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PubMed1997

Elastin degradation by matrix metalloproteinases. Cleavage site specificity and mechanisms of elastolysis.

Insoluble elastin was used as a substrate to characterize the peptide bond specificities of human (HME) and mouse macrophage elastase (MME) and to compare these enzymes with other mammalian metalloproteinases and serine elastases. New amino termini detected by protein sequence analysis in insoluble elastin following proteolytic digestion reveal the P'1 residues in the carboxyl-terminal direction from the scissile bond. The relative proportion of each amino acid in this position reflects the proteolytic preference of the elastolytic enzyme. The predominant amino acids detected by protein sequence analysis following cleavage of insoluble elastin with HME, MME, and 92-kDa gelatinase were Leu, Ile, Ala, Gly, and Val. HME and MME were similar in their substrate specificity and showed a stronger preference for Leu/Ile than did the 92-kDa enzyme. Fibroblast collagenase showed no activity toward elastin. The amino acid residues detected in insoluble elastin following hydrolysis with porcine pancreatic elastase and human neutrophil elastase were predominantly Gly and Ala, with lesser amounts of Val, Phe, Ile, and Leu. There were interesting specificity differences between the two enzymes, however. For both the serine and matrix metalloproteinases, catalysis of peptide bond cleavage in insoluble elastin was characterized by temperature effects and water requirements typical of common enzyme-catalyzed reactions, even those involving soluble substrates. In contrast to what has been observed for collagen, the energy requirements for elastolysis were not extraordinary, consistent with cleavage sites in elastin being readily accessible to enzymatic attack.

Amino Acid Sequence↗
PubMed2006

Antimicrobial effect of mastic gum methanolic extract against Porphyromonas gingivalis.

The antimicrobial effect of mastic gum, an ancient remedy for oral malodor, against Porphyromonas gingivalis, a known odorogenic periopathogenic oral bacterium, was tested using the agar diffusion test. Paper discs impregnated with mastic gum methanolic extract (MME) [0.5-4% (wt/vol)] produced inhibition zones of 10.5-13.7 mm, respectively, without showing signs of hemolysis, whereas chlorhexidine (0.2%)-impregnated discs, which showed greater inhibition (33.5 mm), also produced large and distinctive hemolytic zones (17 mm). Further analysis of the antimicrobial traits of MME revealed a logarithmic ratio between inhibition zone diameter and MME concentration (r = .99), indicating limited water solubility of this material. These results suggest that mastic gum may be used as a potential nontoxic local agent in treating oral malodor and gum disease.

Anti-Infective Agents↗
PubMed1995

Arginine vasopressin stimulates protein synthesis but not proliferation of cultured vascular endothelial cells.

We previously showed that rat and cow blood vessels contain arginine vasopressin (AVP) of local origin. In the present study, to investigate potential roles for this locally produced peptide, we examined the effects of AVP on growth of cultured vascular endothelial and smooth muscle cells (EC, SMC). Treatment of cultured bovine aortic endothelial (BAE), murine cerebral microvascular endothelial (MME), or murine cerebral microvascular smooth muscle (MMSM) cells with AVP produced dose-dependent increases in total protein content with maximum increases of 11, 46, and 33% over vehicle-treated controls, respectively. AVP also dose-dependently increased new protein synthesis, as reflected by [3H]leucine incorporation into BAE and MME cell protein, with maximal increases of 34 and 24%, respectively. In addition, the AVP-stimulated increase in protein synthesis could be significantly attenuated in both BAE and MME cells by simultaneous addition of a specific AVP V1 receptor antagonist. In contrast, AVP did not affect total cell number or DNA synthesis, as reflected by [3H]thymidine incorporation, in any cell type. Neither was cell size, as measured by forward light scatter with a fluorescence-activated cell sorter (FACS), changed by treatment with AVP. However, the density of individual cells, as measured by orthogonal light scatter with FACS, was increased by AVP. These data demonstrate that AVP stimulates protein synthesis but not proliferation of cultured vascular EC and SMC and suggest that locally produced AVP may function as a growth factor for these cells.

Animals↗
PubMed1996

Characterization of soybean choline kinase cDNAs and their expression in yeast and Escherichia coli.

An expressed sequence tag from Arabidopsis that displayed sequence homology to mammalian and yeast choline kinases was used to isolate choline kinase-like cDNAs from soybean (Glycine max L.). Two distinct cDNAs, designated GmCK1 and GmCK2, were recovered that possessed full-length reading frames, each sharing approximately 32% identity at the predicted amino acid level with the rat choline kinase. A third unique choline kinase-like cDNA, GmCK3, was also identified but was not full length. Heterologous expression of GmCK1 in yeast (Saccharomyces cerevisiae) and GmCK2 in both yeast and Escherichia coli demonstrated that each encodes choline kinase activity. In addition to choline, other potential substrates for the choline kinase enzyme include ethanolamine, monomethylethanolamine (MME), and dimethylethanolamine (DME). Both soybean choline kinase isoforms demonstrated negligible ethanolamine kinase activity. Competitive inhibition assays, however, revealed very distinct differences in their responses to DME and MME. DME effectively inhibited only the GmCK2-encoded choline kinase activity. Although MME failed to effectively inhibit either reaction, an unexpected enhancement of choline kinase activity was observed specifically with the GmCK1-encoded enzyme. These results show that choline kinase is encoded by a small, multigene family in soybean comprising two or more distinct isoforms that exhibit both similarities and differences with regard to substrate specificity.

Amino Acid Sequence↗
PubMed1994

Poly(ethylene) glycol monomethyl ethers - an alternative to poly(ethylene) glycols in protein crystallization.

Poly(ethylene) glycol monomethyl ethers (Peg-mmes) are a series of methyl substituted poly(ethylene) glycols that have been used with some success in the crystallization of a number of hydrophobic proteins. Crystallization of a lipase from Humicola lanuginosa complexed with the C12 substrate analogue from Peg-mme 5000, an endoglucanase 1 and a 59 kDa fragment of human topoisomerase IIalpha crystallized from Peg-mme are described. The use of Peg-mme for improving the quality of crystals previously grown from normal poly(ethylene) glycol 8000 is also described. We suggest that these modified Peg-mmes should be regularly used in screening for crystallization.

Journal Article↗
PubMed1994

Immunological response in rabbits infested with Rhipicephalus sanguineus.

In order to clarify the importance of humoral antibody in host resistance to ticks, in the present work we studied the immunological response of rabbits infested with larvae, nymphs or adults of Rhipicephalus sanguineus, using extracts of eggs (EE), larvae (LE), nymphs (NE), male salivary glands (MSGE), male midguts (MME), female salivary glands (FSGE) and female midguts (FME). When serum from rabbits infested with larvae or nymphs was tested using enzyme-linked immunosorbent assay, no reactions were observed with any of the extracts including the homologous LE or NE. In sera from rabbits infested with adult ticks, the reactions were observed in both homologous (MSGE, MME, FSGE and FME) and heterologous (EE, LE and NE) system. However, differences were seen regarding the type of antigen used. When the experiment was carried out using extracts from adults higher responses were found. With FSGE and FME antigens, antibody levels were systematically higher than those observed when MSGE and MME were used.

Animals↗
PubMed1997

Requirement for macrophage elastase for cigarette smoke-induced emphysema in mice.

To determine which proteinases are responsible for the lung destruction characteristic of pulmonary emphysema, macrophage elastase-deficient (MME-/-) mice were subjected to cigarette smoke. In contrast to wild-type mice, MME-/- mice did not have increased numbers of macrophages in their lungs and did not develop emphysema in response to long-term exposure to cigarette smoke. Smoke-exposed MME-/- mice that received monthly intratracheal instillations of monocyte chemoattractant protein-1 showed accumulation of alveolar macrophages but did not develop air space enlargement. Thus, macrophage elastase is probably sufficient for the development of emphysema that results from chronic inhalation of cigarette smoke.

Animals↗
PubMed2005

Episomal maintenance of plasmids with hybrid origins in mouse cells.

Bovine papillomavirus type 1 (BPV1), Epstein-Barr virus (EBV), and human herpesvirus 8 genomes are stably maintained as episomes in dividing host cells during latent infection. The mitotic segregation/partitioning function of these episomes is dependent on single viral protein with specific DNA-binding activity and its multimeric binding sites in the viral genome. In this study we show that, in the presence of all essential viral trans factors, the segregation/partitioning elements from both BPV1 and EBV can provide the stable maintenance function to the mouse polyomavirus (PyV) core origin plasmids but fail to do so in the case of complete PyV origin. Our study is the first which follows BPV1 E2- and minichromosome maintenance element (MME)-dependent stable maintenance function with heterologous replication origins. In mouse fibroblast cell lines expressing PyV large T antigen (LT) and either BPV1 E2 or EBV EBNA1, the long-term episomal replication of plasmids carrying the PyV minimal origin together with the MME or family of repeats (FR) element can be monitored easily for 1 month under nonselective conditions. Our data demonstrate clearly that the PyV LT-dependent replication function and the segregation/partitioning function of the BPV1 or EBV are compatible in certain, but not all, configurations. The quantitative analysis indicates a loss rate of 6% per cell, doubling in the case of MME-dependent plasmids, and 13% in the case of FR-dependent plasmids in nonselective conditions. Our data clearly indicate that maintenance functions from different viruses are principally interexchangeable and can provide a segregation/partitioning function to different heterologous origins in a variety of cells.

Animals↗
PubMed2003

Membrane-bound diiron carboxylate proteins.

Four proteins have been identified recently as diiron carboxylate proteins on the basis of conservation of six amino acids (four carboxylate residues and two histidines) constituting an iron-binding motif. Unlike previously identified proteins with this motif, biochemical studies indicate that each of these proteins is membrane bound, although homology modeling rules out a transmembrane mode of binding. Therefore, the predicted structure of each protein [the alternative oxidase (AOX), the plastid terminal oxidase (PTOX), the diiron 5-demethoxyquinone hydroxylase (DMQ hydroxylase), and the aerobic Mg-protoporphyrin IX monomethylester hydroxylase (MME hydroxylase)] is that of a protein bound monotopically to one leaflet of the membrane bilayer. Three of these enzymes utilize a quinol substrate, with two oxidizing the quinol (AOX and PTOX) and one hydroxylating it (DMQ hydroxylase). MME hydroxylase is involved in synthesis of the isocyclic ring of chlorophyll. Two enzymes are involved in respiration (AOX and, indirectly, the diiron DMQ hydroxylase through ubiquinone biosynthesis) and two in photosynthesis, through their roles in carotenoid and chlorophyll biosynthesis (PTOX and MME hydroxylase, respectively). We discuss what is known about each enzyme as well as our expectations based on their identification as interfacially bound proteins with a diiron carboxylate active site.

Carboxylic Acids↗
PubMed1985

Asymmetric septal hypertrophy in uremic-normotensive patients on regular hemodialysis. An M-mode and two-dimensional echocardiographic study.

We have observed a high incidence (36.4%) of asymmetric septal hypertrophy (ASH), detected with the use of M-mode (MME) and two-dimensional echocardiography (2DE), in normotensive patients with chronic renal failure on maintenance hemodialysis without signs of cardiac diseases. ASH was detected by conventional MME in 11 cases and was confirmed with the use of 2DE in 8 cases showing a diagnostic concordance of 72.7% between the two methods. After dialysis the MME study of the left ventricular (LV) performance showed an evident impairment of cardiac index (CI) due to reduction of LV volume in addition to an abnormality of septal function. The presence of ASH does not impair the percentage of fractional shortening (FS%), the mean circumferential shortening (mean Vcf) and the ejection fraction (EF%), probably because of a compensatory performance of the LV posterior wall. Predialysis serum creatinine and fasting triglycerides have been found significantly higher in the group with ASH. ASH may be considered as a focal and early form of myocardial involvement in uremic patients on regular hemodialytic treatment.

Adult↗
PubMed1979

Two-dimensional echocardiographic demonstration of left atrial thrombi in patients with prosthetic mitral valves.

Although M-mode echocardiography (MME) is not a reliable method for detecting left atrial thrombi, recent reports suggest that two-dimensional echo (2DE) may be more effective than MME in identifying intracardiac thrombi. In three patients with prosthetic mitral valves who presented with either arterial embolization or prosthetic valvular dysfunction, 2DE demonstrated left atrial masses consistent with thrombi, while MME was either negative (two patients) or suspicious (one patient) for left atrial thrombus. Thrombi were documented by surgical or postmortem examination in all cases. Clear delineation of the atrial cavity and the margins of the masses, visualization on multiple echocardiographic views and comparison of serial examinations were helpful in identifying these masses as thrombi. In addition, the masses visualized had certain patterns of motion which seem unique and may allow characterization of atrial masses as thrombi.

Blood Coagulation↗
PubMed2005

Identification of a new neuropeptide precursor reveals a novel source of extrinsic modulation in the feeding system of Aplysia.

The Aplysia feeding system is advantageous for investigating the role of neuropeptides in behavioral plasticity. One family of Aplysia neuropeptides is the myomodulins (MMs), originally purified from one of the feeding muscles, the accessory radula closer (ARC). However, two MMs, MMc and MMe, are not encoded on the only known MM gene. Here, we identify MM gene 2 (MMG2), which encodes MMc and MMe and four new neuropeptides. We use matrix-assisted laser desorption/ionization time-of-flight mass spectrometry to verify that these novel MMG2-derived peptides (MMG2-DPs), as well as MMc and MMe, are synthesized from the precursor. Using antibodies against the MMG2-DPs, we demonstrate that neuronal processes that stain for MMG2-DPs are found in the buccal ganglion, which contains the feeding network, and in the buccal musculature including the ARC muscle. Surprisingly, however, no immunostaining is observed in buccal neurons including the ARC motoneurons. In situ hybridization reveals only few MMG2-expressing neurons that are mostly located in the pedal ganglion. Using immunohistochemical and electrophysiological techniques, we demonstrate that some of these pedal neurons project to the buccal ganglion and are the likely source of the MMG2-DP innervation of the feeding network and musculature. We show that the MMG2-DPs are bioactive both centrally and peripherally: they bias egestive feeding programs toward ingestive ones, and they modulate ARC muscle contractions. The multiple actions of the MMG2-DPs suggest that these peptides play a broad role in behavioral plasticity and that the pedal-buccal projection neurons that express them are a novel source of extrinsic modulation of the feeding system of Aplysia.

Amino Acid Sequence↗
PubMed2006

Assessing the responses of creek chub (Semotilus atromaculatus) and pearl dace (Semotilus margarita) to metal mine effluents using in situ artificial streams in Sudbury, Ontario, Canada.

Mining of the world's second-largest nickel deposits in the area of Sudbury, Ontario, Canada, has caused acidification and metal saturation of some catchments. We conducted artificial stream studies in the years 2001 and 2002 to assess the effects of treated metal mine effluents (MMEs) from three different mining operations discharging to Junction Creek, Sudbury, on two fish species, creek chub (Semotilus atromaculatus) and pearl dace (Semotilus margarita). Treatments tested for 35 to 41 d included reference water, Garson MME (30%), Nolin MME (20%), and Copper Cliff MME (45%). In 2001, effects on chub included reduced survival and depressed testosterone levels (fivefold reduction) after exposure to all MMEs. In 2002, chub and dace survival were reduced to less than 60% in the Copper Cliff and Garson treatments. In addition, the total body weights of male and female dace were reduced after exposure to the Garson and Copper Cliff treatments. In 2001 and 2002, responses were most common to the 45% Copper Cliff and 30% Garson effluents, with consistent increases in nickel, rubidium, strontium, iron, lithium, thallium, and selenium observed across treatment waters and body tissues. More work is required to link observed effects to field effects and to identify multitrophic level responses of the ecosystem to the MMEs. The artificial stream studies provided a mechanism to identify changes in the endpoints of relevant fish species exposed to present-day metal mine discharges independent of historical depositions of metals in the Sudbury area.

Animals↗
PubMedDate not supplied

[Psychiatric manifestations of vitamin B12 deficiency: a case report].

Psychiatric manifestations are frequently associated with pernicious anemia including depression, mania, psychosis, dementia. We report a case of a patient with vitamin B12 deficiency, who has presented severe depression with delusion and Capgras' syndrome, delusion with lability of mood and hypomania successively, during a period of two Months. Case report - Mme V., a 64-Year-old woman, was admitted to the hospital because of confusion. She had no history of psychiatric problems. She had history of diabetes, hypertension and femoral prosthesis. The red blood count revealed a normocytosis with anemia (hemoglobin=11,4 g/dl). At admission she was uncooperative, disoriented in time and presented memory and attention impairment and sleep disorders. She seemed sad and older than her real age. Facial expression and spontaneous movements were reduced, her speech and movements were very slow. She had depressed mood, guilt complex, incurability and devaluation impressions. She had a Capgras' syndrome and delusion of persecution. Her neurologic examination, cerebral scanner and EEG were postponed because of uncooperation. Further investigations confirmed anemia (hemoglobin=11,4 g/dl) and revealed vitamin B12 deficiency (52 pmol/l) and normal folate level. Antibodies to parietal cells were positive in the serum and antibodies to intrinsic factor were negative. An iron deficiency was associated (serum iron=7 micromol/l; serum ferritin concentration=24 mg/l; serum transferrin concentration=3,16 g/l). This association explained normocytocis anemia. Thyroid function, hepatic and renal tests, glycemia, TP, TCA, VS, VDRL-TPHA were normal. Vitamin B12 replacement therapy was started with hydroxycobalamin 1 000 ng/day im for 10 days and iron replacement therapy. Her mental state improved dramatically within a few days. After one week of treatment the only remaining symptoms were lability of mood, delusion of persecution, Capgras' syndrome but disappeared totally 9 days after the beginning of the treatment. A neurologic examination was possible because of cooperation. All the tendon reflexes of inferior members were absent. The plantars were in flexion and there was a left inferior member hypoesthesia. The cerebral scan and EEG were normal. Fundic biopsy, realized by fibroscopy, revealed fundic atrophia and intestinal metaplasia compatible with Biermers' disease. The iron deficiency exploration concluded diet deficiency. Mme V. appeared euphoric, her speech was very rapid with play on words and overactivity. This hypomania state totally disappeared 3 days after. Six Months after her hospitalisation, she presented an hypothyroidism (TSH=3,780; T3=1,35; T4=1,08). A thyroid hormones replacement was started and she continued to receive Monthly B12 replacement. Discussion - This case report illustrates psychiatric manifestations of Biermers' disease. The clinical arguments in favour are: white woman, more than 60 Years old, no history of psychiatric problems, atypical symptoms (confusional state with psychiatric symptoms), fluctuation of symptoms (severe depression with confusional state, delusion of persecution and Capgras' syndrome; delusion with lability of mood and hypomania), dramatic improvement after 9 days of vitamin B12 replacement therapy. The biological arguments are: anemia, vitamin B12 deficiency, normal folate level, atrophia and fundic metaplasia, positive antibodies to parietal cells in the serum, association between Biermers' disease and autoimmune disease (Haschimoto thyroidite). Psychiatric manifestations can occur in the presence of low serum B12 levels but in the absence of the other well recognized neurological and haematological abnormalities of pernicious anemia. Mental or psychological changes may precede haematological signs by Months or Years. They can be the initial symptoms or the only ones. Verbank et al. described the case of a patient with vitamin B12 deficiency in whom hypomania, paranoia and depression had been successively presented during a period of 5 Years before anemia have been developed. The case of Mme V. is similar in the succession of severe depression with delusion of persecution and Capgras' syndrome, delusion with lability of mood and hypomania, during a period of two Months. This report seems to be the first one of a sequence of several psychiatric states with pernicious anemia during a period of two Months with normocytosis anemia. To illustrate this illness we reviewed the literature regarding psychopathology associated with B12 deficiency. The most common psychiatric symptoms were depression, mania, psychotic symptoms, cognitive impairment and obsessive compulsive disorder. The neuropsychiatric severity by vitamin B12 deficiency and the therapeutic efficacy depends on the duration of signs and symptoms. Conclusion - We recommend consideration of B12 deficiency and serum B12 determinations in all the patients with organic mental disorders, atypical psychiatric symptoms and fluctuation of symptomatology. B12 levels should be evaluated with treatment resistant depressive disorders, dementia, psychosis or risk factors for malnutrition such as alcoholism or advancing age associated with neurological symptoms, anemia, malabsorption, gastrointestinal surgery, parasite infestation or strict vegetarian diet. In first intention, B12 deficiency should be researched by serum B12 determination (normal 200-950 pg/ml). Studies of methylmalonic acid and homocysteine showed that they are very sensitive functional indicators of cobalamin status especially when other evidence of cobalamin (B12) deficiency was equivocal. Measurement of methylmalonic acid (normal 73-271 nmol/l) and homocysteine (normal 5,4-13,9 micromol/l) should not replace the measurement of serum cobalamin.

Depression↗
PubMed1985

Lines of BPV-transformed murine cells that constitutively express influenza virus hemagglutinin.

We have developed and characterized several murine cell lines that constitutively express either the full-length, membrane-bound form of influenza virus hemagglutinin (HA) or a truncated version of the protein (HAsec) that lacks the carboxyterminal anchoring sequences and is secreted from cells. cDNAs encoding HA or HAsec were linked to the murine metallothionein-I promoter or the SV40 early promoter, and inserted into plasmids containing the transforming DNA fragment of bovine papilloma virus (BPV). The resulting vectors were introduced into three cultured lines of murine cells--C127, NIH3T3 and MME--either alone or in the presence of a plasmid that carries the aminoglycoside transferase gene of Tn5. The resulting lines of MME cells contained 1-5 copies of the vector in an integrated state and expressed low levels of HA (approximately 10(4) molecules/cell). In contrast, lines of C127 and NIH3T3 cells were obtained that express up to 5 X 10(6) molecules of HA per cell or secrete approximately 10(7) molecules of HAsec per cell per 24 h. Some of these cell lines carry multiple (30-200) copies of the vector in an integrated state; in others, the vector is propagated as unit-length episomes or as oligomers. Both the membrane-bound and secreted forms of HA expressed in these cell lines display a more extensive pattern of glycosylation than HA or HAsec synthesized in simian cells and they are transported to the cell surface more slowly. Pulse-chase experiments suggest that the step which limits the rate at which HA and HAsec travel down the secretory pathway occurs in the rough endoplasmic reticulum before the molecules are transferred to the Golgi apparatus. Using indirect immunofluorescence in combination with a cell sorter, we have shown that the level of expression of HA within cloned populations of producing cells can be variable. However, greater than 90% of the cells in certain cell lines display considerable quantities of HA on their surface, as judged by their ability to bind red blood cells in large numbers. We have taken advantage of the membrane fusion activity of HA to effect the fusion of erythrocytes to these cells and to deliver the contents of red cell ghosts into the cells' cytoplasm.

Animals↗
PubMed1991

Studies on the role of protein kinases in the TNF-mediated enhancement of murine tumor cell-endothelial cell interactions.

We have previously demonstrated that the exposure of mouse microvascular endothelium (MME) to tumor necrosis factor-alpha (TNF) led to the increased binding of mouse mastocytoma cells (P815) to endothelial monolayers (Bereta et al., in press). In the current study we examined the possible involvement of protein kinases in TNF signal transduction in the endothelial cells. PKA does not appear to play a role in the potentiation of binding by TNF. We found that the TNF-generated signal is inhibited by H-7 and sangivamycin, but not by staurosporine. TNF did not cause translocation of PKC to the cell membrane and its effect could not be completely mimicked by PMA nor by PMA in the presence of calcium-raising agents. Thus, we concluded that the "classical" PKC pathway is not completely responsible for TNF signalling in this system. We also found that staurosporine itself strongly enhanced adhesion of tumor cells to endothelium, utilizing a mechanism distinct from that of TNF. Although the data provide evidence for the role of kinases in the effect of TNF on binding of tumor cells to MME, this role appears to be a complex one.

Adenylyl Cyclases↗
PubMed1995

Differential regulation of p34cdc2 and p33cdk2 by transforming growth factor-beta 1 in murine mammary epithelial cells.

Cyclin-dependent kinases (cdks) are a family of proteins whose function plays a critical role in cell cycle traverse. Transforming growth factor-beta 1 (TGF-beta 1) is a potent growth inhibitor of epithelial cells. Since cdks have been suggested as possible biochemical markers for TGF-beta growth inhibition, we investigated the effect of TGF-beta 1 on cdc2 and cdk2 in a normal mouse mammary epithelial cell line (MME) and a TGF-beta-resistant MME cell line (BG18.2). TGF-beta 1 decreases newly synthesized cdc2 protein levels within 6 h after addition. Coincident with this decrease in newly synthesized cdc2 protein was a marked reduction in its ability to phosphorylate histone H1. This decrease in kinase activity is not due to a change in steady-state levels of cdc2 protein, since mRNA and total protein levels of cdc2 are not reduced until 12 h after TGF-beta 1 addition. This suggests that the kinase activity of cdc2 is dependent on newly synthesized cdc2 protein. Moreover, the protein synthesis of another cyclin-dependent kinase, cdk2, is not effected by TGF-beta 1 addition, but its kinase activity is substantially reduced. Thus, it appears that TGF-beta decreases the kinase activity of both cdc2 and cdk2 by distinct mechanisms.

Amino Acid Sequence↗
PubMed1995

Stimulation of glyceraldehyde-3-phosphate dehydrogenase mRNA levels by endogenous nitric oxide in cytokine-activated endothelium.

Previous studies have shown that endogenous nitric oxide (NO) potentiates glycolysis in the cytokine-activated murine microvascular endothelial cells (MME). In the present study we investigate the influence of NO on the expression of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), an enzyme of the glycolytic pathway. Activation of MME with TNF-alpha and IFN-gamma resulted in a strong elevation of GAPDH mRNA levels. This effect was impaired in the presence of L-NMMA, the inhibitor of NO synthesis. We discuss the possibility that NO-mediated elevation of GAPDH mRNA levels may compensate for NO-mediated inhibition of GAPDH enzymatic activity, representing another adaptive mechanism which protects cells producing large amounts of NO against its cytotoxic effects.

Animals↗