TAK1 inhibition increases proliferation and differentiation of chick retinal cells.

The factors necessary for the differentiation of cell types within the retina are incompletely understood. The transforming growth factor beta (TGF-β) superfamily, including TGF-β1 and 2, the bone morphogenetic proteins, and the activins have all been implicated in differentiation; however, the mechanisms by which these factors affect differentiation are only partially understood. The studies herein focus on a potential role for transforming growth factor β-activated kinase 1 (TAK1), a hub kinase that lies at the intersection of multiple signaling pathways, in the differentiation of cell types within the chick retina.

Meningeal Foam Cells and Ependymal Cells in Axolotl Spinal Cord Regeneration.

A previously unreported population of foam cells (foamy macrophages) accumulates in the invasive fibrotic meninges during gap regeneration of transected adult Axolotl spinal cord (salamander ) and may act beneficially. Multinucleated giant cells (MNGCs) also occurred in the fibrotic meninges. Actin-label localization and transmission electron microscopy showed characteristic foam cell and MNGC podosome and ruffled border-containing sealing ring structures involved in substratum attachment, with characteristic intermediate filament accumulations surrounding nuclei.

Musashi and Plasticity of and Axolotl Spinal Cord Ependymal Cells.

The differentiated state of spinal cord ependymal cells in regeneration-competent amphibians varies between a constitutively active state in what is essentially a developing organism, the tadpole of the frog , and a quiescent, activatable state in a slowly growing adult salamander , the Axolotl. Ependymal cells are epithelial in intact spinal cord of all vertebrates. After transection, body region ependymal epithelium in both and the Axolotl disorganizes for regenerative outgrowth (gap replacement).

Meckelin 3 is necessary for photoreceptor outer segment development in rat Meckel syndrome.

Ciliopathies lead to multiorgan pathologies that include renal cysts, deafness, obesity and retinal degeneration. Retinal photoreceptors have connecting cilia joining the inner and outer segment that are responsible for transport of molecules to develop and maintain the outer segment process. The present study evaluated meckelin (MKS3) expression during outer segment genesis and determined the consequences of mutant meckelin on photoreceptor development and survival in Wistar polycystic kidney disease Wpk/Wpk rat using immunohistochemistry, analysis of cell death and electron microscopy.

Matrix metalloproteinase expression during blastema formation in regeneration-competent versus regeneration-deficient amphibian limbs.

We used an antibody array to compare the protein expression of matrix metalloproteinases (MMPs)-1, -2, -3, -8, -9, -10, and -13, as well as the tissue inhibitors of metalloproteinases (TIMPs)-1, -2, and -4 during blastema formation in amputated hindlimbs of regeneration-competent wild-type axolotls and stage-54 Xenopus, and regeneration-deficient short-toes axolotls and Xenopus froglets. Expression of MMP-9 and -2 was also compared by zymography. Both short-toes and froglet failed to up-regulate MMPs in a pattern comparable to the wild-type axolotl, suggesting that subnormal histolysis is at least in part responsible for the poor blastema formation characteristic of both short-toes and froglet.

Effect of carbon nanoparticles on renal epithelial cell structure, barrier function, and protein expression.

To assess effects of carbon nanoparticle (CNP) exposure on renal epithelial cells, fullerenes (C(60)), single-walled carbon nanotubes (SWNT), and multi-walled carbon nanotubes (MWNT) were incubated with a confluent renal epithelial line for 48 h. At low concentrations, CNP-treated cells exhibited significant decreases in transepithelial electrical resistance (TEER) but no changes in hormone-stimulated ion transport or CNP-induced toxicity or stress responses as measured by lactate dehydrogenase or cytokine release. The changes in TEER, manifested as an inverse relationship with CNP concentration, were mirrored by an inverse correlation between dose and changes in protein expression.

The short toes mutation of the axolotl.

The axolotl mutant strain, short toes (s/s), can regenerate spinal cord and tail, but not limbs. This makes s/s potentially very useful for limb regeneration studies. This mutant merits a new examination that integrates the original description of the mutant, existing experimental studies, new data and current thinking about stem cells and regeneration.

Expression patterns of chick Musashi-1 in the developing nervous system.

Vertebrate homologues of musashi have recently been referred to as neural stem cell markers because of their expression patterns and RNA-binding interactions. In the context of the notch signaling pathway, Musashi-1 (Msi-1) is a regulator of neural cell generation, cooperating with notch to maintain mitosis. In an effort to identify definitive stem cell markers of the neural retina, a portion of the Msi-1 cDNA was cloned, and the expression of Msi-1 in the chick eye was analyzed.

Protein geranylgeranyltransferase I is involved in specific aspects of abscisic acid and auxin signaling in Arabidopsis.

Arabidopsis (Arabidopsis thaliana) mutants lacking a functional ERA1 gene, which encodes the beta-subunit of protein farnesyltransferase (PFT), exhibit pleiotropic effects that establish roles for protein prenylation in abscisic acid (ABA) signaling and meristem development. Here, we report the effects of T-DNA insertion mutations in the Arabidopsis GGB gene, which encodes the beta-subunit of protein geranylgeranyltransferase type I (PGGT I). Stomatal apertures of ggb plants were smaller than those of wild-type plants at all concentrations of ABA tested, suggesting that PGGT I negatively regulates ABA signaling in guard cells.

Cloning and analysis of axolotl ISL2 and LHX2 LIM-homeodomain transcription factors.

We cloned and characterized the ISL2 and LHX2 LIM-homeodomain transcription factors of the Mexican salamander, or axolotl, Ambystoma mexicanum. Using a degenerate PCR approach, partial cDNAs representing five LIM-homeodomain genes were cloned, indicating conservation of this class of transcription factors in urodeles. Full-length cDNAs for Isl2 and Lhx2 were identified and sequenced.

Extending the table of stages of normal development of the axolotl: limb development.

The existing table of stages of the normal development of the axolotl (Ambystoma mexicanum) ends just after hatching. At this time, the forelimbs are small buds. In this study, we extend the staging series through completion of development of the forelimbs and hindlimbs.

Urodele spinal cord regeneration and related processes.

Urodele amphibians, newts and salamanders, can regenerate lesioned spinal cord at any stage of the life cycle and are the only tetrapod vertebrates that regenerate spinal cord completely as adults. The ependymal cells play a key role in this process in both gap replacement and caudal regeneration. The ependymal response helps to produce a different response to neural injury compared with mammalian neural injury.

Regeneration of the urodele limb: a review.

Urodele amphibians have been widely used for studies of limb regeneration. In this article, we review studies on blastema cell proliferation and propose a model of blastemal self-organization and patterning. The model is based on local cell interactions that intercalate positional identities within circumferential and proximodistal boundaries that outline the regenerate.

Spinal cord regeneration: intrinsic properties and emerging mechanisms.

Injured spinal cord regenerates in adult fish and urodele amphibians, young tadpoles of anuran amphibians, lizard tails, embryonic birds and mammals, and in adults of at least some strains of mice. The extent of this regeneration is described with respect to axonal regrowth, neurogenesis, glial responses, and maintenance of an 'embryonic' environment. The regeneration process in amphibian spinal cord demonstrates that gap replacement and caudal regeneration share some properties with developing spinal cord.

Developmental aspects of spinal cord and limb regeneration.

The ability of birds and mammals to regenerate tissues is limited. By contrast, urodele amphibians can regenerate a variety of injured tissues such as intestine, cardiac muscle, lens and neural retina, as well as entire structures such as limbs, tail and lower jaw. This regenerative capacity is associated with the ability to form masses of mesenchyme cells (blastemas) that differentiate into the missing tissues or parts.