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Expression data from aquatic axolotl full thickness epithelial flank wounds, innervated limbs, and denervated limbs collected over seven days

ABSTRACT: Salamander limb regeneration is dependent upon tissue interactions that are local to the amputation site. Communication among limb epidermis, peripheral nerves, and mesenchyme coordinate cell migration, cell proliferation, and tissue patterning to generate a blastema, a mass of progenitor cells that forms missing limb structures. An outstanding question is how molecular cross-talk between these tissues gives rise to the regeneration blastema. To identify genes associated with epidermis-nerve-mesenchymal interactions during limb regeneration, we examined histological and transcriptional changes during the first week following injury in the wound epidermis and subjacent cells between three injury types; 1) a flank wound on the side of the animal that will not regenerate a limb, 2) a denervated limb that will not regenerate a limb, and 3) an innervated limb that will regenerate a limb. Early, histological and transcriptional changes were highly similar between the three injury types, presumably because a common wound-healing program is employed across anatomical locations. However, we identified transcripts that were enriched in the limb compared to the flank and are associated with vertebrate limb development. Many of these genes were activated before blastema outgrowth and in situ hybridization showed that some of these genes were expressed in specific tissue types including the epidermis, peripheral nerve, and mesenchyme. We also identified a relatively small group of transcripts that were more highly expressed in innervated limbs versus denervated limbs. These transcripts encode for proteins that are associated with myelination of peripheral nerves, epidermal maintenance, and cell proliferation, suggesting that denervation affects myelinating Schwann cells, epidermal cell function, and proliferation of mesenchymal cells. Overall, our study identifies limb-specific and nerve-dependent genes that are upstream of regenerative growth, and thus promising candidates for the regulation of blastema formation.

ORGANISM(S): Ambystoma mexicanum

PROVIDER: GSE37198 | GEO | 2012/09/17

SECONDARY ACCESSION(S): PRJNA158557

REPOSITORIES: GEO

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Project description:Salamander limb regeneration is dependent upon tissue interactions that are local to the amputation site. Communication among limb epidermis, peripheral nerves, and mesenchyme coordinate cell migration, cell proliferation, and tissue patterning to generate a blastema, a mass of progenitor cells that forms missing limb structures. An outstanding question is how molecular cross-talk between these tissues gives rise to the regeneration blastema. To identify genes associated with epidermis-nerve-mesenchymal interactions during limb regeneration, we examined histological and transcriptional changes during the first week following injury in the wound epidermis and subjacent cells between three injury types; 1) a flank wound on the side of the animal that will not regenerate a limb, 2) a denervated limb that will not regenerate a limb, and 3) an innervated limb that will regenerate a limb. Early, histological and transcriptional changes were highly similar between the three injury types, presumably because a common wound-healing program is employed across anatomical locations. However, we identified transcripts that were enriched in the limb compared to the flank and are associated with vertebrate limb development. Many of these genes were activated before blastema outgrowth and in situ hybridization showed that some of these genes were expressed in specific tissue types including the epidermis, peripheral nerve, and mesenchyme. We also identified a relatively small group of transcripts that were more highly expressed in innervated limbs versus denervated limbs. These transcripts encode for proteins that are associated with myelination of peripheral nerves, epidermal maintenance, and cell proliferation, suggesting that denervation affects myelinating Schwann cells, epidermal cell function, and proliferation of mesenchymal cells. Overall, our study identifies limb-specific and nerve-dependent genes that are upstream of regenerative growth, and thus promising candidates for the regulation of blastema formation. We used microarray analysis to determine the gene expression changes that take place during limb regeneration, flank wound healing, and an denervated amputated limb. Epidermal tissue and cells adhered to the epidermis were collected as samples. Two harvested samples was pooled for each animal. Four biological replicates were collected from uninjured epidermis (D0) and at 1, 3, and 7 days post injury.

Project description:This study aimed to quantify the regulation of transcripts in the hairy skin of the back of adult rats in the condition of loss of sensory and autonomic (sympathetic) innervation (i.e., denervated). Denervated skin has reduced wound healing capacity, reduced proliferation of epidermal progenitor cells, and also expresses factors that regulate ingrowth of sensory and sympathetic axons from neighboring regions of innervated skin. It was expected that this quantification f transcript regulation would offer insight into the general and specific mechanisms that may contribute to these important biological processes. All animals were adult (200-250g) Sprague-Dawley female rats. Three conditions were examined. Groups were naive (n=6), 7-day denervated skin (n=5), and 14-day (n=5) denervated skin. Denervation preparations: Full-thickness incision along long-axis of the body 1cm to right of midline (to avoid injuring skin to be sampled). Incision was centered rostro-caudally on the T13 (thoracic 13) costo-vertebral angle so as to allow access to the T9-L2 (lumbar 2) cutaneous nerves. Skin was reflected to the left and the left T9, T10, L1, and L2 dorsal and lateral cutaneous nerves were isolated, ligated with 7-0 monofilament suture close to their exit from the body wall, and transected. Approximately 5mm of the distal portion of the nerve was resected. The T11 nerves were left unperturbed and were not isolated from the surrounding fascia. This generated two strips of skin that were devoid of sensory and autonomic innervation (those strips served by the T9 and T10 nerves, and by the L1 and L2 nerves). Between these denervated strips of skin was a strip of skin that retained the sensory and autonomic axons supplied by T11 nerves. The denervated zones were identified by mapping the cutaneous trunk muscle (CTM) reflex (see Petruska-JC et al. (2013) Journal of Comparative Neurology; Diamond-J et al., (1992) J Neuroscience), and the border marked with pen and remarked every few days. The samples were taken from the rostral (T9/10) denervated zone. Samples from naive animals (no denervation) were taken from the same region, using the dorsal cutaneous nerves as registration landmarks. Animals displayed no signs of overgrooming of the denervated skin. Because the CTM inserts onto the dermis of this region of skin, samples necessarily include both skin and underlying CTM (which is innervated from another source so was not denervated in the experiment).

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Expression data from aquatic axolotl full thickness epithelial flank wounds, innervated limbs, and denervated limbs collected over seven days

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