PIG-A and PIG-H, which participate in glycosylphosphatidylinositol anchor biosynthesis, form a protein complex in the endoplasmic reticulum

Many eukaryotic cell surface proteins are bound to the membrane via a glycosylphosphatidylinositol (GPI) anchor. Assembly of the GPI anchor precursor is a sequential addition of components to phosphatidylinositol (PI) in the endoplasmic reticulum (ER). The first step is the transfer of N-acetylglucosamine (GlcNAc) to PI from UDP-GlcNAc to generate GlcNAc-PI. This simple step, however, is regulated by at least three genes because in both mammals and yeasts, there are three mutants of different complementation classes. To clarify this complexity, we analyzed the products of two cloned human genes, PIG-A and PIG-H. Here we demonstrate 1) that PIG-A is an ER transmembrane protein with a large cytoplasmic domain that has homology to a bacterial GlcNAc transferase and a small lumenal domain; 2) that PIG-H is a cytoplasmically oriented, ER-associated protein; and 3) that they form a protein complex. We also show that part of the small lumenal domain of PIG-A plays an essential functional role in targeting itself to the rough ER. Taken together with the cytoplasmic orientation of GlcNAc-PI, these results indicated that PIG-A and PIG-H are subunits of the GPI GlcNAc transferase that transfers GlcNAc to PI on the cytoplasmic side of the ER.

Rat C6 glioma cell growth is related to glucose transport and metabolism

In order to establish whether growth of glioma cells is associated with glucose transport and metabolism, we investigated expression of the glucose transporter and hexokinase, as well as glucose transport and glucose phosphorylation in rat C6 glioma cells growing at different rates. Rat C6 glioma cells were subcloned to produce four different cell lines (CL1, CL2, CL3 and CL4) differing in growth, differentiation and morphology: CL1 cells were slow-growing with an astrocytic appearance whereas CL4 cells grew rapidly and were small and spindle-shaped. Immunocytochemical analysis using glial fibrillary acidic protein and galactocerebroside antibodies revealed that CL1 and CL4 cells differentiate to astrocytes and oligodendrocytes respectively. Both of these cell lines expressed GLUT1 mRNA predominantly, whereas little GLUT3 mRNA was evident by Northern-blot analysis. The GLUT1 mRNA level was much higher in CL4 than in CL1 cells, and the uptake of 2-deoxy-D-glucose and 3-O-methyl-D-glucose by CL4 cells was markedly higher than that by CL1 cells, indicating a correlation between the growth rate, glucose transporter (GLUT1) level and glucose-transport rate of C6 glioma cells. We then studied glucose metabolism by CL1 and CL4 cells by measuring their hexokinase activities and intracellular concentrations of glucose and ATP. The mitochondrial hexokinase activity of CL4 cells was about three times higher than that of CL1 cells, whereas the cytosolic hexokinase activity of CL4 cells was only about half that of CL1 cells. As the total amount of cellular hexokinase protein in CL4 cells was only slightly higher (about 20%) than that in CL1 cells, the hexokinase protein of CL4 cells was considered to have moved from the cytosol to the mitochondrial membranes. Consistent with the increased mitochondrial hexokinase activity of CL4 cells, the intracellular glucose concentration was undetectable, and the ATP concentration was higher than that of CL1 cells, suggesting that glucose transport is the rate-limiting factor for overall glucose metabolism is rapidly growing C6 cells. Therefore the present data demonstrate that glioma cell growth is related to glucose transport, which is closely associated with glucose metabolism.

Development of a canine chemotherapeutic model with ifosfamide

The purpose of this study was to develop a canine experimental model for neoadjuvant chemotherapy of primary bone tumors with ifosfamide, which is safe and clinically relevant for use in human beings with bone tumors. Our study was divided into two steps, each with four dogs. In the first step ifosfamide was administered for 4 consecutive days in three cycles with 3-week intervals between each cycle. For this first step a daily dosage of 300 mg/m2 of body surface resulted in only moderate leukopenia, whereas a daily dosage of 450 mg/m2 caused severe leukopenia. Therefore, to determine the maximal dose tolerable and to verify the results from step 1, we administered the higher daily dosage of 450 mg/m2 in step 2 for four successive cycles with 3-week intervals. In each step one dog died acutely after the first cycle of chemotherapy. In addition during step 2 one dog died of overwhelming sepsis after the second cycle of ifosfamide. The remaining five dogs survived without other appreciable laboratory abnormalities. Neither hematuria nor proteinuria was observed throughout the course of study, and relevant findings were not observed at autopsy. We determined that 450 mg/m2 was the maximal tolerated dosage of ifosfamide for our regimen, with the dose-limiting factor being myelosuppression, specifically leukopenia. Using this canine model, we can estimate the effect of ifosfamide on bone graft incorporations and the fixation of biologic prostheses that is clinically the most important aspect of limb salvage surgery.

PIG-C, one of the three human genes involved in the first step of glycosylphosphatidylinositol biosynthesis is a homologue of Saccharomyces cerevisiae GPI2

Glycosylphosphatidylinositol (GPI) protein anchors are ubiquitous in eukaryotic cells. GPI anchors are synthesized in the endoplasmic reticulum by actions of ten or more gene products. The first step of the biosynthesis, the transfer of N-acetylglucosamine from UDP-N-acetylglucosamine to phosphatidylinositol, is mediated by at least three genes in mammalian cells (PIG-A, PIG-H and PIG-C) and in yeast (GPI1, GPI2 and GPI3/SPT14/CWH6). PIG-A is homologous to GPI3/SPTI4/CWH6. However, PIG-H has no homology with GPI1 or GPI2. Here we cloned a human homologue of GPI2 and showed that it is PIG-C. PIG-C protein is a 297 amino-acid membrane protein in the endoplasmic reticulum that has 20% amino acid identity with GPI2. Since there are several human EST sequences that have homology to GPI1, our results suggest that four genes are involved in the first step of GPI anchor synthesis in mammalian cells.

Alterations of local cerebral blood flow, phorbol 12,13-dibutyrate binding activity, and histological damage during acute focal ischaemia in rat brain. A pathophysiology of acute focal ischaemia: Part 1

The alterations of the local cerebral blood flow (LCBF), 3H-phorbol 12,13-dibutyrate (PDBu) binding activity were measured, and histological findings were also examined during the closed time course (0, 1, 3, 5, 7 hour) after middle cerebral artery occlusion (MCAO) in rat brain to assess the complex pathophysiology of acute focal ischaemia. From 1 to 3 hours after the start of MCAO, significant (p < 0.01) hyperreactivity of the second messenger system involving PDBu binding may be present, despite low perfusion of LCBF, and severe damage in the striatum whereas sparing almost completely the cortex on histological examination. At 5 hours, the PDBu binding activity increased slightly but not significantly but is reduced markedly at 7 hours after MCAO compared with the control group. The measurement of PDBu binding activity, additionally to measuring the LCBF and observation of the histological change might be a useful indicator in determining the threshold and duration of ischaemia which cause functionally irreversible cell damage in the brain.

Cytochrome oxidase activity during acute focal ischaemia in rat brain. A pathophysiology of acute focal ischaemia: Part 2

An enzyme-histochemical technique was used to examine the changes in cytochrome oxidase activity during acute focal ischaemia in the rat. In the somatosensory cortex, the enzyme activity began to increase significantly (p < 0.01) 1 hour after middle cerebral artery occlusion (MCAO) and continued to increase up to 3 hours, during which ischaemic cell damage was not detected. In the striatum, the enzyme activity increased significantly (p < 0.01) 1 hour after MCAO in the absence of morphological evidence of ischaemic cell damage; a peak activity was reached at 2 hours, and began to decline 3 hours after MCAO when moderate ischaemic change was detected. In both cortical and subcortical areas, the enzyme activity tended to decrease from 4 hours after MCAO, and was reduced to a level similar to or below that of the non-ischaemic hemisphere 5 hours after MCAO, when severe ischaemic damage was demonstrated. The relation of this transient increase of cytochrome oxidase activity in the early stage of acute ischaemia and the hypermetabolism of neuronal cells during ischaemic insult was discussed.

Effect of mizoribine on effector T cell-mediated immune responses in mice

T cells play a principal role in cellular immunity and govern the regulatory mechanism in humoral immunity. Therefore, T cells play a key role as either effectors or regulators in the immune network. Mizoribine (MZR), an immunosuppressive agent, suppresses both humoral and cellular immunity by acting on both T cells and B cells. In this study, we examined the effect of MZR on various effector T cell-mediated immune responses in mice. MZR prolonged skin graft survival and suppressed a localized graft-versus-host reaction (GvHR) and sheep red blood cell (SRBC)-induced delayed-type hypersensitivity (DTH) reaction. In a collagen-induced arthritic mice model, MZR reduced the arthritic index and the swelling of the hind limbs. Furthermore, MZR suppressed both bone damage and histopathological changes in the hind limbs. Interestingly, MZR markedly suppressed the DTH reaction to type II collagen (CII) but had no effect on anti-CII antibody levels in this arthritic model. In these models, effector T cells such as cytotoxic T lymphocyte (CTL) and TDTH cell play an important part in the development of these reactions. It is suggested that MZR inhibited these reactions via the inhibition of the effector T cell-mediated immune response. Therefore, it is also suggested that the suppressive effect of MZR on clinical rejection and autoimmune disease is based on its suppression of the effector T cell-mediated immune response, that is cellular immunity, in addition to humoral immunity.

PIG-B, a membrane protein of the endoplasmic reticulum with a large lumenal domain, is involved in transferring the third mannose of the GPI anchor

Many eukaryotic cell surface proteins are bound to the membrane via the glycosylphosphatidylinositol (GPI) anchor that is covalently linked to their carboxy-terminus. The GPI anchor precursor is synthesized in the endoplasmic reticulum (ER) and post-translationally linked to protein. We cloned a human gene termed PIG-B (phosphatidylinositol glycan of complementation class B) that is involved in transferring the third mannose. PIG-B encodes a 554 amino acid, ER transmembrane protein with an amino-terminal portion of approximately 60 amino acids on the cytoplasmic side and a large carboxy-terminal portion of 470 amino acids within the ER lumen. A mutant PIG-B lacking the cytoplasmic portion remains active, indicating that the functional site of PIG-B resides on the lumenal side of the ER membrane. The PIG-B gene was localized to chromosome 15 at q21-q22. This autosomal location would explain why PIG-B is not involved in the defective GPI anchor synthesis in paroxysmal nocturnal hemoglobinuria, which is always caused by a somatic mutation of the X-linked PIG-A gene.

The efficacy of retrograde infusion with LY231617 in a rat middle cerebral artery occlusion model

BACKGROUND AND PURPOSE

We examined the efficacy of the antioxidant LY231617 administered five hours following middle cerebral artery (MCA) occlusion in rats.

METHODS

The treatment was contrived for a two hour interval. Group A (n = 16) was left untreated. Group B (n = 16) received an intravenous infusion of LY231617. Group C (n = 16) received saline (86 microliters/min) by retrograde infusion of the cerebral vein (RICV). Group D (n = 22) was administered LY231617 (10mg/kg/2 hr) in saline (86 microliters/min) by RICV. Local cerebral blood flow with [14C]-iodoantipyrine and blood-brain transfer constant with 14C-alpha-amino-isobutyric acid were examined. Early ischemic damage was histologically examined with cresyl violet and Luxol fast blue and with triphenyl-tetrazolium chloride.

RESULTS

The results revealed a marked increase in local cerebral blood flow (over 600%, p < 0.01) after RICV with LY231617, with a significant improvement of BBB permeability in rats from group D. Ischemic brain damage measured with Luxol fast blue and triphenyl-tetrazolium chloride methods showed a significant improvement (50-91%) of ischemic damage in group D, as compared to groups B and C.

CONCLUSION

Retrograde infusion of the cerebral vein with LY231617 resulted in a significant amelioration at seven hours post MCA occlusion.

A cardiotonic steroid bufalin-induced differentiation of THP-1 cells. Involvement of Na+, K(+)-ATPase inhibition in the early changes in proto-oncogene expression

Human monocytic leukemia THP-1 cells were induced to differentiate into macrophage-like cells by treatment with cardiotonic steroid bufalin, which was previously shown to interact with the Na+, K+-ATPase with similar kinetics to ouabain, a specific inhibitor of the enzyme. This induction of differentiation was characterized by loss of proliferation, cell adherence, increased ability to reduce Nitro Blue tetrazolium (NBT), and increased expression of interleukin 1 beta (IL-1 beta). During this process, bufalin downregulated c-myb and c-myc expressions and induced c-fos and Egr-1 transcripts. Ouabain also caused similar changes in proto- oncogene expression and induced phenotypic markers of differentiated cells at concentrations comparable to bufalin. The 12-O-tetradecanoyl phorbol-13-acetate resistant THP-1 cell variant, which was unresponsive to this agent as to growth inhibition and proto-oncogene expression, responded to bufalin. The finding that protein kinase inhibitor H7 failed to bufalin-mediated c-fos induction further supports the theory that the signal transduction machinery caused by bufalin is separable from the phorbol ester. The cytotoxic effect of high doses of bufalin apparently disappeared in the medium where Na+ was replaced with choline ions. Furthermore, bufalin failed to induce c-fos expression and to downregulate c-myb transcripts in the low-Na+ medium. These findings indicate that an increased intracellular Na+ concentration resulting from the Na+, K(+)-ATPase inhibition possibly triggers the change in proto-oncogene expression evoked by bufalin.

Masseter muscle activity in bottle feeding with the chewing type bottle teat: evidence from electromyographs

It was reported that the activity of the masticatory muscles is reduced in bottle fed babies. The effects of chewing type bottle teats distributed in Japan on masticatory muscle activity were evaluated. Myoelectric activities of the masseter muscles of 12 babies bottle fed with chewing type bottle teats were recorded and analyzed by the same method as in the previous study. The electromyographic records of 12 breast fed babies and 12 babies bottle fed with regular sucking type bottle teats, which were reported in a previous study, were used as controls. The results show that the masseter muscle activity of babies bottle fed with chewing type bottle teats was similar to that of breast fed babies qualitatively as well as quantitatively. However, activity was visibly different from that of babies bottle fed with sucking type bottle teats, showing significant difference by ANOVA. These data suggest that babies who are ingesting milk from chewing type bottle teats do so with a chewing action similar to that of breast feeding, but very different from that of bottle feeding with sucking type bottle teats. The conclusion was that the chewing type bottle teat is useful for establishing masseter muscle activity.

Testicular toxicity of gallium arsenide, indium arsenide, and arsenic oxide in rats by repetitive intratracheal instillation

The testicular toxicities of two compound semiconductor materials, gallium arsenide (GaAs) and indium arsenide (InAs), and arsenic oxide (As2O3) were examined in rats by repetitive intratracheal instillation of these substances in suspension twice a week, a total of 16 times. A single instillation dose was 7.7 mg/kg in the GaAs and the InAs groups and 1.3 mg/kg in the As2O3 group. A significant decrease in sperm count and significant increase in the proportion of morphologically abnormal sperm were found in the epididymis in the GaAs group. Especially, abnormal sperm with a straight head increased markedly in this group. In the GaAs-treated rats, there was 40-fold increase in the degenerating late elongated spermatids at the postspermiation stages, stages IX, XI, and XI. From these results, it is indicated that GaAs disturbed the spermatid head transformation at the late spermiogenic phases and caused spermiation failure. InAs caused a sperm count decrease in the epididymis, though its testicular toxicity was relatively weak compared with that of GaAs. As2O3, a probable dissolution arsenic product of GaAs and InAs in vivo, did not show any testicular toxicities in this study. It seems likely that, along with arsenics, gallium and indium play a role in the testicular toxicities of GaAs and InAs.

Cellular content of p53 protein in rat skin after exposure to the space environment

The effects of stress in space, microgravity and space radiation, on living organisms are still unknown. We have examined the cellular content of p53 protein, a tumor-suppressor gene product, in skin from rats by the Western blot method using a blotting-amplification system. Three groups of rats were used. The first group was kept on Earth normally and showed hardly any detectable p53 protein. The second group made a 14-day flight into space on the second Spacelab Life Sciences-2 mission (F). The last group was subjected to the same kinds of stress as the rats in the second group except for spaceflight (SC). The F and the SC rats were killed on day zero (F-0 and SC-0 groups) and day nine (F-9 and SC-9 groups) after return. F-0 rats showed marked accumulation of p53 protein, whereas SC-0 rats showed a slight decrease. F-9 and SC-9 rats showed almost the same amount of p53 protein, but F-9 rats showed a slightly higher expression. From these results, it is suggested that the accumulation of cellular p53 protein is induced in rat skin cells by exposure to the space environment.

Shear stress modulates expression of Cu/Zn superoxide dismutase in human aortic endothelial cells

A major determinant of the level of cellular superoxide anion (O2-.) is the dismutation of O2-. to hydrogen peroxide by the enzyme superoxide dismutase (SOD). Three forms of SOD exist, but in endothelial cells, the major form outside of the mitochondria is the cytosolic copper/zinc-containing superoxide dismutase (Cu/Zn SOD). Since fluid shear stress is an important determinant of the function and structure of endothelial cells in vivo, we examined the effect of laminar shear stress on the expression of Cu/Zn SOD in cultured human aortic endothelial cells. Laminar shear stress of 0.6 to 15 dyne/cm2 increased Cu/Zn SOD mRNA in a time- and dose-dependent manner in human aortic endothelial cells. Shear stress also increased both Cu/Zn SOD protein content and the enzyme activity. Nuclear runon assays showed that nuclei from human aortic endothelial cells exposed to laminar shear stress had a 1.6-fold greater transcriptional activity of the Cu/Zn SOD gene compared with cells not exposed to shear, indicating that an increase in Cu/Zn SOD mRNA induced by laminar shear stress is at least in part mediated by increased transcription. In contrast, shear stress had no effect on Cu/Zn SOD mRNA levels in human aortic smooth muscle cells. These findings show that physiological levels of shear stress increase expression of Cu/Zn SOD in the endothelium. This adaptation to shear stress might augment the effect of locally produced NO. and thereby promote the antiatherogenic and anti-inflammatory properties of the endothelial cell.

Alterations of hepatic drug metabolising system due to dimethylformamide (DMF)

The effect of repeated exposures to N, N-dimethylformamide (DMF) on the liver and the hepatic microsomal monooxygenase system and glutathione metabolizing enzymes were investigated. DMF was administered to Wistar male rats by subcutaneous (s.c.) injection at 1.0 ml/kg body weight (950 mg/kg), 3 times a week for 2 weeks. The gain in the body weight in the DMF group were suppressed compared with the control group at 2 week. The relative weight of the liver, spleen and kidney also appeared to increase in the DMF group as same as in the control group. Hematological examinations showed no changes. Glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT) did not change in the DMF group. Hepatic microsomal protein and cytochrome P-450 did significantly decrease by 30% and 38%, respectively, while there was no change in cytochrome b5, NADPH-cytochrome c reductase and NADH-ferricyanide reductase. Glutathione peroxidase (GPx) activity was not affected by DMF administration, while glutathione reductase (GR) and glutathione S-transferase, (GST) activity were significantly increased by 16% and 64%, respectively. These results indicate that DMF alters tke hepatic drug metabolizing system without significant increase of the serum transaminase levels. These findings may contribute to elucidate the mechanism of DMF hepatotoxicity.

Cloning and characterization of the murine GPI anchor synthesis gene Pigf, a homologue of the human PIGF gene

Many eukaryotic proteins are bound to the plasma membrane via a glycosylphosphatidylinositol (GPI) anchor. Its core backbone, which is conserved in different organisms, is synthesized in the endoplasmic reticulum by the sequential addition of glycan components to phosphatidylinositol. One of the human GPI synthesis genes, PIGF (phosphatidylinositol glycan complementation class F), which is involved late in the synthesis pathway, has been cloned. In this study, we isolated complementary and genomic clones of Pigf, a murine counterpart of PIGF. Pigf encodes a 219 amino acid protein that complements a class F mutation. The Pigf gene consists of six exons spanning 30 kb and was mapped to chromosome 17 at 17E4-E5. These features are very similar to PIGF, thus demonstrating the interspecies conservation of structure, function, gene organization, and genetic locus between these GPI synthesis genes. The results also extend a region in murine distal chromosome 17 that is syntenic to human chromosome 2p16-p22.

Chronic toxicity of indium arsenide and indium phosphide to the lungs of hamsters

Chronic toxicity of indium arsenide (InAs) and indium phosphide (InP) was studied in male Syrian golden hamsters which received InAs or InP particles containing a total dose of 7.5 mg of arsenic or phosphorus by intratracheal instillations once a week for 15 weeks. As a control, hamsters were treated with the vehicle, phosphate buffer solution. During their total life span, the cumulative body weight gain of hamsters in the InAs group was suppressed significantly compared with that in the control group, but not in the InP group when compared with that in the control group. Concerning the histopathological findings of the lung, the incidence rates of proteinosis-like lesions, alveolar or bronchiolar cell hyperplasia, pneumonia, emphysema and metaplastic ossification observed in the InAs or InP group were significantly higher than those observed in the control group. From these results, it would seem that InAs and InP produced severe damage to the lungs of hamsters.

Collagen cross-reactive antigen of Sarcocystis cruzi

Collagen cross-reactive antigenic substance(s) in Sarcocystis cruzi cysts were examined with immunologic techniques using anti-bovine collagen type-specific, but non-species-specific, antibodies. By immunoperoxidase test, anti-bovine collagen type-specific, but non-species-specific, antibodies. By immunoperoxidase test, anti-bovine type IV collagen antibody showed higher reactivity to the cysts than other antibodies tested. Cyst wall rupture was induced by collagenase treatment and digestion was inhibited with EDTA supplementation. With immunoblotting analysis, one band of the cyst extract, which exhibited specific reactivity to anti-bovine type IV collagen antibody, was detected. The band had a molecular weight of approximately 66 kDa. These results suggest that sarcocysts of S. cruzi may be comprised of bovine collagen type IV cross-reactive antigenic substances.

[Immunoglobulin heavy chain variable region(VH) genes in B cell clones producing anti-colon antibodies in ulcerative colitis]

We have established anti-colon antibodies producing B cell clones from the patient with ulcerative colitis, and analyzed the immunoglobulin heavy chain variable region (VH) gene segments of these clones using RT-PCR with VH family specific primers. VH3 family was used by all ten clones from ulcerative colitis that produced anti-colon antibodies, while various VH gene families were used by eight clones from normal controls. By nucleotide sequence analysis, two LPL clones were thought to be derived from a germ line gene segment, VH26. However, other three PBL clones were derived from 22-2B, 9-1 and 1.9-III, respectively. These results suggest the heterogeneity of the colonic antigens that autoantibodies in ulcerative colitis recognize.

Mechanisms by which the surface expression of the glycosyl-phosphatidylinositol-anchored complement regulatory proteins decay-accelerating factor (CD55) and CD59 is lost in human leukaemia cell lines

We have investigated the mechanisms of defects in the glycosyl-phosphatidylinositol (GPI)-anchored complement regulatory proteins delay-accelerating factor (DAF) and/or CD59 in a panel of human leukaemia cell lines that lack surface expression of these proteins: U937 (DAF+/CD59-), CEM (DAF-/CD59+), TALL (DAF-/CD59-) and a substrain of Ramos [Ramos(-)] (DAF-/CD59-). Northern blotting and reverse transcription-PCR revealed that the main cause of the DAF and/or CD59 deficiency is the failure of mRNA expression in most of the cell lines, except in Ramos(-) in which sufficient mRNA for DAF and CD59 was produced. U937, CEM and TALL cells were not defective in GPI anchor formation as assessed by the detection of other GPI-anchored proteins. No gene abnormality corresponding to DAF or CD59 was detected by Southern blotting. Thus the cause of the defects of DAF and/or CD59 in these leukaemia cell lines except for Ramos(-) is virtually undetectable steady-state levels of the relevant mRNA, most likely attributable to lack of transcription in these cell lines. On the other hand, Ramos(-) cells failed to generate a GPI anchor, whereas they normally expressed DAF and CD59 transcripts. The transfection of phosphatidylinositol-glycan class A (PIG-A) cDNA into Ramos(-) cells restored DAF and CD59 expression, indicating that the defective mechanism in GPI anchor formation is similar to that in paroxysmal noctural haemoglobinuria (PNH) cells, i.e. a deficiency of the PIG-A gene product. Thus the mechanisms of the defects of DAF and/or CD59 in human leukaemia cell lines are not uniform, and in most cases are different from that proposed to cause PNH.

Analysis of PIG-A gene in a patient who developed reciprocal translocation of chromosome 12 and paroxysmal nocturnal hemoglobinuria during follow-up of aplastic anemia

The relationships between paroxysmal nocturnal hemoglobinuria (PNH), aplastic anemia (AA), and myelodysplastic syndrome (MDS) are not clear. Here we describe a patient, J20, who developed a reciprocal translocation of chromosome 12 and PNH during follow-up of AA. All metaphases in CD59-deficient bone marrow mononuclear cells had the translocation, whereas none of the CD59-deficient cells had it, indicating that the PNH clone coincided with a cell population bearing the chromosomal aberration. We found a somatic single-base deletion mutation in the PIG-A gene of this patient's peripheral blood cells. This is the first patient with PNH with a PNH clone containing a chromosomal translocation.