Expression of presenilin-1 and -2 mRNAs in rat and Alzheimer's disease brains

Recently, new genetic linkages have been identified for early-onset familial Alzheimer's disease (AD). Mutations have been found in the presenilin (PS)-1 (S182) gene on chromosome 14 and the PS-2 (STM2/E5-a) gene on chromosome 1. We have investigated the distribution of gene expression of both presenilins in normal rat brain, and in human control and AD cases using in situ hybridization histochemistry. In normal rat brain, intense PS-1 mRNA expression was observed predominantly in neurons, particularly hippocampal pyramidal and dentate granular neurons and cerebellar Purkinje and granular neurons. The distribution of intensely expressing PS-2 mRNA cells was similar to that of PS-1, but additional groups in the brain stem and cortex were identified. Faint but significant mRNA expression of both PS genes was detected in white matter. In control human cases, the same neuronal cell types as seen in rat brain expressed both PS mRNAs in the hippocampus and cerebellum. In AD cases, the expression of both mRNAs was markedly decreased in the hippocampus but not in the cerebellum. In addition, PS-2 hybridization showed increased mRNA expression in astrocyte-like cells in affected areas of AD cases. The present data indicate that the PS genes may play important roles in specific neurons in normal brain, and that the decreased expression in neurons in sporadic AD brain may bear some relationship to the pathogenesis.

A detailed analysis of the role of K-ras gene mutation in the progression of colorectal adenoma

To elucidate the role of ras gene mutations during the early stage of colorectal tumour progression, K-ras gene mutations were analysed in 32 benign adenomas and 36 adenomas with focal carcinoma in the colorectum by microscraping of histologically pure regions from tissue sections, polymerase chain reaction-restriction fragment length polymorphism and in part by direct sequencing. Several regions were scraped out and analysed when an adenoma contained areas with different grades of dysplasia. The frequencies of K-ras gene mutation in mild dysplasia, moderate dysplasia and focal carcinoma were 19% (7/36), 51% (25/49) and 39% (14/36) respectively. The K-ras gene status was heterogeneous in 4 of the 11 benign adenomas from which multiple samples were obtained, and mutations were always found in the regions with more advanced dysplasia in these adenomas. Thirteen of the 36 adenomas with focal carcinoma showed heterogeneity of mutations between the adenoma region and the focal carcinoma. Seven of which had mutations only in the adenoma region. These findings indicated that the K-ras gene mutations occur during the late stage of adenoma progression and may confer a more advanced morphological phenotype of adenoma, but these mutations are not mainly involved in malignant transformation from adenoma to carcinoma.

MDM2 gene amplification and expression in non-small-cell lung cancer: immunohistochemical expression of its protein is a favourable prognostic marker in patients without p53 protein accumulation

MDM2 is an oncoprotein that inhibits p53 tumour-suppressor protein. Amplification of the MDM2 gene and overexpression of its protein have been observed in some human malignancies, and these abnormalities have a role in tumorigenesis through inactivation of p53 function. To determine the clinicopathological and prognostic value of MDM2 abnormalities in non-small-cell lung cancer (NSCLC), MDM2 gene amplification and its protein expression status were analysed in surgically resected materials. MDM2 gene amplification was detected in only 2 (7%) of the 30 tested patients. MDM2 protein was found immunohistochemically in a total of 48 (24%) of the 201 patients. MDM2 protein was slightly frequently observed in patients with adenocarcinoma, but its presence or absence was not associated with clinicopathological factors such as T-factor, N-factor, stage, tumour size, differentiation or p53 protein status. Overall, MDM2-positive patients tended to have a better prognosis (P = 0.062). In particular, among immunohistochemically p53-negative patients (n = 110), those with positive MDM2 protein expression showed significantly better prognosis (P = 0.039) and, in a multivariate analysis, MDM2 protein status was a favourable prognostic factor (P = 0.037). In contrast, among p53-positive patients (n = 91), there was no difference in prognosis depending on MDM2 protein status. Thus, in the NSCLC patients studied, MDM2 gene amplification was a minor event, but expression of its protein, which was often observed immunohistochemically, was a favourable prognostic marker, especially among patients without p53 protein accumulation. Further study is needed to determine how MDM2 protein expression results in a better prognosis.

Determination of the allele-specific antigen-binding site on I-Ak and I-Ab molecules

Residues 46 and 54 on a pigeon cytochrome c 43-58 analog, 50E, function as major histocompatibility complex class II contact sites. A peptide, 46F50E54A, with phenylalanine (F) at position 46 and alanine (A) at 54 on 50E bound to Ab and a peptide, 46D50E54A, with aspartic acid (D) at 46 and alanine at 54, bound to Ak. To determine the allele-specific peptide contact sites on I-A molecules corresponding to the I-A contact sites of the peptides, we analyzed responses of Ak- and/or Ab-restricted T cell hybridomas to 46F50E54A or 46D50E54A using L cell transfectants expressing recombinant I-A molecules between Ak and Ab or point mutants of Ak as antigen presenting cells. It was shown that the N-terminal half of the alpha helix of the A alpha chain determined the allele-specific T cell responses. Furthermore, with arginine (k type amino acid) or alanine (b type amino acid) at position 56 of the Ak alpha chain, these T cell hybridomas were stimulated predominantly by 46D50E54A (Ak binding peptide) or 46F50E54A (Ab binding peptide), respectively. Thus, the amino acid at position 56 of the A alpha chain determines allele-specific antigen presentation. This postulate was confirmed by direct binding analysis of 50E analogs of various I-A molecules. A single amino acid change (arginine to alanine) at position 56 of the Ak alpha chain altered the peptide binding specificity (46D50E54A to 46F50E54A).

Analysis of neurotrophin-3 expression using the lacZ reporter gene suggests its local mode of neurotrophic activity

We replaced the mouse neurotrophin-3 gene with the Escherichia coli-derived lacZ gene by means of homologous recombination. The mice with this mutation were useful models for studying the distribution of neurotrophin-3 expression in vivo, because visualization by 5-bromo-4-chloro-3-indoyl-beta-D-galactopyranoside (X-Gal) staining was simple and rapid compared with in situ hybridization or immunohistochemistry. Whole-mount staining of mutant embryos at embryonic day 10 revealed that lacZ, a reporter for the neurotrophin-3 gene, was expressed in the mesencephalon, mandibular arch and somites. In the embryos at days 13-17, lacZ was markedly expressed in the peripheral target tissues of sensory and sympathetic neurons. We also found that spinal motor neurons and sensory neurons in trigeminal and dorsal root ganglia express lacZ. Some of these X-Gal staining regions overlapped with the sites expressing trkC, a high-affinity receptor for neurotrophin-3. The distribution of X-Gal staining in heterozygotes and homozygotes was similar to that of neurotrophin-3 messenger RNA detected by in situ hybridization. However, there was less lacZ expression in the dorsal root ganglia of homozygotes than neurotrophin-3 expression in wild-type mice. These results suggest that the neurotrophin-3 produced in the dorsal root ganglia also plays a role in the survival of some of the neurotrophin-3-positive neurons and that the local mode of neurotrophic activity is widely distributed.

Fgr expression restricted to subpopulation of monocyte/macrophage lineage in resting conditions is induced in various hematopoietic cells after activation or transformation

The c-fgr gene product (Fgr) is a member of the src-family of protein tyrosine kinases. We have established a monoclonal antibody (2H2) which recognizes the unique N-terminal domain of the murine Fgr. In the present study, using immunohistochemical analysis and immune complex kinase assay with the 2H2, we investigated expression of Fgr in various cell populations and tissues in a murine system. In resting conditions, Fgr expression was confined to subsets of a monocyte/macrophage lineage. Thus, Fgr+ cells were detected in paracortical areas and medullas of lymph nodes, but seen only in marginal zones of the spleen and the medulla of the thymus. No Fgr+ macrophage was detected in other tissues, Peyer's patches, brain, heart, lung, liver, pancreas, kidney and peritoneal cavity. However, immune complex kinase assay revealed that, upon stimulation, T and B cells as well as peritoneal macrophages expressed significant levels of Fgr molecules. Transformed cell lines of lymphoid origin, EL-4 and LK35.2, which are T and B lineage lymphomas, respectively, also expressed Fgr molecules. Thus, various cells of hematopoietic origin appeared to possess a potentiality to express Fgr following activation or transformation. The present findings may help elucidate the functional significance of Fgr in immunologically committed cells in either activated or non-activated conditions.

An EcoRI RFLP in human APC gene

A novel EcoRI-restriction fragment length polymorphism in the genomic sequence of the human adenomatous polyposis coli (APC) gene is described. This polymorphism in the APC gene would be very useful for examination of segregation of the mutated APC gene in the kindreds of familial adenomatous polyposis, and also for studying the loss of heterozygosity at the APC region in certain tumors.

Biallelic inactivation of the APC gene in hepatoblastoma

Familial adenomatous polyposis (FAP) is an inherited disorder caused by germline mutation of the adenomatous polyposis coli (APC) gene. Increased risk of hepatoblastoma (HBL) in FAP kindreds has been reported. To determine whether inactivation of the APC gene plays a role in development of HBL, 13 sporadic infantile hepatic tumors were analyzed for genetic alterations in the APC gene. A PCR-mediated RNase protection analysis was performed to detect subtle genetic alterations in the mutation cluster region and in exons 3 and 4 of the APC gene. The results showed that a G to T transversion at the splice acceptor site of the intron 3-exon 4 junction had occurred in one HBL. Sequence analysis of normal tissue of the patient proved the mutation to be germinal. Southern blot analysis at the APC locus revealed that the tumor had lost the opposite allele and was isodisomic at this locus. RNA analysis indicated that the tumor contained only the small APC transcript, from which exon 4 was entirely absent. Since abnormal splicing causes termination due to frameshift, it was hypothesized that only the truncated APC protein was expressed in this tumor. These findings suggest that inactivation of the APC gene is closely related to tumorigenesis of HBLs in FAP patients.

Neurotrophin-3 is expressed in the posterior lobe of mouse cerebellum, but does not affect the cerebellar development

We replaced the neurotrophin-3 (NT-3) gene with Escherichia coli-derived lacZ via homologous recombination in embryonic stem (ES) cells and generated the mutant mice. Here we show the in vivo expression of NT-3 in the cerebellum during the postnatal period. A high level of lacZ expression was found in the granular layer of posterior lobe (lobules VII to X) in the postnatal NT-3(+/-) cerebellum. The expression in these regions was reduced with age. Although the Purkinje cells are considered to be a target of NT-3 and the NT-3(-/-) mice displayed severe moving disorders like ataxia, no histological abnormality was observed in their cerebellum. These findings suggest that the NT-3 expressed in the cerebellum gives some trophic effects primarily to the posterior lobe, however, the deficiency does not affect its development.

[Determination of a peptide deduced from the influenza virus haemagglutinin that induces human class II-restricted T cell responses in DQ6 transgenic mice]

HLA-DQ6 (DQ6) transgenic mice were immunized with a set of peptides deduced from either a fragment of the haemagglutinin (HA) of influenza A/Aichi/2/68 virus (HA123-138) or pigeon cytochrome c 43-58 (p43-58) analogues. HA123-138 induced a moderate level of T cell responses in DQ6 transgenic mice. The T cell responses were shown to be restricted to either the DQ6 or I-Ab molecule. We then established T cell hybridomas specific for HA123-138 and restricted to DQ6 from DQ6 transgenic mice immunized with the HA123-138. These T cell hybridomas were activated by the stimulation with HA123-138 in the presence of an HLA-DQ6 transfectant or a paraformaldehyde-fixed HLA-DQ6 positive EB cell line. Using one of these T cell hybridomas we searched for potent peptides which showed high antigenicity as compared with HA123-138. We found that a hybrid peptide antigen, 46F/HA126-134/54A, which was composed of HA126-134 and the I-Ab binding component (46F/54A) previously determined on p43-58 analogues evoked considerable responses in the HA123-138 specific T cell hybridoma. Competitive inhibition assay with this T cell hybridoma and direct binding assay using a DQ6 positive EB cell line or DQ6-transfected L cells showed consistently that the agretopic position 46 of the p43-58 analogues and hybrid peptide antigens was preserved among DQ6-restricted T cell responses and murine class II, I-A, restricted T cell responses. Phenylalanine (F) at the position 46 appeared to be a critical residue for binding to HLA-DQ6 as had been shown for binding to I-Ab.

Targeted disruption of the neurotrophin-3 gene with lacZ induces loss of trkC-positive neurons in sensory ganglia but not in spinal cords

We have replaced the NT-3 gene with Escherichia coli-derived lacZ gene by means of homologous recombination in embryonic stem cells and thus produced null mutant mice. Mice homozygous for this mutation developed to birth, but most of them could not suck well and died within 2 days after birth. The surviving homozygous mutant mice displayed movement disorder similar to ataxia. The expression of lacZ was widely distributed in the target tissues of peripheral nerves, spinal motor neurons, lumbar dorsal root ganglia and trigeminal ganglia during the prenatal periods. A neuroanatomical examination revealed that there was marked cell reduction present in trigeminal and lumbar dorsal root ganglia in the developing homozygous mutant mice. In these tissues, the expression of trkC, a high-affinity receptor for NT-3, was markedly reduced. In contrast, we did not find any morphological abnormalities, significant cell loss or decreased levels of trkC expression in the motor neurons present in the ventral horn of the spinal cord. These results indicate that the absence of the NT-3 gene leads to a defect in the sensory nervous system, but it may be complemented by other neurotrophins in the motor nervous system during the development.

Determination of the agretopic residues of a peptide co-restricted to different class II isotypes, I-Au and I-Eu, and its application for preparation of a synthetic peptide vaccine against influenza virus A/Aichi/2/68

We have defined that residues 46 and 54 on a synthetic peptide composed of residues 43-58 of pigeon cytochrome c (p43-58) work as agretopes (sites bound to an MHC molecule) in I-Ab mice. Substitution of amino acid residues on these positions altered the peptide to bind with the other MHC molecules. Furthermore, by substituting the agretopic residues with a variety of amino acids, we could determine the class II binding motif for each MHC molecule. In the present study, immunogenicity of a peptide, 46R50V54A, carrying valine (V) at epitopic (site bound to TCR) position 50, arginine (R) and alanine (A) at agretopic positions 46 and 54 of the p43-58, respectively has been analyzed in B10.PL (H-2u) mice. We found that this peptide bound to two different class II isotypes, I-Au and I-Eu. Arginine at position 46 or alanine at position 54 of the 46R50V54A was shown to be critical for binding to I-Au or I-Eu, respectively. Further, on the basis of this class II binding motif we could prepare potent peptide vaccines against influenza A/Aichi/2/68 virus in B10.PL mice.

A frequent alteration of p53 gene in carcinoma in adenoma of colon

In general, colorectal carcinoma is thought to originate mainly from adenoma, and this pathway is called the adenoma-carcinoma sequence. Carcinoma in adenoma is an appropriate model for analysis of this mechanism, because adenoma and carcinoma tissues coexist in the same polyp and the carcinoma is thought to have originated from the surrounding adenoma. Expression of the p53 protein was analyzed in 36 cases of carcinoma in adenoma in the colon by immunohistochemistry using an anti-human p53 monoclonal antibody (PAb1801). Alterations of the p53 gene were analyzed by the polymerase chain reaction for microanalysis of normal mucosa, adenoma, and carcinoma from histological slides. Mutations were assessed by the polymerase chain reaction-single strand conformation polymorphism analysis and identified by DNA sequencing in some cases. Loss of heterozygosity was studied by polymerase chain reaction-restriction fragment length polymorphism analysis. Positive staining for p53 was detected in three (8%) of 37 adenomas and 20 (53%) of 38 focal carcinomas. One (7%) of 15 adenomas with mild dysplasia, three (14%) of 22 adenomas with moderate dysplasia, and 16 (42%) of 38 focal carcinomas had a mutation in exon 5 through exon 8 of the p53 gene. As for allelic loss in the p53 gene locus, only one adenoma with moderate dysplasia had loss of heterozygosity, whereas six (40%) of 15 focal carcinomas had loss of heterozygosity. Of those tumors (3 of 37 adenomas and 20 of 38 focal carcinomas) that reacted with PAb1801, 78% (18 of 23) showed genetic alterations. Among 52 tumors which showed negative staining, five tumors had a p53 mutation and four of them were nonsense mutations. Putting all of these results together, 71% (24 of 34) of the cases underwent p53 gene and protein alterations during the conversion from adenoma to focal carcinoma. These data clearly indicate that genetic alterations of p53 are involved mainly in the malignant transformation from adenoma to focal carcinoma in colon carcinogenesis. In addition, some cases show heterogeneity of the p53 gene in carcinoma in adenoma of the colon. There may be other pathways than p53 responsible for malignant change in the colon.

Analysis of epitopic residues introduced into the hybrid peptide vaccines prepared according to the cassette theory

In our previous study, we prepared a synthetic peptide vaccine (46F/HA127-133/54A) against influenza strain A/Aichi/2/68 (H3N2) virus by introducing haemagglutinin (HA) 127-133 to an I-Ab,b binding component that consisted of residues 43-46 and 54-58 of an I-Ab,d binding peptide, 46F50V54A. This hybrid peptide vaccine induced considerable immunological responses against A/Aichi/2/68 as well as against the peptide vaccine in I-Ab mice. In the present study, we have attempted to increase the immunogenicity of the peptide vaccine by introducing HA peptides of various lengths into the I-Ab,d binding components consisting of residues 43-46 and 54-58 or 43-47 and 53-58 of 46F50V54A. We demonstrate here that, among the peptide vaccines prepared, 46F/HA127-133/54A (18 mer) consisting of HA127-133 and the I-Ab,d binding component constructed from 43-47 and 53-58 of 46F50V54A induces the most vigorous T-cell responses and neutralizing antibodies against A/Aichi/2/68 in both I-Ab and I-Ad mice.

[Muscular sarcoidosis]

Sarcoidosis is a multisystem granulomatous disorder of unknown etiology presenting with bilateral hilar lymphadenopathy, pulmonary, skin, and eye lesion. Sarcoidosis involving skeletal muscle is not uncommon because non caseating granuloma have been demonstrated in as much as 50 to 80% of sarcoidosis cases. Symptomatic muscle involvement, however, is rare. Chronic and acute myopathy and palpable nodular lesions due to sarcoidosis involving skeletal muscle have been reported. Chronic myopathy is progressive muscle disease with muscle weakness and wasting. Because this syndrome is rare, its natural history and responsiveness to corticosteroid have not been defined well. We review the medical literature of previously reported cases of muscular sarcoidosis.

A meiotic DNA polymerase from a mushroom, Agaricus bisporus

A meiotic DNA polymerase [DNA nucleotidyltransferase (DNA-directed), EC 2.7.7.7], which likely has a role in meiotic DNA repair, was isolated from a mushroom, Agaricus bisporus. The purified fraction displays three bands in SDS/PAGE, at molecular masses of 72 kDa, 65 kDa and 36 kDa. Optimal activity is at pH 7.0-8.0 in the presence of 5 mM Mg2+ and 50 mM KCl and at 28-30 degrees C, which is the temperature for meiosis. This enzyme is resistant to N-ethylmaleimide and sensitive to 2',3'-dideoxythymidine 5'-triphosphate, suggesting that it is a beta-like DNA polymerase. These characteristics are similar to those of Coprinus DNA polymerase beta [Sakaguchi and Lu (1982) Mol. Cell. Biol. 2, 752-757]. In Western-blot analysis, the antiserum against the Coprinus polymerase reacts only with the 65 kDa band, which coincides with the molecular mass of the Coprinus polymerase. Western-blot analysis also showed that the antiserum could react with crude extracts not only from the Agaricales family, to which Agaricus and Coprinus belong, but also from different mushroom families and Saccharomyces. The Agaricus polymerase activity can be found only in the meiotic-cell-rich fraction, but the enzyme is also present in the somatic cells in an inactive state.

Determination of amino acids on agretopes of pigeon cytochrome c-related peptides specifically bound to I-A allelic products

In our prior study it was demonstrated that residues 46 and 54 on a synthetic peptide, AEGFSYTVANKNKGIT (50V), work as an agretope (site contacts with major histocompatibility complex molecules) and residues 50 and 52 function as an epitope (site contacts with T cell receptor), when tri-molecular complexes are formed among 50V,I-Ab and the T cell receptor. 50V was composed of residues 43 to 58 of pigeon cytochrome c (p43-58) except that the aspartic acid (D) at residue 50 was substituted by valine (V). Substitution of agretopic residues on 50V changed this I-Ab-binding peptide to an I-Ak-binding peptide, suggesting that positions 46 and 54 work as an agretope in I-Ak-restricted T cell responses. In the present study we examined whether residues 46 and 54 of 50V worked as agretopes in T cell responses restricted to other I-A haplotypes. The 50V-related peptides with phenylalanine (F) at position 46 and alanine (A) at position 54 bound tightly to I-Ab, I-Ad, I-Aq and I-As molecules and stimulated T cells most potently in mice bearing these I-A haplotypes. In contrast, 50V-related peptides carrying D at position 46 and A at position 54 bound most potently to I-Ak molecules, and the peptides with arginine (R) at position 46 and A at position 54 bound most efficiently to I-Av molecules. The present findings, thus, demonstrate that the agretopic positions on the p43-58 related peptides are preserved in T cell responses restricted to each I-A haplotype studied, and that the specific amino acids on the agretopic positions exist a priori for each I-A allele-specific structure.

A meiotic DNA polymerase from Coprinus cinereus: further purification and characterization

A meiotic DNA polymerase that is present at a high level of activity in meiotic cells of a basidiomycete, Coprinus cinereus, was purified to near homogeneity using synthetic RNA homopolymer [poly(C)] cellulose column chromatography. This report presents the first extensive purification and characterization of any eukaryotic DNA polymerase having a role in meiosis. This enzyme is a single polypeptide with a molecular mass of 65,000. Activity in this enzyme requires magnesium ions and occurs at an optimal pH of 7.5. It is strongly inhibited by dideoxythymidine triphosphate but is relatively insensitive to aphidicolin and N-ethylmaleimide and can use poly(C)/oligo(dG)12-18 as a template-primer. Polymerase activity can be found only in cells at meiotic prophase, even though the enzyme has been identified in somatic cells in an inactive state using immunoblot analysis. Its distinctive distribution makes possible a genetic and biochemical analysis of functional role of a meiotic DNA polymerase in meiotic recombination, repair and synthesis.

Isolation of region-specific cosmids by hybridization with microdissection clones from human chromosome 10q11.1-q21.1

A region-specific plasmid library composed of 20,000 recombinants was constructed by microdissection of human chromosome 10 (10q11.2-q21.1) and subsequent amplification with the primer-linker method of polymerase chain reaction (PCR). Hybridization with total human DNA showed that 32 of 217 microclones studied contained highly repetitive sequences. Further analysis of the remaining 185 microclones proved that 43 microclones, each having an insert longer than 200 bp, contained unique sequences of human chromosome 10 origin. Twenty-five microclones randomly selected from the 43 were used directly as probes to isolate corresponding cosmid clones, resulting in 32 cosmids corresponding to 14 microclones. Of the 25 cosmids that could be mapped by fluorescence in situ hybridization, 24 proved to originate from the microdissected or adjacent region (10p11.2-q22.3) and 1 from a rather distal region (10q24.3-q25.1). In addition, 15 of the 32 cosmids revealed restriction fragment length polymorphisms, including 1 with a variable number of tandem repeats marker. The microdissection library and the obtained cosmids are valuable resources for constructing high-resolution physical and linkage maps of the pericentromeric region of chromosome 10, where the gene predisposing to multiple endocrine neoplasia type 2A (MEN2A) has been mapped.

A further study on the left-right asymmetry of the planum temporale

By means of a rubbed copy method using India ink and an image-analysis system (IBAS 2000), the areas of 106 left-right plana temporalia were compared using fixed brains of both sexes. The left planum was of a larger size than the right planum in two-thirds of the cases. This result was confirmed statistically by the least-squares analysis of variance method (p < 0.01).