Biomedical subjects

H Horiguchi

Publications and source records attributed to H Horiguchi.

At least 19 recordsLinked to original sources

PubMed2005

Identification of equol producers in a Japanese population by high-performance liquid chromatography with coulometric array for determining serum isoflavones.

Using a method of high-performance liquid chromatography (HPLC) with coulometric array, we measured isoflavone levels in sera from seven volunteers before and after three days of ingesting Soyaflavone E (an isoflavones powder) and from 129 female farmers (Japanese Multiple Environmental Toxicants Study; JMETS). Results showed that the serum isoflavone concentrations rose dramatically after three days of ingesting Soyaflavone E in all subjects except for the serum equol concentrations in two subjects. The geometric mean concentrations of daidzein, genistein, and equol in the serum of 129 Japanese women were 25.0 ng/ml of daidzein, 94.1 ng/ml of genistein, and 9.6 ng/ml of equol. Interestingly, there existed two dominant groups in terms of serum equol concentrations in an independent manner of soy-derived product intake among the study participants.

Adult↗

PubMed2004

Isolation and characterization of resident macrophages from the smooth muscle layers of murine small intestine.

Macrophages within the murine tunica muscularis were isolated and cultured for physiological studies. Following dispersion, macrophages were identified by phagocytotic activity of fluorescein isothiocyanate (FITC)-dextran. Immediately following isolation, macrophages were rounded and possessed fluorescent granula but developed a ramified shape after 3-4 days in culture. Resident and cultured macrophages were immunopositive for F4/80 and I-Ad/I-Ed. Greater than 90% of F4/80 positive cultured cells were FITC-dextran positive. Macrophages had resting membrane potentials (RMP) of -33.3 +/- 1.5 mV after 1 day in culture, which increased to -53.9 +/- 4.4 mV after 3-4 days. The change in RMP was associated with the development of an inward rectifying K+ current, and a decrease in a voltage-dependent, inactivating outward current. After 3-4 days in culture the inflammatory mediated substances adenosine triphosphate (ATP), platelet-activating factor and bacterial lipopolysaccharide induced increases in cytoplasmic Ca2+ ([Ca2+]i). Forskolin suppressed the ATP-induced increase in [Ca2+]i. Macrophages exhibited oxidative bursts, measured by oxidation of dihydrorhodamine-123 to rhodamine-123. Oxidative bursts coincided with a reduction in intracellular pH. Macrophages expressed a proton conductance that may participate in pH maintenance during reactive oxygen production. These results suggest that resident macrophages in the intestine may play a role in the immunological protection of the gut.

Animals↗

PubMed2002

[Clinical analysis of surgically resected multiple primary lung cancer].

Synchronous and metachronous lung cancer is occasionally encountered. Frequency of the occurrence is increasing because of recent progress of imaging technique such as high resolution CT and CT based annual lung survey. We analyzed clinical characteristics of both synchronous and metachronous lung cancer treated surgically in our facility. There were 20 cases of multiple lung cancer cases, which is consisted of 12 synchronous multiple lung cancer cases and 8 metachronous lung cancer cases. Mean age was 62 years old and there were 14 male and 6 female cases. Among synchronous group, 8 cases have multiple shadow in ipsilateral hemithorax and 4 cases in both side. Surgery was carried out according to the extent of the disease and lung reserve. Associated cancer was diagnosed stage IA or IB in all cases. Five-year survival was 58.9%. Meanwhile, as regards to metachronous group, mean interval between first cancer and second cancer was 73 months. Seven cases have contralateral second primary lung cancer and one case has ipsilateral second primary lung cancer. In 3 cases, histology of the first and the second disease were different and in 5 cases that were the same. The first procedures were complete resection with systemic mediastinal LN dissection. The second procedures were determined based on the lung reserve. Pathological stage of the second disease were either stage IA or IB. There were no operative mortality and 5 years survival was 75%. Since there is no operative mortality and the outcome seems satisfactory when the patient has enough lung reserve, aggressive surgical resection should be considered in the case of multiple primary lung cancer. There is an increasing chance of synchronous multiple primary lung cancer because of improvement of imaging system. We have to prepare new therapeutic strategy for those patients.

Aged↗

PubMed2001

Dexamethasone prevents acute cadmium-induced hepatic injury but exacerbates kidney dysfunction in rabbits.

Cadmium is a potent hepatotoxicant for which neither effective preventive methods nor the mechanism of toxicity has been established. We investigated the preventive effect of dexamethasone against cadmium toxicity on cadmium-induced liver injury in rabbits. Pretreatment with dexamethasone at 1 mg/kg increased the rate of survival in rabbits administered 2.5 mg/kg iv cadmium. Cadmium induced acute severe liver injury characterized by hepatocellular necrosis, infiltration by inflammatory cells, and increases of plasma GOT, GPT, LDH, and LDH5. Dexamethasone mitigated the acute hepatotoxic effect of cadmium, but exacerbated cadmium-induced kidney dysfunction, with destruction of renal tubular cells and increases in excretion of protein, glucose, and amino acids into urine. The cadmium concentration in liver and kidney of rabbits administered cadmium was not changed by dexamethasone pretreatment. Although metallothionein mRNA expression induced by cadmium was not affected by dexamethasone in liver or kidney, cadmium-induced metallothionein protein production was augmented at the early phase in liver and decreased at the later phase in kidney. Neutrophilia observed after cadmium administration was enhanced initially by dexamethasone pretreatment. These results indicate that dexamethasone pretreatment potently prevented cadmium-induced liver injury, but exacerbated renal tubular dysfunction.

Amino Acids↗

PubMed2001

Characterization of hnRNP A2 and B1 using monoclonal antibodies: intracellular distribution and metabolism through cell cycle.

Heterogeneous nuclear ribonucleoprotein (hnRNP) A2/B1 are nuclear RNA binding proteins involved in pre-RNA processing. The alternative splicing of the second mini exon of A2/B1 gene produces A2 and less abundant B1. It has been reported that patients with autoimmune diseases frequently have blood autoantibody valence for A2/B1, and recently that the overexpression, especially of B1, is useful for detecting cancers in early stage. Three anti-A2/B1 monoclonal antibodies were developed using recombinant A2 protein and synthesized peptides around the second splicing site. Three antibodies could separately recognize A2 and B1, and their specificity made them useful in the study of the biochemical and functional properties of A2 and B1. These antibodies have demonstrated differences between A2 and B1 in the intracellular distribution and in the metabolism through cell cycle. They are valuable reagents to clarify the clinical significance of A2/B1 in autoimmune diseases and cancers.

Amino Acid Sequence↗

PubMed2001

Antioxidant system within yeast peroxisome. Biochemical and physiological characterization of CbPmp20 in the methylotrophic yeast Candida boidinii.

Candida boidinii Pmp20 (CbPmp20), a protein associated with the inner side of peroxisomal membrane, belongs to a recently identified protein family of antioxidant enzymes, the peroxiredoxins, which contain one cysteine residue. Pmp20 homologs containing the putative peroxisome targeting signal type 1 have also been identified in mammals and lower eukaryotes. However, the physiological function of these Pmp20 family proteins has been unclear. In this study, we investigated the biochemical and physiological functions of recombinant CbPmp20 protein in methanol-induced peroxisomes of C. boidinii using the PMP20-deleted strain of C. boidinii (pmp20Delta strain). The His(6)-tagged CbPmp20 fusion protein was found to have glutathione peroxidase activity in vitro toward alkyl hydroperoxides and H(2)O(2). Catalytic activity and dimerization of His(6)-CbPmp20 depended on the only cysteine residue corresponding to Cys(53). The pmp20Delta strain was found to have lost growth ability on methanol as a carbon and energy source. The pmp20Delta growth defect was rescued by CbPmp20, but neither CbPmp20 lacking the peroxisome targeting signal type 1 sequence nor CbPmp20 haboring the C53S mutation retrieved the growth defect. Interestingly, the pmp20Delta strain had a more severe growth defect than the cta1Delta strain, which lacks catalase, another antioxidant enzyme within the peroxisome. During incubation of these strains in methanol medium, the cta1Delta strain accumulated H(2)O(2), whereas the pmp20Delta strain did not. Therefore, it is speculated to be the main function of CbPmp20 is to decompose reactive oxygen species generated at peroxisomal membrane surface, e.g. lipid hydroperoxides, rather than to decompose H(2)O(2). In addition, we detected a physiological level of reduced glutathione in peroxisomal fraction of C. boidinii. These results may indicate a physiological role for CbPmp20 as an antioxidant enzyme within peroxisomes rich in reactive oxygen species.

Amino Acid Sequence↗

PubMed2001

Interaction of hnRNP A2/B1 isoforms with telomeric ssDNA and the in vitro function.

Overexpression of heterogeneous nuclear ribonucleoprotein (hnRNP) A2/B1, especially of B1 has been reported as a useful marker to detect cancers in early stage, although the biological reason is not clear. A2/B1 proteins were previously reported to bind telomeric DNA repeats. Alternative splicing of A2/B1 gene produces abundant A2, less abundant B1, and testis-specific minor isoforms B0a and B0b. In this study, B1 and B0b that have the N-terminal 12 amino acid insertion were suggested to have higher affinities to telomeric single-stranded DNA (ssDNA) than A2 and B0a. Kinetic analyses using purified B1 and B0b indicated that they interact dynamically with a single array of telomeric repeats. Furthermore, functional assays demonstrated that B1 and B0b bind with telomeric repeats in a tandem fashion and protect them from a nuclease and promote telomerase activity. A2/B1 proteins, especially B1 and B0b, may function as telomeric ssDNA-binding proteins in cancer and reproductive cells.

Alternative Splicing↗

PubMed2001

Topographical analysis of p53 expression and DNA ploidy in early bronchial squamous cell carcinoma and preneoplastic lesions.

The significance of p53 mutations and DNA aneuploidy in carcinoma cells has been investigated on the basis of a multi-step development theory of carcinogenesis. It has, however, not been determined whether these alterations can be used as diagnostic markers for the early detection of bronchial squamous cell carcinoma (BSqCC). To address this problem, we topographically investigated p53 alterations and DNA aneuploidy in 24 X-ray-negative, early BSqCC patients with various preneoplastic lesions and in 25 non-carcinoma patients with preneoplastic lesions. Bronchial lesions (n=88) were morphologically classified as hyperplasia (HP, n=5), squamous metaplasia (SM, n=23), low-grade dysplasia (LGD, n=14), high-grade dysplasia (HGD, n=11), intraepithelial carcinoma including 'carcinoma in situ' (CIS) (IEC, n=15), and microinvasive carcinoma (MIC, n=20). Immunohistochemistry for the p53 protein and image cytometry for DNA ploidy detection were performed in serial sections of each lesion. Overexpression of p53 protein was detected in 36, 73, and 65% of the HGD, IEC, and MIC lesions, respectively. Aneuploid DNA profiles were found only in carcinoma lesions, 33% in IEC and 85% in MIC. The topographical analysis revealed two types of early BSqCCs, one with adjacent preneoplastic lesions (sequential type, n=8) and another without such lesions (de novo type, n=16). The p53 protein was frequently overexpressed in both types (sequential type, 79%; de novo type, 62%). In the sequential type, however, the p53 protein was overexpressed in HGD lesions that were directly adjacent to p53-overexpressing carcinoma lesions without exception. The present topographical study suggests that p53 mutations play an important role in the carcinogenesis of BSqCC and that p53-overexpressing HGD lesions in sequential types should be regarded as 'truly' preneoplastic lesions that actually develop into carcinomas. In addition, our study demonstrated that DNA aneuploidy might occur at times after p53 alteration with increasing frequency, as invasive growth begins. Such combination analysis of p53 immunohistochemistry and nuclear DNA ploidy in routine histology may contribute to estimates of malignant potential in preneoplastic and intraepithelial squamous lesions and provide additional information for early detection of BSqCC.

Aneuploidy↗

PubMed2001

Intranodal benign thyroid tissue: significance of HBME-1 in differentiation from metastatic papillary thyroid carcinoma.

The aim of this study was to determine the significance of HBME-1 immunostaining in the differentiation between intranodal benign thyroid tissue and metastatic papillary thyroid carcinoma in the lymph node. Immunohistochemically we examined normal-appearing intranodal thyroid tissue in four patients who did not show evidence of papillary carcinoma histologically or clinically. We also examined follicular-pattern-predominant papillary carcinoma with metastatic foci in the lymph nodes. Normal-appearing intranodal thyroid tissue and normal thyroid showed no immunopositivity for HBME-1. In contrast, all papillary carcinomas in both the lymph nodes and thyroid demonstrated strong positivity for HBME-1. HBME-1 was predominantly positive for the luminal surface of the tumor cells. The immunopositivity of the cuboidal and low columnar carcinoma cells was more intensive than that of the flat-shaped cells in the lymph nodes and thyroid. The results probably indicate that HBME-1 immunostaining is helpful in distinguishing between intranodal benign thyroid tissue and metastatic papillary carcinoma in lymph nodes. We emphasize that the HBME-1 reactivity should be evaluated in connection with the histological findings, and that positive and negative controls stained in parallel are necessary.

Aged↗

PubMed2001

Abnormal venous structures in salivary gland tumors: vasculature characteristics of pleomorphic adenoma.

To clarify the diagnostic significance of abnormal venous structures present in salivary gland tumors, we examined 21 pleomorphic adenomas, 14 Warthin tumors, 1 oncocytic adenoma, 3 myoepitheliomas, 7 basal cell adenomas, 5 mucoepidermoid carcinomas, and 6 adenoid cystic carcinomas. Verhoeffvan Gieson staining was carried out and the morphology of the veins within the tumors was observed microscopically. Branching veins, thickened intima of the veins, discontinuous elastic membrane and multilayered elastic membrane were seen in 71.4%, 76.2%, 47.6% and 85.7% of pleomorphic adenomas, respectively, and were abundant and easily found in most cases. The abnormal venous structures were also found in other salivary gland tumors examined, but they were few in number and lacked variety. Elastic fibers extending radially into the surrounding stroma were seen in 66.7% of pleomorphic adenomas, and were not seen in other salivary gland tumors. Our results showed that a variety of abnormal venous structures are more abundant and more easily found in pleomorphic adenoma compared with other salivary gland tumors, and, in particular, that perivascular radiating elastic fibers are characteristic of pleomorphic adenoma. We emphasize that the presence of perivascular radiating elastic fibers may be helpful in diagnosing pleomorphic adenoma in small biopsy specimens.

Adenoma, Pleomorphic↗

PubMed2001

Endolymphatic sac tumor associated with a von Hippel-Lindau disease patient: an immunohistochemical study.

The authors report a case of endolymphatic sac tumor (ELST) associated with Von Hippel-Lindau disease (VHL). A 20-year-old female VHL patient received a resection of a cerebellar hemangioblastoma 3 years ago and she had a co-existing of left petrous tumor. The petrous tumor showed a remarkable progression in 3 years and was resected subtotally. Histologically, the resected petrous tumor showed a papillary structure containing cuboidal or columnar cells with fibrous stroma and numerous microvessels and destructed temporal bone, all of which are consistent with ELST. We studied the expression of various kinds of cytokeratins (CKs) immunohistochemically and found distinct expression of CKs (CAM 5.2, 34betaE-12, CK7, CK8 and CK19), but not for CK10/13 or CK20. Vascular endothelial growth factor and neuron specific enolase showed strong immunoreactivity in the tumor cells. CD34 also had weak expression. Ki-67 antigen (MIB-1) immunoreactivity was found in focal areas, and the labeling index in the highest-density area was 48.9%. These findings suggest that vascular endothelial growth factor overexpression is an important factor for angiogenesis in ELST, much like other VHL-associated tumors, and that ELST may have a more highly aggressive component than the low-grade malignancy noted in previous reports.

Adult↗

PubMed2001

TP53 deleted cells in de novo glioblastomas using fluorescence in situ hybridization.

Glioblastoma (GBM) has been known to have two distinct genetic pathways of tumorigenesis. Secondary GBM shows frequent TP53 mutation, but de novo (primary) GBM is usually independent of TP53 alteration. However, the subpopulation of TP53 altered cells in the latter tumor is obscure. In order to assess TP53 deleted cells in de novo GBM quantitatively, we performed dual color fluorescence in situ hybridization (FISH) for TP53 and centromere 17 in nine cases of de novo GBM with frozen surgical materials. Single TP53 signal cells indicating TP53 deletion were recognized in 8.7-35.6% (mean, 21.3%) among the nine cases. In addition, immunohistochemistry was performed for the Ki-67 antigen (MIB-1) and p53 protein in all nine cases. Labeling indices (LI) of MIB-1 ranged from 2.8 to 46.9% (mean, 20.8%). Between the group with the more dense subpopulation of TP53 deleted cells (15% or more) by FISH and the group with less subpopulation than the former, these LI of MIB-1 demonstrated statistically significant difference (respective means, 28.2% and 6.1%; P < 0.05). Conversely, LI of p53 protein shown to be 0-50.9% (mean, 24.9%) had no correlation with the subpopulation of TP53 deleted cells by FISH. Four cases who had higher LI of p53 protein (mean, 39.7%) than the subpopulation of TP53 deleted cells (mean, 12.7%), respectively, indicated the presence of many p53 protein immunoreactive cells without TP53 deletion. These results suggest that: (i) de novo GBM also has subpopulation of TP53 deleted cells; (ii) TP53 alteration, which may not be a major event, participates in cell proliferation of de novo GBM; and (iii) de novo GBM tends to have accumulation of wild-type p53 protein.

Adult↗

PubMed2001

Bizarre parosteal osteochondromatous proliferation (Nora's lesion) of the foot.

A 22-year-old man presented with a growing lump on the fifth metatarsal of the right foot. Radiographically, the lesion was a calcified mass stuck on to the bone. The T2-weighted magnetic resonance images showed heterogeneity in intensity. A tumor was suspected and an excisional biopsy was done. The lesion was composed of a cartilaginous cap and bone tissue. Histological examination revealed characteristic features of bizarre parosteal osteochondromatous proliferation (BPOP), such as hypercellularity, a blue tinctorial quality in the osteocartilaginous interfaces, and a scattering of binucleated or bizarre enlarged chondrocytes. Immunohistochemically, basic fibroblast growth factor was expressed in nearly all chondrocytes within the cartilaginous cap, while vascular endothelial growth factor was expressed only in enlarged chondrocytes near the osteocartilaginous interfaces. Reverse transcription-polymerase chain reaction detected chondromodulin-I transcripts in the tissue of the cartilaginous cap. These findings indicate that the processes occurring in BPOP are similar to those occurring in endochondral ossification in the growth plate, and they support the concept that BPOP is a reparative process. BPOP is a rare tumorous lesion of the bone and is occasionally confused with other benign or malignant conditions. Thus, it is important to consider the clinical, radiographical and the gross histological features of the lesion when making a diagnosis.

Adult↗

PubMed2001

Combined therapeutic approach of intra-arterial thrombolysis and carotid endarterectomy in selected patients with acute thrombotic carotid occlusion.

PURPOSE: The feasibility and clinical outcome of intra-arterial thrombolysis followed by carotid endarterectomy (CEA) for acute thrombotic occlusion of the internal carotid artery (ICA) were evaluated. METHODS: Intra-arterial thrombolysis and CEA were performed in four patients with acute thrombotic ICA occlusion. Computed tomography scans, cerebral angiograms, and the severity of carotid plaques were examined, and the patients' clinical outcome was evaluated. RESULTS: All 4 patients had severe hemiparesis; 3 patients were alert, and 1 patient was lethargic at the time of hospital admission. New lesions were not shown by means of the initial computed tomography scan. ICA occlusion was indicated in all four patients by means of cerebral angiograms; in three patients, middle cerebral artery occlusion was noted. Collateral circulation was manifested in all patients. Partial recanalization of the occluded ICA was obtained in all patients. Two patients with severe residual ICA stenosis underwent an emergency CEA soon after thrombolysis; the other two patients were treated by means of CEA in the subacute or chromic stage. Plaque rupture and intraplaque hemorrhage were seen in all four patients. All four patients recovered completely, and restenosis of the ICA was not shown by means of follow-up angiograms. CONCLUSION: Intra-arterial thrombolysis followed by CEA may be an effective therapeutic approach for treating acute thrombotic ICA occlusion. The optimal timing of CEA remains controversial.

Acute Disease↗

PubMed2001

Peroxisomal catalase in the methylotrophic yeast Candida boidinii: transport efficiency and metabolic significance.

In this study we cloned CTA1, the gene encoding peroxisomal catalase, from the methylotrophic yeast Candida boidinii and studied targeting of the gene product, Cta1p, into peroxisomes by using green fluorescent protein (GFP) fusion proteins. A strain from which CTA1 was deleted (cta1Delta strain) showed marked growth inhibition when it was grown on the peroxisome-inducing carbon sources methanol, oleate, and D-alanine, indicating that peroxisomal catalase plays an important nonspecific role in peroxisomal metabolism. Cta1p carries a peroxisomal targeting signal type 1 (PTS1) motif, -NKF, in its carboxyl terminus. Using GFP fusion proteins, we found that (i) Cta1p is transported to peroxisomes via its PTS1 motif, -NKF; (ii) peroxisomal localization is necessary for Cta1p to function physiologically; and (iii) Cta1p is bimodally distributed between the cytosol and peroxisomes in methanol-grown cells but is localized exclusively in peroxisomes in oleate- and D-alanine-grown cells. In contrast, the fusion protein GFP-AKL (GFP fused to another typical PTS1 sequence, -AKL), in the context of CbPmp20 and D-amino acid oxidase, was found to localize exclusively in peroxisomes. A yeast two-hybrid system analysis suggested that the low transport efficiency of the -NKF sequence is due to a level of interaction between the -NKF sequence and the PTS1 receptor that is lower than the level of interaction with the AKL sequence. Furthermore, GFP-Cta1pDeltankf coexpressed with Cta1p was successfully localized in peroxisomes, suggesting that the oligomer was formed prior to peroxisome import and that it is not necessary for all four subunits to possess a PTS motif. Since the main physiological function of catalase is degradation of H2O2, suboptimal efficiency of catalase import may confer an evolutionary advantage. We suggest that the PTS1 sequence, which is found in peroxisomal catalases, has evolved in such a way as to give a higher priority for peroxisomal transport to peroxisomal enzymes other than to catalases (e.g., oxidases), which require a higher level of peroxisomal transport efficiency.

Amino Acid Motifs↗

PubMed2000

Cadmium and platinum suppression of erythropoietin production in cell culture: clinical implications.

Both toxic exposure to cadmium and cancer therapy with cisplatin (CDDP) can induce anemia in patients owing to the insufficient production of erythropoietin (EPO). Therefore, the effects of cadmium chloride (Cd) and CDDP in the Hep3B human hepatoma cell line, which up-regulates EPO expression in response to hypoxia and cobalt (Co), were investigated. The induction of binding activity of the HIF-1 transcription factor and EPO mRNA expression and protein production were suppressed by Cd and CDDP in a dose-dependent manner with no apparent cell damage. Mercuric chloride also suppressed hypoxia- and Co-induced EPO production, mRNA expression, and HIF-1 binding in a manner similar to Cd and CDDP, whereas zinc chloride suppressed Co-induced EPO production, mRNA expression, and HIF-1 binding but did not affect hypoxia induction or that observed after simultaneous exposure to hypoxia and Co. In contrast, lead and tin salts had no effect on HIF-1 activation or EPO expression. These results indicate that Cd and CDDP have a strong and specific inhibitory effect on hypoxia- and Co-induced signaling and EPO induction in hepatic cells. It is likely that these agents cause anemia by directly impacting EPO production in the kidney. (Blood. 2000;96:3743-3747)

Cadmium↗

PubMed2000

Testis- and developmental stage-specific expression of hnRNP A2/B1 splicing isoforms, B0a/b.

Heterogeneous nuclear ribonucleoproteins (hnRNPs) A2 and B1 are abundant nuclear proteins that bind to nascent RNAs synthesized by RNA polymerase II. Previously we had found that the splicing isoforms hnRNP B0a/b, from which the ninth exon of the A2/B1 gene is excluded, are abundantly expressed in testis. We postulated that B0a/b are testis-specific isoforms, and investigated the expression of A2/B1 and B0a/b in rat tissues and in postnatal development of rat testes using RNase protection assay, immunoblotting, and immunohistochemistry. We found that hnRNP B0a/b mRNAs are expressed in several tissues but that the testis alone expresses B0a/b proteins. A sequential study using neonatal rat testes demonstrated that B0a/b mRNAs are produced after 17 days of age, but not translated until 4 weeks of age when round spermatids appear in addition to spermatogonia and spermatocytes. Immunohistochemically, hnRNP A2/B1 isoforms are expressed during spermatogenesis from spermatogonia through round spermatids, whereas the expression of A1 is restricted to spermatogonia. This expression pattern in the rat testis is maintained from birth through adulthood. These results suggest that the expression of the hnRNP A2/B1 gene is partly regulated by a testis-specific post-transcriptional mechanism, and that the products of the A2/B1 gene, especially hnRNP B0a/b, are involved in spermatogenesis.

Animals↗

PubMed2000

Molecular characterization of a mouse heterogeneous nuclear ribonucleoprotein D-like protein JKTBP and its tissue-specific expression.

The human DNA- and RNA-binding protein JKTBP is a new member of heterogeneous nuclear ribonucleoproteins (hnRNPs) that are involved in mRNA biogenesis. We cloned and characterized a mouse homolog and studied its expression in mouse tissues. The cDNA encoded a 301-residue polypeptide. There is only a single amino acid difference between the mouse and human sequences. Northern blotting indicated ubiquitous but varied expressions of approximately 1.4 and 2.8kb mRNAs in various tissues. Immunoblotting indicated that the amounts of protein of about 38kDa were higher in the brain and testis than in other tissues. An additional protein of about 53kDa was found in the brain and testis. Germ cell-deficient W/W(v) mutant mice and aged mice had the reduced amounts of JKTBP in the testes. Immunohistochemical staining indicated cell type-specific expression of JKTBP in tissues: neurons and spermatocytes displayed strong signal intensities. The signals were confined to the nucleus. The amount of 38kDa JKTBP was estimated to be approximately 1.3x10(7) molecules per HL-60 cell. These results indicate that JKTBP is an abundant, highly conserved nuclear protein.

Animals↗