Mutation analyses of the NFAT1 gene in chondrosarcomas and enchondromas

Genetic susceptibility to bone and soft tissue sarcomas: a field synopsis and meta-analysis

Background

The genetic architecture of bone and soft tissue sarcomas susceptibility is yet to be elucidated. We aimed to comprehensively collect and meta-analyze the current knowledge on genetic susceptibility in these rare tumors.

Methods

We conducted a systematic review and meta-analysis of the evidence on the association between DNA variation and risk of developing sarcomas through searching PubMed, The Cochrane Library, Scopus and Web of Science databases. To evaluate result credibility, summary evidence was graded according to the Venice criteria and false positive report probability (FPRP) was calculated to further validate result noteworthiness. Integrative analysis of genetic and eQTL (expression quantitative trait locus) data was coupled with network and pathway analysis to explore the hypothesis that specific cell functions are involved in sarcoma predisposition.

Results

We retrieved 90 eligible studies comprising 47,796 subjects (cases: 14,358, 30%) and investigating 1,126 polymorphisms involving 320 distinct genes. Meta-analysis identified 55 single nucleotide polymorphisms (SNPs) significantly associated with disease risk with a high (N=9), moderate (N=38) and low (N=8) level of evidence, findings being classified as noteworthy basically only when the level of evidence was high. The estimated joint population attributable risk for three independent SNPs (rs11599754 of ZNF365/EGR2, rs231775 of CTLA4, and rs454006 of PRKCG) was 37.2%. We also identified 53 SNPs significantly associated with sarcoma risk based on single studies.Pathway analysis enabled us to propose that sarcoma predisposition might be linked especially to germline variation of genes whose products are involved in the function of the DNA repair machinery.

Conclusions

We built the first knowledgebase on the evidence linking DNA variation to sarcomas susceptibility, which can be used to generate mechanistic hypotheses and inform future studies in this field of oncology.

Nerve Regeneration Promoted in a Tube with Vascularity Containing Bone Marrow-Derived Cells

Bone marrow-derived cells (BMCs) are multipotent cells that have the potential to differentiate into bone, cartilage, fat, muscle, or neuronal lineages such as neurons and glial cells. A silicone tube model containing reverse-pedicled sural vessels was created in the sciatic nerves of Lewis rats. About 1 × 107 BMCs, removed from the bone marrow of synergetic rat femurs and cultured in vitro, were transplanted into the 15-mm-long chambers of the silicone tubes. Nerve regeneration in vessel-containing tubes that had received BMCs was significantly greater at 12 and 24 weeks after surgery than in tubes that did not receive cells. Transplantation of fibroblasts instead of BMCs into the vessel-containing tube resulted in reduced axonal regeneration, which was inferior to regeneration in the vessel-containing tube that did not receive cells. Polymerase chain reaction (PCR) studies revealed that in vessel-containing tubes containing transplanted BMCs, about 29% of cells in the regenerated nerve originated from BMCs. Cells identified by in situ hybridization and PKH26 prelabeling as being of BMC origin stained positively for S100 and GFAP. Transplanted BMCs differentiated into cells with phenotypes similar to those of Schwann cells under the influence of neurochemical factors and survived by obtaining nutrients from vessels that had been preinserted into the tube. They thus functioned similarly to Schwann cells, promoting nerve regeneration.

Association of the Smad3 and NFATc2 gene polymorphisms and their serum levels with susceptibility to rheumatoid arthritis in Polish cohorts

One among many factors involved in induction of rheumatoid arthritis (RA) are T cells, the differentiation of which depends upon a unique combination of stimulants and subsequent activation of diverse transcription factors. The aim of this study was to identify polymorphic variants in Smad3 and NFATc2 genes and their possible association with susceptibility to and severity of RA. A total of 272 RA patients, 321 for Smad3 and 304 for nuclear factor of activated T cells (NFAT)c2 healthy individuals, were examined for rs6494629 C/T and rs2289263 T/G Smad3 and rs880324 NFATc2 gene polymorphisms using the polymerase chain reaction-fragment length polymorphism (PCR-RFLP) method and TaqMan single nucleotide polymorphism (SNP) genotyping assay, respectively. Serum Smad3 and NFATc2 levels in RA patients and controls were measured by enzyme-linked immunosorbent assay (ELISA). The rs6494629 C/T Smad3 gene polymorphism under the recessive (TT versus CC+CT) and over-dominant (CC+TT versus CT) models were associated with RA (P=0.014 and P=0.008, respectively). Smad3 rs2289263 T/G revealed differences in the case-control distribution in co-dominant, recessive and over-dominant models (P=0.037, P=0.010, P=0.034). Overall, rs6494629 C/T and rs2289263 T/G Smad3 gene polymorphisms were in a weak linkage disequilibrium (LD) with D'=0.116 and r(2)=0.004. After Bonferroni correction, the genotype-phenotype analysis showed no significant correlation of the Smad3 rs6494629 C/T and rs2289263 T/G and NFATc2 rs2289263 TT polymorphisms with disease activity, joint damage and extra-articular manifestation in RA patients. Serum Smad3 and NFATc2 levels were significantly higher in RA patients than in control groups (both P=0 0000). The present findings indicated that Smad3 genetic polymorphisms may be associated with the susceptibility to RA in the Polish population.

Role of nuclear factor of activated T cells 1 in the pathogenesis of osteoarthritis

Osteoarthritis (OA) is the most common form of joint disease in middle-aged individuals and the elderly. Previous studies have shown that the overexpression of matrix-degrading proteinases and proinflammatory cytokines is associated with the degradation of osteoarthritic cartilage. However, the transcription factors involved remain unclear. The present study aimed to determine the expression levels of nuclear factor of activated T cells 1 (NFAT1), interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) in patients with OA, and to validate the role of NFAT1 in the pathogenesis of OA. The expression levels of NFAT1, IL-1β and TNF-α in chondrocytes in the cartilage of patients with OA and healthy individuals were evaluated using western blot analysis. A luciferase reporter assay was performed to determine the activity of NFAT1 in primary human chondrocytes that were transfected with pNFAT1-luc plasmid and stimulated by IL-1β. An enzyme-linked immunosorbent assay was performed to detect the levels of TNF-α, matrix metalloproteinase (MMP)-1, MMP-3 and MMP-9 in the supernatant of cultured chondrocytes in which the NFAT1 was silenced. The expression levels of NFAT1, IL-1β and TNF-α in the cartilage of patients with OA were higher than those of the controls. IL-1β induced the expression of NFAT1 in primary chondrocytes. The expression levels of TNF-α, MMP-1, -3 and -9 promoted by IL-1β were decreased in NFAT1-silenced chondrocytes. In conclusion, NFAT1 may be important in the pathogenesis of OA and calcineurin-NFAT inhibitors may be potential effective agents for the treatment of OA.

Genetic polymorphisms of the transcription factor NFATc4 and development of new-onset diabetes after transplantation in Hispanic kidney transplant recipients

Transcription factors of the nuclear factor of activated T cells (NFAT) family regulate both immune activation and insulin production. Calcineurin inhibitors (CNIs) target NFAT activation. Hence, CNIs not only prevent organ transplant rejection but also contribute to the development of new-onset diabetes after transplantation (NODAT). Given individual variation in the susceptibility to NODAT, we hypothesized that polymorphisms in the cytoplasmic NFAT (NFATc)4 gene, which is expressed in pancreatic islets, may be associated with NODAT. Haplotype-tagging single-nucleotide polymorphisms (SNPs) of the NFATc4 gene were genotyped in Hispanic renal transplant patients. Cumulative incidences of NODAT were compared between recipients of different NFATc4 genotypes and haplotypes. The Cox proportional hazard model was used to examine risks for NODAT. Nongenetic and genetic characteristics were included in the multivariate risk model. The SNP (rs10141896) T allele was associated with a lower cumulative incidence of NODAT (P=0.02). This is a tagging SNP for one of the five dominant NFATc4 haplotypes, T-T-T-T-G, and CNI-treated recipients with this haplotype had a reduced adjusted risk for NODAT (hazard ratio: 0.45; 95% confidence interval: 0.19-1.01). Conversely, patients homozygous for the C-C-C-G-G haplotype were at an increased risk (hazard ratio: 2.13; 95% confidence interval: 1.01-4.46) for NODAT in subanalysis. Of the nongenetic factors, use of tacrolimus, sirolimus, and older age were associated with increased risk for NODAT. Polymorphisms in the NFATc4 gene may confer certain protection or predisposition for NODAT.

Nfat1 regulates adult articular chondrocyte function through its age-dependent expression mediated by epigenetic histone methylation

The development of disease-modifying pharmacologic therapy for osteoarthritis (OA) currently faces major obstacles largely because the regulatory mechanisms for the function of adult articular chondrocytes remain unclear. We previously demonstrated that lack of Nfat1, one of the nuclear factor of activated T cells (NFAT) transcription factors, causes OA-like changes in adult mice. This study aimed to identify whether Nfat1 specifically regulates adult articular chondrocyte function and its age-dependent regulatory mechanism using both Nfat1-deficient and wild-type mice. Deletion of Nfat1 did not induce OA-like articular chondrocyte dysfunction (e.g., overexpression of proinflammatory cytokines and matrix-degrading proteinases) until the adult stage. RNAi-mediated Nfat1 knockdown caused dysfunction of wild-type adult articular chondrocytes. Nfat1 expression in wild-type articular chondrocytes was low in the embryonic but high in the adult stage. Chromatin immunoprecipitation assays demonstrated that an increase in Nfat1 expression in articular chondrocytes was associated with increased H3K4me2 (a histone modification linked to transcriptional activation), whereas a decrease in Nfat1 expression in articular chondrocytes was correlated with increased H3K9me2 (a histone modification linked to transcriptional repression). Knockdown of lysine-specific demethylase-1 (Lsd1) in embryonic articular chondrocytes upregulated Nfat1 expression concomitant with increased H3K4me2 at the Nfat1 promoter. Knockdown of Jmjc-containing histone demethylase-2a (Jhdm2a) in 6-month articular chondrocytes downregulated Nfat1 expression concomitant with increased H3K9me2 at the Nfat1 promoter. These results suggest that Nfat1 is an essential transcriptional regulator of chondrocyte homeostasis in adult articular cartilage. Age-dependent Nfat1 expression in articular chondrocytes is regulated by dynamic histone methylation, one of the epigenetic mechanisms that regulate gene transcription.

Primary neoplasms of bones in mice: retrospective study and review of literature

To compare and summarize the mechanisms, frequencies of occurrence, and classification schemes of spontaneous, experimental, and genetically engineered mouse skeletal neoplasms, the literature was reviewed, and archived case material at The Jackson Laboratory was examined. The frequency of occurrence of spontaneous bone neoplasms was less than 1% for most strains, with the exceptions of osteomas in CF-1 (5.5% and 10% in two studies) and OF-1 outbred strains (35%), and osteosarcomas in NOD/ShiLtJ (11.5%) and NOD-derived (7.1%) mice. The frequency was 100% for osteochondromas induced by conditional inactivation of exostoses (multiple) 1 (Ext1) in chondrocytes, osteosarcomas induced by tibial intramedullary inoculation of Moloney murine sarcoma virus, and osteosarcomas induced by conditional inactivation of Trp53-with or without inactivation of Rb1-in osteoblast precursors. Spontaneous osteogenic neoplasms were more frequent than spontaneous cartilaginous and vascular types. Malignant neoplasms were more frequent than benign ones. The age of occurrence for spontaneous neoplasms ranged from 37 to 720 days (M = 316.35) for benign neoplasms and 35 to 990 (M = 299.28) days for malignant. In genetically engineered mice, the average age of occurrence ranged from 28 to 70 days for benign and from 35 to 690 days for malignant. Histologically, nonosteogenic neoplasms were similar across strains and mutant stocks; osteogenic neoplasms exhibited greater diversity. This comparison and summarization of mouse bone neoplasms provides valuable information for the selection of strains to create, compare, and validate models of bone neoplasms.

Transcription factor Nfat1 deficiency causes osteoarthritis through dysfunction of adult articular chondrocytes

Osteoarthritis (OA) is the most common form of joint disease in middle-aged and older individuals. Previous studies have shown that over-expression of matrix-degrading proteinases and proinflammatory cytokines is associated with osteoarthritic cartilage degradation. However, it remains unclear which transcription factors regulate the expression of these cartilage-degrading molecules in articular chondrocytes. This study demonstrated that mice lacking Nfat1, a member of the nuclear factor of activated T cells (NFAT) transcription factors, exhibited normal skeletal development but displayed loss of type II collagen (collagen-2) and aggrecan with over-expression of specific matrix-degrading proteinases and proinflammatory cytokines in young adult articular cartilage of load-bearing joints. These initial changes are followed by articular chondrocyte proliferation/clustering, progressive articular surface destruction, periarticular chondro-osteophyte formation and exposure of thickened subchondral bone, all of which resemble human OA. Forced expression of Nfat1 delivered with lentiviral vectors in cultured 3 month-old primary Nfat1 knockout (Nfat1(-/-)) articular chondrocytes partially or completely rescued the abnormal catabolic and anabolic activities of Nfat1(-/-) articular chondrocytes. These new findings revealed a previously unrecognized critical role of Nfat1 in maintaining the physiological function of differentiated adult articular chondrocytes through regulating the expression of specific matrix-degrading proteinases and proinflammatory cytokines. Nfat1 deficiency causes OA due to an imbalance between the catabolic and anabolic activities of adult articular chondrocytes, leading to articular cartilage degradation and failed repair activities in and around articular cartilage. These results may provide new insights into the aetiology, pathogenesis and potential therapeutic strategies for osteoarthritis.

Quantitative trait locus that determines the cross-sectional shape of the femur in SAMP6 and SAMP2 mice

We segregated a QTL on chromosome 11 that affects femoral cross-sectional shape during growth by generating a congenic strain and an additional 16 subcongenic strains of the senescence-accelerated mouse strain, SAMP6. The QTL region was narrowed down to a 10.0-Mbp region.

INTRODUCTION

Genetic background is known to affect bone characteristics. However, little is known about how polymorphic genes modulate bone shape. In a previous study using SAMP2 and SAMP6 mice, we reported a quantitative trait locus (QTL) on chromosome (Chr) 11 that had significant linkage to peak relative bone mass in terms of cortical thickness index (CTI) in male mice. We named it Pbd1. Here we aimed to clarify the effects of Pbd1 on skeletal phenotype in male mice and to narrow down the QTL region.

MATERIALS AND METHODS

We generated a congenic strain named P6.P2-Pbd1(b), carrying a 39-cM SAMP2-derived Chr11 interval on a SAMP6 genetic background. Sixteen subcongenic strains with smaller overlapping intervals on the SAMP6 background were generated from P6.P2-Pbd1(b) to narrow the region of interest. The effects of Pbd1 on bone properties were determined. Gene expression analysis of all candidate genes in Pbd1 was performed using real-time RT-PCR.

RESULTS

The CTI of strain P6.P2-Pbd1(b) at 16 wk was higher than that of SAMP6. This was not caused by differences in cortical thickness but by cross-sectional shape. Morphological analysis by microCT revealed that the femoral cross-sectional shape of P6.P2-Pbd1(b) (and the other subcongenic strains with higher CTI or bone area fraction [BA/TA]) was more compressed anteroposteriorly than that of SAMP6, which was associated with superior mechanical properties. This feature was formed during bone modeling up to 16 wk of age. Subcongenic strains with a higher CTI showed significant increases in endocortical mineral apposition rate and significant reductions in periosteal mineral apposition rate at 8 wk compared with those of the SAMP6. The Pbd1 locus was successfully narrowed down to a 10.0-Mbp region, and the expression analysis suggested a candidate gene, Cacng4.

CONCLUSIONS

The Pbd1 affects femoral cross-sectional shape by regulating the rate of endocortical and periosteal bone formation of the femur during postnatal growth.

Peripheral Nerve Allografts Stored in Green Tea Polyphenol Solution

BACKGROUND

We previously demonstrated the successful 1-month storage of peripheral nerve segments in a green tea polyphenol extract. We investigated whether this method could reduce the donor-host immune reaction associated with peripheral nerve allotransplantation.

METHODS

Sciatic nerve segments (20 mm long) were harvested from Dark Agouti (DA) rats, stored in polyphenol solution (1 mg/mL) for 1 month, and transplanted into recipient major histocompatibility complex-mismatched Lewis rats to bridge 15-mm-long sciatic nerve gaps (polyphenol-treated allograft group). The controls were an isograft group (nerve segments harvested from Lewis rats were immediately transplanted into Lewis rats), a polyphenol-treated isograft group (nerve segments harvested from Lewis rats were treated by polyphenol in the same method and transplanted into Lewis rats), and a fresh allograft group (nerve segments harvested from DA rats were transplanted into Lewis rats without storage). To investigate the origins of the cells in the transplanted nerves, sciatic nerve segments harvested from the male DA rat donors were transplanted into female Lewis rat recipients; genomic DNA was extracted from each nerve segment and amplified by polymerase chain reaction using primers specific for the rat sex-determining region of the Y-chromosome (Sry).

RESULTS

Nerve regeneration in the polyphenol-treated allograft group was similar to that in the isografted group. Sry-specific bands were detected in all samples in the sex-mismatched polyphenol-treated allograft specimens despite their major histocompatibility complex incompatibility.

CONCLUSIONS

Storage in green tea polyphenol solution can reduce both ischemic damage to nerve tissue and donor-host immune reactions after allotransplantation.

Mutation analysis of the RECQL4 gene in sporadic osteosarcomas

Osteosarcoma (OS) is the most prevalent malignant tumor among cases of Rothmund-Thomson syndrome (RTS) with germline mutations of the RECQL4 gene, a member of the RecQ helicase family. We investigated the involvement of the RECQL4 gene in the development of OS unrelated to RTS. RECQL4 mRNA was detected in 9 of 9 OS cell lines by Northern blotting and 26 of 26 OS tumors by RT-PCR. Direct sequencing of the entire coding region along with flanking splice junctions and 13 small (< 100 bp) introns in 71 OS tumors revealed 2 sites with a single-base change causing an amino acid change (G1814A for R355Q and C2474T for P441S) and one site with a 6 bp inframe deletion (4837-42delTGCACC for CT857-8del). Identical genotypes were found in corresponding normal tissues in all cases, and the frequency of each allele was not significantly different between OS and control populations. Our data indicate that the RECQL4 gene is not a frequent target for somatic mutations in sporadic OS unrelated to RTS.

Expression of the chondromodulin-I gene in chondrosarcomas

We investigated the expression of the Chondromodulin-I (ChM-I) gene, a putative tumor suppressor gene in cartilaginous tumors, by quantitative RT-PCR in 15 chondrosarcomas (CSs). Eight CSs expressed the ChM-I gene at the level higher than those in articular cartilage (positive cases), whereas the expression of the ChM-I gene in the remaining seven CSs was lower than those in articular cartilage (negative cases). All of five peripheral CS were positive, and the ChM-I positive tumors shared expression profiles of cartilage-related genes with articular cartilage cells. On the other hand, all of four central CSs without extramedullary lesions were negative, and the ChM-I negative tumors expressed the parathyroid hormone-related peptide gene at the lower level and the COL10A1 genes at the higher level than articular cartilage cells. Neither the histological grade nor the rate of recurrence showed clear association with the level of ChM-I gene expression. These results suggested that the expression of ChM-I gene in CS has no direct role in tumorigenesis but rather reflects the site of tumor development and therefore precursor of tumor cells.