The mitogen-activated protein kinase kinase kinase dual leucine zipper-bearing kinase (DLK) acts as a key regulator of keratinocyte terminal differentiation.

In the skin, epithelial cells undergo a terminal differentiation program leading to the formation of the stratum corneum. Although it is expected that the last phases of this process must be tightly regulated since it results in cell death, the signaling pathways involved in this induction remain ill defined. We now report that a single kinase, the mitogen-activated protein kinase kinase kinase dual leucine zipper-bearing kinase (DLK), acts in the epidermis to promote the terminal differentiation of human keratinocytes. In support of this notion, we showed that DLK expression was restricted to the granular layer in situ. In addition, cultured keratinocytes infected with a recombinant adenovirus expressing DLK exhibited morphological and biochemical changes, including a suprabasal localization, altered cell shape, compacted cytoplasm, DNA fragmentation, and the up-regulation of filaggrin, that are reminiscent of a terminally differentiated phenotype. Moreover the expression of wild-type DLK in keratinocytes stimulated transglutaminase activity and the consequent formation of the cornified cell envelope, while a kinase-inactive variant of DLK did not. Together these results identify DLK as a signaling molecule implicated in the regulation of keratinocyte terminal differentiation and cornification

Fabrication of poly-3-hexylthiophene/polyethylene oxide nanofibers using electrospinning

Peer reviewed: YesNRC publication: Ye

Fabrication of highly conductive PEDOT nanofibers

NRC publication: Ye

Highly conductive PEDOT nanofibers obtained by combination of electrospinning and vapour-phase polymerization

Peer reviewed: YesNRC publication: Ye

Nano and Micro Fibers for Conductive Applications

Peer reviewed: YesNRC publication: Ye

Strategies for the Fabrication and Characterization of Conductive Fibers Using Electrospinning and Melt-spinning Techniques

Peer reviewed: YesNRC publication: Ye

Development of conductive polymeric fibers for flexible electronics applications

Conductive micro and nanofibers have been produced by melt-spinning and electrospinning. Melt-spinning uses mechanical forces to stretch fibers while electrospinning allows the production of fibers using the force of an electric field to stretch them. Alternatively, textile multifilament fibers were coated with intrinsically conducting polymers (ICPs). The fibers were characterized by electron microscopy (SEM, TEM) as well as 4-point probe conductivity measurements.On a produit des nanofibres et des microfibres conductrices par filage par fusion et par \ue9lectrofilature. Le filage par fusion fonctionne gr\ue2ce \ue0 des forces m\ue9caniques pour \ue9tirer les fibres, alors que l\u2019\ue9lectrofilature permet la production de fibres gr\ue2ce \ue0 la force d\u2019un champ \ue9lectrique qui les \ue9tire. Autrement, des fibres textiles multifilaments ont \ue9t\ue9 recouvertes de polym\ue8res intrins\ue8quement conducteurs. Les fibres ont \ue9t\ue9 caract\ue9ris\ue9es par microscopie \ue9lectronique (MEB, MET), ainsi qu\u2019au moyen de mesures de conductivit\ue9 avec une sonde \ue0 quatre points.Peer reviewed: YesNRC publication: Ye

The Mixed Lineage Kinase Leucine-Zipper Protein Kinase Exhibits a Differentiation-Associated Localization in Normal Human Skin and Induces Keratinocyte Differentiation upon Overexpression

Leucine-zipper protein kinase/dual leucine zipper bearing kinase/mitogen-activated protein kinase-upstream kinase is a recently described protein serine/threonine kinase which belongs to the mixed lineage kinase family. The overall pattern of expression of the leucine-zipper protein kinase/dual leucine zipper bearing kinase/mitogen-activated protein kinase-upstream kinase gene in embryonic and adult mouse tissues suggested that this kinase could be involved in the regulation of epithelial cell proliferation and differentiation. In order to get more insights into the potential role of leucine-zipper protein kinase in these cellular processes, we characterized its expression in normal human skin, both at the mRNA and protein levels. In situ hybridization, western blotting, and indirect immunofluorescence studies were conducted to localize leucine-zipper protein kinase on various human skin tissues. This is one of the first reports that leucine-zipper protein kinase has a very precise pattern of expression in human skin epithelia, as both mRNA and protein are restricted to the granular layer of the epidermis and inner root sheath of hair follicles. Detection of leucine-zipper protein kinase protein on skin from various body sites, donors of different ages as well as on reconstructed human skin always reveals that leucine-zipper protein kinase is present only in the very differentiated keratinocytes of epidermis and hair follicles. To determine directly whether leucine-zipper protein kinase exhibits any effect on cell growth and differentiation, keratinocytes were transfected with an expression vector harboring the leucine-zipper protein kinase cDNA. The presence of this construct in keratinocytes results in growth arrest together with a concomitant increase in filaggrin expression. Collectively, our results indicate that leucine-zipper protein kinase plays an active part in cellular processes related to terminal differentiation of epidermal keratinocytes

Preparation of Hybrid Proton Exchange Membranes Based on HPA/Clay Complexes and Thermoplastic Polymers

Peer reviewed: YesNRC publication: Ye

Fabrication of proton exchange membranes using melt processing technologies

Peer reviewed: YesNRC publication: Ye