The Phosphate Transporter PiT1 (Slc20a1) Revealed As a New Essential Gene for Mouse Liver Development

BACKGROUND: PiT1 (or SLC20a1) encodes a widely expressed plasma membrane protein functioning as a high-affinity Na(+)-phosphate (Pi) cotransporter. As such, PiT1 is often considered as a ubiquitous supplier of Pi for cellular needs regardless of the lack of experimental data. Although the importance of PiT1 in mineralizing processes have been demonstrated in vitro in osteoblasts, chondrocytes and vascular smooth muscle cells, in vivo evidence is missing. METHODOLOGY/PRINCIPAL FINDINGS: To determine the in vivo function of PiT1, we generated an allelic series of PiT1 mutations in mice by combination of wild-type, hypomorphic and null PiT1 alleles expressing from 100% to 0% of PiT1. In this report we show that complete deletion of PiT1 results in embryonic lethality at E12.5. PiT1-deficient embryos display severely hypoplastic fetal livers and subsequent reduced hematopoiesis resulting in embryonic death from anemia. We show that the anemia is not due to placental, yolk sac or vascular defects and that hematopoietic progenitors have no cell-autonomous defects in proliferation and differentiation. In contrast, mutant fetal livers display decreased proliferation and massive apoptosis. Animals carrying two copies of hypomorphic PiT1 alleles (resulting in 15% PiT1 expression comparing to wild-type animals) survive at birth but are growth-retarded and anemic. The combination of both hypomorphic and null alleles in heterozygous compounds results in late embryonic lethality (E14.5-E16.5) with phenotypic features intermediate between null and hypomorphic mice. In the three mouse lines generated we could not evidence defects in early skeleton formation. CONCLUSION/SIGNIFICANCE: This work is the first to illustrate a specific in vivo role for PiT1 by uncovering it as being a critical gene for normal developmental liver growth

Peroxiredoxin 6 Fails to Limit Phospholipid Peroxidation in Lung from Cftr-Knockout Mice Subjected to Oxidative Challenge

Oxidative stress plays a prominent role in the pathophysiology of cystic fibrosis (CF). Despite the presence of oxidative stress markers and a decreased antioxidant capacity in CF airway lining fluid, few studies have focused on the oxidant/antioxidant balance in CF cells. The aim of the current study was to investigate the cellular levels of reactive oxygen species (ROS), oxidative damage and enzymatic antioxidant defenses in the lung of Cftr-knockout mice in basal conditions and as a response to oxidative insult

Eicosanoid Release Is Increased by Membrane Destabilization and CFTR Inhibition in Calu-3 Cells

The antiinflammatory protein annexin-1 (ANXA1) and the adaptor S100A10 (p11), inhibit cytosolic phospholipase A2 (cPLA2α) by direct interaction. Since the latter is responsible for the cleavage of arachidonic acid at membrane phospholipids, all three proteins modulate eicosanoid production. We have previously shown the association of ANXA1 expression with that of CFTR, the multifactorial protein mutated in cystic fibrosis. This could in part account for the abnormal inflammatory status characteristic of this disease. We postulated that CFTR participates in the regulation of eicosanoid release by direct interaction with a complex containing ANXA1, p11 and cPLA2α. We first analyzed by plasmon surface resonance the in vitro binding of CFTR to the three proteins. A significant interaction between p11 and the NBD1 domain of CFTR was found. We observed in Calu-3 cells a rapid and partial redistribution of all four proteins in detergent resistant membranes (DRM) induced by TNF-α. This was concomitant with increased IL-8 synthesis and cPLA2α activation, ultimately resulting in eicosanoid (PGE2 and LTB4) overproduction. DRM destabilizing agent methyl-β-cyclodextrin induced further cPLA2α activation and eicosanoid release, but inhibited IL-8 synthesis. We tested in parallel the effect of short exposure of cells to CFTR inhibitors Inh172 and Gly-101. Both inhibitors induced a rapid increase in eicosanoid production. Longer exposure to Inh172 did not increase further eicosanoid release, but inhibited TNF-α-induced relocalization to DRM. These results show that (i) CFTR may form a complex with cPLA2α and ANXA1 via interaction with p11, (ii) CFTR inhibition and DRM disruption induce eicosanoid synthesis, and (iii) suggest that the putative cPLA2/ANXA1/p11/CFTR complex may participate in the modulation of the TNF-α-induced production of eicosanoids, pointing to the importance of membrane composition and CFTR function in the regulation of inflammation mediator synthesis

Etude de l'interaction de la cytokératine 8 et de la protéine CFTR (nouvelle cible thérapeutique pour la mucoviscidose)

La mucoviscidose est une maladie génétique létale causée par des mutations du gène cftr CFTR , la plus fréquente est la délétion d une Phénylalanine en position 508 (F508del) au sein du domaine de liaison aux nucléotides 1 (NBD1). Cette mutation est responsable d un transport intracellulaire défectueux de la protéine CFTR, qui est dégradée avant d atteindre la membrane plasmique. Le défaut d adressage est à l origine de l absence de sécrétion des ions chlorure corrélée à l absorption accrue d ions sodium, entrainant la présence d un mucus épais et visqueux à la surface des cellulesde l épithélialesum pulmonaires. Ce projet de thèse s est focalisé sur l étude deous nous sommes intéressés à l interaction entre la protéine CFTR et le réseau de cytokératines. Les résultats de nos travaux, nous ont conduit à explorer L explorer d une nouvelle piste potentiellement thérapeutiques basée sur l inhibition de l interaction entre la cytokératine 8 (K8) et la forme mutée F508del-CFTR dans la mucoviscidose, en utilisant pendant 72h desune approche siRNA). Cette approche a été testée dans un modèle cellulaire HeLa et dans un modèle murin F508del/F508del. Dans les deux cas Cce traitement a permis d adresser la protéine mutée à la membrane plasmique. La de restaureration de la fonction CFTR. L ensemble de ces résultats suggère que l augmentation d expression l activation de F508del-CFTR induite par une diminution de l expression dea K8 et de l interaction entre ces deux protéines, pourrait être représenter une piste thérapeutique dans la mucoviscidose chez des patients porteurs de la mutation F508delPARIS-BIUSJ-Biologie recherche (751052107) / SudocSudocFranceF

Lipidomics Conquers a Niche, Consolidates Growth

International audienc

The Enigmatic Emerging Role of the C-Maf Inducing Protein in Cancer

International audienceThe C-Maf-Inducing protein (CMIP) was first described as overexpressed in T cell subpopulations of idiopathic nephrotic syndrome (INS) patients. Later, it was found concomitantly upregulated in podocytes. CMIP expression has also been reported in several types of cancer, including blood malignancies and solid tumors, in many cases accompanied by nephrotic syndrome. In addition to these observations, the duality of CMIP overexpression in the kidney and INS lesions, has been extensively reported as one of the adverse effects of anticancer therapy based on anti-receptor tyrosine kinase drugs. As a consequence, a growing body of evidence points at CMIP as playing a role in cancer. This includes its reciprocal regulatory ties with NF-κB and WT1, and the more recent reports showing an involvement in regulatory circuits in cancer cells. The ensemble of the current information justifies to propose CMIP as an important piece of the puzzle of biological systems involved in cancer and other diseases and its potential as a target

Lipidomics: An Evolving Discipline in Molecular Sciences

Recent advances in technologies for lipid analysis have contributed to the consolidation of lipidomics as a distinct discipline in molecular sciences [1–6]. [...