Survey on the implementation status and reproductive outcomes of oocyte and ovarian tissue cryopreservation in Japan: Historical comparison with nationwide surveys

PURPOSE

To clarify the reproductive outcomes of fertility preservation (FP) treatment.

METHODS

We conducted a mailed-in questionnaire survey at institutions certified by the Japan Society of Obstetrics and Gynecology to investigate the number of oocyte cryopreservations (OC) and ovarian tissue cryopreservations (OTC) performed from December 2016 to the end of 2020. And, we conducted a detailed investigation of cases in which frozen specimens were used during the investigation period, and made historical comparisons with previous nationwide studies.

RESULTS

Responses were received from 114 out of 150 facilities (response rate: 76.0%) for OC and 43 out of 51 for OTC (response rate: 84.3%). Breast cancer was the most common disease among patients whose FP specimens were used. During the study period, 1237 OCs and 198 OTCs were performed. In addition, 57 cycles of embryo transfer (ET) using cryopreserved oocytes and 12 cases of ovarian tissue transplantation (OTT) were performed. The mean age of patients who underwent ET using cryopreserved oocytes was 34.8 (±5.8) years, with a median age of 36 years. The pregnancy rate per ET using cryopreserved oocytes was 26.3% and the live birth rate (LBR) was 17.5%. Further, the LBR per patient was 43.3%, and the pregnancy rate following OTTs was 33.3%. Also, controlled ovarian stimulation using the random start method or the combination of aromatase inhibitors had no effect on pregnancy outcome.

CONCLUSION

Implementation of both OCs and OTCs have markedly increased over time in Japan, with comparable reproductive outcomes as other reports.

The study of the efficiency of in vitro maturation of ovarian tissue oocytes in pediatric patients

PURPOSE

Although recent in vitro maturation (IVM) studies in pediatric patients have demonstrated successful retrieval and maturation of oocytes, the studies included only a small number of premenarchal patients. In the present study, we examined the potential use of oocyte retrieval and maturation for pediatric patients who undergo ovarian tissue cryopreservation (OTC).

METHODS

We retrospectively examined the clinical records of pediatric patients who underwent OTC at our institution between October 2015 and December 2022. Data on the age, primary disease, menstrual history, pre-procedure chemotherapy, anti-Müllerian hormone (AMH) level, number of oocytes collected ex vivo from ovarian tissue, and number of mature oocytes from IVM were examined.

RESULTS

Data of 60 pediatric patients (aged 1 to 17 years) were included for analysis. Oocytes were retrieved from 36 patients; the oocytes of 18 of these patients could be cryopreserved. The IVM rate was significantly lower in the premenarchal patients than in the postmenarchal patients. The number of mature oocytes retrieved from IVM was higher in the no-chemotherapy group than in the chemotherapy group. A significant positive correlation was observed between the AMH level and the IVM outcomes.

CONCLUSION

Oocyte retrieval and maturation in pediatric patients undergoing OTC is particularly useful in those not receiving chemotherapy. In patients receiving chemotherapy, the AMH level may be useful for predicting the IVM outcome. Activation of the oocyte maturation process in vivo in pediatric patients and better understanding of the major regulators of oocyte maturation are necessary to improve the utility of the IVM procedure.

Quantification of residual cryoprotectants and cytotoxicity in thawed bovine ovarian tissues after slow freezing or vitrification

STUDY QUESTION

How much residual cryoprotectant remains in thawed/warmed ovarian tissues after slow freezing or vitrification?

SUMMARY ANSWER

After thawing/warming, at least 60 min of diffusion washing in media was necessary to significantly reduce the residual cryoprotectants in ovarian tissues frozen by slow freezing or vitrification.

WHAT IS KNOWN ALREADY

Ovarian tissue cryopreservation (OTC) by slow freezing has been the conventional method; while the vitrification method has gained popularity for its practicality. The main concern about vitrification is how much potentially toxic residual cryoprotectant remains in the warmed tissues at the time of transplantation.

STUDY DESIGN, SIZE, DURATION

This was an animal study using the ovarian tissues from 20 bovine ovaries. The duration of this study was from 2018 to 2020.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Ovarian cortex tissues were prepared from 20 bovine ovaries and assigned randomly to groups of fresh (non-frozen) control, slow freezing with 1.5 M dimethyl sulfoxide (DMSO), 1.5 M 1,2-propanediol (PROH) and vitrification with 35% ethylene glycol (EG). The residual cryoprotectant concentrations in thawed/warmed tissues were measured by gas chromatography at the following time points: frozen (before thawing/warming), 0 min (immediately after thawing/warming), 30, 60 and 120 min after diffusion washing in media. Next, the ultrastructural changes of primordial follicles, granulosa cells, organelles and stromal cells in the ovarian tissues (1 mm × 1 mm × 1 mm) were examined in fresh (non-frozen) control, slow freezing with DMSO or PROH and vitrification with EG groups. Real-time quantitative PCR was carried out to examine the expressions of poly (ADP-ribose) polymerase-1 (PARP1), a DNA damage sensor and caspase-3 (CASP3), an apoptosis precursor, in thawed/warmed ovarian tissues that were washed for either 0 or 120 min and subsequently in tissues that were ex vivo cultured for 24 or 48 h. The same set of tissues were also used to analyze the protein expressions of gamma H2A histone family member X (γH2AX) for DNA double-strand breaks and activated caspase-3 (AC3) for apoptosis by immunohistochemistry.

MAIN RESULTS AND THE ROLE OF CHANCE

The residual cryoprotectant concentrations decreased with the extension of diffusion washing time. After 60 min washing, the differences of residual cryoprotectant between DMSO, PROH and EG were negligible (P > 0.05). This washing did not affect the tissue integrity or significantly elevate the percentage of AC3 and γH2AX positive cells, indicating that tissues are safe and of good quality for transplantation.

LARGE SCALE DATA

N/A.

LIMITATIONS, REASONS FOR CAUTION

Since the study was performed with ovarian tissues from bovines, generalizability to humans may be limited. Potential changes in ovarian tissue beyond 120 min were not investigated.

WIDER IMPLICATIONS OF THE FINDINGS

This study addresses concerns about the cytotoxicity of EG in warmed ovarian tissues and could provide insights when devising a standard vitrification protocol for OTC.

STUDY FUNDING/COMPETING INTEREST(S)

The study was funded by a Grant-in-Aid for Scientific Research (B) from the Japan Society for the Promotion of Science to N.S.

Radiofrequency identification tag system improves the efficiency of closed vitrification for cryopreservation and thawing of bovine ovarian tissues

PURPOSE

A radiofrequency identification (RFID) tag system was designed to streamline cryopreservation and thawing procedures. This study evaluated the usefulness of the RFID tag system for improving the efficiency of cryopreserving/thawing bovine ovarian tissue by the closed vitrification protocol.

METHODS

Six participants carried out closed vitrification and thawing of bovine ovarian tissues procedures using either the conventional or the new RFID tag method, and the time required to perform each step of the respective methods was measured. After normality of data was confirmed by the Shapiro-Wilk test, the significance of differences was assessed by the unpaired t test.

RESULTS

When closed vitrification was performed, the time required for each step showed a significant difference between the two methods (t(4) = 2.938, p = 0.042, d = 2.40), and the total cryopreservation time was 11 min shorter using the RFID tag system. When thawing was performed, the time required for each step also showed a significant difference between the two methods (t(4) = 2.797, p = 0.049, d = 2.28), and the total thawing time was 2 min shorter using the RFID tag system.

CONCLUSION

The RFID tag system tested in this study seems to be suitable for managing biological samples stored in liquid nitrogen. Adoption of an RFID tag system by fertility centers may not only improve the efficiency of cryopreserving/thawing reproductive tissues but could also reduce human error.

Involvement of Aquaporin-5 Water Channel in Osmoregulation in Parotid Secretory Granules

Aquaporins (AQPs) are a family of channel proteins that allow water or very small solutes to pass, functioning in tissues where the rapid and regulated transport of fluid is necessary, such as the kidney, lung, and salivary glands. Aquaporin-5 (AQP5) has been demonstrated to localize on the luminal surface of the acinar cells of the salivary glands. In this paper, we investigated the expression and function of AQP5 in the secretory granules of the rat parotid gland. AQP5 was detected in the secretory granule membranes by immunoblot analysis. The immunoelectron microscopy experiments confirmed that AQP5 was to be found in the secretory granule membrane. Anti-AQP5 antibody evoked lysis of the secretory granules but anti-aquaporin-1 antibody did not and AQP1 was not detected in the secretory granule membranes by immunoblot analysis. When chloride ions were removed from the solution prepared for suspending secretory granules, the granule lysis induced by anti-AQP5 antibody was inhibited. Furthermore, 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid, an anion channel blocker, blocked the anti-AQP5 antibody-induced secretory granule lysis. These results suggest that AQP5 is, expressed in the parotid gland secretory granule membrane and is involved in osmoregulation in the secretory granules.

Ca2+, calmodulin and phospholipids regulate nitricoxide synthase activity in the rabbit submandibular gland

Nitric oxide (NO) plays an important role as an intra- and intercellular signaling molecule in mammalian tissues. In the submandibular gland, NO has been suggested to be involved in the regulation of secretion and in blood flow. NO is produced by activation of NO synthase (NOS). Here, we have investigated the regulation of NOS activity in the rabbit submandibular gland. NOS activity was detected in both the cytosolic and membrane fractions. Characteristics of NOS in the cytosolic and partially purified membrane fractions, such as Km values for l-arginine and EC(50) values for calmodulin and Ca(2+), were similar. A protein band that cross-reacted with anti-nNOS antibody was detected in both the cytosolic and membrane fractions. The membrane-fraction NOS activity increased 1.82-fold with treatment of Triton X-100, but the cytosolic-fraction NOS activity did not. The NOS activity was inhibited by phosphatidic acid (PA) and phosphatidylinositol 4,5-bisphosphate (PIP(2)). The inhibitory effects of phospholipids on the NOS activity were relieved by an increase in Ca(2+) concentrations. These results suggest that the Ca(2+)- and calmodulin-regulating enzyme nNOS occurs in cytosolic and membrane fractions, and PA and PIP(2) regulate the NOS activity in the membrane site by regulating the effect of Ca(2+) in the rabbit submandibular gland.

Distribution and properties of arginase in the salivary glands of four species of laboratory mammals

Important progress in arginine metabolism includes the discovery of widespread expression of two isoforms of arginase, arginase I and II, not only in hepatic cells but also in non-hepatic cells, and the formation of nitric oxide, a widely distributed signal-transducing molecule, from arginine by nitric oxide synthase. Possible physiological roles of arginase may therefore include regulation of nitric oxide synthesis through arginine availability for nitric oxide synthase. In this paper, arginase was investigated in the submandibular, sublingual, and parotid glands of rat, mouse, guinea pig, and rabbit. From their arginase contents, the salivary glands of these species were divided into two groups. Variable levels of arginase activity were detected in the salivary glands of mouse and rat. However, salivary glands of rabbit and guinea pig had almost no arginase activity. The presence of nitric oxide synthase has been reported in all the salivary glands used in this study. Therefore, one of the important findings was the presence of species specificity in the co-localization of arginase and nitric oxide synthase in the salivary glands of the four species. The highest specific activity of arginase was found in mouse parotid gland. In rat, considerable arginase activity was detected in all three glands, at 3.6-7.3% of that in rat liver. In rat submandibular gland, arginase was detected in both cytosolic and particulate fractions. In addition, arginase was detected in isolated acinar cells, but not in duct cells. Experiments on the intracellular distribution and the effects of the arginase inhibitors ornithine and N(omega)-hydroxy-L-arginine (NOHA), suggested the presence of both arginase I and arginase II in rat submandibular gland.

Association of FcgammaRII with low-density detergent-resistant membranes is important for cross-linking-dependent initiation of the tyrosine phosphorylation pathway and superoxide generation

IgG immune complexes trigger humoral immune responses by cross-linking of FcRs for IgG (FcgammaRs). In the present study, we investigated role of lipid rafts, glycolipid- and cholesterol-rich membrane microdomains, in the FcgammaR-mediated responses. In retinoic acid-differentiated HL-60 cells, cross-linking of FcgammaRs resulted in a marked increase in the tyrosine phosphorylation of FcgammaRIIa, p58(lyn), and p120(c-cbl), which was inhibited by a specific inhibitor of Src family protein tyrosine kinases. After cross-linking, FcgammaRs and tyrosine-phosphorylated proteins including p120(c-cbl) were found in the low-density detergent-resistant membrane (DRM) fractions isolated by sucrose-density gradient ultracentrifugation. The association of FcgammaRs as well as p120(c-cbl) with DRMs did not depend on the tyrosine phosphorylation. When endogenous cholesterol was reduced with methyl-beta-cyclodextrin, the cross-linking did not induce the association of FcgammaRs as well as p120(c-cbl) with DRMs. In addition, although the physical association between FcgammaRIIa and p58(lyn) was not impaired, the cross-linking did not induce the tyrosine phosphorylation. In human neutrophils, superoxide generation induced by opsonized zymosan or chemoattractant fMLP was not affected or increased, respectively, after the methyl-beta-cyclodextrin treatment, but the superoxide generation induced by the insoluble immune complex via FcgammaRII was markedly reduced. Accordingly, we conclude that the cross-linking-dependent association of FcgammaRII to lipid rafts is important for the activation of FcgammaRII-associated Src family protein tyrosine kinases to initiate the tyrosine phosphorylation cascade leading to superoxide generation.

Ca(2+)-regulated nitric oxide generation in rabbit parotid acinar cells

In rabbit parotid acinar cells, the muscarinic cholinergic agonist methacholine induced an increase in the intracellular Ca(2+) concentration and provoked nitric oxide (NO) generation. Ca(2+)-mobilizing reagents such as thapsigargin and the Ca(2+) ionophore A23187 mimicked the effect of methacholine on NO generation. Methacholine-induced NO generation was inhibited by the removal of extracellular Ca(2+). Immunoblot analysis indicated that the antibody against the neuronal type of nitric oxide synthase (NOS) cross-reacted with NOS in the cytosol of rabbit parotid gland cells. Immunofluorescence testing showed that neuronal NOS is present in the cytosol of acinar cells but less in the ductal cells. NOS was purified approximately 8100-fold from the cytosolic fraction of rabbit parotid glands by chromatography on Sephacryl S-200, DEAE-Sephacel, and 29,59-ADP-Sepharose. The purified NOS was a NADPH- and tetrahydroxybiopterin-dependent enzyme and was activated by Ca(2+) within the physiological range in the presence of calmodulin. These results suggest that NO is generated by the activation of the neuronal type of NOS, which is regulated in rabbit parotid acinar cells by the increase in intracellular Ca(2+) levels induced by the activation of muscarinic receptors.

Bradykinin induces a rapid cyclooxygenase-2 mRNA expression via Ca2+mobilization in human gingival fibroblasts primed with interleukin-1 β

We have previously demonstrated that bradykinin potentiates prostaglandin E(2)release in human gingival fibroblasts pretreated with interleukin-1 beta (priming). In this study, we demonstrate a potentiating effect of bradykinin on cyclooxygenase-2 mRNA expression in the interleukin-1 beta-primed fibroblasts. Interleukin-1 beta (200 pg/ml) induced cyclooxygenase-2 mRNA expression, but not bradykinin (1 microM). However, bradykinin rapidly and markedly increased the cyclooxygenase-2 mRNA expression in the fibroblasts primed with interleukin-1 beta. In the primed fibroblasts, ionomycin and thapsigargin mimicked the potentiating effect of bradykinin on the cyclooxygenase-2 mRNA expression. Dexamethasone and actinomycin D completely suppressed not only the interleukin-1 beta-induced cyclooxygenase-2 mRNA expression, but also the bradykinin-induced cyclooxygenase-2 mRNA expression in the interleukin-1 beta-primed fibroblasts, although cycloheximide did not inhibit the effects of interleukin-1 beta and bradykinin. These results suggest that bradykinin-induced prostaglandin E2 synthesis is regulated at the level of the transcription of cyclooxygenase-2 mRNA via Ca2+ mobilization in the interleukin-1 beta-primed human gingival fibroblasts.

Identification of a novel response element in the rat bone sialoprotein (BSP) gene promoter that mediates constitutive and fibroblast growth factor 2-induced expression of BSP

Bone sialoprotein (BSP) is a sulfated and phosphorylated glycoprotein, found almost exclusively in mineralized connective tissues, that may function in the nucleation of hydroxyapatite crystals. We have found that expression of BSP in osteoblastic ROS 17/2.8 cells is stimulated by fibroblast growth factor 2 (FGF2), a potent mitogen for mesenchymal cells. Stimulation of BSP mRNA with 10 ng/ml FGF2 was first evident at 3 h ( approximately 2.6-fold) and reached maximal levels at 6 h ( approximately 4-fold). From transient transfection assays, a FGF response element (FRE) was identified (nucleotides -92 to -85, "GGTGAGAA") as a target of transcriptional activation by FGF2. Ligation of two copies of the FRE 5' to an SV40 promoter was sufficient to confer FGF-responsive transcription. A sequence-specific protein-DNA complex, formed with a double-stranded oligonucleotide encompassing the FRE and nuclear extracts from ROS 17/2.8 cells, but not from fibroblasts, was increased following FGF2 stimulation. Several point mutations within the critical FRE sequence abrogated the formation of this complex and suppressed both basal and FGF2-mediated promoter activity. These studies, therefore, have identified a novel FRE in the proximal promoter of the BSP gene that mediates both constitutive and FGF2-induced BSP transcription.

Complex gangliosides as cell surface inhibitors for the ecto-NAD+ glycohydrolase of CD38

Leukocyte cell surface antigen CD38 is a single-transmembrane protein whose extracellular domain has catalytic activity for NAD(+) glycohydrolase (NADase). We previously reported that b-series gangliosides inhibit the NADase activity of the extracellular domain of CD38 expressed as a fusion protein [Hara-Yokoyama, M., Kukimoto, I., Nishina, H., Kontani, K., Hirabayashi, Y., Irie, F., Sugiya, H., Furuyama, S., and Katada, T. (1996) J. Biol. Chem. 271, 12951-12955]. In the present study, we examined the effect of exogenous gangliosides on the NADase activity of CD38 on the surface of retinoic acid-treated human leukemic HL60 cells and CD38-transfected THP-1 cells. After incubation of the cells with G(T1b), inhibition of NADase activity was observed. The time course of inhibition was slower than that of the incorporation of G(T1b) into the cells, suggesting that incorporation into the cell membranes is a prerequisite for inhibition. Inhibition occurred efficiently when G(T1b) and CD38 were present on the same cells (cis interaction) rather than on different cells (trans interaction). Although gangliosides may affect localization of cell surface proteins, indirect immunofluorescence intensity due to CD38 was not affected after G(T1b) treatment. Comparison of the effect of G(T1b) and G(D1a) indicates that the tandem sialic acid residues linked to the internal galactose residue of the gangliotetraose core are crucial to the inhibition. These results suggest a novel role of complex gangliosides for the first time as cell surface inhibitors of CD38 through specific and cis interaction between the oligosaccharide moiety and the extracellular domain.

Parathyroid hormone regulation of bone sialoprotein (BSP) gene transcription is mediated through a pituitary-specific transcription factor-1 (Pit-1) motif in the rat BSP gene promoter

Bone sialoprotein (BSP) is a mineralized tissue-specific protein expressed by differentiated osteoblasts that appears to function in the initial mineralization of bone. Parathyroid hormone (PTH), which regulates serum calcium through its actions on bone cells, increases the expression of BSP in the rat osteosarcoma cell line (ROS 17/2.8). At 10(-8) M PTH (human 1-34 PTH), stimulation of BSP mRNA was first evident at 3 h ( approximately 3.8-fold), reached maximal levels at 6 h ( approximately 4.7-fold), and declined slowly thereafter. The effects of PTH, which were abrogated by cycloheximide (28 microg/ml), did not alter the stability of the BSP mRNA. The increased transcription was mimicked by both forskolin (10(-6) M) and isoproterenol (10(-7) M), and was also increased by 3-isobutyl-1-methylxanthine (IBMX; 10(-5) M), while the transcriptional activity induced by PTH was inhibited by the protein kinase A inhibitor, H89 (5x10(-6) M). From transient transfection assays using various BSP promoter-luciferase constructs, a pituitary-specific transcription factor-1 (Pit-1) regulatory element (nts -111 to -105) was identified as the target of transcriptional activation by PTH. Thus, transcriptional activity of constructs including the Pit-1 was enhanced approximately 4.7-fold by 10(-8) M PTH while 5'-ligation of the Pit-1 element conferred PTH regulation in an SV40 promoter construct. Binding of a nuclear protein, recognized by anti-Pit-1 antibodies, to a radiolabelled Pit-1-BSP probe was decreased in nuclear extracts prepared from PTH, forskolin and isoproterenol-stimulated ROS 17/2.8 cells. Moreover, co-transfection of ROS cells with a double-stranded Pit-1 oligonucleotide also increased luciferase activity. Collectively, these results indicate that PTH acts through a protein kinase A pathway involving cAMP to stimulate BSP transcription by blocking the action of a Pit-1-related nuclear protein that suppresses BSP transcription by binding a cognate element in the BSP promoter. Thus, we have identified a novel Pit-1 suppressor element in the rat BSP gene promoter that is the target of PTH-stimulated transcription of the BSP gene.

Characterization of nitric oxide synthase in the rat parotid gland

Nitric oxide (NO) acts as an inter- and intracellular signalling molecule of various cells such as vascular endothelium, macrophages, and neurones. NO is produced by nitric oxide synthase (NOS) from L-arginine. Here the characteristics of NOS in the rat parotid gland were investigated. Approximately 74% of total activity of NOS was present in the cytosolic fraction. For full activation of the NOS in the cytosolic fraction, tetrahydroxybiopterin, NADPH, Ca(2+) and calmodulin were needed as cofactors, because the activity was clearly reduced in the absence of tetrahydroxybiopterin, NADPH, or Ca(2+), or in the absence of calmodulin and presence of trifluoperazine, a calmodulin antagonist, in the reaction mixture. The partially purified NOS activity was completely abolished in the absence of calmodulin or Ca(2+), and activated by them in a dose-dependent manner; EC(50) for calmodulin and Ca(2+) were 10 and 340 nM, respectively. The K(m) for L-arginine was 1.57 microM. Immunoblot analysis revealed that a 165-kDa protein band in the rat parotid gland cytosolic fraction cross-reacted with a rabbit polyclonal antibody against human brain NOS. These results suggest that NOS of the rat parotid gland is a neuronal isoform and that its activity is regulated by physiological concentrations of calmodulin and Ca(2+).

Activation of NFkappaB is necessary for IL-1beta-induced cyclooxygenase-2 (COX-2) expression in human gingival fibroblasts

The immediate-early cyclooxygenase-2 (COX-2) gene encodes an inducible prostaglandin synthase enzyme which is implicated in inflammatory and proliferative diseases. COX-2 is highly induced during cell activation by various factors, including mitogens, hormones and cytokines. Since pro-inflammatory cytokine IL-1beta has been shown to induce prostaglandin E2 (PGE2) release in human gingival fibroblasts (HGF), here we analyzed the effect of IL-1beta on the expression of COX-2 and the activation of NFkappaB in HGF. Northern hybridization analysis revealed that IL-1beta (200 pg/ml) increased the expression of COX-2 mRNA in HGF. The effect of IL-1beta was abrogated by herbimycin A, a protein tyrosine kinase inhibitor, and enhanced by orthovanadate, a protein tyrosine phosphatase inhibitor. IL-1beta-induced PGE2 release was blocked by the tyrosine kinase inhibitor and increased by the tyrosine phosphatase inhibitor. The results of transient transfection assays using chimeric constructs of the human COX-2 promoter (nt -1432 approximately +59) ligated to a luciferase reporter gene indicated that IL-1beta stimulated the transcriptional activity approximately 1.5-fold. Gel mobility shift assays with a radiolabelled COX-2-NFkappaB oligonucleotide (nts-223 to-214) revealed an increase in the binding of nuclear proteins from IL-1beta-stimulated HGF. This increase of DNA-protein complex formation induced by IL-1beta was blocked by herbimycin A and another tyrosine kinase inhibitor, genistein. These results suggest that NFkappaB is an important transcription factor for IL-1beta-induced COX-2 gene expression, and is involved in inducing COX-2 gene transcription through tyrosine phosphorylation in HGF.

Bradykinin potentiates prostaglandin E(2) release in the human gingival fibroblasts pretreated with interleukin-1beta via Ca(2+) mobilization

Interleukin-1beta, a proinflammatory cytokine, causes a slow increase in prostaglandin E(2) release. On the other hand, bradykinin, a chemical mediator for inflammation, induces a rapid prostaglandin E(2) release. Simultaneous stimulation with interleukin-1beta (200 pg/ml) and bradykinin (1 microM) evoked a moderately synergistic increase in prostaglandin E(2) release in human gingival fibroblasts. However, in the human gingival fibroblasts pretreated with interleukin-1beta, bradykinin drastically enhanced prostaglandin E(2) release. NS-398, a specific inhibitor of cyclooxygenase-2, inhibited not only interleukin-1beta-induced prostaglandin E(2) release but also bradykinin-induced prostaglandin E(2) release in the human gingival fibroblasts pretreated with interleukin-1beta. Transcriptional and translational inhibitors such as actinomycin D, cycloheximide, and dexamethasone also suppressed the interleukin-1beta-induced prostaglandin E(2) release and the bradykinin-induced prostaglandin E(2) release in interleukin-1beta-pretreated human gingival fibroblasts. In the fibroblasts pretreated with interleukin-1beta, Ca(2+)-mobilizing reagents such as ionomycin and thapsigargin mimicked the potentiating effect of bradykinin on prostaglandin E(2) release. These results suggest that interleukin-1beta- and bradykinin-induced prostaglandin E(2) release is dependent on cyclooxygenase-2 and the potentiated effect of bradykinin in the human gingival fibroblasts primed with interleukin-1beta is caused by Ca(2+) mobilization.

Ribose 1,5-bisphosphate is a putative regulator of fructose 6-phosphate/fructose 1,6-bisphosphate cycle in liver

6-Phosphofructo-1-kinase and fructose-1,6-bisphosphatase are rate-limiting enzymes for glycolysis and gluconeogenesis respectively, in the fructose 6-phosphate/fructose 1,6-bisphosphate cycle in the liver. The effect of ribose 1,5-bisphosphate on the enzymes was investigated. Ribose 1,5-bisphosphate synergistically relieved the ATP inhibition and increased the affinity of liver 6-phosphofructo-1-kinase for fructose 6-phosphate in the presence of AMP. Ribose 1,5-bisphosphate synergistically inhibited fructose-1,6-bisphosphatase in the presence of AMP. The activating effect on 6-phosphofructo-1-kinase and the inhibitory effect on fructose-1,6-bisphosphatase suggest ribose 1,5-bisphosphate is a potent regulator of the fructose 6-phosphate/fructose 1,6-bisphosphate cycle in the liver.

Crystallization and preliminary X-ray diffraction analysis of the extracellular domain of the cell surface antigen CD38 complexed with ganglioside

The cell surface antigen CD38 is a multifunctional ectoenzyme that acts as an NAD(+) glycohydrolase, an ADP-ribosyl cyclase, and also a cyclic ADP-ribose hydrolase. The extracellular catalytic domain of CD38 was expressed as a fusion protein with maltose-binding protein, and was crystallized in the complex with a ganglioside, G(T1b), one of the possible physiological inhibitors of this ectoenzyme. Two different crystal forms were obtained using the hanging-drop vapor diffusion method with PEG 10,000 as the precipitant. One form diffracted up to 2.4 A resolution with synchrotron radiation at 100 K, but suffered serious X-ray damage. It belongs to the space group P2(1)2(1)2(1) with unit-cell parameters of a = 47.9, b = 94.9, c = 125.2 A. The other form is a thin plate, but the data sets were successfully collected up to 2.4 A resolution by use of synchrotron radiation at 100 K. The crystals belong to the space group P2(1) with unit-cell parameters of a = 57.4, b = 51.2, c = 101.1 A, and beta = 97.9 degrees, and contain one molecule per asymmetric unit with a VM value of 2.05 A(3)/Da.

Ribose 1,5-bisphosphate inhibits fructose-1,6-bisphosphatase in rat kidney cortex

Fructose-1,6-bisphosphatase is one of the regulatory enzymes of gluconeogenesis in kidney cortex. The effect of ribose 1,5-bisphosphate on fructose-1,6-bisphosphatase purified from rat kidney cortex was studied. Rat kidney cortex, fructose-1,6-bisphosphatase exhibited hyperbolic kinetics with regard to its substrate, but the activity was inhibited by ribose 1,5-bisphosphate at nanomolar concentrations. The inhibitory effect of ribose 1,5-bisphosphate on the fructose-1,6-bisphosphatase was enhanced in the presence of AMP, one of the inhibitors of fructose-1,6-bisphosphatase. Fructose-2,6-bisphosphate, which is an inhibitor of fructose-1,6-bisphosphatase, inhibited rat kidney cortex fructose-1,6-bisphosphatase activities at a low concentration of fructose-1,6-bisphosphate but a high concentration of fructose-1,6-bisphosphate relieved fructose-1,6-bisphosphatase from fructose-2,6-bisphosphate-dependent inhibition. On the contrary, fructose-1,6-bisphosphate was not effective for the recovery of fructose-1,6-bisphosphatase from ribose 1,5-bisphosphate-dependent inhibition. These results suggest that ribose 1,5-bisphosphate is a potent inhibitor and is involved in the regulation of fructose-1,6-bisphosphatase in rat kidney cortex.

Ribose 1,5-bisphosphate regulates rat kidney cortex phosphofructokinase

Phosphofructokinase (EC 2.7.1.11) is a major enzyme of the glycolytic pathway, catalyzing the conversion of fructose 6-phosphate to fructose 1,6-bisphosphate. In this study, we demonstrated the effect of ribose 1,5-bisphosphate on phosphofructokinase purified from rat kidney cortex. Ribose 1,5-bisphosphate relieved the phosphofructokinase from ATP inhibition and increased the affinity for fructose 6-phosphate at nanomolar concentrations. These activating effects of ribose 1,5-bisphosphate were enhanced in the presence of AMP. Ribose 1,5-bisphosphate reduced the inhibition of the phosphofructokinase induced by citrate. These results suggest that ribose 1,5-bisphosphate is an activator of rat kidney cortex phosphofructokinase and synergistically regulates the enzyme activity with AMP.

Presence of a complex containing vesicle-associated membrane protein 2 in rat parotid acinar cells and its disassembly upon activation of cAMP-dependent protein kinase

Amylase release from parotid acinar cells is mainly induced by the accumulation of intracellular cAMP, presumably through the phosphorylation of substrates by cAMP-dependent protein kinase (PKA). However, the molecular mechanisms of this process are not clear. In a previous study (Fujita-Yoshigaki, J., Dohke, Y., Hara-Yokoyama, M., Kamata, Y., Kozaki, S., Furuyama, S., and Sugiya, H. (1996) J. Biol. Chem. 271, 13130-13134), we reported that vesicle-associated membrane protein 2 (VAMP2) is localized at the secretory granule membrane and is involved in cAMP-induced amylase secretion. To study the formation of the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) complex containing VAMP2 in parotid acinar cells, we prepared rabbit polyclonal antibody against the peptide corresponding to Arg(47)-Asp(64) of VAMP2 (anti-SER4256). The recognition site of anti-SER4256 overlaps the domain involved in binding target membrane SNAREs (t-SNARES). Then we examined the condition of VAMP2 by immunoprecipitation with anti-SER4256. VAMP2 was not included in the immunoprecipitate from solubilized granule membrane fraction under the control conditions, but incubation with cytosolic fraction and cAMP caused immunoprecipitation of VAMP2. The effect of cytosolic fraction and cAMP was reduced by addition of PKA inhibitor H89. Addition of both the catalytic subunit of PKA and the cytosolic fraction allowed immunoprecipitation of VAMP2, whereas the PKA catalytic subunit alone did not. These results suggest that () the t-SNARE binding region of VAMP2 is masked by some protein X and activation of PKA caused the dissociation of X from VAMP2; and () the effect of PKA is not direct phosphorylation of X, but works through phosphorylation of some other cytosolic protein.

Propionic acid stimulates superoxide generation in human neutrophils

Short-chain carboxylic acids are the metabolic by-products of pathogenic anaerobic bacteria and are found at sites of infection in millimolar quantities. We previously reported that propionic acid, one of the short-chain carboxylic acids, induces an increase in intracellular Ca2+ ([Ca2+]i) in human neutrophils. Here we investigate the effect of propionic acid on superoxide generation in human neutrophils. Propionic acid (10 mm) induced inositol 1,4, 5-trisphosphate (IP3) formation and a rapidly transient increase in [Ca2+]i, but not superoxide generation, whereas 1 microm formylmethionyl-leucyl-phenylalanine (fMLP), a widely used neutrophil-stimulating bacterial peptide, stimulated not only IP3 formation and Ca2+ mobilization but also superoxide generation. The IP3 level induced by propionic acid was slightly lower than that induced by fMLP. The transient increase in [Ca2+]i induced by propionic acid immediately returned to the basal level, whereas a sustained increase in [Ca2+]i, which was higher than the basal level, following a transient increase in [Ca2+]i was induced by fMLP. The peak level induced by propionic acid was lower than that with fMLP. In the absence of extracellular Ca2+, thapsigargin, a potent inhibitor of endoplasmic reticulum Ca2+-ATPase, induced an increase in [Ca2+]i even after propionic acid stimulation, but not after fMLP. The Ca2+ ionophore A23187 and thapsigargin induced superoxide generation by themselves. Propionic acid enhanced the superoxide generating effect of A23187 and thapsigargin. These results suggest that Ca2+ mobilization induced by propionic acid is much weaker than that with fMLP, and propionic acid is able to generate superoxide in the presence of a Ca2+ ionophore and a Ca2+ influx activator.

Involvement of prostaglandins in histamine H1 receptor-operated Ca2+ entry in human gingival fibroblasts

In the absence of external Ca2+, 100 microM histamine evoked a transient increase in intracellular Ca2+ ([Ca2+]i), and subsequent addition of Ca2+ to the medium resulted in a sustained increase in [Ca2+]i in fura-2-loaded human gingival fibroblasts. These Ca2+ mobilizations are attributed to Ca2+ release from intracellular stores and Ca2+ entry, respectively. When the histamine H1 antagonist chlorpheniramine was added after the histamine-induced transient increase in [Ca2+]i, the Ca2+ entry induced by the addition of Ca2+ was inhibited. In the fibroblasts pretreated with cyclooxygenase inhibitors, indomethacin (1 microM) or aspirin (100 microM), histamine-induced Ca2+ entry was significantly inhibited, but not the transient [Ca2+]i increase. These results suggest that the histamine-induced Ca2+ entry requires the continuous binding of histamine to the H1 receptors and is regulated by prostaglandins, which are probably produced due to the H1 receptor activation.

Translocation of Arf1 to the secretory granules in rat parotid acinar cells

We investigated the interaction of ADP-ribosylation factor (Arf) with the secretory granules in rat parotid acinar cells. The 20. 5-kDa small-molecular-mass GTP-binding protein in the cytosolic fraction of rat parotid acinar cells was identified as ADP-ribosylation factor1 by using a pan-Arf monoclonal antibody and isotype-specific polyclonal antibodies for Arf proteins 1, 3, 5, and 6. Incubation of the cytosolic fraction with isolated secretory granule membranes in the presence of GTPgammaS resulted in the translocation of Arf1 from the cytosolic fraction to the secretory granule membranes. The translocation was not observed in the presence of GDPbetaS in place of GTPgammaS, indicating that the process is GTP-dependent. The immunoelectron microscopy experiment confirmed Arf1 is translocated to the secretory granules. A prior treatment of the granule membranes with trypsin inhibited the translocation of Arf1 at 2 mM Mg2+, but had no effect in the absence of Mg2+ (condition of spontaneous conversion of Arf-GDP to Arf-GTP). Thus, the trypsin-sensitive nucleotide exchange activity for Arf1 is probably associated with the secretory granule membranes. These results demonstrate Arf1 translocates to the secretory granules in rat parotid acinar cells.

ADP-ribosylation factors in rat parotid acinar cells

ADP-ribosylation factor (Arf) is a 20 kDa polypeptide that is a member of the Ras superfamily of small molecular mass GTP-binding proteins. In addition to an essential role of Arf1 in vesicle budding, recent observations suggest a role for Arf6 in calcium-dependent exocytosis in bovine adrenal chromaffin cells. In rat parotid acinar cells, exocytosis is cAMP-dependent and our findings suggest an interaction of Arf1 with the secretory granules. We describe here the structural and functional background to the Arf proteins focusing on their role in rat parotid acinar cells.

Snare proteins essential for cyclic AMP-regulated exocytosis in salivary glands

Rat parotid acinar cells secrete amylase through the stimulation of beta-adrenoceptors followed by accumulation of intracellular cAMP. However, it remains unclear at the molecular level how secretory granules fuse with the apical membranes. We have examined whether SNARE proteins are involved in exocytosis in the salivary glands, and have found that one of the SNARE proteins, VAMP-2, is localized at the secretory granule membrane of rat parotid acinar cells. Moreover, botulinum neurotoxin B, which has endoprotease activity that cleaves VAMP-2, inhibited cAMP-dependent amylase release but did not inhibit basal secretion in the absence of cAMP. These results suggest that VAMP-2 is essential for cAMP-regulated exocytosis in rat parotid acinar cells. In contrast, both neurotoxins A and C1 (endoproteases that cleave SNAP-25 and syntaxin 1 respectively) failed to inhibit cAMP-dependent amylase release. Therefore, neither SNAP-25 nor syntaxin 1 are involved in amylase secretion in the parotid glands. Clarification of the mechanism of secretion will require the identification of proteins that interact and function cooperatively with VAMP-2. This approach may also reveal details of the molecular mechanism by which the cAMP facilitates secretion in other systems, including neurotransmission.

Ca2+-nitric oxide-cGMP signaling in rabbit parotid acinar cells

Guanosine 3',5'-cyclic monophosphate (cGMP) is a second messenger generated in response to hormones or neurotransmitters in various tissues and cells. In parotid acinar cells, the activation of muscarinic cholinergic and beta-adrenergic receptors induces an increase in intracellular cGMP. However, the mechanism of cGMP production in parotid acinar cells has not been well elucidated. cGMP production is induced by the activation of guanylyl cyclases, which are directly activated by nitric oxide (NO). NO plays an important role as an inter- and intracellular signal molecule in various organs and cells. Biosynthesis of NO is catalyzed by NO synthase (NOS), and NO generation is controlled by the regulation of NOS activity, for example by Ca2+. We have studied the regulation of NOS activity, NO generation and cGMP production in rabbit parotid acinar cells, and have demonstrated a functional Ca2+-NO-cGMP signaling pathway.

cGMP production is coupled to Ca(2+)-dependent nitric oxide generation in rabbit parotid acinar cells

We investigated the mechanism of guanosine 3',5'-monophosphate (cGMP) production in rabbit parotid acinar cells. Methacholine, a muscarinic cholinergic agonist, stimulated cGMP production in a dose-dependent manner but not isoproterenol, a beta-adrenergic receptor stimulant. Methacholine-stimulated cGMP production has been suggested to be coupled to Ca2+ mobilization, because intracellular Ca2+ elevating reagents, such as thapsigargin and the Ca2+ ionophore A23187, mimicked the effect of methacholine. The cGMP production induced by Ca2+ mobilization has also been suggested to be coupled to nitric oxide (NO) generation because the effects of methacholine, thapsigargin and A23187 on cGMP production were blocked by NG-nitro-L-arginine methyl ester (L-NAME), a specific inhibitor of nitric oxide synthase (NOS), and hemoglobin, a scavenger of nitric oxide (NO). Sodium nitroprusside (SNP), a NO donor, stimulated cGMP production. Furthermore, methacholine stimulated NO generation, and NOS activity in the cytosolic fraction in rabbit parotid acinar cells was exclusively dependent on Ca2+. These findings suggest that cGMP production induced by the activation of muscarinic cholinergic receptors is coupled to NO generation via Ca2+ mobilization.

Nitric oxide synthase activities in mammalian parotid and submandibular salivary glands

Nitric oxide is important as a physiological messenger molecule in various organs and cells. It is synthesized from the amino acid L-arginine by nitric oxide synthase. Here, the specific activities of nitric oxide synthase in the cytosolic fractions of rabbit, bovine, mice, rat, and guinea-pig parotid and submandibular glands were compared. Marked specific activities were detected in the rabbit and bovine parotid and submandibular glands and in the parotid of mice. The activity in rabbit parotid was highest and was similar to that in rabbit brain. The significant activities in the salivary glands were completely blocked in the absence of Ca2+ or the presence of a calmodulin inhibitor. These findings suggest that the rabbit parotid glands are useful for studying the regulation of nitric oxide generation by Ca2+/calmodulin-dependent nitric oxide synthase in salivary glands.

Transforming growth factor-beta 1 regulation of bone sialoprotein gene transcription: identification of a TGF-beta activation element in the rat BSP gene promoter

Transforming growth factor-beta (TGF-beta) increases steady-state mRNA levels of several extracellular matrix proteins in mineralized connective tissues. Bone sialoprotein (BSP) is a major constituent of the bone matrix, thought to initiate and regulate the formation of mineral crystals. To determine the molecular pathways of TGF-beta 1 regulation of bone proteins, we have analyzed the effects of the TGF-beta 1 on the expression of the BSP in the rat osteosarcoma cell line (ROS 17/2.8). TGF-beta 1 at 1 ng/ml, increased BSP mRNA levels in ROS 17/2.8 cells approximately 8-fold: the stimulation was first evident at 3 hr, reached maximal levels at 12 hr and slowly declined thereafter. Since the stability of the BSP mRNA was not significantly affected by TGF-beta 1, and nuclear "run-on" transcription analyses revealed only a approximately 2-fold increase in the transcription of the BSP gene, most of the increase in BSP mRNA appeared to involve a nuclear post-transcriptional mechanism. Moreover, the effects of TGF-beta 1 were indirect, since the increase in BSP mRNA was abrogated by cycloheximide (28 micrograms/ml). To identify the site of transcriptional regulation by TGF-beta 1, transient transfection analyses were performed using BSP gene promoter constructs linked to a luciferase reporter gene. Constructs that included nt -801 to -426 of the promoter sequence were found to enhance transcriptional activity approximately 1.8-fold in cells treated with TGF-beta 1. Within this sequence, approximately 500 nt upstream of the transcription start site, a putative TGF-beta activation element (TAE) was identified that contained the 5'-portion of the nuclear factor-1 (NF-1) canonical sequence (TTGGC) overlapping a consensus sequence for activator protein-2 (AP-2). The functionality of the TAE was shown by an increased binding of a nuclear protein from TGF-beta 1 stimulated cells in gel mobility shift assays and from the attenuation of TGF-beta 1-induced luciferase activity when cells were co-transfected with a double-stranded TAE oligonucleotide. Competition gel mobility shift analyses revealed that the nuclear protein that binds to the TAE has similar properties to, but is distinct from, NF-1 nuclear protein. These studies have therefore identified a TGF-beta activation element (TAE) in the rat BSP gene promoter that mediates the stimulatory effects of TGF-beta 1 on BSP gene transcription.

Bradykinin regulates the histamine-induced Ca2+ mobilization via protein kinase C activation in human gingival fibroblasts

We previously demonstrated that histamine and bradykinin evoke an increase in intracellular Ca2+ ([Ca2+]i) in human gingival fibroblasts by using a fluorescent Ca2+ indicator Fura-2. In this paper, we further demonstrate the regulation of the histamine-induced Ca2+ mobilization by bradykinin. In fibroblasts stimulated with bradykinin (1 microM), subsequent stimulation with histamine (100 microM) failed to mobilize Ca2+, whereas bradykinin induced an increase in [Ca2+]i in the cells pre-stimulated with histamine. The attenuation of the histamine response was dependent on the concentration of bradykinin for the first stimulation. Histamine also failed to induce the formation of inositol 1,4,5-trisphosphate in fibroblasts pretreated with bradykinin. In fibroblasts pretreated with bradykinin (1 microM) for 3 min and then washed with fresh medium, the effect of histamine on [Ca2+]i quickly returned to the control level. The activation of protein kinase C by phorbol ester 12-O-tetradecanoyl-phorbol-13-acetate (PMA) elicited a marked decrease in histamine-induced Ca2+ mobilization. When the protein kinase C activity was inhibited with H7, a protein kinase C inhibitor, or was down-regulated by pretreatment with PMA for 20 h, the inhibitory effect of PMA on the histamine response was relieved. In the fibroblasts pretreated with H7 or PMA for 20 h, histamine evoked Ca2+ mobilization even after bradykinin stimulation. These results suggest that the histamine response is regulated by bradykinin receptor activation via the activation of protein kinase C in human gingival fibroblasts.

Cementum, root dentin and bone extracts stimulate chemotactic behavior in cells from periodontal tissue

In this paper, we used the extracts from cementum, bone, dentin and enamel, and compared the chemotactic behavior of human periodontal ligament (HPDL) cells, human gingival fibroblasts (HGF) and human alveolar bone (HAB) cells using modified Boyden chambers. The extracts, obtained using 4 M guanidine HCl ("G" extract), from cementum, root dentin, and bone had greater chemotactic effects than all the 4 M guanidine HCl/0.5 M EDTA extracts ("E" extract). HPDL cells and HGF exhibited higher chemotactic behavior than osteoblast-like HAB cells in response to cementum and root dentin "G" extracts. On the other hand, HAB cells showed the highest migratory activity in response to the bone "G" extract. The chemotactic activities of these extracts were reduced by heat- and trypsin-treatment. These results suggest that proteinaceous chemotactic factors exist in the cementum, root dentin and bone, and they appear to regulate the migration and orientation of HPDL cells, HGF and HAB cells during periodontal wound healing.

Histamine H1 receptor-induced Ca2+ mobilization and prostaglandin E2 release in human gingival fibroblasts. Possible role of receptor-operated Ca2+ influx

Stimulation of human gingival fibroblasts with histamine elicited an increase in the intracellular concentration of free calcium ([Ca2+]i) and the formation of inositol 1,4,5-trisphosphate (InsP3) in a concentration- and time-dependent manner. The histamine-induced increase in [Ca2+]i was attenuated completely by chlorpheniramine, an H1 antagonist, but not by cimetidine, an H2 antagonist. The histamine-induced Ca2+ response consisted of an initial transient peak response and a subsequent sustained increase. The transient phase can be largely attributed to Ca2+ release from intracellular InsP3-sensitive stores since the increased [Ca2+]i effect of histamine completely disappeared after depletion of intracellular Ca2+ stores with thapsigargin in the absence of extracellular Ca2+. The sustained phase was due to Ca2+ influx which was attenuated in the absence of extracellular Ca2+. The Ca2+ influx required the continuous binding of histamine to the receptor, since chlorpheniramine attenuated the increase in [Ca2+]i observed when extracellular Ca2+ was re-applied to the cells after stimulation with histamine in the absence of extracellular Ca2+. Pretreatment with the Ca2+ channel blocker SK&F96365 inhibited the Ca2+ influx component, suggesting that histamine stimulates Ca2+ influx through an H1 receptor-operated Ca2+ channel. Histamine also evoked a concentration- and time-dependent release of prostaglandin E2 (PGE2). The histamine-evoked PGE2 release was reduced markedly by exclusion of extracellular Ca2+ or pretreatment with SK&F96365 or an H1 antagonist. These results indicate that histamine stimulates both the intracellular Ca2+ release from InsP3-sensitive stores and the H1 receptor-operated Ca2+ influx from extracellular sites. The increased [Ca2+]i due to the Ca2+ influx causes PGE2 release in human gingival fibroblasts.

Vesicle-associated membrane protein 2 is essential for cAMP-regulated exocytosis in rat parotid acinar cells. The inhibition of cAMP-dependent amylase release by botulinum neurotoxin B

Amylase exocytosis of the parotid gland is mediated by intracellular cAMP. To investigate whether cAMP-dependent secretion has a mechanism similar to that of regulated neuroexocytosis, we examined the expression of synaptosome-associated proteins. In rat parotid acinar cells, we found 25 (p25) and 18 kDa (p18) proteins reacted with antibodies against Rab3A and vesicle-associated membrane protein 2 (VAMP-2), respectively. On the other hand, syntaxin 1 and SNAP-25, which interact with VAMP-2 at synapses, were undetectable. Rab3A-like p25 and VAMP-2-like p18 were also expressed in other exocrine acinar cells. The latter was localized at secretory granule membranes, and the former was detected in secretory granule and cytosolic fractions. The antibody against VAMP-2 used in this study did not react with cellubrevin, and p18 was cleaved with botulinum neurotoxin B. Thus, we identified p18 as VAMP-2. Botulinum neurotoxin B inhibited the cAMP-induced amylase release from streptolysin O-permeabilized acinar cells. Therefore, VAMP-2 is required for cAMP-regulated amylase release in rat parotid acinar cells. This is the first report that VAMP-2 is involved in regulated exocytosis that is independent of Ca2+.

Inhibition of NAD+ glycohydrolase and ADP-ribosyl cyclase activities of leukocyte cell surface antigen CD38 by gangliosides

We have recently reported that gangliosides act as inhibitors of ADP-ribosyltransferases and NAD+ glycohydrolases (NADase) of pertussis toxin and the C3 exoenzyme from Clostridium botulinum (Hara-Yokoyama, M., Hirabayashi, Y., Irie, F., Syuto, B., Moriishi, K., Sugiya, H., and Furuyama, S. (1995) J. Biol. Chem. 270, 8115-8121). Here, we investigated the effect of gangliosides on the enzymatic activity of leukocyte cell surface antigen CD38, which is identified as an ecto-NADase (Kontani, K., Nishina, H., Ohoka, Y., Takahashi, K., and Katada, T. (1993) J. Biol. Chem. 268, 16895-16898). Gangliosides GM1a and GQ1balpha inhibited the NADase activity in the immunoprecipitate of anti-CD38 antibody from the membrane extract of retinoic acid-treated human leukemic HL-60 cells. Gangliosides also inhibited the NADase activity of the extracellular domain of CD38 antigen that was deprived of the transmembrane domain and was expressed in Escherichia coli as a fusion protein with maltose-binding protein (MBP-CD38). The order of the inhibitory effect of purified ganglioside species on the NADase activity on MBP-CD38 was as follows: GQ1balpha > GT1b, GQ1b > GD1a, GD1b, GM1a, GM1b, GD3, GM3. GQ1balpha inhibited the NADase of MBP-CD38 in a noncompetitive manner versus NAD+ with a Ki value of about 0.3 microM. Neither ceramide nor the oligosaccharide moiety of GQ1balpha had an effect on the NADase activity. GQ1balpha, GT1b, and GQ1b also efficiently inhibited the ADP-ribosyl cyclase activity of MBP-CD38. At present, gangliosides are the only endogenous species that can block the enzymatic activity of CD38 antigen. The present results suggest a potential role of gangliosides as inhibitors of the ecto-NADases.

Histamine H1 receptor-stimulated Ca2+ signaling pathway in human periodontal ligament cells

We studied histamine-induced Ca2+ mobilization in human periodontal ligament (HPDL) cells. Histamine induced a transient rise in intracellular Ca2+ ([Ca2+]i) and maintained a sustained phase in the presence of extracellular Ca2+. In the absence of extracellular Ca2+, the transient peak was slightly reduced and the sustained phase was decreased to the basal level. The initial rise in [Ca2+]i was attributed to two components: intracellular Ca2+ release and Ca2+ influx, whereas the sustained phase was due to Ca2+ influx. After depletion of intracellular Ca2+ stores with thapsigargin, a known Ca(2+)-ATPase inhibitor, histamine-induced increase in [Ca2+]i was significantly reduced, suggesting histamine induces Ca2+ release from inositol 1,4,5-trisphosphate [Ins(1,4,5)P3]- and thapsigargin-sensitive Ca2+ stores. Histamine-induced peak in [Ca2+]i was increased dose-dependently in the presence and absence of extracellular Ca2+. The histamine-mediated response in [Ca2+]i was specifically attenuated by chlorpheniramine (H1 antagonist) but not by cimetidine (H2 antagonist), clearly indicating that activation of H1 receptor mediates histamine-induced Ca2+ mobilization. We next examined the effect of histamine on inositol phosphates formation. Histamine stimulated the formation of inositol phosphates which changed time-dependently. In particular, the formation of Ins(1,4,5)P3 was increased significantly for 10 s. The histamine-induced Ca2+ mobilization caused an increase of prostaglandin E2 (PGE2) release which was reduced in excluding extracellular Ca2+. These results indicate that activation of histamine H1 receptor induces the accumulation of Ins(1,4,5)P3 and the following transient increase in [Ca2+]i, and elicits the release of PGE2 which may be coupled with Ca2+ influx.

Comparison of the characteristics of human gingival fibroblasts and periodontal ligament cells

To elucidate the characteristics of human periodontal ligament cells, we compared these cells with gingival fibroblasts isolated from the periodontal tissues of female human subjects. Human periodontal ligament (HPDL) cells had a sharper spindle shape and exhibited a higher growth rate than human gingival fibroblasts (HGF). HPDL cells had a high level of alkaline phosphatase (ALPase) activity, whereas HGF had a low level of such activity. Northern blot analysis demonstrated that HPDL cells produced ALPase mRNA. Decorin and biglycan mRNA were detected in both HPDL cells and HGF, whereas osteocalcin and bone sialoprotein mRNA was not detected in either cells. Both HPDL cells and HGF responded to prostaglandin E2 (PGE2) and isoproterenol, and produced cyclic AMP (cAMP), but did not respond to human 1-34 parathyroid hormone (PTH). Intracellular Ca2+ ([Ca2+]i) was measured in HPDL cells and HGF, using Fura 2-AM. Bradykinin (BK) and histamine (HIS), which are major chemical mediators, caused a transient rise of [Ca2+]i in the presence of extracellular Ca2+. In HGF, but not HPDL cells, HIS induced a biphasic transient peak in [Ca2+]i. BK and HIS increased PGE2 release in both HPDL cells and HGF. However, HGF released a larger amount of PGE2 than HPDL cells. These results demonstrate that HPDL cells have quite different characteristics from HGF. HPDL cells proliferate at a higher rate than HGF, show higher levels of cAMP production and greater ALPase activity, and respond in a different fashion to chemical mediators (BK and HIS) compared with HGF.

Effects of bradykinin on Ca2+ mobilization and prostaglandin E2 release in human periodontal ligament cells

In fura-2-loaded human periodontal ligament (HPDL) cells, bradykinin induced a rapidly transient increase and subsequently sustained increase in cytosolic Ca2+ ([Ca2+]i). When external Ca2+ was chelated by EGTA, the transient peak of [Ca2+]i was reduced and the sustained level was abolished, implying the Ca2+ mobilization consists of intracellular Ca2+ release and Ca2+ influx. Thapsigargin, a specific Ca(2+)-ATPase inhibitor for inositol 1,4,5-trisphosphate (1,4,5-IP3)-sensitive Ca2+ pool, induced an increased in [Ca2+]i in the absence of external Ca2+. After depletion of the intracellular Ca2+ pool by thapsigargin, the increase in [Ca2+]i induced by bradykinin was obviously reduced. Bradykinin also stimulated formation of inositol polyphosphates including 1,4,5-IP3. These results suggest that bradykinin stimulates intracellular Ca2+ release from the 1,4,5-IP3-sensitive Ca2+ pool. Bradykinin stimulated prostaglandin E2 (PGE2) release in the presence of external Ca2+, but not in the absence of external Ca2+. Ca2+ ionophore A23187 and thapsigargin evoked the release of PGE2 in the presence of external Ca2+ despite no activation of bradykinin receptors. These results indicate that bradykinin induces Ca2+ mobilization via activation of phospholipase C and PGE2 release caused by the Ca2+ influx in HPDL cells.

The dephosphorylation of 22-kDa phosphoprotein by type 2B protein phosphatase in rat parotid acinar cells

In saponin-permeabilized rat parotid acinar cells, cyclic AMP and 3-isobutyl-1-methylxanthine stimulated the phosphorylation of three particulate proteins with molecular masses of 34, 26 and 22 kDa. The particulate fractions containing 22-kDa phosphoprotein were isolated from the cells labelled with [gamma-32P]ATP and used to study the dephosphorylation of the 22-kDa phosphoprotein. When the labelled fractions were incubated at 30 degrees C in the presence of 0.3 mM CaCl2 and 10 micrograms calmodulin, dephosphorylation of the 22-kDa phosphoprotein was evoked. Further addition of the type 2B phosphatase (Ca2+/calmodulin-stimulated protein phosphatase purified from bovine brain) resulted in a remarkable dephosphorylation of the 22-kDa phosphoprotein. Western immunoblotting showed that type 2B protein phosphatase exists in rat parotid acinar cells. These results suggest that type 2B protein phosphatase in those cells is involved in the dephosphorylation of the 22-kDa phosphoprotein.

Identification of gangliosides as inhibitors of ADP-ribosyltransferases of pertussis toxin and exoenzyme C3 from Clostridium botulinum

We have previously reported the presence of an endogenous inhibitory activity in bovine brain for the ADP-ribosylation of GTP-binding proteins catalyzed by pertussis toxin (PT) (Hara-Yokoyama, M., and Furuyama, S. (1989) Biochem. Biophys. Res. Commun. 160, 67-71). In the present study, we identified the inhibitor as a ganglioside. The screening of various gangliosides revealed that GQ1b alpha most effectively inhibited the ADP-ribosyltransferase activities of both the holoenzyme and the catalytic subunit of PT. GQ1b alpha is a ganglioside newly identified as one of the antigens recognized by the cholinergic neuron-specific antibody, anti-Chol-1 alpha (Hirabayashi, Y., Nakao, T., Irie, F., Whittaker, V.P., Kon, K., and Ando, S. (1992) J. Biol. Chem. 267, 12973-12978). GQ1b alpha also inhibited the PT-catalyzed NAD+ glycohydrolysis. Unlike PT activity, the ADP-ribosylation and the NAD+ glycohydrolysis catalyzed by the C3 exoenzyme from Clostridium botulinum type C were inhibited by GT1b and GQ1b. The ADP-ribosylation catalyzed by either PT or the C3 exoenzyme was not inhibited by ceramide, galactocerebroside, or sialic acid. In addition to the inhibitory action of gangliosides on ADP-ribosylation, the importance of gangliosides as regulators of NAD+ metabolism is discussed.

A constitutive effector region on the C-terminal side of switch I of the Ras protein

The "switch I" region (Asp30-Asp38) of the Ras protein takes remarkably different conformations between the GDP- and GTP-bound forms and coincides with the so-called "effector region." As for a region on the C-terminal side of switch I, the V45E and G48C mutants of Ras failed to promote neurite outgrowth of PC12 cells (Fujita-Yoshigaki, J., Shirouzu, M., Koide, H., Nishimura, S., and Yokoyama, S. (1991) FEBS Lett. 294, 187-190). In the present study, we performed alanine-scanning mutagenesis within the region Lys42-Ile55 of Ras and found that the K42A, I46A, G48A, E49A, and L53A mutations significantly reduced the neurite-inducing activity. This is an effector region by definition, but its conformation is known to be unaffected by GDP-->GTP exchange. So, this region is referred to as a "constitutive" effector (Ec) region, distinguished from switch I, a "switch" effector (Es) region. The Ec region mutants exhibiting no neurite-inducing activity were found to be correlatably unable to activate mitogen-activated protein (MAP) kinase in PC12 cells. Therefore, the Ec region is essential for the MAP kinase activation in PC12 cells, whereas mutations in this region only negligibly affect the binding of Ras to Raf-1 (Shirouzu, M., Koide, H., Fujita-Yoshigaki, J., Oshio, H., Toyama, Y., Yamasaki, K., Fuhrman, S. A., Villafranca, E., Kaziro, Y., and Yokoyama, S. (1994) Oncogene 9, 2153-2157).

Dephosphorylation of ribosomal protein S6 phosphorylated via the cAMP-mediated signaling pathway in rat parotid gland: effect of okadaic acid and Zn2+

The particulate proteins of 34, 26, and 22 kDa are phosphorylated on serine residues in the rat parotid gland by activation of the cAMP-mediated signaling system. The 34 kDa protein was identified as ribosomal protein S6 by immunoprecipitation with anti S6 peptide antibody. The dephosphorylation of S6 was observed by incubation of the particulate fraction of the saponin-permeabilized cells labeled with [gamma-32P]ATP in the presence of cAMP/3-isobutyl-1-methylxanthine. The dephosphorylation of S6 was inhibited by either okadaic acid, a potent inhibitor of protein phosphatase, or Zn2+, however, neither Ca2+ nor Mg2+ showed significant effect. S6 phosphatase activities detected by using the 32P-labeled S6 peptide as a substrate were inhibited by both okadaic acid and Zn2+. These results suggest that the dephosphorylation of S6 is mediated by the okadaic acid and Zn(2+)-sensitive phosphatases in the rat parotid gland.

Possible involvement of adenylylation in the modification of a 26 kDa protein in rat parotid acinar cells

1. Adenylylation, a posttranslational modification of proteins, was investigated in saponin-permeabilized acinar cells of the rat parotid gland. 2. When cells were incubated with [2,8-3H]ATP, several proteins, including a 26 kDa protein in the particulate fraction, were labeled. 3. Upon incubation of cells with [alpha-32P]ATP in the presence of cAMP and 3-isobutyl-1-methylxanthine, 32P-labeling of the 26 kDa protein was observed. 4. After treatment with snake venom phosphodiesterase, [32P]AMP was released from the 26 kDa protein. Such release was not observed when cells were labeled with [gamma-32P]ATP. 5. The 32P-labeling pattern of proteins with [alpha-32P]ATP was clearly different from that with [adenylate-32P]NAD+. 6. The results suggest that the 26 kDa protein is one of the adenylylation substrates in rat parotid acinar cells.

Presence of endogenous chemotactic factors for periodontal ligament cells in bovine cementum and bone

When bovine cementum and bone were subjected to sequential dissociative extraction first with 4 M guanidine HCl ('G' extract) and then with 4 M guanidine HCl/0.5 M EDTA ('E' extract), high chemotactic activities for periodontal ligament cells were detected in the 'G' extracts using modified Boyden chambers. The chemotactic activities in both tissue extracts were destroyed by trypsin and heat. However, the activities in bone extracts were more heat-stable than those in cementum. When both tissue extracts were separated into bound and unbound fractions by DEAE-Sephacel ion-exchange chromatography, the chemotactic activities in cementum were detected in the unbound fractions, and those in bone in the bound fractions, which were eluted by 1 M NaCl. These results suggest that cementum and bone contain different chemotactic protein factors for periodontal ligament cells.

Involvement of type 2C phosphatase in the dephosphorylation of 26 kDa phosphoprotein in rat parotid acinar cells

Phosphorylation of three particulate proteins with molecular masses of 34, 26, and 22 kDa was stimulated in the presence of cyclic AMP/3-isobutyl-1-methylxanthine in saponin-permeabilized rat parotid acinar cells. When the particulate fraction isolated from the cells labeled with [gamma-32p]ATP was incubated at 30 degrees C, dephosphorylation of the 26 kDa phosphoprotein occurred in the presence of Mg2+ or Mn2+. Okadaic acid had no effect on the Mg(2+)-dependent dephosphorylation of the 26 kDa phosphoprotein. Addition of the recombinant type 2C phosphatase, Mg(2+)-dependent and okadaic acid-insensitive phosphatase, caused a remarkable dephosphorylation of the 26 kDa phosphoprotein. These observations strongly suggest type 2C phosphatase is involved in the dephosphorylation of the 26 kDa phosphoprotein.

Immunological approach to identify calmodulin-stimulated phosphatase isozymes from bovine brain

Molecular cloning of human, mouse and rat brain CaM-stimulated phosphatase has suggested the existence of two genes for the alpha subunit of the enzymes. A alpha and A beta fragments of A alpha and A beta from rat brain library have been expressed in bacteria to produce specific anti-calcineurin A alpha and anti-calcineurin A beta antibodies (Kuno et al., J Neurochem 58: 1643-1651, 1992). Alternative mRNA splicing gives rise to additional calcineurin isozymes with some containing an insertion sequence of ATVEAIEADE. Antibody against synthetic peptide of this insertion sequence has been raised in this study. Three CaM-stimulated phosphatase isozymes previously purified from bovine brain (BPI, BPII, BPIII) (Yokoyama & Wang, J Biol Chem 266: 14822-14829, 1991), along with the bacterially expressed rat A alpha and A beta fragments, were analyzed by two calcineurin alpha subunit monoclonal antibodies VJ6 and VD3, the rat anti-calcineurin A alpha and anti-calcineurin A beta specific polyclonal antibodies, and the insertion peptide antibody. The bovine brain CaM-stimulated phosphatase isozymes BPI and BPIII reacted with both anti-calcineurin A alpha and anti-calcineurin A beta antibodies. While BPII reacted with anti-calcineurin A alpha but not anti-calcineurin A beta antibody, it differed from the expressed A alpha fragment in immunoreactivity towards the monoclonal antibodies. The results show that the bovine brain CaM-stimulated phosphatase isozymes cannot be simply categorized as derived from A alpha or A beta genes products.(ABSTRACT TRUNCATED AT 250 WORDS)