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T Fujiwara

Publications and source records attributed to T Fujiwara.

At least 91 records · Page 5Linked to original sources
PubMed2001

Efforts toward creating unnatural base pairs for an expanded genetic code.

A series of unnatural base pairs was designed and examined for the expansion of the genetic alphabet and for a better understanding of the mechanism of nucleic acid biosyntheses. To improve the shape complementarity of the previously developed unnatural base pairs, 2-amino-6-(N,N-dimethylamino)purine (x)--pyridon-2-one (y) and 2-amino-6-(2-thienyl)purine (s)--y, the pyrimidine analogue, y, was replaced by a five-member ring, 4-imidazolin-2-one (z), and the s-z pairing in replication was examined. Unnatural bases based on the five-member ring were also applied to the development of non-hydrogen-bonded base pairs.

Base Pairing↗
PubMed2001

Etiology and pathogenesis of aponeurotic blepharoptosis.

How and why aponeurotic blepharoptosis develops was investigated in terms of the relationship between the levator aponeurosis and Mueller's muscle functioning as the muscle spindle of the levator muscle. A total of 200 consecutive patients with moderate to severe acquired blepharoptosis completed questionnaires regarding their history of physical irritations to the eyelids, and intraoperative conditions of the levator aponeurosis and Mueller's muscle were evaluated. Several kinds of physical irritations to the eyelids were reported, such as habitual rubbing of the eyelids, contact lens usage, cataract surgery, and continuous rubbing of the eyelids while crying all night. The two main findings for aponeurosis were that it was disinserted from the tarsus, resulting in a large amount of play between the aponeurosis and the tarsus, and that the aponeurosis and Mueller's muscle were attenuated and elongated. The authors believe that rubbing may have caused disinsertion as well as attenuation and elongation of the aponeurosis, which result in transmission failures between the levator muscle and the tarsus as well as between the levator muscle and the mechanoreceptor of Mueller's muscle, leading to clinical blepharoptosis.

Adult↗
PubMed2001

Pleuropericarditis and disseminated intravascular coagulation in ulcerative colitis.

We report a 30-year-old woman with pleuropericarditis, cardiac tamponade, and disseminated intravascular coagulation complicating active ulcerative colitis (UC). Other autoimmune diseases were not present. She responded to pulsed steroid therapy and anticoagulant with resolution of the complication and UC. We reviewed the literature and found 27 cases of pleuropericarditis associated with idiopathic inflammatory bowel disease (IBD). It has been reported that pleuropericarditis associated with IBD responds well to nonsteroidal antiinflammatory drugs, as well as steroids. The causes of cardiac involvement in IBD remain unclear, but the pleuropericarditis must be recognized as a potential extraintestinal manifestation of IBD.

Adult↗
PubMed2001

Aldosterone synthase gene (CYP11B2) C-334T polymorphism, ambulatory blood pressure and nocturnal decline in blood pressure in the general Japanese population: the Ohasama Study.

OBJECTIVE: The C-344T polymorphism in the 5'-flanking region of the aldosterone synthase (CYP11B2) gene has been suggested to be associated with hypertension and disturbed circadian blood pressure (BP) rhythm through its effect on aldosterone synthesis. However, previous findings on this topic have been inconsistent. DESIGN: A cross-sectional study. SUBJECTS AND METHODS: We investigated the CYP11B2 C-344T genotype in 802 subjects, aged 40 and over, in a Japanese community, who gave written informed consent and were monitored for 24 h ambulatory BP. RESULTS: The frequencies of the CC, CT, and TT genotypes in these Japanese subjects were 0.14, 0.44, and 0.42, showing a higher frequency of the T allele (0.64) than in Caucasians. Although there was no significant difference in 24 h ambulatory BP levels among the genotypes, the nocturnal decline in BP was significantly greater in the CC homozygous subjects than in other subjects (P = 0.0065 for systolic and P = 0.031 for diastolic decline in nocturnal BP). Detailed analyses demonstrated that this association was significant only in aged (60 years and over) or male subjects. The prevalence of previous cardiovascular disease was significantly less in these subjects with the CC genotype than in those with the TC and TT genotypes, although age, body mass index, male gender, smoking, use of alcohol and antihypertensive medication did not differ among the three genotypes. There was no significant difference among the three genotypes in biochemical and hormonal parameters. CONCLUSION: Although the C-344 T polymorphism of CYP11B2 did not directly influence the level of 24 h BP, the CC genotype was associated with decreased nocturnal BP in elderly or male Japanese. Since prevalence of previous cardiovascular disease was significantly less in homozygous CC subjects, greater nocturnal BP decline in this genotype appears to be beneficial in the circadian BP rhythm.

Aged↗
PubMed2001

All-trans-retinoic acid enhances the effect of adenovirus-mediated wild-type p53 gene transfer in head and neck squamous cell carcinoma.

OBJECTIVES: Adenovirus-mediated p53 (AdCMVp53) gene therapy for cancer is currently undergoing phase III clinical trials. One problematic aspect of this therapy is that the current protocols result in low transduction of the therapeutic virus in vivo. To search new modalities that can enhance the effect of AdCMVp53 gene therapy, we focused on retinoids. METHODS: To study the effect of ATRA in combination with AdCMVp53 gene therapy, we pretreated head and neck squamous cell carcinoma (HNSCC) cells for 72 hours with a low-dose All-trans-retinoic acid (ATRA) (10-7 M-10-8 M) which will not affect the in vitro cell growth, and then infected the cells with low MOI (30MOI) AdCMVp53. In vitro cell proliferation assays, cell cycle assays were performed. Expression of p53 and p53-related gene products, BAX and p21, were examined. RESULTS: The combined treatment with ATRA and Ad-p53 suppressed cell growth and induced apoptosis significantly more than AdCMVp53 treatment alone (P <.05). p53 expression significantly increased more after the combined treatment than after either treatment alone, at both the transcription and protein levels. In addition, increased expression of p21 and BAX, which are downstream gene products of p53, was observed in the combination. ATRA also enhanced the expression of green fluorescent protein (GFP) transduced by an adenovirus-cytomegalovirus (CMV)-GFP vector suggesting ATRA enhances adenovirus-CMV-promoted vectors through transcription. CONCLUSIONS: Our results indicate that ATRA enhances AdCMVp53 expression through transcriptional mechanisms and can synergistically induce apoptosis in HNSCC cells. ATRA has a potential to enhance the effect of adenovirus-mediated p53 gene therapy for HNSCC.

Adenoviridae↗
PubMed2001

Predictive values of automated blood pressure measurement: what can we learn from the Japanese population - the Ohasama study.

BACKGROUND: Measurements of ambulatory blood pressure (ABP) and of home blood pressure (HBP) as an adjunct to casual/clinic blood pressure (CBP) measurements are currently widely used for the diagnosis and treatment of hypertension. We have monitored a rural cohort of people from the population of Ohasama, Japan, with respect to their prognosis and have previously reported that ABP and HBP are superior to CBP for the prediction of cardiovascular mortality. One reason that CBP is a poor predictor of prognosis is that it incorporates several biases, including the white-coat effect. METHODS AND RESULTS: We examined the prognostic significance of white-coat hypertension for mortality and found that the relative hazard for the overall mortality of patients with white-coat hypertension was significantly lower than that for true hypertension. Short-term blood pressure variability has recently attracted attention as a cause of target-organ damage and cardiovascular complications. Our results confirmed that short-term blood pressure variability (as measured every 30 min) was independently associated with cardiovascular mortality. In addition, research has recently focused on isolated systolic hypertension and pulse pressure as independent risk factors for poor cardiovascular prognosis. The Ohasama study also clearly demonstrated that isolated systolic hypertension and increased pulse pressure, as assessed by HBP, were associated with an increase in the risk of cardiovascular mortality. Circadian blood pressure variation is characterized by a diurnal elevation and a nocturnal decline in blood pressure. We therefore compared morbidity from stroke between dippers (subjects who show an ordinal nocturnal dipping of blood pressure) and non-dippers (those with a diminished nocturnal dipping or nocturnal elevation of blood pressure [inverted dippers]) in the Ohasama study. The incidence of stroke increased with an increased length of observation in dippers using antihypertensive medication but not in non-dippers using antihypertensive medication. In contrast, the relative hazard for mortality increased in non-dippers and inverted dippers. These results suggest a cause-and-effect relationship for both dippers and non-dippers. CONCLUSION: The Ohasama study showed that the level and variability of hypertension as assessed by ABP and HBP are independent predictors of cardiovascular mortality. It also demonstrated an independent association between the prognosis of hypertension and each component of ABP and HBP, indicating the prognostic significance of these blood pressure measurements.

Bias↗
PubMed2001

Heterogeneity of p53 mutational status in intramucosal carcinoma of the colorectum.

The aim of this study was to elucidate whether or not p53 genetic heterogeneity would occur while colorectal carcinoma was limited to the mucosa. Eight cases of endoscopically resected colorectal intramucosal carcinomas were analyzed to determine the p53 gene sequence (exons 5 to 8). Six out of 8 cases showed p53 gene mutations, and in all of them, the mutational status was heterogeneous. In 4 cases, mutated codons were heterogeneous as well. These data indicate that p53 gene alterations in colorectal carcinomas occur and diverge at the stage of intramucosal carcinoma, supporting our previously proposed hypothesis that colorectal carcinomas can be composed of various subclones as regards p53 gene mutation, while the carcinoma is limited to the mucosa, and one of these subclones commences invasion to the submucosa after clonal selection, thus generating a monoclonal invasive carcinoma.

Carcinoma↗
PubMed2001

Purification, characterization, and genetic analysis of Cu-containing dissimilatory nitrite reductase from a denitrifying halophilic archaeon, Haloarcula marismortui.

Cu-containing dissimilatory nitrite reductase (CuNiR) was purified from denitrifying cells of a halophilic archaeon, Haloarcula marismortui. The purified CuNiR appeared blue in the oxidized state, possessing absorption peaks at 600 and 465 nm in the visible region. Electron paramagnetic resonance spectroscopy suggested the presence of type 1 Cu (g(II) = 2.232; A(II) = 4.4 mT) and type 2 Cu centers (g(II) = 2.304; A(II) = 13.3 mT) in the enzyme. The enzyme contained two subunits, whose apparent molecular masses were 46 and 42 kDa, according to sodium dodecyl sulfate-polyacrylamide gel electrophoresis. N-terminal amino acid sequence analysis indicated that the two subunits were identical, except that the 46-kDa subunit was 16 amino acid residues longer than the 42-kDa subunit in the N-terminal region. A nirK gene encoding the CuNiR was cloned and sequenced, and the deduced amino acid sequence with a residual length of 361 amino acids was homologous (30 to 41%) with bacterial counterparts. Cu-liganding residues His-133, Cys-174, His-182, and Met-187 (for type 1 Cu) and His-138, His-173, and His-332 (for type 2 Cu) were conserved in the enzyme. As generally observed in the halobacterial enzymes, the enzymatic activity of the purified CuNiR was enhanced during increasing salt concentration and reached its maximum in the presence of 2 M NaCl with the value of 960 microM NO(2)(-) x min(-1) x mg(-1).

Absorption↗
PubMed2001

Dynamic localization and function of Bni1p at the sites of directed growth in Saccharomyces cerevisiae.

Formin homology (FH) proteins are implicated in cell polarization and cytokinesis through actin organization. There are two FH proteins in the yeast Saccharomyces cerevisiae, Bni1p and Bnr1p. Bni1p physically interacts with Rho family small G proteins (Rho1p and Cdc42p), actin, two actin-binding proteins (profilin and Bud6p), and a polarity protein (Spa2p). Here we analyzed the in vivo localization of Bni1p by using a time-lapse imaging system and investigated the regulatory mechanisms of Bni1p localization and function in relation to these interacting proteins. Bni1p fused with green fluorescent protein localized to the sites of cell growth throughout the cell cycle. In a small-budded cell, Bni1p moved along the bud cortex. This dynamic localization of Bni1p coincided with the apparent site of bud growth. A bni1-disrupted cell showed a defect in directed growth to the pre-bud site and to the bud tip (apical growth), causing its abnormally spherical cell shape and thick bud neck. Bni1p localization at the bud tips was absolutely dependent on Cdc42p, largely dependent on Spa2p and actin filaments, and partly dependent on Bud6p, but scarcely dependent on polarized cortical actin patches or Rho1p. These results indicate that Bni1p regulates polarized growth within the bud through its unique and dynamic pattern of localization, dependent on multiple factors, including Cdc42p, Spa2p, Bud6p, and the actin cytoskeleton.

Actins↗
PubMed2001

Contributions of three glycosyltransferases to sucrose-dependent adherence of Streptococcus mutans.

Streptococcus mutans produces 3 types of glucosyltransferase (GTF), whose cooperative action is considered to be essential for its cellular adherence to the tooth surface. However, the precise mechanisms for synthesizing adhesive glucans and the specific roles of each GTF in cellular adherence to smooth surfaces have not been elucidated. In the present study, seven types of isogenic mutants of S. mutans MT8148 lacking GTFB, GTFC, and/or GTFD activities were constructed by inactivation of the genes encoding GTFB, GTFC, and/or GTFD. Furthermore, recombinant GTFB, GTFC, and GTFD were prepared from Escherichia coli cells harboring recombinant plasmids containing each of the gtf genes. Using these GTF-deficient mutants and rGTFs, we reconstituted sucrose-dependent adherence of S. mutans resting cells and examined the role of each GTF in vitro. The highest level of sucrose-dependent adherence was found at the ratio of 20 rGTFB:1 rGTFC:4 rGTFD in both the resting cells of GTF-deficient mutants and insoluble glucan synthesized by rGTFs. Moreover, when rGTFC and rGTFD were both present at concentrations of 1.5 mU and 6 mU, respectively, the insoluble glucan synthesized from sucrose by the rGTFs showed a high level of adhesiveness to smooth surfaces, even without rGTFB. These results suggest that the presence of all three GTFs at the optimum ratio is necessary for sucrose-dependent adherence of S. mutans, and that GTFC and GTFD may play significant roles in the synthesis of adhesive and insoluble glucan from sucrose.

Bacterial Adhesion↗
PubMed2001

Demonstration of angiogenin in human endometrium and its enhanced expression in endometrial tissues in the secretory phase and the decidua.

Angiogenesis is thought to be crucial for normal physiology of the endometrium, where dynamic vascular remodeling occurs during the menstrual cycle and pregnancy. We investigated the presence of angiogenin, a potent inducer of angiogenesis, and the regulatory mechanisms of its production in the human endometrium. Western blot analysis demonstrated that angiogenin protein expression increased by 3- to 4-fold in the endometrium in the mid and late secretory phases and in early gestation relative to that during the proliferative phase. Quantitative mRNA analysis showed the similar tendency in the expression of angiogenin mRNA in the endometrium, with the highest levels observed in the mid and late secretory phases and early gestation. An immunohistochemical study showed that angiogenin was expressed in both stromal cells and epithelial cells, with indistinguishable intensity between these cells regardless of phases of the menstrual cycle. In support of the Western blot analysis, the intensity of staining appeared to be highest in the mid to late secretory phases relative to other phases. Consistent with these in vivo results, decidualized cultured stromal cells, after treatment with progesterone or progesterone plus E2, exhibited the capacity to secrete significantly increased amounts of angiogenin compared with untreated or E2 alone-treated control group. Both the treatment with (Bu)2cAMP and hypoxic conditions stimulated angiogenin secretion by stromal cells. For isolated epithelial cells, hypoxia stimulated angiogenin secretion, whereas (Bu)2cAMP had no appreciable effect. In summary, we demonstrated the presence of angiogenin in human endometrium and its possible local regulatory factors, such as progesterone, cAMP, and hypoxia. These findings along with its enhanced expression in the endometrium in the secretory phase and in decidual tissues raise the possibility that angiogenin may play a role in establishing pregnancy.

Blotting, Western↗
PubMed2001

Dynamics of inhibin subunit and follistatin mRNA during development of normal and polycystic ovary syndrome follicles.

To further explore the developmental dynamics and possible roles of inhibin, activin, and follistatin in the development of human antral follicles as well as the relationship between mRNA and protein levels of these hormones within follicles, quantitative competitive RT-PCR assays were established to determine mRNA levels for the inhibin/activin subunits and both follistatin splice variants. Granulosa cell RNA was obtained by transvaginally aspirating follicles (6-23 mm) from carefully characterized normal women at different times of the follicular phase. alpha- and beta(A)-subunit mRNA levels increased significantly with follicle diameter (r = 0.56; P < 0.01 and r = 0.45; P < 0.05, respectively) and follicle maturity (r = 0.65; P < 0.001 and r = 0.58; P < 0.01, respectively), but beta(B) mRNA levels, which were at least 10-fold lower than levels of the other subunits, showed no relationship to size or maturity. Both follistatin 315 and 288 transcripts were detected in granulosa cells, but neither follistatin transcript varied significantly across the range of follicle sizes analyzed. In addition, granulosa cells contained three follistatin 315 mRNA transcripts for each follistatin 288 transcript, and the follistatin 315/288 ratio did not vary with follicle size. alpha-Subunit mRNA levels were positively associated with dimeric inhibin A protein in human follicular fluid from the same follicle aspirates (r = 0.71; P < 0.001). Similarly, beta(A)-subunit mRNA was associated with inhibin A (r = 0.59; P < 0.01), and beta(B) mRNA was associated with inhibin B (r = 0.67; P < 0.005) in these samples. Thus, the increase in inhibin subunit transcription and protein synthesis with follicle size suggests that inhibin biosynthesis might be important for continued development of the dominant follicle. To explore this hypothesis further, we compared mRNA levels for each of these transcripts in follicles obtained from six polycystic ovary syndrome patients (eight follicles) and compared the results to those from a group (n = 5) of normal follicles matched for mean diameter. Comparisons were also performed for a subset of polycystic ovary syndrome follicles (n = 5) matched for diameter and size range with the normal group. alpha-Subunit mRNA levels were 16-fold lower in both polycystic ovary syndrome follicle groups relative to size-matched normal follicles (P < 0.02), whereas beta(A)-subunit mRNA was significantly lower only when all polycystic ovary syndrome follicles were compared. beta(B)-Subunit and follistatin mRNA levels and the follistatin 315/288 ratio were not statistically different for any group. These results suggest that insufficient production of inhibin alpha and possibly beta(A)-subunits, but not follistatin, is associated with follicular arrest in polycystic ovary syndrome follicles.

Actins↗
PubMed2001

Combination of N-methyl-1-deoxynojirimycin and ischemic preconditioning markedly reduces the size of myocardial infarcts in rabbits.

N-methyl-1-deoxynojirimycin (NMDN), an a-glucosidase inhibitor, reduces myocardial infarct size by reducing the glycogenolytic rate through inhibition of the alpha-1,6-glucosidase of glycogen-debranching enzyme in the heart, in addition to possessing an antihyperglycemic action by blocking alpha-1,4-glucosidase in the intestine. Ischemic preconditioning (PC), which markedly reduces the size of the myocardial infarct, is known to reduce the activity of phosphorylase and reduce the glycogenolytic rate. Therefore, it was hypothesized that a combination of pharmacological inhibition of glycogenolysis by an alpha-1,6-glucosidase inhibitor, NMDN, and PC could markedly reduce myocardial infarct size more than NMDN or PC alone. Japanese white rabbits without collateral circulation were subjected to a 30-min coronary occlusion followed by 48-h reperfusion. The infarct sizes as a percentage of area at risk were significantly reduced by pre-ischemic treatment with either 100mg/kg of NMDN or PC of 5 min ischemia and 5 min reperfusion alone (15.9+/-2.0%, n=8, and 10.3+/-1.2%, n=8, respectively) as compared with the control (43.9+/-2.2%, n=8). However, the combination of 100mg/kg of NMDN and PC significantly reduced the infarct size (4.9+/-1.2, n=8) compared with NMDN or PC alone. Another 40 rabbits, also given 100mg of NMDN, PC, NMDN+PC or saline before ischemia (n=10 in each group), were killed for biochemical analysis after 30 min of ischemia. NMDN and PC preserved the glycogen content and attenuated the lactate accumulation, respectively, as compared with the control. However, the combination of NMDN and PC preserved significantly more glycogen and significantly reduced lactate accumulation than either NMDN or PC alone. The combination of NMDN and PC markedly reduced the myocardial infarct size more than either process alone. The marked preservation of glycogen and marked attenuation of lactate accumulation by the combination of NMDN and PC suggest that the mechanism for this effect of NMDN+PC is related to the inhibition of glycogenolysis.

1-Deoxynojirimycin↗
PubMed2001

Apoptosis, rather than oncosis, is the predominant mode of spontaneous death of isolated adult rat cardiac myocytes in culture.

A number of isolated adult cardiomyocytes dies within a few days of culture and the mode of death has recently been suggested to be apoptosis, based on its association with the appearance of DNA fragmentation. However, morphological evidence is still lacking and precise analysis, including quantification, has not been performed. Adult rat ventricular cardiomyocytes isolated by enzymatic dissociation were incubated for 7 days in a serum-free medium (the rapid attachment model) and after various incubation periods, both attached and floating cells were counted and classified based on combined criteria of morphology and membrane permeability (dye exclusion): type 1, rod cells with intact membranes; type 2, non-rod cells with intact membranes; and type 3, non-rod cells with ruptured membranes. The number of both rod-shaped and dye-excluding cells decreased with the incubation period. After 7 days culture, the number of residual cells decreased to 12% of the initial value. Electron microscopy identified type 1 cells as viable, type 2 cells as viable or apoptotic, and type 3 as undergoing oncosis (primary necrosis) or secondary post-apoptotic necrosis. Ultrastructural morphometry revealed that oncotic cell death occurred predominantly during the early phase of culture whereas the more abundant apoptotic cell death occurred throughout the culture period. In conclusion, although both apoptotic and oncotic death occur in the natural course of adult rat cardiomyocytes in short-term culture, apoptosis is more predominant. Because of the high incidence of spontaneous cell death predominantly via apoptosis, this information is important for the interpretation of studies using this cell type in culture.

Animals↗
PubMed2001

Caspase-dependent and serine protease-dependent DNA fragmentation of myocytes in the ischemia-reperfused rabbit heart: these inhibitors do not reduce infarct size.

Some infarcted myocytes undergo caspase-dependent DNA fragmentation, but serine protease-dependent DNA fragmentation may also be involved. There is controversy regarding whether caspase inhibitors can reduce infarct size, so the present study investigated whether serine protease inhibitor can reduce the DNA fragmentation of infarcted myocytes and whether serine protease or caspase inhibitors attenuates myocardial infarct size in Japanese white rabbits without collateral circulation. Rabbits were subjected to 30-min coronary occlusion followed by 48-h reperfusion. A vehicle (dimethylsulfoxide, control group, n=8) or Z-Val-Ala-Asp(Ome)-CH2F (ZVAD-fmk, a caspase inhibitor, ZVAD group, 0.8 mg/kg iv at 20 min before coronary occlusion and 0.8 mg/kg at 90 min after reperfusion, n=8) or 3,4-dichloroisocoumarin (DCI, a serine protease inhibitor, 2 mg/kg iv at 20 min before coronary occlusion, DCI group, n=8) was administered. Animals were killed at 48h after reperfusion for the detection of myocardial infarct size and at 4h after reperfusion for the detection of dUTP nick end-labeling (TUNEL)-positive myocytes, the electrophoretic pattern of DNA fragmentation and ultrastructural analysis. The left ventricle (LV) was excised and sliced. The myocardial infarct size as a percentage of the area at risk was assessed by triphenyltetrazolium chloride staining. DNA fragmentation was assessed by in situ TUNEL at the light microscopic level. ZVAD and DCI significantly reduced the mean blood pressure during reperfusion without affecting heart rate. There was no significant difference in the % area at risk (AAR) of LV among the 3 groups (control: 26.3+/-3.0%; ZVAD: 25.6+/-2.6%; DCI: 25.6+/-2.0%). The % infarct size as a percentage of the AAR in the ZVAD group (41.3+/-4.5%) and the DCI group (50.4+/-3.8%) was not significantly different from the control group (43.5+/-4.5%). However, the percent DNA fragmentation in the infarcted area in the ZVAD (3.5+/-0.8%) and DCI groups (4.2+/-0.9%) was significantly reduced compared with the control group (10.7+/-1.9%). The DNA ladder pattern observed in the control group was attenuated in both the ZVAD and DCI groups. There was no difference in electron microscopic changes among the 3 groups. Serine protease-dependent DNA fragmentation is present in infarcted myocytes, in addition to caspase-dependent DNA fragmentation, but an infarct-size reducing effect was not observed with either of these inhibitors.

Amino Acid Chloromethyl Ketones↗
PubMed2001

Dentin matrix protein 1 is predominantly expressed in chicken and rat osteocytes but not in osteoblasts.

Although osteocytes are the most abundant cells in bone, little is known about their function, and no specific marker protein for osteocytes has been described. Dentin matrix protein 1 (DMP1) is an acidic phosphoprotein expressed in tooth organ and bone. Our previous work showed that in the chicken, which is not capable of forming tooth, DMPI messenger RNA (mRNA) is highly expressed in bone by Northern blot analysis. To clarify the significance of DMP1 expression in bone, the expression of DMP1 mRNA and its protein was examined in the chicken and rat. In the chicken, DMPI mRNA was detected only in bone tissues and was localized in osteocytes and preosteocytes but not in osteoblasts. Similarly, in the rat, DMPI mRNA was predominantly expressed in osteocytes and preosteocytes in bone matrix but not in osteoblasts located at the bone surface. Antiserum was raised against the peptide from rat DMP1, and the localization of DMP1 was examined by immunohistochemistry. In the development of bone, DMP1 was first detected in newly formed bone matrix after osteoblastic cells had been embedded within it. After the appearance of typical osteocytes, DMP1 was localized in the pericellular bone matrix of osteocytes, including their processes. These data show that DMP1 is a bone matrix protein specifically expressed in osteocytes and preosteocytes and suggest that DMP1 plays a role in bone homeostasis because of its high calcium ion-binding capacity.

Animals↗