SummaryStructural genes of phospholipid biosynthesis in the yeast Saccharomyces cerevisiae are transcriptionally co-regulated by ICRE (inositol/choline-responsive element) promoter motifs. Gene activation by an ICRE is mediated by binding of the Ino2/Ino4 transcription factor, whereas repression in the presence of high concentrations of inositol and choline (IC) requires an intact Opi1 repressor. However, the mechanism of specific repression and the functional interplay among these regulators remained unclear from previous work. Using in vivo as well as in vitro interaction assays, we show binding of the pleiotropic repressor Sin3 to the pathwayspecific regulator Opi1. The paired amphipathic helix 1 (PAH1) within Sin3 and OSID (Opi1 -Sin3 interaction domain) in the N-terminus of Opi1 were mapped as contact sites. The regulatory significance of the Opi1 -Sin3 interaction was shown by the obvious deregulation of an ICRE-dependent reporter gene in a sin3 mutant. Opi1 also interacts with a newly identified functional domain of the transcriptional activator Ino2 (RID, repressor interaction domain). These results define the molecular composition of the transcription complex mediating control of ICREdependent genes and allow a hypothesis on the flow of regulatory information in response to phospholipid precursors.

The N-methyl-D-aspartate receptor (NMDAR) is a Na(+) and Ca(2+) permeable ionotropic glutamate receptor that is activated by the coagonists glycine and glutamate. NMDARs are critical to synaptic signaling and plasticity, and their dysfunction has been implicated in a number of neurological disorders, including schizophrenia, depression, and Alzheimer's disease. Herein we describe the discovery of potent GluN2A-selective NMDAR positive allosteric modulators (PAMs) starting from a high-throughput screening hit. Using structure-based design, we sought to increase potency at the GluN2A subtype, while improving selectivity against related α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs). The structure-activity relationship of channel deactivation kinetics was studied using a combination of electrophysiology and protein crystallography. Effective incorporation of these strategies resulted in the discovery of GNE-0723 (46), a highly potent and brain penetrant GluN2A-selective NMDAR PAM suitable for in vivo characterization.

SummaryIn the yeast Saccharomyces cerevisiae , genes involved in phospholipid biosynthesis are activated by ICRE (inositol/choline-responsive element) upstream motifs and the corresponding heterodimeric binding factor, Ino2 + + + + Ino4. Both Ino2 and Ino4 contain basic helix-loop-helix (bHLH) domains required for ICRE binding, whereas transcriptional activation is mediated exclusively by Ino2. In this work, we describe a molecular analysis of functional minimal domains responsible for specific DNA recognition and transcriptional activation (TAD1 and TAD2). We also define the importance of individual amino acids within the more important activation domain TAD1. Random mutagenesis at five amino acid positions showed the importance of acidic as well as hydrophobic residues within this minimal TAD. We also investigated the contribution of known general transcription factors and co-activators for Ino2-dependent gene activation. Although an ada5 single mutant and a gal11 paf1 double mutant were severely affected, a partial reduction in activation was found for gcn5 and srb2 . Ino2 interacts physically with the basal transcription factor Sua7 (TFIIB of yeast). Interestingly, interaction is mediated by the HLH dimerization domain of Ino2 and by two non-overlapping domains within Sua7. Thus, Sua7 may compete with Ino4 for binding to the Ino2 activator, creating the possibility of positive and negative influence of Sua7 on ICREdependent gene expression.

The basic defect in lepromatous leprosy is the selective unresponsiveness of T cells to the antigens of Mycobacterium leprae (1). This defect may be partial or complete (2) and does not appear to change with prolonged chemotherapy (3). A lack of T cell-derived lymphokines such as IFN-y and IL-2 could account for the inability of macrophages and other cells to eliminate M. leprae .Attempts to circumvent T cell unresponsiveness have already been initiated in both in vitro systems (2, 4-6) and in the confines of the cutaneous lesions. Initial observations have been reported on the efficacy of crossreacting antigens such as purified protein derivative of tuberculin (PPD)' and the lymphokine rIFN-. y (7-10) . In the case of PPD, intradermal administration has led to a long-lived emigratory mononuclear leukocyte response, the local destruction of parasitized macrophages, and a striking reduction in the number of M. leprae within 21 d. These responses and the accompanying modification of cellular subsets are evidence of a vigorous cell-mediated immune reaction in the environment ofa lepromatous lesion . Similar observations have been made after IFN-y administration (manuscript in preparation).We have now extended these observations to the use of human rIL-2. This lymphokine serves as an autocrine T cell growth factor, and induces the formation of lymphokines with other functions (11,12). We report results on the use of small doses of IL-2, in the skin of lepromatous patients, and the reconstitution of cutaneous cellular immunity. Volume 169 March 1989 893-907 Materials and Methods Patient Population . 35 patients, 18-60 yr old, 23 with lepromatous leprosy (LL) and 12 with borderline lepromatous leprosy (BL) (13), were selected for the intradermal administra-

No abstract