Elsevier

Neuroscience

Volume 152, Issue 3, 27 March 2008, Pages 601-608
Neuroscience

Cellular neuroscience
Expression of interleukin-6 receptor α in normal and injured rat sciatic nerve

https://doi.org/10.1016/j.neuroscience.2008.01.014Get rights and content

Abstract

Interleukin-6 (IL-6) is a pleiotropic cytokine synthesized by many different cells after appropriate stimulation. IL-6 binds first to the interleukin-6 receptor alpha (IL6-Rα) and then this complex binds to the signal-transducing gp130 receptor, forming a functional hexameric receptor complex. We observed by Western blot analysis with anti-IL6-Rα two bands of ∼80 kDa and ∼110 kDa in the rat sciatic nerve, cerebral cortex, spleen, pancreas and liver, corresponding to the mature glycosylated form and possibly to the dimer of the non-glycosylated precursor protein. By immunohistochemistry, high levels of IL6-Rα expression are observed in non-myelinating Schwann cells. In myelinating Schwann cells IL6-Rα is present as discrete dots in the perinuclear region, in distinct membrane domains of the Schwann cell sheath and at the nodes of Ranvier, suggesting that IL6-Rα is clustered both on the axonal side of the node and within the Schwann cells. After sciatic nerve crush injury IL6-Rα is upregulated in denervated Schwann cells between the myelin ovoids during the period of Schwann cell proliferation. The expression of IL6-Rα continues during the period of remyelination, suggesting that IL6-Rα might be involved in both Schwann cell proliferation and remyelination of the rat sciatic nerve.

Section snippets

Teased nerve preparations

All procedures involving animals were carried out in accordance with the Institutional Guide for Ethical Animal Experimentation (National Autonomous University of Mexico), minimizing the number of animals used and their suffering. Male Wistar rats (250–350 g) were used in all experiments. Rats were killed by ether or CO2 overexposure. Crushed sciatic nerves, sympathetic trunk and sciatic nerve from normal adult rats were excised and desheathed. The nerves were split into manageable strands and

Immunoblot analysis of IL6-Rα in different tissues

Western blotting with anti-IL6-Rα of whole sciatic nerve, cerebral cortex, spleen, pancreas and liver revealed two bands of ∼80 kDa and ∼110 kDa (Fig. 1). The ∼80 kDa band corresponds to the glycosylated monomer of the mature form of IL6-Rα, while the ∼110-kDa band might correspond to a non-glycosylated dimer of IL6-Rα. All of the tissues we studied expressed IL6-Rα, but differences in the levels of expression were observed (Fig. 1).

Immunolocalization of IL6-Rα in the sciatic nerve

IL6-Rα expression was examined by immunohistochemistry in

Discussion

The cDNA of the human IL6-Rα encodes a protein of 468 amino acids. The mature form of IL6-Rα is a glycosylated 80 kDa form of the predicted 50 kDa precursor protein (Hirata et al 1989, Varghese et al 2002). By Western blot analysis the rabbit antiserum against the IL6-Rα recognizes two bands, one of ∼80 kDa corresponding to the mature glycosylated molecule and another one of ∼110 kDa, which might represent a dimer of the non-glycosylated precursor protein of 50 kDa. Both bands were observed in

Acknowledgments

We thank Prof. R. Mirsky and Dr. Bob Amess for critically reading and correcting the manuscript, Biol. Juan Carlos Rivera-Mulia for assistance with the figures and the deconvolution system, MVZ Claudia Rivera-Cerecedo for providing us with the rats used in this work. This work was supported by Conacyt-México, grant 33540-N and UAEMex grant 1977/2004 to M. A. R. Dent.

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    Present address: Department of Zoology, University of Oxford, The Tinbergen Building, South Parks Road, Oxford OX1 3PS, UK.

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