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.
*Z. WANG, I. VENKATESH, N. KRUEGER, D. NOWAK, B. CALLIF, B. MAUNZE, M. G. BLACKMORE;
Dept. of Biomed. Sci., Marquette Univ., Milwaukee, WI
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