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Biomedical subjects

L Song

Publications and source records attributed to L Song.

At least 19 recordsLinked to original sources

Bisindolylmaleimide VIII facilitates Fas-mediated apoptosis and inhibits T cell-mediated autoimmune diseases.

Fas-mediated apoptosis is essential for the elimination of cells, and impaired apoptosis can have severe detrimental consequences. Bisindolylmaleimide VIII potentiated Fas-mediated apoptosis in human astrocytoma 1321N1 cells and in Molt-4T cells, both of which were devoid of apoptosis induced by anti-Fas antibody in the absence of bisindolylmaleimide VIII, and in Jurkat and CEM-6 T cells, which showed slight and moderate apoptotic responses, respectively, to low levels of Fas stimulation. Potentiation of Fas-mediated apoptosis by bisindolylmaleimide VIII was selective for activated, rather than non-activated, T cells, and was Fas-dependent, as it was not observed in T cells from Fas-deficient lpr/lpr mice. Administration of bisindolylmaleimide VIII to rats during autoantigen stimulation prevented the development of symptoms of T cell-mediated autoimmune diseases in two models, the Lewis rat model of experimental allergic encephalitis and the Lewis adjuvant arthritis model. Thus, the use of agents such as bisindolylmaleimide VIII may be therapeutically useful for supporting more effective elimination of detrimental cells through enhancement of Fas-dependent apoptosis signaling.

Animals

Production of gelatinases and tissue inhibitors of matrix metalloproteinases by equine ovarian stromal cells In vitro.

Matrix metalloproteinases (MMPs) and tissue inhibitors of MMPs (TIMPs) play very important roles in extracellular matrix (ECM) remodeling in ovarian follicle growth and ovulation. Equine follicles are embedded in cortex that is at the center of the ovary, and they must expand/emigrate to the fossa, the only site in the ovary for ovulation. Therefore, equine ovarian stromal cells (EOSC) are probably involved in ECM remodeling during follicle growth. This study examined whether cultured EOSC synthesize gelatinases and TIMPs, molecules essential for ECM remodeling in other systems. Results showed that cultured EOSC (passage 3-8) had a fibroblast-like morphology and were positive for alpha-smooth muscle actin and type I procollagen by immunostaining. Gelatinase A (MMP-2), gelatinase B (MMP-9), TIMP-1, and TIMP-2 were present in EOSC-conditioned medium, and TIMP-3 in ECM of EOSC. Transforming growth factor beta significantly stimulated the activity of gelatinases A and B and TIMP-1 in conditioned medium from EOSC (p < 0.05). Phorbol 12-myristate 13-acetate also significantly stimulated the activity of gelatinases A and B and TIMP-1 in conditioned medium and of TIMP-3 in ECM (p < 0.05). Our results suggest that EOSC produce important components of the ECM remodeling machinery and, therefore, may play a role in the ECM remodeling during follicle growth in this species.

Animals

Kidney aminopeptidase A and hypertension, part I: spontaneously hypertensive rats.

Tissue and plasma levels of aminopeptidase A (APA), the principal enzyme that hydrolyzes angiotensin II (Ang II) to angiotensin III, were measured in spontaneously hypertensive rats (SHR) and their normotensive control strain at 3 different ages corresponding to prehypertensive (4 weeks), developing (8 weeks), and established (16 weeks) phases of hypertension. Plasma APA activity was significantly but modestly elevated in SHR at all 3 ages compared with normotensive Wistar-Kyoto rats. Likewise, levels of APA in brain, heart, and adrenal gland were generally, but again only moderately, elevated in SHR at all ages. However, a large increase in APA activity was seen within the kidney in which APA levels were elevated 41%, 51%, and 68% in SHR at 4, 8, and 16 weeks of age, respectively. Kidney APA levels were also significantly increased in immunoblots from 8- and 16-week-old SHR. Glomeruli isolated from 16-week-old SHR had 57% higher APA activity and increased immunoreactivity compared with Wistar-Kyoto rats. To determine whether the increase in kidney APA activity in SHR was related to Ang II levels, SHR were treated for 2 weeks with the angiotensin-converting enzyme inhibitor captopril. Captopril treatment reduced blood pressure to normotensive values and resulted in a 25% reduction in kidney APA activity. These results suggest that APA expression in the kidney may be regulated by activity of the renin-angiotensin system. If so, this would further suggest that upregulation of APA during conditions in which Ang II levels were elevated would have a protective effect against Ang II-mediated cardiovascular diseases, whereas a decrease in APA expression or a failure to upregulate would exacerbate such conditions.

Aminopeptidases

Kidney aminopeptidase A and hypertension, part II: effects of angiotensin II.

Aminopeptidase A (APA) is the principal enzyme that metabolizes angiotensin II (Ang II) to angiotensin III. Previously, we showed that kidney APA was elevated in spontaneously hypertensive rats and was reduced after angiotensin-converting enzyme inhibition. In the present study, we sought to determine whether kidney APA expression was altered after chronically elevated Ang II, either exogenously delivered via osmotic minipumps or endogenously produced in two-kidney, one clip (2K1C) hypertensive rats. Ang II (200 ng. kg-1. min-1) was infused subcutaneously for 1 or 2 weeks by osmotic minipumps, and 2K1C rats were tested 4 weeks after unilateral renal artery clipping. Blood pressure was not significantly elevated in the Ang II-infused animals but was significantly increased at 3 and 4 weeks in the 2K1C animals. APA was significantly elevated approximately 2-fold in kidney cortical membranes from Ang II-infused animals but was decreased 45% in the clipped kidney and 18% in the nonclipped kidneys from 2K1C animals. Isolated glomeruli from Ang II-infused animals and the nonclipped kidneys from 2K1C animals had markedly higher APA activity and immunoreactivity. Likewise, histochemical and immunohistochemical studies indicated that APA levels were increased in glomeruli from angiotensin-infused animals and in both nonclipped and clipped kidneys from 2K1C animals. In contrast, tubular APA was decreased in tubular elements from 2K1C animals, most markedly in the clipped kidneys. Thus, despite the increase in glomerular APA expression in kidneys from 2K1C animals, the decrease in tubular APA expression is more extensive and accounts for the measured reduction in total APA in cortical homogenates. Because clipped kidneys are not exposed to high blood pressure, these results suggest that glomerular APA expression is positively regulated and tubular APA negatively regulated by Ang II. These results further suggest that changes in kidney APA expression could influence the progression of angiotensin-dependent hypertension.

Aminopeptidases

Peroxynitrite modulates tyrosine phosphorylation and phosphoinositide signalling in human neuroblastoma SH-SY5Y cells: attenuated effects in human 1321N1 astrocytoma cells.

Peroxynitrite may contribute to oxidative stress involving neurodegeneration in several disorders, including Alzheimer's disease. As with other reactive oxygen species, peroxynitrite might affect neuronal signalling systems, actions that could contribute to adaptive or deleterious cellular outcomes, but such effects have not previously been studied. To address this issue directly, peroxynitrite (50-500 microM) was administered to human neuroblastoma SH-SY5Y cells to assess its effects on protein tyrosine nitration, phosphoinositide signalling and protein tyrosine phosphorylation. Peroxynitrite rapidly increased the nitrotyrosine immunoreactivity of numerous proteins, primarily in the cytosol. Peroxynitrite inhibited, in a concentration-dependent manner, phosphoinositide hydrolysis stimulated by activation of muscarinic receptors with carbachol and the inhibition was greater after the depletion of cellular glutathione. In comparison, muscarinic receptor-stimulated phosphoinositide hydrolysis in human astrocytoma 1321N1 cells was less vulnerable to inhibition by peroxynitrite either without or with prior depletion of glutathione. There was a large, rapid and reversible increase in the tyrosine phosphorylation of the p120 Src substrate in peroxynitrite-treated SH-SY5Y cells, a response that was potentiated by glutathione depletion; in contrast, peroxynitrite decreased the tyrosine phosphorylation of focal adhesion kinase and paxillin. Tyrosine phosphorylation of p120 in 1321N1 astrocytoma cells was less sensitive to modulation by peroxynitrite. Thus alterations in phosphoinositide signalling and protein tyrosine phosphorylation were greater in neuroblastoma than astrocytoma cells, and modulation of these signalling processes probably contributes to neuronal mechanisms of the response to peroxynitrite.

Astrocytoma

Thin slice CNS explants maintained on collagen-coated culture dishes.

We have developed a simple and inexpensive procedure for explant culture termed 'thin slice culture' that relies on the use of thin sections of CNS tissue ( < or = 150 microm) which adhere directly to the bottom of collagen-coated culture dishes (or glass coverslips within culture dishes). Microscopic visualization and tissue oxygenation are enhanced due to the reduced slice thickness, and the reduced volumes of incubation media required lessen the amount of expensive agents used (e.g. growth factors). We show that thin slice cultures of spinal cord, brainstem and hippocampus remain viable for at least several weeks and are suitable for many experimental approaches including time-dependent studies, immunocytochemistry and electrophysiology.

Animals

Crystallization of the alpha-hemolysin heptamer solubilized in decyldimethyl- and decyldiethylphosphine oxide.

Crystals of the alpha-hemolysin heptamer, a transmembrane pore-forming toxin from Staphylococcus aureus, have been grown using the nonionic detergents n-decyldimethyl- and n-decyldiethylphosphine oxide, phosphorus homologs of the ionic amine oxide detergents. Five crystal forms were obtained, one of which diffracted X-rays to 3 A resolution. This crystal form displayed elements of pseudo mm symmetry in screened precession photographs yet it was triclinic with unit-cell dimensions a = 173, b = 173, c = 102 A, alpha = 92.6, beta = 94.8, gamma = 90.2 degrees.

Bacterial Toxins

Glutathione depletion exacerbates impairment by oxidative stress of phosphoinositide hydrolysis, AP-1, and NF-kappaB activation by cholinergic stimulation.

Oxidative stress appears to contribute to neuronal dysfunction associated with Alzheimer's disease and other CNS neurodegenerative disorders. This investigation examined if oxidative stress might contribute to impairments in cholinergic receptor-linked signaling systems and if intracellular glutathione levels modulated responses to oxidative stress. To do this the activation of the AP-1 and NF-kappaB transcription factors and of the phosphoinositide second-messenger system was measured in human neuroblastoma SH-SY5Y cells after exposure to the oxidants H2O2 or diamide, with or without prior depletion of cellular glutathione. H2O2 concentration-dependently inhibited carbachol-stimulated AP-1 activation and this inhibition was potentiated in glutathione-depleted cells. Carbachol-stimulated NF-kappaB activation was unaffected by H2O2 unless glutathione was depleted, in which case there was a H2O2 concentration-dependent inhibition. Glutathione depletion also potentiated the inhibition by H2O2 of carbachol- or G-protein (NaF)-stimulated phosphoinositide hydrolysis, whereas phospholipase C activated by the calcium ionophore ionomycin was not inhibited. The thiol-oxidizing agent diamide also inhibited phosphoinositide hydrolysis stimulated by carbachol or NaF, and glutathione depletion potentiated the diamide concentration-dependent inhibition. Unlike H2O2, diamide also inhibited ionomycin-stimulated phosphoinositide hydrolysis. Activation of both AP-1 and NF-kappaB stimulated by carbachol was inhibited by diamide, and glutathione depletion potentiated the inhibitory effects of diamide. Thus, diamide inhibited a wider range of signaling processes than did H2O2, but glutathione depletion increased the susceptibility of phosphoinositide hydrolysis and of transcription factor activation to inhibition by both H2O2 and diamide. These results demonstrate that the vulnerability of signaling systems to oxidative stress is influenced by intracellular glutathione levels, indicating that cell-selective susceptibility to inhibition of signal transduction systems by oxidative stress can arise from cellular variations in antioxidant capacity.

Analysis of Variance

Breast cancer rescreening in low-income women.

INTRODUCTION: Routine mammography screening with clinical breast examination is effective in reducing breast cancer mortality. The Breast and Cervical Health Program (BCHP) in Washington State provides free breast and cervical cancer screening for low-income women, with an emphasis on women of color. This study examined initial breast cancer rescreening and factors associated with rescreening for women enrolled in BCHP in King County, Washington. METHODS: Data were obtained from the Washington State BCHP tracking system. We estimated the percentages who received breast cancer rescreening for women enrolled between July 1994 and December 1995 using survival analysis. Cox proportional regression was also used to examine factors associated with time-until-rescreening. RESULTS: Survival analysis showed that the overall percentages rescreened at 15 and 27 months for women aged 50-69 were 25.7% and 45.0%, respectively. For women aged 40-49, the corresponding percentages were 26.0% and 40.3%. Rescreening differed by age groups, race/ethnicity, level of education, foreign born status, history of previous mammography, and enrollment clinic. CONCLUSIONS: Results from this study suggested that in addition to initial efforts for enrollment, screening programs should emphasize increased rescreening especially for women with certain demographic and screening history characteristics.

Adult

Selective increases in phosphoinositide signaling activity and G protein levels in postmortem brain from subjects with schizophrenia or alcohol dependence.

Comparisons of the activity of the G protein-mediated phosphoinositide signal transduction system and of G protein levels were made in two regions of frontal cortex from eight schizophrenic, alcohol-dependent, and control subjects. G protein-mediated phosphoinositide hydrolysis was measured by stimulating cortical membranes incubated with [3H]phosphatidylinositol with 0.3-10 microM guanosine 5'-O-(3-thio)triphosphate (GTPgammaS). In frontal cortex areas 8/9, GTPgammaS-induced phosphoinositide hydrolysis was 50% greater in schizophrenic than control or alcohol-dependent subjects, whereas there were no differences among these groups of subjects in the response to GTPgammaS in frontal cortex area 10. Agonists for dopaminergic, cholinergic, purinergic, serotonergic, histaminergic, and glutamatergic receptors coupled to the phosphoinositide signaling system increased [3H]phosphatidylinositol hydrolysis in a GTPgammaS-dependent manner. Responses to most agonists were similar in all three subject groups in both cortical regions, with the largest difference being a 40% greater response to dopaminergic receptor stimulation in frontal cortex 8/9 from schizophrenic subjects. Measurements of the levels of phospholipase C-beta, and of alpha-subunits of Gq, Go, Gi1, Gi2, and Gs, made by immunoblot analyses revealed no differences among the groups of subjects except for increased G alpha(o) in schizophrenic subjects and increased G alpha(o) and G alpha(i1) in alcohol-dependent subjects. These results demonstrate that schizophrenia is associated with increased activity of the phosphoinositide signal transduction system and increased levels of G alpha(o), whereas the phosphoinositide system was unaltered in alcohol dependence, but G alpha(o) and G alpha(i1) were increased.

Adult

Analysis of common mutations and associated haplotypes in Chinese patients with glucose-6-phosphate dehydrogenase deficiency.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a rare disease in North China. In the present investigation, DNA samples from 17 patients with G6PD deficiency from Tianjin area in North China were studied for the two G6PD common mutations (R459L and R463H) and two single nucleotide polymorphisms (1311C/T and 1365-13T/C) using a dideoxy fingerprinting method. Five patients were positive for mutation R459L, and six patients were positive for mutation R463H. Further haplotype analyses using three flanking dinucleotide repeat polymorphism loci, DXS1123, DXS1113, and F8C(IVS13), were performed on 14 patient families and 16 control Chinese females. The results indicated that the two common mutations were from different haplotypes. Also, the data suggested a possible allelic association between the two G6PD common mutations and the F8C(IVS13) locus and a different allelic distribution for loci DXS1113 and F8C(IVS13) between Chinese and Caucasian populations.

Amino Acid Substitution

The mouse H19 locus mediates a transition between imprinted and non-imprinted DNA replication patterns.

Genes subject to genomic imprinting generally occur in clusters of hundreds of kilobases. These domains exhibit several gamete of origin-dependent manifestations, including a pattern of asynchronous replication when studied by fluorescence in situ hybridization (FISH). We find a transition from asynchronous replication at the imprinted mouse H19 gene to synchronous replication at the downstream Rpl23 gene, the human homologue of which appears to be non-imprinted. Two-colour FISH demonstrates that this transition is due solely to a difference in replication timing between the upstream and downstream chromatin on the later-replicating (maternal) chromosome. This difference is lost in mice deleted for the H19 gene body and 9.9 kb of upstream DNA when this deletion is maternally inherited, with synchronous replication patterns extending over 110 kb upstream from the deleted area. No effect is seen when the deletion is paternally inherited. The presence of a boundary element in this region has been suggested by observations of position-independent expression of H19 -containing transgenes and the blocking of accessibility of downstream enhancers to the upstream Igf2 and Ins2 genes on the maternal chromosome. The FISH studies presented here demonstrate the insulation of replication patterns within the imprinted domain from downstream, non-imprinted chromatin, mediated by an element at the H19 locus which is subject to genomic imprinting.

Animals

Biomechanical evaluation of titanium, biodegradable plate and screw, and cyanoacrylate glue fixation systems in craniofacial surgery.

Choice of appropriate fixation after reduction of displaced bone fragments or advancement of osteotomized segments requires knowledge of the maximal force to which these segments can be subjected. The present study was performed to obtain a biomechanical comparison of a variety of resorbable fixation systems as an alternative to metal plates and screws. Sheep cadaver parietal bone segments were osteotomized and fixed with one of six methods of fixation: (A) titanium plates and screws consisting of (1) miniplates and 2.0-mm-diameter screws; (2) midface plates and 1.5-mm screws; (3) microplates and 1.0-mm screws; (B) resorbable systems consisting of combinations of butyl-2-cyanoacrylate glue and biodegradable polylactic acid/polyglycolic acid copolymer plates and 2.0-mm screws as follows: (1) direct glue fixation of segments; (2) resorbable plates fixed to bone segments with cyanoacrylate glue; (3) resorbable plates fixed with resorbable screws. Compression testing was performed upon bone segments advanced and fixed across a central gap, and distraction testing was performed on bone segments fixed in direct contact. Force to failure in both distraction and compression was significantly greater in bone segments fixed with titanium miniplates than with any other method of fixation. Segments fixed with plates and screws, either nonresorbable or resorbable, achieved stronger fixation in distraction than in compression for all plate sizes tested. Resorbable plate and screw fixation was as strong as standard titanium midface and microplating systems in distraction, and stronger than the latter techniques in compression. With compressive forces of relapse, fixation with glue and resorbable plates was as strong as standard titanium midface and microplating systems. However, with distractive forces of relapse, glue fixation of either the bone segments or resorbable plates was weaker than both titanium and resorbable alternatives in which plates and screws were used. These findings may have direct impact on the choice of fixation devices used to support osteotomized or fractured bone segments, which are subjected to persistent muscular and soft-tissue pull.

Animals

Biomechanical and histologic alteration of facial recipient bone after reconstruction with autogenous bone grafts and alloplastic implants: a 1-year study.

Potential alteration of the underlying recipient bone resulting from a graft or implant has significant clinical relevance. The present study was designed to evaluate the biomechanical and histologic alteration of facial recipient bone with autogenous bone graft and alloplastic implants over a 1-year period. The bilateral arches of 15 rabbits were randomized between four groups: (1) control (n = 6), subperiosteal exposure of the zygomatic arch was made; (2) onlay (n = 12), bone graft was placed as an onlay to the zygomatic arch; (3) inlay (n = 6), bone graft was placed as an inlay within the zygomatic arch; (4) implant (n = 6), a stainless steel plate was placed as an onlay to the zygomatic arch. Animals were killed 1 year after grafting. In the onlay groups, all steel implants and half of the onlay bone grafts (n = 6) were separated from the zygomatic arch; the remaining onlay bone grafts (n = 6) were left on the zygomatic arch. Three-point breaking strength was measured through the center of the graft/implant site on the zygomatic arch, followed by histologic evaluation and histometric assessment of residual bone density. The findings demonstrated no difference in the breaking strength per unit bone area between the control zygomatic arch group and the onlay group in which the bone graft was left in place. Breaking strength of the zygomatic arch in the former two groups was significantly greater than that in either group in which the onlay bone graft or implant had been removed, and was also greater than the breaking strength in that group in which inlay bone had been placed (p < 0.05). Histologic assessment showed full-thickness conversion in architecture of the zygomatic arch from compact to woven bone beneath onlays of either autogenous bone graft or steel implant; histometric assessment demonstrated an accompanying decrease in bone density in the latter groups relative to the control zygoma (p < 0.05). We conclude that onlay autogenous bone graft and alloplastic implants to the facial skeleton induce transformation of both graft and recipient bone from compact to woven architecture, accompanied by a reduction in bone density. The biomechanical strength of recipient facial bone is significantly weakened if an onlay bone graft or implant is removed. Weakening occurs per unit area of remaining bone, and is therefore independent of any thinning that may occur within the recipient bone because of graft/implant placement. These findings may impact upon decisions to augment stress-bearing regions of the facial skeleton with bone graft or implants, particularly if the graft/implant may eventually require removal.

Animals

Kinetic alterations of angiotensin-II and nitric oxide in radiation pulmonary fibrosis.

We studied the kinetic alterations of angiotensin-II (A-II) and nitric oxide (NO) in radiation pulmonary fibrosis (RPF) to determine the roles of these two types of vasoactive substances in the pathogenesis of RPF. We irradiated the right hemithorax of male Wistar rats with single doses of 0, 15, and 30 Gy of 60Co gamma rays and we examined the lung parenchyma at 1, 3, 5, and 7 months following the radiation. The rats were killed at the stated intervals and samples were obtained from the right lung. We measured types I and III procollagen mRNA by in situ hybridization and demonstrated the synthesis and distribution of A-II in the pulmonary tissue by immunohistochemistry. The formation and kinetic alterations of types I and III collagen were analyzed under polarized light microscope using Sirius Red stain. The hydroxyproline (Hyp) content was measured in the pulmonary tissue after digestion with HCl. A-II radiation immunoactivity (RIA) was assayed in pulmonary tissue homogenate. Pulmonary NO content, NO synthase (NOS), and the angiotensin converting enzyme (ACE) activities were also measured. Our results showed that types I and III collagen genes began to be expressed 1 month after irradiation. Type I collagen gene increased significantly, reaching its peak 3 months after irradiation. As the irradiation dosage was increased from 15 to 30 Gy, the type I collagen gene content increased significantly, while type III significantly decreased. The Hyp content increased with the passage of time after irradiation. Pulmonary A-II RIA increased significantly with the dose of irradiation and was chiefly produced by fibroblasts and macrophages in the interstitium, bronchiolar epithelium, and the anteriolar wall. Pulmonary NO and NOS activities decreased following irradiation. One month following irradiation, the expression of the type I collagen gene begins to increase, with a significant increase in both Hyp and type I collagen 3 months after irradiation. The histogenesis of RPF may be related to A-II. The interstitial cells, the bronchiolar epithelium, and the arteriolar wall can produce A-II and need not pass through the ACE pathway. Our results suggest that the A-II increase and NO decrease may have a role in the pathogenesis of RPF.

Angiotensin II

The protective action of taurine and L-arginine in radiation pulmonary fibrosis.

Taurine has the ability to resist the action of oxygen-free radicals by protecting cytomembranes. L-arginine increases the nitric oxide in the organism, inhibiting some types of abnormal cell proliferation. We examined the actions and protective mechanisms of these two substances against radiation pulmonary fibrosis. The mRNA transcription and the distribution of pulmonary types I and III procollagen were measured by in situ hybridization. Type I and type III collagen in the interalveolar septa and the change ratio between the two types were assayed using Sirius Red staining and polarizing microscopy. Angiotensin converting enzyme (ACE), hydroxyproline (Hyp), malondialdehyde (MDA), and nitric oxide (NO) were measured in lung tissue after irradiation. We found that, following administration of taurine or arginine, the mRNA transcription of procollagen types I and III significantly decreased in the pulmonary tissue 3 months after irradiation and the Hyp content was lower, especially after the administration of arginine. The extent of the radiation-induced decrease in ACE activity was markedly attenuated. As a substrate of NO production, arginine can significantly increase the pulmonary NO content. We conclude that the administration of taurine or arginine can significantly decrease the mRNA transcription of procollagen and the synthesis of type I collagen in the interalveolar septa and can decrease the Hyp content of the pulmonary tissue. Following irradiation, NO can attenuate the radiation-induced decrease in ACE activity. Our study suggests that exogenous NO and taurine significantly protect against radiation pulmonary injury.

Animals

AP-1 and NF-kappaB stimulated by carbachol in human neuroblastoma SH-SY5Y cells are differentially sensitive to inhibition by lithium.

In order to identify potential actions of lithium, the primary therapeutic agent for bipolar affective disorder, on processes regulating gene expression, its effects on two transcription factors, AP-1 and NF-kappaB, were measured in human neuroblastoma SH-SY5Y cells. The cholinergic agonist carbachol concentration-dependently stimulated AP-1 (EC50 = 2 microM) and NF-kappaB (EC50 = 14 microM). Pretreatment for 24 h with a therapeutically relevant concentration of lithium (1 mM) substantially inhibited (30-35%) carbachol-stimulation AP-1 but not NF-kappaB. Inhibition of carbachol-induced AP-1 was directly related to the concentration of lithium (1-20 mM). Besides being differentially sensitive to inhibition by lithium, activation of AP-1 and NF-kappaB demonstrated different carbachol EC50 concentrations, and carbachol-induced activation of AP-1, but not NF-kappaB, was inhibited by treating cells with Ni2+, which blocks receptor-mediated calcium influx. These findings demonstrate that one mechanism by which lithium can influence the expression of specific genes is through the selective modulation of signaling processes which emanate from cholinergic receptor stimulation.

Carbachol

Cloning and expression of human carboxypeptidase Z, a novel metallocarboxypeptidase.

A novel cDNA, designated carboxypeptidase Z (CPZ), was identified based on its homology to known metallocarboxypeptidases. Northern blot analysis shows bands of 2.1 and/or 2.6 kilobases in all tissues examined. The major form of CPZ mRNA in human salivary gland encodes a protein with an open reading frame of 641 amino acids. In addition, three variants were found that presumably arise due to alternative intron splicing. The 641-amino acid protein contains an 18-residue signal peptide-like sequence, a 120-residue region that shows 23-29% amino acid identity with a Cys-rich domain found in frizzled proteins and in type XVIII collagen, and then a 390-residue carboxypeptidase domain with 49% amino acid identity to carboxypeptidases E and N. The 641-amino acid form of CPZ expressed in the baculovirus system cleaves 5-dimethylaminonaphthalene-1-sulfonyl (dansyl)-Phe-Ala-Arg, although the level of enzyme activity was approximately 10-fold lower than either carboxypeptidase E or D expressed using the same viral system. The CPZ activity is more active at neutral pH than at pH 5.5 and is inhibited by active site-directed inhibitors of metallocarboxypeptidases. In summary, CPZ is a novel metallocarboxypeptidase that is active toward substrates with C-terminal basic amino acids.

Amino Acid Sequence