Effects of an environmentally relevant concentration of diuron on oyster genitors during gametogenesis: responses of early molecular and cellular markers and physiological impacts

Genitors of the Pacific oyster Crassostrea gigas were submitted during gametogenesis to a short pulse exposure to the herbicide diuron at a realistic environmental concentration. Histological analysis showed no effect of diuron on gametogenesis course, sex ratio and reproductive effort. A non-significant increase in testosterone and progesterone levels was observed in genitors exposed to the herbicide. At cell level, diuron exposure was shown to modulate the phagocytic activity of circulating hemocytes. The results of a transcriptional analysis showed that diuron affected the expression of genes belonging to functions known to play a major role during oyster gametogenesis such as gene transcription regulation, DNA replication and repair, DNA methylation and cytokinesis. Taking into account the results we previously obtained on the same genitors, this study showed a negative effect of diuron on oyster reproduction by inducing both structural and functional modifications of the DNA.

Age-dependent expression of osteochondrosis-related genes in equine leukocytes

INTRODUCTION

Osteochondrosis (OC) is a developmental disease in horses which has a significant impact on the horse's welfare and performance. The early disturbance in the process of endochondral ossification progresses to inflammatory and repair processes in older horses. Previously, differentially expressed genes in leukocytes of OC-affected horses have been identified. The aim of the present study is to detect age-related changes in these differentially expressed genes.

MATERIALS AND METHODS

The expression of OC-related genes was analysed by real-time PCR and subsequent statistical analysis (ΔΔCT) in the leukocytes of 135 Belgian Warmblood horses divided into three different age groups: <12 months (n=47), 18-24 months (n=50) >30 months (n=38).

RESULTS

Relative expression of genes of horses less than 12 months of age showed significant induction of the genes MGAT4A, PRKCG, MHCI, ApoB, ApoB3G, B4GALT6 and a significantly lower expression of the genes OAS3. Horses of 18-24 months of age, showed a significantly higher expression of the genes TBC1D9, MGAT4A, IFIH1, MHCIIa and MMP1. Horses of more than 30 months of age showed a significantly higher expression of the genes MGAT4A, HP, SECTM1 compared with their age-matched control groups.

CONCLUSIONS

The study demonstrates that OC-related genes are differentially expressed in horses of different ages compared with their age-matched controls. Some of the genes may be implicated in cell signalling and differentiation as well as carbohydrate and lipid metabolism and inflammation. However, the causal relationship between the differentially expressed genes and the development and progression of the OC lesions needs to be determined.

A randomized, placebo-controlled phase III trial of masitinib plus gemcitabine in the treatment of advanced pancreatic cancer

BACKGROUND

Masitinib is a selective oral tyrosine-kinase inhibitor. The efficacy and safety of masitinib combined with gemcitabine was compared against single-agent gemcitabine in patients with advanced pancreatic ductal adenocarcinoma (PDAC).

PATIENTS AND METHODS

Patients with inoperable, chemotherapy-naïve, PDAC were randomized (1 : 1) to receive gemcitabine (1000 mg/m(2)) in combination with either masitinib (9 mg/kg/day) or a placebo. The primary endpoint was overall survival (OS) in the modified intent-to-treat population. Secondary OS analyses aimed to characterize subgroups with poor survival while receiving single-agent gemcitabine with subsequent evaluation of masitinib therapeutic benefit. These prospectively declared subgroups were based on pharmacogenomic data or a baseline characteristic.

RESULTS

Three hundred and fifty-three patients were randomly assigned to receive either masitinib plus gemcitabine (N = 175) or placebo plus gemcitabine (N = 178). Median OS was similar between treatment-arms for the overall population, at respectively, 7.7 and 7.1 months, with a hazard ratio (HR) of 0.89 (95% CI [0.70; 1.13]. Secondary analyses identified two subgroups having a significantly poor survival rate when receiving single-agent gemcitabine; one defined by an overexpression of acyl-CoA oxidase-1 (ACOX1) in blood, and another via a baseline pain intensity threshold (VAS > 20 mm). These subgroups represent a critical unmet medical need as evidenced from median OS of 5.5 months in patients receiving single-agent gemcitabine, and comprise an estimated 63% of patients. A significant treatment effect was observed in these subgroups for masitinib with median OS of 11.7 months in the 'ACOX1' subgroup [HR = 0.23 (0.10; 0.51), P = 0.001], and 8.0 months in the 'pain' subgroup [HR = 0.62 (0.43; 0.89), P = 0.012]. Despite an increased toxicity of the combination as compared with single-agent gemcitabine, side-effects remained manageable.

CONCLUSIONS

The present data warrant initiation of a confirmatory study that may support the use of masitinib plus gemcitabine for treatment of PDAC patients with overexpression of ACOX1 or baseline pain (VAS > 20mm). Masitinib's effect in these subgroups is also supported by biological plausibility and evidence of internal clinical validation.

TRIAL REGISTRATION

ClinicalTrials.gov:NCT00789633.

MicroRNAs: new candidates for the regulation of the human cumulus-oocyte complex

STUDY QUESTION

What is the expression pattern of microRNAs (miRNAs) in human cumulus-oocyte complexes (COCs)?

SUMMARY ANSWER

Several miRNAs are enriched in cumulus cells (CCs) or oocytes, and are predicted to target genes involved in biological functions of the COC.

WHAT IS KNOWN ALREADY

The transcriptional profiles of human MII oocytes and the surrounding CCs are known. However, very limited data are available about post-transcriptional regulators, such as miRNAs. This is the first study focussing on the identification and quantification of small RNAs, including miRNAs, in human oocytes and CCs using a deep-sequencing approach.

STUDY DESIGN, SIZE, DURATION

MII oocytes and CCs were collected from women who underwent IVF.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Using the Illumina/deep-sequencing technology, we analyzed the small RNAome of pooled MII oocytes (n = 24) and CC samples (n = 20). The mRNA targets of CC and MII oocyte miRNAs were identified using in silico prediction algorithms. Using oligonucleotide microarrays, genome-wide gene expression was studied in oocytes (10 pools of 19 ± 3 oocytes/each) and 10 individual CC samples. TaqMan miRNA assays were used to confirm the sequencing results in independent pools of MII oocytes (3 pools of 8 ± 3 oocytes/each) and CC samples (3 pools of 7 ± 3 CCs/each). The functional role of one miRNA, MIR23a, was assessed in primary cultures of human CCs.

MAIN RESULTS AND THE ROLE OF CHANCE

Deep sequencing of small RNAs yielded more than 1 million raw reads. By mapping reads with a single location to the human genome, known miRNAs that were abundant in MII oocytes (MIR184, MIR100 and MIR10A) or CCs (MIR29a, MIR30d, MIR21, MIR93, MIR320a, MIR125a and the LET7 family) were identified. Predicted target genes of the oocyte miRNAs were associated with the regulation of transcription and cell cycle, whereas genes targeted by CC miRNAs were involved in extracellular matrix and apoptosis. Comparison of the predicted miRNA target genes and mRNA microarray data resulted in a list of 224 target genes that were differentially expressed in MII oocytes and CCs, including PTGS2, CTGF and BMPR1B that are important for cumulus-oocyte communication. Functional analysis using primary CC cultures revealed that BCL2 and CYP19A1 mRNA levels were decreased upon MIR23a overexpression.

LIMITATIONS, REASONS FOR CAUTION

Only known miRNAs were investigated in the present study on COCs. Moreover, the source of the material is MII oocytes that failed to fertilize.

WIDER IMPLICATIONS OF THE FINDINGS

The present findings suggest that miRNA could play a role in the regulation of the oocyte and CC crosstalk.

STUDY FUNDING/COMPETING INTEREST(S)

This work was partially supported by a grant from Ferring Pharmaceuticals. The authors of the study have no conflict of interest to report.

TRIAL REGISTRATION NUMBER

Not applicable.

Pmarg-pearlin is a matrix protein involved in nacre framework formation in the pearl oyster Pinctada margaritifera

The shell of pearl oysters is organized in multiple layers of CaCO(3) crystallites packed together in an organic matrix. Relationships between the components of the organic matrix and mechanisms of nacre formation currently constitute the main focus of research into biomineralization. In this study, we characterized the pearlin protein from the oyster Pinctada margaritifera (Pmarg); this shares structural features with other members of a matrix protein family, N14/N16/pearlin. Pmarg pearlin exhibits calcium- and chitin-binding properties. Pmarg pearlin transcripts are distinctively localized in the mineralizing tissue responsible for nacre formation. More specifically, we demonstrate that Pmarg pearlin is localized within the interlamellar matrix of nacre aragonite tablets. Our results support recent models for multidomain matrix protein involvement in nacreous layer formation. We provide evidence here for the existence of a conserved family of nacre-associated proteins in Pteriidae, and reassess the evolutionarily conserved set of biomineralization genes related to nacre formation in this taxa.

Differential expression of the RTP/Drg1/Ndr1 gene product in proliferating and growth arrested cells

Using a differential display method to identify differentiation-related genes in human myelomonocytic U937 cells, we cloned the cDNA of a gene identical to Drg1 and homologous to other recently discovered genes, respectively human RTP and Cap43 and mouse Ndr1 and TDD5 genes. Their open reading frames encode proteins highly conserved between mouse and man but which do not share homology with other know proteins. Conditions in which mRNAs are up-regulated suggest a role for the protein in cell growth arrest and terminal differentiation. We raised antibodies against a synthetic peptide reproducing a characteristic sequence of the putative polypeptide chain. These antibodies revealed a protein with the expected 43 kDa molecular mass, up-regulated by phorbol ester, retinoids and 1,25-(OH)2 vitamin D3 in U937 cells. It was increased in mammary carcinoma MCF-7 cells treated by retinoids and by the anti-estrogen ICI 182,780 but not by 4-hydroxytamoxifen. The mouse Drg1 homologous protein was up-regulated by retinoic acid in C2 myogenic cells. The diversity of situations in which expression of RTP/Drg1/Ndr1 has now been observed shows that it is widely distributed and up-regulated by various agents. Here we show that ligands of nuclear transcription factors involved in cell differentiation are among the inducers of this novel protein.

Transforming growth factor-beta1 is an autocrine mediator of U937 cell growth arrest and differentiation induced by vitamin D3 and retinoids

Vitamin D and retinoids cooperate to inhibit the proliferation and induce the differentiation of human myelomonocytic U937 leukemia cells. In the present work, we investigated the role of TGF-beta as an endogenous mediator of this process. We found that the TGF-beta1 precursor began to accumulate in cell culture supernatants soon after the addition of 1alpha,25 dihydroxyvitamin D3 (VD) and retinoids. We used neutralizing antibodies (AbTGF-beta) and antisense oligonucleotide (AS Oligo) to inhibit its possible effects. Our data demonstrated that AbTGF-beta partially inhibit the expression of the differentiated phenotype, as assessed by measurement of phagocytic activity, response to the chemotactic peptide fMLP, and lysozyme secretion. AS Oligo was also inhibitory, and the effects of AS Oligo and AbTGF-beta were cumulative. Cell growth inhibition induced by VD and retinoids was completely reversed, and differentiation was reduced by about 75% when both inhibitors were associated. Time course experiments based on the delayed addition of AbTGF-beta and AS Oligo showed that TGF-beta1 was required for cell differentiation 24 h after the addition of inducers. Studies on TGF-beta receptors revealed that, while the expression of type II receptor was stable, the level of type I TGF-beta receptor mRNA and the expression of the protein began to decline early during the differentiation process. As a whole, these results support the notion that an autocrine TGF-beta pathway, activated by VD and retinoids in U937 cells, is involved in the early steps of the process leading to cell growth arrest and differentiation.

Functional specificity of the two retinoic acid receptor RAR and RXR families in myogenesis

In C2 myoblasts, retinoic acid (RA) is an efficient inducer of both growth arrest and differentiation. These RA effects are mediated through at least two classes of retinoic acid receptors (RARs and RXRs), which belong to the nuclear receptor superfamily. To determine the role played by each RAR or RXR family in this model system, we have analysed the effects of RA in C2 myoblasts expressing a dominant negative RAR (dnRAR) or a dominant negative RXR (dnRXR). The stable expression of dnRAR or dnRXR in C2 cells delays the RA-induced growth arrest and differentiation, an effect which is more pronounced in C2-dnRXR myoblasts. Furthermore, the RA-inducible expression of MyoD gene is lost in C2-dnRXR but not in C2-dnRAR cells, indicating that each family of retinoid receptors RAR and RXR may regulate distinct subsets of RA-responsive genes. Finally, using C2 cell lines with different retinoid responsiveness, we provided evidence for a link between the RXR and MyoD families in the process of myogenic differentiation. These results illustrate a critical role for RA-receptors in RA-control of C2 myogenesis and provide tools for studying the function of RA and its receptors during vertebrate development.

Potentiation of VD-induced monocytic leukemia cell differentiation by retinoids involves both RAR and RXR signaling pathways

Retinoids and vitamin D (VD) cooperate to induce the differentiation and inhibit the proliferation of human myelomonocytic leukemia cells. Two classes of retinoids receptors, the RARs and RXRs, respectively, can mediate these effects. RXR forms heterodimers with a variety of nuclear receptors, including RAR and the VD receptor. We have previously found that VD treatment increases RXR alpha levels in myelomonocytic leukemia cells. By immunoanalysis, we observed in the present work that the RAR alpha protein is expressed in proliferating U937, HL-60 and THP-1 human leukemia cells and that VD treatment induces alterations of its electrophoretic pattern, although with large differences between cell lines. In the three cell lines, 9-cis RA, an agonist of both RARs and RXRs, cooperated with VD more efficiently than all-trans RA and RAR-specific synthetic ligands, thus suggesting an involvement of both RAR and RXR pathways in cell differentiation. Using U937 cells as a model, we delineated the relative contributions of RAR and RXR by assessing the effects of receptor-selective synthetic retinoids. The synergy between VD and all-trans RA or RAR-specific agonists (TTNPB and Ro 40-6055) was abrogated by a RAR alpha-specific antagonist (Ro 41-5253), confirming an involvement of RAR alpha. However, the cooperation between VD and 9-cis RA, although reduced, was not suppressed by the antagonist, suggesting also an involvement of the RXR pathway. The role of RXR as a ligand-activated receptor was confirmed using RXR-specific agonists (CD2608 and LGD1069), which also proved able to cooperate with VD. Finally, while each synthetic agonist alone was significantly less potent than 9-cis RA, combinations of the RAR and RXR selective agonists TTNPB and LGD1069 appeared to be as effective as the pan agonist 9-cis-RA. These results confirm that various retinoids can cooperate with VD and demonstrate that, at a whole cell level, optimal effects require the activation of both RAR and RXR receptors.