Electrophilic compounds are a newly recognized class of redox‐active neuroprotective compounds with electron deficient, electrophilic carbon centers that react with specific cysteine residues on targeted proteins via thiol (S‐)alkylation. Although plants produce a variety of physiologically active electrophilic compounds, the detailed mechanism of action of these compounds remains unknown. Catechol ring‐containing compounds have attracted attention because they become electrophilic quinones upon oxidation, although they are not themselves electrophilic. In this study, we focused on the neuroprotective effects of one such compound, carnosic acid (CA), found in the herb rosemary obtained from Rosmarinus officinalis. We found that CA activates the Keap1/Nrf2 transcriptional pathway by binding to specific Keap1 cysteine residues, thus protecting neurons from oxidative stress and excitotoxicity. In cerebrocortical cultures, CA‐biotin accumulates in non‐neuronal cells at low concentrations and in neurons at higher concentrations. We present evidence that both the neuronal and non‐neuronal distribution of CA may contribute to its neuroprotective effect. Furthermore, CA translocates into the brain, increases the level of reduced glutathione in vivo, and protects the brain against middle cerebral artery ischemia/reperfusion, suggesting that CA may represent a new type of neuroprotective electrophilic compound.

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Jak3 is a tyrosine kinase mediating cytokine receptor signaling through the association with the common gamma chain of the cytokine receptors such as IL-2, IL-4, IL-7, IL-9, and IL-15. Unlike other members of the Jak family, the expression of Jak3 is highly restricted in hematopoietic cells. To elucidate in vivo function of Jak3, Jak3-deficient mice were generated by homologous recombination. Mice homozygous for Jak3 null mutation showed severe defects, specifically in lymphoid cells. B cell precursors in bone marrow, thymocytes, and both T and B cells in the spleen drastically decreased, although these defects were significantly recovered as aging occurred. Peripheral lymph nodes, NK cells, dendritic epidermal T cells, and intestinal intraepithelial gamma delta T cells were absent. Normal number of hematopoietic stem cells in bone marrow from Jak3-deficient mice and the similar capability to generate myeloid and erythroid colonies as wild-type mice indicated specific defects in lymphoid stem cells. Furthermore, the abnormal architecture of lymphoid organs suggested the involvement of Jak3 in the function of epithelial cells. T cells developed in the mutant mice did not respond to either IL-2, IL-4, or IL-7. These findings establish the crucial role of Jak3 in the development of lymphoid cells.

Oxidative stress has long been linked to the pathogenesis of neurodegenerative diseases; however, whether it is a cause or merely a consequence of the degenerative process is still unknown. We show that mice deficient in Cu, Zn-superoxide dismutase (SOD1) have features typical of age-related macular degeneration in humans. Investigations of senescent Sod1 ؊/؊ mice of different ages showed that the older animals had drusen, thickened Bruch's membrane, and choroidal neovascularization. The number of drusen increased with age, and exposure of young Sod1 ؊/؊ mice to excess light induced drusen. The retinal pigment epithelial cells of Sod1 ؊/؊ mice showed oxidative damage, and their ␤-cateninmediated cellular integrity was disrupted, suggesting that oxidative stress may affect the junctional proteins necessary for the barrier integrity of the retinal pigment epithelium. These observations strongly suggest that oxidative stress may play a causative role in age-related retinal degeneration, and our findings provide evidence for the free radical theory of aging. In addition, these results demonstrate that the Sod1 ؊/؊ mouse is a valuable animal model to study human age-related macular degeneration.animal model ͉ superoxide dismutase A ge-related macular degeneration (AMD) is the leading cause of legal blindness in humans in developed countries (1-5). AMD is characterized by a progressive degeneration of the macula, usually bilateral, leading to a severe decrease in vision and a central scotoma. The decrease in vision results either from retinal degeneration, called geographic atrophy (dry or nonexudative AMD), or from the secondary effects of choroidal neovascularization (CNV; wet or exudative AMD). An early sign of AMD is the appearance of drusen, which are extracellular deposits that accumulate below the retinal pigment epithelium (RPE) and are known to be risk factors for developing CNV (6-8).Mouse models of AMD that manifest some of the features of human AMD have recently begun to appear (9-14); however, most of these mice have only some of the characteristics of human AMD (15). The severity of AMD in humans progresses with increasing age, finally resulting in extensive degeneration of the retina. Therefore, animal models that mimic the complex and progressive characteristics of AMD are needed to investigate the pathogenesis of AMD.Oxidative stress, which refers to cellular or molecular damage caused by reactive oxygen species (ROS), has been implicated in many age-related diseases and aging itself (16,17). ROS include free radicals, hydrogen peroxide, and singlet oxygen and are often the by-products of oxygen metabolism. The retina is particularly susceptible to oxidative stress because of its high consumption of oxygen, high concentration of polyunsaturated fatty acids, and exposure to light (18). A growing body of evidence suggests that cumulative oxidative damage may be responsible for AMD (18, 19); however, a causative link has not been definitively demonstrated (18).To determine whether there is a causative ro...

The apical and basolateral plasma membrane domains of polarized epithelial cells contain distinct sets of integral membrane proteins. Biosynthetic targeting of proteins to the basolateral plasma membrane is mediated by cytosolic tail determinants, many of which resemble signals involved in the rapid endocytosis or lysosomal targeting. Since these signals are recognized by adaptor proteins, we hypothesized that there could be epithelial-specific adaptors involved in polarized sorting. Here, we report the identification of a novel member of the adaptor medium chain family, named W W1B, which is closely related to the previously described W W1A (79% amino acid sequence identity). Northern blotting and in situ hybridization analyses reveal the specific expression of W W1B mRNA in a subset of polarized epithelial and exocrine cells. Yeast two-hybrid analyses show that W W1B is capable of interacting with generic tyrosine-based sorting signals. These observations suggest that W W1B may be involved in protein sorting events specific to polarized cells.