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This report details the establishment of a transgenic goat model in order to produce human lactoferrin (hLf) in the mammary gland for large-scale application and research. Two transgenic male goats were generated by microinjecting sequence encoding hLf cDNA to the pronuclear. In the two lines, derived from the two founders, eight lactating female goats could secrete recombinant human lactoferrin (rhLf) at concentrations of up to 0.765 mg/ml. The method of purifying the rhLf from the milk was achieved using ion-exchange chromatography and resulted in 97% purity. Biochemical and physicochemical characteristics of rhLf were similar to native lactoferrin (nhLf); this included N-terminal sequence, isoelectric point, molecular mass, glycosylation, iron-binding/releasing ability, thermal stability, and proteolysis. The rhLf showed broad spectrum antibacterial activity inhibiting the growth of several pathogenic bacterial strains. Also investigated, although to a lesser degree, was a practicable pasteurization method for the downstream processing of rhLf and, further, a method for the oral administration of rhLf. On the basis of these results, our studies show an optimistic and promising approach for the large-scale production and therapeutic application of rhLf expressed in transgenic goats.

Preosteoblasts are precursor cells that are committed to the osteoblast lineage. Differentiation of these cells to mature osteoblasts is regulated by the extracellular factors and environmental cues. Recent studies have implicated mTOR signaling in the regulation of osteoblast differentiation. However, mTOR exists in two distinct protein complexes (mTORC1 and mTORC2), and the specific role of mTORC1 in regulating the progression of preosteoblasts to mature osteoblastis still unclear. In this study, we first deleted Raptor, a unique and essential component of mTORC1, in primary calvarial cells. Deletion of Raptor resulted in loss of mTORC1 but an increase in mTORC2 signaling without overtly affecting autophagy. Under the osteogenic culture condition, Raptor-deficient cells exhibited a decrease in matrix synthesis and mineralization. qPCR analyses revealed that deletion of Raptor reduced the expression of late-stage markers for osteoblast differentiation (Bglap, Ibsp, and Col1a), while slightly increasing early osteoblast markers (Runx2, Sp7, and Alpl). Consistent with the findings in vitro, genetic ablation of Raptor in osterix-expressing cells led to osteopenia in mice. Together, our findings have identified a specific role for mTORC1 in the transition from preosteoblasts to mature osteoblasts.

Hedgehog (Hh) signaling is essential for osteoblast differentiation in the endochondral skeleton during embryogenesis. However, the molecular mechanism underlying the osteoblastogenic role of Hh is not completely understood. Here, we report that Hh markedly induces the expression of insulin-like growth factor 2 (Igf2) that activates the mTORC2-Akt signaling cascade during osteoblast differentiation. Igf2-Akt signaling, in turn, stabilizes full-length Gli2 through Serine 230, thus enhancing the output of transcriptional activation by Hh. Importantly, genetic deletion of the Igf signaling receptor Igf1r specifically in Hh-responding cells diminishes bone formation in the mouse embryo. Thus, Hh engages Igf signaling in a positive feedback mechanism to activate the osteogenic program.

Poor development of the interspecies somatic cell nuclear transfer (iSCNT) embryos was due to nuclear-mitochondrial incompatibility. In humans, it has been known that ooplast transfer (OT) could support normal fertilization, the development of embryos and prevents the transmission of mtDNA disease. To investigate whether OT could support development of the iSCNT embryos, the ooplast of Triploid Pronucleus (3PN) zygote which would be discarded in IVF lab was transferred into the enucleated goat oocytes to construct humanized iSCNT embryos in our study. The results showed the 3PN-OT could significantly improve the early development of humanized iSCNT embryos. The percentage of blastocyst development of OT group was also higher than that of the control group. Interestingly, the morphology of some OT-iSCNT blastocysts was similar to normal human blastocysts in vitro fertilization, while the morphology of iSCNT blastocysts from control group was similar to goat blastocysts. Importantly, the pluripotent marker Oct4 of the OT-iSCNT blastocyst was expressed stronger than that of the control group. These results suggested that 3PN-OT could improve the developmental potency of human iSCNT embryos and would facilitate establishing ESCs from iSCNT blastocysts.

Mammalian target of rapamycin (mTOR) is an evolutionarily conserved serine/threonine kinase controlling many physiological processes in mammals. mTOR functions in two distinct protein complexes, namely mTORC1 and mTORC2. Compared to mTORC1, the specific roles of mTORC2 are less well understood. To investigate the potential contribution of mTORC2 to skeletal development and homeostasis, we have genetically deleted Rictor, an essential component of mTORC2, in the limb skeletogenic mesenchyme of the mouse embryo. Loss of Rictor leads to shorter and narrower skeletal elements in both embryos and postnatal mice. In the embryo, Rictor deletion reduces the width but not the length of the initial cartilage anlage. Subsequently, the embryonic skeletal elements are shortened due to a delay in chondrocyte hypertrophy, with no change in proliferation, apoptosis, cell size, or matrix production. Postnatally, Rictor-deficient mice exhibit impaired bone formation, resulting in thinner cortical bone, but the trabecular bone mass is relatively normal thanks to a concurrent decrease in bone resorption. Moreover, Rictor-deficient bones exhibit a lesser anabolic response to mechanical loading. Thus, mTORC2 signaling is necessary for optimal skeletal growth and bone anabolism.

In producing transgenic livestock, selectable marker genes (SMGs) are usually used to screen transgenic cells from numerous normal cells. That results in SMGs integrating into the genome and transmitting to offspring. In fact, SMGs could dramatically affect gene regulation at integration sites and also make the safety evaluation of transgenic animals complicated. In order to determine the deletion time and methods in the process of producing transgenic goats, the feasibility of deleting SMGs was explored by Cre/LoxP before or after somatic cell cloning. In addition, we compared the efficiency of protein transduction with plasmids co-transduction. We could delete 43.9% SMGs after screening out the transgenic cell clones, but these cells could not be applied to somatic cells cloning because of serious aging after two gene modifications. The SMG-free cells suitable for nuclear transfer were accessible by using the cells of transgenic goats, but this approach was more time consuming. Finally, we found that the Cre plasmid could delete SMGs with an efficiency of 7.81%, but about 30% in SMG-free cells had sequences of Cre plasmid. Compared with Cre plasmid, the integration of new exogenous gene could be avoided by TAT-CRE protein transduction, and the deletion rate of TAT-CRE transduction was between 43.9 and 72.8%. Therefore, TAT-Cre transduction could be an effective method for deleting selectable marker genes.

WNT signaling has been implicated in both embryonic and postnatal bone formation. However, the pertinent WNT ligands and their downstream signaling mechanisms are not well understood. To investigate the osteogenic capacity of WNT7B and WNT5A, both normally expressed in the developing bone, we engineered mouse strains to express either protein in a Cre-dependent manner. Targeted induction of WNT7B, but not WNT5A, in the osteoblast lineage dramatically enhanced bone mass due to increased osteoblast number and activity; this phenotype began in the late-stage embryo and intensified postnatally. Similarly, postnatal induction of WNT7B in Runx2-lineage cells greatly stimulated bone formation. WNT7B activated mTORC1 through PI3K-AKT signaling. Genetic disruption of mTORC1 signaling by deleting Raptor in the osteoblast lineage alleviated the WNT7B-induced high-bone-mass phenotype. Thus, WNT7B promotes bone formation in part through mTORC1 activation., Author Summary The human bone tissue is of considerable regenerative capacity as reflected in bone remodeling and in fracture healing. However, bone tissue regeneration deteriorates with age, and tremendous unmet medical needs exist for safe and effective strategies to stimulate bone formation in older individuals commonly inflicted with osteoporosis or osteopenia. WNT signaling has emerged as a promising target pathway for developing novel bone anabolic therapeutics. Identifying bone-promoting WNT ligands and elucidating the underlying mechanisms may lead to useful therapeutic targets. The present study reports that WNT7B potently enhances bone formation through activation of mTORC1 in the mouse.

Mammalian cloning has been one of the most active research topics in the world. Cloning within vitro culured foetal fibroblast cells, in comparison with embryonic cells, can be used not only to theoretically study the embryonic or cellular development and differentiation in mammals, but also to utilize the unlimited fibroblast cells to produce large numbers of clonings. The preliminary results are as follows: (i) The division and development of the cloned embryos with embryonic donor cells and goat foetal fibroblast donor cells were 55%, 77% and 35%, 31%, respectively. There is no significant statistical difference between them, (ii) These studies result in the birth of two cloned goats derived from two 30-day foetal fibroblast cell lines, which are the first cloned mammals from somatic cells in China. This project has established a technological data base for the furture research on adult mammalian somatic cloning and nucleocytoplasmic interactions in animal development, and a novel technique for the cloning of animals with a high-level expression of transgene(s).

The present work has generated transgenic mice with a hybrid gene construct consisting of genomic sequences encodinghuman erythropoietin (hEPO) and governed by regulatory sequences of mousewhey acidic protein (mWAP). The construct proved effective by transient expression in lactating animal. After introducing hybrid gene construct into single-cell embryo via pronuclear microinjection, surviving embryo are reimplanted into pseudopregnant foster mother mouse. 58 mice of 86 generation zero mice obtained were identified to be positive by PCR-Southern blot and genomic DNA Southern blot methods. The integration rate is 67%.hEPO was expressed in the milk of 16 mice of 39 mice measured byhEPO ELISA kit The expression level gets over 15 μg/mL.

AEDock based on AutoDock2.4 is developed with annealing evolution algorithm (AEA) in place of simulated annealing algorithm (SA) for supermolecular conformation searching. Because AEA takes advantage of both the genetic algorithm (GA) and the simulated annealing algorithm, the results of AEDock show that AEA can predict the binding conformations of ligands with up to 10 rotatable bonds to a rigid macromolecular target. The case of 1 hvr is only one of six cases where SA in AutoDock 2.4 failed to find an energy less than that of the crystal. It is used here to compare the performance of SA with AEA. The results of comparison show that fewer states are needed in AEA than in SA, but the success rate of AEA is much higher.

Advanced prostate cancer is characterized by incurable castration-resistant progression and osteoblastic bone metastasis. While androgen deprivation therapy remains the primary treatment for advanced prostate cancer, resistance inevitably develops. Importantly, mounting evidence indicates that androgen receptor (AR) signaling continues to play a critical role in the growth of advanced prostate cancer despite androgen deprivation. While the mechanisms of aberrant AR activation in advanced prostate cancer have been extensively studied, the downstream AR target genes involved in the progression of castration resistance are largely unknown. Here, we identify WNT7B as a direct AR target gene highly expressed in castration-resistant prostate cancer (CRPC) cells. Our results show that expression of WNT7B is necessary for the growth of prostate cancer cells and that this effect is enhanced under androgen-deprived conditions. Further analyses reveal that WNT7B promotes androgen-independent growth of CRPC cells likely through the activation of protein kinase C isozymes. Our results also show that prostate cancer-produced WNT7B induces osteoblast differentiation in vitro through a direct cell–cell interaction, and that WNT7B is upregulated in human prostate cancer xenografts that cause an osteoblastic reaction when grown in bone. Taken together, these results suggest that AR-regulated WNT7B signaling is critical for the growth of CRPC and development of the osteoblastic bone response characteristic of advanced prostate cancer. Mol Cancer Res; 11(5); 482–93. ©2013 AACR.

Somatic cell-mediated transgenesis is routinely used to transfer exogenous genes to livestock genomes. However, transgene insertion events are essentially random which may lead to transgene silencing or alter animal phenotype because of insertional mutagenesis. To overcome these problems, we established a gene manipulation system in goat somatic cells based on homologous recombination and flp recombinase-mediated site-specific integration. First, we performed gene targeting to introduce an frt-docking site into the α1 (I) procollagen (ColA1) locus in goat somatic cells. Second, the targeted cell clones were rejuvenated by embryo cloning, and the vigorous cells with targeted frt were reestablished. Third, a gene-replacement system was used to introduce an EGFP reporter gene into the targeted ColA1 locus via flp mediated recombination. As a result, the transgenic somatic cell exhibited faithful expression of EGFP gene under control of the CMV promoter. Similarly, other expression vectors can be introduced into the defined site to evaluate gene functions or express valuable proteins. The gene manipulation system described here will be applicable in other livestock somatic cells, and would allow for the rapid generation of livestock with transgene targeted to the defined site.

Notch signaling between neighboring cells controls many cell fate decisions in metazoans both during embryogenesis and in postnatal life. Previously, we uncovered a critical role for physiological Notch signaling in suppressing osteoblast differentiation in vivo. However, the contribution of individual Notch receptors and the downstream signaling mechanism have not been elucidated. Here we report that removal of Notch2, but not Notch1, from the embryonic limb mesenchyme markedly increased trabecular bone mass in adolescent mice. Deletion of the transcription factor RBPjk, a mediator of all canonical Notch signaling, in the mesenchymal progenitors but not the more mature osteoblast-lineage cells, caused a dramatic high-bone-mass phenotype characterized by increased osteoblast numbers, diminished bone marrow mesenchymal progenitor pool, and rapid age-dependent bone loss. Moreover, mice deficient in Hey1 and HeyL, two target genes of Notch-RBPjk signaling, exhibited high bone mass. Interestingly, Hey1 bound to and suppressed the NFATc1 promoter, and RBPjk deletion increased NFATc1 expression in bone. Finally, pharmacological inhibition of NFAT alleviated the high-bone-mass phenotype caused by RBPjk deletion. Thus, Notch-RBPjk signaling functions in part through Hey1-mediated inhibition of NFATc1 to suppress osteoblastogenesis, contributing to bone homeostasis in vivo., Author Summary Osteoporosis is a disease caused by disruption of the balance between bone formation and resorption resulting in a net loss of bone mass. Although anti-resorptive agents are the current mainstay of osteoporosis therapy, novel strategies to promote bone formation are critically needed for more effective prevention and treatment of the disease. Notch signaling, an evolutionally conserved mechanism among multi-cellular organisms, was recently shown to control bone formation and therefore represents a potential target pathway for novel bone-promoting therapeutics. In this study we elucidate the intracellular signaling mechanism through which Notch controls bone formation, providing a molecular framework that may guide future drug development.

In the application of therapeutic antibodies, large molecular weight of antibodies is always a problem that prevents them from penetrating into tissues or binding to antigenic determinants. To overcome this problem, we investigated the function of the heavy chain variable domain of a monoclonal anti-VEGF human IgM antibody derived from the Five-Feature Translocus Mice. We cloned the cDNA of the heavy chain variable domain, which was then inserted into pET28a vector and expressed in Escherichia coli. After purification and renaturation of the denatured recombinant protein, we obtained a 16 kDa antibody fragment, which is named as rhVVH. By immunoassaying its VEGF-binding capability in vitro, we proved that rhVVH retains this activity as the complete IgM. Importantly, rhVVH is shown to inhibit the HUVEC cell proliferation in a concentration-dependent manner. Our results indicate that the single heavy chain variable domain might inherit part of the biological function of the complete IgM antibody, which provided a valuable potential in further research on antibody miniaturisation.

Interleukin-21 is a type I cytokine mainly produced by activated CD4+ T cells that acts as a regulator of immune system. In this work, hIL-21cDNA was amplified from human peripheral blood lymphocytes by RT-PCR, and then inserted into pPIC9K. The recombinant vector pPIC9K-hIL21cDNA was linearized by Sac I, and transformed into Pichia pastoris strain GS115 by electroporation. Transformants were selected by G418 and confirmed by PCR. The recombinant protein was expressed and secreted into the supernatant after inducing by methanol. SDS-PAGE analysis indicated the molecular weight of rhIL-21 was about 16 kD. ELISA results show that the yield of rhIL-21 reach 229.28 mg/L, rhIL-21 was purified from culture supernatants, and it was purified to about 95% purity with ion-exchange chromatography. When co-stimulate with Con A, rhIL-21 can promote the proliferation of human lymphocytes. This is the first expression of bio-active rhIL-21 in Pichia pastoris. It lays a foundation for further research in immunotherapy and cancer therapy.

Promoter-trap strategy for enriching targeted colonies has been usually used to elevate the gene targeting efficiency in somatic cells. Knocking out Prnp in animals by gene targeting can render them resistant to Prion diseases. We constructed a bovine Prnp promoter-less targeting vector BoPrPneo, then transfected the linearized vector into the bovine fetal fibroblasts BFF through electroporation. After selecting in cell culture medium with 250 microg/mL G418, we obtained 99 drug-resistant cell colonies, 4 of them were positive for targeted events after PCR screening, and the targeted colonies were further confirmed by sequencing and Southern blotting. This suggests that one allele of Prnp has been successfully knocked out in bovine fetal fibroblasts. This research supplies a simple, safe and effective method to targeting bovine Prnp.

The preimplantation development competences of somatic cell nuclear transfer (SCNT) embryos reconstructed with enuleated goat (Capra hircus) Metaphase II (MII) oocytes matured in vivo and whole cells derived from adult fibroblasts of several mammalian species (goat, boer goat, bovine, tahr, panda) and human patient were evaluated. Results obtained from our experiments revealed that these reconstructed SCNT embryos could complete preimplantation development to form blastocysts. The fusion rate and blastocyst rate of intra-species SCNT embryos (Capra hircus as control) was 78.67 (557/708); 56.29% (264/469), that of sub-species or inter-species SCNT embryos were: boer goat 78.18% (541/692); 33.90% (40/118), bovine 70.53% (146/207); 22.52% (25/111), tahr 53.51% (61/114); 5.26% (3/570), panda 79.82% (1159/1452); 8.35% (75/898) and human 68.76% (317/461); 5.41% (16/296), respectively. It is concluded that (1) there are no relationships between fusion rate and relativeness of the recipient cytoplasm to nucleus donor cells, (2) cytoplast of the goat MII oocyte can support the preimplantation development of SCNT embryos reconstructed with nucleus from other species, (3) the blastocyst rate of close relative inter-species SCNT embryos is higher than that of distant relative inter-species SCNT embryos.

The objective of this study was to determine the effect of different frequencies of transvaginal ovum pick-up (OPU) on the quantity of recovered cumulus oocyte complexes (COCs) and subsequently the competence of matured oocytes to support the preimplantation development of cloned bovine embryos. The COCs were aspirated from the ovaries of 6 Chinese Holstein cows by transvaginal follicle aspiration twice a week (every 3 or 4 days) (Group I), every 5 days (Group II), once a week (every 7 days) (Group III), every 10 days (Group IV), and once every 2 weeks (every 14 days) (Group V). The developmental stages of the follicles were confirmed by the diameter of the dominant follicle (DF) and harvested COCs, and the dynamics of the follicular wave were clarified. In addition, extrusions of the first polar body (PB I) from the oocytes were observed at different time intervals after the initiation of in vitro maturation (IVM) to identify the appropriate culture time window for somatic cell nuclear transfer. Matured oocytes were used to produce cloned bovine embryos that were subsequently cultured in the goat oviduct. After 7 days, the embryos were flushed out, and the developmental rates of the blastocysts were compared among the five groups. The results showed that the aspirations of all follicles ≥3 mm in diameter (D1) induced and synchronized the dynamics of the follicular wave, and the subordinate follicles became atretic after 4 days (D5). Another follicular wave started between D7 and D10, and atresia in the subordinate follicles in the second follicular wave began on D14. The timing of meiotic progression (from the initiation of IVM to the extrusion of PB I) in the oocytes obtained by OPU was later than that of the oocytes obtained from the abattoir. Between 20 and 24 hr after the initiation of IVM, 20% of the oocytes extruded their PB I. Further, 80% (520/650) of the harvested COCs were arrested at metaphase II (MII) by 22 hr of the initiation of IVM and were used as cytoplast donors. The rates of development of the reconstituted embryos to the blastocyst stage were 23.1% (Group I), 15.0% (Group II), 10.9% (Group III), 4.9% (Group IV), and 29.0% (Group V). The results indicate that the developmental potential of follicles from the same living donors were different when different intervals of OPU were adopted and early atretic follicles from the second follicular wave had higher competence to support the early development of cloned bovine embryos. Mol. Reprod. Dev. 75: 1710–1715, 2008. © 2008 Wiley-Liss, Inc.

The purpose of this study was to prepare a fully human anti-VEGF (vascular endothelial growth factor) monoclonal antibody with anti-tumor activity from five-feature mice which express human immunoglobin loci. Four hybridomas secreting mAb stably were isolated successfully. Some characters such as isotypes, cross-reactivity, inhibition on the binding of hVEGF to VEGFR-2, dissociation constants and the idiotypic characteristic were determined. Proliferation of T24 and Ls-174-T cell line and nude mice bearing human colorectal cancer were used to evaluate therapeutic effects and safety of this mAb. Pharmacokinetics data shows the half life of this mAb was about 5 days after a single intravenous injection. These results suggest the fully human anti-VEGF mAb maybe safe and efficient for cancer treatment.

The Bambi (Bmp and activin membrane-bound inhibitor) gene encodes a transmembrane protein highly similar in amino acid sequence to transforming growth factor-beta (TGF-beta receptors, however, the Bambi intracellular domain is short and lacks a serine/threonine-kinase domain that is essential for transducing TGF beta signaling. Previous biochemical assays showed that Bambi interacts directly with BMP receptors and antagonizes BMP signaling. Interestingly, the expression of Bambi largely overlaps, both temporally and spatially, with that of Bmp4 during early embryonic development in Xenopus, zebrafish, and mice, which led to the hypothesis that Bambi may function to regulate BMP signaling during embryogenesis. To directly analyze the roles of Bambi during embryonic development, we generated mice carrying a conditional allele of Bambi, Bambi(flox), with loxP sequences flanking the first exon that encodes the N-terminus and signal peptide region of the Bambi protein. Mice homozygous for this targeted conditional allele appear normal and fertile. We crossed the Bambi(flox)/+ mice to the EIIa-Cre transgenic mice and generated mice carrying deletion of the first exon of the Bambi gene. Surprisingly, mice homozygous for the deleted allele were viable, fertile and did not exhibit any discernible developmental defect. Our data exclude an essential role for Bambi in mouse embryonic development and postnatal survival.

The development of genetically engineered animals has brought with it increasing concerns about biosafety issues. We therefore evaluated the risks of growth hormone from transgenic goats, including the probability of horizontal gene transfer and the impact on the microbial community of the goats' gastrointestinal tracts, feces and the surrounding soil. The results showed that neither the GH nor the neoR gene could be detected in the samples. Moreover, there was no significant change in the microbial community of the gastrointestinal tracts, feces and soil, as tested with PCR-denaturing gradient gel electrophoresis and 16S rDNA sequencing. Finally, phylogenetic analysis showed that the intestinal content, feces and soil samples all contained the same dominant group of bacteria. These results demonstrated that expression of goat growth hormone in the mammary of GH transgenic goat does not influence the microflora of the intestine, feces and surrounding soil.

The cellular prion protein (PrPC), a membrane glycoprotein anchored to the outer surface of neurons, lymphocytes and other cells, is associated directly with the pathogenesis of the transmissible spongiform encephalopathies (TSEs) occurring mainly in humans, cattle, sheep and goats. Although mice lacking PrPC develop and reproduce normally and are resistant to scrapie infection, large animals lacking PrPC, especially those species in which TSE occurs naturally, are currently not available. Here, five live PRNP +/− goats cloned by gene targeting are reported. Detailed RNA-transcription and protein-expression analysis of one PRNP +/− goat showed that one allele of the caprine PRNP gene had been disrupted functionally. No gross abnormal development or behaviour could be seen in these PRNP +/− goats up to at least 3 months of age. These heterozygous PRNP +/− goats are ready to be used in producing homozygous PRNP −/− goats in which no PrPC should be expressed.

Yeast artificial chromosomes (YACs) as transgenes in transgenic animals are likely to ensure optimal expression levels. Microinjection of YACs is the exclusive technique used to produce YACs transgenic livestock so far. However, low efficiency and high cost are its critical restrictive factors. In this study, we presented a novel procedure to produce YACs transgenic livestock as mammary gland bioreactor. A targeting vector, containing the gene of interest-a human serum albumin minigene (intron 1, 2), yeast selectable marker (G418R), and mammalian cell resistance marker (neo{sup r}), replaced the {alpha}-lactalbumin gene in a 210 kb human {alpha}-lactalbumin YAC by homogeneous recombination in yeasts. The chimeric YAC was introduced into goat fetal fibroblasts using polyethylene glycol-mediated spheroplast fusion. PCR and Southern analysis showed that intact YAC was integrated in the genome of resistant cells. Perhaps, it may offer a cell-based route by nuclear transfer to produce YACs transgenic livestock.

To investigate the leukemogenic potential of PML-RARalpha fusion protein in vivo, hCG-PML-RARalpha transgene was constructed using molecular cloning technique and hCG-PML-RARalpha transgenic mice were generated. The genotype and phenotype of hCG-PML-RARalpha transgenic mice were analyzed by PCR, RT-PCR, morphology of peripheral blood and bone marrow cells, and pathological examination of spleen, liver and bone marrow. As a result, acute promyelocytic leukemia was developed in 3 hCG-PML-RARalpha transgenic mice in 1 - 5 months. The results demonstrated that PML-RARalpha fusion protein plays a crucial role in leukemogenesis.

The central importance of BMP signaling in the development and homeostasis of synovial joint of appendicular skeleton has been well documented, but its role in the development of temporomandibular joint (TMJ), also classified as a synovial joint, remains completely unknown. In this study, we investigated the function of BMPRIA mediated signaling in TMJ development in mice by transgenic loss-of- and gain-of-function approaches. We found that BMPRIA is expressed in the cranial neural crest (CNC)-derived developing condyle and glenoid fossa, major components of TMJ, as well as the interzone mesenchymal cells. Wnt1-Cre mediated tissue specific inactivation of BmprIa in CNC lineage led to defective TMJ development, including failure of articular disc separation from a hypoplastic condyle, persistence of interzone cells, and failed formation of a functional fibrocartilage layer on the articular surface of the glenoid fossa and condyle, which could be at least partially attributed to the down-regulation of Ihh in the developing condyle and inhibition of apoptosis in the interzone. On the other hand, augmented BMPRIA signaling by Wnt1-Cre driven expression of a constitutively active form of BmprIa (caBmprIa) inhibited osteogenesis of the glenoid fossa and converted the condylar primordium from secondary cartilage to primary cartilage associated with ectopic activation of Smad-dependent pathway but inhibition of JNK pathway, leading to TMJ agenesis. Our results present unambiguous evidence for an essential role of finely tuned BMPRIA mediated signaling in TMJ development.

Summary WNT signaling controls many biological processes including cell differentiation in metazoans. However, how WNT reprograms cell identity is not well understood. We have investigated the potential role of cellular metabolism in WNT-induced osteoblast differentiation. WNT3A induces aerobic glycolysis known as Warburg effect by increasing the level of key glycolytic enzymes. The metabolic regulation requires LRP5 but not β-catenin and is mediated by mTORC2-AKT signaling downstream of RAC1. Suppressing WNT3A-induced metabolic enzymes impairs osteoblast differentiation in vitro. Deletion of Lrp5 in the mouse, which decreases postnatal bone mass, reduces mTORC2 activity and glycolytic enzymes in bone cells and lowers serum lactate levels. Conversely, mice expressing a mutant Lrp5 that causes high bone mass exhibit increased glycolysis in bone. Thus, WNT-LRP5 signaling promotes bone formation in part through direct reprogramming of glucose metabolism. Moreover, regulation of cellular metabolism may represent a general mechanism contributing to the wide-ranging functions of WNT proteins.

Loss of NOTCH signaling in postnatal murine joints results in osteoarthritis, indicating a requirement for NOTCH during maintenance of joint cartilage. However, NOTCH signaling components are substantially increased in abundance in posttraumatic osteoarthritis in humans and mice, suggesting either a reparative or a pathological role for NOTCH activation in osteoarthritis. We investigated a potential dual role for NOTCH in joint maintenance and osteoarthritis by generating two mouse models overexpressing the NOTCH1 intracellular domain (NICD) within postnatal joint cartilage. The first mouse model exhibited sustained NOTCH activation to resemble pathological NOTCH signaling, whereas the second model had transient NOTCH activation, which more closely reflected physiological NOTCH signaling. Sustained NOTCH signaling in joint cartilage led to an early and progressive osteoarthritic-like pathology, whereas transient NOTCH activation enhanced the synthesis of cartilage matrix and promoted joint maintenance under normal physiological conditions. Through RNA-sequencing, immunohistochemical, and biochemical approaches, we identified several targets that could be responsible for NOTCH-mediated cartilage degradation, fibrosis, and osteoarthritis progression. These targets included components of the interleukin-6 (IL-6)-signal transducer and activator of transcription 3 (STAT3) and mitogen-activated protein kinase signaling pathways, which may also contribute to the posttraumatic development of osteoarthritis. Together, these data suggest a dual role for the NOTCH pathway in joint cartilage, and they identify downstream effectors of NOTCH signaling as potential targets for disease-modifying osteoarthritis drugs.