Neurotrophin mediated regeneration of sensory afferents after dorsal root rhizotomy

Transcription

1 Neurotrophin mediated regeneration of sensory afferents after dorsal root rhizotomy ASIA 2016 George M. Smith Shriners Hospitals Pediatric Research Center Department of Neuroscience Temple University, Philadelphia

2 NEURITE TARGETING Robin Cooper, PhD

3 Neurotrophic Factors: A family of proteins that are responsible for the growth and survival of developing neurons and the maintenance of mature neurons. Some have the ability to direct or guide axons both in the developing and adult nervous system. Neuronal effects dependent on receptor(s) expressed by individual neurons. Can be used to increase axon growth or sprouting after injury to either the central or peripheral nervous systems.

4 Neurotrophic Factors family members: Neurotrophins GDNF family NGF TrkA GDNF GFR-α1 NT-3 BDNF TrkC TrkB Neurturin Artemin GFR-α2 GFR-α3 cret NT-4/5 Persephin GFR-α4 Ibanez, 1998 Trends in Neuroscience, 21:

5 Recombinant Lentivirus

6 Brachial plexus injuries and Erb s palsy

7 Model for sensory afferent sprouting in the noninjured spinal cord L5 L4

8 Dorsal root entry zone model Rhizotomy

9 Exogenous expression of Artemin, NGF, and GFP Artemin NGF Lenti-Artemin (4X) Lenti-NGF (4X) 10X 10X

10 NGF and Artemin promote regeneration of peptidergic nociceptive axons into the spinal cord

11 Neurotrophic factor influences topographic distribution of CGRP + axons

12 Artemin and GDNF promote regeneration of non-peptidergic axons into the spinal cord

13 GDNF promote regeneration of myelinated axons

14 NGF- or Artemin-induced regeneration results in functional return of nociception

15 Proprioceptive sensory afferents 1. Largest and fastest conducing sensory axons, originating from muscle spindles and golgi tendon organs. 2. Involved in signaling both conscience and non-conscience information on muscle contraction, stretch, and joint angles. 3. Appear to be the least capable of regenerating through the dorsal root entry zone and into the spinal cord. 4. Express Trk-C receptor and neurotrophin-3 mediates their growth during development and only partially during regeneration in adults.

16 Increasing intrinsic axon growth by constitutively active Rheb to activate mtor pathway in adult neurons 1. Upstream positive regulator of mtor 2. PTEN -/- increase mtor and axon regeneration. 3. mtor is a major growth pathway activating translation and reducing autophagy The Scientist :59 4. Inhibition of mtor by Rapamycin reduces systemic growth.

17 ps6 expression peaks at P2 DRG and cortical neurons but diminished in adult DRG and cortical neurons. NF ps6

18 Expression of Rheb increases axon outgrowth from adult DRG neurons carheb/aav

19 Rheb expression by adeno-associated virus vector in vivo. GFP/AAV GFP/AAV carheb/aav

20 Rheb alone does not promote the growth of regenerating sensory axons into the spinal cord.

21 Rheb expression in the DRG enhances the regenerative response of NT3 on deeper myelinated sensory afferents and supports better foot placement.

22 Neuron July 10; 79(1):

23 SAD kinases are downregulated after birth in DRG neurons

24 AAV-BRSK2 expression

25 AAV-BRSK/AAV-GFP in DRG and LV-NT3 in spinal cord DREZ GFP CGRP AAV-GFP control GFP Laminin DREZ

26 DRG neuronal expression of BRSK2 enhances NT3 mediated regeneration AAV-BRSK/AAV-GFP in DRG AAV-BRSK/AAV-GFP in DRG and LV-NT3 Normal

27 Graduate Students Kathy Keefe Imran Sheikh Kristine Ziemba Paula Heron Chris Trimby Chen Zhang Postdoctoral Fellows Mario Romero, Ph.D. Nagarathnamma Rangappa, Ph.D. Xiao-Qing Tang, M.D. Ph.D. Nitin Chouthai, M.D. Jie Cai, Ph.D. Xin-Hua Hu, Ph.D. Ying Jin, Ph.D. Gabrielle Curinga, Ph.D. Biswarup Ghosh, Ph.D. Lakshmi Kelamangalath, Ph.D. Smith Lab. Collaborators Xiao-Ming Xu, M.D., Ph.D., IUPUI Alexander Rabchesky, Ph.D., UK Mark Hamann M.D., UK Chih-Lung Lin M.D., Chang Gung University, Taiwan Young-Jin Son, Ph.D., Temple Andrew Spence Ph.D., Temple Barbara Krynska Ph.D. Temple Itzhak Fischer Ph.D. Dexel Funding Agencies: NIH/National Institute of Neurological Disorders and Stroke Department of Defense Shriners Hospital Pediatric Research Foundation

28 Factors governing axonal growth Growth mechanisms independent of neural activity are governed by either the intrinsic state of the neuron or the extracellular environment. Intrinsic Factors: change with neuronal age. Cyclic nucleotide levels (camp or cgmp) Receptor expression or density for either inhibitory molecules or growth promotive molecules. Reduced signaling through growth pathways (e.g., mtor, braf). Extrinsic Factors: differential expression during development, maturation or injury states. Increase in inhibitory extracellular matrix or myelin proteins. Increase chemorepulsive factors (eg: semaphorins, EPH/ephrins, netrins) Decrease chemoattractive factors (eg: neurotrophins, netrins).

29 DREZ Regeneration Project Romero M.I. and G.M. Smith (1998) Adenoviral gene transfer into the normal and injured spinal cord: enhanced transgene stability by combined administration of temperature-sensitive virus and transient immune blockade. Gene Therapy 5: Romero M.I., N. Rangappa, L. Li, E. Lightfoot, M.G. Garry, G.M. Smith. (2000) Extensive sprouting of sensory afferents and hyperalgesia induced by conditional expression of NGF in the adult spinal cord. J. Neurosci. 20: Mario Romero, Ph.D. Romero M.I., N. Rangappa, M.G. Garry, G.M. Smith. (2001) Functional regeneration of chronically-injured sensory afferents into adult spinal cord following neurotrophin gene therapy. J. Neurosci. 21: Tang X.Q., D.L. Tanelian, and G.M. Smith. (2004) Semaphorin3A inhibits nerve growth factor-induced sprouting of nociceptive afferents in adult rat spinal cord. J. Neurosci. 24: Nagarathnamma Rangappa, Ph.D. Tang X.Q., J. Cai, K.D. Nelson, X.J. Peng, and G.M. Smith (2004) Functional repair of dorsal root injury by guidance conduits and neurotrophin. Eur. J. Neurosci. 20: Chaudhry N, de Silva U, Smith GM. (2006) Cell adhesion molecule L1 modulates nerve-growth-factor-induced CGRP-IR fiber sprouting. Exp Neurol. 202: Xiao-Qing Tang, Ph.D Tang XQ, Heron P, Mashburn C, Smith GM (2007) Targeting sensory axon regeneration in adult spinal cord. J. Neurosci. 27:

30 cfos distribution within the spinal cord after NGF or Artemin induced axonal regeneration cfos-conrol cfos-ngf cfos-artemin

31 Summary: NGF and artemin promote regeneration of peptidergic nociceptive axons, but not large diameter myelinated axons. Both NGF and artimen induce functional return of thermal nociception but not tactile or proprioceptive responses. Disruption of neurotrophin signaling induces aberrant connectivity leading to mistargeting of sensory afferents within the cord and mild hyperalgesia. Are additional factors required to induce regeneration of large diameter sensory afferents (tactile and proprioceptive)?

32 Axon guidance during development Barallobre, MJ et al., 2005, Brain Res Rev. 49 (1):22-47