The effect of calcitonin gene-related peptide on pancreatic blood flow and secretion in conscious dogs

The effects of human alpha-calcitonin gene-related peptide (alpha-CGRP) and beta-CGRP on pancreatic arterial (PA), superior mesenteric (SMA) and left gastric arterial (LGA) blood flows were studied by ultrasound transit-time blood flow meters in five conscious dogs. Intravenous injections of alpha-CGRP and beta-CGRP (5-200 pmol/kg) induced a dose-related increase in PA flow and a dose-related decrease in its resistance. At lower doses, alpha-CGRP was more potent than beta-CGRP, but their maximal responses were similar. The blood flow responses to alpha-CGRP (200 pmol/kg) were 153% of the basal flow in LGA, 313% in PA, and 534% in SMA, while those to VIP (100 pmol/kg) were 467% in LGA, 953% in PA and 163% in SMA. Somatostatin reduced blood flow in all arteries. alpha-CGRP, but not beta-CGRP, at higher doses induced gastric contractions and pancreatic protein-rich secretion, which were blocked by atropine. These results suggest that CGRP in perivascular nerves in the pancreas may regulate pancreatic blood flow in dogs but its physiological function remains to be studied.

Insulinoma with subsequent association of Zollinger-Ellison syndrome

We report a patient with insulinoma associated with Zollinger-Ellison syndrome. A 67-year-old woman was first admitted to our hospital for an abdominal mass. Abdominal computed tomography (CT) revealed a large pancreatic tumor, which was then diagnosed as an unresectable pancreatic adenocarcinoma. At the age of 71, she presented symptoms of hypoglycemia. Fasting blood glucose was 21 mg/dl and plasma immunoreactive insulin level was 846 microU/ ml. Plasma gastrin, glucagon, vasoactive intestinal polypeptide and somatostatin levels were all normal. At the age of 73, hypoglycemic attacks occurred more frequently and she was admitted to our hospital. Abdominal CT scan showed multiple liver metastases. Chemotherapy with 5-fluorouracil and doxorubicin was performed. Three months later, she had an emergency laparotomy because of a perforated duodenal ulcer. Plasma gastrin level was 1,960 pg/ml at that time. Gastric hypersecretion was well controlled with a proton pump inhibitor (lansoprazole) but she died of widespread cancer dissemination 8 years after her first admission. On autopsy, histologic examination revealed a mixed acinar-endocrine carcinoma of the pancreas. Immunohistochemical stains were positive for insulin, gastrin, and alpha1-antitrypsin.

Role of cholecystokinin in the intestinal phase of pancreatic circulation in dogs

The regulatory mechanisms of postprandial pancreatic hyperemia are not well characterized. The aim of this study is to clarify the role of cholecystokinin (CCK) in the intestinal phase of pancreatic circulation. Pancreatic, gastric, and intestinal blood flows were measured by ultrasound transit-time blood flowmeters in five conscious dogs. Pancreatic and gastric secretion and blood pressure were also monitored. Synthetic CCK octapeptide (CCK-8) or gastrin heptadecapeptide (gastrin-17) was infused intravenously, and milk was infused into the duodenum with or without loxiglumide, a specific CCK-A receptor antagonist. CCK-8 induced dose-related increases of pancreatic, but not gastric or intestinal, blood flow and protein secretion without affecting systemic blood pressure. Gastrin-17 did not affect pancreatic blood flow. An intraduodenal infusion of milk increased pancreatic and intestinal blood flows and pancreatic protein secretion. Loxiglumide completely inhibited pancreatic blood flow and protein responses to CCK-8 and milk but not the intestinal blood flow response. CCK is a potent and specific pancreatic vasodilator, with its effect mediated by CCK-A receptors. CCK plays an important role in the regulation of the intestinal phase of the pancreatic circulation in dogs.

Enhancement of oxidative damage to cultured cells and Caenorhabditis elegans by mitochondrial electron transport inhibitors

The mechanisms that lead to mitochondrial damage under oxidative stress conditions were examined in primary and cultured cells as well as in the nematode Caenorhabditis elegans (C. elegans) treated simultaneously with electron transport inhibitors and oxygen gas. Oxygen loading enhanced the damage of PC 12 cells by thenoyltrifluoroacetone (TTFA, a complex II inhibitor), but did not by rotenone (a complex I inhibitor), antimycin (a complex III inhibitor), and sodium azide (a complex IV inhibitor). In primary hepatocytes, the enhancement was observed with the addition of sodium azide and rotenone, but not by TTFA or antimycin. In the nematode, only rotenone and TTFA enhanced the sensitivity under hyperoxia. These results demonstrate that highly specific inhibitors of electron transport can induce oxygen hypersensitivity in cell levels such as PC 12 cells and primary hepatocytes, and animal level of C. elegans. In addition the cell damage is different dependent on cell type and organism.

Final height and growth hormone secretion after bone marrow transplantation in children

Growth hormone (GH) deficiency has been regarded as a principal determinant for growth failure following bone marrow transplantation (BMT). We herein analyzed final height and GH secretion in the patients who received BMT during childhood. The study on final height in 30 patients (23 males; 19 with malignant disease) who underwent BMT before or at the onset of puberty showed the following findings: (1) Final height SD score (SDS) significantly decreased compared to pretreatment height SDS. (2) Patients who underwent BMT before the age of 10 years showed significantly greater reduction in height SDS compared to those who received after the age of 10 years. (3) The type of disease or a difference in preconditioning regimen did not influence the outcome of growth. (4) No patient showed GH deficiency. The study on GH secretion included 71 patients who had been followed for more than 5 years and who underwent insulin tolerance test more than twice following BMT. Thirteen patients experienced poor GH response at least once. Two of these patients had poor GH response repeatedly. In conclusion, children who undergo BMT at younger age have a higher risk of growth failure, and GH deficiency is not a major contributing factor for growth impairment following BMT.

Evidence for association of the myo-inositol monophosphatase 2 (IMPA2) gene with schizophrenia in Japanese samples

In our search for candidate genes for affective disorder on the short arm of chromosome 18, we cloned IMPA2, a previously unreported myo-inositol monophosphatase gene, that maps to 18p11.2. We determined its genomic structure and detected three new single nucleotide polymorphisms (SNPs). In the present study, we screened the gene further to search for additional polymorphisms in Japanese samples and identified seven other SNPs, including a novel missense mutation. These polymorphisms clustered into three regions of the gene. Three relatively informative SNPs, 58G>A, IVS1--15G>A and 800C>T from clusters 1, 2 and 3, respectively, were selected for association tests using a case-control design. The Japanese cohort included 302 schizophrenics, 205 patients with affective disorder and 308 controls. Genotyping was done either by melting curve analysis on the LightCycler or by sequencing. All three SNPs showed significant genotypic association (nominal P = 0.031--0.0001) with schizophrenia, but not with affective disorder. These findings increase the relevance of 18p11.2 to schizophrenia susceptibility because GNAL, which has been shown previously to be implicated in schizophrenia in an independent study, is in close physical proximity to IMPA2. Our findings suggest that IMPA2 or a gene nearby may contribute to the overall genetic risk for schizophrenia among Japanese.

Regulation of neuregulin expression in the injured rat brain and cultured astrocytes

In this report, we investigated whether reactive astrocytes produce neuregulins (glial growth factor 2/heregulin/acetylcholine receptor-inducing activity or neu differentiation factor) and its putative receptors, ErbB2 and ErbB3 tyrosine kinases, in the injured CNS in vivo. Significant immunoreactivities with anti-neuregulin, anti-ErbB2, and anti-ErbB3 antibodies were detected on astrocytes at the injured site 4 d after injury to the adult rat cerebral cortex. To elucidate the mechanisms for the upregulation of neuregulin expression in astrocytes, primary cultured astrocytes were treated with certain reagents, including forskolin, that are known to elevate the intracellular level of cAMP and induce marked morphological changes in astrocytes. Western blot analysis showed that the expression of a 52 kDa membrane-spanning form of a neuregulin protein was enhanced in cultured astrocytes after administration of forskolin. The upregulation of glial fibrillary acidic protein was also observed in astrocytes treated with forskolin. In contrast, inactivation of protein kinase C because of chronic treatment with phorbol ester 12-O-tetradecanoyl phorbol 13-acetate downregulated the expression of the 52 kDa isoform, although other splice variants with apparent molecular sizes of 65 and 60 kDa were upregulated. These results suggest that the enhancement of neuregulin expression at injured sites is induced, at least in part, by elevation in intracellular cAMP levels and/or a protein kinase C signaling pathway. The neuregulin expressed on reactive astrocytes may stimulate their proliferation and support the survival of neurons surrounding cortical brain wounds in vivo.

Urinary excretion of trypsinogen activation peptide (TAP) in taurocholate-induced pancreatitis in rats

Trypsinogen activation peptide (TAP) is a useful marker of severe acute pancreatitis. However, it is sometimes difficult to detect an elevation of plasma TAP in patients with acute pancreatitis because TAP is rapidly cleared from plasma. Therefore, urine TAP has been evaluated to provide an accurate prediction of the outcome of pancreatitis. In the present study, we examined the time course of plasma and urine TAP simultaneously after induction of taurocholate-induced pancreatitis in rats. Plasma TAP levels peaked at 1 hour after the induction of pancreatitis and then gradually decreased, but was still higher than prepancreatitis levels at 48 hours. Significant increases in urine TAP levels were seen at 0-6, 6-12, and 30-36 hours after induction of pancreatitis. The peak level of urine TAP output and TAP/creatinine ratio was observed at 6-12 and 30-36 hours, respectively. Urine TAP concentration showed a significant correlation with both urine TAP/creatinine ratio and TAP output in urine (p < 0.01). In conclusion, plasma TAP increased immediately after the induction of pancreatitis, but excretion of TAP into urine was delayed several hours in taurocholate-induced pancreatitis in rats. The measurement of urine TAP concentration alone sufficiently can reflect the amount of TAP liberated in the pancreas at initial stage of acute pancreatitis.

Polymorphisms in genes involved in neurotransmission in relation to smoking

Smoking behavior is influenced by both genetic and environmental factors. The genetic contribution to smoking behavior is at least as great as its contribution to alcoholism. Much progress has been achieved in genomic research related to cigarette-smoking within recent years. Linkage studies indicate that there are several loci linked to smoking, and candidate genes that are related to neurotransmission have been examined. Possible associated genes include cytochrome P450 subfamily polypeptide 6 (CYP2A6), dopamine D(1), D(2), and D(4) receptors, dopamine transporter, and serotonin transporter genes. There are other important candidate genes but studies evaluating the link with smoking have not been reported. These include genes encoding the dopamine D(3) and D(5) receptors, serotonin receptors, tyrosine hydroxylase, trytophan 2,3-dioxygenase, opioid receptors, and cannabinoid receptors. Since smoking-related factors are extremely complex, studies of diverse populations and of many aspects of smoking behavior including initiation, maintenance, cessation, relapse, and influence of environmental factors are needed to identify smoking-associated genes. We now review genetic polymorphisms reported to be involved in neurotransmission in relation to smoking.

Mutation and association analysis of the Fyn kinase gene with alcoholism and schizophrenia

Lack of Fyn tyrosine kinase increases alcohol sensitivity. Fyn phosphorylates a component of the NMDA receptor, which may be involved in schizophrenia. The Fyn gene is located on human chromosome 6q21, to which linkage of schizophrenia has been suggested. We hypothesized that the Fyn gene is a candidate for predisposition to alcoholism and schizophrenia, and we performed a mutation study of the 5'-flanking region, all coding exons, and exon-intron junctions of the Fyn gene. The SSCP mutation analysis was performed in 48 unrelated alcoholics and 16 unrelated schizophrenics. Three polymorphisms, -93A/G in the 5'-flanking region, IVS10+37T/C in intron 10, and Ex12+894T/G in the 3'-untranslated region, were identified. A rare variant of Ex12+1162TG in the 3'-untranslated region was also detected. Neither missense nor nonsense mutations were found. Case-control studies using a larger sample of unrelated patients and controls did not reveal significant associations between these polymorphisms and alcoholism or schizophrenia. In addition, genotyping a microsatellite marker, D6S302, located in intron 10 of the Fyn gene, did not show a significant association between the marker and alcoholism or schizophrenia. Results of the present study did not provide evidence for the involvement of the genomic Fyn gene mutations in alcoholism or schizophrenia. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:716-720, 2000.

DMSO and glycerol reduce bacterial death induced by expression of truncated N-terminal huntingtin with expanded polyglutamine tracts

Huntington's disease (HD) is caused by CAG repeat expansion in exon 1 of a large gene, IT15, possessing 67 exons. Transgenic mice expressing a truncated N-terminal peptide of huntingtin with an expanded polyglutamine tract translated only from exon 1 develop symptoms similar to Huntington's disease. In the present study, a bacterial system (Escherichia coli) was used to express truncated peptides of huntingtin translated from exon 1 of the HD gene. Bacterial death was observed after the induction of peptides with expanded polyglutamine tracts, and both sodium dodecyl sulfate (SDS)-soluble peptides and insoluble aggregated material were detected by immunoblotting in the homogenates of such E. coli. E. coli death was partially reduced by the addition of dimethylsulfoxide (DMSO) or glycerol to the medium, with a consequent decrease in aggregated material and an increase in SDS-soluble peptide in the homogenate. These results suggest that DMSO and glycerol may decrease the toxicity of huntingtin with expanded polyglutamine tracts by acting as chemical chaperones.

CO2 permeability and bicarbonate transport in microperfused interlobular ducts isolated from guinea-pig pancreas

Permeabilities of the luminal and basolateral membranes of pancreatic duct cells to CO2 and HCO3- were examined in interlobular duct segments isolated from guinea-pig pancreas. Intracellular pH (pHi) was measured by microfluorometry in unstimulated, microperfused ducts loaded with the pH-sensitive fluoroprobe 2'7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF). When HCO3-/CO2 was admitted to the bath, pHi decreased transiently as a result of CO2 diffusion and then increased to a higher value as a result of HCO3- uptake across the basolateral membrane by Na+-HCO3- cotransport. When HCO3-/CO2 was admitted to the lumen, pHi again decreased but no subsequent increase was observed, indicating that the luminal membrane was permeable to CO2 but did not allow HCO3- entry to the cells from the lumen. Only when the luminal HCO3- concentration was raised above 125 mM was HCO3- entry detected. The same was true of duct cells stimulated with forskolin. Recovery of pHi from an acid load, induced by exposure to an NH4+ pulse, was dependent on basolateral but not luminal Na+ and could be blocked by basolateral application of methylisobutylamiloride and H2DIDS. This indicates that the Na+-H+ exchangers and Na+-HCO3- cotransporters are located exclusively at the basolateral membrane. In the presence of HCO3-/CO2, substitution of basolateral Cl- with glucuronate caused larger increases in pHi than substitution of luminal Cl-. This suggests that the anion exchanger activity in the basolateral membrane is greater than that in the luminal membrane. We conclude that the luminal and basolateral membranes are both freely permeable to CO2, but while the basolateral membrane has both uptake and efflux pathways for HCO3-, the luminal membrane presents a significant barrier to the re-entry of secreted HCO3-, largely through the inhibition of the luminal anion exchanger by high luminal HCO3- concentrations.

Time-course magnetic resonance imaging of rat pancreatic cyst after experimental pancreatitis

Fast magnetic resonance (MR) imaging of the rat pancreas was carried out using a snapshot method to observe three-dimensional (3D) and temporal development of the pancreatic cyst after experimental pancreatitis. Acute pancreatitis was induced by a retrograde infusion of the trypsin-taurocholate solution into the pancreatic duct in 23 rats, of which seven survived for one month. Under 2% enflurane anesthesia, (1)H images of the rat abdomen were taken by a 4.7 T magnetic resonance spectrometer under spontaneous breathing. 3D images of the pancreas and cyst were reconstructed from the axial, sagittal and coronal images taken before, 24 h, 7 days, 14 days, 21 days and 28 days after the induction of pancreatitis. The 3D images reconstructed from different slice orientations at each time point showed good agreement with each other. The calculated volumes of the cyst on 7th, 14th, 21st, and 28th day were 0.3 +/- 0.1, 0.8 +/- 0.3, 2.1 +/- 0.6, 6.5 +/- 1.3 mL, respectively. The cystic fluid volume on 28th day was 6.4 +/- 1.4 mL, which confirmed reliability of volume measurement by MR imaging. Fast MR imaging (snapshot) together with 3D reconstruction allows us to understand the detailed chronological and spatial development of pancreatic cyst after acute pancreatitis in rats.

Long-term effects of nafamostat and imipenem on experimental acute pancreatitis in rats

Long-term effects of nafamostat mesylate, a protease inhibitor, and imipenem, an antibiotic, on trypsintaurocholate-induced acute pancreatitis were studied in rats. Sham-operated rats infused with a buffer solution into the pancreatic duct served as controls. Nafamostat (1 mg/kg), imipenem (10 mg/kg), or imipenem + nafamostat in saline was injected subcutaneously 0.25, 3, 24, and 48 hours after the induction of pancreatitis. In untreated rats and control rats, saline was injected at the same intervals as in the treated rats. All rats in an untreated group died within 3.5 days (median survival, 1.25 day) after the induction of pancreatitis. The 2-week survival rate was significantly (p < 0.05) improved by a combination of nafamostat and imipenem (42%), but not by nafamostat (17%), or imipenem (8%) alone. Bacterial culture at 24 hours revealed infection of necrotic pancreatic tissues and ascites by intestinal bacteria in all untreated rats but not in control rats. Bacterial counts were significantly reduced by imipenem, but not by nafamostat. In conclusion, bacterial infection occurred within 24 hours after the induction of trypsintaurocholate pancreatitis in rats. Early treatment with nafamostat + imipenem, but not nafamostat or imipenem alone, improves long-term survival.

Characterization of the human NTAK gene structure and distribution of the isoforms for rat NTAK mRNA

NTAK (neural- and thymus-derived activator for the ErbB kinase, neuregulin-2) is a novel member of the epidermal growth factor (EGF) family. We have isolated and characterized the human NTAK gene, comprising 12 exons spanning in excess of 55 kilobases (kb). The 7. 0kb long mRNA of the human NTAK gene was expressed in the human neuroblastoma SK-N-SH cell line with two alternative isoforms detected. Furthermore, six isoforms have been identified from rat brain and PC-12 cells. Although the alpha isoform of the NTAK gene was found to be expressed in all tissues including brain, the beta isoform was expressed only in rat brain tissues. Potential regulatory regions included consensus binding sites for AP-2, TF-IIIA, Sp-1, and YY-1 located in the 5'-flanking region of the NTAK gene.

Expanded polyglutamine stretches interact with TAFII130, interfering with CREB-dependent transcription

At least eight inherited neurodegenerative diseases are caused by expanded CAG repeats encoding polyglutamine (polyQ) stretches. Although cytotoxicities of expanded polyQ stretches are implicated, the molecular mechanisms of neurodegeneration remain unclear. We found that expanded polyQ stretches preferentially bind to TAFII130, a coactivator involved in cAMP-responsive element binding protein (CREB)-dependent transcriptional activation, and strongly suppress CREB-dependent transcriptional activation. The suppression of CREB-dependent transcription and the cell death induced by polyQ stretches were restored by the co-expression of TAFII130. Our results indicate that interference of transcription by the binding of TAFII130 with expanded polyQ stretches is involved in the pathogenetic mechanisms underlying neurodegeneration.

Serotonin and pancreatic duct function

1. 5-HT inhibits spontaneous fluid secretion as well as stimulated secretion with secretin (cAMP mediated) or ACh (Ca2+ mediated) in the isolated guinea pig pancreatic ducts. 2. The inhibitory effect of 5-HT is reversible and is dependent on the concentration in the range 0.01-0.1 microM, which is much lower than those that affect intestinal motility and secretion. 3. The 5-HT3 receptor in duct cells appears to mediate the inhibitory effect of 5-HT. 4. [Ca2+]i is unlikely to mediate the inhibitory effect of 5-HT.

Bone marrow transplantation for the treatment of X-linked adrenoleukodystrophy

The effects of bone marrow transplantation (BMT) in X-linked childhood adrenoleukodystrophy (ALD) are described in four Japanese patients. Two older patients, 10-year-old boys with IQ 60 and difficulty in school, had favourable results. IQ levels and MRI findings were generally maintained after BMT. One patient showed improvement of gait disturbance. They have both attended ordinary schools after BMT, although a learning disorder persists. On the other hand, two other younger patients with a rapid course and indeterminate IQ at BMT showed deterioration of neurological functions. Indication for BMT seems to be a maintained IQ level, preferably higher than 80, since it seems to be difficult to normalize IQ level after BMT. Younger patients have higher risk of developing a rapidly progressive form of the disease. Identification of presymptomatic boys, and serial and careful follow-up by neuropsychological and neuroradiological studies, are essential prerequisites to successful BMT in X-ALD.

Isolation and characterization of a novel human gene, DRCTNNB1A, the expression of which is down-regulated by beta-catenin

Beta-catenin plays significant roles in cell-to-cell adhesion and the Wnt/Wg signal transduction pathway. Accumulation of this protein in the cytoplasm and nucleus as a result of mutations of the adenomatous polyposis coli tumor suppressor gene or of the beta-catenin gene itself is often seen in a wide variety of tumors including carcinomas of the colon, liver, uterus, and brain. Interaction of accumulated beta-catenin with Tcf/Lef transcription factors is known to deregulate expression of some downstream genes, but the precise mechanisms whereby beta-catenin contributes to carcinogenesis remain to be disclosed. Here we report isolation of a novel murine gene, Drctnnb1a (down-regulated by Ctnnb1, a), the expression of which was experimentally down-regulated in response to the activated form of beta-catenin. To investigate a possible role of DRCTNNB1A in cancers, we also isolated the human homologue, DRCTNNB1A, the deduced product of which was 91% identical to the murine protein. The transcript was expressed in all human tissues examined, and we assigned the genomic location of DRCTNNB1A to chromosomal band 7p15.3 by in situ hybridization. Expression of DRCTNNB1A in SW480 colon cancer cells was significantly increased in response to reduction of intracellular beta-catenin by adenovirus-mediated transfer of the beta-catenin-binding domain of the adenomatous polyposis coli gene into the cells. Furthermore, we documented reduced expression of DRCTNNB1A in 12 of 15 primary colorectal cancers examined, compared with corresponding adjacent noncancerous mucosae. Our results implied that DRCTNNB1A is one of the genes involved in the beta-catenin-Tcf/Lef signaling pathway, and that reduced expression of DRCTNNB1A may have some role in colorectal carcinogenesis.

Mutation and association analysis of the 5' region of the dopamine D3 receptor gene in schizophrenia patients: identification of the Ala38Thr polymorphism and suggested association between DRD3 haplotypes and schizophrenia

Although the association between the Ser9Gly polymorphism of the dopamine D3 receptor gene (DRD3) and schizophrenia has been investigated by many research groups, it is not known whether the Ser9Gly polymorphism alone or a variation in linkage disequilibrium may effect susceptibility to schizophrenia. We searched the 5' region of the DRD3 gene and found three novel polymorphisms: -712G/C, -205A/G, and Ala38Thr. The Ala38Thr polymorphism is located in the first transmembrane region and is conserved in the monkey, mouse, and rat. Case-control comparisons in 153 Japanese schizophrenia patients and 122 Japanese controls did not suggest an association between Ala38Thr and schizophrenia. However, there was a marginally significant association between the Ser9 allele of the Ser9Gly polymorphisms and schizophrenia (P = 0.02). Furthermore, there was a highly significant association between haplotypes of the -712G/C, -205A/G, and Ser9Gly polymorphisms and schizophrenia (P = 0.0007, corrected P = 0.007). These positive findings were replicated in an additional 99 Japanese schizophrenia patients and 132 controls (P = 0.04 and 0.0004, respectively). The most allelic differences of the Ser9Gly polymorphism between patient and control groups arose from the chromosome carrying specific alleles of the other three polymorphisms. This study indicates unknown variant(s) in linkage disequilibrium with the DRD3 haplotypes associated with schizophrenia.

Isolation and characterization of human NBL4, a gene involved in the beta-catenin/tcf signaling pathway

beta-Catenin, a key regulator of cellular proliferation, is often mutated in various types of human cancer. To investigate cellular responses related to the beta-catenin signaling pathway, we applied a differential display method using mouse cells transfected with an activated form of mutant beta-catenin. This analysis and subsequent northern-blot hybridization confirmed that expression of a murine gene encoding NBL4 (novel band 4.1-like protein 4) was up-regulated by activation of beta-catenin. To examine a possible role of NBL4 in cancer, we isolated the human homologue of the murine NBL4 gene by matching mNBL4 against the human EST (expressed sequence tag) database followed by 5' rapid amplification of cDNA ends (5'RACE). The cDNA of hNBL4 encoded a protein of 598 amino acids that shared 87% identity in amino acid sequence with murine NBL4 and 71% with zebrafish NBL4. A 2.2-kb hNBL4 transcript was expressed in all human tissues examined with high levels of expression in brain, liver, thymus and peripheral blood leukocytes and low levels of expression in heart, kidney, testis and colon. We determined its chromosomal localization at 5q22 by fluorescence in situ hybridization. Expression of hNBL4 was significantly reduced when beta-catenin was depleted in SW480 cells, a human cancer cell line that constitutionally accumulates beta-catenin. The results support the view that NBL4 is an important component of the beta-catenin / Tcf pathway and is probably related to determination of cell polarity or proliferation.

Pontine atrophy in spinocerebellar ataxia type 6

To investigate the clinical range of spinocerebellar ataxia type 6 (SCA6), we screened CAG repeat expansion in the voltage-dependent alpha 1A calcium channel gene (CACNL1A4) in 71 ataxic patients in 60 families; 54 patients in 43 families with hereditary ataxia and 17 sporadic patients. Thirteen patients with SCA6 were detected to have elongated CAG in CACNL1A4. Of these, 7 patients had been diagnosed as having hereditary cerebellar cortical atrophy, and 6 patients had been found to have sporadic occurrence. One patient showed distinct pontine atrophy with prominent horizontal or oblique gaze nystagmus which is an unusual feature in sporadic olivopontocerebellar atrophy. For the efficient screening of SCA6, we would propose testing CAG repeat expansion in CACNL1A4, in patients with one of two markers: (1) horizontal or oblique gaze nystagmus without other eye movement disorders, (2) pure cerebellar atrophy, even if occurrence is sporadic. We should note that the pontine atrophy could also be caused by CAG repeat expansion in CACNL1A4.