By using novel, systemically deliverable, small inhibitory peptides developed in the PI's lab, we aim to determine whether targeting both extracellular inhibitory and neuron-intrinsic factors can markedly improve axon regeneration and functional recovery after spinal cord injury (SCI). Severed CNS axons fail to regenerate due to the extrinsic inhibitory environment and the reduced intrinsic growth capacity of mature neurons. Chondroitin sulfate proteoglycans (CSPGs) generated by glial scars strongly suppress axon extension into and beyond the lesion area and are the major molecular targets for treating SCI. Recently, we and other labs identified the LAR and PTP phosphatases as receptors that mediate CSPG inhibition. Deleting either of them stimulated axon growth after SCI. Recent studies using conditional knockout mice suggested that PTEN critically restricts the intrinsic regenerative capacity of injured CNS axons. Thus, suppressing CSPG receptors and PTEN is promising for promoting axon regeneration after CNS injury. We have designed small peptides to block functions of these inhibitory molecules by targeting their specific domains and demonstrated the high efficacy of our peptides for promoting axon growth in vitro and in vivo. Since CSPGs and PTEN appear to limit growth by different signaling pathways, inhibition of both may act synergistically to promote axon regeneration by reducing environmental inhibitory influence at the lesion site and enhancing intrinsic growth capacity of mature neurons. We hypothesize that CSPGs and PTEN are critical contributors to regenerative failure of CNS neurons and that combined inhibition of both promotes axon regeneration better than inhibition of either one alone. We propose to address the following 3 Specific Aims: 1) determine whether transgenic deletion or peptide blockade of two CSPG receptors yields better axon growth in vitro and in vivo and functional recovery in adult mice with SCI than suppressing either receptor alone; 2) determine whether PTEN blockade with peptides stimulates similar degrees of axon growth and functional recovery as transgenic PTEN deletion in vitro and in vivo; 3) determine whether blocking both CSPG signaling and PTEN with peptides promotes greater axon regeneration and behavioral recovery after SCI than blocking either one alone. The results of peptide treatments will be compared with those of transgenic mouse experiments. Our novel strategy to administer small compounds systemically alone or in combination may facilitate development of a practical therapy for CNS injury.
By comparison to axonal growth and functional recovery in knockout mice we will study the efficacy of our novel peptides on suppressing function of CSPG receptors and PTEN. By simultaneously targeting the CNS environmental inhibitory and neuron-intrinsic factors, we aim to promote better axon regeneration and functional recovery in adult rodents with SCI than by targeting either one alone. The invention and use of systemically deliverable blocking peptides may advance our ability to treat CNS axon injuries by promoting functional regeneration.
|Ohtake, Yosuke; Saito, Atsushi; Li, Shuxin (2018) Diverse functions of protein tyrosine phosphatase ? in the nervous and immune systems. Exp Neurol 302:196-204|
|Wang, Xue-Wei; Li, Qiao; Liu, Chang-Mei et al. (2018) Lin28 Signaling Supports Mammalian PNS and CNS Axon Regeneration. Cell Rep 24:2540-2552.e6|
|Sainath, Rajiv; Armijo-Weingart, Lorena; Ketscheck, Andrea et al. (2017) Chondroitin sulfate proteoglycans negatively regulate the positioning of mitochondria and endoplasmic reticulum to distal axons. Dev Neurobiol 77:1351-1370|
|Nathan, Fatima M; Li, Shuxin (2017) Environmental cues determine the fate of astrocytes after spinal cord injury. Neural Regen Res 12:1964-1970|
|Ohtake, Yosuke; Kong, Weimin; Hussain, Rashad et al. (2017) Protein tyrosine phosphatase ? regulates autoimmune encephalomyelitis development. Brain Behav Immun 65:111-124|
|Ohtake, Yosuke; Wong, Daniella; Abdul-Muneer, P M et al. (2016) Two PTP receptors mediate CSPG inhibition by convergent and divergent signaling pathways in neurons. Sci Rep 6:37152|
|Feng, Dechun; Dai, Shen; Liu, Fengming et al. (2016) Cre-inducible human CD59 mediates rapid cell ablation after intermedilysin administration. J Clin Invest 126:2321-33|
|Ohtake, Yosuke; Smith, George M; Li, Shuxin (2016) Reactive astrocyte scar and axon regeneration: suppressor or facilitator? Neural Regen Res 11:1050-1|
|Ohtake, Yosuke; Li, Shuxin (2015) Molecular mechanisms of scar-sourced axon growth inhibitors. Brain Res 1619:22-35|
|Xu, Bin; Park, Dongsun; Ohtake, Yosuke et al. (2015) Role of CSPG receptor LAR phosphatase in restricting axon regeneration after CNS injury. Neurobiol Dis 73:36-48|
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