👤 Laurence Gall

Axin1 is a negative regulator of wingless-type MMTV integration site family, member 1 (Wnt)/β-catenin signaling with tumor-suppressor function. The Wnt pathway has a critical role in the intestine, both during homeostasis and cancer, but the role of Axin1 remains elusive. We assessed the role of Axin1 in normal intestinal homeostasis, with control, epithelial-specific, Axin1-knockout mice (Axin1 We found that Axin1 was dispensable for normal intestinal homeostasis and redundant with Axin2 for Wnt pathway down-regulation. Axin1 deficiency in intestinal epithelial cells rendered mice more susceptible to chemically induced colon carcinogenesis, but reduced dextran sulfate sodium-induced colitis by attenuating the induction of a proinflammatory program. RNA-seq analyses identified an interferon γ/T-helper1 immune program controlled by Axin1 that enhances the inflammatory response and protects against CRC. The Axin1-dependent gene expression signature was applied to human CRC samples and identified a group of patients with potential vulnerability to immune checkpoint blockade therapies. Our study establishes, in vivo, that Axin1 has redundant function with Axin2 for Wnt down-regulation and infers a new role for Axin1. Physiologically, Axin1 stimulates gut inflammation via an interferon γ/Th1 program that prevents tumor growth. Linked to its T-cell-mediated effect, the colonic Axin1 signature offers therapeutic perspectives for CRC. Show less

Elevation of nonfasting triglyceride (TG) levels above 1.8 g/L (2 mmol/L) is associated with increased risk of cardiovascular diseases. Exacerbated postprandial hypertriglyceridemia (PP-HTG) and metabolic context both modulate the overall efficacy of the reverse cholesterol transport (RCT) pathway, but the specific contribution of exaggerated PP-HTG on RCT efficacy remains indeterminate. Healthy male volunteers ( Show less

Serum cholesterol efflux capacity, a biomarker that integrates contributors and modulators of the initial step of the reverse cholesterol transport, has been associated with atherosclerosis independently of high-density lipoprotein (HDL) cholesterol level. The authors evaluated the prognostic impact of serum cholesterol efflux capacity on mortality in a large cohort of patients hospitalized for an acute myocardial infarction (MI). Serum cholesterol efflux capacity, cholesteryl ester transfer protein (CETP) activity, total cholesterol, low-density lipoprotein cholesterol, HDL cholesterol, and triglyceride levels were measured in 1,609 consecutive patients admitted with an acute MI. The primary endpoint was all-cause mortality evaluated at 6 years with a median follow-up of 1.9 years (interquartile range: 1.5 to 4.2 years). An analysis by quartile of serum cholesterol efflux capacity was also performed. In a fully adjusted model that included age, sex, traditional cardiovascular risk factors including lipid levels, and prognostic factors of MI, serum cholesterol efflux capacity was a strong predictor of survival (adjusted hazard ratio for mortality per 1-SD increase in serum cholesterol efflux capacity, 0.79; 95% confidence interval: 0.66 to 0.95; p = 0.0132). Patients displaying an elevated serum cholesterol efflux capacity had a marked lower rate of mortality at 6 years (adjusted hazard ratio: 0.54 [0.32 to 0.89]; p = 0.0165) as compared with patients with reduced serum cholesterol efflux capacity. Serum cholesterol efflux capacity, an integrative marker of reverse cholesterol transport pathway and efficacy, was inversely associated with all-cause mortality in MI patients independently of HDL cholesterol level and other risk factors. Show less

Circulating metabolites associated with insulin sensitivity may represent useful biomarkers, but their causal role in insulin sensitivity and diabetes is less certain. We previously identified novel metabolites correlated with insulin sensitivity measured by the hyperinsulinemic-euglycemic clamp. The top-ranking metabolites were in the glutathione and glycine biosynthesis pathways. We aimed to identify common genetic variants associated with metabolites in these pathways and test their role in insulin sensitivity and type 2 diabetes. With 1,004 nondiabetic individuals from the RISC study, we performed a genome-wide association study (GWAS) of 14 insulin sensitivity-related metabolites and one metabolite ratio. We replicated our results in the Botnia study (n = 342). We assessed the association of these variants with diabetes-related traits in GWAS meta-analyses (GENESIS [including RISC, EUGENE2, and Stanford], MAGIC, and DIAGRAM). We identified four associations with three metabolites-glycine (rs715 at CPS1), serine (rs478093 at PHGDH), and betaine (rs499368 at SLC6A12; rs17823642 at BHMT)-and one association signal with glycine-to-serine ratio (rs1107366 at ALDH1L1). There was no robust evidence for association between these variants and insulin resistance or diabetes. Genetic variants associated with genes in the glycine biosynthesis pathways do not provide consistent evidence for a role of glycine in diabetes-related traits. Show less

The early events in the nuclear reprogramming process during somatic cell nuclear transfer (SCNT) consist of morphological remodeling of the donor nucleus including premature chromosome condensation (PCC). In the present study, the objective was to increase oocyte M-Phase Promoting Factor (MPF) kinase activity and to examine the fate of the donor nucleus and the development of SCNT embryos thereafter. Indeed, in controls, recipient oocytes activated upon nuclear transfer, undergo a decrease in MPF activity, responsible for the inability to promote PCC in 77.8% of reconstituted embryos. Here we showed that exposure of the recipient oocyte to the proteasome inhibitor MG132 prior to fusion inhibited the degradation of cyclin B, which normally occurred immediately after activation by electro stimulation, and therefore sustained a high level of MPF. Treatment with MG132 also significantly increased the percentage of SCNT embryos with PCC when compared to the nontreated SCNT control embryos (94.1 vs. 22.2%, respectively, p < 0.01). The frequency of development to the blastocyst stage did not differ between MG132-treated or untreated recipient oocytes. However, we observed a significant increase of the total cells number in embryos produced after MG132 treatment. Investigation of the global nuclear organization by immunodetection of heterochromatin protein 1 (CBX1) showed that SCNT embryos derived from MG132-treated recipient oocytes displayed organization patterns similar to the ones observed in IVF embryos in contrast to the nontreated SCNT controls. Taken together, these results suggest that the PCC induced by MG132 treatment allows reorganization of the chromatin at an appropriate time potentially, leading to better reprogramming. Show less

The t(12;21)(p13;q22) translocation is found in 20 to 25% of cases of childhood B-lineage acute lymphoblastic leukemia (B-ALL). This rearrangement results in the fusion of ETV6 (TEL) and RUNX1 (AML1) genes and defines a relatively uniform category, although only some patients suffer very late relapse. TEL/AML1-positive patients are thus an interesting subgroup to study, and such studies should elucidate the biological processes underlying TEL/AML1 pathogenesis. We report an analysis of gene expression in 60 children with B-lineage ALL using Agilent whole genome oligo-chips (44K-G4112A) and/or real time RT-PCR. We compared the leukemia cell gene expression profiles of 16 TEL/AML1-positive ALL patients to those of 44 TEL/AML1-negative patients, whose blast cells did not contain any additional recurrent translocation. Microarray analyses of 26 samples allowed the identification of genes differentially expressed between the TEL/AML1-positive and negative ALL groups. Gene enrichment analysis defined five enriched GO categories: cell differentiation, cell proliferation, apoptosis, cell motility and response to wounding, associated with 14 genes -RUNX1, TCFL5, TNFRSF7, CBFA2T3, CD9, SCARB1, TP53INP1, ACVR1C, PIK3C3, EGFL7, SEMA6A, CTGF, LSP1, TFPI - highlighting the biology of the TEL/AML1 sub-group. These results were first confirmed by the analysis of an additional microarray data-set (7 patient samples) and second by real-time RT-PCR quantification and clustering using an independent set (27 patient samples). Over-expression of RUNX1 (AML1) was further investigated and in one third of the patients correlated with cytogenetic findings. Gene expression analyses of leukemia cells from 60 children with TEL/AML1-positive and -negative B-lineage ALL led to the identification of five biological processes, associated with 14 validated genes characterizing and highlighting the biology of the TEL/AML1-positive ALL sub-group. Show less