Samuel H. Barondes, MD - US grants

We propose to continue studies of the role of lectins in development of embryonic chick tissues and slime mold cells. In the past year we have extended to three the number of developmentally regulated chicken lectins that we have purified. Two arelactose-binding lectins and are called chicken-lactose-lectin-I and chicken-lactose-lectin-II; and the third which binds geparin and N-acetyl-galactosamine is called chicken-heparin-lectin. We propose to determine the quantity of these lectins in different tissues and at different stages of chick development using a radioimmunoassay; and to localize the lectins with chick tissues by immunohistochemistry. Our work with slime molds is concentrated on purpurin, the lectin from Dictyosteium purpurem, which we have recently found to exist in seven distinct forms which we have now separated. We propose to determine the developmental regulation and distribution of these forms. Efforts to identify and localize endogenous receptors for slime mold lectins continue.

Soluble extracts of many mammalian tissues, including lung and spleen, contain Beta-galactoside binding lectins. Three were recently purified from rat lung with subunit Mrs 14,500, 18,000 and 29,000 (RL-14.5, RL-18 and Rl-29) and two were purified from human lung (HL-14 and HL-29). Previous work suggests that these lectins function at the cell surface or extracellularly by interacting with specific glycoconjugates. Our goal is to accumulate structural and functional information about these lectins which will lead to an understanding of their biological roles. THe biological studies will be done with lymphocytes because they have many practical advantages and contain both RL-14.5 and receptors for this lectin. These studies will contribute to a general understanding of endogenous lectin functions in the many tissues which contain them. We propose to: a. Identify relative binding of these endogenous lectins to a large panel of known mammalian glycoconjugates, to define their active sites and potential competitive interactions. b. Identify lymphocyte glycoproteins and glycolipids which act as receptors for these endogenous lectins, as judged by their binding properties. c. Examine the biological effects of these lectins. Initially we will continue our studies which show that exogenous RL-14.5 activates B or T lymphocytes (but only in conjunction with specific growth factors). Then we will determine if this endogenous lectin (which we find in virtually all B and most T lymphocytes) is secreted and involved in the lymphocyte activation which normally results from specific cell-cell interactions. d. Clone the genes for HL-14, HL-29 and related mammalian lectins. The genes will be used to deduce amino acid sequences; to determine if there are multiple forms of the lectins under different developmental control; and for functional studies using lymphocyte cell lines transformed with anti-sense DNA.

health science research support; university;

gas chromatography; mass spectrometry; biomedical equipment resource;

biomedical equipment purchase; high performance liquid chromatography;

A soluble beta-galactoside-binding lectin with subunit molecular weight of about 14,000 has been isolated from many vertebrate tissues. The lectin shows striking developmental regulation in certain tissues and has been detected on the surface of cells and in the extracellular matrix surounding them, suggesting possible roles in regulation of cellular development and in morphogenesis. Recent studies with the human form of this lectin indicate that there are several variants which are the products of distinct genes. These findings raise the possibility that these, like other lectins, may have a second functional domain distinct from their carbohydrate binding sites. They also raise the possibility that these structural variations mediate specificity in glycoconjugate binding. The purpose of this project is to further characterize this gene family in humans, with the ultimate aim of understanding its regulation and functions. To this end, a series of full length human cDNAs will be isolated and sequenced. The human genomic DNAs encoding members of this gene family will also be isolated and sequenced.

biomedical equipment resource; biomedical equipment purchase;

Bipolar disorder is a common mental illness characterized by one or more periods of mania and depression. Family and adoption studies support the existence of genetic factors in the expression of the disorder in a significant percentage of affected individuals. The ultimate goal of this proposal is to identify a gene or genes that predispose to the development of bipolar disorder. The studies proposed will examine 2 extended pedigrees, one Amish and the other Costa Rican. In the Amish pedigree individuals with bipolar disorder have been clearly identified, and lymphoblast cell lines are available for genetic analysis. Since recent work has put earlier linkage findings into question, we propose to screen the genome for linkage. To minimize problems that might arise from the existence of more than one gene predisposing to BP even in this limited population we will confine our attention to kinships with one affected ancestor. A distinctive feature of our approach is to study only clearly affected members, and to do this intensively using novel somatic cell genetic and molecular techniques to substantially increase the amount of information that we gain from each individual. This will be done by examining individual chromosomes from each affected individual in somatic cell hybrids, and by developing techniques to make studies with all markers informative by detecting polymorphisms specifically present within this particular pedigree. The Costa Rican pedigree has a high prevalence of bipolar disorder and contains over 500 living members. Preliminary studies indicate that 30 of 130 individuals satisfy diagnostic criteria for major affective disorder in a manner consistent with autosomal dominant transmission. We propose a detailed diagnostic assessment of this population, establishment of cell lines from all members, and linkage studies using both the conventional RFLP approach and, when necessary, the novel techniques that we are developing in work with the Amish material.

biomedical equipment purchase;