Expression of regeneration-associated cytoskeletal proteins reveals differences and similarities between regenerating organs

Abstract

The unique events which allow regeneration of an entire organ to occur are formation of a specialized wound epidermis and accumulation of progenitor cells (blastemal cells) at the amputated surface to form a blastema. In order to identify some of the molecular events underlying the early stages of the regenerative process which are either common to different systems or specific to one of them, we have investigated whether molecules which are induced in limb blastemas are also expressed in skin repair and during regeneration of other complex body structures (lower jaws, upper jaws, and tails). In addition, we have addressed the issue of the identity of progenitor cells during jaw development and regeneration by analyzing the expression of limb blastemal markers in the developing head and face. We have focused on cytoskeletal components, and particularly on the epidermal keratin NvKII, the simple epithelial keratins 8 and 18 and 22/18, because they are among the few molecules which have been shown to be associated with regeneration in the limb and may play significant roles in various developmental processes. Some important findings emerge from this study: 1) Expression of the epidermal keratin NvKII, unlike that of its mammalian homologue K6, is not simply induced in response to wounding, but is associated with regeneration of specific organs. In fact, NvKII is expressed in regenerating limbs and tails, but not in upper or in lower jaw regenerates, demonstrating the existence of molecular differences in the composition of the wound epidermis in these systems. This, together with the fact that NvKII mRNA is regulated by retinoic acid, which differentially affects patterning of limbs and jaws, argues for distinct inductive abilities of the wound epidermis in different organs. 2) In contrast to the differential expression of the epidermal keratin NvKII, the regeneration‐associated cytoskeletal molecules identified in limb blastemal cells are expressed in a similar fashion in jaw and tail blastemas. Therefore, it appears that similar cellular events lead to the establishment of an actively proliferating population of progenitor cells from the stump of different organs. Finally, the mesenchyme of the facial rudiments, unlike that of developing limb buds, expresses simple epithelial keratins. Thus, it appears that mesenchymal progenitor cells of developing and regenerating jaws are alike in regard to their intermediate filament content, and this may be related to nerve‐dependent growth control of progenitor cells in different developing and regenerating systems. Dev. Dyn. 1997;210:288–304. © 1997 Wiley‐Liss, Inc.

Newt cells secrete extracellular vesicles with therapeutic bioactivity in mammalian cardiomyocytes

“…viridescens newt was expanded as described [24]. Consistent with previous descriptions [13,14], A1 cells in culture demonstrated fibroblast-like morphology and stained positive for the blastemal marker 22/18 (Figure 1(a)). A1-CM is known to induce mammalian skeletal myoblast dedifferentiation along with re-entry into the cell cycle, but with limited cell proliferation [8,9].…”

Cellular response after crush injury in adult zebrafish spinal cord

“…Immunostaining was performed as described previously (Ferretti and Ghosh, 1997) by using the following primary antibodies shown to specifically recognize fish, amphibian, and human protein: anti glial fibrillary acidic protein (GFAP), rabbit polyclonal antibody (1:500, DAKO, Carpinteria, CA), anti-b III Tubulin, mouse monoclonal antibody (1:50, Sigma), anti-BrdU (1:400, Sigma), anti caspase-3 goat polyclonal (1:100, Santa Cruz Biotechnology, Santa Cruz, CA), anti NeuroD (1:100, Santa Cruz), and anti Hu C/D (1:50, Molecular Probes, Eugene, OR). Briefly, sections were rehydrated and given several washes in Phosphate buffered saline (PBS) with 0.1% Tween-20 or Triton X 100 (PBST).…”

Amphibians as research models for regenerative medicine

“…Firstly, the cytokeratin NvKII is expressed by the wound epidermis of regenerating newt limbs, but not regenerating jaws. 79 Secondly, RA fails to proximalize the blastema cells of the regenerating mandible, but does induce truncation of the regenerating maxilla with a cleft lip and palate morphology. 81 Lastly, blastema formation in the amputated mandible is not dependent on innervation.…”

“…75,[77][78][79][80] Jaw regeneration takes longer than limb regeneration, about 24 weeks compared to only 4-6 weeks for the limb. Only the tooth bearing skeletal element, the dentary of the maxilla and mandible, is ossified 5 months after amputation.…”

“…75,76 The blastema cells for mandibular regeneration are derived primarily from dedifferentiating muscle 75 and are much like those of the limb, while cartilage also contributes to the maxillary blastema. 79 The density of the blastema cells is highest on the cut ends of the mandible, where the alveolar bone, dental lamina, teeth and extra tooth buds are regenerated. The intermandibular blastema cells regenerate the muscle and connective tissue of the mandible, but the tongue and hyoid bone are not regenerated.…”