mammalian GRB2. Genetic analysis suggests that drk function is essential for signaling by the sevenless receptor tyrosine kinase. Drk biological activity correlates with binding of its(More)
Here, using a genetic approach, we dissect the roles of EphB receptor tyrosine kinases in dendritic spine development. Analysis of EphB1, EphB2, and EphB3 double and triple mutant mice lacking these receptors in different combinations indicates that all three, although to varying degrees, are involved in dendritic spine morphogenesis and synapse formation(More)