Investigation into the structure-activity relationship of novel concentration dependent, dual action T-type calcium channel agonists/antagonists

This paper describes the synthesis and biological evaluation of a series of straight chain analogs of a compound (1) that was previously synthesized in our research program. These compounds, which are T-type calcium channel antagonists, exhibits potent anti-proliferative activity against a variety of cancer cells. A structure-activity relationship of these analogs against a variety of cancer cells has provided insight into a logical pharmacophore for this series of compounds. Furthermore, this series of compounds has presented itself as a set of novel, concentration dependent, dual action agonists/antagonists for the T-type calcium channel.     

Viral induction of inflammatory cytokines in human epithelial cells follows a p38 mitogen-activated protein kinase-dependent but NF-kappa B-independent pathway

The initial step in an immune response toward a viral infection is the induction of inflammatory cytokines. This innate immune response is mediated by expression of a variety of cytokines exemplified by TNF-alpha and IL-1beta. A key signal for the recognition of intracellular viral infections is the presence of dsRNA. Viral infections and dsRNA treatment can activate several signaling pathways including the protein kinase R pathway, mitogen-activated protein kinase (MAPK) pathways, and NF-kappaB, which are important in the expression of inflammatory cytokines. We previously reported that activation of protein kinase R was required for dsRNA induction of TNF-alpha, but not for IL-1beta. In this study, we report that activation of the p38 MAPK pathway by respiratory viral infections is necessary for induction of inflammatory cytokines in human bronchial epithelial cells. Inhibition of p38 MAPK by two different pharmacological inhibitors showed that expression of both TNF-alpha and IL-1beta required activation of this signaling pathway. Interestingly, inhibition of NF-kappaB did not significantly reduce viral induction of either cytokine. Our data show that, during the initial infections of epithelial cells with respiratory viruses, activation of the p38 MAPK pathway is associated with induction of inflammation, and NF-kappaB activation may be less important than previously suggested.     

The mouse model of amebic colitis reveals mouse strain susceptibility to infection and exacerbation of disease by CD4+ T cells

Amebic colitis is an important worldwide parasitic disease for which there is not a well-established animal model. In this work we show that intracecal inoculation of Entamoeba histolytica trophozoites led to established infection in 60% of C3H mice, while C57BL/6 or BALB/c mice were resistant, including mice genetically deficient for IL-12, IFN-gamma, or inducible NO synthase. Infection was a chronic and nonhealing cecitis that pathologically mirrored human disease. Characterization of the inflammation by gene chip analysis revealed abundant mast cell activity. Parasite-specific Ab and cellular proliferative responses were robust and marked by IL-4 and IL-13 production. Depletion of CD4(+) cells significantly diminished both parasite burden and inflammation and correlated with decreased IL-4 and IL-13 production and loss of mast cell infiltration. This model reveals important immune factors that influence susceptibility to infection and demonstrates for the first time the pathologic contribution of the host immune response in amebiasis.     

Mesopone cytochrome c peroxidase: functional model of heme oxygenated oxidases

The effect of heme ring oxygenation on enzyme structure and function has been examined in a reconstituted cytochrome c peroxidase. Oxochlorin derivatives were formed by OsO(4) treatment of mesoporphyrin followed by acid-catalyzed pinacol rearrangement. The northern oxochlorin isomers were isolated by chromatography, and the regio-isomers assignments determined by 2D COSY and NOE 1H NMR. The major isomer, 4-mesoporphyrinone (Mp), was metallated with FeCl(2) and reconstituted into cytochrome c peroxidase (CcP) forming a hybrid green protein, MpCcP. The heme-altered enzyme has 99% wild-type peroxidase activity with cytochrome c. EPR spectroscopy of MpCcP intermediate compound I verifies the formation of the Trp(191) radical similar to wild-type CcP in the reaction cycle. Peroxidase activity with small molecules is varied: guaiacol turnover increases approximately five-fold while that with ferrocyanide is approximately 85% of native. The electron-withdrawing oxo-substitutents on the cofactor cause a approximately 60-mV increase in Fe(III)/Fe(II) reduction potential. The present investigation represents the first structural characterization of an oxochlorin protein with X-ray intensity data collected to 1.70 A. Although a mixture of R- and S-mesopone isomers of the FeMP cofactor was used during heme incorporation into the apo-protein, only the S-isomer is found in the crystallized protein.     

The kinesin-associated protein UNC-76 is required for axonal transport in the Drosophila nervous system

Kinesin-I is essential for the transport of membrane-bound organelles in neural and nonneural cells. However, the means by which kinesin interacts with its intracellular cargoes, and the means by which kinesin-cargo interactions are regulated in response to cellular transport requirements are not fully understood. The C terminus of the Drosophila kinesin heavy chain (KHC) was used in a two-hybrid screen of a Drosophila cDNA library to identify proteins that bind specifically to the kinesin tail domain. UNC-76 is an evolutionarily conserved cytosolic protein that binds to the tail domain of KHC in two-hybrid and copurification assays, indicating that kinesin and UNC-76 form a stable complex in vivo. Loss of Drosophila Unc-76 function results in locomotion and axonal transport defects reminiscent of the phenotypes observed in kinesin mutants, suggesting that UNC-76 is required for kinesin-dependent axonal transport. Unc-76 exhibits dosage-sensitive genetic relationships with Khc and Kinesin light chain mutations, further supporting the hypothesis that UNC-76 and kinesin-I work in a common transport pathway. Given the interaction of FEZ1, the mammalian homolog of UNC-76, with protein kinase Czeta, and the role of FEZ1 in axon outgrowth, we propose that UNC-76 helps integrate kinesin activity in response to transport requirements in axons.