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Chikafumi Chiba – One of the best experts on this subject based on the ideXlab platform.

  • Implications of a Multi-Step Trigger of Retinal Regeneration in the Adult Newt.
    Biomedicines, 2017
    Co-Authors: Hirofumi Yasumuro, Keisuke Sakurai, Fubito Toyama, Fumiaki Maruo, Chikafumi Chiba
    Abstract:

    The Newt is an amazing four-limbed vertebrate that can regenerate various body parts including the retina. In this animal, when the neural retina (NR) is removed from the eye by surgery (retinectomy), both the NR and the retinal pigment epithelium (RPE) eventually regenerate through the process of reprogramming and proliferation of RPE cells. Thus far, we have pursued the onset mechanism of Adult Newt retinal regeneration. In this study, using an in vitro system, we found that both mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) kinase (MEK)-ERK and β-catenin were involved in cell cycle re-entry of RPE cells. MEK-ERK signaling activity in RPE cells was strengthened by retinectomy, and nuclear translocation of β-catenin in RPE cells was induced by attenuation of cell–cell contact, which was promoted by incision of the RPE or its treatment with ethylene glycol tetraacetic acid (EGTA). EGTA is a Ca2+ chelator that disrupts cadherin-mediated cell–cell adheadhesion. Reinforcement of MEK-ERK signaling activity was a prerequisite for nuclear translocation of β-catenin. These results suggest that retinectomy followed by attenuation of cell–cell contact may trigger cell cycle re-entry of RPE cells. This study, together with our previous findings concerning the proliferation and multipotency of Adult Newt RPE cells, provides insight into the mechanism of the multi-step trigger in which the onset of retinal regeneration in the Adult Newt is rigorously controlled.

  • A Transcriptome for the Study of Early Processes of Retinal Regeneration in the Adult Newt, Cynops pyrrhogaster
    , 2016
    Co-Authors: Kenta Nakamura, Hirofumi Yasumuro, Fubito Toyama, Wataru Inami, Md. Rafiqul Islam, Miyako Takayanagi, Ailidana Kunahong, Roman M. Casco-robles, Chikafumi Chiba
    Abstract:

    Retinal regeneration in the Adult Newt is a useful system to uncover essential mechanisms underlying the regeneration of body parts of this animal as well as to find clues to treat retinal disorders such as proliferative vitreoretinopathy. Here, to facilitate the study of early processes of retinal regeneration, we provide a de novo assembly transcriptome and inferred proteome of the Japanese fire bellied Newt (Cynops pyrrhogaster), which was obtained from eyeball samples of day 0–14 after surgical removal of the lens and neural retina. This transcriptome (237,120 in silico transcripts) contains most information of cDNAs/ESTs which has been reported in Newts (C. pyrrhogaster, Pleurodeles waltl and Notophthalmus viridescence) thus far. On the other hand, de novo assembly transcriptomes reported lately for N. viridescence only covered 16–31 % of this transcriptome, suggesting that most constituents of this transcriptome are specific to the regenerating eye tissues of C. pyrrhogaster. A total of 87,102 in silico transcripts of this transcriptome were functionally annotated. Coding sequence prediction in combination with functional annotation revealed that 76,968 in silico transcripts encode protein/ peptides recorded in public databases so far, whereas 17,316 might be unique. qPCR and Sanger sequencing demonstrated that this transcriptome contains much information pertaining to genes that are regulated in association with cell reprogramming, cell-cycle re-entry/proliferation, and tissue patterning in an early phase of retinal regeneration. This data also provides important insight for further investigations addressing cellular mechanisms and molecular network

  • Expression of Two Classes of Pax6 Transcripts in Reprogramming Retinal Pigment Epithelium Cells of the Adult Newt
    Zoological science, 2016
    Co-Authors: Wataru Inami, Hirofumi Yasumuro, Fubito Toyama, Fumiaki Maruo, Kenta Nakamura, Rafiqul Islam, Taro Yoshikawa, Martin Miguel Casco-robles, Chikafumi Chiba
    Abstract:

    The Adult Newt has the remarkable ability to regenerate a functional retina from retinal pigment epithelium (RPE) cells, even when the neural retina (NR) is completely lost from the eye. In this system, RPE cells are reprogrammed into a unique state of multipotent cells, named RPESCs, in an early phase of retinal regeneration. However, the signals that trigger reprogramming remain unknown. Here, to approach this issue we focused on Pax6, a transcription factor known to be expressed in RPESCs. We first identified four classes (v1, v2, v3 and v4) of Pax6 variants in the eye of Adult Newt, Cynops pyrrhogaster. These variants were expressed in most tissues of the intact eye in different combinations but not in the RPE, choroid or sclera. On the basis of this information, we investigated the expression of Pax6 in RPE cells after the NR was removed from the eye by surgery (retinectomy), and found that two classes (v1 and v2) of Pax6 variants were newly expressed in RPE cells 10 days after retinectomy, both in vivo and in vitro (RLEC system). In the RLEC system, we found that Pax6 expression is mediated through a pathway separate from the MEK-ERK pathway, which is required for cell cycle re-entry of RPE cells. These results predict the existence of a pathway that may be of fundamental importance to a better understanding of the reprogramming of RPE cells in vivo.

Panagiotis A. Tsonis – One of the best experts on this subject based on the ideXlab platform.

  • Regeneration of retinotectal projections after optic tectum removal in Adult Newts.
    Molecular vision, 2007
    Co-Authors: Mitsumasa Okamoto, Hatsuki Ohsawa, Toshinori Hayashi, Katsushi Owaribe, Panagiotis A. Tsonis
    Abstract:

    PURPOSE When injured, the Adult Newt possesses the remarkable capability to regenerate tissues and organs with return of function and physiology. One example is the Newt eye, in which regeneration can restore normal vision if the retina or lens has been removed. We wanted to examine how the retinotectal projections regenerate after removal of the brain’s optic tectum and establish this animal as a model for retinal projection as well as a central nervnervous system regeregeneration model. METHODS A major portion of the left optic tectum was removed in several Adult Newts, and the animals were monitored postoperatively for eight months to observe regeneration and innervation. Cell proliferation was examined by histological methods and by BrdU incorporation. RESULTS We observed that Adult Newts have the capability to the excised optic tectum. As indicated by horseradish peroxidase staining, 80% of the retinotectal projection area was regenerated eight months after the operation, even though the wound closed much earlier. Our study provides the first quantitation of regeneration of the retinotectal projections. The ependymal cells that line the ventricle were the most likely source of the regenerated tectum. After removal, cell proliferation was detected only in the ependymal cells layer. Double staining of proliferating cells and neurons was limited, indicating that direct transition of ependymal cells is a possibility. CONCLUSIONS The retinotectal projections after removal of the Adult Newt optic tectum can be readily re-established. Thus, this model can become indispensable for the study of vision restoration and neurogenesis.

  • Identification of MicroRNAs and Other Small RNAs from the Adult Newt Eye
    Molecular vision, 2006
    Co-Authors: Evgeny Makarev, Jason R. Spence, Katia Del Rio-tsonis, Panagiotis A. Tsonis
    Abstract:

    Purpose: MicroRNAs (miRNAs) are capable of controlling gene expression by targeting complimentary sequences in many mRNAs. Thus, a small number of miRNAs are capable of regulating expression of many different genes. miRNAs have been found in all animals from Drosophila to human and they are highly conserved. This work was undertaken in order to identify such RNAs in the Newt eye. Methods: Cloning of these RNAs was attempted after isolating and fractionating total RNA from the Adult Newt eye. A gel slice ranging from about 15 to30 nucleotides in length was cut and the extracted RNA was cloned after several processes involving reverse transcription and linker addition. For expression analysis and verification during the process of lens regeneration we used as a probe mir-124a. Results: Several microRNAs, piRNAs and other small RNAS were identified. Some of them have eye specific gene targets in other species, but for many a function in the eye remains to be attributed. Expression of miR-124a showed an interesting regulation in the lens regeneration-competent dorsal iris. Conclusions: The cloned miRNAs and other small RNAs are the first to be reported for this animal and might bear significance in regulating processes that are unique to the Newt eye, i.e., regeneration of the lens and retina.

  • A spontaneous melanoma-like tumor in the Adult Newt Triturus cristatus.
    Tumour biology : the journal of the International Society for Oncodevelopmental Biology and Medicine, 1991
    Co-Authors: Nicolaos P. Zilakos, Panagiotis A. Tsonis
    Abstract:

    We present here a case of a spontaneous melanoma-like tumor in the Adult Newt Triturus cristatus, lying above the scapula. The melanized cellular mass had infiltrated the subcutaneous connective tissu

Jean-marie Cabelguen – One of the best experts on this subject based on the ideXlab platform.

  • EPAXIAL AND LIMB MUSCLE ACTIVITY DURING SWIMMING AND TERRESTRIAL STEPPING IN THE Adult Newt, PLEURODELES WALTL
    Journal of Neurophysiology, 1997
    Co-Authors: Isabelle Delvolvé, Jean-marie Cabelguen
    Abstract:

    Delvolve, Isabelle, Tiaza Bem, and Jean-Marie Cabelguen. Epaxial and limb muscle activity during swimming and terrestrial stepping in the Adult Newt, Pleurodeles waltl. J. Neurophysiol. 78: 638–650, 1997. We have investigated the patterns of activation of epaxial musculature during both swimming and overground stepping in an Adult Newt ( Pleurodeles waltl ) with the use of electromyographic (EMG) recordings from different sites of the myomeric muscle dorsalis trunci along the body axis. The locomotor patterns of some limb muscles have also been investigated. During swimming, the epaxial myomeres are rhythmically active, with a strict alternation between opposite myomeres located at the same longitudinal site. The pattern of intersegmental coordination consists of three successively initiated waves of EMG activity passing posteriorly along the anterior trunk, the midtrunk, and the posterior trunk, respectively. Swimming is also characterized by a tonic activation of forelimb (dorsalis scapulae and extensor ulnae) and hindlimb (puboischiotibialis and puboischiofemoralis internus) muscles and a rhythmic activation of muscles (latissimus dorsi and caudofemoralis) acting both on limb and body axis. The latter matched the activation pattern of epaxial myomeres at the similar vertebral level. During overground stepping, the midtrunk myomeres express single synchronous bursts whereas the myomeres of the anterior trunk and those of the posterior trunk display a double bursting pattern in the form of two waves of EMG activity propagating in opposite directions. During overground stepping, the limb muscles and muscles acting on both limb and body axis were found to be rhythmically active and usually displayed a double bursting pattern. The main conclusion of this investigation is that the patterns of intersegmental coordination during both swimming and overground stepping in the Adult Newt are related to the presence of limbs and that they can be considered as hybrid lampreylike patterns. Thus it is hypothesized that, in Newt, a chain of coupled segmental oscillatory networks, similar to that which constitutes the central pattpattern generator (CPG) for swimming in the lamprey, can account for both trunk motor patterns if it is influenced by limb CPGs in a way depending on the locomotor mode. During swimming, the segmental networks located close to the girdles receive extra tonic excitation coming from the limb CPGs, whereas during stepping, the axial CPGs are entrained to some extent by the limb oscillators.

  • EPAXIAL AND LIMB MUSCLE ACTIVITY DURING SWIMMING AND TERRESTRIAL STEPPING IN THE Adult Newt, PLEURODELES WALTL
    Journal of neurophysiology, 1997
    Co-Authors: Isabelle Delvolvé, Tiaza Bem, Jean-marie Cabelguen
    Abstract:

    Delvolve, Isabelle, Tiaza Bem, and Jean-Marie Cabelguen. Epaxial and limb muscle activity during swimming and terrestrial stepping in the Adult Newt, Pleurodeles waltl. J. Neurophysiol. 78: 638–650…

Roy A Tassava – One of the best experts on this subject based on the ideXlab platform.

Kenta Nakamura – One of the best experts on this subject based on the ideXlab platform.

  • A Transcriptome for the Study of Early Processes of Retinal Regeneration in the Adult Newt, Cynops pyrrhogaster
    , 2016
    Co-Authors: Kenta Nakamura, Hirofumi Yasumuro, Fubito Toyama, Wataru Inami, Md. Rafiqul Islam, Miyako Takayanagi, Ailidana Kunahong, Roman M. Casco-robles, Chikafumi Chiba
    Abstract:

    Retinal regeneration in the Adult Newt is a useful system to uncover essential mechanisms underlying the regeneration of body parts of this animal as well as to find clues to treat retinal disorders such as proliferative vitreoretinopathy. Here, to facilitate the study of early processes of retinal regeneration, we provide a de novo assembly transcriptome and inferred proteome of the Japanese fire bellied Newt (Cynops pyrrhogaster), which was obtained from eyeball samples of day 0–14 after surgical removal of the lens and neural retina. This transcriptome (237,120 in silico transcripts) contains most information of cDNAs/ESTs which has been reported in Newts (C. pyrrhogaster, Pleurodeles waltl and Notophthalmus viridescence) thus far. On the other hand, de novo assembly transcriptomes reported lately for N. viridescence only covered 16–31 % of this transcriptome, suggesting that most constituents of this transcriptome are specific to the regenerating eye tissues of C. pyrrhogaster. A total of 87,102 in silico transcripts of this transcriptome were functionally annotated. Coding sequence prediction in combination with functional annotation revealed that 76,968 in silico transcripts encode protein/ peptides recorded in public databases so far, whereas 17,316 might be unique. qPCR and Sanger sequencing demonstrated that this transcriptome contains much information pertaining to genes that are regulated in association with cell reprogramming, cell-cycle re-entry/proliferation, and tissue patterning in an early phase of retinal regeneration. This data also provides important insight for further investigations addressing cellular mechanisms and molecular network

  • Expression of Two Classes of Pax6 Transcripts in Reprogramming Retinal Pigment Epithelium Cells of the Adult Newt
    Zoological science, 2016
    Co-Authors: Wataru Inami, Hirofumi Yasumuro, Fubito Toyama, Fumiaki Maruo, Kenta Nakamura, Rafiqul Islam, Taro Yoshikawa, Martin Miguel Casco-robles, Chikafumi Chiba
    Abstract:

    The Adult Newt has the remarkable ability to regenerate a functional retina from retinal pigment epithelium (RPE) cells, even when the neural retina (NR) is completely lost from the eye. In this system, RPE cells are reprogrammed into a unique state of multipotent cells, named RPESCs, in an early phase of retinal regeneration. However, the signals that trigger reprogramming remain unknown. Here, to approach this issue we focused on Pax6, a transcription factor known to be expressed in RPESCs. We first identified four classes (v1, v2, v3 and v4) of Pax6 variants in the eye of Adult Newt, Cynops pyrrhogaster. These variants were expressed in most tissues of the intact eye in different combinations but not in the RPE, choroid or sclera. On the basis of this information, we investigated the expression of Pax6 in RPE cells after the NR was removed from the eye by surgery (retinectomy), and found that two classes (v1 and v2) of Pax6 variants were newly expressed in RPE cells 10 days after retinectomy, both in vivo and in vitro (RLEC system). In the RLEC system, we found that Pax6 expression is mediated through a pathway separate from the MEK-ERK pathway, which is required for cell cycle re-entry of RPE cells. These results predict the existence of a pathway that may be of fundamental importance to a better understanding of the reprogramming of RPE cells in vivo.

  • A transcriptome for the study of early processes of retinal regeneration in the Adult Newt, Cynops pyrrhogaster.
    PloS one, 2014
    Co-Authors: Kenta Nakamura, Hirofumi Yasumuro, Fubito Toyama, Wataru Inami, Rafiqul Islam, Miyako Takayanagi, Ailidana Kunahong, Roman M. Casco-robles, Chikafumi Chiba
    Abstract:

    Retinal regeneration in the Adult Newt is a useful system to uncover essential mechanisms underlying the regeneration of body parts of this animal as well as to find clues to treat retinal disorders such as proliferative vitreoretinopathy. Here, to facilitate the study of early processes of retinal regeneration, we provide a de novo assembly transcriptome and inferred proteome of the Japanese fire bellied Newt (Cynops pyrrhogaster), which was obtained from eyeball samples of day 0–14 after surgical removal of the lens and neural retina. This transcriptome (237,120 in silico transcripts) contains most information of cDNAs/ESTs which has been reported in Newts (C. pyrrhogaster, Pleurodeles waltl and Notophthalmus viridescence) thus far. On the other hand, de novo assembly transcriptomes reported lately for N. viridescence only covered 16–31% of this transcriptome, suggesting that most constituents of this transcriptome are specific to the regenerating eye tissues of C. pyrrhogaster. A total of 87,102 in silico transcripts of this transcriptome were functionally annotated. Coding sequence prediction in combination with functional annotation revealed that 76,968 in silico transcripts encode protein/peptides recorded in public databases so far, whereas 17,316 might be unique. qPCR and Sanger sequencing demonstrated that this transcriptome contains much information pertaining to genes that are regulated in association with cell reprogramming, cell-cycle re-entry/proliferation, and tissue patterning in an early phase of retinal regeneration. This data also provides important insight for further investigations addressing cellular mechanisms and molecular networks underlying retinal regeneration as well as differences between retinal regeneration and disorders. This transcriptome can be applied to ensuing comprehensive gene screening steps, providing candidate genes, regardless of whether annotated or unique, to uncover essential mechanisms underlying early processes of retinal regeneration.