Variants Of Glucose Phosphate Isomerase Research Articles

Combined glucose-6-phosphate dehydrogenase and glucosephosphate isomerase deficiency can alter clinical outcome

Glucosephosphate isomerase (GPI) deficiency in humans is an autosomal recessive disorder, which results in nonspherocytic hemolytic anemia of variable clinical expression. A 4-year-old female with severe congenital hemolytic anemia had low red cell GPI activity of 15.5 IU/g Hb (50% of normal mean) indicating GPI deficiency. Subsequent DNA sequence analysis revealed a novel homozygous 921C to G mutation in the GPI gene sequence, predicting a Phe307 to Leu replacement. Strikingly, the red cell GPI activity in this patient was higher than that found in a second patient expressing the same GPI variant, with a more severe clinical phenotype. We propose that the hemolysis in the first patient may be modified by an accompanying deficiency of glucose-6-phosphate dehydrogenase (G6PD). The proband’s red cell G6PD activity was reduced at 4.5 IU/g Hb (50% of normal mean) and molecular studies revealed heterozygosity for the G6PD Viangchan mutation and a skewed pattern of X-chromosome inactivation, producing almost exclusive expression of the mutated allele. The G6PD Viangchan variant is characterised by severe enzyme deficiency, but not chronic hemolysis. This study suggests that the metabolic consequences of a combined deficiency of GPI and G6PD might be responsible for a different clinical outcome than predicted for either defect in isolation.

Restoration of a normal reproductive lifespan after grafting of cryopreserved mouse ovaries.

Fresh and frozen ovaries from 10 day old C57BL/6J-Gpi-1(a) mice were grafted orthotopically into ovariectomized B6CBF1 (homozygous Gpi-1(b)) recipients. The recipients were mated with B6CBF1 males. The birth and size of each litter was recorded. The electrophoretic variant of glucose phosphate isomerase was determined for each neonate. Twelve of 13 recipients of fresh ovary and 10 of 12 recipients of frozen ovary were fertile. Of these, 10 (fresh) and eight (frozen) had litters derived from the ovarian grafts only, or from the graft and native ovary. The breeding characteristics of recipients of fresh and frozen grafts were similar. The reproductive lifespan of the recipients of fresh (6.2 litters) and frozen (8.4 litters) grafts was similar to that of unoperated C57BL/6-Gpi-1(a) control females mated with B6CBF1 males (6.3 litters). Litter size was similar in recipients of grafted ovaries (fresh, 5.4 pups/litter; frozen, 6.3 pups/litter) and C57BL/6-Gpi-1(a) females (6.3 pups/litter). The results suggest that cryopreservation per se does not affect the long-term viability of ovarian tissue and provides an option for storing female germ cells. This is the first unequivocal demonstration that a normal reproductive lifespan can be restored by orthotopic grafting of frozen ovary.

Expression and Enzymatic Characterization of Human Glucose Phosphate Isomerase (GPI) Variants Accounting for GPI Deficiency

ABSTRACT: To elucidate the structure-function relationships in glucose phosphate isomerase (GPI), we established an expression system for human GPI as a fusion protein with glutathione S-transferase (GST) in E. coli. The GST-GPI fusion protein showed affinities for the substrates glucose 6-phosphate (G6P) and fructose 6-phosphate (F6P) similar to those of the native enzyme purified from human red blood cells (RBC). We expressed GPI cDNAs with four distinct disease-causing mutations and examined their enzymatic characteristics. Although each mutation caused reduced thermal stability, an amino acid substitution Thr-5→Ile (T5I) exhibited marked thermal instability, suggesting that the amino-terminal of GPI is important for enzymatic stability. Thr-224 seemed not to be an essential residue, since the amino acid substitution Thr-224→Met (T224M) showed normal substrate affinity in spite of a slight decrease in both specific activity and thermostability. Gln-343 and Asp-539 have been shown to be in close proximity to the putative catalytic sites, and the present study showed that both Gln-343→Arg (Q343R) and Asp-539→Asn (D539N) caused impaired substrate affinity; Q343R showed high Km for both G6P and F6P, whereas D539N showed significantly decreased affinity only for F6P. These results suggest that not only reduced enzymatic stability but also impaired kinetics may disturb RBC metabolism of the GPI variants associated with hereditary hemolytic anemia.

Isoenzymes of Eimeria from the domestic fowl: electrophoretic variants among species, strains and clones.

Electrophoretic variation of enzymes in five Eimeria spp. of the domestic fowl, including nine strains, ten single-sporocyst clones and two single-sporozoite clones of E. acervulina, three strains each of E. maxima and E. tenella, two strains of E. praecox and one strain of E. necatrix, were assayed using cellulose acetate electrophoresis. Ten enzymes [aldehyde oxidase (AO), alkaline phosphatase (ALP), amylase (AMY), fumarate hydratase (FUM), glucose-6-phosphate dehydrogenase (G6PDH), glucose phosphate isomerase (GPI), glutamate-oxaloacetate transferase (GOT), isocitrate dehydrogenase (IDH), malate dehydrogenase (MDH) and phosphoglucomutase (PGM)] were analyzed for their ability to distinguish between these species and strains. Enzymatic activity of G6PDH, GPI, IDH, MDH and PGM was detected in all the Eimeria spp. examined. Strains within each species were characterized by the same electrophoretic variant of G6PDH. Electrophoretic variants of GPI and PGM were the most valuable in the identification of inter- and intra-specific variation, particularly in the field strains of E. acervulina and E. tenella. These two enzymes were used to examine single-sporocyst and single-sporozoite clones derived from two strains of E. acervulina. The enzymes in E. maxima appeared to be conserved, showing no variation among strains with the five enzymes detected. Relative mobilities, calculated as described in this paper, were found to be consistent between different electrophoresis runs and may serve as a reference when this medium is used.

Molecular Analysis of Glucose Phosphate Isomerase Deficiency Associated With Hereditary Hemolytic Anemia

We report here two new cases of glucose phosphate isomerase (GPI) deficiency associated with hemolytic anemia and present the results of molecular analysis of the five Japanese GPI variants. A Japanese girl (GPI Fukuoka) had an episode of prolonged neonatal jaundice and at 3 years of age was admitted due to acute hemolytic crisis occurring with upper respiratory tract infection. Red blood cell (RBC) GPI activity was decreased to 11.8% of normal and the reduced glutathione (GSH) level of RBCs was slightly decreased. A 54-year-old Japanese man (GPI Iwate) was hospitalized due to chronic active hepatitis, and compensated hemolysis was noted. RBC GPI activity of the proband was decreased to 18.8%, and the GSH content was about half of the normal mean value. Sequencing of the reticulocyte GPIcDNA showed homozygous missense mutations 1028CAG-->CGG (343Gln-->Arg), 14ACC-->A7C (5Thr-->lle), 671ACG-->A7G (224Thr-->Met), and 1615GAC-->AAC (539Asp-->Asn) in GPI Narita, GPI Matsumoto, GPI Iwate, and GPI Fukuoka, respectively. We also identified GPI Kinki as a compound heterozygote of 1124ACA-->AGA(375Thr-->Arg)/ 1615GAC-->AAC(539Asp-->Asn). Our findings, together with the previous results of other investigators, showed that the GPI gene mutations so far identified were heterogeneous, although most GPI variants had common biochemical characteristics such as heat instability and normal kinetics. Several amino acid substitutions were identified in the proximity of the catalytically important amino acid residues such as Ser/Asp 159/160, Asp341, and Lys518, which have been identified in the structural analysis of the pig GPI. The molecular characterization of human GPI variants, therefore, may provide new insights into the genotype-phenotype correlation of GPI deficiency as well as the structure-function relationship of this enzyme.

GPI Mount Scopus — a variant of glucosephosphate isomerase deficiency

Glucosephosphate isomerase (GPI) deficiency is an unusual cause of hereditary nonspherocytic hemolytic anemia. The disease, inherited as an autosomal recessive disorder, is most often manifested by symptoms and signs of chronic hemolysis, ameliorated by splenectomy. We recently diagnosed GPI deficiency in a 23-year-old Ashkenazi Jewish man who displayed the typical clinical course of this disorder. The biophysical characteristics of the GPI variant are slow electrophoretic mobility, presence of only one of the two bands normally present, and extreme thermolability. To the best of our knowledge, this is the first report of GPI deficiency in a patient of Jewish descent, and we propose to designate this enzyme variant "GPI Mount Scopus".

Developmental Potential of Hematopoietic Stem Cells Determined Using Retrovirally Marked Allophenic Marrow

Genetic markers of two general types have been used to assess the number of simultaneously productive stem cells in vivo, retrovirus markers and enzyme or hemoglobin variants. Use of the two techniques has led to different conclusions regarding stem-cell population organization, kinetics, and usage. To better understand this discrepancy, we have combined the two methods by retrovirally marking and transplanting stem cell populations of allophenic mice in which all tissues, including the hematopoietic system, are chimeric. Hematopoietic and lymphoid tissues of engrafted recipients were analyzed by Southern blotting to determine the number and extent of participation of individually marked stem cells. Genotypic chimerism of the same tissues was determined by quantitating electrophoretic variants of glucose phosphate isomerase. This procedure permitted the genotypic identification of individual stem-cell clones. The results demonstrate the participation of few pluripotent stem cells in the repopulation and maintenance of engrafted hematopoietic and lymphoid tissues. Furthermore, stem cells used during the period of early engraftment tended to be of one genotype (DBA/2), whereas stem cells used for long-term maintenance tended to be of the other, coexistent genotype (C57BL/6). We propose that this genotypic specificity reflects functional differences in stem-cell subpopulations and their relative prevalence in different mouse strains suggests a genetic component in the organization and usage of stem cells.

Developmental potential of hematopoietic stem cells determined using retrovirally marked allophenic marrow

Genetic markers of two general types have been used to assess the number of simultaneously productive stem cells in vivo, retrovirus markers and enzyme or hemoglobin variants. Use of the two techniques has led to different conclusions regarding stem-cell population organization, kinetics, and usage. To better understand this discrepancy, we have combined the two methods by retrovirally marking and transplanting stem cell populations of allophenic mice in which all tissues, including the hematopoietic system, are chimeric. Hematopoietic and lymphoid tissues of engrafted recipients were analyzed by Southern blotting to determine the number and extent of participation of individually marked stem cells. Genotypic chimerism of the same tissues was determined by quantitating electrophoretic variants of glucose phosphate isomerase. This procedure permitted the genotypic identification of individual stem-cell clones. The results demonstrate the participation of few pluripotent stem cells in the repopulation and maintenance of engrafted hematopoietic and lymphoid tissues. Furthermore, stem cells used during the period of early engraftment tended to be of one genotype (DBA/2), whereas stem cells used for long-term maintenance tended to be of the other, coexistent genotype (C57BL/6). We propose that this genotypic specificity reflects functional differences in stem-cell subpopulations and their relative prevalence in different mouse strains suggests a genetic component in the organization and usage of stem cells.

Nuclear transfer from teratocarcinoma cells into mouse oocytes and eggs

A spontaneous ovarian teratocarcinoma was isolated from a LT/Sv mouse female and converted into an ascites tumor from which embryonal carcinoma (EC) cells were dissociated. Non-enucleated and enucleated, activated oocytes were fused with EC cells and either cultured in vitro or transferred into ligated oviducts of Swiss/A females. The nucleocytoplasmic hybrids cultured in vitro up to 22 h were examined cytologically at various time intervals. EC nuclei showed morphological remodelling in the foreign cytoplasm. EC chromosomes and female pronuclear chromosomes together formed a common metaphase. The nucleocytoplasmic hybrids developed in vivo were analyzed cytologically between the first and third day after oviduct transfer. The majority of embryos developed abnormally and, in a few instances, they had passed several cleavage divisions and reached, at best, a developmental stage resembling a premature morula. Fertilized, enucleated eggs were fused with EC cells or microinjected with EC nuclei. The resulting nucleocytoplasmic hybrids were either cultured in vitro or in vivo up to the fourth day. Enzyme tests were carried out on the nuclear transplant embryos, using electrophoretic variants of glucose phosphate isomerase (GPI) in order to distinguish between EC nuclei (GPI-A) and recipient eggs (GPI-B). The EC-specific GPI could be detected in about one third of the embryos analyzed and, in several instances, also together with the egg-specific GPI. Most of them were arrested during early cleavage divisions. Some embryos cleaved abnormally or mimicked normal embryogenesis. In a few instances, development resulted in embryos that resembled late preimplantation embryos.

Electrophoretic variants of enzymes in isolates of Plasmodium falciparum, P. malariae and P. vivax from Thailand

A new electrophoretic variant of glucose phosphate isomerase (GPI), which we now denote GPI-3, has been found in isolates of Plasmodium falciparum from 6 patients, all of whom acquired the infection in the same region (in or near Prachinburi province) of Thailand. In other regions, from which 453 isolates have been tested, only GPI-1 and/or GPI-2 have been found. Two isolates of P. malariae from patients at Kanchanaburi showed a band of GPI activity on cellulose acetate gels at a cathodal position quite distinct from that of any previously known GPI variants in other human malaria parasites. Thirtynine isolates of P. vivax from 3 regions of Thailand have been examined for variants of GPI and lactate dehydrogenase (LDH). Three forms of GPI were found, corresponding approximately in band positions to GPI-1, 2 and 3 of P. falciparum. The position of the band of LDH activity in P. vivax was the same in all the isolates examined, and different from that of LDH-1 in P. falciparum.

A new allele of glucose phosphate isomerase in dogs.

A new variant of red cell glucose phosphate isomerase (GPI), designated GPI-C, was observed in the chow-chow breed of dog. GPI-C could be separated from the previously reported dog GPI variants (A and B), both by starch gel electrophoresis and by isoelectric focusing (pH 3-10). Family data supported the hypothesis that GPI-C is controlled by a third codominant allele (GPI C). GPI C occurred as a rare allele in the Dutch chow-chow population.

Glucose phosphate isomerase variants in human bloodstains and seminal stains

Glucose phosphate isomerase (GPI) variants occurring in human red cells were also demonstrated in human semen. Phenotyping was possible from bloodstains of 6 weeks storage and seminal stains of 12 weeks storage. The GPI system may be a supplemental tool for medicolegal individualization of seminal stains.

A third variant of glucose phosphate isomerase in pigs.

A new variant of glucose phosphate isomerase (GPI), also known as phosphohexose isomerase (PHI), was detected in a primitive pig population.

Developmental fate in chimeras derived from highly asynchronous murine blastomeres.

The developmental fate of single blastomeres from eight-cell murine embryos reaggregated with intact two-cell embryos was evaluated after culture. Fluorescein isothiocyanate was used to follow developmental fate in preblastocyst chimeric embryos. Expression of stage-specific embryonic antigen 3 was used to assay developmental fate at the blastocyst stage, and glucosephosphate isomerase variants were used to assay at the blastocyst stage and after implantation. The results suggest that the descendents of the 1/8 component stay in a patch area and do not selectively migrate to the inner cell mass (ICM). This is in contrast to many studies that indicate that smaller blastomeres, which are more advanced in development, migrate to the ICM. The differences in experimental designs are discussed. Possible mechanisms for this phenomena are that the eight-cell blastomere is physically excluded from the ICM by position or polarization, or that it is differentiating ahead of the two-cell component and becomes trophectoderm.

Determination of enzyme variants of glucose phosphate isomerase in Plasmodium falciparum by isoelectric focusing and polyacrylamide electrophoresis

Numerous Plasmodium falciparum isolates from different areas of the world were examined for glucose phosphate isomerase variants by isoelectric focusing and polyacrylamide electrophoresis. The results demonstrate that both methods are required for a comprehensive description and sufficient understanding of glucose phosphate isomerase polymorphism, and isoelectric focusing and polyacrylamide electrophoresis are superior to previously reported electrophoretic techniques for enzymatic analysis of malarial isolates. Conventional acrylamide gel electrophoresis resolved five electrophoretic variants consisting of two phenotypes. Polyacrylamide isoelectric focusing showed three- and six-band electrophoretic patterns. A mixture of three ranges of ampholytes gave optimum resolution. The glucose phosphate isomerase banding patterns showed intraregional variation since both phenotypes were found in the same region. Similar enzyme patterns were found in isolates from different parts of the world.

Enzyme markers for Vibrio cholerae: identification of classical, El Tor and environmental strains

Enzyme electrophoretic variants were studied in 49 strains of Vibrio cholerae using zymovar analysis. The following seven enzymes were selected for use: alanine dehydrogenase (ADH), isocitrate dehydrogenase (IDH), malate dehydrogenase (MDH), phosphoglucomutase (PGM), glucosephosphate isomerase (GPI), 6-phosphogluconate dehydrogenase (6PGDH) and glucose-6-phospate dehydrogenase (G6PDH). The results indicated the presence of three main groups defined chiefly by their GPI and 6PGDH variants. The first group, defined by possessing the variants GPI-2 and 6PGDH-3, contained all the 01 serovar and ElTor biovar isolates from cholera cases. The second group, defined by possessing the variants GPI-3 and 6PGDH-2, contained all the 01 serovar and classical biovar isolates; the third group was heterogeneous and included the 01 serovar isolates from environmental sources as well as isolates of other serovars (the so called NAGs, non-agglutinable with 01 antisera or NCVs). It is thus now possible to separate the epidemic strains of 01 serovar from other members of this serovar isolated from the environment. Zymovar analysis deals with differences which are a direct expression of the genome and seems to be unaffected by gross phenotypic changes such as smooth-rough variation and phage resistance. It is a promising tool for investigating bacteriological and epidemiological questions, in particular the significance of an environmental reservoir of cholera.

Developmental interactions of cells mutant for Strong's luxoid gene with normal cells in chimeric mice

Mouse chimeras were made by fusing embryos from the albino BALB/cFo normal skeleton strain producing a slow variant isozyme of glucose phosphate isomerase (GPI) with embryos from the black pigmented SH strain carrying Strong's luxoid gene (symbol: 1st) for skeletal anomalies and producing a fast GPI variant. All chimeras were estimated to bALB/cFo mice to determine the mosaic status of their gonads. In addition, the quantitative proportions of BALB/cFo and SH cells in skin and limb muscles of chimeras were determined by visual estimation of the degree of coat pigmentation and by a serial dilution method applied to electrophoresis and GPI isozyme reaction of limb muscle homogenates. Skeletons of all chimeras and of representative samples of BALB/cFo and SH mice were examined and graded for expression of a number of normal and mutant skeletal characteristics. The most important conclusion of this study is that there was a definite quantitative effect on the development of skeletal characteristics exerted by the relative amount of BALB/ cFo and SH cells present in a chimera such that a structure could vary from normal to entirely mutant, depending on the proportion of each type of cell present.

An electrophoretically detectable modification of glucosephosphate isomerase in mouse spermatozoa.

Cellulose acetate electrophoresis of glucosephosphate isomerase (GPI) from mouse testis and spermatozoa revealed a minor band which is not seen in electropherograms of GPI from other tissues. The minor band is associated equally with the two electrophoretic variants of GPI examined. Treatment of tissue extracts with various enzymes, enzyme inhibitors or thiol reagents failed to alter the appearance or position of the minor bands in sperm and testis GPI, or to induce their appearance in GPI from other tissues. No minor bands were seen in electropherograms of testis GPI from immature males, or from males whose testes lack spermatozoa for genetic reasons.

Congenital nonspherocytic hemolytic anemia associated with glucosephosphate isomerase deficiency: variant Paderborn.

The deficient red cell enzyme glucosephosphate isomerase (GPI) was characterized in a patient of German origin who had already been described, with congenital nonspherocytic hemolytic anemia, and in his heterozygous parents. The variant enzyme differs from the known GPI variant enzyme differs from the known GPI variants by the electrophoretic mobility, the thermal stability, and the leukocyte activity. No differences are found between normal GPI and the variant regarding the affinity to fructose-6-phosphate, the pH optimum and the thermal optimum. Since the electrophoretic pattern and the properties of the parenteral GPI are identical the propositus seems to be homozygous for an abnormal allele and not double-heterozygous as some other cases with GPI deficiency are. Recently, immunological studies have shown that the variant differs from other similar variants. According to the birthplace of the patient the variant is called "Paderborn".

Genetic variants of glucose phosphate isomerase (E.C. 5.3.1.9) in canine erythrocytes.

Genetic polymorphism of glucose phosphate isomerase (GPI) was found in the erythrocytes of dogs of six Japanese breeds by using starch gel electrophoresis. Analysis of parentage records of dogs revealed that the phenotypic variation of erythrocyte glucose phosphate isomerase was controlled by one autosomal locus with two codominant alleles, GPIA and GPIB. The allele GPIB was observed in the following breeds: San'in-Shiba, Shinshu-Shiba, Shikoku, Kai and Kishu, but not in Hokkaidoes and Akitas. All the dogs belonging to 25 European breeds, 5 oriental or China-origin (except Japan) breeds examined in this experiments had the genotype constitution GPIA/GPIA, whereas one Dalmation dog was heterozygous GPIA/GPIB.