Recapitulating the immune system of hemophilia A patients with inhibitors using immunodeficient mice

BACKGROUND AND AIM

Treating hemophilia A patients who develop inhibitors remains a clinical challenge. A mouse model of hemophilia A can be used to test the efficacy of strategies for inhibitor suppression, but the differences in the immune systems of mice and humans limit its utility. To address this shortcoming, we established a humanized NOD/SCID-IL2rγnull hemophilia A (hu-NSG-HA) mouse model with a severely deficient mouse immune system presenting a patient's adapted immune cells.

METHODS AND RESULTS

Through intrasplenic injection with patient inhibitor-positive peripheral blood mononuclear cells (PBMCs), utilizing an adeno-associated viral delivery system expressing human BLyS, and regular FVIII challenge, human C19+ B cells were expanded in vivo to secrete anti-FVIII antibodies. Both the inhibitor and the human anti-FVIII IgG, including the predominant subclasses (IgG1 and IgG4) present in the majority of inhibitor patients, were detected in the mouse model. We further segregated and expanded the different clones of human anti-FVIII-secreting cells through subsequent transplantation of splenocytes derived from hu-NSG-HA mice into another NSG-HA mouse. By transplanting a patient's PBMCs into the NSG-HA mouse model, we demonstrated the success of reintroducing a strong anti-FVIII immune response for a short period in mice with the immune systems of inhibitor-positive patients.

CONCLUSION

Our results demonstrate a potential tool for directly obtaining functional human-derived antigen-specific antibodies and antibody-secreting cells, which may have therapeutic value for testing patient-specific immune responses to treatment options to assist in clinical decisions.

NRICM101 ameliorates SARS-CoV-2-S1-induced pulmonary injury in K18-hACE2 mice model

The coronavirus disease 2019 (COVID-19) pandemic continues to represent a challenge for public health globally since transmission of different variants of the virus does not seem to be effectively affected by the current treatments and vaccines. During COVID-19 the outbreak in Taiwan, the patients with mild symptoms were improved after the treatment with NRICM101, a traditional Chinese medicine formula developed by our institute. Here, we investigated the effect and mechanism of action of NRICM101 on improval of COVID-19-induced pulmonary injury using S1 subunit of the SARS-CoV-2 spike protein-induced diffuse alveolar damage (DAD) of hACE2 transgenic mice. The S1 protein induced significant pulmonary injury with the hallmarks of DAD (strong exudation, interstitial and intra-alveolar edema, hyaline membranes, abnormal pneumocyte apoptosis, strong leukocyte infiltration, and cytokine production). NRICM101 effectively reduced all of these hallmarks. We then used next-generation sequencing assays to identify 193 genes that were differentially expressed in the S1+NRICM101 group. Of these, three (Ddit4, Ikbke, Tnfaip3) were significantly represented in the top 30 enriched downregulated gene ontology (GO) terms in the S1+NRICM101 group versus the S1+saline group. These terms included the innate immune response, pattern recognition receptor (PRR), and Toll-like receptor signaling pathways. We found that NRICM101 disrupted the interaction of the spike protein of various SARS-CoV-2 variants with the human ACE2 receptor. It also suppressed the expression of cytokines IL-1β, IL-6, TNF-α, MIP-1β, IP-10, and MIP-1α in alveolar macrophages activated by lipopolysaccharide. We conclude that NRICM101 effectively protects against SARS-CoV-2-S1-induced pulmonary injury via modulation of the innate immune response, pattern recognition receptor, and Toll-like receptor signaling pathways to ameliorate DAD.

Targeting spike protein-induced TLR/NET axis by COVID-19 therapeutic NRICM102 ameliorates pulmonary embolism and fibrosis

The global COVID-19 pandemic remains a critical public health threat, as existing vaccines and drugs appear insufficient to halt the rapid transmission. During an outbreak from May to August 2021 in Taiwan, patients with severe COVID-19 were administered NRICM102, which was a traditional Chinese medicine (TCM) formula developed based on its predecessor NRICM101 approved for treating mild cases. This study aimed to explore the mechanism of NRICM102 in ameliorating severe COVID-19-related embolic and fibrotic pulmonary injury. NRICM102 was found to disrupt spike protein/ACE2 interaction, 3CL protease activity, reduce activation of neutrophils, monocytes and expression of cytokines (TNF-α, IL-1β, IL-6, IL-8), chemokines (MCP-1, MIP-1, RANTES) and proinflammatory receptor (TLR4). NRICM102 also inhibited the spread of virus and progression to embolic and fibrotic pulmonary injury through reducing prothrombotic (vWF, PAI-1, NET) and fibrotic (c-Kit, SCF) factors, and reducing alveolar type I (AT1) and type II (AT2) cell apoptosis. NRICM102 may exhibit its protective capability via regulation of TLRs, JAK/STAT, PI3K/AKT, and NET signaling pathways. The study demonstrates the ability of NRICM102 to ameliorate severe COVID-19-related embolic and fibrotic pulmonary injury in vitro and in vivo and elucidates the underlying mechanisms.

CD248 regulates Wnt signaling in pericytes to promote angiogenesis and tumor growth in lung cancer

The tumor microenvironment plays a central role in cancer initiation and progression. CD248 is expressed in tumor-associated stromal cells, particularly fibroblasts and pericytes. Exploring the function of CD248 has the potential to provide biological insights into tumor-supportive stroma and potential therapeutic targets. Here, we investigated the role of stromal CD248 in lung cancer. In orthotopic lung cancer transplantation models, tumor volume, density of vessels and pericytes, and functionality of tumor vessels were all lower in mice lacking Cd248 (Cd248LacZ/LacZ) compared to Cd248 wild-type or haploinsufficient mice. Two angiogenic factors, OPN and SERPINE1, were decreased in Cd248LacZ/LacZ pericytes, and supplementation with both factors rescued their proliferation and endothelial cell tube formation-promoting ability. Mechanistically, Wnt/β-catenin signaling induced Opn and Serpine1 expression and was suppressed in Cd248LacZ/LacZ pericytes. CD248 interacted with Wnt pathway repressors IGFBP4 and LGALS3BP, leading to increased Wnt/β-catenin signaling. Correspondingly, administration of a β-catenin inhibitor in Cd248+/LacZ mice mimicked the effect of Cd248 loss and blocked the growth of transplanted lung tumor cells that were resistant to this inhibitor in vitro. In addition, CD248+ pericytes co-expressed OPN and SERPINE1 and correlated with increased tumor size in human lung cancer. Additionally, high expression of CD248, OPN, and SERPINE1 associated with poor survival in lung cancer patients. In summary, CD248 de-represses Wnt signaling and upregulates OPN and SERPINE1 in pericytes, resulting in enhanced angiogenesis and lung cancer growth. This novel axis of CD248-Wnt signaling-angiogenic factors in pericytes provides a potential target for lung cancer therapy.

Insights into phenotypic differences between humans and mice with p.T721M and other C-terminal variants of the SLC26A4 gene

Recessive variants of the SLC26A4 gene are an important cause of hereditary hearing impairment. Several transgenic mice with different Slc26a4 variants have been generated. However, none have recapitulated the auditory phenotypes in humans. Of the SLC26A4 variants identified thus far, the p.T721M variant is of interest, as it appears to confer a more severe pathogenicity than most of the other missense variants, but milder pathogenicity than non-sense and frameshift variants. Using a genotype-driven approach, we established a knock-in mouse model homozygous for p.T721M. To verify the pathogenicity of p.T721M, we generated mice with compound heterozygous variants by intercrossing Slc26a4^+/T721M mice with Slc26a4^{919-2A>G/919-2A>G} mice, which segregated the c.919-2A > G variant with abolished Slc26a4 function. We then performed serial audiological assessments, vestibular evaluations, and inner ear morphological studies. Surprisingly, both Slc26a4^T721M/T721M and Slc26a4^{919-2A>G/T721M} showed normal audiovestibular functions and inner ear morphology, indicating that p.T721M is non-pathogenic in mice and a single p.T721M allele is sufficient to maintain normal inner ear physiology. The evidence together with previous reports on mouse models with Slc26a4 p.C565Y and p.H723R variants, support our speculation that the absence of audiovestibular phenotypes in these mouse models could be attributed to different protein structures at the C-terminus of human and mouse pendrin.

Impairment in renal medulla development underlies salt wasting in Clc-k2 channel deficiency

The prevailing view is that the ClC-Ka chloride channel (mouse Clc-k1) functions in the thin ascending limb to control urine concentration, whereas the ClC-Kb channel (mouse Clc-k2) functions in the thick ascending limb (TAL) to control salt reabsorption. Mutations of ClC-Kb cause classic Bartter syndrome, characterized by renal salt wasting, with perinatal to adolescent onset. We studied the roles of Clc-k channels in perinatal mouse kidneys using constitutive or inducible kidney-specific gene ablation and 2D and advanced 3D imaging of optically cleared kidneys. We show that Clc-k1 and Clc-k2 were broadly expressed and colocalized in perinatal kidneys. Deletion of Clc-k1 and Clc-k2 revealed that both participated in NKCC2- and NCC-mediated NaCl reabsorption in neonatal kidneys. Embryonic deletion of Clc-k2 caused tubular injury and impaired renal medulla and TAL development. Inducible deletion of Clc-k2 beginning after medulla maturation produced mild salt wasting resulting from reduced NCC activity. Thus, both Clc-k1 and Clc-k2 contributed to salt reabsorption in TAL and distal convoluted tubule (DCT) in neonates, potentially explaining the less-severe phenotypes in classic Bartter syndrome. As opposed to the current understanding that salt wasting in adult patients with Bartter syndrome is due to Clc-k2 deficiency in adult TAL, our results suggest that it originates mainly from defects occurring in the medulla and TAL during development.

A Preconditioning Strategy to Augment Retention and Engraftment Rate of Donor Cells During Hepatocyte Transplantation

BACKGROUND

Hepatocyte transplantation has been extensively investigated as an alternative to orthotopic liver transplantation. However, its application in routine clinical practice has been restricted because of low initial engraftment and subsequent repopulation.

METHODS

Using mice as a model, we have developed a minimally invasive and nontoxic preconditioning strategy based on preadministration of antibodies against hepsin to increase donor hepatocyte retention and engraftment rate.

RESULTS

Liver sinusoid diameters decreased significantly with antihepsin pretreatment, and graft cell numbers increased nearly 2-fold in the recipients' liver parenchyma for 20 days after hepatocyte transplantation. Postoperative complications such as hepatic ischemia injury or apparent immune cell accumulation were not observed in recipients. In a hemophilia B mouse model, antihepsin preconditioning enhanced the expression and clotting activity of coagulation factor IX (FIX) to nearly 2-fold that of immunoglobulin G-treated controls and maintained higher plasma FIX clotting activity relative to the prophylactic range for 50 days after hepatocyte transplantation. Antihepsin pretreatment combined with adeno-associated virus-transduced donor hepatocytes expressing human FIX-Triple, a hyperfunctional FIX variant, resulted in plasma FIX levels similar to those associated with mild hemophilia, which protected hemophilia B mice from major bleeding episodes for 50 days after transplantation. Furthermore, antihepsin pretreatment and repeated transplantation resulted in extending the therapeutic period by 30 days relative to the immunoglobulin G control.

CONCLUSIONS

Thus, this antihepsin strategy improved the therapeutic effect of hepatocyte transplantation in mice with tremendous safety and minimal invasion. Taken together, we suggest that preconditioning with antihepsin may have clinical applications for liver cell therapy.

Toward the Pathogenicity of the SLC26A4 p.C565Y Variant Using a Genetically Driven Mouse Model

Recessive variants of the SLC26A4 gene are globally a common cause of hearing impairment. In the past, cell lines and transgenic mice were widely used to investigate the pathogenicity associated with SLC26A4 variants. However, discrepancies in pathogenicity between humans and cell lines or transgenic mice were documented for some SLC26A4 variants. For instance, the p.C565Y variant, which was reported to be pathogenic in humans, did not exhibit functional pathogenic consequences in cell lines. To address the pathogenicity of p.C565Y, we used a genotype-based approach in which we generated knock-in mice that were heterozygous (Slc26a4+/C565Y), homozygous (Slc26a4C565Y/C565Y), and compound heterozygous (Slc26a4919-2A>G/C565Y) for this variant. Subsequent phenotypic characterization revealed that mice with these genotypes demonstrated normal auditory and vestibular functions, and normal inner-ear morphology and pendrin expression. These findings indicate that the p.C565Y variant is nonpathogenic for mice, and that a single p.C565Y allele is sufficient to maintain normal inner-ear physiology in mice. Our results highlight the differences in pathogenicity associated with certain SLC26A4 variants between transgenic mice and humans, which should be considered when interpreting the results of animal studies for SLC26A4-related deafness.

Deficiency of the Tbc1d21 gene causes male infertility with morphological abnormalities of the sperm mitochondria and flagellum in mice

Approximately 2-15% of couples experience infertility, and around half of these cases are attributed to male infertility. We previously identified TBC1D21 as a sterility-related RabGAP gene derived from infertile men. However, the in vivo function of TBC1D21 in male fertility remains unclear. Here, we show that loss of Tbc1d21 in mice resulted in male infertility, characterized by defects in sperm tail structure and diminished sperm motility. The mitochondria of the sperm-tail had an abnormal irregular arrangement, abnormal diameter, and structural defects. Moreover, the axoneme structure of sperm tails was severely disturbed. Several TBC1D21 interactors were selected via proteomic analysis and functional grouping. Two of the candidate interactors, a subunit protein of translocase in the outer membrane of mitochondria (TOMM20) and an inner arm component of the sperm tail axoneme (Dynein Heavy chain 7, DNAH7), confirmed in vivo physical co-localization with TBC1D21. In addition, TOMM20 and DNAH7 detached and dispersed outside the axoneme in Tbc1d21-deficient sperm, instead of aligning with the axoneme. From a clinical perspective, the transcript levels of TBC1D21 in sperm from teratozoospermia cases were significantly reduced when compared with those in normozoospermia. We concluded that TBC1D21 is critical for mitochondrial and axoneme development of mammalian sperm.

Activation of Aryl Hydrocarbon Receptor by Kynurenine Impairs Progression and Metastasis of Neuroblastoma

Neuroblastoma is the most common malignant disease of infancy, and amplification of the MYCN oncogene is closely associated with poor prognosis. Recently, expression of MYCN was shown to be inversely correlated with aryl hydrocarbon receptor (AHR) expression in neuroblastoma, and overexpression of AHR downregulated MYCN expression, promoting cell differentiation. Therefore, we further investigated the potential of AHR to serve as a prognostic indicator or a therapeutic target in neuroblastoma. First, the clinical significance of AHR in neuroblastoma was examined. Positive AHR immunostaining strongly correlated with differentiated histology of neuroblastoma and predicted better survival for patients. The mouse xenograft model showed that overexpression of AHR significantly suppressed neuroblastoma tumor growth. In addition, activation of AHR by the endogenous ligand kynurenine inhibited cell proliferation and promoted cell differentiation in vitro and in vivo. kynurenine treatment also upregulated the expression of KISS1, a tumor metastasis suppressor, and attenuated metastasis in the xenograft model. Finally, analysis of KISS1 levels in neuroblastoma patient tumors using the R2: Genomics Analysis and Visualization Platform revealed that KISS1 expression positively correlated with AHR, and high KISS1 expression predicted better survival for patients. In conclusion, our results indicate that AHR is a novel prognostic biomarker for neuroblastoma, and that overexpression or activation of AHR offers a new therapeutic possibility for patients with neuroblastoma. SIGNIFICANCE: These findings show that AHR may function as a tumor suppressor in childhood neuroblastoma, potentially influencing the aetiologic and therapeutic targeting of the disease.

Embryonic Cul4b is important for epiblast growth and location of primitive streak layer cells

Cul4b-null (Cul4bΔ/Y) mice undergo growth arrest and degeneration during the early embryonic stages and die at E9.5. The pathogenic causes of this lethality remain incompletely characterized. However, it has been hypothesized that the loss of Cul4b function in extraembryonic tissues plays a key role. In this study, we investigated possible causes of death for Cul4b-null embryos, particularly in regard to the role of embryonic Cul4b. First, we show that the loss of embryonic Cul4b affects the growth of the inner cell mass in vitro and delays epiblast development during the gastrulation period at E6.5~E7.5 in vivo, as highlighted by the absence of the epiblastic transcription factor Brachyury from E6.5~E7.5. Additionally, at E7.5, strong and laterally expanded expression of Eomes and Fgf8 signaling was detected. Sectioning of these embryos showed disorganized primitive streak layer cells. Second, we observed that Mash2-expressing cells were present in the extraembryonic tissues of Cul4b-deficient embryos at E6.5 but were absent at E7.5. In addition, the loss of Cul4b resulted in decreased expression of cyclin proteins, which are required for the cell cycle transition from G1 to S. Taken together, these observations suggest that the embryonic expression of Cul4b is important for epiblast growth during E6.5~E7.5, and the loss of Cul4b results in either delayed growth of the epiblast or defective localization of primitive streak layer cells. As a result, the signaling activity mediated by the epiblast for subsequent ectoplacental cone development is affected, with the potential to induce growth retardation and lethality in Cul4bΔ/Y embryos.

P53 ICE CRIM mouse: a tool to generate mutant allelic series in somatic cells and germ lines for cancer studies

The clustered regularly interspaced short palindromic repeat (CRISPR)/Cas9 technology facilitates somatic genome editing to reveal cooperative genetic interactions at the cellular level without extensive breeding between different mutant animals. Here we propose a transgenic inducible Cas9 effector-CRISPR mutagen ( ICE CRIM) mouse model in which CRISPR/Cas9-mediated somatic mutagenesis events can occur in response to Cre expression. The well-known tumor suppressor gene, Trp53, and 2 important DNA mismatch repair genes, Mlh1 and Msh2, were selected to be our somatic mutagenesis targets. Amplicon-based sequencing was performed to validate the editing efficiency and to identify the mutant allelic series. Crossed with various Cre lines, the Trp53 ICE CRIM alleles were activated to generate targeted cancer gene somatic or germ line mutant variants. We provide experimental evidence to show that an activated ICE CRIM can mutate both targeted alleles within a cell. Simultaneous disruption of multiple genes was also achieved when there were multiple single-guide RNA expression cassettes embedded within an activated ICE CRIM. Our mouse model can be used to generate mutant pools in vivo, which enables a functional screen to be performed in situ. Our results also provide evidence to support a monoclonal origin of hematopoietic neoplasms and to indicate that DNA mismatch repair deficiency accelerates tumorigenesis in Trp53 mutant genetic background.-Fan, H.-H., Yu, I.-S., Lin, Y.-H., Wang, S.-Y., Liaw, Y.-H., Chen, P.-L., Yang, T.-L., Lin, S.-W., Chen, Y.-T. P53 ICE CRIM mouse: a tool to generate mutant allelic series in somatic cells and germ lines for cancer studies.

Genetic Elimination of Connective Tissue Growth Factor in the Forebrain Affects Subplate Neurons in the Cortex and Oligodendrocytes in the Underlying White Matter

Connective tissue growth factor (CTGF) is a secreted extracellular matrix-associated protein, which play a role in regulating various cellular functions. Although the expression of CTGF has been reported in the cortical subplate, its function is still not clear. Thus, to explore the significance of CTGF in the brain, we created a forebrain-specific Ctgf knockout (FbCtgf KO) mouse model. By crossing Ctgf^fl/fl mice with Emx1-Cre transgenic mice, in which the expression of Cre is prenatally initiated, the full length Ctgf is removed in the forebrain structures. In young adult (2–3 months old) FbCtgf KO mice, subplate markers such as Nurr1 and Cplx3 are still expressed in the cortical layer VIb; however, the density of the subplate neurons is increased. Interestingly, in these mutants, we found a reduced structural complexity in the subplate neurons. The distribution patterns of neurons and glial cells, examined by immunohistochemistry, are comparable between genotypes in the somatosensory cortex. However, increased densities of mature oligodendrocytes, but not immature ones, were noticed in the external capsule underneath the cortical layer VIb in young adult FbCtgf KO mice. The features of myelinated axons in the external capsule were then examined using electron microscopy. Unexpectedly, the thickness of the myelin sheath was reduced in middle-aged (>12 months old), but not young adult FbCtgf KO mice. Our results suggest a secretory function of the subplate neurons, through the release of CTGF, which regulates the density and dendritic branching of subplate neurons as well as the maturation and function of nearby oligodendrocytes in the white matter.

Genetic Depletion of Thromboxane A2/Thromboxane-Prostanoid Receptor Signalling Prevents Microvascular Dysfunction in Ischaemia/Reperfusion Injury

Objective Activation of thromboxane A2 synthase (TXAS)/thromboxane A2 (TXA2)/thromboxane prostanoid (TP) receptor leads to arterial constriction, platelet aggregation and vascular injury. We attempted to characterize the microvascular dysfunction in ischaemia/reperfusion injury using genetically modified TXAS−/−, TP−/− and TXAS−/−TP−/− mice.

Approach and Results The cardiac micro-circulation and electrocardiograms were evaluated from B6, TXAS−/−, TP−/− and TXAS−/−TP−/− mice in response to intravenous saline, endothelin-1, U46619 (a TXA2 agonist) and myocardial ischaemia/reperfusion injury. Cardiac function was investigated with myocardial permeability, the troponin I concentration and the infarct size. Myocardial TXAS, TP, endothelial nitric oxide (NO) synthase (eNOS), nicotinamide adenine dinucleotide phosphate oxidase 4 (NOx4), 4-hydroxynonenal, interleukin (IL)-1β, cell apoptosis, coronary effluent thromboxane B2 (TXB2) and superoxide anions (O2 −) and NO concentrations were measured. Mice mesenteric reactivity in response to various drugs was assessed by wire myography. In vivo fluorescent platelet adhesiveness to the mesenteric arterial endothelium after FeCl3 stimulation was examined. In B6 mice, ischaemia/reperfusion significantly increased levels of ST-segment elevation, myocardial TXAS, TP, NOx4, IL-1β, apoptosis, coronary endothelin-1, TXB2, O2 − release and the infarct size, with concomitant decreases in eNOS, NO concentrations and cardiac micro-circulation. These effects were remarkably depressed in TXAS−/−, TP−/− and TXAS−/−TP−/− mice. Aspirin treatment or depletion of the TXAS, TP or TXAS/TP gene significantly attenuated the exaggerated vascular reactivity by vasoconstrictors and vasodilators and efficiently reduced platelet adhesion to the mesenteric endothelium under FeCl3 stimulation.

Conclusion Inhibiting TXAS/TXA2/TP signalling confers microvascular protection against oxidative injury in both cardiac and mesenteric arteries.

Deletion of cadherin-17 enhances intestinal permeability and susceptibility to intestinal tumour formation

Cadherin-17 is an adhesion molecule expressed specifically in intestinal epithelial cells. It is frequently underexpressed in human colorectal cancer. The physiological function of cadherin-17 and its role in tumourigenesis have not yet been determined. We used the transcription activator-like effector nuclease technique to generate a Cdh17 knockout (KO) mouse model. Intestinal tissues were analysed with histological, immunohistochemical and ultrastructural methods. Colitis was induced by oral administration of dextran sulphate sodium (DSS), and, to study effects on intestinal tumourigenesis, mice were given azoxymethane (AOM) and DSS to induce colitis-associated cancer. Cdh17 KO mice were viable and fertile. The histology of their small and large intestines was similar to that of wild-type mice. The junctional architecture of the intestinal epithelium was preserved. The loss of cadherin-17 resulted in increased permeability and susceptibility to DSS-induced colitis. The AOM/DSS model demonstrated that Cdh17 KO enhanced tumour formation and progression in the intestine. Increased nuclear translocation of Yap1, but not of β-catenin, was identified in the tumours of Cdh17 KO mice. In conclusion, cadherin-17 plays a crucial role in intestinal homeostasis by limiting the permeability of the intestinal epithelium. Cadherin-17 is also a tumour suppressor for intestinal epithelia. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Differential cell-intrinsic regulations of germinal center B and T cells by miR-146a and miR-146b

Reciprocal interactions between B and follicular T helper (Tfh) cells orchestrate the germinal center (GC) reaction, a hallmark of humoral immunity. Abnormal GC responses could lead to the production of pathogenic autoantibodies and the development of autoimmunity. Here we show that miR-146a controls GC responses by targeting multiple CD40 signaling pathway components in B cells; by contrast, loss of miR-146a in T cells does not alter humoral responses. However, specific deletion of both miR-146a and its paralog, miR-146b, in T cells increases Tfh cell numbers and enhanced GC reactions. Thus, our data reveal differential cell-intrinsic regulations of GC B and Tfh cells by miR-146a and miR-146b. Together, members of the miR-146 family serve as crucial molecular brakes to coordinately control GC reactions to generate protective humoral responses without eliciting unwanted autoimmunity.

In the germinal center (GC), B and T cells interact to induce the production of protective antibodies against threats. Here the authors show that microRNA miR-146a modulates CD40 signaling in GC B cells, while both miR-146a and miR-146b synergize to control GC T cell responses, thereby implicating intricate controls of GC response by miR-146.

The Lupus-Associated Fcγ Receptor IIb-I232T Polymorphism Results in Impairment in the Negative Selection of Low-Affinity Germinal Center B Cells Via c-Abl in Mice

Objective

Fcγ receptor IIb (FcγRIIb) is an essential negative regulator of B cells that blocks B cell receptor (BCR) signaling and triggers c‐Abl–dependent apoptosis of B cells. FcγRIIb‐deficient mice display splenomegaly with expansion of B cells, leading to lupus. FcγRIIb‐I232T is a hypofunctional polymorphism associated with lupus susceptibility in humans, an autoimmune disease linked to diminished deletion of autoreactive B cells. In the context of the FcγRIIb‐I232T polymorphism, we investigated the role of FcγRIIb in the deletion of low‐affinity germinal center (GC) B cells, an important mechanism for preventing autoimmunity.

Methods

We generated FcγRIIb^232T/T mice to mimic human FcγRIIb‐I232T carriers and immunized mice with chicken gamma globulin (CGG)–conjugated NP, a T cell–dependent antigen, to examine the response of GC B cells.

Results

Compared to wild‐type (WT) mice, FcγRIIb^232T/T mice showed increased numbers of low‐affinity NP‐specific IgG and NP‐specific B cells and plasma cells; additionally, the expression of a somatic mutation (W33L) in their V_H186.2 genes encoding high‐affinity BCR was reduced. Notably, FcγRIIb^232T/T mice had a higher number of GC light zone B cells and showed less apoptosis than WT mice, despite having equivalent follicular helper T cell numbers and function. Moreover, phosphorylation of c‐Abl was reduced in FcγRIIb^232T/T mice, and treatment of WT mice with the c‐Abl inhibitor nilotinib during the peak of GC response resulted in reduced affinity maturation reminiscent of FcγRIIb^232T/T mice.

Conclusion

Our findings provide evidence of a critical role of FcγRIIb/c‐Abl in the negative selection of GC B cells in FcγRIIb^232T/T mice. Importantly, our findings indicate potential benefits of up‐regulating FcγRIIb expression in B cells for treatment of systemic lupus erythematosus.

The effects of wild bitter gourd fruit extracts on ICAM-1 expression in pulmonary epithelial cells of C57BL/6J mice and microRNA-221/222 knockout mice: Involvement of the miR-221/-222/PI3K/AKT/NF-κB pathway

BACKGROUND

The extracts from wild bitter gourd fruit (WBGE) were reported to possess numerous pharmacological activities. However, the anti-inflammatory effects of WBGE on human lung epithelial cells and the underlying mechanisms have not been determined.

PURPOSE

To evaluate the molecular basis of the effects of WBGE on intercellular adhesion molecule-1 (ICAM-1) expression in alveolar epithelial (A549) cells, C57BL/6 wild-type (WT) mice and microRNA (miR)-221/-222 knockout (KO) mice with or without tumor necrosis factor (TNF-α; 3 ng/ml) treatment.

STUDY DESIGN/METHODS

WT mice and miR-221/-222 KO mice were fed a control diet and divided into four groups (C: control mice; T: treated with TNF-α alone; WBGE/T: pretreated with WBGE and then stimulated with TNF-α; WBGE: treated with WBGE alone). The effects of WBGE on ICAM-1 expression and the related signals in A549 cells and mice with or without TNF-α treatment were examined by Western blot and immunofluorescent staining.

RESULTS

WBGE significantly decreased the TNF-α-induced ICAM-1 expression in A549 cells through the inhibition of phosphoinositide 3-kinase (PI3K)/ protein kinase B (AKT)/ nuclear factor- kappa B (NF-κB)/ inhibitor of NF-κB (IκB) phosphorylation and decreased leukocyte adhesion. In addition, WBGE reduced endogenous ICAM-1 expression and upregulated miR-221/-222 expression. The overexpression of miR-222 decreased PI3K/AKT/NF-κB/IκB and ICAM-1 expression, which resulted in reducing monocyte adhesion. Moreover, WBGE reduced ICAM-1 expression in lung tissues of WT mice with or without TNF-α treatment and upregulated miR-221/222. WBGE did not affect the miR-221/-222 level and had little effect on ICAM-1 expression in miR-221/-222 KO mice.

CONCLUSIONS

These results suggest that WBGE reduced ICAM-1 expression both under in vitro and in vivo conditions. The protective effects were mediated partly through the miR-221/-222/PI3K/AKT/NF-κB pathway.

Alteration of colonic epithelial cell differentiation in mice deficient for glucosaminyl N-deacetylase/N-sulfotransferase 4

Glucosaminyl N-deacetylase/N-sulfotransferases (NDSTs) are the first enzymes that mediate the initiation of heparan sulfate sulfation. We previously identified NDST4 as a putative tumor suppressor in human colorectal cancer. In the study, we generated an Ndst4 knockout (Ndst4-/-) mouse strain and explored its phenotypic characteristics, particularly in the development of colonic epithelial homeostasis. The Ndst4-deficient mice were viable and fertile, and their life spans were similar to those of wild-type littermates. No gross behavioral or morphological differences were observed between the Ndst4-/- and wild-type mice, and no significant changes were determined in the hematological or serum biochemical parameters of the Ndst4-/- mice. Ndst4 RNA transcripts were expressed in the brain, lung, gastrointestinal tract, pancreas, and ovary. However, Ndst4-null mice exhibited no gross or histological abnormalities in the studied organs, except for the colon. Although no alterations were observed in the crypt length or number of proliferating cells, the Ndst4-/- mice exhibited an increased number of goblet cells and a decreased number of colonocytes in the proximal colon compared with the wild-type mice. Moreover, Ndst4 deficiency increased the basal level of apoptosis in the colonic epithelium. Taken together, we established, for the first time, an Ndst4-/- mouse strain and revealed the involvement of Ndst4 in the development and homeostasis of colonic epithelium. Accordingly, NDST4 in human colon might direct the biosynthesis of specific heparan sulfate proteoglycans that are essential for the maintenance of colonic epithelial homeostasis. Thus, the loss of its function may result in the tumorigenesis and progression of colorectal cancer.

The ubiquitin ligase ZNRF1 promotes caveolin-1 ubiquitination and degradation to modulate inflammation

Caveolin-1 (CAV1), the major constituent of caveolae, plays a pivotal role in various cellular biological functions, including cancer and inflammation. The ubiquitin/proteasomal pathway is known to contribute to the regulation of CAV1 expression, but the ubiquitin ligase responsible for CAV1 protein stability remains unidentified. Here we reveal that E3 ubiquitin ligase ZNRF1 modulates CAV1 protein stability to regulate Toll-like receptor (TLR) 4-triggered immune responses. We demonstrate that ZNRF1 physically interacts with CAV1 in response to lipopolysaccharide and mediates ubiquitination and degradation of CAV1. The ZNRF1-CAV1 axis regulates Akt-GSK3β activity upon TLR4 activation, resulting in enhanced production of pro-inflammatory cytokines and inhibition of anti-inflammatory cytokine IL-10. Mice with deletion of ZNRF1 in their hematopoietic cells display increased resistance to endotoxic and polymicrobial septic shock due to attenuated inflammation. Our study defines ZNRF1 as a regulator of TLR4-induced inflammatory responses and reveals another mechanism for the regulation of TLR4 signalling through CAV1.

Resveratrol attenuates ICAM-1 expression and monocyte adhesiveness to TNF-α-treated endothelial cells: evidence for an anti-inflammatory cascade mediated by the miR-221/222/AMPK/p38/NF-κB pathway

Resveratrol, an edible polyphenolic phytoalexin, improves endothelial dysfunction and attenuates inflammation. However, the mechanisms have not been thoroughly elucidated. Therefore, we investigated the molecular basis of the effects of resveratrol on TNF-α-induced ICAM-1 expression in HUVECs. The resveratrol treatment significantly attenuated the TNF-α-induced ICAM-1 expression. The inhibition of p38 phosphorylation mediated the reduction in ICAM-1 expression caused by resveratrol. Resveratrol also decreased TNF-α-induced IκB phosphorylation and the phosphorylation, acetylation, and translocation of NF-κB p65. Moreover, resveratrol induced the AMPK phosphorylation and the SIRT1 expression in TNF-α-treated HUVECs. Furthermore, TNF-α significantly suppressed miR-221/-222 expression, which was reversed by resveratrol. miR-221/-222 overexpression decreased p38/NF-κB and ICAM-1 expression, which resulted in reduced monocyte adhesion to TNF-α-treated ECs. In a mouse model of acute TNF-α-induced inflammation, resveratrol effectively attenuated ICAM-1 expression in the aortic ECs of TNF-α-treated wild-type mice. These beneficial effects of resveratrol were lost in miR-221/222 knockout mice. Our data showed that resveratrol counteracted the TNF-α-mediated reduction in miR-221/222 expression and decreased the TNF-α-induced activation of p38 MAPK and NF-κB, thereby suppressing ICAM-1 expression and monocyte adhesion. Collectively, our results show that resveratrol attenuates endothelial inflammation by reducing ICAM-1 expression and that the protective effect was mediated partly through the miR-221/222/AMPK/p38/NF-κB pathway.

Current animal models of hemophilia: the state of the art

Hemophilia is the most well-known hereditary bleeding disorder, with an incidence of one in every 5000 to 30,000 males worldwide. The disease is treated by infusion of protein products on demand and as prophylaxis. Although these therapies have been very successful, some challenging and unresolved tasks remain, such as reducing bleeding rates, presence of target joints and/or established joint damage, eliminating the development of inhibitors, and increasing the success rate of immune-tolerance induction (ITI). Many preclinical trials are carried out on animal models for hemophilia generated by the hemophilia research community, which in turn enable prospective clinical trials aiming to tackle these challenges. Suitable animal models are needed for greater advances in treating hemophilia, such as the development of better models for evaluation of the efficacy and safety of long-acting products, more powerful gene therapy vectors than are currently available, and successful ITI strategies. Mice, dogs, and pigs are the most commonly used animal models for hemophilia. With the advent of the nuclease method for genome editing, namely the CRISPR/Cas9 system, it is now possible to create animal models for hemophilia other than mice in a short period of time. This review presents currently available animal models for hemophilia, and discusses the importance of animal models for the development of better treatment options for hemophilia.

Lack of Thromboxane Synthase Prevents Hypertension and Fetal Growth Restriction after High Salt Treatment during Pregnancy

Preeclampsia (PE) is a potentially fatal pregnancy-related hypertensive disorder characterized by poor placenta development that can cause fetal growth restriction. PE-associated pathologies, including thrombosis, hypertension, and impaired placental development, may result from imbalances between thromboxane A₂ (TXA₂) and prostacyclin. Low-dose aspirin, which selectively inhibits TXA₂ production, is used to prevent high-risk PE. However, the role of TXA₂ in aspirin-mediated protective effects in women with PE is not understood fully. In this study, we examined the role of prostanoids in PE using human samples and an induced PE mouse model. We demonstrated that the administration of salted drinking water (2.7% NaCl) to wild-type mice resulted in elevated placental TXA₂ synthase (TXAS) and plasma TXA₂, but not prostacyclin, levels, which was also found in our clinical PE placenta samples. The high salt-treated wild-type pregnant mice had shown unchanged maternal body weight, hypertension (MAP increase 15 mmHg), and decreased pup weight (~50%) and size (~24%), but these adverse effects were ameliorated in TXAS knockout (KO) mice. Moreover, increased expression of interleukin-1β and downstream phosphorylated-p38-mitogen-activated protein kinase were concordant with apoptosis induction in the placentas of salt water-treated wild-type mice. These alterations were not observed in TXAS KO mice. Together, our data suggest that TXA₂ depletion has anti-PE effects due to the prevention of hypertension and placental damage through downregulation of the interleukin-1β pathway.

Abstract B44: Accelerated mouse colorectal cancer progression in the presence of EHMT2 overexpression

In the last 5 years, the prevalence of colorectal cancer (CRC) has increased worldwide and has surpassed that of liver cancer. Even after treatment for primary CRC, patients still have a high risk (30%–50%) of cancer recurrence, generally from metastasis. Thus, if we can uncover the progressive mechanisms of CRC and identify a novel drug target, current treatment regimens and the survival of patients with advanced stage CRC can be improved. Euchromatin histone lysine N-methyl transferase 2 (EHMT2) inhibition is considered an effective therapeutic strategy for cancer treatment because its inhibitors, BIX-01294 and UNC0639, can induce autophagy-dependent cell death. However, the function of EHMT2 in CRC progression remains largely unclear. In this study, we established a colonic stem-cell-specific EHMT2 activation combined with sporadic (AOM/DSS-induced) or hereditary (Apc mutant) CRC mouse models. In the EHMT2-overexpressed group, many colonic tumors larger than 3 mm in size were found in the 24 weeks after tumor induction. Histological analysis of these tumors showed that the adenocarcinomatous glands became highly irregular, and these glands were difficult to discern, one of the characteristic of malignant CRC. In the 52 weeks after tumor induction, we reproducibly observed CRC liver metastases. Further analysis by RNA sequencing combined with gene set enrichment analysis determined that the anti-apoptosis-related and Wnt-signaling gene sets can be enriched in the EHMT2-overexpressed group. Using the chromatin immunoprecipitation assay, we demonstrated that EHMT2 directly targeted the caspase8 proximal promoter region and increased the level of H3 lysine9 di-methylation in this region. Several functional assays supported that this gene regulation may have conferred opportunities for CRC cells to avoid the cytotoxicity of anticancer drugs. Overall, aberrant EHMT2 expression is conducive to CRC progression.

Citation Format: Kang-Yu Tai, I-Shing Yu, Shih-Ting Cha, Shu-Wha Lin, Min-Liang Kuo, You-Tzung Chen. Accelerated mouse colorectal cancer progression in the presence of EHMT2 overexpression. [abstract]. In: Proceedings of the AACR Special Conference on Chromatin and Epigenetics in Cancer; Sep 24-27, 2015; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2016;76(2 Suppl):Abstract nr B44.

A Single miRNA-mRNA Interaction Affects the Immune Response in a Context- and Cell-Type-Specific Manner

MicroRNA (miRNA)-dependent regulation of gene expression confers robustness to cellular phenotypes and controls responses to extracellular stimuli. Although a single miRNA can regulate expression of hundreds of target genes, it is unclear whether any of its distinct biological functions can be due to the regulation of a single target. To explore in vivo the function of a single miRNA-mRNA interaction, we mutated the 3' UTR of a major miR-155 target (SOCS1) to specifically disrupt its regulation by miR-155. We found that under physiologic conditions and during autoimmune inflammation or viral infection, some immunological functions of miR-155 were fully or largely attributable to the regulation of SOCS1, whereas others could be accounted only partially or not at all by this interaction. Our data suggest that the role of a single miRNA-mRNA interaction is dependent on cell type and biological context.

Sun1 deficiency leads to cerebellar ataxia in mice

Migration and organization of the nucleus are essential for the proliferation and differentiation of cells, including neurons. However, the relationship between the positioning of the nucleus and cellular morphogenesis remains poorly understood. Inherited recessive cerebellar ataxia has been attributed to mutations in SYNE1, a component of the linker of nucleoskeleton and cytoskeleton (LINC) complex. Regardless, Syne1-mutant mice present with normal cerebellar development. The Sad1-Unc-84 homology (SUN)-domain proteins are located at the inner nuclear membrane and recruit Syne proteins through the KASH domain to the outer nuclear membrane. Here, we report an unrecognized contribution of Sun1 and Sun2 to the postnatal development of murine cerebellum. Mice depleted of Sun1 showed a marked reduction in the cerebellar volume, and this phenotype is exacerbated with additional loss of a Sun2 allele. Consistent with these histological changes, Sun1(-/-) and Sun1(-/-)Sun2(+/-) mice exhibited defective motor coordination. Results of immunohistochemical analyses suggested that Sun1 is highly expressed in Purkinje cells and recruits Syne2 to the periphery of the nucleus. Approximately 33% of Purkinje cells in Sun1(-/-) mice and 66% of Purkinje cells in Sun1(-/-)Sun2(+/-) mice were absent from the surface of the internal granule layer (IGL), whereas the proliferation and migration of granule neurons were unaffected. Furthermore, the Sun1(-/-)Sun2(+/-) Purkinje cells exhibited retarded primary dendrite specification, reduced dendritic complexity and aberrant patterning of synapses. Our findings reveal a cell-type-specific role for Sun1 and Sun2 in nucleokinesis during cerebellar development, and we propose the use of Sun-deficient mice as a model for studying cerebellar ataxia that is associated with mutation of human SYNE genes or loss of Purkinje cells.

NRIP is a novel Z-disc protein to activate calmodulin signaling for skeletal muscle contraction and regeneration

Nuclear receptor interaction protein (NRIP, also known as DCAF6 and IQWD1) is a calcium-dependent calmodulin binding protein (Ca2+/CaM). In this study, we found that NRIP is a novel Z-disc protein in skeletal muscle. NRIP knockout mice (NRIP KO) were generated and found to have reduced muscle strength, susceptibility to fatigue and impaired adaptive exercise performance. The mechanisms of NRIP-regulated muscle contraction depend on NRIP being downstream of calcium signaling, where it stimulates phosphorylation of both calcineurin-nuclear factor of activated T-cells, cytoplasmic 1 (CaN-NFATc1) and calmodulin-dependent protein kinase II (CaMKII) through interaction with CaM, resulting in the induction of slow myosin gene expression and mitochondrial activity, and balancing of Ca2+ homeostasis of the internally stored Ca2+ of the sarcoplasmic reticulum. Moreover, NRIP KO mice have delayed regenerative capacity. The amount of NRIP can be enhanced after muscle injury and is responsible for muscle regeneration, coupled with the increased expression of myogenin, desmin and embryonic myosin heavy chain for myogenesis, as well as myotube formation. In conclusion, NRIP is a novel Z-disc protein important for skeletal muscle strength and regenerative capacity.

A nucleolus-predominant piggyBac transposase, NP-mPB, mediates elevated transposition efficiency in mammalian cells

PiggyBac is a prevalent transposon system used to deliver transgenes and functionally explore the mammalian untouched genomic territory. The important features of piggyBac transposon are the relatively low insertion site preference and the ability of seamless removal from genome, which allow its potential uses in functional genomics and regenerative medicine. Efforts to increase its transposition efficiency in mammals were made through engineering the corresponding transposase (PBase) codon usage to enhance its expression level and through screening for mutant PBase variants with increased enzyme activity. To improve the safety for its potential use in regenerative medicine applications, site-specific transposition was achieved by using engineered zinc finger- and Gal4-fused PBases. An excision-prone PBase variant has also been successfully developed. Here we describe the construction of a nucleolus-predominant PBase, NP-mPB, by adding a nucleolus-predominant (NP) signal peptide from HIV-1 TAT protein to a mammalian codon-optimized PBase (mPB). Although there is a predominant fraction of the NP-mPB-tGFP fusion proteins concentrated in the nucleoli, an insertion site preference toward nucleolar organizer regions is not detected. Instead a 3–4 fold increase in piggyBac transposition efficiency is reproducibly observed in mouse and human cells.

Phosphorylation regulates NCC stability and transporter activity in vivo

A T60M mutation in the thiazide-sensitive sodium chloride cotransporter (NCC) is common in patients with Gitelman's syndrome (GS). This mutation prevents Ste20-related proline and alanine-rich kinase (SPAK)/oxidative stress responsive kinase-1 (OSR1)-mediated phosphorylation of NCC and alters NCC transporter activity in vitro. Here, we examined the physiologic effects of NCC phosphorylation in vivo using a novel Ncc T58M (human T60M) knock-in mouse model. Ncc(T58M/T58M) mice exhibited typical features of GS with a blunted response to thiazide diuretics. Despite expressing normal levels of Ncc mRNA, these mice had lower levels of total Ncc and p-Ncc protein that did not change with a low-salt diet that increased p-Spak. In contrast to wild-type Ncc, which localized to the apical membrane of distal convoluted tubule cells, T58M Ncc localized primarily to the cytosolic region and caused an increase in late distal convoluted tubule volume. In MDCK cells, exogenous expression of phosphorylation-defective NCC mutants reduced total protein expression levels and membrane stability. Furthermore, our analysis found diminished total urine NCC excretion in a cohort of GS patients with homozygous NCC T60M mutations. When Wnk4(D561A/+) mice, a model of pseudohypoaldosteronism type II expressing an activated Spak/Osr1-Ncc, were crossed with Ncc(T58M/T58M) mice, total Ncc and p-Ncc protein levels decreased and the GS phenotype persisted over the hypertensive phenotype. Overall, these data suggest that SPAK-mediated phosphorylation of NCC at T60 regulates NCC stability and function, and defective phosphorylation at this residue corrects the phenotype of pseudohypoaldosteronism type II.

Differences in the pathogenicity of the p.H723R mutation of the common deafness-associated SLC26A4 gene in humans and mice

Mutations in the SLC26A4 gene are a common cause of human hereditary hearing impairment worldwide. Previous studies have demonstrated that different SLC26A4 mutations have different pathogenetic mechanisms. By using a genotype-driven approach, we established a knock-in mouse model (i.e., Slc26a4^{tm2Dontuh/tm2Dontuh} mice) homozygous for the common p.H723R mutation in the East Asian population. To verify the pathogenicity of the p.H723R allele in mice, we further generated mice with compound heterozygous mutations (i.e., Slc26a4^{tm1Dontuh/tm2Dontuh}) by intercrossing Slc26a4^+/tm2Dontuh mice with Slc26a4^{tm1Dontuh/tm1Dontuh} mice, which segregated the c.919-2A>G mutation with an abolished Slc26a4 function. Mice were then subjected to audiologic assessments, a battery of vestibular evaluations, inner ear morphological studies, and noise exposure experiments. The results were unexpected; both Slc26a4^{tm2Dontuh/tm2Dontuh} and Slc26a4^{tm1Dontuh/tm2Dontuh} mice showed normal audiovestibular phenotypes and inner ear morphology, and they did not show significantly higher shifts in hearing thresholds after noise exposure than the wild-type mice. The results indicated not only the p.H723R allele was non-pathogenic in mice, but also a single p.H723R allele was sufficient to maintain normal inner ear physiology in heterozygous compound mice. There might be discrepancies in the pathogenicity of specific SLC26A4 mutations in humans and mice; therefore, precautions should be taken when extrapolating the results of animal studies to humans.

Incorporation of the factor IX Padua mutation into FIX-Triple improves clotting activity in vitro and in vivo

Using gain-of-function factor IX (FIX) for replacement therapy for haemophilia B (HB) is an attractive strategy. We previously reported a high-activity FIX, FIX-Triple (FIX-V86A/E277A/R338A) as a good substitute for FIX-WT (wild-type) in protein replacement therapy, gene therapy, and cell therapy. Here we generated a new recombinant FIX-TripleL (FIX-V86A/E277A/R338L) by replacing the alanine at residue 338 of FIX-Triple with leucine as in FIX-Padua (FIX-R338L). Purified FIX-TripleL exhibited 22-fold higher specific clotting activity and 15-fold increased binding affinity to activated FVIII compared to FIX-WT. FIX-TripleL increased the therapeutic potential of FIX-Triple by nearly 100% as demonstrated with calibrated automated thrombogram and thromboelastography. FIX-TripleL demonstrated a normal clearance rate in HB mice. The clotting activity of FIX-TripleL was consistently 2- to 3-fold higher in these mice than that of FIX-Triple or FIX-R338L. Gene delivery of adeno-associated virus (AAV) in HB mice showed that FIX-TripleL had 15-fold higher specific clotting activity than FIX-WT, and this activity was significantly better than FIX-Triple (10-fold) or FIX-R338L (6-fold). At a lower viral dose, FIX-TripleL improved FIX activity from sub-therapeutic to therapeutic levels. Under physiological conditions, no signs of adverse thrombotic events were observed in long-term AAV-FIX-treated C57Bl/6 mice. Hepatocellular adenomas were observed in the high- but not the medium- or the low-dose AAV-treated mice expressing FIX-WT or FIX-Triple, indicating the advantages of using hyperfunctional FIX variants to reduce viral doses while maintaining therapeutic clotting activity. Thus, incorporation of the FIX Padua mutation significantly improves the clotting function of FIX-Triple so as to optimise protein replacement therapy and gene therapy.

A knock-in Npm1 mutation in mice results in myeloproliferation and implies a perturbation in hematopoietic microenvironment

Somatic Nucleophosmin (NPM1) mutation frequently occurs in acute myeloid leukemia (AML), but its role in leukemogenesis remains unclear. This study reports the first "conventional" knock-in mouse model of Npm1 mutation, which was achieved by inserting TCTG after nucleotide c.857 (c.854_857dupTCTG) to mimic human mutation without any "humanized" sequence. The resultant mutant peptide differed slightly different from that in humans but exhibited cytoplasmic pulling force. Homozygous (Npm1(c+/c+)) mice showed embryonic lethality before day E8.5, wheras heterozygous (Npm1(wt/c+)) mice appeared healthy at birth and were fertile. Approximately 36% of Npm1(wt/c+) mice developed myeloproliferative disease (MPD) with extramedullary hematopoiesis. Those Npm1(wt/c+) mice that did not develop MPD nevertheless gradually developed monocytosis and showed increased numbers of marrow myeloid precursors. This second group of Npm1(wt/c+) mice also showed compromised cobblestone area formation, suggesting pathology in the hematopoietic niche. Microarray experiments and bioinformatic analysis on mice myeloid precursor cells and 227 human samples revealed the expression of CXCR4/CXCL12-related genes was significantly suppressed in mutant cells from both mice and humans. Thus, our mouse model demonstrated that Npm1 mutation can result in MPD, but is insufficient for leukemogenesis. Perturbation of hematopoietic niche in mutant hematopoietic stem cells (implied by underrepresentation of CXCR4/CXCL12-related genes) may be important in the pathogenesis of NPM1 mutations.

Serine protease hepsin regulates hepatocyte size and hemodynamic retention of tumor cells by hepatocyte growth factor signaling in mice

The liver architecture plays an important role in maintaining hemodynamic balance, but the mechanisms that underlie this role are not fully understood. Hepsin, a type II transmembrane serine protease, is predominantly expressed in the liver, but has no known physiological functions. Here, we report that hemodynamic balance in the liver is regulated through hepsin. Deletion of hepsin (hepsin(-/-) ) in mice resulted in enlarged hepatocytes and narrowed liver sinusoids. Using fluorescent microbeads and antihepsin treatment, we demonstrated that metastatic cancer cells preferentially colonized the hepsin(-/-) mouse liver as a result of the retention of tumor cells because of narrower sinusoids. The enlarged hepatocytes expressed increased levels of connexin, which resulted from defective prohepatocyte growth factor (pro-HGF) processing and decreased c-Met phosphorylation in the livers of hepsin(-/-) mice. Treatment of hepsin(-/-) mice with recombinant HGF rescued these phenotypes, and treatment of wild-type mice with an HGF antagonist recapitulated the phenotypes observed in hepsin(-/-) mice.

CONCLUSION

Our findings show that the maintenance of hepatic structural homeostasis occurs through HGF/c-Met/connexin signaling by hepsin, and hepsin-mediated changes in liver architecture significantly enhance tumor metastasis to the liver.

R26R-GR: a Cre-activable dual fluorescent protein reporter mouse

Green fluorescent protein (GFP) and its derivatives are the most widely used molecular reporters for live cell imagining. The development of organelle-specific fusion fluorescent proteins improves the labeling resolution to a higher level. Here we generate a R26 dual fluorescent protein reporter mouse, activated by Cre-mediated DNA recombination, labeling target cells with a chromatin-specific enhanced green fluorescence protein (EGFP) and a plasma membrane-anchored monomeric cherry fluorescent protein (mCherry). This dual labeling allows the visualization of mitotic events, cell shapes and intracellular vesicle behaviors. We expect this reporter mouse to have a wide application in developmental biology studies, transplantation experiments as well as cancer/stem cell lineage tracing.

The role of nocturnin in early adipogenesis and modulation of systemic insulin resistance in human

The deadenylase nocturnin (Noc, Ccrn4l) has been recently found to regulate lipid metabolism and to control preadipocyte differentiation. Here, we showed that among the five deadenylases tested, Noc and Pan2 exhibited a biphasic expression which is out of phase to each other during adipocyte differentiation of 3T3-L1 cells. The expression levels of other deadenylases, including Parn, Ccr4, and Caf1, were relatively unchanged or reduced. The immediate early expressed Noc during 3T3-L1 adipogenesis was involved in regulating mitotic clonal expansion (MCE) and cyclin D1 expression, as demonstrated in Noc-silenced 3T3-L1 cells and Noc(-/-) primary mouse embryonic fibroblasts (MEFs). Transcriptional profiling of Noc-depleted 3T3-L1 adipocytes revealed that most of the differentially expressed genes were related to cell growth and proliferation. In human adipose tissue, NOC mRNA level negatively associated with both fasting serum insulin and homeostasis model assessment of insulin resistance, and positively associated with both adiponectin mRNA levels and circulating adiponectin levels. Taken together, these results suggest the role of Noc in the modulation of early adipogenesis as well as systemic insulin sensitivity.

Rescue of the genetically engineered Cul4b mutant mouse as a potential model for human X-linked mental retardation

Mutation in CUL4B, which encodes a scaffold protein of the E3 ubiquitin ligase complex, has been found in patients with X-linked mental retardation (XLMR). However, early deletion of Cul4b in mice causes prenatal lethality, which has frustrated attempts to characterize the phenotypes in vivo. In this report, we successfully rescued Cul4b mutant mice by crossing female mice in which exons 4-5 of Cul4b were flanked by loxP sequences with Sox2-Cre male mice. In Cul4b-deficient (Cul4b(Δ)/Y) mice, no CUL4B protein was detected in any of the major organs, including the brain. In the hippocampus, the levels of CUL4A, CUL4B substrates (TOP1, β-catenin, cyclin E and WDR5) and neuronal markers (MAP2, tau-1, GAP-43, PSD95 and syn-1) were not sensitive to Cul4b deletion, whereas the number of parvalbumin (PV)-positive GABAergic interneurons was decreased in Cul4b(Δ)/Y mice, especially in the dentate gyrus (DG). Some dendritic features, including the complexity, diameter and spine density in the CA1 and DG hippocampal neurons, were also affected by Cul4b deletion. Together, the decrease in the number of PV-positive neurons and altered dendritic properties in Cul4b(Δ)/Y mice imply a reduction in inhibitory regulation and dendritic integration in the hippocampal neural circuit, which lead to increased epileptic susceptibility and spatial learning deficits. Our results identify Cul4b(Δ)/Y mice as a potential model for the non-syndromic model of XLMR that replicates the CUL4B-associated MR and is valuable for the development of a therapeutic strategy for treating MR.

Mutation screening of the EYA1, SIX1, and SIX5 genes in an East Asian cohort with branchio-oto-renal syndrome

OBJECTIVES/HYPOTHESIS

To explore the genetic characteristics of branchio-oto-renal (BOR) syndrome in an East Asian population.

STUDY DESIGN

Prospective clinical genetic study.

METHODS

Twelve families (total of 18 patients) who fulfilled the criteria for BOR syndrome were enrolled in this study. Mutation screening of the EYA1, SIX1, and SIX5 genes was performed by direct sequencing and quantitative polymerase chain reaction, and genotype-phenotype correlation was investigated.

RESULTS

Two novel EYA1 variants, c.466C>T (p.Q156X) and c.1735delG (p.D579fs), were identified in two multiplex families. The c.466C>T variant resulted in a truncated EYA1 protein, whereas the c.1735delG variant was predicted to encode an EYA1 protein with an abnormal C terminal. Neither variant was identified in a panel of 100 normal controls, and both were cosegregated with the BOR phenotype in the pedigrees, indicating that they were pathogenic mutations. No SIX1 and SIX5 mutations were detected in members of the remaining 10 families. Analysis of the genotype-phenotype correlation revealed a high phenotypic variability between and within BOR families.

CONCLUSIONS

Two novel EYA1 mutations (c.466C>T and c.1735delG) were identified in two families with BOR syndrome. SIX1 and SIX5 mutations were not detected in the present study. Further investigation is warranted regarding the contribution of SIX1 and SIX5 mutations to BOR syndrome in East Asian populations.

Establishment of a knock-in mouse model with the SLC26A4 c.919-2A>G mutation and characterization of its pathology

Recessive mutations in the SLC26A4 gene are a common cause of hereditary hearing impairment worldwide. Previous studies have demonstrated that different SLC26A4 mutations may have different pathogenetic mechanisms. In the present study, we established a knock-in mouse model (i.e., Slc26a4^{tm1Dontuh/tm1Dontuh} mice) homozygous for the c.919-2A>G mutation, which is a common mutation in East Asians. Mice were then subjected to audiologic assessment, a battery of vestibular evaluations, and inner ear morphological studies. All Slc26a4^{tm1Dontuh/tm1Dontuh} mice revealed profound hearing loss, whereas 46% mice demonstrated pronounced head tilting and circling behaviors. There was a significant difference in the vestibular performance between wild-type and Slc26a4^{tm1Dontuh/tm1Dontuh} mice, especially those exhibiting circling behavior. Inner ear morphological examination of Slc26a4^{tm1Dontuh/tm1Dontuh} mice revealed an enlarged endolymphatic duct, vestibular aqueduct and sac, atrophy of stria vascularis, deformity of otoconia in the vestibular organs, consistent degeneration of cochlear hair cells, and variable degeneration of vestibular hair cells. Audiologic and inner ear morphological features of Slc26a4^{tm1Dontuh/tm1Dontuh} mice were reminiscent of those observed in humans. These features were also similar to those previously reported in both knock-out Slc26a4^−/− mice and Slc26a4^loop/loop mice with the Slc26a4 p.S408F mutation, albeit the severity of vestibular hair cell degeneration appeared different among the three mouse strains.

Gene targeting and expression analysis of mouse Tem1/endosialin using a lacZ reporter

TEM1 (endosialin) expression is increased in the stroma and tumor vasculature of several common human cancers. The exact physiological role of TEM1 is still unknown since Tem1-deficient mice are viable and show only a lower rate of abdominal site-specific tumor invasion in tumor transplantation experiments. Previous studies have reported Tem1 expression in mouse embryos and adults, but did not determine the timing or location of the earliest expression, and did not examine all organ systems. Using the highly sensitive Bluo-Gal staining method for detecting temporal and spatial Tem1-lacZ activity in lacZ knock-in (+/lacZ) mice, we found that Tem1 gene expression was initially detectable in the dorsal aortic wall, the heart, the umbilical vessels, the first branchial arch, and the cephalic mesenchyme at E9.5. From E10.5 to E14.5, Tem1 gene expression was additionally seen mainly in the genital tubercle, the mesonephros, the whisker follicles, the mesenchymal tissues around the eye, and the lung. Remarkably, the kidney expressed abundant Tem1-lacZ starting from E16.5. Postnatally, Tem1 expression decreased in most organs but elevated expression persisted in the renal glomerulus and the uterus, where the expression pattern varied at different estrous cycle stages. Co-localization studies indicated that most vimentin-positive cells co-expressed Tem1-lacZ, while a large portion of CD31- or desmin-positive cells were also positive for Tem1-lacZ. Taken together, our observations suggest that Tem1 is expressed throughout embryonic and adult development in several types of mesenchymal cells closely related to blood vessels.

SEPT12 deficiency causes sperm nucleus damage and developmental arrest of preimplantation embryos

Oocytes fertilized with spermatozoa obtained from Septin 12+/- chimeric mice failed to develop beyond the morula stage after IVF and intracytoplasmic sperm injection because of significant DNA defects in the spermatozoa. Given that SEPT12 is expressed at the edge of the sperm nucleus in both humans and mice, we hypothesized the vital roles of Septin 12 in sperm head shaping, nuclear DNA condensation, and early embryonic development.

Generation and analysis of the thiazide-sensitive Na+ -Cl- cotransporter (Ncc/Slc12a3) Ser707X knockin mouse as a model of Gitelman syndrome

Gitelman syndrome (GS) is characterized by salt-losing hypotension, hypomagnesemia, hypokalemic metabolic alkalosis, and hypocalciuria. To better model human GS caused by a specific mutation in the thiazide-sensitive Na(+) -Cl(-) cotransporter (NCC) gene SLC12A3, we generated a nonsense Ncc Ser707X knockin mouse corresponding to human p.Ser710X (c.2135C>A), a recurrent mutation with severe phenotypes in Chinese GS patients. Compared with wild-type or heterozygous littermates, homozygous (Hom) knockin mice fully recapitulated the phenotype of human GS. The markedly reduced Ncc mRNA and virtually absent Ncc protein expression in kidneys of Hom mice was primarily due to nonsense-mediated mRNA decay (NMD) surveillance mechanisms. Expression of epithelial Na(+) channel (Enac), Ca(2+) channels (Trpv5 and Trpv6), and K(+) channels (Romk1 and maxi-K) were significantly increased. Late distal convoluted tubules (DCT) volume was increased and DCT cell ultrastructure appeared intact. High K(+) intake could not correct hypokalemia but caused a further increase in maxi-K but not Romk1 expression. Renal tissue from a patient with GS also showed the enhanced TRPV5 and ROMK1 expression in distal tubules. We suggest that the upregulation of TRPV5/6 and of ROMK1 and Maxi-K may contribute to hypocalciuria and hypokalemia in Ncc Ser707X knockin mice and human GS, respectively.

FIX-Triple, a gain-of-function factor IX variant, improves haemostasis in mouse models without increased risk of thrombosis

Engineered recombinant factor IX (FIX) with augmented clotting activity may prove useful for replacement therapy, but it has not been studied for risk of thrombosis. We used three mouse models to evaluate thrombosis risk associated with the FIX variant FIX-Triple, which has a 13-fold higher specific activity than wild-type FIX (FIX-WT). Protein infusion of FIX-Triple into haemophilia B mice was not thrombogenic, even at a dose of 13-fold higher than FIX-WT. Gene knock-in to generate mice that constitutively produce FIX-WT or FIX-Triple protein revealed that all mice expressed equal antigen levels. FIX-Triple knock-in mice that exhibited 10-fold higher FIX clotting activity did not show hypercoagulation. Adeno-associated viral (AAV) delivery of the FIX gene into mice was used to mimic gene therapy. Haemophilia B and inbred C57Bl/6 mice injected with different doses of virus particles carrying FIX-WT or FIX-Triple and expressing up to a nearly 13-fold excess (1289% of normal) of FIX clotting activity did not show increased risk of thrombosis compared with untreated wild-type mice in a normal haemostatic state. When challenged with ferric chloride (FeCl3), the mesenteric venules of AAV-treated C57Bl/6 mice that gave a nearly five-fold excess (474%) of FIX clotting activity were not thrombotic; however, thrombosis became obvious in FeCl3-challenged mice expressing extremely high FIX clotting activities (976-1289%) achieved by AAV delivery of FIX-Triple. These studies suggest that FIX-Triple is not thrombogenic at therapeutic levels and is a potential therapeutic substitute for FIX-WT.

Genetic modification of donor hepatocytes improves therapeutic efficacy for hemophilia B in mice

Hepatocyte transplantation (Tx) holds promise for curing genetic liver diseases. However, a limited number of donor hepatocytes can be transplanted into the host liver. Recipient preconditioning and donor cell engineering are under investigation to improve cell engraftment. In theory, genetically engineered cells secreting therapeutic proteins with superior function could compensate for poor engraftment efficiency. We have generated a bioengineered human coagulation factor IX (FIX) with augmented specific activity (named FIX-Triple). The aim of this study was to evaluate therapeutic efficacy of cell therapy using hemophilia B (HB) as a disease model by transplanting FIX-Triple-secreting hepatocytes. The donor hepatocytes were isolated from FIX-Triple knock-in (KI) or FIX-WT (wild-type) KI mice and transplanted intrasplenically into FIX knock-out (KO) mice. FIX-Triple KI recipients exhibited fourfold higher plasma FIX clotting activity than FIX-WT KI recipients. By repeated Txs, the clotting activity of FIX-Triple KI recipients even increased to more than 10% of normal mouse plasma. The engraftment and FIX production efficiencies of transplanted cells were equivalent between the FIX-WT KI and FIX-Triple KI donors. A hemostatic function assay showed that FIX-Triple KI recipients with repeated Txs had more enhanced clot kinetics and a greater maximum rate of thrombus generation than those with a single Tx. Moreover, FIX inhibitors in these recipients rarely developed. In conclusion, hepatocyte Tx with genetically engineered donor cells is an effective therapeutic strategy for HB.

The expression level of septin12 is critical for spermiogenesis

Septins belong to a family of polymerizing GTP-binding proteins that are required for many cellular functions, such as membrane compartmentalization, vesicular trafficking, mitosis, and cytoskeletal remodeling. One family member, septin12, is expressed specifically in the testis. In this study, we found septin12 expressed in multiple subcellular compartments during terminal differentiation of mouse germ cells. In humans, the testicular tissues of men with either hypospermatogenesis or maturation arrest had lower levels of SEPTIN12 transcripts than normal men. In addition, increased numbers of spermatozoa with abnormal head, neck, and tail morphologies lacked SEPT12 immunostaining signals, as compared with normal spermatozoa. To elucidate the role of septin12, we generated 129 embryonic stem cells containing a septin12 mutant allele with a deletion in the exons that encode the N-terminal GTP-binding domain. Most chimeras derived from the targeted embryonic stem cells were infertile, and the few fertile chimeras only produced offspring with a C57BL/6 background. Semen analysis of the infertile chimeras showed a decreased sperm count, decreased sperm motility, and spermatozoa with defects involving all subcellular compartments. The testicular phenotypes included maturation arrest of germ cells at the spermatid stage, sloughing of round spermatids, and increased apoptosis of germ cells. Electron microscopic examination of spermatozoa showed misshapen nuclei, disorganized mitochondria, and broken acrosomes. Our data indicate that Septin12 expression levels are critical for mammalian spermiogenesis.

Mice deficient in collapsin response mediator protein-1 exhibit impaired long-term potentiation and impaired spatial learning and memory

Collapsing response mediator protein-1 (CRMP-1) was initially identified in brain and has been implicated in plexin-dependent neuronal function. The high amino acid sequence identity among the five CRMPs has hindered determination of the functions of each individual CRMP. We generated viable and fertile CRMP-1 knock-out (CRMP-1(-/-)) mice with no evidence of gross abnormality in the major organs. CRMP-1(-/-) mice exhibited intense microtubule-associated protein 2 (MAP2) staining in the proximal portion of the dendrites, but reduced and disorganized MAP2 staining in the distal dendrites of hippocampal CA1 pyramidal cells. Immunoreactivity to GAP-43 (growth-associated protein-43) and PSD95 (postsynaptic density-95) (a postsynaptic membrane adherent cytoskeletal protein) was also decreased in the CA1 region of the knock-out mice. These changes were consistent with the mutant mice showing a reduction in long-term potentiation (LTP) in the CA1 region and impaired performance in hippocampal-dependent spatial learning and memory tests. CRMP-1(-/-) mice showed a normal synapsin I labeling pattern in CA1 and normal paired-pulse facilitation. These findings provide the first evidence suggesting that CRMP-1 may be involved in proper neurite outgrowth in the adult hippocampus and that loss of CRMP-1 may affect LTP maintenance and spatial learning and memory.