Tentativeness and fervor in cell biology require negative and positive feedforward control

Systematic discovery of the grammar of translational inhibition by RNA hairpins

Recent discovery of gene expression mechanisms has propelled molecular genetics to a state of rapid development, a state likely to persist due to continuing advances in understanding control systems of fundamental cellular processes. An algorithm for that advancement starts in this paper with a gene of interest and a characteristic function of that gene. The set of all genes with counteracting function is identified by pathway searches. Also associated with the first gene is the set of the genes which byproducts of its transcription might downregulate, identified relative to searches involving sequence alignments. Our focus is the intersection of the counteracting gene set and the downregulated gene set. The result is hypothesis generation. Examples of and predictions from this approach are given in the context of apoptosis. Also discussed is application of the algorithm to rational drug design from a new development platform.

Fc-signalling in the modulation of immune responses by passive antibody

Passive antibody can both suppress and augment immune responses. Until recently, there was virtual unanimity on the importance of the interaction of the Fc portion of modulating antibody with Fc-receptors (Fc-signalling), especially in experiments involving the suppression by antibody. Experiments reported in the last few years, that do not demonstrate the range of Fc-portion/Fc-receptor influences on the suppression of immune responses by passive antibody, have introduced new uncertainty into this field. The purpose of this paper is to review how the initial controversy on the influence of Fc-signalling in inhibition by passive antibody was resolved. Old and new approaches are suggested that may help in resolving the current uncertainty engendered by recent experimental results that were interpreted to mean that passive suppressive antibody does not utilize the inhibitory FcgammaRIIB receptor. An understanding of the factors that influence negative Fc-signalling is needed in order to optimize clinical therapies whose action depends on the suppressive property of antibody.

Lipopolysaccharide-induced IgM production is not suppressed by antigen receptor ligation in B cells from some autoimmune strains of mice

Ligation of surface immunoglobulin on resting or activated nonautoimmune B cells inhibited lipopolysaccharide (LPS)-induced total IgM production. B cells from NZB, (NZB x NZW)F1, and BXSB mice were relatively resistant, but B cells from NZW or MRL/lpr mice were inhibited. The resistance occurs in B cells from young and old NZB mice, and in both resting and activated splenic NZB B cells. Anti-ssDNA responses induced by lipopolysaccharide occur in the presence of antigen-receptor-ligating antibody in NZB, but not in DBA/2, B cells. Antagonism in signaling between the antigen and LPS receptor is not a general B cell hyporesponsiveness, but defects in antagonism specifically between antigen and LPS signaling may be a predisposing factor to autoimmune disease in some autoimmune strains of mice.