The fourth armadillo repeat of plakoglobin (gamma-catenin) is required for its high affinity binding to the cytoplasmic domains of E-cadherin and desmosomal cadherin Dsg2, and the tumor suppressor APC protein

Plakoglobin is a member of a protein family with a repeated amino acid motif, the armadillo repeat, and is a cytoplasmic protein found in both adherens junctions and desmosomes. Plakoglobin has been shown to form distinct complexes with cadherins or desmosomal cadherins. Also, plakoglobin has been shown to complex with APC, the tumor suppressor gene product. Recently we isolated a cDNA clone encoding plakoglobin lacking the fourth armadillo repeat of the original 13-repeat protein [Ozawa et al. (1995) J. Biochem. 118, 836-840]. In this study, we established an in vitro assay system to study the molecular interaction of plakoglobin with cadherins, the APC gene product, and alpha-catenin. Establishment of the system and cloning of an alternate form of plakoglobin cDNA allowed us to examine the biological activity of plakoglobin lacking the fourth armadillo repeat. Experiments with the bacterially expressed 12-repeat plakoglobin revealed that the protein binds to E-cadherin, desmoglein (Dsg2), and APC with lower affinity than the 13-repeat form does. Consistent with the observation that the affinity of alpha-catenin for these two alternate forms was similar, we found amino acid residues 104 to 145 of plakoglobin, the residues present in both isoforms, are sufficient for its binding to alpha-catenin.

The 8,344 mutation in mitochondrial DNA: a comparison between the proportion of mutant DNA and clinico-pathologic findings

Ten patients, two men and eight women with mitochondrial encephalomyopathy, had an A-G mutation at nucleotide pair 8,344 in the mitochondrial DNA, the most common genetic defect in myoclonus epilepsy with ragged-red fibers (MERRF). Eight patients had the clinical and pathologic characteristics of MERRF including myoclonus, seizures, cerebellar ataxia and myopathy with ragged-red fibers. Two patients had atypical symptoms such as early onset of fatal cardiac failure and late onset of rapid mental deterioration, respectively. The striking feature in our patients with the 8,344 mutation cardiac involvement and two developed progressive heart failure. In the typical MERRF patients, the proportion of mutant mitochondrial DNA in their skeletal muscles, quantified by a single strand conformation polymorphism analysis, was above 85%. However, there was no significant correlation between clinical severity, histopathological findings and the proportion of mutant mtDNA in muscle biopsy samples, suggesting that non-ragged-red fibers play an important role in the phenotype expression of the mutants.

Cloning of an alternative form of plakoglobin (gamma-catenin) lacking the fourth armadillo repeat

Plakoglobin is a member of a protein family with a repeating amino acid motif called the armadillo repeat, and is a cytoplasmic protein found in both adherens junctions and desmosomes. Little is known about its function, but it has been shown to form distinct complexes with cadherins or desmosomal cadherins. Also, plakoglobin has been shown to form a complex with APC, a tumor suppressor gene product. We have isolated a cDNA clone encoding plakoglobin by means of the polymerase chain reaction (PCR) from a human transitional carcinoma cell line. The cDNA has the same nucleotide sequence as the previously published one [Franke et al. (1989) Proc. Natl. Acad. Sci. USA 86, 4027-4031], except that it has a deletion of 120 bp. The deleted sequence encodes the fourth armadillo repeat. Southern blot analysis of genomic DNA revealed that there is a single copy of the plakoglobin gene per haploid genome. Cloning and sequencing of a genomic DNA fragment containing the 120-bp deletion and the surrounding sequences revealed that these sequences are encoded by a single exon sequence. PCR amplification of the genomic DNA fragment of the corresponding region excluded the possible presence of the 120-bp deletion in the gene. Therefore the variant form is most likely derived through alternative splicing of precursor RNA transcripts in an exon sequence.

Structure of the mouse basigin gene, a unique member of the immunoglobulin superfamily

Basigin is a membrane glycoprotein belonging to the immunoglobulin superfamily. The mouse basigin gene was isolated from a genomic DNA library of the BALB/c mouse, and the structure of the gene and its flanking region (11.8 kb) was completely determined. The mouse basigin gene consists of seven exons and six introns spanning 7.5 kb. The distance between the first and second exons is 5.1 kb. The first immunoglobulin-like domain of the basigin molecule is encoded by the second and third exons, and the second immunoglobulin-like domain by the fourth and fifth exons. The fifth exon encodes not only the C proximal portion of the second immunoglobulin-like domain, but also the transmembrane domain and a small portion of the cytoplasmic domain. Thus, the organization of the basigin gene is unique. The 5' upstream sequence of the basigin gene contains no TATA box or CAAT box, but has a CpG-rich island. The BALB/c genomic sequence of all seven exons is consistent with the cDNA sequences of the 129/SV and Swiss mice except several minor substitutions in the 3'-terminal sequence of the 3'-noncoding region. No protein polymorphism has so far been found in basigin of different mouse strains.

A novel point mutation in the mitochondrial tRNA(Ser(UCN)) gene detected in a family with MERRF/MELAS overlap syndrome

We found a new point mutation in the mitochondrial tRNA(Ser(UCN)) gene in a family with MERRF/MELAS overlap syndrome by screening for heteroplasmy by means of chemical cleavage of mismatch (CCM). Our strategy was based on the previous observations that most pathogenic mtDNA mutations in mitochondrial encephalomyopathies are heteroplasmic, whereas almost all neutral mitochondrial polymorphisms are homoplasmic. CCM followed by nucleotide sequencing of the corresponding region of the mitochondrial genome revealed a heteroplasmic mutation at nt 7512 in the tRNA(Ser(UCN)) gene. The 7512 (T to C) mutation disrupts a highly conserved base pair in the acceptor stem, and this mutation was not found in any of 120 normal controls, or in 43 patients with mitochondrial diseases. The proportion of the mutant mtDNA was 93% in muscle, 76 and 87% in the blood of the patients. A family member without apparent neuromuscular symptoms carried less mutant mtDNA. These findings support the view that this mutation is pathogenic in this family. Detection of heteroplasmy by CCM is an efficient means of screening pathogenic mtDNA point mutations.

Changes in c-Kit expression and effects of SCF during differentiation of human erythroid progenitor cells

We analysed c-Kit expression during erythroid differentiation using immunocytochemical staining and flow cytometric analysis. Burst-forming units-erythroid (BFU-E)-derived cell aggregates were identified in methylcellulose cultures containing human umbilical cord blood CD34+ cells and were stained by the indirect immunoalkaline phosphatase method. To investigate the changes in levels of cell-surface c-Kit expression, we subjected progenitor cells in liquid culture to flow cytometric analysis. In addition, the effects of stem cell factor (SCF) on cell-surface c-Kit expression were analysed in these two culture systems and the effects of SCF on erythroid colony formation were studied in a methylcellulose culture. c-Kit was expressed on the cell surface from BFU-E to erythroid precursors recognized morphologically as basophilic erythroblasts. Flow cytometric analysis showed that c-Kit expression increased until 6 d in liquid culture, and that decreased expression of c-Kit was associated with the increased expression of glycophorin A. Moreover, SCF increased the size of erythroid colonies when added at days 0, 4 and 8 in methylcellulose cultures. These results indicate that the c-Kit/SCF system still plays in proliferation of erythroid progenitor cells at the colony-forming units-erythroid stage. Finally, expression of c-Kit in erythroid progenitor cells cultured without SCF showed a diffuse pattern on the cell surface, whereas we observed positive c-Kit immunoreactivity in the region of the Golgi apparatus of these cells cultured with SCF. Flow cytometric analysis also showed that the levels of cell-surface c-Kit expression decreased in the presence of SCF. These results suggest that SCF induced down-modulation of cell-surface c-Kit expression, despite continuous synthesis of c-Kit protein.

cDNA cloning and sequence analysis of a novel calcium binding protein with oligoproline motif

Using antibodies against pokeweed agglutinin-binding proteins from F9 embryonal carcinoma cells, we isolated a cDNA clone PW29 reacting with the antibody. mRNA hybridizing with the cDNA was 4.7 kb, and was strongly expressed in the testis, brain, kidney and heart as well as in F9 cells. The size of mRNA in the testis was heterogeneous. Sequencing the cDNA clone revealed a putative polypeptide of 70 kDa, which is rich in hydrophilic amino acids and has a characteristic sequence of (Glu(Lys))5. The protein also has an oligoproline motif, which conforms to the rule of binding capability to Src homology region III. The cDNA was translated as a fusion protein with glutathione-S-transferase, and was verified to have calcium binding activity, upon a calcium blot experiment.

Midkine (MK) expression in extraembryonic tissues, amniotic fluid, and cerebrospinal fluid during mouse embryogenesis

Midkine (MK) and pleiotrophin (PTN) constitute a new family of heparin-binding growth factors. Extraembryonic membranes and the placenta of the mouse expressed MK mRNA at 11.5 days gestation. While the MK mRNA level in extraembryonic membranes decreased during embryogenesis, that in the placenta remained unchanged. Immunohistochemical studies showed that Mk was located in the yolk sac and in the amnion at 11.5 days gestation. PTN mRNA expression was weak in extraembryonic membranes and was scarcely detectable in the placenta. Western blot analysis revealed the presence of MK in amniotic fluid and cerebrospinal fluid, in amounts of more than 1 microgram/ml, raising the possibility that MK delivered by these fluids participates in the regulation of organogenesis. Transport of MK from the site of its synthesis appears to also occur in the adult kidney, since MK mRNA and the MK protein are localized in different regions of the kidney.

Magnetic resonance images reveal a high incidence of asymptomatic pineal cysts in young women

MACROSCOPIC BENIGN PINEAL cysts, according to previous reports, may preferentially occur in the young population at the fourth decade; symptomatic pineal cysts have been found mainly in females. To confirm the relationship of age and sex to the incidence of pineal cysts, we reviewed 8623 consecutive magnetic resonance images in 6023 patients. Tiny and obscure cysts in the pineal gland were ignored; only the pineal cysts > 5 mm were examined. The cysts were encountered in 79 (1.3%) of 6023 patients evaluated. The cysts predominantly occurred in females; we found 29 cysts in 3008 males and 50 cysts in 3015 females (P < 0.05). Young adults had higher incidence of these cysts, with a peak incidence occurring between the ages of 21 and 30 years, then the incidence gradually decreased with age. We found no significant age distribution in males. However, among all groups, young women between the ages of 21 and 30 years had the highest frequency (5.82%). The incidence of pineal cysts among women between the ages of 21 and 30 years was significantly higher than in any other group (P < 0.001; 21-30 versus 51-60, 61-70, and 71-80). In females, when the incidence below the age of 41 was compared with that above or equal to 41, the z score was 4.98 (P < 0.001). The cystic expansion of the pineal gland in females appeared to begin at adolescence, and presumably the pineal gland decreases in size with aging. In this article, we will also speculate about the relationship of these changes to the secretory activity of the pineal glands.

Analysis of the nucleotide sequence of chromosome VI from Saccharomyces cerevisiae

The complete nucleotide sequence of Saccharomyces cerevisiae chromosome VI (270 kb) has revealed that it contains 129 predicted or known genes (300 bp or longer). Thirty-seven (28%) of which have been identified previously. Among the 92 novel genes, 39 are highly homologous to previously identified genes. Local sequence motifs were compared to active ARS regions and inactive loci with perfect ARS core sequences to examine the relationship between these motifs and ARS activity. Additional ARS sequences were predominantly observed in 3' flanking sequences of active ARS loci.

Structure of the gene encoding mouse reticulocalbin, a novel endoplasmic reticulum-resident Ca(2+)-binding protein with multiple EF-hand motifs

Reticulocalbin, an endoplasmic reticulum (ER)-resident Ca(2+)-binding protein, is a member of the EF-hand Ca(2+)-binding protein superfamily [Ozawa, M. and Muramatsu, T. (1993) J. Biol. Chem. 268, 699-705]. Reticulocalbin has six repeats of a domain containing the EF-hand motif. In addition, the protein has an amino-terminal leader sequence which serves as a signal for transfer of the protein into the lumen of the ER, and a His-Asp-Glu-Leu sequence at its carboxy terminus which functions as a signal to retain the protein in the ER. In this paper, we describe the genomic structure of this unique Ca(2+)-binding protein. Southern blot analysis of mouse genomic DNA revealed that there is a single copy of the reticulocalbin gene per haploid genome. The gene spans over 13 kilobase pairs and encodes six separate exons. Thus, reticulocalbin differs from the cytosolic Ca(2+)-binding protein calbindin D28 which also has six EF-hand motif domains, but the gene for which is divided into 11 exons. While there is some correlation between exon division and protein domain structure, these relationships are not as clear as they are in other genes. Comparison of the gene organization of reticulocalbin with that of other EF-hand proteins revealed that reticulocalbin diverged very early from other members of the EF-hand protein super-family.

Increased midkine gene expression in human gastrointestinal cancers

Midkine (MK) is a product of a retinoic acid-responsive gene, and is a novel growth differentiation factor. We examined the expression of the MK gene in specimens of 47 surgically removed human carcinomas of the gastrointestinal organs, namely, gastric, colorectal, hepatocellular, pancreatic, esophageal, ampullary duodenal and bile duct carcinomas. In most cases, the MK mRNA level was higher in cancer specimens than in the corresponding non-cancerous tissues. Furthermore, MK mRNA was more highly expressed in the colon adenocarcinoma lesion than in the adenoma lesions, in the two familial polyposis cases. While MK mRNA was not detected in the normal liver, it became detectable in cirrhotic tissues in 2 of 4 cases, and its expression was increased in the cancerous tissues. Thus, the increase of MK mRNA level is a phenomenon seen in many human gastrointestinal carcinomas. The increased expression of the MK gene in gastric carcinoma was significantly more prominent in well and moderately differentiated adenocarcinomas than in poorly differentiated adenocarcinomas and signet ring cell carcinomas.

Clinical efficacy of pravastatin for hyperlipidemia in patients with type 2 diabetes mellitus

The efficacy of pravastatin (CAS 81131-70-6) on serum lipid levels in 91 type 2 diabetic patients with mean glycosylated hemoglobin of 8.5% was investigated up to 12 weeks. Oral administration of 10 to 20 mg/d of pravastatin significantly decreased total cholesterol by 18.4 +/- 1.5% after 4 weeks. When analyzed separately in type IIa and IIb hyperlipidemia, the reduction of total cholesterol by pravastatin was more prominent in the former. Low-density lipoprotein cholesterol were also significantly decreased 22.2 +/- 2.7% after 4 weeks. The effect of pravastatin in reducing triglyceride was more prominent in patients with higher triglyceride compared to those with lower triglyceride before the administration of the drug. High-density lipoprotein cholesterol showed a slight but significant increase by 4.2 +/- 1.9% after 4 weeks. Among the apolipoproteins examined, apolipoprotein B was significantly decreased after 4 weeks. Atherogenic index and apolipoprotein B/apolipoprotein A-I ratio were also significantly decreased after 4 weeks. The efficacy of pravastatin was also observed after 12 weeks to the same extent as after 4 weeks. No major side effects or abnormalities of laboratory parameters have been observed. These data lead to the conclusion that pravastatin is useful for the treatment of hyperlipidemia in type 2 diabetic patients with poor glycemic control without major adverse effects.

Cloning of a human homologue of mouse reticulocalbin reveals conservation of structural domains in the novel endoplasmic reticulum resident Ca(2+)-binding protein with multiple EF-hand motifs

Recently, we described the isolation of a mouse cDNA clone encoding a novel Ca(2+)-binding protein, tentatively designated as reticulocalbin [Ozawa, M. and Muramatsu, T. (1993) J. Biol. Chem. 268, 699-705]. Reticulocalbin is a lumenal protein of the endoplasmic reticulum (ER) with a molecular weight of 44,000 and has six repeats of a domain containing the high affinity EF-hand Ca(2+)-binding motif. The protein has the sequence, His-Asp-Glu-Leu (HDEL), at its carboxy terminus, which serves as a signal for its retention in the ER of cells. To examine the importance of the putative Ca(2+)-binding domains as well as the carboxy-terminal HDEL sequence, we have cloned the human homologue of reticulocalbin. The sequence of this clone revealed a novel protein with 95% identity in amino acid sequence to the mouse reticulocalbin, indicating that this molecule has been evolutionarily conserved in mammals. As was found for the mouse reticulocalbin, the human homologue showed six repeats of a domain containing EF-hand motifs. Interestingly, conservation of the amino acid sequence was not restricted to the Ca(2+)-binding motifs, consistent with the possibility that reticulocalbin plays some role(s) besides Ca(2+)-binding. As was found for the mouse homologue, the protein has the HDEL sequence at its carboxy terminus instead of the Lys-Asp-Glu-Leu (KDEL) sequence, which is more common as a signal for the retention of resident proteins in the ER of animal cells. The conservation of the HDEL sequence in reticulocalbin in both species raises the possibility that this sequence has some roles in the function(s) of this protein family.

CBP-140, a novel endoplasmic reticulum resident Ca(2+)-binding protein with a carboxy-terminal NDEL sequence showed partial homology with 70-kDa heat shock protein (hsp70)

Antibodies against pokeweed agglutinin binding proteins isolated from F9 embryonal carcinoma cells were used to screen a lambda gt11 expression library constructed from the cells. A cDNA clone thus obtained encoded a novel calcium binding protein of 140 kDa (CBP-140). Antibodies raised against the CBP-140 fusion protein stained a 140 kDa band in extracts not only from F9 cells but also from various mouse organs. A calcium blot experiment using CBP-140 fusion protein verified the calcium binding property of the protein. In the partial amino acid sequence so far clarified (652 amino acid residues) we could not detect EF-hand, but could detect contiguous acidic amino acids, which may serve as a calcium-binding site. CBP-140 showed homology with 70-kDa heat shock protein, though it was not induced by heat shock treatment. Localization of CBP-140 in endoplasmic reticulum was shown by indirect immunofluorescence staining and also by subcellular fractionation. Amino acid sequence of CBP-140 contains a carboxyl-terminal Asn-Asp-Glu-Leu (NDEL) sequence, which resembles Lys-Asp-Glu-Leu (KDEL) sequence, a signal to retain the resident proteins in endoplasmic reticulum; NDEL sequence may indeed play a similar role.

Relationship between morphological classification of the degree of maturation and the ploidy of micromegakaryocytes in myelodysplastic syndrome patients

To clarify the biological behavior of micromegakaryocytes in myelodysplastic syndrome (MDS), the relationship between the morphological classification and the ploidy of megakaryocytes was studied in bone marrow aspirates obtained from patients with MDS and from normal controls. The morphology was determined according to Feinendegen's classification, which is considered to reflect megakaryocytic maturation, and the ploidy was determined by microcytofluorometry, using 4',6-diamidino-2-phenylindole (DAPI) staining after the removal of Wright-Giemsa stain. Most micromegakaryocytes (i.e., megakaryocytes < 20 microns in diameter) in MDS were morphologically mature, as were those in the normal controls. The peak micromegakaryocytic ploidy was 4N or 8N, whereas that of the megakaryocytes in normal controls was 16N. These findings indicated that the micromegakaryocytes in MDS were morphologically mature but had impaired polyploidization.

Combination treatment of the partial D2 agonist terguride with the D1 agonist SKF 82958 in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-lesioned parkinsonian cynomolgus monkeys

The optimal combination of a dopamine D2 agonist and a D1 agonist was evaluated for symptomatic treatment of Parkinson's disease. Behavioral effects of combination treatment of the full D2 agonist quinpirole or the partial D2 agonist terguride with the full D1 agonist SKF 82958 [(I) 6-Chloro-7, 8-dihydroxy-3-allyl-1-phenyl-2, 3, 4, 5-tetra-hydro-1H-3-benzazepine] were investigated in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned parkinsonian cynomolgus monkeys with attention to the induction of hyperactivity such as irritability, excitability and aggressiveness and of dyskinesias such as licking of paws, chewing and biting. Both quinpirole and SKF 82958 alone improved the parkinsonism with a slight induction of the hyperactivity and dyskinesias. Terguride also improved the parkinsonism but did not induce the hyperactivity and dyskinesias. Combination treatment of quinpirole with SKF 82958 not only showed a tendency to augment the antiparkinsonian effects but also induced the marked hyperactivity and dyskinesias. On the other hand, combination treatment of terguride with SKF 82958 also augmented the antiparkinsonian effects but did not induce any hyperactivity and dyskinesias. These findings suggest that combination therapy with a partial D2 agonist and a full D1 agonist or monotherapy with a dopamine agonist that has both partial D2 and full D1 agonist properties might be beneficial for treating motor dysfunction in Parkinson's disease without inducing dopaminergic side effects.

[Distribution of alpha 2,3-sialyltransferase mRNA in rat iris and ciliary body]

The distribution of alpha 2,3-sialyltransferase (alpha 2,3-ST) mRNA in the rat iris and ciliary body was investigated with in situ hybridization histochemistry. Strong expression of alpha 2,3-ST mRNA was detected in the inner epithelial layer of the ciliary body and weak expression in the iris epithelium. Since the synthesis of sialoglycoconjugates is completed by terminal sialylation by the action of sialyltransferase (ST), the ST-expressed portions are considered to produce sialoglycoconjugates. Hence, the source of the sialoglycoconjugates found in the inner epithelial layer of the ciliary body in previous histochemical studies is the same epithelial cell.

Midkine is present in the early stage of cerebral infarct

Expression of midkine (MK), a growth factor with neurotrophic activities, was examined immunohistochemically in experimental cerebral infarct of rats. From postoperative day 1 to day 7 after the onset of infarct, anti-MK immunoreactivity was observed in the surrounding ischemic zone of the infarct but not in the necrotic lesion. The immunoreactive material was identified to be MK by Western blotting. On day 14, anti-MK immunoreactivity became negative. Absence of MK in the normal brain was verified both by immunohistochemical staining and Western blotting. The induced expression of MK is an early event: increased expression of glial fibrillary acidic protein (GFAP), a marker of astrocytes, started on day 4 and continued to day 14. These findings suggest that MK is produced around the site of nerve damage and plays a role as a reparative neurotrophic factor during the early phase of cerebral infarct.

[Clinical study on 78 cases of testicular tumor]

Seventy eight patients with testicular tumor were treated in our hospital between 1982 and 1992. Of 78 patients, 74 had germinal cell tumor (seminoma in 47 patients and non-seminoma in 27), and the other 4 had 3 malignant lymphoma and 1 rhabdomyosarcoma. Ages ranged from 1 to 67 years with the average of 36.1. The age of the patients with seminoma was significantly higher than that of patients with non-seminoma. Most patients complained of painless swelling of the scrotal content, but some patients complained of testicular pain, fever, and so on. Those who complained of such symptoms had significantly worse prognosis than those who had only painless scrotal swelling. Patients with non-seminoma visited us about 4.9 months after the onset of their symptoms and 12.1 months in seminoma. Clinical stages were more progressive in non-seminoma than in seminoma. Inguinal orchiectomy was performed followed by irradiation, chemotherapy, retroperitoneal lymph node dissection or thoracotomy. Recurrence developed in 6 patients and the other 7 patients died of progressive disease within 2 years from the first attendance. The 2-year survival rate calculated by the Kaplan-Meier method was 81 and 70% in seminoma and non-seminoma, respectively, and 100, 88, 63, 75, and 22% in stage I, IIA, IIB, IIIO and IIIA, B, C, respectively.

Behavioral involvement of central dopamine D1 and D2 receptors in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned parkinsonian cynomolgus monkeys

To clarify the roles of dopamine D1 and D2 receptors in behavioral symptoms of Parkinson's disease, antiparkinsonian effects of various dopamine agonists in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned parkinsonian monkeys were investigated with regard to induction of hyperactivity such as excitability, irritability and aggressiveness. The non-selective dopamine agonist apomorphine ameliorated the parkinsonism, but induced marked hyperactivity dose-dependently. Pretreatment with either the dopamine D1 antagonist SCH 23390 or the dopamine D2 antagonist sulpiride markedly suppressed the apomorphine-induced hyperactivity with slight attenuation of the antiparkinsonian effects. Both the dopamine D2-receptor agonist quinpirole and the dopamine D1-receptor agonist SKF 82958 ameliorated the parkinsonism in a dose-dependent manner with a slight induction of hyperactivity. Combination treatment of a threshold dose of quinpirole with that of SKF 82958 augmented the antiparkinsonian effects without a marked induction of hyperactivity. However, the combination treatment at higher doses induced marked hyperactivity accompanied by augmented antiparkinsonian effects. These results suggest that stimulation of either central dopamine D1 or D2 receptors is requisite for the antiparkinsonian effects and concurrent strong stimulation of both central dopamine D1 and D2 receptors causes marked hyperactivity which may be predictive of dopaminergic psychiatric side effects.

Lewis X structure increases cell substratum adhesion in L cells

cDNAs of alpha-1,3-fucosyltransferase as well as alpha-1,3/4-fucosyltransferase were placed under the control of a beta-actin promoter and cytomegalovirus enhancer and were introduced into L cells. The transfected cells expressing Le(x) antigen showed increased cell substratum adhesion as compared to the antigen-negative cells, when they were cultured for 2 to 4 h in Dulbecco-modified minimum essential medium containing 0.05% bovine serum albumin. The increased cell substratum adhesion was completely inhibited by cycloheximide and anti-integrin antiserum, and partly by an RGD peptide and EGTA. These findings indicate that Le(x) structure promotes cell adhesion to substratum-bound material secreted by cells, and that the increased adhesion is mediated by integrin. Western blotting experiments have revealed an 85 kDa protein and a 50-60 kDa protein as carriers of Le(x) antigen in transfected cells. The latter is likely to be basigin, which is a member of the immunoglobulin superfamily and is considered to be an integrin-associated protein. We hypothesize that fucosylation of basigin enhances integrin-mediated cell substratum adhesion.

Novel mutation at the initiation codon in the Norrie disease gene in two Japanese families

We have identified a new mutation of Norrie disease (ND) gene in two Japanese males from unrelated families; they showed typical ocular features of ND but no mental retardation or hearing impairment. A mutation was found in both patients at the initiation codon of exon 2 of the ND gene (ATG to GTG), with otherwise normal nucleotide sequences. Their mothers had the normal and mutant types of the gene, which was expected for heterozygotes of the disease. The mutation of the initiation codon would cause the failure of ND gene expression or a defect in translation thereby truncating the amino terminus of ND protein. In view of the rarity and marked heterogeneity of mutations in the ND gene, the present apparently unrelated Japanese families who have lived in the same area for over two centuries presumably share the origin of the mutation.