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Updated: Aug 6, 2026
In Vivo Gene Transfer to Schwann Cells in the Rodent Sciatic Nerve by Electroporation
Published on: September 8, 2016
In vivo detection of Egr2 binding to target genes during peripheral nerve myelination
Sung-Wook Jang1, Scott E LeBlanc, Avtar Roopra
1Graduate Program in Cellular and Molecular Biology, University of Wisconsin, Madison, Wisconsin, USA.
Abstract:
Egr2/Krox20 is a zinc finger transactivator that regulates a diverse array of genes required for peripheral nerve myelination. Although several studies have elucidated the Egr2-regulated gene network, it is not clear if Egr2 regulates its target genes directly or indirectly through induction of other transactivators. Moreover, very few Egr2 binding sites have been identified in regulatory elements of myelin genes. To address this issue, we have successfully adapted chromatin immunoprecipitation assays to test if Egr2 binds directly to target genes in myelinating rat sciatic nerve. These experiments demonstrate direct binding of Egr2 to previously described binding sites within the Schwann cell enhancer of the myelin basic protein gene. Furthermore, we show Egr2 binding to a conserved site within the myelin-associated glycoprotein gene. Finally, our experiments provide the first evidence that Egr2 directly regulates expression of desert hedgehog, which is critically involved in development, maintenance and regeneration of multiple nerve elements including myelinated fibers. Surprisingly, this analysis has identified an apparent preponderance of Egr2 binding sites within conserved intron sequences of several myelin genes. Application of chromatin immunoprecipitation analysis to myelination in vivo will prove to be a valuable asset in assaying transcription factor binding and chromatin modifications during activation of myelin genes.
Insights
The transcription factor Egr2 (early growth response 2) directly binds to key genes involved in peripheral nerve myelination, including myelin basic protein and myelin-associated glycoprotein. This study reveals novel direct Egr2 regulation of desert hedgehog, crucial for nerve development and repair.
Area of Science:
- Neuroscience
- Molecular Biology
- Genetics
Background:
- Egr2/Krox20 is a critical transcription factor for peripheral nerve myelination.
- The precise mechanisms of Egr2's regulation of myelin genes, whether direct or indirect, remain incompletely understood.
- Few Egr2 binding sites have been identified in the regulatory regions of myelin genes.
Purpose of the Study:
- To investigate whether Egr2 directly binds to target genes involved in peripheral nerve myelination.
- To identify novel direct targets of Egr2 regulation in the context of myelination.
- To adapt and apply chromatin immunoprecipitation (ChIP) assays for in vivo analysis of transcription factor binding during myelination.
Main Methods:
- Chromatin immunoprecipitation (ChIP) assays were adapted and performed on myelinating rat sciatic nerve tissue.
- ChIP assays were used to detect direct binding of Egr2 to regulatory elements of myelin genes.
- Analysis focused on myelin basic protein (MBP), myelin-associated glycoprotein (MAG), and desert hedgehog (Dhh) genes.
Main Results:
- Direct binding of Egr2 to the Schwann cell enhancer of the myelin basic protein gene was confirmed.
- Egr2 binding was demonstrated at a conserved site within the myelin-associated glycoprotein gene.
- The study provides the first evidence of direct Egr2 regulation of desert hedgehog expression.
- A significant number of Egr2 binding sites were unexpectedly found within conserved intronic sequences of several myelin genes.
Conclusions:
- Egr2 directly regulates key genes essential for peripheral nerve myelination, including MBP, MAG, and Dhh.
- The findings reveal novel direct transcriptional targets of Egr2 and expand the understanding of its regulatory network.
- Chromatin immunoprecipitation assays in vivo are a powerful tool for studying transcription factor binding and chromatin modifications during the activation of myelin genes.
