Biomedical subjects

T Noumura

Publications and source records attributed to T Noumura.

At least 19 recordsLinked to original sources

PubMed1996

Impaired development of CD4+ CD8+ thymoyctes by csk-'knock-in' into fyn locus.

p59fyn is one of the Src-family kinases thought to play an important role in signaling through T cell receptor. However, Fyn deficiency has caused no overt defects in vivo on T cell development, nor has it caused any changes in the phosphorylation status of molecules such as ZAP-70 which have been proposed as p59fyn substrates. This could be explained as being due to compensation of Fyn deficiency by other Src-family kinases. Here, we have 'knocked-in' the csk gene, a negative regulator of Src-family kinases, into fyn locus to challenge the problem of redundant functions among Src-family kinases. The csk-'knock-in' mice displayed atrophy of the thymic cortex and impaired development of CD4+ CD8+ thymocytes. This was concomitant with decrease in tyrosine phosphorylation of ZAP-70 and p120cbl.

Animals↗

PubMed1996

p59fyn-p125FAK cooperation in development of CD4+CD8+ thymocytes.

p59fyn is an Src family nonreceptor tyrosine kinase that has been suggested to play an important role in T-cell development and function. p125FAK is a unique nonreceptor tyrosine kinase and has been known to respond to integrin-extracellular matrix interactions. To examine their roles in thymocytes, heterozygous fak mutation was introduced into homozygous Fyn deficiency. The double mutation, but neither Fyn deficiency nor FAK heterozygosity alone, displayed impaired development of CD4+CD8+ thymocytes with atrophy of the thymic cortex, suggesting a unique cooperation between p59fyn and p125FAK in CD4+CD8+ T-cell development.

Animals↗

PubMed1996

Effects of inhibin on rat gonadal differentiation and development in vitro.

Previously we examined that inhibin-alpha subunit, transforming growth factor-beta 1 (TGF-beta 1) and epidermal growth factor (EGF) were expressed in sex-, cell- and stage-specific manners in perinatal rat gonads. To clarify effects of these growth factors on the rat gonadal differentiation and development, indifferent gonadal primordia with mesonephric tubules on gestational day 13 were cultured in vitro for 4 days in serum-free CMRL-1066 medium with inhibin, TGF-beta 1, EGF, anti-sera against these growth factors, testosterone or estradiol-17 beta, and then morphologically examined with reference to seminiferous tubule formation, germ cell division, Wolffian and Müllerian duct development. In male gonads, anti-inhibin-alpha serum suppressed the seminiferous tubule formation but inhibin, TGF-beta 1, EGF or steroid hormones did not affect on the tubule formation, germ cell proliferation nor gonoduct development. Seminiferous tubules in male gonads cultured in the medium containing anti-inhibin-alpha serum were incomplete and irregular in shape. On the other hand, in female gonads, inhibin suppressed the germ cell division and anti-inhibin-alpha serum led to the necrosis of germ cells, but other factors affected to neither sex cord formation nor germ cell division. Testosterone and estradiol-17 beta stimulated female Wolffian and Müllerian duct development, respectively. These results indicate that inhibin induces the seminiferous tubule formation and suppresses the female germ cell division in developing rat gonads in vitro.

Animals↗

PubMed1995

Integrin stimulation decreases tyrosine phosphorylation and activity of focal adhesion kinase in thymocytes.

FAK, focal adhesion kinase, is expressed in a variety of cell types and has been suggested to transduce signals brought about by integrin-extracellular matrix (ECM) interactions. Integrin stimulation increases tyrosine phosphorylation and activity of FAK in all the cells examined to date. In contrast, in thymocytes stimulation of VLA-4 (alpha 4 beta 1) and LFA-1 (alpha L beta 2) resulted in a marked decrease in tyrosine phosphorylation and activity of FAK.

Animals↗

PubMed1995

Immunohistochemical detection of the expression of the alpha subunit of inhibin, TGF-beta, basic-FGF and IGF-II in fetal ovarian grafts grown with fetal testes beneath the kidney capsule of adult castrated male rats.

In order to characterize the participation of growth factors in gonadal differentiation and development, we examined patterns of expression of the alpha subunit of inhibin, transforming growth factor-beta (TGF-beta), basic fibroblast growth factor (basic FGF) and insulin-like growth factor-II (IGF-II) immunohistochemically in experimentally induced ovotestes. Ovotestes were derived from ovaries of fetal rats on gestational day (GD) 13 that had been co-crafted with fetal testes (GD 17) beneath the kidney capsule of adult castrated males and examined on the 7th, 14th and 21st days after transplantation (TD). Reactivity with antibodies against the alpha subunit of inhibin and basic FGF was observed in the Sertoli cells in both ovotestes and testes on TD 14 and on TD7, 14 and 21, respectively. Expression of IGF-II was also recognized in the Leydig/interstitial cells in both types of graft on TD 14 and 21. Therefore, the gonadal somatic cells in the testicular region of the ovotestes had immunohistochemical properties similar to those in the cografted testes. However, the somatic cells in the ovarian region of the ovotestes had immunohistochemical profiles different from those in solitary grafted ovaries. The germ cells in the ovotestes showed some differences in patterns of expression when compared with those in cografted testes and solitary grafted ovaries: expression of basic FGF was recognized in the germ cells in ovotestes on TD 21 but not in co-grafted testes; expression of IGF-II was recognized in the germ cells in ovotestes on TD 21 but not in solitary grafted ovaries. These results indicate that the immunohistochemical properties that reflect expression of growth factors in female gonadal somatic cells were changed to properties that resemble those of male gonads by the co-grafted fetal testes.

Animals↗

PubMed1995

Developmental pattern of androgen receptor immunoreactivity in the mouse submandibular gland.

We studied the immunohistochemical localization of androgen receptor in the mouse submandibular gland, and developmental profiles of its expression using polyclonal human androgen receptor antibody. In the submandibular glands of both sexes, specific immunoreactivity appeared only in cell nuclei of the acini, the intercalated ducts, the granular convoluted tubules (GCT) and the excretory striated ducts. The percentage of immunoreactive cells in each region gradually declined with age during the first 90 days of postnatal development studied. The sexual difference in the percentage of immunoreactive cells was observed in the acini on days 20 and 30 and in the GCT on day 30. Incidence of immunoreactive cells in the female was significantly smaller than that in the male. On day 60, the percentage of immunoreactive cells of these two regions turned to increase slightly in the female but continued to decline in the male, and then it became higher in the female than in the male. In addition, one-week castration did not cause any changes in the intracellular distribution of androgen receptor and the percentage of immunoreactive cells in each region of the adult gland. These results suggest that androgen receptor is localized primarily in cell nuclei in all four regions of the mouse submandibular gland in situ, and that its expression in acini and GCT is superior in the male around days 20 to 30, when sex difference of the gland becomes evident.

Animals↗

PubMed1995

Immunohistochemical localization of insulin-like growth factor-II in the perinatal rat gonad.

To clarify the participation of insulin-like growth factor type-II (IGF-II) in rat gonadal differentiation, immunohistochemical localization of IGF-II was chronologically studied in Sprague-Dawley rat gonads from gestational day (GD) 13 to postnatal day (PD) 21 by using avidin-biotin complex technique. In male gonads, most cells were negative to IGF-II immunostaining during the perinatal period. Only Leydig/interstitial cells expressed positive reactivity from GD 21 to PD 11: the intensity of staining and the number of positive cells were gradually increased until PD 11. In female gonads, almost all cells showed negative immunoreactivity. Mesonephric tubules in both sexes exhibited slight or moderate reactivity on GD 13. These results indicate that IGF-II is likely to participate in the regression of fetal-type Leydig cells and/or the proliferation of adult-type Leydig cells around birth, and in the development of mesonephric tubules in the initial stage of gonadal differentiation.

Aging↗

PubMed1994

Cell- and stage-specific expression of basic FGF in the developing rat gonads.

In order to clarify the participation of basic fibroblast growth factor (bFGF) in rat gonadal differentiation and development, immunohistochemical localizations of bFGF were chronologically studied in Sprague-Dawley rat gonads from gestational day (GD) 13 to postnatal day (PD) 21 by using avidin-biotin complex technique. Immunohistochemical reactivity to bFGF antibody was positive in the germ cells. Slight or moderate immunostaining was seen in male germ cells from GD 18 to PD 5, and in female germ cells from PD 5 to 21. Leydig/interstitial cells in male gonads were slightly or moderately stained from GD 16 to PD 21. On the other hand, other types of gonadal cells were not stained during the perinatal period. These results indicate that bFGF shows discrete cell- and stage-specific patterns of expression in gonads during the perinatal period and is likely to participate in control of gonadal development in rats.

Animals↗

PubMed1993

Type I collagen promotes modulation of cultured rabbit arterial smooth muscle cells from a contractile to a synthetic phenotype.

The phenotypic transition of smooth muscle cells (SMC) from a contractile to a synthetic state appears to be an early event in the pathogenesis of atherosclerosis. We examined the effects of extracellular matrix components on the phenotypic modulation of rabbit arterial SMC in primary culture by flow cytometry. The results demonstrate that freshly isolated SMC attached, spread, and started to proliferate on type I collagen as well as on fibronectin. Moreover, type I collagen was as efficient as fibronectin in promoting the transition of the cells into the synthetic phenotype without exogenous mitogens. However, unlike on fibronectin, the synthetic peptide GRGDSP (Gly-Arg-Gly-Asp-Ser-Pro) and the peptide KDGEA (Lys-Asp-Gly-Glu-Ala), which contains the recognition sequence for alpha 2 beta 1 integrin in type I collagen, interfered little with the attachment, spreading, and phenotypic modulation of the cells on type I collagen. On the other hand, the phenotypic modulation of the cells was counteracted by the anti-beta 1 integrin antibody. These findings indicate that type I collagen promotes the phenotypic transition of the rabbit arterial SMC by interacting with a cell surface receptor (beta 1 integrin family) for a cell-binding sequence without RGD and DGEA. In contrast, elastin, a major constituent of the media, suppressed the cell attachment and spreading and maintained the cells in the contractile phenotype as laminin. These results suggest diverse roles of type I collagen and elastin as well as of fibronectin and laminin in the control of the differentiated properties of arterial SMC.

Amino Acid Sequence↗

PubMed1993

Age-related changes in the mitogenic activity of heparin-binding growth factors in rat sera.

Sera from rats of either sex and different ages were examined for their ability to stimulate DNA synthesis in BALB/c 3T3 cells. The activity levels of sera from male and female rats were almost the same, with age-related changes in activity also being quite similar. Activity was considerably higher in infant rats (1-month-old), but then, at a young age (6-7 months), decreased drastically for male rats, but not significantly for female rats. It increased again in middle-aged rats (12-13 months old) and was maintained at the same level toward old age (24-26 months old) for both sexes. In order to determine what kinds of growth factors were responsible for these changes, we carried out heparin affinity chromatography on the sera of male rats. Four peaks were obtained for all sera, with individual peaks exhibiting specific age-related changes in activity. Among them a peak which was eluted at 1.1 M NaCl had very high activity. It showed a similar age-related change to that of the whole sera, except for a significant increase at old age, and the factor(s) included in the peak was found to be derived from platelets. These results suggested that the factor(s) in the peak was responsible for maintaining serum mitogenic activity at an old age. The experiments undertaken to characterize this factor suggested that it is a novel one.

Aging↗

PubMed1992

Effects of sex steroids on the development of sexual dimorphism in mouse innominate bone.

The sexual dimorphism of the innominate bone was examined in 14 strains of mice. In female mice of all strains, the pubis was significantly longer and thinner than that in the strain-matched males. In 13 of 14 strains, the ischium in the male was longer and thicker than in the female. In the testicular-feminized male (Tfm) mouse, the ischium was longer and thinner than that in the wild-type male, resembling that of the wild-type female. The pubis of the Tfm mouse was longer than in the wild-type males. The pubis width in the Tfm mouse was between those of the wild-type male and female. Gonadectomy at ages of 5, 10, 20, 30, and 60 days in both sexes showed that the ischium develops as the female type when sex hormones are absent. In contrast, postnatal testicular androgen induces the male-type ischium. Gonadectomy at 60 days had a slight effect on the pubis, indicating that sexual dimorphism of the pubis was determined before 60 days of age. Estrogen receptors (ER) were immunohistochemically demonstrated in bone cells of 0- to 60-day-old mice. ER was found exclusively in the periosteum of the pubis at the day of birth; however, it appeared in bone cells of all parts of pelvis at 10-60 days. These results indicate that sexual dimorphism of the pubis is consistent for the 14 mouse strains examined, and that the shape of the pubis is determined by sex steroids before 60 days of age. Since ER exist in the bone cells, morphogenesis of the pelvis may be regulated by these sex steroids.

Animals↗

PubMed1992

Identification of the phenotypic modulation of rabbit arterial smooth muscle cells in primary culture by flow cytometry.

In atherosclerotic lesions, smooth muscle cells (SMC) change from a contractile to a synthetic phenotype. The in vivo and in vitro phenotypic transformations of SMC have been confirmed by transmission electron microscopy (TEM), but the relationship between this change and the cell cycle is still unknown. We demonstrated the structural modulation of rabbit arterial SMC in primary culture by TEM and immunocytochemistry and simultaneously studied changes in two-dimensional histograms of the relative DNA and RNA contents by flow cytometry. During the first day of primary culture, the cells exhibited the contractile phenotype and were composed of a population in the G0 phase characterized by low contents of DNA and RNA. On the second day of culture, some of the cells (18.2%) had started but not completed the transition into the synthetic phenotype and a cell population in the G1A phase with an RNA content above the G0 level appeared in almost the same proportion. This cell population could be categorized as an "intermediate" type. Moreover, after 3 days when about three-quarters of the cells had undergone structural transition, the same proportion of cells had entered into the cycling phase, while some cells still remained in the G0 and G1A phases. Thus, cell cycle analysis by flow cytometry corresponded well with the observations obtained by TEM and immunocytochemistry. These results show that flow cytometry can rapidly and relatively conveniently monitor the process of phenotypic modulation in SMC and is a useful method for the analysis of such transitions.

Animals↗

PubMed1992

Disassembly of F-actin filaments in human endothelial cells cultured on type V collagen.

We examined the inhibitory activity of type V collagen on cell attachment and cell growth and the role of stress fibers and beta 1 integrin in cultured human endothelial cells. Human endothelial cells cultured on type V collagen attached temporarily to the substrate and formed stress fibers. However, the cells failed to proliferate and gradually detached from the substrate. After 24 h, the cells on type V collagen lacked discernible stress fibers (F-actin filaments) and exhibited dots in small aggregates of F-actin. In addition, the cells expressed little or no proteins as focal adhesions, including vinculin and beta 1 integrin. In contrast, the cells on fibronectin and type I collagen formed complete F-actin filaments, exhibited sufficient vinculin and beta 1 integrin, and grew logarithmically from 2 days. On the other hand, human smooth muscle cells formed complete F-actin filaments, revealed typical focal adhesions, and started to proliferate rapidly after 24 h on type V collagen as well as on fibronectin and type I collagen. Thus, the disassembly of F-actin filaments was observed as a specific phenomenon in human endothelial cells cultured on type V collagen. Moreover, the F-actin filaments disappeared from endothelial cells treated with cytochalasin D after 24 h and the cells detached from fibronectin and type I collagen with time, a result consistent with the observations on type V collagen. Accordingly, the disassembly of F-actin filaments in focal adhesions may result in the detachment of endothelial cells from type V collagen.

Actins↗

PubMed1992

Sexually dimorphic duct system of the submandibular gland in mouse with testicular feminization mutation (Tfm/Y).

The X-linked testicular feminization mutation (Tfm/Y) in the mouse is characterized by androgen insensitivity of the target cells. The aim of this study was to examine sexually dimorphic development of the submandibular gland of Tfm/Y mutant mice in comparison with those of wild-type male, wild-type female and heterozygous Tfm female mice. In either 30- or 90-day-old wild-type male mice, the granular convoluted tubules (GCT) of the glands were more developed, and the relative occupied areas (ROA) of GCT were superior to those of the age-matched wild-type and heterozygous Tfm females. In androgen-insensitive Tfm/Y mice, the glandular structures rather resembled the female glands, showing lower values of the ROA of the GCT. Sex differences in the mitotic rate were observed at 30 days of age, being significantly higher in the wild-type male GCT than in the female GCT. Thereafter, the mitotic rate of the wild-type male GCT declined to the female levels by 90 days of age. The mitotic rate of GCT in Tfm/Y mutants was as low as those of the females during observation periods. An other three regions, the acini, the intercalated ducts and the excretory striated ducts, were not significantly different in either the ROA or the mitotic rate among wild-type males and females, and Tfm/Y. On the other hand, either the ROA or the mitotic activity of GCT of the glands in Tfm/Y mutants was completely unaffected by 5 alpha-dihydrotestosterone (DHT).(ABSTRACT TRUNCATED AT 250 WORDS)

Androgen-Insensitivity Syndrome↗

PubMed1991

Growth hormone-releasing factor (GRF) suppresses the in vitro proliferation of mammotrophs from the adult rat.

In order to examine the hypothalamic control of acidophilic proliferation, anterior pituitary cells from adult female rats were cultured with or without rat growth hormone-releasing factor fragment 1-29 (GRF-29). Changes in the numbers of mammotrophs and somatotrophs during culture were measured by immunocytochemical staining. The addition of GRF suppressed the increase in the number of mammotrophs even at the very low concentration of 10(-12) M. The number of somatotrophs increased in the medium containing GRF. The increase in mammotroph number was blocked by cytosine arabinoside, a mitotic inhibitor. GRF had no effect on the in vitro proliferation of fibroblasts. These results indicate the important role of hypothalamic GRF in the differential growth and secretion of the acidophils in vivo.

Animals↗

PubMed1991

Effects of castration and sex steroids on sexually dimorphic development of the mouse submandibular gland.

The aims of this study were to characterize sexual dimorphism in the submandibular glands of young adult mice and to determine how sex differences arise during postnatal development. In the mouse submandibular glands, prominent sexual dimorphism was observed at 30 days of age, when the male gland was superior in both the relative occupied area (ROA) and the mitotic rate of the granular convoluted tubules (GCT) to those of the female. By neonatal castration, this sexual dimorphism was abolished, and the intraglandular structures of castrated males were similar to those of normal females. In castrated mice of both sexes, daily treatment with testosterone and 5 alpha-dihydrotestosterone for 10 days from 20 days induced only the ROA of the GCT to increase to the normal male levels but not those of the other three regions of the glands, the acini, intercalated ducts and excretory striated ducts. Testosterone responsiveness of the glands, considering both the glandular weight gain and the mitotic rate of the GCT, was significantly higher in castrated males than in castrated females. On the other hand, 17 beta-estradiol had no effect on the glands of castrated mice. Therefore, the present study suggests that the testicular hormones are responsible for the masculine development of GCT of the glands, but not the ovarian hormones, and that there is a sex difference in the responsiveness of the glands to testosterone, which is more effective in males than in females.

Animals↗

PubMed1987

Sexually dimorphic and laterally asymmetric development of the embryonic duck syrinx: effect of estrogen on in vitro cell proliferation and chondrogenesis.

The syrinx, the vocal organ in birds, shows sexual dimorphism in the duck, Anas platyrhynchos. At the cellular level, to examine the role of estrogen in sexually dimorphic and laterally asymmetric development of duck syrinx, cells dissociated from the right and left halves of sexually monomorphic and primitive masculine syrinxes from 10 2/3-day embryos of male and female ducks were cultured by the micromass culture method, with or without estrogen. In the absence of estrogen, primary cell cultures from either side of male syrinx revealed identical abilities in both cell proliferation and chondrogenesis. In the female cell cultures, the right- and left-side cells proliferated equally but the right-side cells accumulated a larger amount of sulfated proteoglycans than the left-side cells did. Both proliferation and chondrogenesis in the male cell cultures were more active than those in the female cell cultures. Estradiol inhibited significantly cell proliferation as well as chondrogenesis in cell cultures from either side of female syrinx. Cultures from right-side cells of male syrinx were less inhibited by estradiol in cell proliferation and especially in chondrogenesis than the other three cultures. Generally, in both sexes the left-side cells of syrinx were more responsive to estrogen than the right-side cells in diminishing proliferation and chondrogenesis. The present results suggest that estrogen inhibits both cell proliferation and chondrogenesis in the female syrinx and that this process may contribute to the development of sexual dimorphism in the duck syrinx.

Animals↗

PubMed1985

The heterogeneity of human fibroblasts as determined from the effects of hydrocortisone on cell growth and specific dexamethasone binding.

To elucidate the heterogeneity of human fibroblasts from lung and skin, the effects of hydrocortisone on cell proliferation and the specific dexamethasone binding to cells were studied. Hydrocortisone at physiological concentrations stimulated the proliferation in three strains of human fetal lung fibroblasts and inhibited it in two strains. There are two kinds of fibroblasts in the human fetal lung in addition to the human skin fibroblasts reported previously. Dexamethasone-binding experiments showed that human fibroblasts may be classified into two groups with respect to the dissociation constant (Kd) of the binding reaction. The heterogeneity of human fibroblasts shown by Kd could not be correlated to classification on the basis of the effects of hydrocortisone on cell proliferation. The differences in Kd for the binding reactions suggest differences in donor tissues from which human fibroblasts are derived.

Cell Division↗