Doublecortin-Like Kinases Promote Neuronal Survival and Induce Growth Cone Reformation via Distinct Mechanisms
NEURON
Authors: Nawabi, Homaira; Belin, Stephane; Cartoni, Romain; Williams, Philip R.; Wang, Chen; Latremoliere, Alban; Wang, Xuhua; Zhu, Junjie; Taub, Daniel G.; Fu, Xiaoqin; Yu, Bin; Gu, Xiaosong; Woolf, Clifford J.; Liu, Judy S.; Gabel, Christopher V.; Steen, Judith A.; He, Zhigang
Abstract
After axotomy, neuronal survival and growth cone reformation are required for axon regeneration. We discovered that doublecortin-like kinases (DCLKs), members of the doublecortin (DCX) family expressed in adult retinal ganglion cells (RGCs), play critical roles in both processes, through distinct mechanisms. Overexpression of DCLK2 accelerated growth cone re-formation in vitro and enhanced the initiation and elongation of axon re-growth after optic nerve injury. These effects depended on both the microtubule (MT)-binding domain and the serine-proline-rich (S/P-rich) region of DCXs in-cis in the same molecules. While the MT-binding domain is known to stabilize MT structures, we show that the S/P-rich region prevents F-actin destabilization in injured axon stumps. Additionally, while DCXs synergize with mTOR to stimulate axon regeneration, alone they can promote neuronal survival possibly by regulating the retrograde propagation of injury signals. Multifunctional DCXs thus represent potential targets for promoting both survival and regeneration of injured neurons.
Epilepsy associated with autism and attention deficit hyperactivity disorder: Is there a genetic link?
BRAIN & DEVELOPMENT
Authors: Lo-Castro, Adriana; Curatolo, Paolo
Abstract
Autism Spectrum Disorders (ASDs) and Attention Deficit and Hyperactivity Disorder (ADHD) are the most common comorbid conditions associated with childhood epilepsy. The co-occurrence of an epilepsy/autism phenotype or an epilepsy/ADHD phenotype has a complex and heterogeneous pathogenesis, resulting from several altered neurobiological mechanisms involved in early brain development, and influencing synaptic plasticity, neurotransmission and functional connectivity. Rare clinically relevant chromosomal aberrations, in addition to environmental factors, may confer an increased risk for ASDs/ADHD comorbid with epilepsy. The majority of the candidate genes are involved in synaptic formation/remodeling/maintenance (NRX1, CNTN4, DCLK2, CNT-NAP2, TRIM32, ASTN2, CTNTN5, SYN1), neurotransmission (SYNGAP1, GABRG1, CHRNA7), or DNA methylation/chromatin remodeling (MBD5). Two genetic disorders, such as Tuberous sclerosis and Fragile X syndrome may serve as models for understanding the common pathogenic pathways leading to ASDs and ADHD comorbidities in children with epilepsy, offering the potential for new biologically focused treatment options. (C) 2013 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.