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Biology subjects

Abouelela, A.

Publications and source records attributed to Abouelela, A..

3 recordsLinked to original sources

Pancreatic injury induces β-cell regeneration in axolotl

BackgroundDiabetes is a condition characterized by a loss of pancreatic {beta}-cell function which results in the dysregulation of insulin homeostasis. Using a partial pancreatectomy model in axolotl, we aimed to observe the pancreatic response to injury. ResultsHere we show a comprehensive histological assessment of pancreatic islets in axolotl. Following pancreatic injury, no apparent blastemal structure was observed. We found a significant, organ-wide increase in cellular proliferation post-resection in the pancreas compared to sham-operated controls. This proliferative response was most robust at the site of injury. We found that {beta}-cells actively contributed to the increased rates of proliferation upon injury. {beta}-cell proliferation manifested in increased {beta}-cell mass in injured tissue at two weeks post injury. At four weeks post injury, we found organ-wide proliferation to be extinguished while proliferation at the injury site persisted, corresponding to pancreatic tissue recovery. Similarly, total {beta}-cell mass was comparable to sham after four weeks. ConclusionsOur findings suggest a non-blastema-mediated regeneration process takes place in the pancreas, by which pancreatic resection induces whole-organ {beta}-cell proliferation without the formation of a blastemal structure. This process is analogous to other models of compensatory growth in axolotl, including liver regeneration.

developmental biology↗

An evolutionarily conserved role for VEGF signaling in the expansion of non-vascular tissue during regeneration.

Salamanders are capable of regenerating whole limbs throughout life, a feat that is unmatched within tetrapods. Limb regeneration is dependent upon the formation of a blastema, which contains undifferentiated cells capable of giving rise to most cells of the regenerated limb. Innervation is required for regeneration, along with many signaling pathways, including FGF, BMP and Wnt, but the role of VEGF signaling during salamander limb regeneration is not well understood. Here we show that VEGF signaling is essential for limb regeneration and that blastema cells and limb fibroblasts display impaired proliferation in the absence of VEGF signaling. By performing analogous experiments in planaria, which lack vasculature, we show a potential evolutionarily conserved role for VEGF in the expansion of blastema tissues that is separable from angiogenesis. Moreover, loss of VEGF signaling reduces induction of EMT-like processes, suggesting VEGF signaling functions upstream of the expression of EMT transcription factors, including Snai2. These findings highlight potential roles for VEGF signaling during regeneration which may extend beyond typical findings related to angiogenesis.

developmental biology↗

Amputation Triggers Long-Range Epidermal Permeability Changes in Evolutionarily Distant Regenerative Organisms

Previous studies have reported that amputation invokes body-wide responses in regenerative organisms, but most have not examined the implications of these changes beyond the region of tissue regrowth. Specifically, long-range epidermal responses to amputation are largely uncharacterized, with research on amputation-induced epidermal responses in regenerative organisms traditionally being restricted to the wound site. Here, we investigate the effect of amputation on long-range epidermal permeability in two evolutionarily distant, regenerative organisms: axolotls and planarians. We find that amputation triggers a long-range increase in epidermal permeability in axolotls, accompanied by a long-range epidermal downregulation in MAPK signaling. Additionally, we provide functional evidence that pharmacologically inhibiting MAPK signaling in regenerating planarians increases long-range epidermal permeability. These findings advance our knowledge of body-wide changes due to amputation in regenerative organisms and warrant further study on whether epidermal permeability dysregulation in the context of amputation may lead to pathology in both regenerative and non-regenerative organisms. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=167 SRC="FIGDIR/small/610385v2_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@81b022org.highwire.dtl.DTLVardef@52c2e9org.highwire.dtl.DTLVardef@17a5f93org.highwire.dtl.DTLVardef@118b8f6_HPS_FORMAT_FIGEXP M_FIG C_FIG

physiology↗