In human skin, melanogenesis is a tightly regulated process. Indeed, several extracellular signals are transduced via dedicated signalling pathways and mostly converge to MITF, a transcription factor ...integrating upstream signalling and regulating downstream genes involved in the various inherent mechanisms modulating melanogenesis. The synthesis of melanin pigments occurs in melanocytes inside melanosomes where melanogenic enzymes (tyrosinase and related proteins) are addressed with the help of specific protein complexes. The melanosomes loaded with melanin are then transferred to keratinocytes. A more elaborate level of melanogenesis regulation comes into play via the action of non‐coding RNAs (microRNAs, lncRNAs). Besides this canonical regulation, melanogenesis can also be modulated by other non‐specific intrinsic pathways (hormonal environment, inflammation) and by extrinsic factors (solar irradiation such as ultraviolet irradiation, environmental pollution). We developed a bioinformatic interaction network gathering the multiple aspects of melanogenesis and skin pigmentation as a resource to better understand and study skin pigmentation biology.
Résumé
Dans la peau humaine, le processus de la mélanogenèse est extrêmement contrôlé. En effet, divers signaux extracellulaires sont transduits via des voies de signalisation dédiées qui convergent essentiellement vers le facteur de transcription MITF. Ce dernier intègre cette signalisation en amont et régule alors la transcription de gènes impliqués dans les divers mécanismes inhérents à la modulation de la mélanogenèse. La synthèse des pigments de mélanine se produit dans les mélanocytes, à l'intérieur des mélanosomes dans lesquels les enzymes de la mélanogenèse (tyrosinase et protéines apparentées) sont adressées à l'aide de complexes protéiques spécifiques. Les mélanosomes ainsi chargés en mélanine sont ensuite transférés aux kératinocytes. Un niveau plus élaboré de régulation de la mélanogenèse entre aussi en jeu au travers de l'action d’ARNs non codants (microARNs et lncRNAs). Outre cette régulation canonique, la mélanogenèse peut également être modulée par des voies intrinsèques non spécifiques telles l'environnement hormonal et l'inflammation, et par des facteurs extrinsèques, comme le rayonnement solaire et la pollution environnementale. Nous avons par ailleurs développé un réseau d'interactions gènes/protéines regroupant les multiples aspects de la régulation de la mélanogenèse et de la pigmentation de la peau grâce à l'outil bioinformatique. Ce réseau constitue une ressource pour mieux comprendre et étudier la biologie de la pigmentation de la peau.
Stem cells capable of differentiating to multiple lineages may be valuable for therapy. We report the isolation of human and rodent amniotic fluid-derived stem (AFS) cells that express embryonic and ...adult stem cell markers. Undifferentiated AFS cells expand extensively without feeders, double in 36 h and are not tumorigenic. Lines maintained for over 250 population doublings retained long telomeres and a normal karyotype. AFS cells are broadly multipotent. Clonal human lines verified by retroviral marking were induced to differentiate into cell types representing each embryonic germ layer, including cells of adipogenic, osteogenic, myogenic, endothelial, neuronal and hepatic lineages. Examples of differentiated cells derived from human AFS cells and displaying specialized functions include neuronal lineage cells secreting the neurotransmitter L-glutamate or expressing G-protein-gated inwardly rectifying potassium channels, hepatic lineage cells producing urea, and osteogenic lineage cells forming tissue-engineered bone.
Adsorption and release of the biologically active nitric oxide (NO) was evaluated over a series of highly flexible iron(III) dicarboxylate MOFs of the MIL-88 structure type, bearing fumaric or ...terephthalic spacer functionalized or not by polar groups (NO2, 2OH). As evidenced by ex situ X-ray powder diffraction and in situ IR spectroscopy, it appears that if the contracted dried forms of MIL-88 do not expand their structures in the presence of NO, the combination of very narrow pores and trimers of iron polyhedra leads to the adsorption of significant amounts of NO either physisorbed (very narrow pores) and/or chemisorbed iron(II) or iron(III) coordinatively unsaturated metal sites (CUS). The delivery of NO under vapor of water or in simulated body fluid does not exceed 20% range of the total adsorbed amount probably due to a partial release that occurs between the adsorption/desorption setup and the chemiluminescence release tests. Some of these solids nevertheless exhibit a significant release at the biological levels over a long period of time (>16 h) that make these biocompatible and biodegradable MOFs of interest for the controlled release of NO.
The chromium terephthalate MIL‐101 has been prepared rapidly and efficiently by using microwave‐assisted hydrothermal synthesis. The resulting material exhibits giant pores and very large surface ...areas and demonstrates a huge, rapid adsorption of benzene in both vapor (see figure) and liquid phases.
Highlights • Five weeks of high-fat diet (HFD) intake increases anxiety in female C57BL/6 mice. • Short-term object recognition memory is intact after 5 weeks of HFD intake. • Six-week HFD intake ...alters prefrontocortical/ventral hippocampal (vHIP) monoamines. • Eleven to twelve weeks of HFD consumption reduces synaptic plasticity in the vHIP. • Overall, HFD intake alters specific behaviors and linked monoamines in female mice.
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This contribution reports the fabrication and characterization of ultrathin films of nanoparticles of the water stable microporous Al tricarboxylate metal organic framework ...MIL-96(Al). The preparation of MOF dispersions in chloroform has been optimized to obtain dense monolayer films of good quality, without nanoparticle agglomeration, at the air-water interface that can be deposited onto solid substrates of different nature without any previous substrate functionalization. The MOF studied shows great interest for CO2 capture because it presents Al3+ Lewis centers and hydroxyl groups that strongly interact with CO2 molecules. A comparative CO2 adsorption study on drop-cast, Langmuir-Blodgett (LB) and Langmuir-Schaefer (LS) films using a Quartz Crystal Microbalance-based setup (QCM) has revealed that the CO2 uptake depends strongly on the film fabrication procedure and the storage conditions. Noteworthy the CO2 adsorption capacity of LB films is increased by 30% using a simple and green treatment (immersion of the film into water during 12 h just after film preparation). Finally, the stability of LB MOF monolayers upon several CO2 adsorption/desorption cycles has been demonstrated, showing that CO2 can be easily desorbed from the films at 303 K by flowing an inert gas (He). These results show that MOF LB monolayers can be of great interest for the development of MOF-based devices that require the use of very small MOF quantities, especially gas sensors.
A novel biocompatible and bioactive Metal-Organic Framework (BioMOF), named BioMIL-5 (Bioactive Materials from Institut Lavoisier), was hydrothermally synthesized from a Zn super(2+) salt and azelaic ...acid, both with interesting antibacterial and dermatological properties. Its structure was determined by high resolution X-ray powder diffraction, and further characterized by infrared spectroscopy, thermogravimetric analysis and elemental analysis. The determination of the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) values of BioMIL-5 in Staphylococcus aureusand Staphylococcus epidermidisdemonstrated that the antimicrobial activity of the individual components of BioMIL-5 were maintained after its synthesis. Moreover, BioMIL-5 was found to be stable in water and in bacterial culture medium, especially in water, leading to the subsequent progressive release of its active constituents, AzA and Zn super(2+) ions. Interestingly, this slow active delivery allowed control of the growth of a S. epidermidissuspension over 7 days. The high stability of this material and the maintenance of its antibacterial properties make BioMIL-5 a good candidate for future bioapplications, for skin care and in cosmetics.
Plant roots navigate in the soil environment following the gravity vector. Cell divisions in the meristem and rapid cell growth in the elongation zone propel the root tips through the soil. Actively ...elongating cells acidify their apoplast to enable cell wall extension by the activity of plasma membrane AHA H
-ATPases. The phytohormone auxin, central regulator of gravitropic response and root development, inhibits root cell growth, likely by rising the pH of the apoplast. However, the role of auxin in the regulation of the apoplastic pH gradient along the root tip is unclear. Here, we show, by using an improved method for visualization and quantification of root surface pH, that the
root surface pH shows distinct acidic and alkaline zones, which are not primarily determined by the activity of AHA H
-ATPases. Instead, the distinct domain of alkaline pH in the root transition zone is controlled by a rapid auxin response module, consisting of the AUX1 auxin influx carrier, the AFB1 auxin co-receptor, and the CNCG14 calcium channel. We demonstrate that the rapid auxin response pathway is required for an efficient navigation of the root tip.
The unusual adsorption behavior of CO2 in a nanoporous hybrid metal– organic solid is discussed (see figure). The results indicate that the gas adsorption–desorption step is related to a breathing ...phenomenon. This study also suggests that the main interactions responsible for the breathing phenomenon are strong guest–framework CO2–OH interactions as well as CO2–CO2 interactions along the tunnels present in the structure.
Nanoparticles made of metal-organic frameworks (nanoMOFs) attract a growing interest in gas storage, separation, catalysis, sensing and more recently, biomedicine. Achieving stable, versatile ...coatings on highly porous nanoMOFs without altering their ability to adsorb molecules of interest represents today a major challenge. Here we bring the proof of concept that the outer surface of porous nanoMOFs can be specifically functionalized in a rapid, biofriendly and non-covalent manner, leading to stable and versatile coatings. Cyclodextrin molecules bearing strong iron complexing groups (phosphates) were firmly anchored to the nanoMOFs' surface, within only a few minutes, simply by incubation with aqueous nanoMOF suspensions. The coating procedure did not affect the nanoMOF porosity, crystallinity, adsorption and release abilities. The stable cyclodextrin-based coating was further functionalized with: i) targeting moieties to increase the nanoMOF interaction with specific receptors and ii) poly(ethylene glycol) chains to escape the immune system. These results pave the way towards the design of surface-engineered nanoMOFs of interest for applications in the field of targeted drug delivery, catalysis, separation and sensing.
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