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PubMed1977

Maternal inheritance of enzymes in the mealybug Pseudococcus obscurus (Homoptera).

In the mealybug Pseudococcus obscurus Essig (Pseudococcidae) two esterases, a tyrosinase and a mannosephosphate isomerase, exhibited an unusual type of maternal inheritance. Electromorphs (alleles) were transmitted by both parent but segregation was delayed by one generation and full sisters always had the same phenotype. Moreover, for esterase-1, in which three alleles were present, some of the females exhibited all three alleles. Several other polymorphic loci exhibited normal transmission and segregation. This mode of inheritance can be readily explained by assuming that most or all of the enzymes coded for by these loci are produced by the mycetocytes. The mycetocytes house intracellular bacteria-like symbionts and are usually formed by the fusion ofthe polar bodies and one or more cleavage nuclei. For a locus with two alleles exhibiting this type of inheritance, the expected frequencies of the three phenotypes are p3, 3pq an equation is presented for estimating the frequency of alleles from the frequencies of the phenotypes and it is shown that for three samples from wild populations there is a good agreement between the expected and observed frequencies of the phenotypes.

Alleles↗
PubMedDate not supplied

Inherited enzyme variation among JAX strains of domestic rabbits.

Twelve proteins were assayed for electrophoretic polymorphism in inbred and partially inbred JAX strains of the domestic rabbit. Four enzymes (mannosephosphate isomerase, soluble and mitochondrial malic enzyme, and methemoglobin reductase) were determined to be genetically polymorphic.

Animals↗
PubMedDate not supplied

Location of the gene for theta antigen in the mouse. III. The position of Thy-1 relative to Lap-1 and Mpi-1.

The position of the Thy-1 (theta cell surface antigen) locus on chromosome 9 of the mouse was determined relative to the biochemical markers Lap-1 (leucine arylaminopeptidase) and Mpi-1 (mannosephosphate isomerase). Four-point backcrosses using both male and female heterozygotes showed that the order of these loci is Lap-1--Thy-1--Mpi-1. By observing the segregation of alleles at the Mod-1 (cytoplasmic malic enzyme) locus, which is known to lie distal to these three markers, it was possible to show that Lap-1 is at the centromeric end of this gene group. The overall map for this portion of chromosome 9 as determined by these crosses is: Lap-1--5--Thy-1--7--Mpi-1--14--Mod-1.

Animals↗
PubMed1981

The biosynthesis of a mannolipid containing a metabolite of retinoic acid by 3T12 mouse fibroblasts.

Retinol and retinoic acid (RA) increase the adhesive properties of spontaneously transformed mouse fibroblasts (BALB/c 3T12-3 cells) and the incorporation of [2-3H]mannose into cellular glycoconjugates. Therefore we searched for a mannolipid of retinoic acid similar to mannosylretinylphosphate (MRP) in these cells. Radioactively labeled RA was incorporated into a compound of chromatographic characteristics similar to those of standard MRP. This metabolite contained the same 3H:14C ratio as the precursor [11, 12-3H, 15-14C]retinoic acid, demonstrating that no decarboxylation had occurred. A doubly labeled mannolipid was obtained from cells incubated with [2-3H]mannose and [15-14C]retinoic acid. This mannolipid was readily cleaved by mild acid, yielding [3H]mannosephosphate and a compound that migrated as standard anhydroretinol on thin layer of silica gel in toluene:chloroform:methanol (4:1:1) at Rf 0.93. Standard all trans-MRP yields all-trans-anhydroretinol under these conditions. An ion pair reverse phase HPLC system was developed to further characterize the mannolipids obtained from retinol and retinoic acid in 3T12 cells. [15-3H]Retinol and [15-14C]retinoic acid were incorporated into mannolipids that cochromatographed upon HPLC with standard MRP. The mixture of the [15-3H]retinol and [15-14C]retinoic acid derived mannolipids was subjected to mild acid hydrolysis, after purification by HPLC. Nearly 100% of the compounds was hydrolyzed, yielding all-trans-[3H]anhydroretinol and a 14C]labeled product which was eluted from HPLC as a slightly more polar compound than all-trans-anhydroretinol. The retinoic acid-derived mannolipid (MXP) represented approximately 4% of the total radioactivity in the methanolic extract of 3T12 cells incubated for 20 hours in the presence of labeled retinoic acid. However, if the cells were incubated for an additional 20 hours in the absence of the radioactive precursor, MXP represented 40% of the total extracted radioactivity. These results demonstrate that 3T12 cells synthesize mannosylretinylphosphate from retinol and a mannosylretinoidphosphate (MXP) from retinoic acid. These results exclude the possibility of a reduction of retinoic acid to retinol, but suggest that a closely related compound is formed from RA and that this retinol-like compound (X) is incorporated into MXP.

Animals↗
PubMed1973

Chromosome assignments in man of the genes for two hexosephosphate isomerases.

Thirty-seven clones of somatic cell hybrids between human and mouse cells were examined for retention of human chromosomes and expression of human constitutive enzymes. Human glucosephosphate isomerase and chromosome F-19 were retained or lost concordantly, as were human mannosephosphate isomerase and chromosome C-7. The genes for the enzymes are thus assigned to these two chromosomes.

Animals↗
PubMed1983

Cloning, mapping, and expression of the fumarase gene of Escherichia coli K-12.

Two classes of fumarase-transducing phages, lambda fumA and lambda fumB, were isolated from populations of recombinant phages containing HindIII fragments of Escherichia coli DNA; they were isolated by virtue of their ability to complement the metabolic lesion of a fumarase-negative mutant. The strongly complementing lambda fumA phages contained a 6.2-kilobase HindIII fragment encoding: the fumA gene, located at 35.5 min in the E. coli linkage map and expressing the major fumarase activity; the mannosephosphate isomerase gene, manA; and an unidentified gene, g48. The three genes were located relative to the restriction map of the cloned fragment and the genetic linkage map (terC-g48-fumA-manA-uidAoR), their transcription polarities were defined as anticlockwise in the chromosome, and the molecular weights of the corresponding gene products were established: fumA, 61,500; manA, 42,000; g48, 48,000. Organisms containing the fumA gene sub-cloned in multicopy plasmids overproduced fumarase up to 50-fold. The weakly complementing class of transducing phages, lambda fumB, contained several genes in an 8.2-kilobase HindIII fragment, including one (fumB) that determines a minor fumarase activity. Complementation by fumB was only observed in high-copy situations such as transduction plaques and in strains containing a multicopy plasmid in which 40% of normal fumarase activity was detected. The basis for the complementation by fumB was not defined.

Bacteriophage lambda↗
PubMed1989

Mannose toxicity in Ehrlich ascites tumor cells.

Mannosephosphate isomerase (MPI) showed a higher activity than hexokinase (HKM) in its ability to phosphorylate mannose in the spleen, thymus, brain, liver, striated muscles, kidneys, and testes from BALB/c mice. This led to a HKM/MPI ratio of less than 1 in all the organs and tissues mentioned. In contrast, Ehrlich ascites tumor cells obtained from the peritoneum of BALB/c mice had low MPI activity (half of the HKM activity and, therefore, a ratio of 2). Mannose, which is nontoxic to nontumor cells at a concentration of 0.1 M, induced marked in vitro mortality of the tumor cells. Incubation of Ehrlich ascites tumor cells with mannose resulted in a high accumulation of mannose-6-phosphate and a marked depletion of ATP which did not appear when the cells were incubated with glucose. These facts may explain the selective mortality caused by mannose in the tumor cells studied.

Animals↗
PubMed1980

Use of nicotinamide adenine dinucleotide (NAD)-dependent glucose-6-phosphate dehydrogenase in enzyme staining procedures.

Substitution of nicotinamide adenine dinucleotide dependent glucose-6-phosphate dehydrogenase for the nicotinamide adenine dinucleotide phosphate dependent enzyme has produced identical results in a number of enzyme-linked electrophoretic staining procedures. This substitution significantly reduces the cost of staining for adenylate kinase, creatine kinase, glucosephosphate isomerase, mannosephosphate isomerase, phosphoglucomutase, and pyruvate kinase activity by utilizing NAD rather than the more expensive NADP.

Animals↗
PubMed1992

Comparison of isozyme patterns between Spirometra erinacei and Spirometra mansonoides by isoelectric focusing.

No differences were observed in the isozyme patterns of 4 enzymes examined between fresh samples stored at -80 C and samples stored at room temperature for 10 days after lyophilization, which supports the validity of comparing lyophilized samples to fresh frozen tissue. Mature proglottids as well as plerocercoids of Spirometra erinacei from Japan and Australia were indistinguishable by comparison of isozyme patterns after isoelectric focusing. The isozyme patterns of acid phosphatase, glucosephosphate isomerase (GPI), and mannosephosphate isomerase from plerocercoids of Spirometra mansonoides were distinctly different from those of plerocercoids of S. erinacei. The adenylate kinase isozyme patterns of the mature proglottids of S. mansonoides were also distinctly different from those of the mature proglottids and the plerocercoids of S. erinacei. The GPI isozyme pattern of the mature proglottids of S. mansonoides was also distinguishable from the GPI patterns of those of S. erinacei. These electrophoretic data suggest that the S. erinacei from Japan and Australia are closely related, if not identical, but that S. mansonoides is genetically distinct from S. erinacei.

Acid Phosphatase↗
PubMed1984

Enzymatic determination of D-mannose in serum.

A new and simple enzymatic assay for measuring D-mannose in serum is described. Endogenous glucose is eliminated from serum by use of glucose oxidase (EC 1.1.3.4) and catalase (EC 1.11.1.6). D-Mannose concentration is calculated from the increase in NADH formation after mannosephosphate isomerase (EC 5.3.1.8) is added. This increase is a result of coupling the following series of enzymes: hexokinase (EC 2.7.1.1), glucosephosphate isomerase (EC 5.3.1.9), and glucose-6-phosphate dehydrogenase (EC 1.1.1.49, NAD+-dependent). The study included subjects who were healthy volunteers and patients with suspected or proven fungal infections.

Candidiasis↗
PubMed1977

Characterization of beta-D-N-acetylhexosaminidase isoenzymes in man-Chinese hamster somatic cell hybrids.

A series of man-Chinese hamster hybrids were investigated with the use of an anti-Chinese hamster hexosaminidase serum, a specific anti-human hex A serum and an anti-human hex B serum. The expression of human hex A was found to be dependent on the presence of hex B. A heteropolymeric molecule is formed independently of hex B, which consists of Chinese hamster and specific hex A moieties. It has an electrophoretic mobility nearly identical to hex A. A relationship between the absence and presence of the heteropolymeric molecule, mannosephosphate isomerase (MPI), and pyruvate kinase (PK-3), assigned to chromosome 15, was established. With respect to the two locus subunit model, the gene coding for the alpha subunit, specific for hex A, has been localized on chromosome 15.

Acetylglucosaminidase↗
PubMed2000

Induction of apoptosis by mifepristone and tamoxifen in human LNCaP prostate cancer cells in culture.

BACKGROUND: Published data indicate that antiprogestins and antiestrogens could inhibit prostate cancer cell growth in vitro and in vivo. The main objective of the present studies was to explore the role of bcl(2) and TGFbeta(1) for induction of apoptosis in LNCaP prostate cancer cells growing in culture as a treatment response to the antiprogestin, mifepristone, and the antiestrogen, 4-hydroxytamoxifen. METHODS: In vitro cell viability (cytotoxicity), DNA fragmentation, and changes in the expression of bcl(2) and TGFbeta(1) proteins were assessed using the sulforhodamine B protein dye-binding assay, specific ELISA, and competitive inhibition assays. RESULTS: Both steroid antagonists induced a significant time- and dose-dependent cell growth inhibition (cytotoxicity). This inhibition of viable cells was associated with a significant increase in DNA fragmentation (apoptosis), downregulation of bcl(2), and induction of TGFbeta(1) protein. Abrogation of the mifepristone- and 4-hydroxytamoxifen-induced cytotoxicity by TGFbeta(1)-neutralizing antibody and by the addition of mannose-6-phosphate confirmed the correlation between induction of active TGFbeta(1) and subsequent prostate cancer cell death. The effect of mifepristone was not significantly reduced or prevented by occupying the progesterone or glucocorticoid receptors by their corresponding high-affinity native ligands. On the contrary, the effect of a combination of mifepristone with progesterone or hydrocortisone on the increase in DNA fragmentation, bcl(2) downregulation, and induction of TGFbeta(1) protein was additive and significantly different (P < 0.05) from the effect of mifepristone monotherapy. CONCLUSIONS: Our data suggest that mifepristone and tamoxifen are effective inducers of apoptosis and may represent nonandrogen-ablation, novel therapeutic approaches to overcome a potential intrinsic apoptosis resistance of androgen-independent prostate cancer cells.

Animals↗
PubMed1997

Differential targeting and processing of procathepsin D in normal and transformed murine 3T3 fibroblasts.

The kinetics of transport and the processing of procathepsin D (proCD), the precursor of a lysosomal aspartyl protease involved in tumor-cell proliferation and metastasis, were compared in normal and SV-40- or benzo[a]pyrene-transformed 3T3 mouse fibroblasts. Sorting of newly synthesized proCD in normal cells was almost complete within 3 hr, while in transformed cells a fraction of the precursor survives a long time. In both normal and transformed 3T3 cultures, secretion of proCD started at 3 hr of chase. However, in normal cells secretion of proCD remained constant between 3 and 24 hr of chase, while in transformed cells it increased along with the chase incubation. The efficiency of formation of the mannose-6-phosphate group on proCD varied among the 3 cell types, being minimal in benzo[a]pyrene-transformed 3T3 cells. Ammonium chloride, a drug known to disrupt the segregation and to enhance the secretion of lysosomal proenzymes, was 2-fold more effective in normal than in transformed 3T3 cells. Despite vacuolar alkalinization, about one third of proCD was segregated into the endosomal-lysosomal pathway in normal and in transformed 3T3 fibroblasts, indicating the existence in these cells of alternative, mannose-6-phosphate receptor-independent mechanisms for targeting proCD. Thus, while hypersecretion of proCD and reduced sensitivity to vacuolar alkalinization are common features of both transformed cell types, the mechanisms responsible for inefficient segregation of proCD may differ between virally and chemically transformed 3T3 cells.

3T3 Cells↗
PubMed1996

Insulin and the insulin-like growth factors I and II are mitogenic to cultured rat sciatic nerve segments and stimulate [3H]thymidine incorporation through their respective receptors.

The factors that control proliferation of Schwann cells during peripheral nerve regeneration are not yet known. In this study we investigated the effects of insulin, insulin-like growth factor I and II (IGF-I and IGF-II), IGF-I analogues, and factors that interfere with their respective receptors, on [3H]thymidine incorporation into cultured nerve segments from the rat sciatic nerve. Segments cultured in nM (0.1-1.7 nM) concentrations of insulin, truncated IGF-I (tIGF-I), long R3IGF-I, or IGF-II exhibited an increase in [3H]thymidine incorporation compared with control segments. IGF-II was most potent. JB1, an IGF-I antagonist, counteracted the effects of tIGF-I and insulin. The results suggest that non-neuronal cells in the nerve segment, probably Schwann cells, possess distinct receptors for insulin, IGF-I, and IGF-II and that these receptors may be involved in the control of Schwann cell proliferation during peripheral nerve regeneration.

Animals↗
PubMed1998

Role of sialic acid in the endocytosis of prosaposin by the nonciliated cells of the rat efferent ducts.

The present study examines the mechanism of endocytosis of testicular prosaposin by the nonciliated cells of the efferent ducts. Testicular prosaposin is secreted by Sertoli cells into the lumen of the seminiferous tubules as a 70 kDa isomer where it binds to the tail of spermatozoa. In the efferent ducts, after dissociating from the plasma membrane of the spermatozoa, prosaposin is endocytosed by the nonciliated cells, presumably by receptor-mediated endocytosis. The initial step of receptor-mediated endocytosis usually results from the binding of a ligand's terminal oligosaccharide to a receptor on the cell surface. Thus, in the present study, several monosaccharides were injected in the lumen of the efferent ducts to compete with the binding and endocytosis of prosaposin. A quantitative electron microscopic approach was utilized and the number of gold particles, indicating anti-prosaposin immunoreactive sites, were scored over the various cell compartments including the plasma membrane, endocytic vesicles, early endosomes, and late endosomes. The length of the plasma membrane and the areas of endocytic vesicles, early endosomes, and late endosomes were measured with an image analyzer and the number of grains expressed per microm (plasma membrane) and microm2 (endocytic vesicles/endosomes) respectively. The quantitative analysis was performed in untreated animals (controls) and animals treated with various sugars (i.e., glucose, galactose, mannose, mannose 6-phosphate, N-acetylglucosamine and N-acetylgalactosamine) injected into the lumen of the efferent ducts at a concentration of 20 mM. Sialic acid caused the greatest decrease in the labeling density of the endocytic elements. Mannose 6-phosphate also caused a decrease in labeling but to a lesser extent. Various amounts of sialic acid (0.02 mM, 0.2 mM, 2 mM, 20 mM, and 200 mM) showed that most of these concentrations produced a significant decrease in the labeling density of endocytic vesicles and endosomes. Moreover, Western blots of prosaposin isolated from seminiferous tubular fluids followed by glycan analysis with Sambucus nigra agglutinin (SNA) and Maackia amurensis agglutinin (MAA), revealed that this protein has sialic acid residues that are terminally linked to galactose and/or N-acetylgalactosamine (alpha-NeuNAc-[2->6]-Gal and alpha-NeuNAc-[2->6]-GalNAc). These data indicate that testicular prosaposin is removed from the lumen of the efferent ducts by the noncialiated cells via a receptor that recognizes prosaposin's terminal sialic acid residues.

Animals↗
PubMed2000

Towards a human repertoire of monocytic lysosomal proteins.

The lysosomal compartment of human monocytic cells has never been investigated by a proteomic approach. By a combination of one-dimensional (1-D) and two-dimensional (2-D) gel electrophoresis, protein identification by N-terminal sequencing, matrix assisted laser desorption/ionization-mass spectrometry (MALDI-MS) peptide mass fingerprinting and tandem mass spectrometry (MS/MS) peptide sequence analysis, we initiated an exhaustive study of the human lyososomal proteome, which aims at establishing a 2-D reference map of human soluble lyososomal proteins. Human monocytic U937 cells were induced to secrete lysosomal soluble hydrolases by addition of NH4Cl in the culture medium. Since lysosomal soluble proteins are characterized by the presence of mannose-6-phosphate, they were purified on an affinity support bearing mannose-6-phosphate receptor. Analysis of the purified fraction led to the preliminary identification of fifteen proteins, among which twelve are well-known lysosomal hydrolases, one is assumed to be lysosomal on the basis of sequence homology to cysteine proteinases of the papain family, and two (leukocystatin and the human cellular repressor of E1A-stimulated genes) are described here for the first time as mannose-6-phosphate-containing proteins.

Amino Acid Sequence↗
PubMed2002

Proteomic analysis of human lysosomes: application to monocytic and breast cancer cells.

To date, about fifty lysosomal hydrolases have been identified, and most of them are targeted towards the lysosomes through a specific mannose-6-phosphate (M-6-P) tag. As more lysosomal hydrolases were expected to be discovered, we performed a proteomic study of soluble lysosomal proteins. Human cells were induced to secrete M-6-P proteins which were affinity purified on immobilized M-6-P receptor. The purified proteins were resolved by two-dimensional electrophoresis and analyzed by mass spectrometry. Twenty-two proteins were identified, among which 16 were well-known lysosomal hydrolases. The remaining species distributed as follows: epididymis-specific alpha-mannosidase is a new mannosidase homolog, cystatin F and CREG (cellular repressor of E1A-stimulated genes) were previously identified as M-6-P proteins (Journet et al., Electrophoresis 2000, 21, 3411-3419), and the last three, which are not hydrolases, were up to now considered as nonlysosomal. This two-dimensional reference map of human U937 M-6-P proteins was afterwards used for comparison with M-6-P proteins purified either from U937 differentiated into macrophage-like cells, or from human breast cancer MCF7 cells. Phorbol ester induced differentiation of U937 cells led to limited proteolytic cleavage or maturation of a discrete number of hydrolases. Five additional lysosomal hydrolases were identified from MCF7 samples. These results prove the usefulness of such a procedure to analyze the lysosomal content of various cell lines, to discover new M-6-P proteins, as well as to point towards unknown biological processes.

Animals↗