Biosynthesis of Wdr16, a marker protein for kinocilia-bearing cells, starts at the time of kinocilia formation in rat, and wdr16 gene knockdown causes hydrocephalus in zebrafish.

The rat ortholog of the WD40 repeat protein Wdr16 is abundantly expressed in testis and cultured ependymal cells. Low levels are found in lung and brain, respectively, while it is absent from kinocilia-free tissues. In testis and ependymal primary cultures, Wdr16 messenger RNA appears concomitantly with the messages for sperm-associated antigen 6, a kinocilia marker, and for hydin, a protein linked to ciliary function and hydrocephalus. In testis, ependyma and respiratory epithelium, the Wdr16 protein is up-regulated together with kinocilia formation. The wdr16 gene is restricted to genera in possession of kinocilia, and it is strongly conserved during evolution. The human and zebrafish proteins are identical in 62% of their aligned amino acids. On the message level, the zebrafish Wdr16 ortholog was found exclusively in kinocilia-bearing tissues by in situ hybridisation. Gene knockdown in zebrafish embryos by antisense morpholino injection resulted in severe hydrocephalus formation with unaltered ependymal morphology or ciliary beat. Wdr16 can be considered a differentiation marker of kinocilia-bearing cells. In the brain, it appears to be functionally related to water homeostasis or osmoregulation.

Regulation by insulin and insulin-like growth factor of 2-deoxyglucose uptake in primary ependymal cell cultures.

Ependymal cells have been reported to express the facilitative glucose carriers GLUT1, GLUT2, and GLUT4, as well as glucokinase. They are therefore speculated to be part of the cerebral glucose sensing system and may also respond to insulin with alterations in their glucose uptake rate. A cell culture model was employed to study the functional status of ependymal insulin-regulated glucose uptake in vitro. Insulin increased the uptake of the model substrate 2-deoxyglucose (2-DG) dependent on the insulin concentration. This was due to a near doubling of the maximal 2-DG uptake rate. Insulin-like growth factor (IGF-1) was at least 10 times more potent than insulin in stimulating the rate of ependymal 2-DG uptake, suggesting that IGF-1, rather than insulin, is the physiological agonist regulating glucose transport in ependymal cells. The predominant glucose transporter in ependymal cell cultures was found to be GLUT1, which is apparently regulated by IGF-1 in ependymal cells.

The effects of cyclooxygenase isozyme inhibition on incisional wound healing in mouse skin.

In addition to their proinflammatory activities, prostaglandins recently have been shown to be beneficial in the resolution of tissue injury and inflammation. Thus, inhibition of cyclooxygenase-2, the predominant prostaglandin endoperoxide synthase under these conditions, may not only result in attenuating the inflammatory response but also in delaying tissue regeneration and repair. To this end, we investigated cyclooxygenase isozyme expression and the effects of cyclooxygenase inhibitors on wound healing upon full-thickness incisions in mouse skin. Immunohistochemical analysis revealed prominent expression of cyclooxygenase isozymes in keratinocytes of the hyperplastic epithelium, with cyclooxygenase-1 immunosignals predominating in the suprabasal compartment and cyclooxygenase-2 immunosignals spread throughout the whole epidermis. Moreover, dendritic cells, resembling Langerhans cells, as well as endothelial cells and macrophages in the vicinity of or within the granulation tissue were found to express both isozymes. Inhibition of prostaglandin E2 synthesis by oral administration of the cyclooxygenase-1-selective inhibitor SC-560 or the cyclooxygenase-2-selective inhibitor valdecoxib did not retard wound healing in mouse skin macroscopically. Except for a slight transient retardation of epithelialization early after wounding wound-induced neoangiogenesis, collagen deposition, and the restoration of tensile strength were not delayed by these agents. Likewise, the nonselective inhibitor indomethacin had no effect on the tensile strength of incisional skin wounds.