Analysis of genes induced in peripheral nerve after axotomy using cDNA microarrays

Abstract

One of the most striking features of neurons in the mature peripheral nervous system is their ability to survive and to regenerate their axons following axonal injury. To perform a comprehensive survey of the molecular mechanisms that underlie peripheral nerve regeneration, we analyzed a cDNA library derived from the distal stumps of post-injured sciatic nerve which was enriched in non-myelinating Schwann cells using cDNA microarrays. The number of up-and down-regulated genes in the transected sciatic nerve was 370 and 157, respectively, of the 9596 spotted genes. In the up-regulated group, the number of known genes was 216 and the number of expressed sequence tag (EST) sequences was 154. In the down-regulated group, the number of known genes was 103 and that of EST sequences was 54. We obtained several genes that were previously reported to be involved in regeneration of the injured neurons, such as cathepsin D, ninjurin 1, tenascin C, and co-receptor for glial cell line-derived neurotrophic factor family of trophic factors. In addition to unknown genes, there seemed to be a lot of annotated genes whose role in nerve regeneration remains unknown. Keywords: cDNA microarrays, injury-induced molecules, nerve regeneration, Schwann cell, sciatic nerve. One of the most striking features of neurons in the mature PNS is their ability to survive and to regenerate their axons following axonal injury. It has been increasingly evident that the success of axonal regeneration is dependent on the intrinsic as well as extrinsic growth properties of the axotomized neuron. The environment in which PNS axons regenerate consists of Schwann cells and their basal laminae, fibroblasts, collagen, degenerating myelin and phagocytic cells (Fawcett and Keynes 1990;Bunge and Griffin 1992;Araki and Milbrandt 1996). After nerve injury, the distal axonal and myelin segment undergoes dissolution and absorption by the surrounding cellular environment, a process called Wallerian degeneration. Then, the remaining Schwann cells divide and align longitudinally within basal lamina tubes. Growth cones from regenerating axons extend along the Schwann cell bands (the band of Bü ngner), growing along the Schwann cell membranes and basal laminae (Keynes 1987;Reichert et al. 1994;Grill and Tuszynske 1999). Such biological and morphological changes of Schwann cells are thought to be controlled by injury-induced molecules that are expressed by neurons and Schwann cells themselves. Especially, at around 7 days after nerve injury, many nerve regeneration-related factors, such as p75 NTR , co-receptor for glial cell line-derived neurotrophic factor family of trophic factors (GFRa1) and ninjurin 1 and 2, reach peak levels (Taniuchi et al. 1988;Araki and Milbrandt 1996;Baloh et al. 1997;Araki and Milbrandt 2000), and the growth cones of regenerating axons begin to move over the Schwann cell surface (Taniuchi et al. 1988;Goodrum et al. 1994). Successive large-scale screening, however, is required to reveal the spectrum of genes involved in this regenerat...

The Calcium-binding Proteins S100A8 and S100A9 Initiate the Early Inflammatory Program in Injured Peripheral Nerves

“…4F). Overall, these findings support and extend the observations made by others, which focused mainly on either the individual P or D changes or on later time points post-axotomy (25)(26)(27)(28)(29)(30)(31)(32)(33).…”

“…Here we first confirmed and expanded the transcriptional profiling studies in peripheral nerves (25)(26)(27)(28)(29)(30)(31)(32)(33). Using comparative genome-wide transcriptional profiling and subsequent bioinformatics (Ingenuity, NextBio) analyses in the P and D stumps on day 1 post-axotomy, we recorded early gene expression changes in the severed sciatic nerve in rats.…”

DNA polymorphisms as tools for spinal cord injury research

“…The genes selected for this frequency analysis were: APOE (involved with cholesterol metabolism, which is essential for myelin membrane growth 17 ), ALOX12 (involved in the modulation of inflammatory response, 18 neurite regeneration 19 and nerve cell death by oxidative stress under glutamate depletion 20 ), BDNF (a neurotrophic factor that promotes the development, regeneration, survival and maintenance of function of neurons, 21 overexpressed in fibroblasts used to promote regeneration of SCI 22,23 ) and NINJ1 (a membrane protein that is upregulated after nerve injury 24 ).…”

Complementariness and Functional Parcellation of Neurotrophin Actions on the Oculomotor System

“…Extraocular motoneurons did not express CGRP in basal conditions but they did so at short times after axotomy (1-3 days, Figure 3A). This early induction is indicative of a motoneuronal switch to a regenerative state in which new molecules involved in neuronal survival and axonal regeneration can be produced [93][94][95][96][97]. Thirty days after lesion, a new peak in CGRP expression was observed ( Figure 3A), which might coincide with the reinnervation of new target tissue, as it has been described for hypoglossal motoneurons [98], or alternatively could be related to an increased availability of trophic support from other sources.…”