Contributions of peroxisome proliferator-activated receptor β/δ to skin health and disease

Among the three peroxisome proliferator-activated receptor (PPAR) transcription factors, PPARβ/δ is the isotype with the broadest expression pattern. In fact, the expression of PPARβ/δ is ubiquitous, albeit at levels that are tightly regulated. Herein, we reviewed its multiple functions in skin health and disease. PPARβ/δ has pro-differentiating effects in keratinocytes, regulates sebocyte differentiation, and promotes hair follicle growth in healthy skin. Furthermore, we reviewed novel insights into the roles of PPARβ/δ in skin wound healing, especially in inhibiting apoptosis and in modulating keratinocyte proliferation and migration. Therefore, PPARβ/δ represents a research target for the understanding and treatment of inflammatory skin diseases, such as psoriasis and acne vulgaris. In addition, PPARβ/δ is a tumor growth modifier. Epidemiological studies have established that tumor progression may be exacerbated by chronic low-grade inflammation, a condition promoting the production of the lipids that act as modulators of PPARβ/δ activity. The action of PPARβ/δ in skin cancer is ambivalent, which might be explained by this receptor's putative highly context-specific behavior, which depends on a combination of factors ranging from receptor expression levels to co-regulator distribution, diversity and activity of the ligands produced, and other tissue-specific conditions. Given its diverse and crucial roles in many tissues and organs, PPARβ/δ will remain a major focus of future researc

Peroxisome proliferator-activated receptor β/δ: a master regulator of metabolic pathways in skeletal muscle

Skeletal muscle is considered to be a major site of energy expenditure and thus is important in regulating events affecting metabolic disorders. Over the years, both in vitro and in vivo approaches have established the role of peroxisome proliferator-activated receptor-β/δ (PPARβ/δ) in fatty acid metabolism and energy expenditure in skeletal muscles. Pharmacological activation of PPARβ/δ by specific ligands regulates the expression of genes involved in lipid use, triglyceride hydrolysis, fatty acid oxidation, energy expenditure, and lipid efflux in muscles, in turn resulting in decreased body fat mass and enhanced insulin sensitivity. Both the lipid-lowering and the anti-diabetic effects exerted by the induction of PPARβ/δ result in the amelioration of symptoms of metabolic disorders. This review summarizes the action of PPARβ/δ activation in energy metabolism in skeletal muscles and also highlights the unexplored pathways in which it might have potential effects in the context of muscular disorders. Numerous preclinical studies have identified PPARβ/δ as a probable potential target for therapeutic interventions. Although PPARβ/δ agonists have not yet reached the market, several are presently being investigated in clinical trial

Intégration des TIC dans une classe d’enseignement spécialisé: Utilisation d’iPads avec des adolescents en échec scolaire et en difficulté sociale dans une classe du Centre Educatif et Pédagogique de Courtelary, baignant déjà dans une culture « ordinateurs ». Quels effets sur leur motivation ?

Ce travail s’inscrit dans le cadre de l’enseignement spécialisé, plus précisément dans une classe à effectif réduit, qui peut être considérée, selon Curonici, Joliat et McCulloch (2011) comme un lieu de changement à effet « émotionnellement correcteur » (p.241). Les élèves, adolescents fragilisés par leur parcours et dont souvent le processus d’apprentissage stagne, ont besoin d’une relation élève-enseignant complémentaire, basée sur la différence. Pour l’enseignant, cela ne signifie pas forcément leur donner « plus », mais reconnaître le mal-être et la mauvaise estime de l’élève pour ensuite avoir « l’art de développer le plaisir d’apprendre ». « Les plus grands moteurs de l’apprentissage sont le plaisir, les émotions positives, la motivation » (Fourgous, 2012, p.8). Cette recherche s’efforce de mettre en lumière l’utilisation des TIC, plus particulièrement des iPads, afin de mieux comprendre si ces outils favorisent la motivation des apprenants, en s’appuyant sur un cadre de référence proposé par Viau (2009) et basé sur une approche sociocognitive : cela permet « d’éviter deux écueils opposés : considérer que la motivation relève exclusivement de facteurs internes à l’apprenant ou au contraire qu’elle relève uniquement de facteurs externes à l’apprenant » (Galant et Bourgeois, 2006, cités par Viau, 2009, p.195)

PPARs Mediate Lipid Signaling in Inflammation and Cancer

Lipid mediators can trigger physiological responses by activating nuclear hormone receptors, such as the peroxisome proliferator-activated receptors (PPARs). PPARs, in turn, control the expression of networks of genes encoding proteins involved in all aspects of lipid metabolism. In addition, PPARs are tumor growth modifiers, via the regulation of cancer cell apoptosis, proliferation, and differentiation, and through their action on the tumor cell environment, namely, angiogenesis, inflammation, and immune cell functions. Epidemiological studies have established that tumor progression may be exacerbated by chronic inflammation. Here, we describe the production of the lipids that act as activators of PPARs, and we review the roles of these receptors in inflammation and cancer. Finally, we consider emerging strategies for therapeutic intervention

Peroxisome Proliferator-Activated Receptors as Molecular Links between Caloric Restriction and Circadian Rhythm.

The circadian rhythm plays a chief role in the adaptation of all bodily processes to internal and environmental changes on the daily basis. Next to light/dark phases, feeding patterns constitute the most essential element entraining daily oscillations, and therefore, timely and appropriate restrictive diets have a great capacity to restore the circadian rhythm. One of the restrictive nutritional approaches, caloric restriction (CR) achieves stunning results in extending health span and life span via coordinated changes in multiple biological functions from the molecular, cellular, to the whole-body levels. The main molecular pathways affected by CR include mTOR, insulin signaling, AMPK, and sirtuins. Members of the family of nuclear receptors, the three peroxisome proliferator-activated receptors (PPARs), PPARα, PPARβ/δ, and PPARγ take part in the modulation of these pathways. In this non-systematic review, we describe the molecular interconnection between circadian rhythm, CR-associated pathways, and PPARs. Further, we identify a link between circadian rhythm and the outcomes of CR on the whole-body level including oxidative stress, inflammation, and aging. Since PPARs contribute to many changes triggered by CR, we discuss the potential involvement of PPARs in bridging CR and circadian rhythm

PPARs and Microbiota in Skeletal Muscle Health and Wasting.

Skeletal muscle is a major metabolic organ that uses mostly glucose and lipids for energy production and has the capacity to remodel itself in response to exercise and fasting. Skeletal muscle wasting occurs in many diseases and during aging. Muscle wasting is often accompanied by chronic low-grade inflammation associated to inter- and intra-muscular fat deposition. During aging, muscle wasting is advanced due to increased movement disorders, as a result of restricted physical exercise, frailty, and the pain associated with arthritis. Muscle atrophy is characterized by increased protein degradation, where the ubiquitin-proteasomal and autophagy-lysosomal pathways, atrogenes, and growth factor signaling all play an important role. Peroxisome proliferator-activated receptors (PPARs) are members of the nuclear receptor family of transcription factors, which are activated by fatty acids and their derivatives. PPARs regulate genes that are involved in development, metabolism, inflammation, and many cellular processes in different organs. PPARs are also expressed in muscle and exert pleiotropic specialized responses upon activation by their ligands. There are three PPAR isotypes, viz., PPARα, -β/δ, and -γ. The expression of PPARα is high in tissues with effective fatty acid catabolism, including skeletal muscle. PPARβ/δ is expressed more ubiquitously and is the predominant isotype in skeletal muscle. It is involved in energy metabolism, mitochondrial biogenesis, and fiber-type switching. The expression of PPARγ is high in adipocytes, but it is also implicated in lipid deposition in muscle and other organs. Collectively, all three PPAR isotypes have a major impact on muscle homeostasis either directly or indirectly. Furthermore, reciprocal interactions have been found between PPARs and the gut microbiota along the gut-muscle axis in both health and disease. Herein, we review functions of PPARs in skeletal muscle and their interaction with the gut microbiota in the context of muscle wasting

Geographic distribution of Tetracapsuloidesbryosalmonae infected fish in Swiss rivers: an update

Abstract.: Proliferative kidney disease (PKD) has been recognized as a potential threat to brown trout (Salmotrutta) populations in Switzerland. A study performed in 2000/2001 on 139 sampling sites from 127 rivers in Switzerland revealed a wide distribution of fish infected by Tetracapsuloidesbryosalmonae, the causative agent of PKD. The present study aimed to complement this dataset by studying a further 115 sample sites from 91 rivers and 4 fish farms. Mainly brown trout were investigated for the presence of T. bryosalmonae by a combination of macroscopical, histological and immunohistochemical examination. In approximately 56% of the examined sampling sites, T. bryosalmonae-infected fish were found. The prevalence of infected fish at individual sites ranged from 0% to 100%. Infection intensity, judged on the basis of histological and immunohistochemical evaluation for the degree of parasite infection, varied greatly between and within sites. PKD-positive sites were found in all areas of Switzerland. The wide distribution of the disease in Swiss rivers indicates that PKD may be a causative factor for the catch decline of brown trout, which was suggested over recent decades in Switzerlan

Functions of peroxisome proliferator-activated receptors (PPAR) in skin homeostasis

The peroxisome proliferator-activated receptors (PPAR) are ligand-activated transcription factors that belong to the nuclear hormone receptor family. Three isotypes (PPARα, PPARβ or δ, and PPARγ) with distinct tissue distributions and cellular functions have been found in vertebrates. All three PPAR isotypes are expressed in rodent and human skin. They were initially investigated for a possible function in the establishment of the permeability barrier in skin because of their known function in lipid metabolism in other cell types. In vitro studies using specific PPAR agonists and in vivo gene disruption approaches in mice indeed suggest an important contribution of PPARα in the formation of the epidermal barrier and in sebocyte differentiation. The PPARγ isotype plays a role in stimulating sebocyte development and lipogenesis, but does not appear to contribute to epidermal tissue differentiation. The third isotype, PPARβ, regulates the late stages of sebaceous cell differentiation, and is the most effective isotype in stimulating lipid production in these cells, both in rodents and in humans. In addition, PPARβ activation has pro-differentiating effects in kera-tinocytes under normal and inflammatory conditions. Finally, preliminary studies also point to a potential role of PPAR in hair follicle growth and in melanocyte differentiation. By their diverse biological effects on cell proliferation and differentiation in the skin, PPAR agonists or antagonists may offer interesting oppotunities for the treatment of various skin disorders characterized by inflammation, cell hyperproliferation, and aberrant differentiatio

Eine ruhige Jacke, portrait d’un silence bruyant

« Je suis maintenant enfermé dans la boîteet la vie suit son cours ennuyeux. »Roman, le 28 novembre 2008 L’ambition du « genre » documentaire est de présenter un morceau spécifique de réalité, de le dévoiler d’une façon particulière. Que se passe-t-il dès lors que la part de réel que l’on a choisi de projeter sur la toile n’est autre que l’un de nos semblables, lorsque le sujet est un Sujet ? C’est ce que choisit de montrer le premier assemblage d’images du jeune réalisateur suisse alémanique..