Signaling networks organizing regenerative growth of the zebrafish fin
Daniel Wehner,
Gilbert Weidinger
Trends in Genetics
31
(6)
336-343
(2015)
| Journal
In contrast to mammals, adult salamanders and fish can completely regenerate their appendages after amputation. The cellular and molecular mechanisms underlying this fascinating phenomenon are beginning to emerge, including substantial progress in the identification of signals that control regenerative growth of the zebrafish caudal fin. Despite the fairly simple architecture of the fin, the regulation of its regeneration is complex. Many signals, including fibroblast growth factor (FGF), Wnt, Hedgehog (Hh), retinoic acid (RA), Notch, bone morphogenic protein (BMP), activin, and insulin-like growth factor (IGF), are required for regeneration. Much work needs to be done to dissect tissue-specific functions of these pathways and how they interact, but Wnt/beta-catenin signaling is already emerging as a central player. Surprisingly, Wnt/beta-catenin signaling appears to largely indirectly control epidermal patterning, progenitor cell proliferation, and osteoblast maturation via regulation of a multitude of secondary signals.
Use of the TetON System to Study Molecular Mechanisms of Zebrafish Regeneration
Daniel Wehner,
Christopher Jahn,
Gilbert Weidinger
Journal of Visualized Experiments
(100)
e52756
(2015)
| Journal
The zebrafish has become a very important model organism for studying vertebrate development, physiology, disease, and tissue regeneration. A thorough understanding of the molecular and cellular mechanisms involved requires experimental tools that allow for inducible, tissue-specific manipulation of gene expression or signaling pathways. Therefore, we and others have recently adapted the TetON system for use in zebrafish. The TetON system facilitates temporally and spatially-controlled gene expression and we have recently used this tool to probe for tissue-specific functions of Wnt/beta-catenin signaling during zebrafish tail fin regeneration. Here we describe the workflow for using the TetON system to achieve inducible, tissue-specific gene expression in the adult regenerating zebrafish tail fin. This includes the generation of stable transgenic TetActivator and TetResponder lines, transgene induction and techniques for verification of tissue-specific gene expression in the fin regenerate. Thus, this protocol serves as blueprint for setting up a functional TetON system in zebrafish and its subsequent use, in particular for studying fin regeneration.
A Polyphenylene Dendrimer Drug Transporter with Precisely Positioned Amphiphilic Surface Patches
Rene Stangenberg,
Yuzhou Wu,
Jana Hedrich,
Dennis Kurzbach,
Daniel Wehner,
Gilbert Weidinger,
Seah Ling Kuan,
Malin Insa Jansen,
Fedor Jelezko,
Heiko J. Luhmann,
Dariush Hinderberger,
Tanja Weil,
Klaus Muellen
The design and synthesis of a polyphenylene dendrimer (PPD 3) with discrete binding sites for lipophilic guest molecules and characteristic surface patterns is presented. Its semi-rigidity in combination with a precise positioning of hydrophilic and hydrophobic groups at the periphery yields a refined architecture with lipophilic binding pockets that accommodate defined numbers of biologically relevant guest molecules such as fatty acids or the drug doxorubicin. The size, architecture, and surface textures allow to even penetrate brain endothelial cells that are a major component of the extremely tight blood-brain barrier. In addition, low to no toxicity is observed in in vivo studies using zebrafish embryos. The unique PPD scaffold allows the precise placement of functional groups in a given environment and offers a universal platform for designing drug transporters that closely mimic many features of proteins.
beta-Catenin-Dependent Control of Positional Information along the AP Body Axis in Planarians Involves a Teashirt Family Member
Hanna Reuter,
Martin Maerz,
Matthias C. Vogg,
David Eccles,
Laura Grifol-Boldu,
Daniel Wehner,
Suthira Owlarn,
Teresa Adell,
Gilbert Weidinger,
Kerstin Bartscherer
Wnt/beta-catenin signaling regulates tissue homeostasis and regeneration in metazoans. In planarians-flatworms with high regenerative potential-Wnt ligands are thought to control tissue polarity by shaping a beta-catenin activity gradient along the anterior-posterior axis, yet the downstream mechanisms are poorly understood. We performed an RNA sequencing (RNA-seq)-based screen and identified hundreds of beta-catenin-dependent transcripts, of which several were expressed in muscle tissue and stem cells in a graded fashion. In particular, a teashirt (tsh) ortholog was induced in a beta-catenin-dependent manner during regeneration in planarians and zebrafish, and RNAi resulted in two-headed planarians. Strikingly, intact planarians depleted of tsh induced anterior markers and slowly transformed their tail into a head, reminiscent of beta-catenin RNAi phenotypes. Given that beta-catenin RNAi enhanced the formation of muscle cells expressing anterior determinants in tail regions, our study suggests that this pathway controls tissue polarity through regulating the identity of differentiating cells during homeostasis and regeneration.
Contact
Research Group Daniel Wehner
Max-Planck-Zentrum für Physik und Medizin Kussmaulallee 2 91054 Erlangen, Germany
