Wnt, Ptk7, and FGFRL expression gradients control trunk positional identity in planarian regeneration
- Northwestern University, United States
Abstract
Mechanisms enabling positional identity re-establishment are likely critical for tissue regeneration. Planarians use Wnt/beta-catenin signaling to polarize the termini of their anteroposterior axis, but little is known about how regeneration signaling restores regionalization along body or organ axes. We identify three genes expressed constitutively in overlapping body-wide transcriptional gradients that control trunk-tail positional identity in regeneration. ptk7 encodes a trunk-expressed kinase-dead Wnt co-receptor, wntP-2 encodes a posterior-expressed Wnt ligand, and ndl-3 encodes an anterior-expressed homolog of conserved FGFRL/nou-darake decoy receptors. ptk7 and wntP-2 maintain and allow appropriate regeneration of trunk tissue position independently of canonical Wnt signaling and with suppression of ndl-3 expression in the posterior. These results suggest that restoration of regional identity in regeneration involves the interpretation and re-establishment of axis-wide transcriptional gradients of signaling molecules.
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© 2016, Lander & Petersen
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Wnt, Ptk7, and FGFRL expression gradients control trunk positional identity in planarian regeneration
eLife 5:e12850.
https://doi.org/10.7554/eLife.12850
Further reading
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- Stem Cells and Regenerative Medicine
Tissue necrosis is a devastating complication for many human diseases and injuries. Unfortunately, our understanding of necrosis and how it impacts surrounding healthy tissue – an essential consideration when developing effective methods to treat such injuries – has been limited by a lack of robust genetically tractable models. Our lab previously established a method to study necrosis-induced regeneration in the Drosophila wing imaginal disc, which revealed a unique phenomenon whereby cells at a distance from the injury upregulate caspase activity in a process called Necrosis-induced Apoptosis (NiA) that is vital for regeneration. Here, we have further investigated this phenomenon, showing that NiA is predominantly associated with the highly regenerative pouch region of the disc, shaped by genetic factors present in the presumptive hinge. Furthermore, we find that a proportion of NiA fail to undergo apoptosis, instead surviving effector caspase activation to persist within the tissue and stimulate reparative proliferation late in regeneration. This proliferation relies on the initiator caspase Dronc, and occurs independent of JNK, ROS or mitogens associated with the previously characterized Apoptosis-induced Proliferation (AiP) mechanism. These data reveal a new means by which non-apoptotic Dronc signaling promotes regenerative proliferation in response to necrotic damage.
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- Stem Cells and Regenerative Medicine
Background:
In idiopathic pulmonary fibrosis (IPF) patients, alveolar architectures are lost and gas transfer function would decline, which cannot be rescued by conventional anti-fibrotic therapy. P63+ lung basal progenitor cells are reported to have potential to repair damaged lung epithelium in animal models, which need further investigation in clinical trials.
Methods:
We cloned and expanded P63+ progenitor cells from IPF patients to manufacture cell product REGEND001, which were further characterized by morphology and single-cell transcriptomic analysis. Subsequently, an open-label, dose-escalation autologous progenitor cell transplantation clinical trial was conducted. We treated 12 patients with ascending doses of cells: 0.6x, 1x, 2x and 3.3x106 cells/kg bodyweight. The primary outcome was the incidence and severity of cell therapy-related adverse events (AEs); secondary outcome included other safety and efficacy evaluations.
Results:
P63+ basal progenitor cell was safe and tolerated at all doses, with no dose-limiting toxicity or cell therapy-related severe adverse events observed. Patients in three higher dose groups showed significant improvement of lung gas transfer function as well as exercise ability. Resolution of honeycomb lesion was observed in patients of higher dose groups.
Conclusions:
REGEND001 has high safety profile and meanwhile encourages further efficacy exploration in IPF patients.
Funding:
National High Level Hospital Clinical Research Funding (2022-PUMCH-B-108), National Key Research and Development Plan (2024YFA1108900, 2024YFA1108500), Jiangsu Province Science and Technology Special Project Funding (BE2023727), National Biopharmaceutical Technology Research Project Funding (NCTIB2023XB01011), Non-profit Central Research Institute Fund of Chinese Academy of Medical Science (2020-PT320-005), and Regend Therapeutics.
Clinical trial number:
Chinese clinical trial registry: CTR20210349.
