α5β1 integrin induces the expression of noncartilaginous procollagen gene expression in articular chondrocytes cultured in monolayers

Introduction

Articular chondrocytes undergo an obvious phenotypic change when cultured in monolayers. During this change, or dedifferentiation, the expression of type I and type III procollagen is induced where normal chondrocytes express little type I and type III procollagen. In this study, we attempted to determine the mechanism(s) for the induction of such procollagen expression in dedifferentiating chondrocytes.

Methods

All experiments were performed using primary-cultured human articular chondrocytes under approval of institutional review boards. Integrin(s) responsible for the induction of type I and type III procollagen expression were specified by RNAi experiments. The signal pathway(s) involved in the induction were determined by specific inhibitors and RNAi experiments. Adenovirus-mediated experiments were performed to identify a small GTPase regulating the activity of integrins in dedifferentiating chondrocytes. The effect of inhibition of integrins on dedifferentiation was investigated by experiments using echistatin, a potent disintegrin. The effect of echistatin was investigated first with monolayer-cultured chondrocytes, and then with pellet-cultured chondrocytes.

Results

In dedifferentiating chondrocytes, α5β1 integrin was found to be involved in the induction of type I and type III procollagen expression. The induction was known to be mediated by v-akt murine thymoma viral oncogene homolog (AKT) signaling. Among the three AKT isoforms, AKT1 seemed to be most involved in the signaling. Elated RAS viral (r-ras) oncogene homolog (RRAS) was considered to regulate the progression of dedifferentiation by modulating the affinity and avidity of α5β1 integrin to ligands. Echistatin inhibited dedifferentiation of monolayer-cultured chondrocytes. Furthermore, the matrix formed by pellet-cultured chondrocytes more closely resembled that of normal cartilage compared with the controls.

Conclusions

The result of this study has shown, for the first time, that α5β1 integrin may be responsible for the induction of non-cartilaginous collagen expression in chondrocytes undergoing dedifferentiation. Again, this study has shown that the inhibition of ligand ligation to integrins may be an effective strategy to inhibit phenotypic change of cultured chondrocytes, and to improve the quality of matrix synthesized by primary cultured chondrocytes.     

Isolation and Purification of Fucoidin from Brown Seaweed Pelvetia wrightii

A highly purified fucoidin was isolated from Pelvetia wrightii by an improved method, which involves the removal of alginate with calcium chloride solution and purification with cetylpyridinium chloride (CPC).

To this end, the critical salt concentrations of the cetylpyridinium complex of alginic acid and fucoidin in salt solutions (KCl, NaCl, CaCl₂) were determined.

The fucoidin of this alga contained both fucose and galactose as its constituents, in a ratio of approximately 10:1, and it is considered to be a galactofucan sulfate.     

Can Camera Traps Monitor Komodo Dragons a Large Ectothermic Predator?

Camera trapping has greatly enhanced population monitoring of often cryptic and low abundance apex carnivores. Effectiveness of passive infrared camera trapping, and ultimately population monitoring, relies on temperature mediated differences between the animal and its ambient environment to ensure good camera detection. In ectothermic predators such as large varanid lizards, this criterion is presumed less certain. Here we evaluated the effectiveness of camera trapping to potentially monitor the population status of the Komodo dragon (Varanus komodoensis), an apex predator, using site occupancy approaches. We compared site-specific estimates of site occupancy and detection derived using camera traps and cage traps at 181 trapping locations established across six sites on four islands within Komodo National Park, Eastern Indonesia. Detection and site occupancy at each site were estimated using eight competing models that considered site-specific variation in occupancy (ψ)and varied detection probabilities (p) according to detection method, site and survey number using a single season site occupancy modelling approach. The most parsimonious model [ψ (site), p (site*survey); ω = 0.74] suggested that site occupancy estimates differed among sites. Detection probability varied as an interaction between site and survey number. Our results indicate that overall camera traps produced similar estimates of detection and site occupancy to cage traps, irrespective of being paired, or unpaired, with cage traps. Whilst one site showed some evidence detection was affected by trapping method detection was too low to produce an accurate occupancy estimate. Overall, as camera trapping is logistically more feasible it may provide, with further validation, an alternative method for evaluating long-term site occupancy patterns in Komodo dragons, and potentially other large reptiles, aiding conservation of this species.     

Epistatic Interaction between BANK1 and BLK in Rheumatoid Arthritis: Results from a Large Trans-Ethnic Meta-Analysis

Background

BANK1 and BLK belong to the pleiotropic autoimmune genes; recently, epistasis between BANK1 and BLK was detected in systemic lupus erythematosus. Although BLK has been reproducibly identified as a risk factor in rheumatoid arthritis (RA), reports are conflicting about the contribution of BANK1 to RA susceptibility. To ascertain the real impact of BANK1 on RA genetic susceptibility, we performed a large meta-analysis including our original data and tested for an epistatic interaction between BANK1 and BLK in RA susceptibility.

Patients and Methods

We investigated data for 1,915 RA patients and 1,915 ethnically matched healthy controls genotyped for BANK1 rs10516487 and rs3733197 and BLK rs13277113. The association of each SNP and RA was tested by logistic regression. Multivariate analysis was then used with an interaction term to test for an epistatic interaction between the SNPs in the 2 genes.

Results

None of the SNPs tested individually was significantly associated with RA in the genotyped samples. However, we detected an epistatic interaction between BANK1 rs3733197 and BLK rs13277113 (P_interaction = 0.037). In individuals carrying the BLK rs13277113 GG genotype, presence of the BANK1 rs3733197 G allele increased the risk of RA (odds ratio 1.21 [95% confidence interval 1.04–1.41], P = 0.015. Combining our results with those of all other studies in a large trans-ethnic meta-analysis revealed an association of the BANK1 rs3733197 G allele and RA (1.11 [1.02–1.21], P = 0.012).

Conclusion

This study confirms BANK1 as an RA susceptibility gene and for the first time provides evidence for epistasis between BANK1 and BLK in RA. Our results illustrate the concept of pleiotropic epistatic interaction, suggesting that BANK1 and BLK might play a role in RA pathogenesis.     

Human Leukocyte Antigen and Systemic Sclerosis in Japanese: The Sign of the Four Independent Protective Alleles,DRB1*13:02, DRB1*14:06, DQB1*03:01, and DPB1*02:01

ObjectiveSeveral studies on associations between human leukocyte antigen (HLA) allele frequencies and susceptibility to systemic sclerosis (SSc) have been reported. Anti-centromere antibodies (ACA) and anti-topoisomerase I antibodies (ATA) are found in SSc patients. Here, we sought to identify HLA alleles associated with SSc in Japanese, and explored their associations with SSc phenotypes including the presence of autoantibodies.MethodsAssociations of HLA-DRB1, DQB1, and DPB1 were analyzed in 463 Japanese SSc patients and 413 controls.ResultsWe found that DRB1*13:02 (P = 0.0011, Pc = 0.0319, odds ratio [OR] 0.46, 95% confidence interval [CI] 0.29–0.73), DRB1*14:06 (P = 6.60X10^-5, Pc = 0.0020, OR 0.05, 95%CI 0.01–0.41), DQB1*03:01 (P = 0.0009, Pc = 0.0150, OR 0.56, 95%CI 0.40–0.79), and DPB1*02:01 (P = 5.16X10^-6, Pc = 8.77X10^-5, OR 0.52, 95%CI 0.39–0.69) were protectively associated with SSc. In addition, these four alleles seemed to be independently associated with the protection against the susceptibility of SSc. On the other hand, we could not find predisposing alleles for overall SSc. With respect to SSc subsets, a tendency for these four alleles to be protectively associated was observed. However, there was a significant association between DRB1*01:01, DRB1*10:01, DQB1*05:01, and DPB1*04:02 and the susceptibility to SSc with ACA. On the other hand, the presence of DRB1*15:02, DQB1*06:01, DPB1*03:01, and DPB1*09:01 was associated with SSc with ATA.ConclusionThus, the present study has identified protective associations of the four HLA class II alleles with overall Japanese SSc and predisposing associations of HLA class II alleles with Japanese SSc subsets.     

Development of an optimized 5-stage protocol for the in vitro preparation of insulin-secreting cells from mouse ES cells

In order to produce insulin-secreting cells with a high value of glucose-stimulated insulin secretion (GSIS) from mouse embryonic stem cells, we have developed an optimized 5-stage protocol by referring to culture conditions so far reported elsewhere. This protocol is characterized by 4 points: (1) use of an activin-free medium in the first stage, (2) use of gelatin/fibronectin coated culture dishes in 1–4 stages throughout, (3) removal of undifferentiated cells by cell sorter at the end of 4th stage, and (4) sedimental culture in the 5th stage. GSIS value of the produced cells reached 2.4, that was at a higher rank of those so far reported. The produced cells were transplanted in diabetes model mice but no remedy effect was observed. Then transplantation was conducted in pre-diabetes model mice, in which GSIS was impaired without affecting insulin producing function. The transplantation of 5 × 10⁶ cells resulted in a marked improvement of glucose tolerance within 20 days. This effect decreased but was still observed at 120 days post-transplantation. This demonstrates the feasibility of the novel optimized protocol.     

Optimum modification for the highest cytotoxicity of cationized ribonuclease

Cationization of a protein is considered to be a powerful strategy for internalizing a functional protein into cells. Cationized proteins appear to adsorb to the cell surface by electrostatic interactions, then enter the cell in a receptor- and transporter-independent fashion. Thus, in principle, all cell types appear to take up cationized proteins. Since ribonucleases (RNases) have a latent cytotoxic potential, cationized RNases could be useful cancer chemotherapeutics. In this study, we investigated the effect of the degree of cationization on the cytotoxicity of RNase A by modifying carboxyl groups with ethylenediamine. We found that there is an optimum degree of modification for cytotoxicity, in which 5 to 7 out of 11 carboxyl groups in RNase A are modified, toward MCF-7 and 3T3-SV-40 cells. More interestingly, the cytotoxicity of cationized RNase As correlates well with the value of [RNase activity] x [estimated concentration of RNase free from RNase inhibitor], mimicking the practical enzymatic activity of cationized RNase As in cytosol. The results indicate that cationization of a protein to an optimum level is important for maintaining protein function in the cytosol. Sophisticated protein cationization techniques will help to advance protein transduction technology.     

Three-dimensional crystal structure of human eosinophil cationic protein (RNase 3) at 1.75 A resolution

Eosinophil cationic protein (ECP; RNase 3) is a human ribonuclease found only in eosinophil leukocytes that belongs to the RNase A superfamily. This enzyme is bactericidal, helminthotoxic and cytotoxic to mammalian cells and tissues. The protein has been cloned, heterologously overexpressed, purified and crystallized. Its crystal structure has been determined and refined using data up to 1. 75 A resolution. The molecule displays the alpha+beta folding topology typical for members of the ribonuclease A superfamily. The catalytic active site residues are conserved with respect to other ribonucleases of the superfamily but some differences appear at substrate recognition subsites, which may account, in part, for the low catalytic activity. Most strikingly, 19 surface-located arginine residues confer a strong basic character to the protein. The high concentration of positive charges and the particular orientation of the side-chains of these residues may also be related to the low activity of ECP as a ribonuclease and provides an explanation for its unique cytotoxic role through cell membrane disruption.     

Differential Regulation of Intracellular Signaling Systems by Sodium Fluoride in Rat Glioma Cells

Abstract: We investigated the rapid and slow effects of NaF on intracellular signaling systems such as Ca²⁺ homeostasis and cyclic GMP (cGMP) generation in rat glioma C6 cells, using the Ca²⁺-sensitive dye fura-2 and cGMP enzyme immunoassay. We found that the following: (a) NaF enhanced cGMP generation in a concentration-dependent manner. This enhancement was abolished by pretreatment with 100 µ M BAPTA tetraacetoxymethyl ester or in the presence of W-7 in a concentration-dependent manner. N ^G-Monomethyl- l -arginine (NMMA), a competitive inhibitor of nitric oxide synthase (NOS), also inhibited the NaF-induced generation of cGMP. These results suggest that NaF-induced cGMP generation occurs via a calcium/calmodulin- and NOS-dependent pathway. (b) The basal intracellular Ca²⁺ concentration ([Ca²⁺]_i) was transiently greater at 1 and 3 h after pretreatment with NaF. W-7 and W-13 antagonized the increase in [Ca²⁺]_i, whereas NMMA had little effect. This suggests that the NaF-induced change in basal [Ca²⁺]_i was mediated by a calmodulin-dependent pathway but was independent of a NOS-sensitive pathway. (c) The serotonin (5-HT)-induced intracellular mobilization of Ca²⁺ was reduced by pretreating the cells with NaF. The reduction in Ca²⁺ mobilization was antagonized by genistein, a tyrosine kinase inhibitor. W-7, W-5, and H-8 had no effect. Results suggest that NaF differentially regulates the cGMP generation, basal [Ca²⁺]_i, and 5-HT_2A receptor function in C6 glioma cells.     

Serotonin differentially regulates short- and long-term prediction of rewards in the ventral and dorsal striatum

Background

The ability to select an action by considering both delays and amount of reward outcome is critical for maximizing long-term benefits. Although previous animal experiments on impulsivity have suggested a role of serotonin in behaviors requiring prediction of delayed rewards, the underlying neural mechanism is unclear.

Methodology/Principal Findings

To elucidate the role of serotonin in the evaluation of delayed rewards, we performed a functional brain imaging experiment in which subjects chose small-immediate or large-delayed liquid rewards under dietary regulation of tryptophan, a precursor of serotonin. A model-based analysis revealed that the activity of the ventral part of the striatum was correlated with reward prediction at shorter time scales, and this correlated activity was stronger at low serotonin levels. By contrast, the activity of the dorsal part of the striatum was correlated with reward prediction at longer time scales, and this correlated activity was stronger at high serotonin levels.

Conclusions/Significance

Our results suggest that serotonin controls the time scale of reward prediction by differentially regulating activities within the striatum.