Amphiphilic peptide-tagged N-cadherin forms radial glial-like fibers that enhance neuronal migration in injured brain and promote sensorimotor recovery.

The mammalian brain has very limited ability to regenerate lost neurons and recover function after injury. Promoting the migration of young neurons (neuroblasts) derived from endogenous neural stem cells using biomaterials is a new and promising approach to aid recovery of the brain after injury. However, the delivery of sufficient neuroblasts to distant injured sites is a major challenge because of the limited number of scaffold cells that are available to guide neuroblast migration. To address this issue, we have developed an amphiphilic peptide [(RADA)3-(RADG)] (mRADA)-tagged N-cadherin extracellular domain (Ncad-mRADA), which can remain in mRADA hydrogels and be injected into deep brain tissue to facilitate neuroblast migration. Migrating neuroblasts directly contacted the fiber-like Ncad-mRADA hydrogel and efficiently migrated toward an injured site in the striatum, a deep brain area. Furthermore, application of Ncad-mRADA to neonatal cortical brain injury efficiently promoted neuronal regeneration and functional recovery. These results demonstrate that self-assembling Ncad-mRADA peptides mimic both the function and structure of endogenous scaffold cells and provide a novel strategy for regenerative therapy.

Centrosomin represses dendrite branching by orienting microtubule nucleation.

Neuronal dendrite branching is fundamental for building nervous systems. Branch formation is genetically encoded by transcriptional programs to create dendrite arbor morphological diversity for complex neuronal functions. In Drosophila sensory neurons, the transcription factor Abrupt represses branching via an unknown effector pathway. Targeted screening for branching-control effectors identified Centrosomin, the primary centrosome-associated protein for mitotic spindle maturation. Centrosomin repressed dendrite branch formation and was used by Abrupt to simplify arbor branching. Live imaging revealed that Centrosomin localized to the Golgi cis face and that it recruited microtubule nucleation to Golgi outposts for net retrograde microtubule polymerization away from nascent dendrite branches. Removal of Centrosomin enabled the engagement of wee Augmin activity to promote anterograde microtubule growth into the nascent branches, leading to increased branching. The findings reveal that polarized targeting of Centrosomin to Golgi outposts during elaboration of the dendrite arbor creates a local system for guiding microtubule polymerization.

The Efficiency of a Modified Real-time Wireless Brain Electric Activity Calculator to Reveal the Subliminal Psychological Instability of Surgeons that Possibly Leads to Errors in Surgical Procedures.

We know that experienced endoscopic surgeons, despite having extensive training, may make a rare but fatal mistake. Prof. Takeshi Ohdaira developed a device visualizing brain action potential to reflect the latent psychological instability of the surgeon. The Ohdaira system consists of three components: a real-time brain action potential measurement unit, a simulated abdominal cavity, and an intra-abdominal monitor. We conducted two psychological stress tests by using an artificial laparoscopic simulator and an animal model. There were five male subjects aged between 41 to 61 years. The psychological instability scores were considered to reflect, to some extent, the number of years of experience of the surgeon in medical care. However, very high inter-individual variability was noted. Furthermore, we discovered the following: 1) bleeding during simulated laparoscopic surgery--an episode generally considered to be psychological stress for the surgeon--did not form the greatest psychological stress; 2) the greatest psychological stress was elicited at the moment when the surgeon became faced with a setting in which his anatomical knowledge was lacking or a setting in which he presumed imminent bleeding; and 3) the excessively activated action potential of the brain possibly leads to a procedural error during surgery. A modified brain action potential measurement unit can reveal the latent psychological instability of surgeons that possibly leads to errors in surgical procedures.

Selection of behaviors and segmental coordination during larval locomotion is disrupted by nuclear polyglutamine inclusions in a new Drosophila Huntington's disease-like model.

Huntington's disease is an autosomal dominant neurodegenerative disorder that is caused by abnormal expansion of a polyglutamine tract in the huntingtin protein, resulting in intracellular aggregate formation and neurodegeneration. How neuronal cells are affected by such a polyglutamine tract expansion remains obscure. To dissect the ways in which polyglutamine expansion can cause neural dysfunction, the authors generated Drosophila transgenic strains expressing either a nuclear targeted or cytoplasmic form of pathogenic (NHtt-152Q(NLS), NHtt-152Q), or nonpathogenic (NHtt-18Q(NLS), NHtt-18Q) N-terminal human huntingtin. These proteins were expressed in the dendritic arborization neurons of the larval peripheral nervous system and their effects on neuronal survival, morphology, and larval locomotion were examined. The authors found that NHtt-152Q(NLS) larvae had altered dendrite morphology and larval locomotion, whereas NHtt-152Q, NHtt-18Q(NLS), and NHtt-18Q larvae did not. Furthermore, the authors examined the physiological defect underlying this disrupted larval locomotion in detail by recording spontaneous ongoing segmental nerve activity. NHtt-152Q(NLS) larvae displayed uncoordinated activity between anterior and posterior segments. Moreover, anterior segments had shorter bursts and longer interburst intervals in NHtt-152Q(NLS) larvae than in NHtt-18Q(NLS) larvae, whereas posterior segments had longer bursts and shorter interburst intervals. These results suggest that the pathogenic protein disrupts neuron function without inducing cell death, and describe how this dysfunction leads to a locomotor defect. These results also suggest that sensory inputs are necessary for the coordination of anterior and posterior body parts during locomotion. From these analyses the authors show that examination of motor behaviors in the Drosophila larvae is a powerful new model to dissect non-cell-lethal mechanisms of mutant Htt toxicity.