Ligand-dependent activation of the melanocortin 5 receptor: cAMP production and ryanodine receptor-dependent elevations of [Ca(2+)](I).

The melanocortins are involved in the regulation of various cognitive and physiological processes such as learning, feeding, immune suppression, pigmentation, and sebum production. Five melanocortin receptors have been identified, of which the melanocortin 5 receptor (MC5R) has the most widespread distribution. This subtype is found in the brain, and at numerous peripheral sites including the skin where it is expressed in the sebaceous glands. The purpose of this study was to identify the peptide that functions as a natural ligand at the MC5R in the skin. alpha-MSH, ACTH1-39, ACTH1-17, ACTH1-10, and ACTH4-10 all increased the production of cAMP in HEK293 cells transfected with the mouse MC5R. alpha-MSH and ACTH1-17 were the most potent in this respect. In addition, all peptides stimulated a rapid and transient increase in [Ca(2+)](i), and, ACTH1-10 was the most potent. The increases in [Ca(2+)](i) were of intracellular origin, but not associated with inositol phosphate production. The elevations in [Ca(2+)](i) were reduced by ruthenium red and procaine and it is therefore possible that they were mediated via ryanodine receptors.     

Different activities of the adenovirus types 5 and 12 E1A regions in transformation with the EJ Ha-ras oncogene.

We have compared the capacities of the E1A regions of nononcogenic adenovirus type 5 (Ad5) and highly oncogenic Ad12 to cooperate with the EJ bladder carcinoma Ha-ras-1 oncogene in the transformation of primary baby rat kidney cells. Both E1A regions, when cotransfected with the Ha-ras oncogene, transformed the primary cells with a low frequency. Ad5 E1A plus Ha-ras-transformed cells differed in phenotype from cells transformed by Ad12 E1A plus Ha-ras. The cells expressing Ad5 E1A appeared highly transformed and practically failed to adhere to plastic. This phenotype may be due to the virtually complete absence of fibronectin gene expression in these cells. In contrast, the cells expressing Ad12 E1A were flatter and adhered to plastic, whereas fibronectin gene expression was reduced but not absent. The oncogenic potential of the two types of E1A plus ras-transformed cells was tested by their injection into both athymic nude mice and weanling syngeneic rats. The Ad5 E1A plus ras-transformed cells were found to be highly oncogenic in both animal species, whereas the Ad12 E1A plus ras-transformed cells were only weakly oncogenic in both syngeneic rats and nude mice. The difference in oncogenic potential of the Ad5 E1A plus ras- and the Ad12 E1A plus ras-transformed cells is discussed in terms of the different capacities of the Ad5 and Ad12 E1A-encoded proteins to modulate cellular gene expression.     

The capsular polysaccharide of Haemophilus influenzae type B prevents killing by complement and antibodies against outer membrane protein a

Abstract The ability of antibodies, raised in rabbits against purified outer membrane protein a ( M _r 47 000) of Haemophilus influenzae type b, to promote complement-dependent killing of these encapsulated organisms was investigated. Killing of encapsulated strains was not induced by these antibodies in conjunction with either human, mouse, rabbit or guinea-pig complement. Acapsular mutants were effectively killed by complement in the presence of antibodies against protein a . Killing was dependent on the presence of the 47-kDa protein a and was not influenced by the outer membrane protein subtype or lipopolysaccharide serotype of the strain. The killing-promoting activity could be absorbed from the sera with cells of strains with the same protein a , purified protein a , but not by purified lipopolysaccharide and capsular polysaccharide. Binding experiments showed that the encapsulated strain and its acapsular mutant bound antibodies against protein a with the same rate and to the same extent, indicating that the capsule probably interferes with complement activation or insertion of the membrane attack complex into the bacterial cell.     

IL-17 promotes bone erosion in murine collagen-induced arthritis through loss of the receptor activator of NF-kappa B ligand/osteoprotegerin balance

IL-17 is a T cell-derived proinflammatory cytokine in experimental arthritis and is a stimulator of osteoclastogenesis in vitro. In this study, we report the effects of IL-17 overexpression (AdIL-17) in the knee joint of type II collagen-immunized mice on bone erosion and synovial receptor activator of NF-kappa B ligand (RANKL)/receptor activator of NF-kappa B/osteoprotegerin (OPG) expression. Local IL-17 promoted osteoclastic bone destruction, which was accompanied with marked tartrate-resistant acid phosphatase activity at sites of bone erosion in cortical, subchondral, and trabecular bone. Accelerated expression of RANKL and its receptor, receptor activator of NF-kappa B, was found in the synovial infiltrate and at sites of focal bone erosion, using specific immunohistochemistry. Interestingly, AdIL-17 not only enhanced RANKL expression but also strongly up-regulated the RANKL/OPG ratio in the synovium. Comparison of arthritic mice from the AdIL-17 collagen-induced arthritis group with full-blown collagen-arthritic mice having similar clinical scores for joint inflammation revealed lower RANKL/OPG ratio and tartrate-resistant acid phosphatase activity in the latter group. Interestingly, systemic OPG treatment prevented joint damage induced by local AdIL-17 gene transfer in type II collagen-immunized mice. These findings suggest T cell IL-17 to be an important inducer of RANKL expression leading to loss of the RANKL/OPG balance, stimulating osteoclastogenesis and bone erosion in arthritis.     

IL-1 receptor type 1 gene-deficient mice demonstrate an impaired host defense against pneumococcal meningitis

The fatality rate associated with Streptococcus pneumoniae meningitis remains high despite adequate antibiotic treatment. IL-1 is an important proinflammatory cytokine, which is up-regulated in brain tissue after the induction of meningitis. To determine the role of IL-1 in pneumococcal meningitis we induced meningitis by intranasal inoculation with 8 x 10(4) CFU of S. pneumoniae and 180 U of hyaluronidase in IL-1R type I gene-deficient (IL-1R(-/-)) mice and wild-type mice. Meningitis resulted in elevated IL-1alpha and IL-1beta mRNA and protein levels in the brain. The absence of an intact IL-1 signal was associated with a higher susceptibility to develop meningitis. Furthermore, the lack of IL-1 impaired bacterial clearance, as reflected by an increased number of CFU in cerebrospinal fluid of IL-1R(-/-) mice. The characteristic pleocytosis of meningitis was not significantly altered in IL-1R(-/-) mice, but meningitis was associated with lower brain levels of cytokines. The mortality was significantly higher and earlier in the course of the disease in IL-1R(-/-) mice. These results demonstrate that endogenous IL-1 is required for an adequate host defense in pneumococcal meningitis.     

Subpicosecond resonance Raman spectra of the early intermediates in the photocycle of bacteriorhodopsin

The resonance Raman spectra are presented for the species formed during the photocycle of bacteriorhodopsin (bR) on a timescale of 800-900 fs. In the ethylenic stretch region two intermediates were found with frequencies of 1,510 and 1,518 cm^-1, corresponding to species with optical absorption maxima at 660 and 625 nm, respectively. This leads to the assignment of the 1,518 cm^-1 band to the J₆₂₅ intermediate. In the fingerprint region, the appearance of a vibration at 1,195 cm^-1 strongly suggests that the isomerization indeed has taken place in a time less than the pulsewidth of our laser. This supports the previous proposals made on the basis of the optical spectra. The spectra are compared with those observed in tens of picoseconds up to nanoseconds.