Proceedings of the National Academy of Sciences of the United States of America
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Proc. Natl. Acad. Sci. U.S.A. · Nov 2001
CD5 expression by B lymphocytes and its regulation upon Epstein-Barr virus transformation.
Dim expression of CD5 on human B lymphocytes has been used to delineate B1 and B2 subsets. Nevertheless, others have suggested that the molecule is an activation marker and does not predicate a subset distinction. We have used enzymatic amplification staining, a technology that enhances the resolution of flow cytometric analysis of cell surface molecules by as much as 100-fold, to determine that essentially all human B cells express CD5. Furthermore, we show that this expression is regulated during Epstein-Barr virus transformation.
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Proc. Natl. Acad. Sci. U.S.A. · Nov 2001
Cholinergic dilation of cerebral blood vessels is abolished in M(5) muscarinic acetylcholine receptor knockout mice.
The M(5) muscarinic receptor is the most recent member of the muscarinic acetylcholine receptor family (M(1)-M(5)) to be cloned. At present, the physiological relevance of this receptor subtype remains unknown, primarily because of its low expression levels and the lack of M(5) receptor-selective ligands. To circumvent these difficulties, we used gene targeting technology to generate M(5) receptor-deficient mice (M5R(-/-) mice). ⋯ This effect was specific for cerebral blood vessels, because acetylcholine-mediated dilation of extra-cerebral arteries remained fully intact in M5R(-/-) mice. Our findings provide direct evidence that M(5) muscarinic receptors are physiologically relevant. Because it has been suggested that impaired cholinergic dilation of cerebral blood vessels may play a role in the pathophysiology of Alzheimer's disease and focal cerebral ischemia, cerebrovascular M(5) receptors may represent an attractive therapeutic target.
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Differential expression of ion channels contributes functional diversity to sensory neuron signaling. We find nerve injury induced by the Chung model of neuropathic pain leads to striking reductions in voltage-gated K(+) (Kv) channel subunit expression in dorsal root ganglia (DRG) neurons, suggesting a potential molecular mechanism for hyperexcitability of injured nerves. ⋯ These neurons are presumably nociceptors, because they also express the VR-1 capsaicin receptor, calcitonin gene-related peptide, and/or Na(+) channel SNS/PN3/Nav1.8. In contrast, larger diameter neurons associated with mechanoreception and proprioception express high levels of Kv1.1 and Kv1.2 without Kv1.4 or other Kv1 alpha subunits, suggesting that heteromers of these subunits predominate on large, myelinated afferent axons that extend from these cells.
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Proc. Natl. Acad. Sci. U.S.A. · Oct 2001
Poly(ADP-ribose) glycohydrolase mediates oxidative and excitotoxic neuronal death.
Excessive activation of poly(ADP-ribose) polymerase 1 (PARP1) leads to NAD(+) depletion and cell death during ischemia and other conditions that generate extensive DNA damage. When activated by DNA strand breaks, PARP1 uses NAD(+) as substrate to form ADP-ribose polymers on specific acceptor proteins. These polymers are in turn rapidly degraded by poly(ADP-ribose) glycohydrolase (PARG), a ubiquitously expressed exo- and endoglycohydrolase. ⋯ Immunostaining for poly(ADP-ribose) on Western blots and neuron cultures showed benzamide to decrease and gallotannin to increase poly(ADP-ribose) accumulation during MNNG exposure. These results suggest that PARG inhibitors do not inhibit PARP1 directly, but instead prevent PARP1-mediated cell death by slowing the turnover of poly(ADP-ribose) and thus slowing NAD(+) consumption. PARG appears to be a necessary component of the PARP-mediated cell death pathway, and PARG inhibitors may have promise as neuroprotective agents.
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Proc. Natl. Acad. Sci. U.S.A. · Sep 2001
Targeted adenovirus-induced expression of IL-10 decreases thymic apoptosis and improves survival in murine sepsis.
Sepsis remains a significant clinical conundrum, and recent clinical trials with anticytokine therapies have produced disappointing results. Animal studies have suggested that increased lymphocyte apoptosis may contribute to sepsis-induced mortality. ⋯ Improvements in survival were associated with increases in Bcl-2 expression and reductions in caspase-3 activity and thymocyte apoptosis. These studies demonstrate that thymic apoptosis plays a critical role in the pathogenesis of sepsis and identifies a gene therapy approach for its therapeutic intervention.