Doublecortin and JIP3 are neural-specific counteracting regulators of dynein-mediated retrograde trafficking.

Mutations in the microtubule (MT)-binding protein doublecortin (DCX) or in the MT-based molecular motor dynein result in lissencephaly. However, a functional link between DCX and dynein has not been defined. Here, we demonstrate that DCX negatively regulates dynein-mediated retrograde transport in neurons from or mice by reducing dynein's association with MTs and disrupting the composition of the dynein motor complex.

Dual Role of Rbpj in the Maintenance of Neural Progenitor Cells and Neuronal Migration in Cortical Development.

The development of the cerebral cortex is directed by a series of methodically precise events, including progenitor cell proliferation, neural differentiation, and cell positioning. Over the past decade, many studies have demonstrated the critical contributions of Notch signaling in neurogenesis, including that in the developing telencephalon. However, in vivo evidence for the role of Notch signaling in cortical development still remains limited partly due to the redundant functions of four mammalian Notch paralogues and embryonic lethality of the knockout mice.

An Implantable Micro-Caged Device for Direct Local Delivery of Agents.

Local and controlled delivery of therapeutic agents directly into focally afflicted tissues is the ideal for the treatment of diseases that require direct interventions. However, current options are obtrusive, difficult to implement, and limited in their scope of utilization; the optimal solution requires a method that may be optimized for available therapies and is designed for exact delivery. To address these needs, we propose the Biocage, a customizable implantable local drug delivery platform.

Genome-wide profiling of differentially spliced mRNAs in human fetal cortical tissue exposed to alcohol.

Excessive alcohol consumption results in significant changes in gene expression and isoforms due to altered mRNA splicing. As such, an intriguing possibility is that disturbances in alternative splicing are involved in key pathological pathways triggered by alcohol exposure. However, no resources have been available to systematically analyze this possibility at a genome-wide scale.

Variations in brain defects result from cellular mosaicism in the activation of heat shock signalling.

Repetitive prenatal exposure to identical or similar doses of harmful agents results in highly variable and unpredictable negative effects on fetal brain development ranging in severity from high to little or none. However, the molecular and cellular basis of this variability is not well understood. This study reports that exposure of mouse and human embryonic brain tissues to equal doses of harmful chemicals, such as ethanol, activates the primary stress response transcription factor heat shock factor 1 (Hsf1) in a highly variable and stochastic manner.

Proteome dynamics during postnatal mouse corpus callosum development.

Formation of cortical connections requires the precise coordination of numerous discrete phases. This is particularly significant with regard to the corpus callosum, whose development undergoes several dynamic stages including the crossing of axon projections, elimination of exuberant projections, and myelination of established tracts. To comprehensively characterize the molecular events in this dynamic process, we set to determine the distinct temporal expression of proteins regulating the formation of the corpus callosum and their respective developmental functions.

Ephrin-A5 Is Required for Optimal Fertility and a Complete Ovulatory Response to Gonadotropins in the Female Mouse.

Follicle growth and ovulation involve the coordinated expression of many genes, driven by FSH and LH. Reports indicate that Eph receptors and ephrins are expressed in the ovary, suggesting roles in follicle growth and/or ovulation. We previously reported FSH-induced expression of ephrin-A5 (EFNA5) and 4 of its cognate Eph receptors in mouse granulosa cells.

Breakdown of interlocking domains may contribute to formation of membranous globules and lens opacity in ephrin-A5(-/-) mice.

Ephrin-A5, a ligand of the Eph family of receptor tyrosine kinases, plays a key role in lens fiber cell packing and cell-cell adhesion, with approximately 87% of ephrin-A5(-/-) mice develop nuclear cataracts. Here, we investigated the extensive formation of light-scattering globules associated with breakdown of interlocking protrusions during lens opacification in ephrin-A5(-/-) mice. Lenses from wild-type (WT) and ephrin-A5(-/-) mice between 2 and 21 weeks old were studied with light and electron microscopy, immunofluorescence labeling, freeze-fracture TEM and filipin cytochemistry for membrane cholesterol detection.

EphA4 has distinct functionality from EphA7 in the corticothalamic system during mouse brain development.

Deciphering the molecular basis for guiding specific aspects of neocortical development remains a challenge because of the complexity of histogenic events and the vast array of protein interactions mediating these events. The Eph family of receptor tyrosine kinases is implicated in a number of neurodevelopmental activities. Eph receptors have been known to be capable of responding to several ephrin ligands within their subgroups, often eliciting similar downstream effects.

Formation of persistent hyperplastic primary vitreous in ephrin-A5-/- mice.

Purpose: Primary vitreous regression is a critical event in mammalian eye development required for proper ocular maturity and unhindered vision. Failure of this event results in the eye disease persistent hyperplastic primary vitreous (PHPV), also identified as persistent fetal vasculature (PFV), a condition characterized by the presence of a fibrovascular mass adjacent to the lens and retina, and associated with visual disability and blindness. Here, we identify ephrin-A5 to be a critical regulator for primary vitreous regression.

Cryosectioning.

Cryosectioning, the sectioning of frozen specimens, has been an important histological tool for more than a century and continues to be extensively utilized today. However, the ability to produce high-quality sections is often a difficult process requiring extensive patience and experience. In this chapter, we have detailed an effective method for the embedding, mounting, and sectioning of frozen tissues, as well as have provided suggestions in producing high-quality sections.

Growth cone collapse assay.

Growth cone collapse is an easy and efficient test for detecting and characterizing axon guidance activities secreted or expressed by cells. It can also be used to dissect signaling pathways by axon growth inhibitors and to isolate therapeutic compounds that promote axon regeneration. Here, we describe a growth cone collapse assay protocol used to study signal transduction mechanisms of the repulsive axon guidance molecule ephrin-A5 in hippocampal neurons.

Further analysis of the lens of ephrin-A5-/- mice: development of postnatal defects.

Purpose: The cells of the mammalian lens must be carefully organized and regulated to maintain clarity. Recent studies have identified the Eph receptor ligand ephrin-A5 as a major contributor to lens development, as mice lacking ephrin-A5 develop abnormal lenses, resulting in cataracts. As a follow-up to our previous study on the cataracts observed in ephrin-A5(-/-) animals, we have further examined the morphological and molecular changes in the ephrin-A5(-/-) lens.

Roles of EphA2 in Development and Disease.

The Eph family of receptor tyrosine kinases (RTKs) has been implicated in the regulation of many aspects of mammalian development. Recent analyses have revealed that the EphA2 receptor is a key modulator for a wide variety of cellular functions. This review focuses on the roles of EphA2 in both development and disease.

The role of Eph receptors in lens function and disease.

Cataract is the single largest contributor to blindness in the world, with the disease having a strong genetic component. In recent years the Eph family of receptor tyrosine kinases has been identified as a key regulator in lens clarity. In this review we discuss the roles of the Eph receptors in lens biology and cataract development.

Human cataract mutations in EPHA2 SAM domain alter receptor stability and function.

The cellular and molecular mechanisms underlying the pathogenesis of cataracts leading to visual impairment remain poorly understood. In recent studies, several mutations in the cytoplasmic sterile-α-motif (SAM) domain of human EPHA2 on chromosome 1p36 have been associated with hereditary cataracts in several families. Here, we have investigated how these SAM domain mutations affect EPHA2 activity.

Loss of ephrin-A5 function disrupts lens fiber cell packing and leads to cataract.

Cell-cell interactions organize lens fiber cells into highly ordered structures to maintain transparency. However, signals regulating such interactions have not been well characterized. We report here that ephrin-A5, a ligand of the Eph receptor tyrosine kinases, plays a key role in lens fiber cell shape and cell-cell interactions.