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A survey method was applied to a sample of 145 self-identified African American members of four predominantly African American churches to assess the influence of Tyler Perry’s House of Payne and Meet the Browns television shows on their racial identity and how they perceived and evaluated the shows. Results indicate that (1) particular socioeconomic factors, more specifically education attainment, may negatively influence exposure to House of Payne and Meet the Browns, 2) religiosity may account for viewers’ exposure more to House of Payne than to Meet the Browns, 3) House of Payne may have a more significant influence on viewers” black identity than Meet the Browns, 4) Frequency of exposure, income, and education may predict affective evaluation and perceived accuracy of both House of Payne and Meet the Browns, and 5) House of Payne may be considered a more accurate and positive reflection of the black group experience than Meet the Browns.

IL-15 induces proliferation, inhibits apoptosis and increases IL-4 production in murine mast cells. There is evidence that these activities are mediated via the uncharacterised receptor, IL-15R-X, rather than the classical three-chain IL-15 receptor. Effects of IL-15 on important aspects of mast cell biology, such as migration and degranulation, are unknown. We report that IL-15 induces migration of murine and human mast cells in a dose-dependent and biphasic manner, with peaks of migration occurring at approximately 10(-15) and approximately 10(-9) M. The potency of the response was similar to that induced by other well-established mast cell chemoattractants. Competition assays performed with murine and human mast cells indicate that both peaks of migration are due to chemotaxis. Pre-treatment of cells with pertussis toxin (PTX), a guanine nucleotide-binding regulatory protein (G-protein) inhibitor, resulted in complete inhibition of murine mast cell migration at approximately 10(-15) M IL-15, and human mast cell migration at approximately 10(-15) and approximately 10(-9) M. This demonstrates that murine and human mast cells express a PTX-sensitive receptor, activated in response to IL-15. Additionally, IL-15 did not induce degranulation in murine mast cells. Locally-produced IL-15 may contribute to mast cell recruitment during inflammatory responses, thereby acting as a linking cytokine between innate and adaptive arms of the immune system.

Tryptases are serine proteases that are thought to be uniquely and proteolytically active as tetramers. Crystallographic studies reveal that the active tetramer is a flat ring structure composed of four monomers, with their active sites arranged around a narrow central pore. This model explains why many of the preferred substrates of tryptase are short peptides; however, it does not explain how tryptase cleaves large protein substrates such as fibronectin, although a number of studies have reported in vitro mechanisms for generating active monomers that could digest larger substrates. Here we suggest that alternate mRNA splicing of human tryptase genes generates active tryptase monomers (or dimers). We have identified a conserved pattern of alternate splicing in four tryptase alleles (αII, βI, βIII, and δI), representing three distinct tryptase gene loci. When compared with their full-length counterparts, the splice variants use an alternate acceptor site within exon 4. This results in the deletion of 27 nucleotides within the central coding sequence and 9 amino acids from the translated protein product. Although modeling suggests that the deletion can be easily accommodated by the enzymes structurally, it is predicted to alter the specificity by enlarging the S1′ or S2′ binding pocket and results in the complete loss of the “47 loop,” reported to be critical for the formation of tetramers. Although active monomers can be generated in vitro using a range of artificial conditions, we suggest that alternate splicing is the in vivo mechanism used to generate active tryptase that can cleave large protein substrates.