Biomedical subjects

Hirokazu Inoue

Publications and source records attributed to Hirokazu Inoue.

10 recordsLinked to original sources

PubMed2003

Isolation and genetic characterization of the Neurospora crassa REV1 and REV7 homologs: evidence for involvement in damage-induced mutagenesis.

In a previous paper, we reported that the Neurospora crassa upr-1 gene is a homolog of the yeast gene REV3, which encodes the catalytic subunit of DNA polymerase zeta (polzeta). Characterization of the upr-1 mutant indicated that the UPR1 protein plays a role in DNA repair and mutagenesis. To help understand the mechanisms of mutagenic DNA repair in the N. crassa more extensively, we identified N. crassa homologs of yeast REV1 and REV7 and obtained mutants ncrev1 or ncrev7, which had similar phenotypes to the upr-1 mutant. Mutant carrying ncrev7 was more sensitive to UV and 4NQO, and slightly sensitive to MMS than the wild-type. The sensitivity to UV and MMS of the ncrev1 mutant was moderately higher than that of the wild-type, but the sensitivity to 4NQO of the mutant was similar to that of the wild-type. In reversion assay using testers with base substitution or frameshift mutation at the ad-3A locus, each of ncrev1 and ncrev7 mutants showed lower induced-mutability than the wild-type. Expression of ncrev1 and ncrev7 was found to be UV-inducible like the case of upr-1. Genetic analyses showed that the ncrev7 was identical to mus-26, which belongs to the upr-1 epistasis group, and that the ncrev1 was a newly identified DNA repair gene and designated as mus-42. Interestingly, all three mutants have a normal CPD photolyase gene, however, they showed a partial photoreactivation defect (PPD) phenotype, not completely defective but inefficient in photoreactivation. These results suggest that N. crassa REV homolog genes function in DNA repair and UV mutagenesis through the bypass of (6-4) photoproducts.

DNA↗

PubMed2003

Pro-apoptotic ASY/Nogo-B protein associates with ASYIP.

We have previously shown that ectopic expression of the ASY/Nogo-B gene induced apoptosis in various cancer cell lines. Nogo-A, a splice variant of the ASY, has been reported to have an inhibitory effect on neuronal regeneration in the central nervous system. To investigate the mechanism of ASY-induced apoptosis or inhibition of neuronal regeneration, we cloned a cDNA for the ASY-interacting protein from the human cDNA library using the yeast two-hybrid method, and obtained a cDNA we designated as ASYIP. The ASYIP protein contains two hydrophobic regions and a double lysine endoplasmic reticulum (ER) retrieval motif at its C-terminus, which was shown to be identical to RTN3, a reticulon family protein of unknown function. We showed that ASY and ASYIP proteins formed a complex also in human cells. Mutational analysis indicated that both of the hydrophobic regions of the ASYIP protein were required for the association. By immunofluorescence analysis, the ASYIP protein was shown to be co-localized with ASY in the ER. Characterization of the ASYIP gene may be very useful in clarifying the mechanism of ASY-induced apoptosis or Nogo-involved inhibition of neuronal regeneration in the central nervous system.

Amino Acid Sequence↗

PubMed2003

PEG with introducer or pull method: a prospective randomized comparison.

BACKGROUND: PEG by the conventional pull method has the potential drawback of being associated with a higher frequency of wound infection, presumably caused by contamination of the gastrostomy catheter as it passes through the oral cavity. This study investigated the occurrence of peristomal wound infection after PEG placement by using the pull and introducer techniques. METHODS: Between September 1999 and May 2002, consecutive patients with dysphagia for whom PEG was recommended were enrolled in the study and randomly assigned to two groups: PEG with the introducer method (Group I) or PEG with the pull method (Group II). The peristomal area of each patient was evaluated on a daily basis for one week after PEG. Erythema and exudate were scored on a scale from 0 to 4 and induration on a scale of 0 to 3. Criteria for infection were a maximum combined score of 8 or higher, or the presence of microscopic and microbiologic evidence of suppurating exudate. In each group, the endoscope was passed once during the procedure, and an antibiotic (piperacillin) was given prophylactically. All procedures were performed by one investigator with the assistance of another physician. RESULTS: Of the 60 patients enrolled, 30 were assigned to each group. PEG was successful in all patients. One patient was excluded from each group because of death (Group I, stroke; Group II, myocardial infarction) within one week of the procedure. Therefore, 58 patients, 29 in each group, were evaluated. There was no significant difference between the groups in terms of clinical parameters (age, gender, disease, performance score, mode of previous feeding, and recent antibiotic exposure). The occurrence of peristomal infection within one week of PEG was lower in Group I (introducer method) (0 vs. 9; p = 0.00094). The mean daily combined scores in Group I were significantly lower than those in Group II. Median of maximum parameter scores in Group I were significantly lower than those in Group II. There were no procedure-related mortalities or clinically significant wound infections that required surgical intervention. CONCLUSIONS: The risk of peristomal wound infection after PEG is lower with the introducer method compared with the pull method.

Aged↗

PubMed2003

Down-regulation of drs mRNA in human prostate carcinomas.

We have previously reported that the drs gene has the ability to suppress transformation by v-src and v-K-ras in the rat cell line F2808. We have also shown that the expression of drs mRNA is markedly reduced in a variety of human cancer cell lines, suggesting that down-regulation of drs mRNA is correlated with the development of human cancers. To clarify the role of the drs gene in prostate carcinogenesis, we examined the expression of the drs gene in 3 normal prostate, 13 prostate carcinoma, 5 benign prostate hyperplasia (BPH), and 2 prostatic intraepithelial neoplasia (PIN) tissue specimens by in situ hybridization and in 3 prostate carcinoma cell lines (PC3, LNCaP, and DU145) and 2 BPH tissues by Northern blot analysis. Furthermore, the deletion, and rearrangement of the drs gene were analyzed by Southern blot analysis. The drs mRNA was significantly expressed in normal prostate and BPH tissues, whereas it was markedly down-regulated in prostate carcinoma tissues and prostate carcinoma cell lines. In 2 tissues from PIN, drs mRNA was weakly expressed. There were no differences between prostate carcinoma cell lines and BPH tissues in terms of their banding patterns of Southern blot analysis. These results indicate that down-regulation of drs mRNA is closely correlated with development of prostate carcinoma, suggesting a tumor-suppressor function of the drs gene in this cancer.

Adenocarcinoma↗

PubMed2003

Enhanced genomic instability and defective postreplication repair in RAD18 knockout mouse embryonic stem cells.

In lower eukaryotes, Rad18 plays a crucial role in postreplication repair. Previously, we isolated a human homologue of RAD18 (hRAD18) and showed that human cells overexpressing hRad18 protein with a mutation in the RING finger motif are defective in postreplication repair. Here, we report the construction of RAD18-knockout mouse embryonic stem cells by gene targeting. These cells had almost the same growth rate as wild-type cells and manifested phenotypes similar to those of human cells expressing mutant Rad18 protein: hypersensitivity to multiple DNA damaging agents and a defect in postreplication repair. Mutation was not induced in the knockout cells with any higher frequencies than in wild-type cells, as shown by ouabain resistance. In the knockout cells, spontaneous sister chromatid exchange (SCE) occurred with twice the frequency observed in normal cells. After mild DNA damage, SCE was threefold higher in the knockout cells, while no increase was observed in normal cells. Stable transformation efficiencies were approximately 20-fold higher in knockout cells, and gene targeting occurred with approximately 40-fold-higher frequency than in wild-type cells at the Oct3/4 locus. These results indicate that dysfunction of Rad18 greatly increases both the frequency of homologous as well as illegitimate recombination, and that RAD18 contributes to maintenance of genomic stability through postreplication repair.

Amino Acid Motifs↗

PubMed2002

Suppression of anchorage-independent growth of human cancer cell lines by the TRIF52/periostin/OSF-2 gene.

In searching for genes that suppress the viral transformation of primary cells, we have isolated a number of TRIF (transcript reduced in F2408) genes that are expressed well in primary rat embryo fibroblasts (REFs) but poorly in spontaneously immortalized rat fibroblast cell lines derived from REFs. One of these genes, TRIF52, is a rat homologue of the mouse protein periostin, which is suspected of being involved in oncogenesis. We found here that periostin mRNA expression is markedly downregulated in a variety of human cancer cell lines and human lung cancer tissues. Human cancer cell lines with reduced endogenous periostin gene expression that were infected with a recombinant retrovirus containing the periostin gene had reduced anchorage-independent growth. Mutational analysis revealed that the C-terminal region of periostin is sufficient to convey the anchorage-independent growth-suppressive activity of the protein. These observations together suggest that periostin may serve to inhibit the development of human cancers by acting as a tumor suppressor.

Cell Adhesion Molecules↗

PubMed2002

Isolation of a novel mouse variant of the drs tumor suppressor gene.

The drs gene was isolated as a transformation suppressor against the v-src oncogene. Drs protein has a transmembrane domain and three consensus repeats (CRs) called Sushi motifs in the extracellular domain. The drs gene also has the ability to suppress anchorage-independent growth of human cancer cell lines. In this paper, we report the isolation of a novel variant cDNA of mouse drs (mDRS-2) containing two CRs, in addition to a mouse homolog of drs (mDRS-1) containing three CRs. We investigated the suppressor function of these mDRS cDNAs in human cancer cells and found that the lack of one CR is critical for suppression of anchorage-independent growth by drs.

3T3 Cells↗

PubMed2002

X-linked thrombocytopenia in a girl.

We report X-linked thrombocytopenia (XLT) in a 6-year-old girl with petechiae and thrombocytopenia from the age of 3 months. Her 2-year-old brother was also diagnosed with XLT. The Wiskott-Aldrich syndrome protein (WASP) gene was detected as a replacement of +5th G to Aon intron 6 using sequence analysis, and the WASP expression levels in this patient were one-third those of a healthy control. The X-inactivation analysis of the patients lymphocytes showed a random pattern of X-chromosome inactivation. To our knowledge, this is the first confirmed report of XLT in a female.

Child↗

PubMed2002

Expression of drs mRNA in human lung adenocarcinomas.

The drs gene was originally isolated from a rat primary embryo fibroblast cDNA library as a suppressor gene against v-src transformation. We have previously shown that expression of drs mRNA was markedly reduced in a variety of human cancer cell lines, including those of the colon, bladder, and ovary. Furthermore, introduction of drs cDNA by retrovirus vector into these cancer cell lines caused suppression of anchorage-independent growth without affecting cell proliferation. These findings suggest that down-regulation of drs mRNA is closely correlated with expression of malignant phenotypes in development of human cancers. To clarify the correlation between down-regulation of drs mRNA and malignant tumor formation in human tumor tissues, we examined the expression of drs mRNA in well-differentiated, moderately differentiated, and poorly differentiated lung adenocarcinoma tissues by in situ mRNA hybridization. The results clearly indicated that expression of drs mRNA was markedly reduced in 5 of 5 poorly differentiated lung adenocarcinomas examined but significantly expressed in normal lung tissues and 5 of 7 moderately-differentiated and 3 of 5 well-differentiated lung adenocarcinoma tissues. Neither gross deletion nor rearrangement of the drs genome was detected in these tissues. Down-regulation of drs mRNA was also observed in human lung adenocarcinoma cell lines derived from poorly differentiated adenocarcinomas. Our results suggest that down-regulation of drs mRNA is correlated with a poor degree of differentiation and progression of lung adenocarcinoma.

Adenocarcinoma↗

PubMed2002

Down-regulation of drs mRNA in colorectal neoplasms.

The drs gene was originally isolated as a transformation suppressor gene against the v-src oncogene. Expression of drs mRNA is down-regulated by retroviral oncogenes such as v-src and v-K-ras in the rat cell line F2408. Expression of drs mRNA is also markedly reduced in a variety of human cancer cell lines, including those of carcinomas of the colon, bladder, and ovary, suggesting that down-regulation of drs mRNA is correlated with the development of human cancers. To clarify the correlation between down-regulation of the drs gene and malignant tumor formation in human colorectal neoplasms, we examined expression of drs mRNA in a variety of colon cancer tissues by in situ hybridization. A total of 53 morphologically distinct neoplastic specimens were divided into the following five groups according to morphology: low and high grade adenoma in 7 and 12 cases, respectively (groups A, B), protruded-type carcinoma in 16 (group C), superficial-type carcinoma with an adenomatous component in 10 (group D) or superficial-type carcinomas without any adenomatous component in 8 (group E). Expression of drs mRNA was detected in normal mucosa, low-grade adenoma and most superficial-type carcinomas without any adenomatous component. On the other hand, the rate of drs mRNA expression was significantly lower in protruded-type adenocarcinoma and superficial-type carcinoma with an adenomatous component. Our results indicate that down-regulation of drs mRNA is closely correlated with carcinomas which arise from adenomatous polyps in the course of the adenoma-carcinoma sequence, but that most carcinomas arising de novo are independent of the tumor suppressor function of the drs gene.

Adenoma↗