Protein deiminases: New players in the developmentally regulated loss of neural regenerative ability

• Published in: Developmental biology Vol. 355; no. 2; pp. 205 - 214
• Main Authors: Lange, Sigrun, Gögel, Stefanie, Leung, Kit-Yi, Vernay, Bertrand, Nicholas, Anthony P., Causey, Corey P., Thompson, Paul R., Greene, Nicholas D.E., Ferretti, Patrizia
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.07.2011
• Subjects: Age Factors; animal injuries; Animals; Apoptosis; Apoptosis - drug effects; Apoptosis - physiology; Arginine; Blotting, Western; Calcium; Calcium - metabolism; Cavitation; Chelating agents; Chick Embryo; chickens; chicks; citrulline; Deimination/citrullination; Development; Developmental stages; DNA Primers - genetics; embryo (animal); Enzymes; Gene expression; Gene Expression Regulation, Developmental - physiology; Humans; Hydrolases - antagonists & inhibitors; Hydrolases - metabolism; Immunohistochemistry; In Situ Nick-End Labeling; Mass Spectrometry; Oligonucleotide Array Sequence Analysis; Ornithine - analogs & derivatives; Ornithine - pharmacology; Peptidyl arginine deiminase; Post-translation; post-translational modification; Protein-arginine deiminase; Protein-Arginine Deiminases; proteins; Regeneration; RNA, Messenger - metabolism; Spinal cord; Spinal Cord Injuries - embryology; Spinal Cord Injuries - metabolism; Spinal Cord Injuries - physiopathology; Spinal cord injury; Spinal Cord Regeneration - physiology; Substantia alba; Development; Regeneration; Spinal cord; Peptidyl arginine deiminase; Deimination/citrullination; Apoptosis
• ISSN: 0012-1606; 1095-564X
• DOI: 10.1016/j.ydbio.2011.04.015

Spinal cord regenerative ability is lost with development, but the mechanisms underlying this loss are still poorly understood. In chick embryos, effective regeneration does not occur after E13, when spinal cord injury induces extensive apoptotic response and tissue damage. As initial experiments showed that treatment with a calcium chelator after spinal cord injury reduced apoptosis and cavitation, we hypothesized that developmentally regulated mediators of calcium-dependent processes in secondary injury response may contribute to loss of regenerative ability. To this purpose we screened for such changes in chick spinal cords at stages of development permissive (E11) and non-permissive (E15) for regeneration. Among the developmentally regulated calcium-dependent proteins identified was PAD3, a member of the peptidylarginine deiminase (PAD) enzyme family that converts protein arginine residues to citrulline, a process known as deimination or citrullination. This post-translational modification has not been previously associated with response to injury. Following injury, PAD3 up-regulation was greater in spinal cords injured at E15 than at E11. Consistent with these differences in gene expression, deimination was more extensive at the non-regenerating stage, E15, both in the gray and white matter. As deimination paralleled the extent of apoptosis, we investigated the effect of blocking PAD activity on cell death and deiminated-histone 3, one of the PAD targets we identified by mass-spectrometry analysis of spinal cord deiminated proteins. Treatment with the PAD inhibitor, Cl-amidine, reduced the abundance of deiminated-histone 3, consistent with inhibition of PAD activity, and significantly reduced apoptosis and tissue loss following injury at E15. Altogether, our findings identify PADs and deimination as developmentally regulated modulators of secondary injury response, and suggest that PADs might be valuable therapeutic targets for spinal cord injury. ► Spinal cord regenerative ability is lost with development. ► PAD3 (Ca++ dependent enzyme that deiminates proteins) is developmentally regulated. ► PAD3 increase following injury is greater in spinal cords that cannot regenerate. ► PAD inhibition reduces apoptosis and tissue damage in injured spinal cords. ► PAD/deimination are developmentally regulated modulators of secondary injury response.