Overexpression of KLF6 in corticospinal tract neurons promotes axon growth after spinal injury

Zimei Wang PhD MD Marquette University

Axonal regeneration in the central nervous system is limited in part by a developmental decline in the intrinsic regenerative capacity of central nervous system (CNS) neurons. Changes in gene expression are likely involved, and thus transcription factors that orchestrate gene expression are attractive targets to understand and overcome intrinsic limits to axon growth in adult neurons. We have shown previously that forced expression of pro-regenerative transcription factors, including Sox11 and a transcriptionally activated form of Krüppel-like factor 7 (VP16-KLF7), can enhance the regenerative ability of injured corticospinal tract (CST) neurons. Here we assessed the ability of KLF6, a transcription factor closely related to KLF7, to promote CST regeneration. KLF6 was delivered to cortical neurons by injection of AAV-KLF6 along with AAV-EGFP tracer, and animals were subjected to pyramidotomy or unilateral cervical hemisection. KLF6 expression promoted a robust increase in midline crossing by transduced (EGFP+) CST axons in the pyramidotomy model, and extensive CST growth in the spinal injury model that extended up to 3mm from the injury site. Immunohistochemistry confirmed viral-mediated upregulation of KLF6 protein, but also revealed endogenous expression of KLF6 in cortical neurons that appeared largely unaffected by spinal axotomy. Intriguingly, forced expression of KLF6 had more modest effects in sensory neurons confronted with spinal injury, causing a decrease in net retraction but not sprouting or regeneration beyond the injury site. To identify potential functional interactions with other pro-regenerative transcription factors, either Sox11 or Myc were co-expressed with KLF6 in cortical neurons challenged with spinal injury. Neither combinatorial treatment resulted in significant increases in CST axon growth above the level of KLF6 alone. Ongoing experiments are testing co-expression of KLF6 with additional pro-regenerative factors including Jun and DCLK. In addition, using CRISPR-mediated knockdown in a Cas9-expressing transgenic mouse, we are currently testing combined KLF6 overexpression and knockdown of PTEN. Finally, RNAseq experiments are underway to identify KLF6 target genes. Overall, these data identify KLF6 as a potent transcriptional promoter of axon regeneration in the injured CST.

Abstract Authors
*Z. WANG, I. VENKATESH, N. KRUEGER, D. NOWAK, B. CALLIF, B. MAUNZE, M. G. BLACKMORE;
Dept. of Biomed. Sci., Marquette Univ., Milwaukee, WI
Disclosures
Z. Wang: None. I. Venkatesh: None. N. Krueger: None. D. Nowak: None. B. Callif: None. B. Maunze: None. M.G. Blackmore: None.

LINK: Session 323 – Spinal Cord Injury Models and Mechanisms

NIH RePorter Link: The Report Expenditures and Results tool allows users to search a repository of NIH-funded research projects and access publications and patents resulting from NIH funding
Project Number: 5R01NS083983-05 Former Number: 5R01NS083983-04
Contact PI / Project Leader: BLACKMORE, MURRAY G
Title: FUNCTIONAL TESTING OF KLF7 IN SPINAL CORD INJURY: AN OPTOGENETIC APPROACH
Awardee Organization: MARQUETTE UNIVERSITY

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2 Responses to Overexpression of KLF6 in corticospinal tract neurons promotes axon growth after spinal injury

  1. Michael says:

    Well that’s a very fascinating outcome for all of the wonderful people in this research field and it is also great news for the SCI people that are hoping for research to help them with their everyday activities and even a cure for paralysis which would change their lives forever. I’m always curious about research and all of the wonderful cutting edge things happening every day that will hopefully come together full circle and find one major piece of the puzzle that could end and cure all of the terrible diseases known to humankind and nobody would ever have to watch a loved one struggle to live every day or watch them go through so much pain as their health declines until the day comes for the pain to be gone. Keep up the great research and hard work that all of you do to help make people’s dreams become a reality and God Bless Each And Every One Of You Always And Forever.

    • Michelle says:

      This is amazing, I myself is paralyzed from the waist down. T11 to be exact!! i’am always reading up on cures & always staying hopeful that someday i will walk again. Keep up the good work we are thankful for the hard work your doing to help us walk again💟

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