Biology subjects

Agata, K.

Publications and source records attributed to Agata, K..

7 recordsLinked to original sources

bioRxiv2023

ECM degradation in the stump region induced by Fgf during functional joint regeneration in frogs

Previous studies indicated the importance of the reciprocal interactions between residual tissues in the stump and the newly formed blastema for achieving functional joint regeneration after amputation at the joint level in newts. This reciprocal interaction during regeneration was named "reintegration". When this reintegration mechanism was evoked in Xenopus leavis, regeneration of a functional joint was induced in frogs. Interestingly, degradation of extracellular matrix (ECM) in the remaining joint cartilage was observed during regeneration in both newts and frogs. Histological and gene expression analyses suggested that the degradation of Type II collagen in the cartilage of the articular head might be performed by matrix metalloproteases (Mmps) which were transiently expressed after amputation. We found that fibroblast growth factor (Fgf) induced Mmps expression in the cartilage of the articular head. These results support the possibility that the Fgf signal induces ECM degradation in joint tissues via Mmps expression and that the ECM degradation and subsequent bone morphogenetic protein (Bmp) secretion promote cell proliferation, migration, and differentiation of the cells in the blastema to achieve functional joint regeneration.

developmental biology↗

bioRxiv2023

Fgf10 mutant newts can regenerate normal limbs despite severe developmental hindlimb defects

In the amniote limb, FGF10 is essential for limb bud initiation and outgrowth. However, whether this function is broadly conserved in tetrapods and/or involved in adult limb regeneration remains unknown. To tackle this question, we established an Fgf10 null mutant line in the newt Pleurodeles waltl which have amazing regenerative ability. While Fgf10 mutant forelimbs develop normally, the hindlimbs exhibit severe digit reduction, fail to ossify the zeugopod, and downregulate FGF target genes like Sall1, Runx1 and Hoxa11/d11. Despite these developmental defects, Fgf10 mutants were able to regenerate near-normal hindlimbs. Together, our results suggest an important role for Fgf10 in hindlimb digit formation and zeugopod ossification during development, but little or no function in regeneration, suggesting that different mechanisms operate during limb regeneration versus development.

developmental biology↗

bioRxiv2021

Fluctuation of cellular differentiation in limb regeneration is regulated by Pde4b in urodele amphibians

Urodele amphibians, Pleurodeles waltl and Ambystoma mexicanum, have organ-level regeneration capability, such as limb regeneration. Multipotent cells are induced by an endogenous mechanism in amphibian limb regeneration. It is well known that dermal fibroblasts receive regenerative signals and turn into multipotent cells, called blastema cells. However, the induction mechanism of the blastema cells from matured dermal cells was unknown. We previously found that BMP2, FGF2, and FGF8 (B2FF) could play sufficient roles in blastema induction in urodele amphibians. Here, we show that B2FF treatment can induce dermis-derived cells that can participate in multiple cell lineage in limb regeneration. We first established a newt dermis-derived cell line and confirmed that B2FF treatment on the newt cells provided plasticity in cellular differentiation in limb regeneration. Interspecies comparative analysis clarified that Pde4b upregulation by B2FF specifically took place in the newt cells. Blocking PDE4B signaling by Rolipram suppressed dermis-to-cartilage transformation and the mosaic knockout animals showed consistent results. Our results are a valuable insight into how dermal fibroblasts acquire multipotency during the early phase of limb regeneration via an endogenous program in amphibian limb regeneration.

developmental biology↗

bioRxiv2021

Proliferation maintains the undifferentiated status of stem cells: the role of the planarian cell cycle regulator Cdh1

The coincidence of cell cycle arrest and differentiation has been described in a wide variety of stem cells and organisms for decades, but the causal relationship is still unclear due to the complicated regulation of the cell cycle. Here, we used the planarian Dugesia japonica since it possesses a quite simple cell cycle regulation in which cdh1 is the only factor that arrests the cell cycle. When cdh1 was functionally inhibited, the planarians could not maintain their tissue homeostasis and could not regenerate their missing body parts. While the ablation of cdh1 caused pronounced propagation of the stem cells, the progenitor and differentiated cells were decreased. Further analysis indicated that the stem cells without cdh1 expression did not undergo differentiation even though they received ERK signaling activation as an induction signal. These results suggested that stem cells could not acquire differentiation competence without cell cycle arrest. Thus, we propose that cell cycle regulation determines the differentiation competence and that cell cycle exit to G0 enables stem cells to undergo differentiation. Summary statementBy using planarians, which have quite simple cell cycle regulation, we revealed that stem cells with cell cycle progression could not undergo differentiation even though an induction signal was activated.

developmental biology↗

bioRxiv2019

The roles of hox 13 genes in newt limb development and regeneration

Posterior Hox genes play crucial roles in limb development and specify regions in the proximal-distal (PD) axis of limbs. However, there is no direct genetic evidence that Hox genes are essential for limb regeneration. Moreover, if essential, it is totally unknown which Hox genes have the same or distinct functions between development and regeneration. Here, we mutated hox13 using an efficient CRISPR/Cas9 system in newts (Pleurodeles waltl), which have strong regenerative capacities in various tissues. Triple or double mutants of hox13 paralogs lost their digit and metacarpal/metatarsal bones. Limb regeneration progressed but regenerates lacked the same autopod region. These results showed that hox13 paralogs have the same functions in limb development and regeneration.

developmental biology↗

bioRxiv2019

ECM-body: A cell-free 3D biomimetic scaffold derived from intact planarian body

Extracellular matrix (ECM) plays key roles in shaping fates of stem cells, not only by providing suitable niche but also by mediating physical and biochemical cues. Despite intensive investigations on regeneration, the roles of ECM on fate determination of stem cells in animal with great regenerative potency, such as planarian, remained unclear. Here, we developed a method to decellularizing and isolating extracellular matrix from planarians. Although the isolated scaffold appears translucent, it contains all the internal features, resembling the structure of intact planarian, and which we thus called \"ECM-body\". Nuclear staining demonstrated that ECM-body contains very little or no cell remained. Histological sections displayed a well-preserved morphological integrity of the specimen. Scanning electron microscope showed porous surface on ECM-body, potentially suitable for housing cells. Furthermore, our preliminary experiment suggested that ECM-body can be utilized as biomimetic scaffold for cell culture as it may support survival of injected neoblasts.

developmental biology↗

bioRxiv2018

A comprehensive reference transcriptome resource for the Iberian ribbed newt Pleurodeles waltl, an emerging model for developmental and regeneration biology

Urodele amphibian newts have unique biological properties, notably including prominent regeneration ability. Iberian ribbed newt, Pleurodeles waltl, is a promising model newt along with the successful development of the easy breeding system and efficient transgenic and genome editing methods. However, genetic information of P. waltl was limited. In the present study, we conducted an intensive transcriptome analysis of P. waltl using RNA-sequencing to build gene models and annotate them. We generated 1.2 billion Illumina reads from a wide variety of samples across 11 different tissues and 9 time points during embryogenesis. They were assembled into 202,788 non-redundant contigs that appear to cover nearly complete (~98%) P. waltl protein-coding genes. Using the gene set as a reference, our gene network analysis identified regeneration-, developmental-stage-, and tissue-specific co-expressed gene modules. Ortholog analyses with other vertebrates revealed the gene repertoire evolution of amphibians which includes urodele-specific loss of bmp4 and duplications of wnt11b. Our transcriptome resource will enhance future research employing this emerging model animal for regeneration research as well as other areas such as developmental biology, stem cell biology, cancer research, ethology and toxico-genomics. These data are available via our portal website, iNewt (http://www.nibb.ac.jp/imori/main/).

genomics↗