Purification and characterization of UDP-N-acetylglucosamine: alpha1,3-D-mannoside beta1,4-N-acetylglucosaminyltransferase (N-acetylglucosaminyltransferase-IV) from bovine small intestine

A new beta1,4-N-acetylglucosaminyltransferase (GnT) which involves in branch formation of Asn-linked complex-type sugar chains has been purified 224,000-fold from bovine small intestine. This enzyme requires divalent cations, such as Mn2+, and catalyzes the transfer of GlcNAc from UDP-GlcNAc to biantennary oligosaccharide and produces triantennary oligosaccharide with the beta1-4-linked GlcNAc residue on the Manalpha1-3 arm. The purified enzyme shows a single band of Mr 58,000 and behaves as a monomer. The substrate specificity demonstrated that the beta1-2-linked GlcNAc residue on the Manalpha1-3 arm (GnT-I product) is essential for the enzyme activity. beta1-4-Galactosylaion to this essential beta1-2-linked GlcNAc residue or N-acetylglucosaminylation to the beta-linked Man residue (bisecting GlcNAc, GnT-III product) blocks the enzyme action, while beta1-6-N-acetylglucosaminylation to the Manalpha1-6 arm (GnT-V product) increases the transfer. Based on these findings, we conclude that the purified enzyme is UDP-N-acetylglucosamine:alpha-3-D-mannoside beta-1,4-N-acetylglucosaminyltransferase IV (GnT-IV), that has been a missing link on biosynthesis of complex-type sugar chains.

Human transferrin (Tf): a single mutation at codon 570 determines Tf C1 or Tf C2 variant

Transferrin (Tf) has many variants, as revealed by isoelectric focusing (IEF). Although these Tf variants have long been thought to arise from the multiple alleles at single Tf locus, amino acid substitution related to the two major variants, Tf C1 and Tf C2, has so far not been reported. We investigated the difference responsible for Tf C1 and Tf C2 variants and identified a single base change in exon 15 of the Tf gene resulting in the phenotypes on IEF. C/T base substitution at codon 570 replaced Pro in Tf C1 with Ser in Tf C2. Based on this nucleotide substitution, we established PCR-based genotyping for the Tf C1 and Tf 2 alleles.

N-glycosylation is requisite for the enzyme activity and Golgi retention of N-acetylglucosaminyltransferase III

UDP-N-acetylglucosamine: beta-D-mannoside beta-1,4N-acetylglucosaminyltransferase III (GnT-III, EC 2.4.1.144) is a glycoprotein involved in the biosynthesis of N-linked oligosaccharides. Rat GnT-III contains three potential N-glycosylation sites, which have been predicted to be Asn243, Asn261, and Asn399. To study the roles of N-glycosylation in the GnT-III function, rat GnT-III was expressed in COS-1 cells under tunicamycin or castanospermine treatment. The tunicamycin-treated GnT-III, which was not N-glycosylated, had almost no activity. The castanospermine-treated GnT-III was not localized in the Golgi, but glucosylation did not affect its activity. To clarify the role of individual N-glycosylations, we obtained a series of mutant cDNAs in which some or all of the potential glycosylation sites were eliminated by site-directed mutagenesis, and expressed them in COS-1 cells. All the mutants exhibited lower enzyme activity than the wild-type, but deglycosylation at individual sites had different effects on the enzyme activity. The deglycosylation at Asn243 or Asn261 was more effective on the activity than that at Asn399. The enzyme activity decreased as the number of glycosylation sites decreased. The null glycosylation mutant had no activity, corresponding to the case of tunicamycin-treated wild-type GnT-III. Kinetic analysis revealed that the deglycosylation at Asn243 or Asn261 resulted in slightly lower affinity for the donor substrate, but the other mutation did not significantly change the K(m) value for either the donor or acceptor. None of the mutant GnT-IIIs showed perinuclear localization or Golgi retention, that was observed for the wild-type protein. This is the first demonstration that the glycosyltransferase localized in the Golgi apparatus requires N-glycosylation for its activity and retention.

Somatodendritic localization of phosphorylated tau in neonatal and adult rat cerebral cortex

We studied the distribution of phosphorylated tau (p-tau) in neonatal and adult rat cerebrum using monoclonal antibodies that recognize distinct tau epitopes in a phosphorylation-dependent manner. In neonatal cortex, p-tau was detected in the apical dendrites and somata of pyramidal neurons as well as in axons. In adults, p-tau was present predominantly in neuronal somata and dendrites and, to a lesser extent, in axons, whereas tau-1, that recognizes a dephosphorylated tau epitope, immunolabeled neuropil and axons, and not the neuronal somata and dendrites. These results suggest that tau phosphorylated at multiple sites is present in somatodendritic compartments of rat cortical neurons throughout life, and that phosphorylation may be one of the determinants for the compartmentalization of tau in the brain.

Free radicals in the cerebrospinal fluid are associated with neurological disorders including mitochondrial encephalomyopathy

The free radical levels in the cerebrospinal fluid of 8 patients with neurological diseases and 9 undergoing lumbar anesthesia for surgery were measured. The ascorbate free radical level 10 min after lumbar puncture showed a positive correlation with the hydroxyl radical level. In the patient with mitochondrial encephalomyopathy, the levels of hydroxyl and ascorbate free radicals increased upon discontinuation of treatment and decreased upon its resumption, and the ascorbate free radical levels without therapy fell after lumbar puncture. The free radical levels in the cerebrospinal fluid may reflect the degree of oxidative stress in the central nervous system.

Amyloid beta-protein (A beta) accumulation in the leptomeninges during aging and in Alzheimer disease

The results of well-characterized two-site enzyme immunoassays showed that the crude leptomeninges (consisting of the pia matter, arachnoid matter, and leptomeningeal vessels [LV]) from aged control brains and brains affected by Alzheimer disease (AD) contain very high levels of amyloid beta-protein (A beta). To learn about the source of A beta, we carefully dissected out both leptomeninges (LM) and LV under a dissecting microscope and determined the levels of soluble A beta in each. The purity of these dissected tissues was confirmed by the absence or presence of alpha-smooth muscle actin representing LV by Western blotting. Surprisingly, the amounts of A beta in each dissected sample were nearly equivalent on a weight basis. In each compartment from aged controls the level of A beta 1-42 was comparable to that of A beta 1-40, while in AD brain A beta 1-40 was a predominant species in both LM and LV. In some cases careful immunocytochemical examination revealed the presence of A beta deposits that were immunolabeled by several A beta monoclonal antibodies in leptomeningeal layers (most often in the arachnoid matter). The extent of A beta deposition in LM appeared to be much less than that explained by the soluble A beta levels, suggesting that immunocytochemically undetectable A beta can accumulate in LM. These observations indicate that leptomeninges are a large reservoir of A beta in normal aged individuals and in AD patients.

Specific increase in amyloid beta-protein 42 secretion ratio by calpain inhibition

Cerebral deposition of amyloid beta-protein (Abeta) as senile plaques is a pathological hallmark of Alzheimer's disease (AD). Abeta falls into two major subspecies defined by their C-termini, Abeta40 and Abeta42, ending in Val-40 and Ala-42, respectively. Although Abeta42 accounts for only approximately 10% of secreted Abeta, Abeta42 is the predominant species accumulated in senile plaques in AD brain and appears to be the initially deposited species. Its secretion level has recently been reported to be increased in the plasma or culture media of fibroblasts from patients affected by any of early-onset familial AD (FAD). Thus, inhibition of Abeta42 production would be one of the therapeutic targets for AD. However, there is little information about the cleavage mechanism via which Abeta40 and Abeta42 are generated and its relationship to intracellular protease activity. Here, we examined by well-characterized enzyme immunoassay the effects of calpain and proteasome inhibitors on the levels of Abeta40 and Abeta42 secretion by cultured cells. A calpastatin peptide homologous to the inhibitory domain of calpastatin, an endogenous calpain specific inhibitor, induced a specific increase in secreted Abeta42 relative to the total secreted Abeta level, a characteristic of the cultured cells transfected with FAD-linked mutated genes, while a proteasome specific inhibitor, lactacystin, showed no such effect. These findings suggest that the Abeta42 secretion ratio is modulated by the calpain-calpastatin system and may point to the possibility of exploring particular compounds that inhibit Abeta42 secretion through this pathway.

Mucinous cystadenoma of the appendix with raised serum carcinoembryonic antigen concentration: clinical and pathological features

A case of mucinous cystadenoma mimicking ovarian cancer is reported. Serum carcinoembryonic antigen (CEA) concentration was raised, and computed tomography of the abdomen and pelvis demonstrated a long oval shaped cystic mass measuring 9 cm in length on the right anterior side of the uterus. Because of possible right ovarian cancer, laparotomy was performed and the mass was found to be a mucinous cystadenoma of the appendix. This case indicates that mucinous cystadenoma of the appendix may show an unusual presentation including its location as well as the high serum CEA, mimicking ovarian cancer. Therefore, gynaecologists as well as gastroenterologists should consider its possibility as a differential diagnosis of the right adnexal mass in a patient without previous appendectomy.

Intracellular generation and accumulation of amyloid beta-peptide terminating at amino acid 42

Amyloid beta-peptide (Abeta) is known to accumulate in senile plaques of Alzheimer's disease (AD) patients and is now widely believed to play a major role in the disease. Two populations of peptides occur terminating either at amino acid 40 or at amino acid 42 (Abeta1-40 and Abeta1-42). Alternative N-terminal cleavages produce additional heterogeneity (Abetax-40 and Abetax-42). Peptides terminating at amino acid 42 are believed to be the major player in sporadic AD as well as familial AD (FAD). Whereas the cellular mechanism for the generation of Abeta terminating at amino acid 40 is well understood, very little is known about the cleavage of Abeta after amino acid 42. By using two independent methods we demonstrate intracellular Abeta1-42 as well as Abetax-42 but less Abetax-40 and Abeta1-40 in kidney 293 cells stably transfected with wild type beta-amyloid precursor protein (betaAPP) or the FAD-associated Val/Gly mutation. Moreover, retention of betaAPP within the endoplasmic reticulum (ER) by treatment with brefeldin A does not block the cleavage at amino acid 42 but results in an increased production of all species of Abeta terminating at amino acid 42. This indicates that the cleavage after amino acid 42 can occur within the ER. Treatment of cells with monensin, which blocks transport of (betaAPP) within the Golgi causes a marked accumulation of intracellular Abetax-42 and Abetax-40. Therefore these experiments indicate that the gamma-secretase cleavage of Abeta after amino acid 42 can occur within the ER and later within the secretory pathway within the Golgi. Moreover inhibition of reinternalization by cytoplasmic deletions of betaAPP as well as inhibition of intracellular acidification by NH4Cl does not block intracellular Abeta1-42 or Abetax-42 production.

Significant downregulation of the major swine xenoantigen by N-acetylglucosaminyltransferase III gene transfection

Introduction of the beta-D-mannoside beta-1,4-N-acetylglucosaminyltransferase III (GnT-III) gene into swine endothelial cells (SEC) reduced their susceptibility to normal human serum (NHS) in complement-mediated cell lysis and also suppressed the antigenicity to human natural antibodies as evidenced by flow cytometric analysis, as well as Griffonia simplicifolia 1 isolectin (1B4 lectin) binding to the Gal alpha1-3 Gal beta 1-4 GlcNAc-R (the alpha-galactosyl epitope). Western blot analysis indicated that proteins smaller than 66 kDa had diminished reactivity to NHS and 1B4 lectin. GnT-III, a key enzyme involved in branch formation of N-linked sugars, was found to downregulate the expression of xenoantigen, suggesting that this approach may be of value in clinical xenotransplantation in the future.

Gastric inhibitory polypeptide activates MAP kinase through the wortmannin-sensitive and -insensitive pathways

The signal transduction pathways of a cloned human gastric inhibitory polypeptide (GIP) receptor have been investigated in CHO cells stably expressing this receptor. Exposure of GIP receptor expressing cells to GIP significantly increased MAP kinase activity. Time course analysis showed that a rapid and marked increase in MAP kinase activation was detected and that this activation reached maximal levels 10 min after the addition of GIP. Dose-response analysis showed that GIP activated MAP kinase activity in a dose-dependent manner with an ED50 value of 5.9 x 10(-10) M of GIP. Wortmannin, a potent inhibitor of phosphatidylinositol 3-kinase (PI3-kinase), partially inhibited GIP-induced MAP kinase activation, suggesting that GIP activates MAP kinase through two different, wortmannin-sensitive and -insensitive pathways. It has been demonstrated that in CHO cells cAMP attenuates MAP kinase activity by inhibiting Raf-1. Since GIP elevates intracellular cAMP, we examined the effects of cAMP on MAP kinase activation. Interestingly, forskolin, which increased intracellular cAMP levels, significantly inhibited MAP kinase activation by GIP, but did not affect MAP kinase activation by GIP in the presence of wortmannin, suggesting that the wortmannin-sensitive pathway activates an MAP kinase cascade at or above the level of Raf-1 and that the wortmannin-insensitive pathway activates an MAP kinase cascade below the level of Raf-1. These findings demonstrate that the GIP receptor is linked to the MAP kinase cascade via at least two different pathways.

Overexpression of N-acetylglucosaminyltransferase III disrupts the tyrosine phosphorylation of Trk with resultant signaling dysfunction in PC12 cells treated with nerve growth factor

beta-1,4-N-Acetylglucosaminyltransferase III (GnT-III: EC 2.4.1.144) is a pivotal glycosyltransferase which participates in branch formation by catalysis of the synthesis of a bisecting GlcNAc structure in N-glycans. These structures are thought to be one of the unique features of the N-glycans of neural tissues. To examine the intracellullar role of GnT-III expression and its product in neural cells, its gene was overexpressed in rat pheochromocytoma PC12 cells which normally express a low level of GnT-III. In the GnT-III gene-transfected cells, lectin blot analysis showed that some glycoproteins showed increased levels of bisecting GlcNAc structures. Following treatment with nerve growth factor (NGF) the control cells showed neurite outgrowth for differentiation whereas the transfectants showed no morphological response or change in the rate of cell growth. Transient tyrosine phosphorylation of the Trk/NGF receptor was detected at 5-15 min after NGF treatment in control cells, but not detected in the GnT-III gene-transfected cells despite the intact binding of NGF to the cells. Moreover the dimerization of Trk with NGF treatment was not induced in the GnT-III transfectant as compared with the dimerization seen in control cells. These results indicate that overexpression of GnT-III gene in PC12 cells affects some functions of glycoprotein receptors such as Trk by alteration of N-glycan structures, and results in changes in the intracellular signaling pathway of tyrosine phosphorylation modified by NGF.

Purification and cDNA cloning of GDP-L-Fuc:N-acetyl-beta-D-glucosaminide:alpha1-6 fucosyltransferase (alpha1-6 FucT) from human gastric cancer MKN45 cells

GDP-L-Fuc:N-acetyl-beta-D-glucosaminide:alpha1-6 fucosyltransferase (alpha1-6 FucT), which catalyzes the transfer of fucose from GDP-Fuc to N-linked type complex glycopeptides, was purified from a culture supernatant of human gastric cancer cell line MKN45. The purification procedures included chromatographies on Q-Sepharose Fast Flow, synthetic GDP-hexanolamine-Sepharose, and GnGn-bi-Asn-Sepharose columns. SDS-PAGE of the purified enzyme gave a major band corresponding to an apparent molecular mass of 60 kDa. The enzyme was recovered in a 12% final yield with an approximately 4,600-fold increase in specific activity. The pH optimum was 7.5, and the enzyme was fully active in the presence of 5 mM EDTA and did not require divalent cations, Mg2+ and Ca2+. Oligonucleotide primers designed from partial amino acid sequences were used to amplify and clone alpha1-6 FucT cDNA from a cDNA library of MKN45 cells. The cDNA encodes 575 amino acids in length, and contains the predicted N-terminal and internal amino acid sequences derived on lysyl endopeptidase digestion. The homology to porcine brain alpha1-6 FucT is 92.2% at the nucleotide level and 95.7% at the amino acid level. No putative N-glycosylation sites were found in the predicted amino acid sequence of the human MKN45 cell enzyme or that of porcine brain. Thus, the enzyme is distinct from other fucosyltransferases which catalyze alpha1-2, alpha1-3, and alpha1-4 fucose addition.

[Application of tuberculosis medical examination radiographs to scoliosis screening in high schools]

The purpose of this study was to assess the utilization of tuberculosis examination radiographs for scoliosis screening in high schools, for early diagnosis and early treatment of adolescent idiopathic scoliosis in the health management of students. We examined 2,068 first year high school students (1,058 males and 1,010 females) in Wakayama Prefecture, who had chest X-ray photographs taken between 1994 to 1996, and 24 cases (3 males and 21 females) were identified with scoliosis of more than 10 degrees Cobb angle. Fifteen of the cases received further examinations in the hospital, and were diagnosed with definite adolescent idiopathic scoliosis, while 6 cases who did not receive hospital examinations had their abnormality of the spine noted in past periodic health examinations. In the remaining 3 students scoliosis could not be confirmed. The correlation coefficient between the Cobb angle measured in the tuberculosis examination radiographs and in the total spinal radiographs taken by the hospital was 0.815 (p < 0.001). These results suggest that the tuberculosis examination radiographs may be useful for scoliosis screening in high schools.

Bisecting GlcNAc structures act as negative sorting signals for cell surface glycoproteins in forskolin-treated rat hepatoma cells

The bisecting N-acetylglucosamine residue is formed by UDP-N-acetylglucosamine:beta-D-mannoside-beta-1, 4-N-acetylglucosaminyltransferase III (GnT-III), a key branching enzyme for N-glycans. We found that forskolin, an adenylyl cyclase activator, markedly enhanced GnT-III at the transcriptional level in various hepatoma cells and hepatocytes, resulting in an increase of bisecting GlcNAc residues in various glycoproteins, as judged from the lectin binding to erythroagglutinating phytohemagglutinin (E-PHA). In whole cell lysates, the E-PHA binding was increased, and leukoagglutinating phytohemagglutinin (L-PHA) binding was decreased at 12 h after forskolin treatment, by time, both GnT-III activity and mRNA had reached the maximum levels. In contrast, the binding capacity as to E-PHA, determined by fluorescence-activated cell sorting on the cell surface, was decreased, suggesting that bisecting GlcNAc structures in certain glycoproteins changed the expression levels of glycoproteins and decreased their sorting on the cell surface. Fractionated organelles of M31 cells showed that the binding capacity as to E-PHA was mainly localized in Golgi membranes and lysosomes. This was also supported by a fluorescence microscopy. In order to determine whether or not the bisecting GlcNAc residue acts as a sorting signal for glycoproteins, N-oligosaccharide structures of lysosomal-associated membrane glycoprotein 1 and beta-glucuronidase, gamma-glutamyltranspeptidase, and secretory glycoproteins such as ceruloplasmin and alpha-fetoprotein were measured by E-PHA and L-PHA blotting after immunoprecipitation. The expression levels of lysosomal membrane glycoprotein 1 and gamma-glutamyltranspeptidase on the cell surface were decreased at 12 h after forskolin treatment, indicating that the bisecting GlcNAc structure may act as a negative sorting signal for the cell surface glycoproteins and may alter the characteristics of hepatoma cells. This is the first report on glycoprotein sorting related to a specific structure of oligosaccharides, bisecting GlcNAc.

Telomere shortening in peripheral blood cells was related with aging but not with white blood cell count

Telomeres in somatic cells are progressively shortened with aging. We investigated the relationship between the telomere length and other factors which may affect the frequency of cell divisions, in peripheral blood cells. Shortening of telomeric repeats was correlated with aging (p < 0.0001), but not with white blood cell count, neutrophil count, and smoking habit. Not only the number of cell divisions, but also some other factors, such as upregulation level of telomerase activity concomitant with the cell division in hematopoietic progenitor cells, might affect the length of telomeric repeats in blood cells.

Identification of two missense mutations in the GIP receptor gene: a functional study and association analysis with NIDDM: no evidence of association with Japanese NIDDM subjects

Gastric inhibitory polypeptide (GIP) potently stimulates insulin secretion from pancreatic islets in the presence of glucose as an incretin. Because the insulinotropic effect of GIP is reduced in NIDDM, it should be clarified whether defects in the GIP receptor gene contribute to the impaired insulin secretion in NIDDM. Using genomic DNA samples from Japanese NIDDM and non-NIDDM subjects, we have investigated the entire coding region of the GIP receptor gene by polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP). We have identified two missense mutations, Gly198-->Cys (Gly198Cys) in exon 7 and Glu354-->Gln (Glu354Gln) in exon 12. Investigation of the function of GIP receptor with either of these mutations reveals a half-maximal stimulation value of GIP-induced cAMP response in Chinese hamster ovary cells expressing the GIP receptor with Gly198Cys of 6.3 +/- 1.2 x 10(-10) mol/l (n = 3), which was considerably higher than that of the normal GIP receptor, 9.4 +/- 3.8 x 10(-12) mol/l GIP (n = 3), whereas that of the GIP receptor with Glu354Gln was not significantly different from that of the normal GIP receptor. To assess the possible role of the GIP receptor gene in genetic susceptibility to NIDDM, we have examined the allelic frequencies of Gly198Cys and Glu354Gln in NIDDM and control subjects. Association studies show no relationship between NIDDM and either of the two mutations.

Purification and cDNA cloning of porcine brain GDP-L-Fuc:N-acetyl-beta-D-glucosaminide alpha1-->6fucosyltransferase

GDP-L-Fuc:N-acetyl-beta-D-glucosaminide alpha1-->6fucosyltransferase (alpha1-6FucT; EC 2.4.1.68), which catalyzes the transfer of fucose from GDP-Fuc to N-linked type complex glycopeptides, was purified from a Triton X-100 extract of porcine brain microsomes. The purification procedures included sequential affinity chromatographies on GlcNAcbeta1-2Manalpha1-6(GlcNAcbeta1-2Manalpha1- 2)Manbeta1-4GlcNAcbet a1-4GlcNAc-Asn-Sepharose 4B and synthetic GDP-hexanolamine-Sepharose 4B columns. The enzyme was recovered in a 12% final yield with a 440, 000-fold increase in specific activity. SDS-polyacrylamide gel electrophoresis of the purified enzyme gave a major band corresponding to an apparent molecular mass of 58 kDa. The alpha1-6FucT has 575 amino acids and no putative N-glycosylation sites. The cDNA was cloned in to pSVK3 and was then transiently transfected into COS-1 cells. alpha1-6FucT activity was found to be high in the transfected cells, as compared with non- or mock-transfected cells. Northern blotting analyses of rat adult tissues showed that alpha1-6FucT was highly expressed in brain. No sequence homology was found with other previously cloned fucosyltransferases, but the enzyme appears to be a type II transmembrane protein like the other glycosyltransferases.

Proliferating cell nuclear antigen (PCNA) expressed in human leptomeninges

Here we report on the presence of proliferating cell nuclear antigen (PCNA) in human leptomeninges from 35 normal subjects with ages ranging from 57 to 94 years. Strong immunoreactivity with PC10 (a monoclonal antibody to PCNA) was detected in the nuclei of meningothelial cells, smooth muscle cells of leptomeningeal vessels, and ependymal cells. An immunoblot of leptomeningeal homogenate with PC10 showed the presence of a single band at 35 KD, the expected molecular mass of PCNA. Ki-67, another marker for cell proliferation, was undetectable in human leptomeninges. These observations point to isolated PCNA expression in tissue in which cells are not actively proliferating.

Transcriptional regulation of the N-acetylglucosaminyltransferase V gene in human bile duct carcinoma cells (HuCC-T1) is mediated by Ets-1

N-Acetylglucosaminyltransferase V (GnT-V) catalyzes the transfer of N-acetylglucosamine from UDP-N-acetylglucosamine to alpha-6-D-mannoside to produce the beta1-6 linked branching of N-glycan oligosaccharides, which controls the polylactosamine content. The expression of N-acetylglucosaminyltransferase V, which contains 17 exons and spans 155 kilobase pairs, is expressed in a tissue- and cell type-specific manner and is regulated at the level of transcription by multiple promoters (Saito, H., Gu, J., Nishikawa, A., Ihara, Y., Fujii, J., Kohgo, Y., and Taniguchi, N. (1995) Eur. J. Biochem. 233, 18-26). To elucidate the mechanism by which the GnT-V gene is expressed in a cell- and tissue-specific manner, cell-restricted expression was analyzed using the 5'-upstream regions of the human GnT-V gene spanning base pairs -2760 to +23 in a human bile duct carcinoma cell line, HuCC-T1. We characterized two cis-acting elements that are potentially important in HuCC-T1 cell-specific expression. The two elements each contain an Ets-1 binding site, 5'-GGA-3'. Specific binding of Ets-1 to the respective elements was demonstrated by competition analysis as well as by antibody supershift experiments. Cotransfection of an Ets-1 expression plasmid along with a GnT-V promoter-luciferase reporter plasmid revealed the participation of Ets-1 in the regulation of the GnT-V gene transcription. These data indicated that the transcriptional regulation of the GnT-V gene was mediated by transcription factor Ets-1.

Tau is widely expressed in rat tissues

The microtubule-associated protein tau, a major component of paired helical filaments in Alzheimer's disease, had been thought to be a neuron-specific protein. We investigated various rat tissues using both reverse transcriptase-coupled polymerase chain reaction and immunoblotting. tau was found to be widely expressed in many tissues besides the nervous system: at relatively high levels in the heart, skeletal muscle, lung, kidney, and testis and at low levels in the adrenal gland, stomach, and liver. In terms of the tau isoform expression, tissues fall into three classes: those expressing predominantly small tau, those expressing predominantly big tau, and those expressing both at comparable levels. The phosphorylation state of tau varied among the tissues, as shown by differences in the extents of changes in the reactivities with Tau 1 and electrophoretic mobilities after dephosphorylation. It is notable that tau in many nonneural tissues was highly phosphorylated at Ser396 (according to the numbering of the 441-residue human tau isoform). Thus, tau is widely expressed in rat tissues.