scholarly journals Mutant IDH is sufficient to initiate enchondromatosis in mice

2015 ◽  
Vol 112 (9) ◽  
pp. 2829-2834 ◽  
Author(s):  
Makoto Hirata ◽  
Masato Sasaki ◽  
Rob A. Cairns ◽  
Satoshi Inoue ◽  
Vijitha Puviindran ◽  
...  
Keyword(s):  
Enzymatic Activity ◽  
Growth Plate ◽  
Mutant Allele ◽  
Somatic Mutations ◽  
Expression Of Genes ◽  
Idh Mutations ◽  
Neonatal Stage ◽  
Cartilage Tumors ◽  
Tumor Types

Enchondromas are benign cartilage tumors and precursors to malignant chondrosarcomas. Somatic mutations in the isocitrate dehydrogenase genes (IDH1 and IDH2) are present in the majority of these tumor types. How these mutations cause enchondromas is unclear. Here, we identified the spectrum of IDH mutations in human enchondromas and chondrosarcomas and studied their effects in mice. A broad range of mutations was identified, including the previously unreported IDH1-R132Q mutation. These mutations harbored enzymatic activity to catalyze α-ketoglutarate to d-2-hydroxyglutarate (d-2HG). Mice expressing Idh1-R132Q in one allele in cells expressing type 2 collagen showed a disordered growth plate, with persistence of type X-expressing chondrocytes. Chondrocyte cell cultures from these animals or controls showed that there was an increase in proliferation and expression of genes characteristic of hypertrophic chondrocytes with expression of Idh1-R132Q or 2HG treatment. Col2a1-Cre;Idh1-R132Q mutant knock-in mice (mutant allele expressed in chondrocytes) did not survive after the neonatal stage. Col2a1-Cre/ERT2;Idh1-R132 mutant conditional knock-in mice, in which Cre was induced by tamoxifen after weaning, developed multiple enchondroma-like lesions. Taken together, these data show that mutant IDH or d-2HG causes persistence of chondrocytes, giving rise to rests of growth-plate cells that persist in the bone as enchondromas.

Mutant IDH is sufficient to initiate enchondromatosis in mice

2020 ◽  
Author(s):  
Lungwani Muungo
Keyword(s):  
Enzymatic Activity ◽  
Cell Cultures ◽  
Mutant Allele ◽  
Somatic Mutations ◽  
Hypertrophic Chondrocytes ◽  
Idh Mutations ◽  
Neonatal Stage ◽  
Cartilage Tumors ◽  
Tumor Types

Enchondromas are benign cartilage tumors and precursors tomalignant chondrosarcomas. Somatic mutations in the isocitratedehydrogenase genes (IDH1 and IDH2) are present in the majorityof these tumor types. How these mutations cause enchondromasis unclear. Here, we identified the spectrum of IDH mutations inhuman enchondromas and chondrosarcomas and studied theireffects in mice. A broad range of mutations was identified, includingthe previously unreported IDH1-R132Q mutation. These mutationsharbored enzymatic activity to catalyze α-ketoglutarate toD-2-hydroxyglutarate (D-2HG). Mice expressing Idh1-R132Q in oneallele in cells expressing type 2 collagen showed a disorderedgrowth plate, with persistence of type X-expressing chondrocytes.Chondrocyte cell cultures from these animals or controls showedthat there was an increase in proliferation and expression of genescharacteristic of hypertrophic chondrocytes with expression ofIdh1-R132Q or 2HG treatment. Col2a1-Cre;Idh1-R132Q mutantknock-in mice (mutant allele expressed in chondrocytes) did notsurvive after the neonatal stage. Col2a1-Cre/ERT2;Idh1-R132 mutantconditional knock-in mice, in which Cre was induced by tamoxifenafter weaning, developed multiple enchondroma-like lesions.Taken together, these data show that mutant IDH or D-2HG causespersistence of chondrocytes, giving rise to rests of growth-platecells that persist in the bone as enchondromas.

scholarly journals Conditional Deletion of Prolyl Hydroxylase Domain-Containing Protein 2 (Phd2) Gene Reveals Its Essential Role in Chondrocyte Function and Endochondral Bone Formation

Endocrinology ◽  
2016 ◽  
Vol 157 (1) ◽  
pp. 127-140 ◽  
Author(s):  
Shaohong Cheng ◽  
Weirong Xing ◽  
Sheila Pourteymoor ◽  
Jan Schulte ◽  
Subburaman Mohan
Keyword(s):  
Bone Formation ◽  
Growth Plate ◽  
Prolyl Hydroxylase ◽  
Conditional Knockout ◽  
Hypertrophic Chondrocytes ◽  
Endochondral Bone Formation ◽  
Bone Surface ◽  
Endochondral Bone ◽  
Prolyl Hydroxylase Domain

Abstract The hypoxic growth plate cartilage requires hypoxia-inducible factor (HIF)-mediated pathways to maintain chondrocyte survival and differentiation. HIF proteins are tightly regulated by prolyl hydroxylase domain-containing protein 2 (Phd2)-mediated proteosomal degradation. We conditionally disrupted the Phd2 gene in chondrocytes by crossing Phd2 floxed mice with type 2 collagen-α1-Cre transgenic mice and found massive increases (>50%) in the trabecular bone mass of long bones and lumbar vertebra of the Phd2 conditional knockout (cKO) mice caused by significant increases in trabecular number and thickness and reductions in trabecular separation. Cortical thickness and tissue mineral density at the femoral middiaphysis of the cKO mice were also significantly increased. Dynamic histomorphometric analyses revealed increased longitudinal length and osteoid surface per bone surface in the primary spongiosa of the cKO mice, suggesting elevated conversion rate from hypertrophic chondrocytes to mineralized bone matrix as well as increased bone formation in the primary spongiosa. In the secondary spongiosa, bone formation measured by mineralizing surface per bone surface and mineral apposition rate were not changed, but resorption was slightly reduced. Increases in the mRNA levels of SRY (sex determining region Y)-box 9, osterix (Osx), type 2 collagen, aggrecan, alkaline phosphatase, bone sialoprotein, vascular endothelial growth factor, erythropoietin, and glycolytic enzymes in the growth plate of cKO mice were detected by quantitative RT-PCR. Immunohistochemistry revealed an increased HIF-1α protein level in the hypertrophic chondrocytes of cKO mice. Infection of chondrocytes isolated from Phd2 floxed mice with adenoviral Cre resulted in similar gene expression patterns as observed in the cKO growth plate chondrocytes. Our findings indicate that Phd2 suppresses endochondral bone formation, in part, via HIF-dependent mechanisms in mice.

Somatic mutations in the neurofibromatosis type 2 gene in sporadic meningiomas

1995 ◽  
Vol 95 (3) ◽  
pp. 347-351 ◽  
Author(s):  
Laura Papi ◽  
Lucia Rosaria De Vitis ◽  
Francesca Vitelli ◽  
Enrico Montali ◽  
Umberto Bigozzi ◽  
...  
Keyword(s):  
Somatic Mutations ◽  
Neurofibromatosis Type ◽  
Neurofibromatosis Type 2

16. Physiological effects of IDH1 loss-of-function on Chondrocyte Differentiation through Hedgehog Pathway upregulation

2018 ◽  
Author(s):  
Cassie Tyson
Keyword(s):  
Developmental Stages ◽  
Hedgehog Pathway ◽  
Chondrocyte Differentiation ◽  
Loss Of Function ◽  
Wild Type ◽  
Phenotypic Analysis ◽  
Growth Plate Chondrocytes ◽  
Idh Mutations ◽  
Cartilage Tumors ◽  
Deficient Mice

Cartilage tumors are the most common and terminal primary neoplasms in bone. Physiologically, bones formed through endochondral ossification are regulated by the Hedgehog pathway and Parathyroid hormone-like hormone feedback loop. The upregulation of the infamous Hedgehog pathway has been demonstrated in several non-cartilaginous neoplasms. Recently, frequent mutational events of isocitrate dehydrogenase1 (IDH1) were identified in cartilage tumors. In other neoplasms, IDH mutations produces an oncometabolite that can promote HIF1a activation, contributing to tumorigenesis. Currently, the role of IDH1 mutations in cartilage tumors remain unknown. Investigating the physiological aspect of IDH1proves useful in identifying novel therapeutic targets for cartilage tumors. IDH1 deficient and wild-type littermates, were harvested for forelimbs and hindlimbs at various developmental stages for phenotypic analysis via hematoxylin and eosin staining. Histological analysis demonstrated IDH1 homozygous deficient mice at embryonic stages exhibited dwarfism and an elongated layer of hypertrophic chondrocytes. This was verified via immunohistochemistry Type 10 Collagen staining and Quantitative PCR (qPCR) using the chondrocyte terminal differentiation marker Col10a1. Whole skeletons of IDH1 deficient mice were subjected to skeletal double staining which demonstrated delayed mineralization of underdeveloped IDH1 deficient mice contrasted with wild-type littermates. qPCR was performed to examine the status of chondrocyte differentiation through the Hedgehog pathway in cultured primarymouse growth plate chondrocytes. Interestingly, IDH1 deficient non-neoplastic cells revealed significant upregulation of Hedgehog target molecules in IDH1 deficient chondrocytes. As a result, the loss-offunction of IDH1 was identified as a potential impairment of chondrocyte differentiation and a factor towards chondrocyte tumorgenisis.

scholarly journals VITAMIN D RECEPTOR GENE POLYMORPHISMS AND HAPLOTYPE ANALYSIS IN TYPE 2 DIABETES MELLITUS PATIENTS FROM NORTH INDIA

2017 ◽  
Vol 10 (10) ◽  
pp. 248
Author(s):  
Nancy Taneja ◽  
Rajesh Khadgawat ◽  
Shalini Mani
Keyword(s):  
Diabetes Mellitus ◽  
Type 2 Diabetes ◽  
Vitamin D ◽  
Type 2 Diabetes Mellitus ◽  
Vitamin D Receptor ◽  
Mutant Allele ◽  
Haplotype Analysis ◽  
Vdr Gene ◽  
Vdr Polymorphisms

  Objective: Vitamin D receptor (VDR) mediated Vitamin D signaling is important for expression of insulin gene and glucose transporters, which help in glucose uptake by cells. Current evidence suggests that four common polymorphisms (FokI, BsmI, ApaI, TaqI) of VDR gene are associated with Type 2 diabetes mellitus (T2DM) in different populations. However, there is a scarcity of data on VDR polymorphisms from Indian population.Methods: In the current study, total genomic DNA was isolated from 100 well-characterized T2DM patients and 100 healthy controls. We investigated the prevalence of FokI and ApaI polymorphisms in VDR gene of these patients by polymerase chain reaction-restriction fragment length polymorphism-based method. Taking help of our previous published data on TaqI and BsmI polymorphisms in same patients, the haplotype study was also conducted. Statistical analysis of data was performed using SPSS 21.0 software. Haplotype and linkage disequilibrium analysis was performed by Haploview software.Results: Both the wild (TT) and mutant (CC) genotype of FokI polymorphism showed a significant difference between patients and controls (p<0.001 and p<0.001, respectively). The frequency of mutant allele (C) was also significantly higher in T2DM patients than the controls (p<0.001). In case of ApaI, frequency of wild (GG) and mutant (CC) genotype was significantly different in patients and controls (p=0.017 and p=0.034). As per haplotype analysis, the CACT haplotype was predicted to be of significance in patients and consists of mutant alleles of three polymorphisms (FokI, BsmI, ApaI). Conclusion: Our study supports the association of FokI and ApaI polymorphism in T2DM. The haplotype analysis also indicates that the combinations of mutant allele of different VDR polymorphisms are probably responsible for increased susceptibility of these individuals toward T2DM.

scholarly journals Using the Minor Variant Finder software to identify and quantify the allelic burden level of somatic mutations in oncohematologic diseases

2020 ◽  
Vol 15 (2) ◽  
pp. 85-91
Author(s):  
T. N. Subbotina ◽  
I. E. Maslyukova ◽  
A. A. Faleeva ◽  
P. A. Nikolaeva ◽  
A. S. Khazieva ◽  
...  
Keyword(s):  
Mutant Allele ◽  
Sanger Sequencing ◽  
Quantitative Assessment ◽  
Somatic Mutations ◽  
Myeloproliferative Neoplasms ◽  
Mutant Gene ◽  
Positive Sample ◽  
Allele Burden ◽  
Minor Variant ◽  
Allelic Burden

Background. There are problems related to both quantitative assessment of an allele burden level of a mutant gene and interpretation of results in DNA samples with the burden level of the mutant allele less than 15–20 %, when using Sanger sequencing for analyzing somatic mutations. Applied Biosystems (USA) has developed new software Minor Variant Finder, which allows determining mutations with the allele burden level from 5 %.The objective: to determine the allele burden level and identification of minor variants of somatic mutations in the ASXL1, JAK2 genes and BCR-ABL oncogene using Minor Variant Finder software in patients with myeloproliferative neoplasms.Materials and methods. The level of mutant allele burden for 15 patients with myeloproliferative neoplasms was determined by the identified mutations using the Minor Variant Finder software, after analysis of point somatic mutations in the ASXL1, JAK2 genes and BCR-ABL oncogene by Sanger sequencing.Results. The allele burden level in all 5 ASXL1-positive samples and BCR-ABL-positive sample was determined as higher than 20 % using the Minor Variant Finder software. The allele burden level in 2 cases was higher than 20 % and in 7 cases lower than 20 %, when we analyzed 9 JAK2-positive samples.Conclusion. Minor Variant Finder software can be used to estimate the allele burden level and to identify minor variants of somatic mutations in the ASXL, JAK2 and BCR-ABL genes.

scholarly journals Oral DhHP-6 for the Treatment of Type 2 Diabetes Mellitus

2019 ◽  
Vol 20 (6) ◽  
pp. 1517 ◽  
Author(s):  
Kai Wang ◽  
Yu Su ◽  
Yuting Liang ◽  
Yanhui Song ◽  
Liping Wang
Keyword(s):  
Diabetes Mellitus ◽  
Type 2 Diabetes ◽  
Type 2 Diabetes Mellitus ◽  
Blood Glucose ◽  
Enzymatic Activity ◽  
Glucose Levels ◽  
Blood Glucose Levels

Type 2 diabetes mellitus (T2DM) is associated with pancreatic β-cell dysfunction which can be induced by oxidative stress. Deuterohemin-βAla-His-Thr-Val-Glu-Lys (DhHP-6) is a microperoxidase mimetic that can scavenge reactive oxygen species (ROS) in vivo. In our previous studies, we demonstrated an increased stability of linear peptides upon their covalent attachment to porphyrins. In this study, we assessed the utility of DhHP-6 as an oral anti-diabetic drug in vitro and in vivo. DhHP-6 showed high resistance to proteolytic degradation in vitro and in vivo. The degraded DhHP-6 product in gastrointestinal (GI) fluid retained the enzymatic activity of DhHP-6, but displayed a higher permeability coefficient. DhHP-6 protected against the cell damage induced by H2O2 and promoted insulin secretion in INS-1 cells. In the T2DM model, DhHP-6 reduced blood glucose levels and facilitated the recovery of blood lipid disorders. DhHP-6 also mitigated both insulin resistance and glucose tolerance. Most importantly, DhHP-6 promoted the recovery of damaged pancreas islets. These findings suggest that DhHP-6 in physiological environments has high stability against enzymatic degradation and maintains enzymatic activity. As DhHP-6 lowered the fasting blood glucose levels of T2DM mice, it thus represents a promising candidate for oral administration and clinical therapy.

scholarly journals STK11 (LKB1) missense somatic mutant isoforms promote tumor growth, motility and inflammation

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Paula Granado-Martínez ◽  
Sara Garcia-Ortega ◽  
Elena González-Sánchez ◽  
Kimberley McGrail ◽  
Rafael Selgas ◽  
...  
Keyword(s):  
Tumor Growth ◽  
Somatic Mutations ◽  
Human Cancer ◽  
Tumor Biology ◽  
Missense Mutations ◽  
Expression Of Genes ◽  
Promote Tumor Growth ◽  
Genes Encoding ◽  
Differential Gene ◽  
Somatic Mutant

AbstractElucidating the contribution of somatic mutations to cancer is essential for personalized medicine. STK11 (LKB1) appears to be inactivated in human cancer. However, somatic missense mutations also occur, and the role/s of these alterations to this disease remain unknown. Here, we investigated the contribution of four missense LKB1 somatic mutations in tumor biology. Three out of the four mutants lost their tumor suppressor capabilities and showed deficient kinase activity. The remaining mutant retained the enzymatic activity of wild type LKB1, but induced increased cell motility. Mechanistically, LKB1 mutants resulted in differential gene expression of genes encoding vesicle trafficking regulating molecules, adhesion molecules and cytokines. The differentially regulated genes correlated with protein networks identified through comparative secretome analysis. Notably, three mutant isoforms promoted tumor growth, and one induced inflammation-like features together with dysregulated levels of cytokines. These findings uncover oncogenic roles of LKB1 somatic mutations, and will aid in further understanding their contributions to cancer development and progression.

Sign in / Sign up

Export Citation Format

Share Document