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Renal fibrosis represents the final stage of most chronic kidney diseases and contributes to the progressive and irreversible decline in kidney function with accumulation of extracellular matrix components in the renal parenchyma. The molecular mechanisms governing the renal fibrosis process are complex and remain poorly understood. Recently, the profibrotic role of several microRNAs (miRNAs) has been described in kidney fibrosis. MiRNAs are a new class of, small non-coding RNAs of about 20 nucleotides that act as gene expression negative regulators at the post-transcriptional level. Seminal studies have highlighted the potential importance of miRNA as new therapeutic targets and innovative diagnostic and/or prognostic biomarkers. This review summarizes recent scientific advances on the role played by miRNAs in kidney fibrogenesis and discusses potential clinical applications as well as future research directions., (Copyright © 2015 Association Société de néphrologie. Published by Elsevier SAS. All rights reserved.)

Aging is a complex process that is accompanied by the onset of a series of age-related diseases, including Alzheimer's disease. Aging is controlled by a combination of genetic and environmental factors. Among the genes that regulate aging, the insulin-FOXO signaling pathway plays a central role, as this pathway regulates lifespan in multiple species, such as worms, flies, and mice. In humans, exceptional longevity - being a centenarian - is also associated with genetic variation in this insulin-FOXO pathway. Recent evidence indicates that the FOXO family of transcription factors plays a key role in the self-renewal of adult and embryonic stem cells, which could contribute to tissue regeneration. Understanding the mechanisms underlying aging should help better prevent and treat age-dependent diseases., (© 2012 médecine/sciences – Inserm / SRMS.)

CYLD deubiquitinase has been originally defined as a tumor suppressor based exclusively on genetic findings. Indeed, inactivation of CYLD in humans results in familial cylindromatosis and multiple trichoepithelioma, two pathologies characterized by the development of tumors originating specifically from the skin appendages. A set of recent publications has revealed that recurrent inactivation of CYLD occurs through diverse mechanisms in several forms of cancer, unequivocally confirming its tumor suppressor function. This property is associated with the critical role played by CYLD in negatively regulating several signaling pathway, among them the NF-κB signaling pathway., (© 2011 médecine/sciences - Inserm / SRMS.)

Deimination or citrullination, is a post-translational modification with many facets. It is involved in several basic cellular processes, including gene regulation, embryonic development and terminal differentiation, and also in various pathophysiological mechanisms linked to severe human diseases such as multiple sclerosis and rheumatoid arthritis. Deimination, the calcium-dependent enzymatic conversion of peptidyl-arginine to peptidyl-citrulline, induces a decrease in the charge of the modified proteins with major consequences on their conformation, stability and/or interactions, and therefore on their functions. Five isotypes of peptidylarginine deiminases (1-4 and 6), exist in humans with a variable tissue expression. These highly conserved enzymes are closely regulated at transcriptional and post-transcriptional levels, probably including auto-deimination.

Macrophages are involved in the immune and the inflammatory response. The deregulation of their physiological properties is associated with several pathologies such as atherosclerosis and some cancers. Cytokines action on this blood lineage modulates p21WAF1/CIP1 expression. It appears that this protein may play a role in the inflammation regulation through PPAR (peroxysome proliferator-activated receptors) transcription factors, strongly linked to lipid metabolism. It could also be involved in the control of the proliferation of monocytes/macrophages, even if these cells are classically described as devoided of any proliferative capacity.

Huntington's disease is due to the mutation of the IT15 gene coding for Huntingtin protein (Htt). This mutation leads to the expression of an abnormal repeat of polyglutamines in the N-terminal region of Htt. The pathophysiology of Huntington's disease remains to be elucidated. Various mechanisms have been proposed to account for neuronal dysfunction and death, and include both a gain of toxic function of the mutated Htt and a loss of function of the wild type Htt. Among these mechanisms, transcriptional dysregulation, mitochondrial dysfunction, increased excitotoxicity, as well as alteration of neuritic transport and synaptic transmission have been proposed. Interestingly, there is a prominent vulnerability of the striatal neurons, despite the ubiquitous expression of Htt. This may be due to the particular morphological and functional characteristics of these neurons, or to their location within the cerebral networks and the inputs they receive. As multiple mechanisms are involved in neuronal death, the use of drugs association should be considered in future neuroprotective therapeutic trials.

Decreased drug metabolism, hyperbilirubinemia and intrahepatic cholestasis are frequently observed during inflammation. Additionally, it has long been appreciated that exposure to drug metabolism-inducing xenobiotics can impair immune function. The nuclear receptor CAR (constitutive androstane receptor or NR1I3) and PXR (pregnane X receptor, NR1I2) control phase I (cytochrome P450 2B and 3A), phase II (GSTA, UGT1A1), and transporter (MDR1, SLC21A6, MRP2) genes involved in drugs metabolism, bile acids and bilirubin clearance in response to xenobiotics. It is well known that inflammation, through the activation of NF-kappaB pathway, leads to a decrease of CAR, PXR and RXRalpha expression and the expression of their target genes. In addition, a new study reveals the mutual repression between PXR and NF-kappaB signaling pathways, providing a molecular mechanism linking xenobiotic metabolism and inflammation.

Traditionally, mRNA decay was considered a simple destruction step of mRNA. This view has been challenged in the past years and mRNA decay now appears as an essential step in the regulation of gene expression. We first present a short review of the different reactions involved in mRNA decay, as well as some indications on their cellular location. Then, we describe two processes in which mRNA decay plays an essential role: (1) the mRNA quality control mechanisms that get rid of aberrant mRNAs (nonsensE-mediated decay, non-stop decay, no-go decay); (2) the regulation of mRNA stability through the targeting of specific factors to the mRNA (proteins or small non-coding RNAs).

The transcription factor NF-kappaB has a central role in coordinating the expression of a wide variety of genes that control the immune system. Defining the proteins and the mechanisms that transmit signals from the T-cell receptor to NF-kappaB is therefore an important goal for immunologists. Although most players have probably been identified, relatively little is known about the detailed molecular mechanisms involved in the cascade leading to NF-kappaB activation following engagement of the T cell receptor by a foreign antigen. PKCtheta, CARMA1, BCL-10, MALT1 and caspase 8 are signalling proteins that have a key role in antigen receptor-mediated lymphocyte activation through the NF-kappaB pathway. In this review, we discuss recent insights into this specific signal transduction cascade, and the way it is regulated. Several lines of evidence, mainly from biochemical studies of T cells clearly indicate that phosphorylation, ubiquitination and degradation are key control elements in the positive and negative regulation of the NF-kappaB pathway in response to TCR stimulation.

The ability to achieve site-specific correction or modification of the genome has widespread implications for basic and applied research. Individual zinc finger (ZF) domain recognizes DNA triplets with high specificity and affinity. They are used to create zinc finger protein (ZFP), like the ZF-nucleases, which could be designed to be specific for nearly any site in the genome. These domains can be tandemly linked to recognize DNA sequences of different lengths, with high fidelity. Different methods have been developed to design ZF specifically targeted to any triplet. This modular design offers a large number of combinatorial possibilities for the specific recognition of DNA. By fusing ZF to repression or activation domains, genes can be selectively targeted and switched off and on. Zinc-finger proteins (ZFPs) that recognize novel DNA sequences are the basis of a powerful technology platform with many uses in therapeutics. The ZF have been used as the DNA-binding domains of novel transcription factors (ZFP TFs) which are used to inhibit or activate genes involved in different diseases. ZF-nucleases are developed to modify genes implicated in different diseases. Many clinical trials using ZFPs are currently under investigation.

Glucose should not be considered uniquely as a cellular fuel but also as a signaling molecule involved in the regulation of genes encoding glycolytic and lipogenic enzymes and, as such, in storage of triglycerides. Transcriptional effects of glucose on glycolytic and lipogenic enzymes involve a specific transcription factor, ChREBP, whose characteristics and mechanism of activation are described. Finally, the possible implication of ChREBP in the physiopathology of obesity and type 2 diabetes are discussed.

Milk protein gene expression varies during the pregnancy/lactation cycle under the influence of lactogenic hormones which induce the activation of several transcription factors. Beyond this activation modifying the binding properties of these factors to their consensus sequences, their interactions with DNA is regulated by variations of the chromatin structure. In the nuclei of the mammary epithelial cell, the three dimensional organisation of the chromatin loops, located between matrix attachment regions, is now being studied. The main milk components are organised in supramolecular structures. Milk fat globules are made of a triglyceride core enwrapped by a tripartite membrane originating from various intracellular compartments. The caseins, the main milk proteins, form aggregates: the casein micelles. Their gradual aggregation in the secretory pathway is initiated as soon as from the endoplasmic reticulum. The mesostructures of the milk fat globule and of the casein micelle remain to be elucidated. Our goal is to make some progress into the understanding of the molecular and cellular mechanisms involved in the formation of these milk products.

Aging is associated with alterations of the circadian rhythms (shortened amplitude and phase-advance). We studied by quantitative RT-PCR the influence of aging on the expression of circadian clock genes (Clock, Bmal1, Cry1,2, Per1-3) in peripheral tissues (liver and heart) of middle-aged (13 months) and old (27 months) rats of the Wag/Rij strain exposed to a 12 hours light/12 hours dark cycle. Rats were killed at the light-dark transition (8 am and 8 pm). In the liver, Per, Cry et Bmal1 genes showed a morning/evening difference of expression; in addition, old rats exhibited a significant decrease of Per gene expression in the evening vs middle-aged rats. The heart showed similar profiles with only a tendency toward a decrease of Per expression and an increased Bmal1 expression in the evening in old rats. These results show that aging is associated with circadian gene expression changes.

The balance between production and degradation of type I collagen plays a critical role in the development and maintenance of organ and tissue integrity. Its also represents the most crucial element governing the process of tissue repair. TGF-beta, a key player in the physiopathology of tissue repair, enhances type I collagene gene expression. In contrast, TNF-alpha, whose matrix-remodelling function is opposite to that of TGF-beta, reduces type I collagen gene expression. This review focuses on transcriptional regulation of type I collagen by TGF-beta and TNF-alpha, and on the molecular mechanisms that control the antagonistic activity of TNF-alpha against TGF-beta-driven type I collagen gene expression.

E-cadherin is a cell adhesion molecule that is present in most normal epithelial cells. During malignant transformation, the expression of E-cadherin is frequently repressed. This protein is considered as a tumor-suppressor. The oncogenic form of Akt, a serine-threonine kinase, is multifunctionnal. One of its function is to induce the transcriptional repression of E-cadherin. This transcriptional repression induces cellular responses, epithelial cells becoming mesenchymal and invasive. At the molecular level, cells expressing a constitutive active form of Akt express also a transcription factor, Snail, known to repress the expression of E-cadherin.

Because the GnRH receptor plays a paramount role within the reproductive axis, the understanding of the molecular apparatus that governs the tissue-specific expression and regulation of this gene must lead to a better knowledge of the physiology and the physiopathology of the gonadotrope function. To elucidate these mechanisms, we have used two complementary in vivo and in vitro approaches. Firstly, we have isolated the pituitary promoter of the rat GnRH receptor gene and investigated its activity using transient transfection into two gonadotrope-derived cell lines, the alphaT3-1 and the LbetaT2 cell lines. We have thus defined a primary set of transcription factors involved in the tissue-specific expression of the GnRH receptor gene. These include the steroidogenic factor-1 (SF-1) which plays a decisive role while functionally interacting with proteins related to the GATA and LIM homeodomain families of transcription factors. In addition, we highlighted the critical implication of SF-1 and its functional interaction with a CREB-related factor in the stimulatory action of PACAP (Pituitary Adenylate Cyclase Activating Polypeptide) on promoter activity. These results have led us to analyze the activity of this promoter by transgenesis in the mouse using human placental alkaline phosphatase as a reporter gene. In agreement with the in vitro data, the pituitary promoter was found to confer gonadotrope-specific activity in the pituitary. It was also able to direct transgene expression in several areas of the central nervous system known to express the endogenous GnRH receptor, in particular in the hippocampo-septal complex. Some of these tissue do not express SF-1, suggesting that, in vivo, its role would not be as decisive as suggested by the in vitro experiments. Surprisingly, during pituitary ontogenesis, the transgene is expressed as early as E 13.5 whereas SF-1 is not yet present in the pituitary. Thus, in vivo, SF-1 would not be necessary for the activation of the GnRH receptor gene during the early developmental stages in the pituitary. These results are consistent with data obtained following general or pituitary-specific knockout of the gene encoding SF-1, suggesting that the GnRH receptor is expressed despite the absence of this factor. Identifying the factors responsible for the activation of the GnRH receptor gene at these early developmental stages should make it possible to refine the role of SF-1, not only in gene regulation but more generally, in the physiology and the physiopathology of the gonadotrope function.

Glycemia is a physiological parameter tightly regulated for an optimal energetic supply to the organism, in spite of variable tissular glucose needs. Physiopathological alteration of glycemic regulation leads to dysfunctions of many cell types. For example, diabetes considerably increases morbidity and mortality linked to cardiovascular pathologies and constitute nowadays a serious public health problem. Many in vivo and in vitro studies have investigated the impact of extracellular glucose concentration on smooth muscle and endothelial cells. Glycemia regulates expression and activity of proteins implicated in various processes, such as vasodilation (eNOS), cellular adherence (ICAM-1, VCAM-1), glucose transport (GLUT-1) or free radical generation. Nuclear receptors of the PPAR (peroxisome proliferator-activated receptors) family which are implicated in glucose and lipid metabolism control, seem to have direct vascular actions, in the regulation of cellular functions by extracellular glucose, reinforcing their status of pharmacological targets for preservation and improvement of vascular function. More general processes, such as cellular proliferation and cell death, are also influenced by glucose concentration. Concerning the contractile function, hypoglycemia and hyperglycemia modulate vascular reactivity while acting on the vasoactive substances level and the cellular response to these molecules. In particular they act on variation of ionic channels (K+, Ca2+) activity or by interfering with some signaling pathways (NO). For example, the age-dependant vasodilation and endothelial calcium influx induced by elastin peptide are modulated by extracellular glucose levels. In conclusion, abnormal chronic variations of circulating glucose levels seem to be directly responsible for endothelial and smooth muscle cell dysfunction in the pathogenesis of cardiovascular abnormalities of patients presenting glycemia dysregulations.

A major goal of chronobiology is to identify clock-controlled genes. The expression of thousands of genes can be monitored simultaneously using DNA microarrays. Application of DNA microarray technology to the field of circadian rhythm has already shown that a number of genes coding for proteins involved in very diverse functions are under the control of the circadian clock.

Androgens play a crucial role in the development, maintenance and regulation of male phenotype and reproductive physiology through the androgen receptor, a transcription factor. Testosterone or dihydrotestosterone binding induces a trans-conformation of the androgen receptor and allows its translocation into the nucleus, where it recognizes specific DNA sequences. Recent developments in molecular genetics, as well as structural analysis of the androgen receptor, allow a better understanding of the structure/function relationship of this nuclear receptor. Molecular analyses of androgen insensitivity syndrome, as well as hormone-resistant prostate cancer, Kennedy's disease and isolated male infertility, have been proved useful as privileged models for this purpose. In the absence of identified AR receptor mutations in androgen insensitivity syndromes, abnormalities of transcriptional cofactor should be considered. Finally, identification of androgen-dependent genes will be helpful for evaluating the degree of the molecular defect of androgen action within target cells.

Whole genome" expression profiles can be used as molecular signatures or portraits characteristic of a tumour or of the physiological state of a cell. This global description also provides a new approach for the study of the transcriptional regulation, and this review is dedicated to this fundamental aspect of the transcriptome. Gene expression studies will be first considered at the single cell level. In situ analyses reveal that transcription is a stochastic phenomenon, indicating that the transcriptome contains fluctuating regions. The transcriptional response of a cell population to an external stimulus has been used to evaluate the contribution of the various signalling pathways and transcription factors. One of the emerging themes is the co-ordinate expression of genes associated with the same physiological process. In the spirit of this analysis of the transcriptional regulatory networks, it is becoming possible to design artificial biological networks to implement desired functions, paving the way to new therapeutic approaches.

Objectives: To determine the viability and differentiation of human hepatocytes immunoprotected by encapsulation and transplanted in rats without immunosuppression., Methods: Freshly isolated human hepatocytes were encapsulated in hollow fibers and transplanted in the peritoneal cavity of immunocompetent rats. The fibers were explanted for analysis at D3, D7 and D14 following transplantation. Morphological features under light and electron microscopy and gene expression were compared to those of non-transplanted encapsulated hepatocytes (D0). Human cytochrome P450 3A and albumin mRNAs were quantified by Northern blot. Cytochrome P450 3A proteins were detected by Western blot and cytochrome P450 3A enzyme activity was assessed by measuring the formation of 6beta-hydroxytestosterone by high performance liquid chromatography., Results: Transplanted hepatocytes were more than 60 % viable and exhibited morphological criteria of hepatocytic differentiation up to D7. Albumin and cytochrome P450 3A transcripts were also detected up to D14. At D3 and D7, albumin mRNA levels were of 30 %, compared to control D0 hepatocytes, while cytochrome P450 3A5 and cytochrome P450 3A4 mRNA levels were 65 % and 0 %, respectively. Cytochrome P450 3A immunoreactivity was detected by Western blot up to D14 and 6beta-hydroxylase activity was 17 % at D3 compared to D0, supporting with disappearance of cytochrome P450 3A4 mRNA., Conclusions: Human hepatocytes remain viable for a short period, following encapsulation and intraperitoneal transplantation in rat. Other experimental conditions need to be tested to prevent or delay a decrease in hepatocyte specific gene expression.

Fibrates are old hypolipidemic drugs with pleitropic effects on lipid metabolism. Until, recently their intimate molecular mechanisms of action were mysterious. In the late 5 years, we have shown that the pharmacological effects of fibrates depend on their binding to "Peroxisome Proliferator Activated Receptor alpha" (PPAR alpha). The binding of fibrates to PPAR alpha induces the activation or the inhibition of multiple genes involved in lipid metabolism through the binding of the activated PPAR alpha to "Peroxisome Proliferator Response Element" (PPRE) located in the gene promoters. Fibrates reduce plasma triglyceride levels by altering the expression of numerous genes coding for proteins involved in fatty acid metabolism (fatty acid transport protein, acyl-CoA synthetase, etc.) and also by increasing the lipoprotein lipase synthesis and decreasing the apolipoprotein C-III synthesis. Fibrates increase HDL cholesterol levels by increasing apolipoprotein A-I and apolipoprotein A-II synthesis. Furthermore, we recently demonstrated that fibrates are potent anti-inflammatory molecules through an indirect modulation of the nuclear-factor-kappa B activity. Therefore, we suggest that fibrates inhibit atherosclerosis development not only by improving the plasma lipid profile but also by reducing inflammation in the vascular wall.

Introduction: The transcription factor NF-kappa B is a key regulator of genes involved in responses to infection, inflammation and stress. It was first identified as a protein with ADN-binding activity specific for the 10-base-pair kappa B site in the immunoglobulin k light-chain enhancer of B lymphocytes., Current Knowledge and Key Points: NF-kappa B is normally present in the cell cytoplasm bound to an inhibitory I kappa B protein. The nuclear localization signal (NLS) in NF-kappa B is a short amino acid signal sequence involved in nuclear transport. Inducers of NF-kappa activation trigger dissociation and degradation of I kappa B from the NF-kappa B complex. This allows NF-kappa B to translocate to the nucleus and bind to kappa B DNA sites. Repression of NF-kappa B dependent gene expression is one of the major elements of immunosuppression by glucocorticoids. FUTURES PROSPECTS AND PROJECTS: Endothelial cells at sites of inflammatory responses express a variety of genes that are under the control of nuclear factor NF-kappa B. This transcriptional factor with its inhibitors may be linked in an autoregulatory system that can be activated by multiple signals relevant to vascular pathophysiology. NF-kappa B is therefore an obvious target for new types of anti-inflammatory treatment.

Traditionally, the screening of new neuropsychotropic agents started from the observation of behavioural effects resulting from the administration of a new chemical. Then, one tried to precise its mechanism of action. Since about a decade the way for discovering psychotropic agents tends to be inverse. It starts from the characterization of genes and investigates on their expression products which are new biological targets. Ligands for these targets are developed and then the effects resulting from their administration are considered. In this new strategy, we will consider the cloning of genes and their expression in cultured cells; the knock out of these genes by homologous recombination; the extinction of gene expression by antisense oligodeoxynucleotides; the concentration of behavioural phenotypes by selective breeding.

Chronic depression actually covers several different nosographic entities. Among the predictive factors for chronicity, personality disorders raise the complex issue of the relationship between traits and depression. Some approaches favour the concept of premorbid personality, others in contrast insist more on personality disorders which complicate a depressive episode. In order to account for both stress factors and biological factors in the progression of depression towards chronicity, Post suggested in 1992 a bold integrative pattern. In this pattern, the premorbid period would be marked by secondary sensitization to repeated stress factors. These factors would cause not only short-term but also longer-term fragility by modifying the transcription of protein encoding, in particular for the C-fos oncogene. This would cause peptide alterations which originate a vulnerability to mood disorders. With time, an accumulation mechanism and a kindling phenomenon would cause the initial depressive episode to develop, and that in turn would constitute a new vulnerability factor for the new spontaneous occurrence of further depressive episodes. This model has the merit to underline the importance of early and durable treatment. It also suggests a promising approach for the future.

The identification of the viral oncogene v-erbA carried by an avian leukemia retrovirus has directly demonstrated the involvement of hormone receptors in neoplastic transformation. v-erbA represents an altered form of a nuclear receptor of the thyroid hormone T3. It blocks the differentiation of chicken erythrocyte progenitor cells and contributes to sarcoma transformation in association with other oncogenes. The protein encoded by v-erbA behaves as an antagonist against the normal T3 receptors and retinoic acid receptors. The primary effects of the protein result in altering the transcription of genes normally under control of the intact receptors. Presumably among these target genes are to be found genes which control cell differentiation and proliferation.

Genetic alterations in solid human tumors occur in several groups of genes, one of which contains the proto-oncogenes. These genes are involved in the control of cell proliferation and become activated in oncogenes by various mechanisms. These activations are reviewed herein.