Noncoding RNAs, including long noncoding RNA (lncRNAs), micro RNAs and circular RNAs, are being recognized to play important roles in regulating nervous system development. We find that in the mammalian main olfactory system, the lncRNA H19 is one of th...

Highly-concentrated ion channels at axon initial segments (AIS) and nodes of Ranvier are necessary to initiate and regenerate action potentials in axons. The cytoskeletal protein β4-spectrin is proposed to stabilize voltage-gated sodium (Nav) channels a...

Axon growth is promoted by several extracellular signals, which activate a complex network of intracellular effectors including signaling cascades and cytoskeletal proteins at the growth cone that convey information to critical transcription factors in ...

Injury to the central nervous system (CNS) has severe consequences because adult CNS axons do not regenerate. PtdIns-3,4,5-P3 (PIP3) signaling is essential for axon growth during development of the nervous system. Silencing PIP3 phosphatase PTEN leads t...

How different classes of neurons integrate stochastic synaptic input has been a subject of intense experimental and theoretical focus over the last 50 years. Many approaches have approximated the cell as electrotonically compact and focussed on the effe...

The rapid and transient nature of action potential (AP)-induced transmitter release has led to the hypothesis that the rapid build up and dissipation of local intracellular calcium concentration near clusters of calcium channels acts as the trigger for release. We have applied spot-confocal fluorescence microscopy, a method with high spatial and temporal resolution, to characterise the properties of Ca2+ domains in ascending granule cell axons from cerebellar slices. The confocal detection volume was 260 nm in diameter, significantly smaller than the dimensions of the axon varicosities (1.2 x 0.7 µm; putative synaptic boutons). Whole-cell current clamp recording were made from GC cell bodies with pipettes solution containing 100-150 µM of the low-affinity calcium indicator Oregon Green Bapta 488-5N. A brief depolarising current pulse was used to activate APs at the soma, which, upon invasion of an axon varicosity, produced fluorescence transients that were variable in amplitude and time course. The largest...

Spinal cord injury (SCI) is a devastating condition that affects a quarter of a million individuals nationally and results in paralysis below the level of the injury. Chondroitin sulfate proteoglycans (CSPGs) are up-regulated by astrocytes in the glial scar following SCI and contribute to failed regeneration. To this end, we have engineered astrocytes to produce a modified form of the bacterial enzyme chondroitinase AC (ChAC), which can be secreted from mammalian cells. This enzyme normally cleaves and removes glycosaminoglycan (GAG) side chains from the CSPG protein core. Both in vitro and in vivo, such enzymatic GAG chain elimination enhances the ability of axons to ignore CSPG-induced inhibition and regenerate through the glial scar. Cultures of U373 human astrocytoma cells were transfected with adenovirus encoding ChAC and subsequently induced with doxycyclin to secrete ChAC. Conditioned media from these cultures was collected and concentrated at a minimum ratio of 25:1. In controlled experiments, chic...

Subsets of sensory neurons in mice express the glycan, lactosamine. The gene encoding an enzyme critical for synthesis of lactosamine was recently isolated. In situ hybridization reveals that this enzyme (β1-3-N-acetylglucosaminyltransferase-1 (β3GnT1) is expressed by sensory neurons in the olfactory epithelium, vomeronasal organ, on migrating GnRH neurons and on sensory neurons in cranial ganglia and dorsal root ganglia beginning at very early embryonic stages. Mice deficient in b3Gnt1 fail to express lactosamine during embryonic and early postnatal olfactory development and have severe defects in formation of connections between the olfactory epithelium and olfactory bulb at birth (Henion et al. 2005). We are interested in cell-cell interactions that involve surface glycans expressed either on growing axons or on migrating neurons that may play important roles in targeting axon pathfinding or migrating neurons. Interaction of endogenous carbohydrate binding proteins in the extracellular matrix or on cell...

Corticospinal motor neurons (CSMN) project from cortical layer V to target neurons in the spinal cord, and contribute critically to cortical control of motor function. CSMN degeneration is the CNS component of ALS/Lou Gehrig's disease, the central pathology in the related motor neuron diseases such as Heredity Spastic Paraplegia (HSP) and Primary Lateral Sclerosis (PLS), and CSMN injury contributes centrally to the loss of motor function in spinal cord injury. We developed in vitro approaches for direct investigation of cellular and molecular controls over CSMN differentiation, employing cultured CSMN isolated and purified by retrograde labeling and FACS. Here, we report that: 1) purified CSMN retain many elements of stereotypic morphology in vitro; 2) express specific markers for mature layer V neurons (MAP2, NF, ER81, Otx1); 3) express CSMN-specific markers (e.g. CTIP2); 4) lack markers that are specifically expressed by other projection neuron populations (e.g. LMO4). CSMN express IGF-1R and TrkB recept...

Regeneration of motor nerves is critical for the recovery of function in acute lesions and chronic neurodegenerative disorders such as Amyotrophic Lateral Sclerosis (ALS). However, degeneration and injury of sensory nerves, common to multiple chronic neuronal insults, has been more the target of pharmaceutical discovery and less attention has been directed to motor nerves. To identify small molecules capable of inducing motor axon growth, we treated postnatal rat spinal cord organotypic cultures with drugs from a library of 1040 Food and Drug Administration-approved drugs and nutritionals. Tissue cultures were incubated for 7 and 14 days with 10uM of each drug (n=10 cultures/drug), then collected and stained for neurofilament bearing axons with SMI-32. All cultures were blindly rated for axon outgrowth by qualitative and quantitative scales. Glial-derived neurotrophic factor (GDNF) treated cultures served as positive control, while DMSO treated cultures served as a vehicle control. All positive hits were r...