The expressions of claudin-1 and E-cadherin in junctional epithelium.

BACKGROUND AND OBJECTIVE: The epithelium provides an important barrier against microbial invasion. Tight junction structural proteins called claudins are known to contribute to the epithelial cell barrier. Junctional epithelium is located at a strategically important interface between gingival sulcus and is interconnected by desmosomes and gap junctions, but not by tight junctions. Although claudins are tight junction-associated proteins, they are also expressed in the epithelium despite its lack of tight junctions in invertebrates. Therefore, claudins may play an important role in junctional epithelium without tight junctions. E-cadherin is a key molecule in the formation of adherence junctions and desmosomes. In the present study, we aimed to investigate the expressions of claudin-1,claudin-3, claudin-7 and E-cadherin in the junctional epithelium of Fischer 344 rats. MATERIAL AND METHODS: Gingival tissues from Fischer 344 rats were analyzed by immunohistochemical staining for claudin-1, claudin-3, claudin-7, and E-cadherin. RESULTS: Intense staining for claudin-1 and E-cadherin were observed in the junctional epithelium. In contrast to claudin-1, claudin-3 was mainly expressed in oral gingival epithelium and claudin-7 could not be detected on immunohistochemical analysis of the rat gingiva. CONCLUSION: These data suggest that claudin-1 and E-cadherin exist in the junctional epithelium and may play an important role in epithelial barrier function.

Irsogladine maleate abolishes the increase in interleukin-8 levels caused by outer membrane protein 29 from Aggregatibacter (Actinobacillus) actinomycetemcomitans through the ERK pathway in human gingival epithelial cells.

BACKGROUND AND OBJECTIVE: Irsogladine maleate (IM) suppresses the increase in interleukin (IL)-8 production induced by outer membrane protein (OMP) 29 from Aggregatibacter (Actinobacillus) actinomycetemcomitans in cultures of human gingival epithelial cells (HGEC). However, how IM suppresses the OMP29-induced increase in IL-8 expression remains unknown. In this study, we focused on intracellular signaling pathways to elucidate the mechanism behind the suppression. MATERIAL AND METHODS: HGEC, which had been pretreated with inhibitors of intracellular signaling molecules, were exposed to OMP29 (1 microg/mL) with or without IM (1 microM). IL-8 expression at the mRNA and protein levels was examined by real-time polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. Extracellular signal-regulated kinase (ERK) activity was measured with a p44/42 mitogen-activated protein kinase assay kit. RESULTS: An ERK inhibitor, PD98059, as well as IM, obviated the OMP29-induced increase in IL-8 levels in HGEC. A Jun kinase inhibitor, SP600125, and a nuclear factor kappaB inhibitor, PDTC, did not influence the OMP29-induced increase in IL-8 mRNA expression. The OMP29 stimulated phosphorylation of ERK in HGEC. Irsogladine maleate inhibited the phosphorylation. CONCLUSION: The suppression of the phosphorylation of ERK by IM in HGEC culminates in inhibition of the OMP29-induced increase in IL-8.

Irsogladine maleate counters the interleukin-1 beta-induced suppression in gap-junctional intercellular communication but does not affect the interleukin-1 beta-induced zonula occludens protein-1 levels in human gingival epithelial cells.

BACKGROUND AND OBJECTIVE: Irsogladine maleate counters gap junctional intercellular communication reduction induced by interleukin-8 or Actinobacillus actinomycetemcomitans in cultured human gingival epithelial cells. Interleukin-1 beta is involved in periodontal disease. Little is known, however, about the effect of interleukin-1 beta on intercellular junctional complexes in human gingival epithelial cells. Furthermore, irsogladine maleate may affect the actions of interleukin-1 beta. In this study, we examined how interleukin-1 beta affected gap junctional intercellular communication, connexin 43 and zonula occludens protein-1, and how irsogladine maleate modulated the interleukin-1 beta-induced changes in the intercellular junctional complexes in human gingival epithelial cells. MATERIAL AND METHODS: Human gingival epithelial cells were exposed to interleukin-1 beta, with or without irsogladine maleate. Connexin 43 and zonula occludens protein-1 were examined at mRNA and protein levels by real-time polymerase chain reaction and western blotting, respectively. Gap junctional intercellular communication was determined using the dye transfer method. The expression of zonula occludens protein-1 was also confirmed by immunofluorescence. RESULTS: Interleukin-1 beta decreased connexin 43 mRNA levels, but increased zonula occludens protein-1 mRNA levels. Irsogladine maleate countered the interleukin-1 beta-induced reduction in gap junctional intercellular communication and connexin 43 levels. However, irsogladine maleate did not influence the increased zonula occludens protein-1 levels. CONCLUSION: The effect of interleukin-1 beta on gap junctional intercellular communication and tight junctions of human gingival epithelial cells is different. The recovery of gap junctional intercellular communication by irsogladine maleate in the gingival epithelium may be a normal process in gingival epithelial homeostasis.

Calcium-independent activation of hypothalamic type I protein kinase C by unsaturated fatty acids.

Among multiple subspecies of the protein kinase C (PKC) family, type I PKC from the hypothalamus, having the structure related to the gamma-sequence, responds to low concentrations of arachidonic acid to exhibit marked enzymatic activity. This mode of activation does not require elevated Ca2+ levels, nor does it depend on diacylglycerol and phospholipid. Type I PKC is expressed only in limited regions of central nervous tissues, such as the hypothalamus. This PKC subspecies is not detected in the pituitary gland. The results suggest that the activation of type I PKC may not always be directly associated with inositol phospholipid hydrolysis, and that this subspecies may play a role in the modulation of specialized functions of the hypothalamus.

Abrogation of protein phosphatase 6 promotes skin carcinogenesis induced by DMBA.

Somatic mutations in the gene encoding the catalytic subunit of protein phosphatase 6 (Ppp6c) have been identified in malignant melanoma and are thought to function as a driver in B-raf- or N-ras-driven tumorigenesis. To assess the role of Ppp6c in carcinogenesis, we generated skin keratinocyte-specific Ppp6c conditional knockout mice and performed two-stage skin carcinogenesis analysis. Ppp6c deficiency induced papilloma formation with 7,12-dimethylbenz (a) anthracene (DMBA) only, and development of those papillomas was significantly accelerated compared with that seen following DMBA/TPA (12-O-tetradecanoylphorbol 13-acetate) treatment of wild-type mice. NF-κB activation either by tumor necrosis factor (TNF)-α or interleukin (IL)-1ß was enhanced in Ppp6c-deficient keratinocytes. Overall, we conclude that Ppp6c deficiency predisposes mice to skin carcinogenesis initiated by DMBA. This is the first report showing that such deficiency promotes tumor formation in mice.

N200 component of event-related potentials in depression.

Event-related potentials (ERPs) recorded during a two-tone discrimination (oddball) task were examined in 36 drug-free depressed patients and 36 control subjects. At remission, the ERPs of 12 of the depressed patients were reexamined. In the depressed patients, although a group difference was not detected in the peak latency and amplitude of N200 to rare stimuli, the mean amplitude for the N200 latency range in the difference waves was smaller than in the control subjects. Mismatch negativity (N2a), which was elicited by rare stimuli, was reduced in amplitude; but N2b may have been evoked to frequent stimuli more in the patients than in the control subjects. Depressed subjects may have a deviance in the fully automatic cerebral mismatch process that is assumed to be related to mismatch negativity and provoke the controlled mismatch detection process (presumed to be associated with N2b) even to nontarget frequent stimuli. These findings were observed during remission; however, there was a tendency for the N2b amplitude to decrease and recover toward the level of the control subjects.

Kinetics of a naltrexone sustained-release preparation.

A biodegradable sustained-release naltrexone bead preparation containing 70% naltrexone in a physical mixture with a copolymer of 90% lactic acid and 10% glycolic acid was evaluated in three male subjects. Each subject received a 10-mg iv dose of naltrexone HCl and a 63-mg dose by subcutaneous implantation of naltrexone beads. Kinetics of naltrexone estimated from the intravenous dose indicated a plasma clearance range of 3.1 to 3.4 l/min and a t 1/2 range of 1.7 to 3.7 hr. After bead implantation, average plasma naltrexone levels were maintained at 0.3 to 0.4 ng/ml and naltrexol levels were at 0.4 to 1.0 ng/ml for a period of approximately 1 mo, during which urine naltrexone and naltrexol levels were about 20 to 30 and 70 to 200 ng/ml. It was estimated that approximately 70% to 77% of the dose was absorbed after bead implantation. There were no serious adverse effects other than tissue irritation in two of the three subjects.

Differential down-regulation of protein kinase C subspecies in KM3 cells.

The down-regulation of protein kinase C (PKC) subspecies in KM3 cells (a pre-B, pre-T cell line) has been examined. The PKC from KM3 cells was resolved into two subspecies, type II (mainly beta II) and type III (alpha), upon hydroxyapatite column chromatography. Biochemical and immunocytochemical analysis revealed that, when these cells were treated with 12-O-tetradecanoylphorbol 13-acetate (TPA), the time course of down-regulation of the PKC subspecies was different; type II PKC was translocated and depleted from the cell more quickly than type III enzyme. The results suggest that each PKC subspecies plays a different role in the cellular response to TPA and probably to other external stimuli.

A calcium-protease activator associated with brain microsomal-insoluble elements.

A factor which markedly activates Ca2+-dependent thiol protease (calpain) is associated with Triton X-100-insoluble materials, presumably structural elements such as cytoskeletons, of bovine brain microsomal fraction. This factor is extracted with 0.6 M KC1, and purified partially by sucrose density gradient centrifugation and hydroxyapatite column chromatography. The factor appears to be a heat-stable protein with an approximate Mr of 15 000. With casein as substrate this factor activates both calpain I and calpain II several-fold up to more than 10- fold without alteration of their affinity to Ca2+. Calmodulin is unable to substitute for this factor. A similar factor is associated with human platelet insoluble materials.

Selective activation of the gamma-subspecies of protein kinase C from bovine cerebellum by arachidonic acid and its lipoxygenase metabolites.

The gamma-subspecies of protein kinase C (PKC) apparently is expressed only in central nervous tissues, and at a high level in the cerebellum and hippocampus. gamma-PKC from bovine cerebellum, but not the alpha- or beta I/beta II-subspecies, is activated by micromolar concentrations of arachidonic acid (AA), in the absence of both phospholipid and diacylglycerol. A significant component of this activation is also calcium independent. Other unsaturated fatty acids are much less active in this respect. Among the AA metabolites tested, lipoxin A (5(S),6(R),15(S)-11-cis-isomer) was a potent, selective activator of the gamma-subspecies, and also, to a lesser extent, 12(S)-hydroxy-5,8,10,14-eicosatetraenoic acid could support activation. These results raise the possibility that AA and some of its lipoxygenase metabolites may function as messenger molecules in neurones to activate the gamma-subspecies of PKC.

Protein kinase C in rat brain synaptosomes. Beta II-subspecies as a major isoform associated with membrane-skeleton elements.

A small fraction (approximately 5%) of protein kinase C (PKC) in the adult rat brain synaptosomes is tightly associated with Triton X-100-insoluble components (most likely membrane-skeleton elements), and is solubilized only after denaturation with sodium dodecyl sulfate. The kinase domain of this PKC can be released as a soluble form after limited proteolysis with calpain, whereas the regulatory domain which binds phorbol ester remains insoluble. The PKC in this fraction was identified as the beta II-subspecies or its related molecule. Presumably, this enzyme subspecies is responsible for the phosphorylation of a major PKC substrate protein, growth-associated protein-43, which is located in nerve endings as well as in growth cones in association with the membrane-skeleton elements.

Protein kinase C during differentiation of human promyelocytic leukemia cell line, HL-60.

Protein kinase C (PKC) from human promyelocytic leukemia HL-60 cells can be resolved into three fractions (peak, a, b and c) by hydroxyapatite column chromatography. Peak a and c enzymes are indistinguishable from the brain type II PKC having beta (beta I and beta II)-sequence and type III having alpha-sequence, respectively. Peak b enzyme is a previously unidentified PKC subspecies that has enzymological properties subtly different from type I (having gamma-sequence), type II and type III PKC. Upon treatment of HL-60 cells with 1 microM retinoic acid, this peak b enzyme is decreased dramatically within 24 h, whilst peak a enzyme (beta-PKC) is increased, and peak c (alpha-PKC) enzyme is slightly decreased within 48 h. The result implies that the PKC subspecies in HL-60 cells have distinct functions during cell differentiation.

H1 histone stimulates limited proteolysis of protein kinase C subspecies by calpain II.

Limited proteolysis of protein kinase C (PKC) subspecies with Ca2(+)-dependent neutral protease II (calpain II) was remarkably stimulated by basic polypeptides, such as H1 histone and poly-L-lysine. This stimulatory effect was observed for proteolysis of the active form of PKC, which was associated with phospholipid and diacylglycerol. The inactive form of PKC was far less susceptible to proteolysis, both in the presence and absence of the basic polypeptides. The basic polypeptides did not appear to interact with calpain II, but made the PKC molecule more susceptible to proteolysis. The relative rates of cleavage of type I (gamma), II (beta), and III (alpha) PKC were 2:2:1. The available evidence suggests that, like calpain I, calpain II may also contribute to the down-regulation or depletion of PKC.

Phosphorylation of type II (beta) protein kinase C by casein kinase II.

Rat brain type II (beta) protein kinase C (PKC) was phosphorylated by rat lung casein kinase II (CK-II). Neither type I (gamma) nor type III (alpha) PKC was significantly phosphorylated by CK-II. CK-II incorporated 0.2-0.3 mol of phosphate into 1 mol of type II PKC. This phosphate was located at the single seryl residue (Ser-11) in the V1-variable region of the regulatory domain of the PKC molecule. A glutamic acid cluster was located at the carboxyl-terminal side of Ser-11, showing the consensus sequence for phosphorylation by CK-II. The velocity of this phosphorylation was enhanced by the addition of Ca2+, diolein, and phosphatidylserine, which are all required for the activation of PKC. Phosphorylation of casein or synthetic oligopeptides by CK-II was not affected by Ca2+, diolein, or phosphatidylserine. Available evidence suggests that CK-II phosphorylates preferentially the activated form of type II PKC. It remains unknown, however, whether this reaction has a physiological significance.

Comparison of calcium-activated, cyclic nucleotide-independent protein kinase and adenosine 3':5'-monophosphate-dependent protein kinase as regards the ability to stimulate glycogen breakdown in vitro.

A cyclic nucleotide-independent protein kinase, which was produced from its proenzyme upon limited proteolysis by a Ca2+-dependent protease (Takai, Y., Yamamoto, M., Inoue, M., Kishimoto, A., & Nishizuka , Y. (1977) Biochem. Biophys. Res. Commun. 77, 542-550), showed an ability to phosphorylate not only muscle glycogen phosphorylase kinase but also glycogen synthase, resulting in activation and inactivation of the respective enzymes, although the protein kinase was less active than adenosine 3':5'-monophosphate (cyclic AMP)-dependent protein kinase toward glycogen synthase. Available evidence indicates that this new protein kinase shows pleiotropic functions apparently similar to those described for cyclic AMP-dependent protein kinase. Nevertheless, these protein kinases were clearly distinguishable from each other in their response to cyclic nucleotides and susceptibility to protein inhibitor.

Calcium-dependent neural proteases, widespread occurrence of a species of protease active at lower concentrations of calcium.

A species of neutral protease having high affinity for Ca2+ in the 10(-5) M range, originally found in canine cardiac muscle (Mellgren, R.L. (1980) FEBS Lett. 109, 129-133), is detected in a wide variety of rat tissues when a sensitive assay with 125I-iodinated casein as substrate is employed. This species of protease absolutely requires Ca2+, and other divalent cations are practically inactive. Although the activity of this enzyme apparently shows striking diversity among tissues tested, the enzymes obtained from various sources reveal similar physical and kinetic properties, and are capable of activating as Ca2+-activated, phospholipid-dependent protein kinase by limited proteolysis. The enzyme has a pH optimum at 7.5 to 8.0 and a molecular weight of about 8.8 X 10(4). The enzyme in its purified form is very sensitive to leupeptin and other thiol-protease inhibitors, but that in crude preparations is far less susceptible to the same inhibitors.

A role of membranes in the activation of a new multifunctional protein kinase system.

A new multifunctional protein kinase, which normally exists as an inactive form in the soluble fraction in mammalian tissues, attaches to membranes to exhibit full enzymatic activity. A low concentration of Ca2+ is absolutely necessary for this activation. This process is reversible. cAMP shows no effect. The active factors in membranes are phosphatidylinositol, phosphatidylserine, phosphatidic acid, diphosphatidylglycerol, and phosphatidylethanolamine in that order. Phosphatidylcholine and sphingomyelin are far less effective. Cytoplasmic as well as other membrane fractions from various tissues are active in supporting the enzymatic activity. A possible role of this Ca2+ and phospholipid-activated protein kinase system in transmembrane control is proposed.

Primary lymphoma of spermatic cord.

Primary lymphomas of spermatic cord are extremely rare. In a review of the world medical literature, until now, only fourteen cases of spermatic cord lymphoma have been reported, and, furthermore, they have a poor prognosis even in patients with stage I disease. Herein, we report a new case of primary non-Hodgkin's lymphoma of the spermatic cord. In August, 1993, 76-year-old man visited an urological hospital with a compaint of a right intrascoral mass, and underwent orchiectomy. Macroscopically no invasive lesion in the testis was observed, and the tumorous lesion was restricted to the epididymis. The histopathological study indicated that he suffered from primary malignant lymphoma of the spermatic cord (B-cell, diffuse medium-sized cell type). As radiographic investigations showed no other invasive lesion, the patient was diagnosed to be in stage IE. He was followed only with clinical observation, and, in August, 1996, relapsed with extensive disease in the abdoninal cavity, and was transferred to our hospital. Fourty months after the orchiectomy, he died of progression of disease irrespective of the salvage radio-chemotherapies given to him.

The treatment of affective disorder with carbamazepine: prophylactic synergism of lithium and carbamazepine combination.

1. In order to examine the prophylactic interaction between lithium and carbamazepine (CBZ), 18 patients who had been treated prophylactically with a combination of lithium and CBZ (combination therapy), lithium alone (Li-therapy), or CBZ alone (CBZ-therapy) were investigated in terms of episode occurrence. 2. The results revealed that the duration of symptoms and the frequency of hospitalization per year were significantly lower in the combination therapy than in both the Li-therapy and the CBZ-therapy. 3. In 7 out of 18 patients, the best prophylactic effect was obtained during combination therapy and none of the parameters measured was definitely inferior to those measured during the two single therapies. 4. During combination therapy, serum lithium level was significantly lower than during Li-therapy in the CBZ responders, and the combination of the two drugs enabled the required concentrations of lithium to be decreased. 5. It was concluded that synergistic action and a decrease in required concentrations of lithium can be expected with the combined use of lithium and CBZ, especially in responders to CBZ.