Quantitation of cis versus trans regulation of mouse beta-glucuronidase. Action of alleles of the Gus-r locus determining androgen inducibility.

Genetic studies have shown that the induction of beta-glucuronidase in mouse kidney in response to androgens is under the control of the Gus-r gene, closely linked to the beta-glucuronidase structural gene, Gus-s, on mouse Chromosome 5. Despite the fact that a single structural gene codes for beta-glucuronidase, enzyme molecules show considerable charge heterogeneity, presumably as a result of post-translational events. Because the enzyme is a tetramer, this heterogeneity has complicated examination of the cis versus trans action of the Gus-r gene.

Action of granulocyte-macrophage colony-stimulating factors: studies using a human leukemia cell line.

Granulocyte-macrophage colony-stimulating factors (CSFs) have previously been shown to stimulate colony formation in soft agar culture by a human myelogenous leukemia cell line known as KG-1. We have used KG-1 cells as a model system to investigate the interaction of CSF with myeloid cells. We now report that exposure of KG-1 cells to human CSFs in liquid culture results in a rapid (within 3 hr) burst of RNA synthesis and, after a lag of about 10 hr, a stimulation of DNA and protein synthesis.

An undifferentiated variant derived from the human acute myelogenous leukemia cell line (KG-1).

A variant subline (KG-1a) of the human acute myelogenous leukemia (AML) cell line (KG-1) has been isolated. The cells retain the same constitutive markers as the parent line, including HLA antigens, isoenzymes, and karyotype. The cells from the subline are morphologically and histochemically undifferentiated blast cells, while the parent cells and several of its clones are at the myeloblast and promyelocyte stages of development.

Cytotoxicity of anti-beta 2-microglobulin xenoantisera to human and murine myeloid progenitor cells and lack of cross-reactivity with colony-stimulating activity.

A previous report has suggested an antigenic relationship between beta 2-microglobulin (beta 2 mu) and granulocyte colony-stimulating activity (CSA). Since human myeloid progenitor cells (CFU-C) express HLA antigens and beta 2 mu is a known molecular component of HLA antigens, we wondered whether the reported effect of anti-beta 2 mu heteroantisera on in vitro granulopoiesis might result from cytotoxicity to CFU-C rather than from cross-reactivity with CSA. To test this, we used rabbit antibody reactive with human and murine beta 2 mu (anti-beta 2 mu).

Growth factors.

Humoral regulation of somatic and hematopoietic cell growth has been intensely investigated during the past decade. Growth hormone is unique because it regulates the size of the person within the constraints of the genetic program. The somatomedins and insulin growth factors are low molecular weight polypeptides believed to mediate some functions of growth hormone.

Multiple structural genes for mouse amylase.

Salivary and pancreatic amylases from the mouse show both structural and quantitative genetic variation encoded within a gene complex on chromosome 3. Two fundamental questions prompted by this variation are whether salivary and pancreatic amylases are derived from different structural genes and whether multiple structural genes are causing the quantitative variation observed in each of the two amylases. These questions were approached by comparing the amylase protein from 12 congenic lines carrying amylase gene complexes derived from different origins.

Production of erythroid-potentiating activity by a human T-lymphoblast cell line.

We derived a human T-lymphoblast cell line (Mo) that constitutively elaborates certain lymphokines. The Mo cells produce a colony-stimulating factor necessary for the growth of human granulocyte-monocyte precursors in vitro as well as an erythroid-potentiating activity (EPA) that enhances the proliferation of human erythroid progenitors in vitro. In the presence of serum, the EPA in Mo-conditioned medium stimulated the growth of small and large erythroid colonies almost 2-fold.

Erythroid-potentiating activity: characterization and target cells.

We established a human T-lymphoblast cell line (Mo) that produces factors stimulating the proliferation of hematopoietic cells. These include a colony-stimulating factor for normal human granulocytes and macrophages, and a factor with erythroid-potentiating activity (EPA) that enhances the proliferation of normal human erythroid progenitors in vitro. Erythroid-potentiating activity has been partially purified and characterized.

Relationship between genetic variation in thermal stability and electrophoretic mobility of mouse beta-galactosidase.

We have examined the relationships between the genetic determinants for mouse beta-galactosidase heat stability and electrophoretic mobility, in order to clarify previous reports indicating that a variation for enzyme heat stability is restricted to kidney while that for electrophoretic mobility is expressed in all tissues. We find that the two phenotypes show concordant strain distributions and cosegregate in genetic crosses. In contrast to a previous report, the thermal stability variation is expressed in all tissues, although the absolute rate of enzyme inactivation is tissue specific.

X-linked and autosomal genes controlling mouse alpha-galactosidase expression.

Analysis of F2 and backcross animals has confirmed the X-chromosome linkage of Ags, the structural locus for mouse alpha-galactosidase. The position of Ags has been located in the X chromosome, 9 centimorgans from Mo, and the gene order is centromere-Hq-Bn-Ta-Mo-Ags. A variation in the developmental expression of alpha-galactosidase activity, inherited as an autosomal trait, has been characterized using recombinant inbred lines of mice.

Relationships between levels of membrane-bound glucuronidase and the associated protein egasyn in mouse tissues.

Mouse beta-glucuronidase has a dual intracellular localization, being present in both endoplasmic reticulum and lysosomes of several tissues. Previous studies demonstrated that the protein egasyn is complexed with microsomal but not lysosomal glucuronidase and that a mutant lacking egasyn is deficient in microsomal, but not lysosomal, glucuronidase. By means of a recently developed radioimmunoassay for egasyn, the relationship between microsomal glucuronidase levels and egasyn levels has been examined in various adult tissues, during postnatal development in liver, and after androgen induction of glucuronidase in kidney.

Inheritance in mice of the membrane anchor protein egasyn: the Eg locus determines egasyn levels.

Previous studies have suggested that the binding of mouse flucuronidase to endoplasmic reticulum membrane is stabilized by the membrane protein egasyn. Using a radioimmunoassay for egasyn, we have now examined the inheritance of egasyn levels in mice. Mice of the inbred strain C57BL/6J, which have normal levels of microsomal glucuronidase, contained 56 +/- 10 mug egasyn per gram of liver.

Linkage of genetic determinants for mouse beta-galactosidase electrophoresis and activity.

An electrophoretic polymorphism for beta-galactosidase has been identified among common inbred strains of mice. It is inherited as a single Mendelian factor with two alleles showing codominant expression. This structural gene, Bge, is closely linked (0/163 recombinants) with the Bgs site on chromosome 9 which regulates systemic levels of beta-galactosidase.

Isolation, characterization, and radioimmunoassay of murine egasyn, a protein stabilizing glucuronidase membrane binding.

Glucuronidase present in lysosomes of mouse liver occurs as the free tetramer, whereas glucuronidase present in endoplasmic reticulum occurs in macromolecular complexes containing one to four molecules of the protein egasyn. Earlier genetic and biochemical studies suggest that these complexes, or M forms, function to stabilize the membrane binding of glucoronidase. The detergent Triton X-100 extracts glucuronidase-egasyn complexes intact and they dissociate in the presence of the detergent deoxycholate or upon heating.

Properties of mouse alpha-galactosidase.

alpha-Galactosidase has been examined in various murine tissues using the substrate 4-methylumbelliferyl-alpha-galactoside. Mouse liver appears to contain a single major form of the enzyme, as judged by chromatography and electrophoresis. The enzmye was purified 467-fold with a yield of about 40% by a method involving chromatography on Concanavalin A-Sepharose.

Genetic determination of the alpha-galactosidase developmental program in mice.

The expression of alpha-galactosidase in liver, heart, and brain during postembryonic development has been examined in several inbred mouse strains. In most strains, the developmental patterns of alpha-galactosidase are coordinate with those of two other acid hydrolases, beta-glucuronidase and beta-galactosidase. Certain inbred mouse strains, including members of the C57-C58 family, have a tissue-specific alteration in the temporal expression of alpha-galactosidase activity.