scholarly journals Humanized Mcl-1 mice enable accurate pre-clinical evaluation of MCL-1 inhibitors destined for clinical use

2018 ◽  
Author(s):  
Margs S. Brennan ◽  
Catherine Chang ◽  
Grant Dewson ◽  
Lin Tai ◽  
Guillaume Lessene ◽  
...  

SUMMARYMCL-1 is a pro-survival BCL-2 protein required for the sustained growth of many cancers. Recently a highly specific MCL-1-inhibitor, S63845, showing 6-fold higher affinity to human compared to mouse MCL-1 has been described. To accurately test efficacy and tolerability of this BH3 mimetic drug in pre-clinical cancer models, we developed a humanized Mcl-1 (huMcl-1) mouse in which MCL-1 was replaced with its human homologue. HuMcl-1 mice are phenotypically indistinguishable from wild-type mice but are more sensitive to MCL-1 inhibition. Importantly, non-transformed cells and lymphomas from huMcl-1;Eμ-Myc mice are more sensitive to S63845 in vitro than their control counterparts. When huMcl-1;Eμ-Myc lymphoma cells are transplanted into huMcl-1 mice, treatment with S63845 alone or alongside cyclophosphamide leads to long-term remission in ~60% or almost 100% of mice, respectively. These results demonstrate the potential of our huMCL-1 mouse model to test MCL-1 inhibitors, allowing precise predictions of efficacy and tolerability for clinical translation.

Endocrinology ◽  
2012 ◽  
Vol 153 (9) ◽  
pp. 4181-4191 ◽  
Author(s):  
Brian J. DeBosch ◽  
Maggie Chi ◽  
Kelle H. Moley

Enterocyte fructose absorption is a tightly regulated process that precedes the deleterious effects of excess dietary fructose in mammals. Glucose transporter (GLUT)8 is a glucose/fructose transporter previously shown to be expressed in murine intestine. The in vivo function of GLUT8, however, remains unclear. Here, we demonstrate enhanced fructose-induced fructose transport in both in vitro and in vivo models of enterocyte GLUT8 deficiency. Fructose exposure stimulated [14C]-fructose uptake and decreased GLUT8 protein abundance in Caco2 colonocytes, whereas direct short hairpin RNA-mediated GLUT8 knockdown also stimulated fructose uptake. To assess GLUT8 function in vivo, we generated GLUT8-deficient (GLUT8KO) mice. GLUT8KO mice exhibited significantly greater jejunal fructose uptake at baseline and after high-fructose diet (HFrD) feeding vs. wild-type mice. Strikingly, long-term HFrD feeding in GLUT8KO mice exacerbated fructose-induced increases in blood pressure, serum insulin, low-density lipoprotein and total cholesterol vs. wild-type controls. Enhanced fructose uptake paralleled with increased abundance of the fructose and glucose transporter, GLUT12, in HFrD-fed GLUT8KO mouse enterocytes and in Caco2 cultures exposed to high-fructose medium. We conclude that GLUT8 regulates enterocyte fructose transport by regulating GLUT12, and that disrupted GLUT8 function has deleterious long-term metabolic sequelae. GLUT8 may thus represent a modifiable target in the prevention and treatment of malnutrition or the metabolic syndrome.


2021 ◽  
Author(s):  
Fatima Amanat ◽  
Shirin Strohmeier ◽  
Wen-Hsin Lee ◽  
Sandhya Bangaru ◽  
Andrew B Ward ◽  
...  

After first emerging in December 2019 in China, severe acute respiratory syndrome 2 (SARS-CoV-2) has since caused a pandemic leading to millions of infections and deaths worldwide. Vaccines have been developed and authorized but supply of these vaccines is currently limited. With new variants of the virus now emerging and spreading globally, it is essential to develop therapeutics that are broadly protective and bind conserved epitopes in the receptor binding domain (RBD) or the whole spike of SARS-CoV-2. In this study, we have generated mouse monoclonal antibodies (mAbs) against different epitopes on the RBD and assessed binding and neutralization against authentic SARS-CoV-2. We have demonstrated that antibodies with neutralizing activity, but not non-neutralizing antibodies, lower viral titers in the lungs when administered in a prophylactic setting in vivo in a mouse challenge model. In addition, most of the mAbs cross-neutralize the B.1.351 as well as the B.1.1.7 variants in vitro.


Author(s):  
Wanbo Tang ◽  
Jian He ◽  
Tao Huang ◽  
Zhijie Bai ◽  
Chaojie Wang ◽  
...  

In the aorta-gonad-mesonephros (AGM) region of mouse embryos, pre-hematopoietic stem cells (pre-HSCs) are generated from rare and specialized hemogenic endothelial cells (HECs) via endothelial-to-hematopoietic transition, followed by maturation into bona fide hematopoietic stem cells (HSCs). As HECs also generate a lot of hematopoietic progenitors not fated to HSCs, powerful tools that are pre-HSC/HSC-specific become urgently critical. Here, using the gene knockin strategy, we firstly developed an Hlf-tdTomato reporter mouse model and detected Hlf-tdTomato expression exclusively in the hematopoietic cells including part of the immunophenotypic CD45– and CD45+ pre-HSCs in the embryonic day (E) 10.5 AGM region. By in vitro co-culture together with long-term transplantation assay stringent for HSC precursor identification, we further revealed that unlike the CD45– counterpart in which both Hlf-tdTomato-positive and negative sub-populations harbored HSC competence, the CD45+ E10.5 pre-HSCs existed exclusively in Hlf-tdTomato-positive cells. The result indicates that the cells should gain the expression of Hlf prior to or together with CD45 to give rise to functional HSCs. Furthermore, we constructed a novel Hlf-CreER mouse model and performed time-restricted genetic lineage tracing by a single dose induction at E9.5. We observed the labeling in E11.5 AGM precursors and their contribution to the immunophenotypic HSCs in fetal liver (FL). Importantly, these Hlf-labeled early cells contributed to and retained the size of the HSC pool in the bone marrow (BM), which continuously differentiated to maintain a balanced and long-term multi-lineage hematopoiesis in the adult. Therefore, we provided another valuable mouse model to specifically trace the fate of emerging HSCs during development.


2021 ◽  
Author(s):  
Anna Vazquez-Oliver ◽  
Silvia Perez-Garcia ◽  
Nieves Pizarro ◽  
Laura Molina-Porcel ◽  
Rafael de la Torre ◽  
...  

Intellectual disability is the most prevalent and limiting hallmark of Down syndrome (DS), without any pharmacological treatment available. Neurodegeneration and neuroinflammation are relevant neurological features of DS reaching to early development of Alzheimer s disease. Preclinical evidence suggests that the endocannabinoid system, an important neuromodulator on cognition and neuroinflammation, could act as beneficial target in DS. Indeed, cannabinoid type-1 receptor (CB1R) activity was enhanced in the hippocampus of young-adult trisomic Ts65Dn mice, a well-characterized surrogate model of DS. In previous studies, inhibition of CB1R, was able to restore key neurological deficits in this mouse model. To determine the possible clinical relevance of this target, it is mandatory to evaluate the long-term consequences of attenuated CB1R activity and to minimize the possible side-effects associated to this mechanism. We found that CB1R expression was significantly enhanced in the hippocampus brains of aged DS subjects. Similarly, middle-aged trisomic mice showed enhanced CB1R expression. Long-term oral administration of a low dose of the CB1R specific antagonist rimonabant was administered to male and female Ts65Dn trisomic and wild-type mice from the time of weaning to 10 months, an age when signs of neurodegeneration have been described in the model. CB1R inhibition resulted in significant cognitive improvement in novel object-recognition memory in trisomic male and female mice, reaching a similar performance to that of wild-type littermates. Interestingly, this long-term rimonabant treatment modify locomotor activity, anxiety-like behavior, body weight or survival rates. Brain analysis at 10 months of age revealed noradrenergic and cholinergic neurodegeneration signs in trisomic mice that were not modified by the treatment, although the alterations in hippocampal microglia morphology shown by vehicle-treated trisomic mice was normalized in trisomic mice exposed to rimonabant. Altogether, our results demonstrate a sustained pro-cognitive effect of CB1R inhibition at doses that do not produce major side effects that could be associated to an anti-inflammatory action, suggesting a potential interest in this target of to preserve cognitive functionality in DS.


Author(s):  
Alice H. Huang ◽  
Robert L. Mauck

Articular cartilage lines the surfaces of joints and transmits the forces arising from locomotion. The poor ability of cartilage to self-repair has motivated efforts to engineer replacements that recapitulate this load-bearing function. While chondrocyte-laden constructs have been generated with near-native mechanical properties, limitations in chondrocyte availability may preclude their clinical use. Therefore, mesenchymal stem cells (MSCs), which can undergo chondrogenesis in 3D culture, have emerged as a promising alternative [1]. However, although MSCs deposit a cartilaginous matrix, mechanical and biochemical properties are lower than those achieved with chondrocytes [1, 2]. Using microarray analysis, we recently showed that limitations in functional MSC chondrogenesis may stem from incomplete or incorrect molecular induction; molecular differences were observed between donor-matched differentiated chondrocytes and newly differentiated MSCs over 8 weeks of culture [2]. While some genes remained consistently low in MSCs compared to chondrocytes, others gradually increased with time, approaching chondrocyte levels by 8 weeks. As these molecules may underlie the functional disparity between chondrocytes and MSCs, we hypothesized that longer culture durations may improve MSC-seeded construct properties and chondrogenesis. To test this hypothesis, we characterized the evolution of functional properties of MSC- and chondrocyte-seeded constructs over 4 months of in vitro culture in pro-chondrogenic medium.


1993 ◽  
Vol 293 (1) ◽  
pp. 181-185 ◽  
Author(s):  
N J Watkins ◽  
A K Campbell

cDNA coding for the Ca(2+)-activated photoprotein aequorin from the jellyfish Aequorea victoria has been engineered to investigate the role of the C-terminal proline residue in bioluminescence. Recombinant aequorin proteins were synthesized by PCR followed by in vitro transcription/translation, and characterized by specific activity, stability, and affinity for coelenterazine. The C-terminal proline residue of aequorin was shown to be essential for the long-term stability of the bound coelenterazine. Aequorin minus proline had only 1% of the specific activity of the wild-type after 2 h, and was virtually inactive after 18 h. The instability of this variant was further demonstrated by re-activating with a coelenterazine analogue (epsilon-coelenterazine), where maximum reactivation was reached in 15 min, and the luminescent activity was almost completely abolished within 3 h. Replacement of the C-terminal proline residue with histidine or glutamic acid decreased the specific activity to 10 and 19% of that of the wild-type respectively. However these variants were also unstable, having t1/2 values of 2.4 h and 2.3 h respectively. Enhancement of the Ca(2+)-independent light emission when proline was replaced by histidine confirmed the stabilizing role of the C-terminal proline. No significant effect of removal of the C-terminal proline was detected on the affinity for coelenterazine.


2014 ◽  
Vol 59 (1) ◽  
pp. 226-232 ◽  
Author(s):  
Brian G. Gentry ◽  
Quang Phan ◽  
Ellie D. Hall ◽  
Julie M. Breitenbach ◽  
Katherine Z. Borysko ◽  
...  

ABSTRACTHuman cytomegalovirus (HCMV) infection can cause severe illnesses, including encephalopathy and mental retardation, in immunocompromised and immunologically immature patients. Current pharmacotherapies for treating systemic HCMV infections include ganciclovir, cidofovir, and foscarnet. However, long-term administration of these agents can result in serious adverse effects (myelosuppression and/or nephrotoxicity) and the development of viral strains with reduced susceptibility to drugs. The deoxyribosylindole (indole) nucleosides demonstrate a 20-fold greater activityin vitro(the drug concentration at which 50% of the number of plaques was reduced with the presence of drug compared to the number in the absence of drug [EC50] = 0.34 μM) than ganciclovir (EC50= 7.4 μM) without any observed increase in cytotoxicity. Based on structural similarity to the benzimidazole nucleosides, we hypothesize that the indole nucleosides target the HCMV terminase, an enzyme responsible for packaging viral DNA into capsids and cleaving the DNA into genome-length units. To test this hypothesis, an indole nucleoside-resistant HCMV strain was isolated, the open reading frames of the genes that encode the viral terminase were sequenced, and a G766C mutation in exon 1 ofUL89was identified; this mutation resulted in an E256Q change in the amino acid sequence of the corresponding protein. An HCMV wild-type strain, engineered with this mutation to confirm resistance, demonstrated an 18-fold decrease in susceptibility to the indole nucleosides (EC50= 3.1 ± 0.7 μM) compared to that of wild-type virus (EC50= 0.17 ± 0.04 μM). Interestingly, this mutation did not confer resistance to the benzimidazole nucleosides (EC50for wild-type HCMV = 0.25 ± 0.04 μM, EC50for HCMV pUL89 E256Q = 0.23 ± 0.04 μM). We conclude, therefore, that the G766C mutation that results in the E256Q substitution is unique for indole nucleoside resistance and distinct from previously discovered substitutions that confer both indole and benzimidazole nucleoside resistance (D344E and A355T).


2004 ◽  
Vol 48 (1) ◽  
pp. 80-85 ◽  
Author(s):  
E. Azoulay-Dupuis ◽  
J. Mohler ◽  
J. P. Bédos

ABSTRACT The efficacy of BB-83698, a novel potent peptide deformylase inhibitor, was evaluated in a mouse model of acute pneumonia. The Streptococcus pneumoniae isolates tested included four virulent strains (one penicillin-susceptible wild-type strain, one macrolide-resistant strain, and two quinolone-resistant mutants [a mutant carrying mutations in ParC and GyrA and an efflux mutant] isogenic to the wild type) and two poorly virulent penicillin-resistant strains. Pneumonia was induced by intratracheal inoculation of 105 CFU (virulent strains) into immunocompetent mice or 107 CFU (less virulent strains) into leukopenic mice. Animals received three or six subcutaneous injections of antibiotics at 12- or 24-h intervals, with antibiotic treatment initiated at 3, 6, 12, or 18 h postinfection (p.i.). BB-83698 showed potent in vitro activity against all strains (MICs, 0.06 to 0.25 μg/ml). In the in vivo model, all control animals died within 2 to 5 days of infection. BB-83698 (80 mg/kg of body weight twice daily or 160 mg/kg once daily) protected 70 to 100% of the animals, as measured 10 days p.i., regardless of the preexisting resistance mechanisms. In contrast, the survival rates for animals treated with the comparator antibiotics were 30% for animals treated with erythromycin (100 mg/kg) and infected with the macrolide-resistant strain, 34% for animals treated with amoxicillin (200 mg/kg every 8 h) and infected with the penicillin-resistant strain, and 0 and 78% for animals treated with ciprofloxacin (250 mg/kg) and infected with the ParC and GyrA mutant and the efflux mutant, respectively. At 80 mg/kg, BB-83698 generated a peak concentration in lung tissue of 61.9 μg/ml within 1 h and areas under the concentration-times curves of 57.4 and 229.4 μg · h/ml for plasma and lung tissue, respectively. The emergence of S. pneumoniae isolates with reduced susceptibilities to BB-83698 was not observed following treatment with a suboptimal dosing regimen. In conclusion, the potent in vitro activity of BB-83698 against S. pneumoniae, including resistant strains, translates into good in vivo efficacy in a mouse pneumonia model.


Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 641-641 ◽  
Author(s):  
Suzanne Trudel ◽  
Zhi Hua Li ◽  
Ellen Wei ◽  
Marion Wiesmann ◽  
Katherine Rendahl ◽  
...  

Abstract The t(4;14) translocation that occurs uniquely in a subset (15%) of multiple myeloma (MM) patients results in the ectopic expression of the receptor tyrosine kinase, Fibroblast Growth Factor Receptor3 (FGFR3). Wild-type FGFR3 induces proliferative signals in myeloma cells and appears to be weakly transforming in a hematopoeitic mouse model. The subsequent acquisition of FGFR3 activating mutations in some MM is associated with disease progression and is strongly transforming in several experimental models. The clinical impact of t(4;14) translocations has been demonstrated in several retrospective studies each reporting a marked reduction in overall survival. We have previously shown that inhibition of activated FGFR3 causes morphologic differentiation followed by apoptosis of FGFR3 expressing MM cell lines, validating activated FGFR3 as a therapeutic target in t(4;14) MM and encouraging the clinical development of FGFR3 inhibitors for the treatment of these poor-prognosis patients. CHIR258 is a small molecule kinase inhibitor that targets Class III–V RTKs and inhibits FGFR3 with an IC50 of 5 nM in an in vitro kinase assay. Potent anti-tumor and anti-angiogenic activity has been demonstrated in vitro and in vivo. We employed the IL-6 dependent cell line, B9 that has been engineered to express wild-type FGFR3 or active mutants of FGFR3 (Y373C, K650E, G384D and 807C), to screen CHIR258 for activity against FGFR3. CHIR258 differentially inhibited FGF-mediated growth of B9 expressing wild-type and mutant receptors found in MM, with an IC50 of 25 nM and 80 nM respectively as determined by MTT proliferation assay. Growth of these cells could be rescued by IL-6 demonstrating selectivity of CHIR258 for FGFR3. We then confirmed the activity of CHIR258 against FGFR3 expressing myeloma cells. CHIR258 inhibited the viability of FGFR3 expressing KMS11 (Y373C), KMS18 (G384D) and OPM-2 (K650E) cell lines with an IC50 of 100 nM, 250 nM and 80 nM, respectively. Importantly, inhibition with CHIR258 was still observed in the presence of IL-6, a potent growth factors for MM cells. U266 cells, which lack FGFR3 expression, displayed minimal growth inhibition demonstrating that at effective concentrations, CHIR258 exhibits minimal nonspecific cytotoxicity on MM cells. Further characterization of this finding demonstrated that inhibition of cell growth corresponded to G0/G1 cell cycle arrest and dose-dependent inhibition of downstream ERK phosphorylation. In responsive cell lines, CHIR258 induced apoptosis via caspase 3. In vitro combination analysis of CHIR258 and dexamethasone applied simultaneously to KMS11 cells indicated a synergistic interaction. In vivo studies demonstrated that CHIR258 induced tumor regression and inhibited growth of FGFR3 tumors in a plasmacytoma xenograft mouse model. Finally, CHIR258 produced cytotoxic responses in 4/5 primary myeloma samples derived from patients harboring a t(4;14) translocation. These data indicate that the small molecule inhibitor, CHIR258 potently inhibits FGFR3 and has activity against human MM cells setting the stage for a Phase I clinical trial of this compound in t(4;14) myeloma.


2006 ◽  
Vol 74 (2) ◽  
pp. 1360-1367 ◽  
Author(s):  
Laura Plant ◽  
Johanna Sundqvist ◽  
Susu Zughaier ◽  
Lena Lövkvist ◽  
David S. Stephens ◽  
...  

ABSTRACT Lipooligosaccharide (LOS) of Neisseria meningitidis has been implicated in meningococcal interaction with host epithelial cells and is a major factor contributing to the human proinflammatory response to meningococci. LOS mutants of the encapsulated N. meningitidis serogroup B strain NMB were used to further determine the importance of the LOS structure in in vitro adherence and invasion of human pharyngeal epithelial cells by meningococci and to study pathogenicity in a mouse (CD46 transgenic) model of meningococcal disease. The wild-type strain [NeuNAc-Galβ-GlcNAc-Galβ-Glcβ-Hep2 (GlcNAc, Glcα) 3-deoxy-d-manno-2-octulosonic acid (KDO2)-lipid A; 1,4′ bisphosphorylated], although poorly adherent, rapidly invaded an epithelial cell layer in vitro, survived and multiplied early in blood, reached the cerebrospinal fluid, and caused lethal disease in the mouse model. In contrast, the Hep2 (GlcNAc) KDO2-lipid A (pgm) mutant, which was highly adherent to cultured epithelial cells, caused significantly less bacteremia and mortality in the mouse model. The Hep2-KDO2-lipid A (rfaK) mutant was shown to be moderately adherent and to cause levels of bacteremia and mortality similar to those caused by the wild-type strain in the mouse model. The KDO2-lipid A (gmhB) mutant, which lacks the heptose disaccharide in the inner core of LOS, avidly attached to epithelial cells but was otherwise avirulent. Disease development correlated with expression of specific LOS structures and was associated with lower adherence but rapid meningococcal passage to and survival in the bloodstream, induction of proinflammatory cytokines, and the crossing of the blood-brain barrier. Taken together, the results of this study further define the importance of the LOS structure as a virulence component involved in multiple steps in the pathogenesis of N. meningitidis.


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