WNT16 antagonises excessive canonical WNT activation and protects cartilage in osteoarthritis

ObjectiveBoth excessive and insufficient activation of WNT signalling results in cartilage breakdown and osteoarthritis. WNT16 is upregulated in the articular cartilage following injury and in osteoarthritis. Here, we investigate the function of WNT16 in osteoarthritis and the downstream molecular mechanisms.MethodsOsteoarthritis was induced by destabilisation of the medial meniscus in wild-type and WNT16-deficient mice. Molecular mechanisms and downstream effects were studied in vitro and in vivo in primary cartilage progenitor cells and primary chondrocytes. The pathway downstream of WNT16 was studied in primary chondrocytes and using the axis duplication assay in Xenopus.ResultsWNT16-deficient mice developed more severe osteoarthritis with reduced expression of lubricin and increased chondrocyte apoptosis. WNT16 supported the phenotype of cartilage superficial-zone progenitor cells and lubricin expression. Increased osteoarthritis in WNT16-deficient mice was associated with excessive activation of canonical WNT signalling. In vitro, high doses of WNT16 weakly activated canonical WNT signalling, but, in co-stimulation experiments, WNT16 reduced the capacity of WNT3a to activate the canonical WNT pathway. In vivo, WNT16 rescued the WNT8-induced primary axis duplication in Xenopus embryos.ConclusionsIn osteoarthritis, WNT16 maintains a balanced canonical WNT signalling and prevents detrimental excessive activation, thereby supporting the homeostasis of progenitor cells.

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HO-1/CO Maintains Intestinal Barrier Integrity through NF-κB/MLCK Pathway in Intestinal HO-1-/- Mice

Oxidative Medicine and Cellular Longevity ◽

10.1155/2021/6620873 ◽

2021 ◽

Vol 2021 ◽

pp. 1-19

Author(s):

Zhenling Zhang ◽

Lijing Zhang ◽

Qiuping Zhang ◽

Bojia Liu ◽

Fang Li ◽

...

Keyword(s):

Molecular Mechanisms ◽

Intestinal Barrier ◽

Heme Oxygenase 1 ◽

Zinc Protoporphyrin ◽

Barrier Integrity ◽

Tnf Α ◽

Intestinal Barrier Integrity ◽

Deficient Mice

Background. Intestinal barrier injury is an important contributor to many diseases. We previously found that heme oxygenase-1 (HO-1) and carbon monoxide (CO) protect the intestinal barrier. This study is aimed at elucidating the molecular mechanisms of HO-1/CO in barrier loss. Materials and Methods. We induced gut leakiness by injecting carbon tetrachloride (CCl4) to wildtype or intestinal HO-1-deficient mice. In addition, we administrated tumor necrosis factor-α (TNF-α) to cells with gain- or loss-of-HO-1 function. The effects of HO-1/CO maintaining intestinal barrier integrity were investigated in vivo and in vitro. Results. Cobalt protoporphyrin and CO-releasing molecule-2 alleviated colonic mucosal injury and TNF-α levels; upregulated tight junction (TJ) expression; and inhibited epithelial IκB-α degradation and phosphorylation, NF-κB p65 phosphorylation, long MLCK expression, and MLC-2 phosphorylation after administration of CCl4. Zinc protoporphyrin completely reversed these effects. These findings were further confirmed in vitro, using Caco-2 cells with gain- or loss-of-HO-1-function after TNF-α. Pretreated with JSH-23 (NF-κB inhibitor) or ML-7 (long MLCK inhibitor), HO-1 overexpression prevented TNF-α-induced TJ disruption, while HO-1 shRNA promoted TJ damage even in the presence of JSH-23 or ML-7, thus suggesting that HO-1 dependently protected intestinal barrier via the NF-κB p65/MLCK/p-MLC-2 pathway. Intestinal HO-1-deficient mice further demonstrated the effects of HO-1 in maintaining intestinal barrier integrity and its relative mechanisms. Alleviated hepatic fibrogenesis and serum ALT levels finally confirmed the clinical significance of HO-1/CO repairing barrier loss in liver injury. Conclusion. HO-1/CO maintains intestinal barrier integrity through the NF-κB/MLCK pathway. Therefore, the intestinal HO-1/CO-NF-κB/MLCK system is a potential therapeutic target for diseases with a leaky gut.

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UCP2 Modulates Cell Proliferation through the MAPK/ERK Pathway during Erythropoiesis and Has No Effect on Heme Biosynthesis

Blood ◽

10.1182/blood.v112.11.5372.5372 ◽

2008 ◽

Vol 112 (11) ◽

pp. 5372-5372

Author(s):

Alvaro A Elorza ◽

Brigham B Hyde ◽

Hanna Mikkola ◽

Sheila Collins ◽

Orian S Shirihai

Keyword(s):

Cell Proliferation ◽

Progenitor Cells ◽

Fetal Liver ◽

Mitochondrial Protein ◽

Erythroid Progenitor ◽

Heme Synthesis ◽

Erythroid Progenitor Cells ◽

Deficient Mice

Abstract UCP2, an inner membrane mitochondrial protein, has been implicated in bioenergetics and Reactive Oxygen Species (ROS) modulation. UCP2 has been previously hypothesized to function as a facilitator of heme synthesis and iron metabolism by reducing ROS production. While UCP2 has been found to be induced by GATA1 during erythroid differentiation its role in erythropoiesis in vivo or in vitro has not been reported thus far. Here we report on the study of UCP2 role in erythropoiesis and the hematologic phenotype of UCP2 deficient mouse. In vivo we found that UCP2 protein peaks at early stages of erythroid maturation when cells are not fully committed in heme synthesis and then becomes undetectable at the reticulocyte stage. Iron incorporation into heme was unaltered in erythroid cells from UCP2 deficient mice. While heme synthesis was not influenced by UCP2 deficiency, mice lacking UCP2 had a delayed recovery from chemically induced hemolytic anemia. Analysis of the erythroid lineage from bone marrow and fetal liver revealed that in the UCP2 deficient mice the R3 (CD71high/Ter119high) population was reduced by 24%. The count of BFU-E and CFU-E colonies, scored in an erythroid colony assay, was unaffected, indicating an equivalent number of early erythroid progenitor cells in both UCP2 deficient and control cells. Ex-vivo differentiation assay revealed that UCP2 deficient c-kit+ progenitor cells expansion was overall reduced by 14% with population analysis determining that the main effect is at the R3 stage. No increased rate of apoptosis was found indicating that expansion rather than cell death is being compromised. Reduced expansion of c-kit+ cells was accompanied by 30% reduction in the phosphorylated form of ERK, a ROS dependent cytosolic regulator of cell proliferation. Analysis of ROS in UCP2 null erythroid progenitors revealed altered distribution of ROS resulting in 14% decrease in cytosolic and 32% increase in mitochondrial ROS. Restoration of the cytosolic oxidative state of erythroid progenitor cells by the pro-oxidant Paraquat reversed the effect of UCP2 deficiency on cell proliferation in in vitro differentiation assays. Together, these results indicate that UCP2 is a regulator of erythropoiesis and suggests that inhibition of UCP2 function may contribute to the development of anemia.

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Real-Time Analysis of Endogenous Wnt Signalling in 3D Mesenchymal Stromal Cells

Stem Cells International ◽

10.1155/2016/7132529 ◽

2016 ◽

Vol 2016 ◽

pp. 1-9 ◽

Cited By ~ 1

Author(s):

Fatima Saleh ◽

Alice Carstairs ◽

S. Leah Etheridge ◽

Paul Genever

Keyword(s):

Time Course ◽

Molecular Mechanisms ◽

Adipogenic Differentiation ◽

Wnt Signalling ◽

Egfp Expression ◽

Culture Techniques ◽

Real Time Analysis ◽

Pathway Activation

Wnt signalling has been implicated in the regulation of stem cell self-renewal and differentiation; however, the majority of in vitro studies are carried out using monolayer 2D culture techniques. Here, we used mesenchymal stromal cell (MSC) EGFP reporter lines responsive to Wnt pathway activation in a 3D spheroid culture system to mimic better the in vivo environment. Endogenous Wnt signalling was then investigated under basal conditions and when MSCs were induced to undergo osteogenic and adipogenic differentiation. Interestingly, endogenous Wnt signalling was only active during 3D differentiation whereas 2D cultures showed no EGFP expression throughout an extended differentiation time-course. Furthermore, exogenous Wnt signalling in 3D adipogenic conditions inhibited differentiation compared to unstimulated controls. In addition, suppressing Wnt signalling by Dkk-1 restored and facilitated adipogenic differentiation in MSC spheroids. Our findings indicate that endogenous Wnt signalling is active and can be tracked in 3D MSC cultures where it may act as a molecular switch in adipogenesis. The identification of the signalling pathways that regulate MSCs in a 3D in vivo-like environment will advance our understanding of the molecular mechanisms that control MSC fate.

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A comprehensive protein–protein interactome for yeast PAS kinase 1 reveals direct inhibition of respiration through the phosphorylation of Cbf1

Molecular Biology of the Cell ◽

10.1091/mbc.e13-10-0631 ◽

2014 ◽

Vol 25 (14) ◽

pp. 2199-2215 ◽

Cited By ~ 10

Author(s):

Desiree DeMille ◽

Benjamin T. Bikman ◽

Andrew D. Mathis ◽

John T. Prince ◽

Jordan T. Mackay ◽

...

Keyword(s):

Glucose Homeostasis ◽

Protein Modification ◽

Molecular Mechanisms ◽

Binding Partners ◽

Pas Kinase ◽

Protein Interactome ◽

Deficient Mice

Per-Arnt-Sim (PAS) kinase is a sensory protein kinase required for glucose homeostasis in yeast, mice, and humans, yet little is known about the molecular mechanisms of its function. Using both yeast two-hybrid and copurification approaches, we identified the protein–protein interactome for yeast PAS kinase 1 (Psk1), revealing 93 novel putative protein binding partners. Several of the Psk1 binding partners expand the role of PAS kinase in glucose homeostasis, including new pathways involved in mitochondrial metabolism. In addition, the interactome suggests novel roles for PAS kinase in cell growth (gene/protein expression, replication/cell division, and protein modification and degradation), vacuole function, and stress tolerance. In vitro kinase studies using a subset of 25 of these binding partners identified Mot3, Zds1, Utr1, and Cbf1 as substrates. Further evidence is provided for the in vivo phosphorylation of Cbf1 at T211/T212 and for the subsequent inhibition of respiration. This respiratory role of PAS kinase is consistent with the reported hypermetabolism of PAS kinase–deficient mice, identifying a possible molecular mechanism and solidifying the evolutionary importance of PAS kinase in the regulation of glucose homeostasis.

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Dendritic cell-derived IL-2 production is regulated by IL-15 in humans and in mice

Blood ◽

10.1182/blood-2004-03-1059 ◽

2005 ◽

Vol 105 (2) ◽

pp. 697-702 ◽

Cited By ~ 65

Author(s):

Sonia Feau ◽

Valeria Facchinetti ◽

Francesca Granucci ◽

Stefania Citterio ◽

David Jarrossay ◽

...

Keyword(s):

Dendritic Cells ◽

T Cell ◽

Molecular Mechanisms ◽

Interleukin 2 ◽

Adaptive Immune ◽

Deficient Mice ◽

Mouse System

Abstract Dendritic cells (DCs) are involved in the initiation and regulation of innate and adaptive immune responses. Several molecular mechanisms regulate these diverse DC functions, and we have previously reported that mouse dendritic cells (mDCs) can produce interleukin-2 (IL-2) in vitro and in vivo, in response to microbial activation and T-cell-mediated stimuli. This property is shared by different DC subtypes, including Langerhans cells. Here we show that, on appropriate stimulation, human DCs, both plasmacytoid and myeloid subtypes, also express IL-2. Interestingly, the production of IL-2 by myeloid DCs is induced by T-cell-mediated stimuli and depends on the presence of IL-15. The key role of this cytokine in regulating IL-2 production was also confirmed in the mouse system. In particular, we could show that DCs from IL-15-deficient mice were strongly impaired in the ability to produce IL-2 after interactions with different microbial stimuli. Our results indicate that DC-produced IL-2 is tightly coregulated with the expression of IL-15.

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Notch inhibition induces mitotically generated hair cells in mammalian cochleae via activating the Wnt pathway

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1415901112 ◽

2014 ◽

Vol 112 (1) ◽

pp. 166-171 ◽

Cited By ~ 90

Author(s):

Wenyan Li ◽

Jingfang Wu ◽

Jianming Yang ◽

Shan Sun ◽

Renjie Chai ◽

...

Keyword(s):

Progenitor Cells ◽

Lineage Tracing ◽

Supporting Cells ◽

Hearing Recovery ◽

Wnt Pathways ◽

Notch Inhibition ◽

Canonical Wnt ◽

G Protein Coupled

The activation of cochlear progenitor cells is a promising approach for hair cell (HC) regeneration and hearing recovery. The mechanisms underlying the initiation of proliferation of postnatal cochlear progenitor cells and their transdifferentiation to HCs remain to be determined. We show that Notch inhibition initiates proliferation of supporting cells (SCs) and mitotic regeneration of HCs in neonatal mouse cochlea in vivo and in vitro. Through lineage tracing, we identify that a majority of the proliferating SCs and mitotic-generated HCs induced by Notch inhibition are derived from the Wnt-responsive leucine-rich repeat-containing G protein-coupled receptor 5 (Lgr5+) progenitor cells. We demonstrate that Notch inhibition removes the brakes on the canonical Wnt signaling and promotes Lgr5+ progenitor cells to mitotically generate new HCs. Our study reveals a new function of Notch signaling in limiting proliferation and regeneration potential of postnatal cochlear progenitor cells, and provides a new route to regenerate HCs from progenitor cells by interrupting the interaction between the Notch and Wnt pathways.

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Host factors that impact the biodistribution and persistence of multipotent adult progenitor cells

Blood ◽

10.1182/blood-2005-08-3289 ◽

2006 ◽

Vol 107 (10) ◽

pp. 4182-4188 ◽

Cited By ~ 54

Author(s):

Jakub Tolar ◽

Matthew J. O'Shaughnessy ◽

Angela Panoskaltsis-Mortari ◽

Ron T. McElmurry ◽

Scott Bell ◽

...

Keyword(s):

B Cell ◽

Progenitor Cells ◽

Nk Cell ◽

Immunohistochemical Analysis ◽

Differentiation Potential ◽

Multipotent Adult Progenitor Cells ◽

Deficient Mice

Multipotent adult progenitor cells (MAPCs) are marrow-derived pluripotent stem cells with a broad differentiation potential. We sought to identify factors that affect adoptively transferred MAPCs. In vitro, MAPCs expressed low levels of major histocompatibility complex (MHC) antigens, failed to stimulate CD4+ and CD8+ T-cell alloresponses, and were targets of NK cytolysis. To study in vivo biodistribution, we labeled MAPCs with luciferase for sequential quantification of bioluminescence and DsRed2 for immunohistochemical analysis. C57BL /6 MAPCs were infused intravenously into C57BL /6, Rag-2–/– (T- and B-cell–deficient), and Rag-2–/–/IL-2Rγc–/– (T-, B-, and NK-cell–deficient) mice. In C57BL /6 mice, MAPCs were transiently detected only in the chest compared with long-term persistence in T- and B-cell–deficient mice. NK depletion reduced MAPC elimination. Because the lungs were the major uptake site after intravenous injection, intra-arterial injections were tested and found to result in more widespread biodistribution. Widespread MAPC biodistribution and long-term persistence were seen in irradiated recipients given allogeneic marrow and MAPCs; such MAPCs expressed MHC class I antigens in tissues. Our data indicate that the biodistribution and persistence of reporter gene–labeled MAPCs are maximized after intra-arterial delivery or host irradiation and that T cells, B cells, and NK cells contribute to in vivo MAPC rejection.

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PI4K2β constrains non-canonical Wnt-PCP signalling and is localised by PAR-1 (MARK2/3) phosphorylation

10.1101/660431 ◽

2019 ◽

Author(s):

S. M. Tsang ◽

William Cheng ◽

Jingjing Li ◽

Jeremy B. A. Green

Keyword(s):

Planar Cell Polarity ◽

Phosphorylation Site ◽

Phosphatidyl Inositol ◽

Embryonic Cell ◽

Wnt Signalling ◽

Reporter Assays ◽

Canonical Wnt ◽

Type Specification

ABSTRACTCanonical Wnt signalling is critically important in embryonic cell-type specification and cancer, while non-canonical Wnt signalling is primarily implicated in physical morphogenesis, especially planar cell polarity (PCP). Both are modulated by the polarity kinase PAR-1 (MARK2/3). PAR-1 phosphorylates the Wnt transducer Dishevelled, but there is evidence that it exerts control through other targets. Here we describe an in vitro screen for new targets of PAR-1 in which we identified phosphatidyl-inositol-4-kinase-2-beta (PI4K2β) as a substrate. Perturbation phenotypes and reporter assays in vivo show that PI4K2β inhibits both canonical and non-canonical Wnt pathways, in contrast to PI4K2α, which promotes canonical but does not affect non-canonical signalling. We show that PI4K2β acts in Wnt-responding tissue, not in Wnt production or secretion. Subcellularly, PI4K2β is cortically enriched, unlike PI4K2α, and is basolateral in polarised cells. Mutation of the PAR-1 phosphorylation site of PI4K2β mis-localises it and the endogenous core PCP protein, Vangl2. Our results reveal that PAR-1 interacts with the vertebrate PCP signalling pathway via PI4K2β.

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Phosphatase Wip1 negatively regulates neutrophil development through p38 MAPK-STAT1

Blood ◽

10.1182/blood-2012-05-432674 ◽

2013 ◽

Vol 121 (3) ◽

pp. 519-529 ◽

Cited By ~ 55

Author(s):

Guangwei Liu ◽

Xuelian Hu ◽

Bo Sun ◽

Tao Yang ◽

Jianfeng Shi ◽

...

Keyword(s):

P38 Mapk ◽

Molecular Mechanisms ◽

Negative Regulator ◽

Cell Type ◽

A Cell ◽

Cell Type Specific ◽

Neutrophil Differentiation ◽

Deficient Mice

Abstract Neutrophils are critically involved in host defense and tissue damage. Intrinsic molecular mechanisms controlling neutrophil differentiation and activities are poorly defined. Herein we found that p53-induced phosphatase 1(Wip1) is preferentially expressed in neutrophils among immune cells. The Wip1 expression is gradually up-regulated during the differentiation of myeloid precursors into mature neutrophils. Wip1-deficient mice and chimera mice with Wip1−/− hematopoietic cells had an expanded pool of neutrophils with hypermature phenotypes in the periphery. The in vivo and in vitro studies showed that Wip1 deficiency mainly impaired the developing process of myeloid progenitors to neutrophils in an intrinsic manner. Mechanism studies showed that the enhanced development and maturation of neutrophils caused by Wip1 deficiency were mediated by p38 MAPK-STAT1 but not p53-dependent pathways. Thus, our findings identify a previously unrecognized p53-independent function of Wip1 as a cell type-specific negative regulator of neutrophil generation and homeostasis through limiting the p38 MAPK-STAT1 pathway.

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A cutting-edge approach unravels a novel role for CDK6 in leukemic progenitor cells

10.1101/2020.10.05.325886 ◽

2020 ◽

Author(s):

Eszter Doma ◽

Isabella Maria Mayer ◽

Tania Brandstoetter ◽

Barbara Maurer ◽

Reinhard Grausenburger ◽

...

Keyword(s):

Progenitor Cells ◽

Cell Lines ◽

Progenitor Cell ◽

Molecular Mechanisms ◽

List Type ◽

Robust Method ◽

Cell Homing ◽

Key Points

AbstractStudies of molecular mechanisms of hematopoiesis and leukemogenesis are hampered by the unavailability of progenitor cell lines that accurately mimic the situation in vivo. We now report a robust method to generate and maintain LSK (lin-, Sca-1+, c-Kit+) cells which closely resemble MPP1 cells. HPCLSK reconstitute hematopoiesis in lethally irradiated recipient mice over more than eight months. Upon transformation with different oncogenes including BCR/ABL, FLT3-ITD or MLL-AF9 their leukemic counterparts maintain stem cell properties in vitro and recapitulate leukemia formation in vivo. The method to generate HPCLSK can be applied to transgenic mice and we illustrate it for CDK6-deficient animals. Upon BCR/ABLp210 transformation, Cdk6-/- HPCLSKs induce disease with a significantly enhanced latency and reduced incidence, showing the importance of CDK6 in leukemia formation. Studies of the CDK6 transcriptome in murine HPCLSK and human BCR/ABL+ cells have verified that certain pathways depend on CDK6 and have uncovered a novel CDK6-dependent signature, suggesting a role for CDK6 in leukemic progenitor cell homing. Loss of CDK6 may thus lead to a defect in homing. The HPCLSK system represents a unique tool for combined in vitro and in vivo studies and enables the production of large quantities of genetically modifiable hematopoietic or leukemic stem/progenitor cells.Key pointsWe describe the generation of murine cell lines (HPCLSK) which reliably mimic hematopoietic/leukemic progenitor cells.Cdk6-/- BCR/ABLp210 HPCLSKs uncover a novel role for CDK6 in homing.

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