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H Zhou

Publications and source records attributed to H Zhou.

At least 163 records · Page 9Linked to original sources
PubMed2001

Mapping peroxidase in plant tissues by scanning electrochemical microscopy.

Scanning electrochemical microscopy has been firstly used to map the enzymatic activity in natural plant tissues. The peroxidase (POD) was maintained in its original state in the celery (Apium graveolens L.) tissues and electrochemically visualized under its native environment. Ferrocenemethanol (FMA) was selected as a mediator to probe the POD in celery tissues based on the fact that POD catalyzed the oxidation of FMA by H(2)O(2) to increase FMA(+) concentration. Two-dimensional reduction current profiles for FMA(+) produced images indicating the distribution and activity of the POD at the surface of the celery tissues. These images showed that the POD was widely distributed in the celery tissues, and larger amounts were found in some special regions such as the center of celery stem and around some vascular bundles.

Apium↗
PubMed2001

A systematic approach to the analysis of protein phosphorylation.

Reversible protein phosphorylation has been known for some time to control a wide range of biological functions and activities. Thus determination of the site(s) of protein phosphorylation has been an essential step in the analysis of the control of many biological systems. However, direct determination of individual phosphorylation sites occurring on phosphoproteins in vivo has been difficult to date, typically requiring the purification to homogeneity of the phosphoprotein of interest before analysis. Thus, there has been a substantial need for a more rapid and general method for the analysis of protein phosphorylation in complex protein mixtures. Here we describe such an approach to protein phosphorylation analysis. It consists of three steps: (1) selective phosphopeptide isolation from a peptide mixture via a sequence of chemical reactions, (2) phosphopeptide analysis by automated liquid chromatography-tandem mass spectrometry (LC-MS/MS), and (3) identification of the phosphoprotein and the phosphorylated residue(s) by correlation of tandem mass spectrometric data with sequence databases. By utilizing various phosphoprotein standards and a whole yeast cell lysate, we demonstrate that the method is equally applicable to serine-, threonine- and tyrosine-phosphorylated proteins, and is capable of selectively isolating and identifying phosphopeptides present in a highly complex peptide mixture.

Amino Acid Sequence↗
PubMed2001

Quantitative profiling of differentiation-induced microsomal proteins using isotope-coded affinity tags and mass spectrometry.

An approach to the systematic identification and quantification of the proteins contained in the microsomal fraction of cells is described. It consists of three steps: (1) preparation of microsomal fractions from cells or tissues representing different states; (2) covalent tagging of the proteins with isotope-coded affinity tag (ICAT) reagents followed by proteolysis of the combined labeled protein samples; and (3) isolation, identification, and quantification of the tagged peptides by multidimensional chromatography, automated tandem mass spectrometry, and computational analysis of the obtained data. The method was used to identify and determine the ratios of abundance of each of 491 proteins contained in the microsomal fractions of naïve and in vitro- differentiated human myeloid leukemia (HL-60) cells. The method and the new software tools to support it are well suited to the large-scale, quantitative analysis of membrane proteins and other classes of proteins that have been refractory to standard proteomics technology.

Affinity Labels↗
PubMed2001

An integrated electrochemical capillary liquid chromatography-dual microelectrode system for bromine based reaction detection.

Amperometric reaction detection of model peptides containing either a thiol or disulfide was successfully achieved with a novel coupled capillary liquid chromatography-dual microelectrode system. Detection is facilitated via dual platinum wire electrodes fabricated directly on a liquid chromatography capillary column. The detection strategy is based on the electrogeneration of bromine at the upstream working electrode followed by reduction of the bromine to bromide at the downstream working electrode. When bromine reacts with analyte eluting from the capillary column, the amount of bromine that reaches the downstream electrode decreases. As a result, the current at the downstream electrode will decrease in proportion to the amount of analyte eluting from the capillary column. Glutathione, glutathione disulfide, alpha-TGF and oxytocin were used to characterize the system and to determine system parameters. The feasibility of the determination of disulfide containing peptides is demonstrated with glutathione disulfide, alpha-TGF and oxytocin.

Bromine↗
PubMed2001

C-Terminal region of human NAD+-dependent 15-hydroxyprostaglandin dehydrogenase is involved in the interaction with prostaglandin substrates.

NAD+-dependent 15-hydroxyprostaglandin dehydrogenase (15-PGDH) catalyzes the oxidation of the 15(S) hydroxyl group of prostaglandins to a 15-keto group resulting in a significant reduction of the biological activities of prostaglandins. Although the key residues involved in NAD+ binding and in catalytic activity have been partially identified, the sites of interaction of the enzyme with the prostaglandin substrates are yet to be determined. Homology analysis of the primary structures of 15-PGDH from human, mouse and rat indicates that the sequences are almost homologous except for two regions near the C-terminus. The involvement of the C-terminal region in catalytic activity was examined by studies on C-terminally truncated enzymes and on human/rat chimeric enzymes. When three to four amino acids were removed successively from the C-terminal end of human 15-PGDH, the truncated enzymes exhibited decreasing Vmax/Km ratios and increasing Km values for PGE2 as the chain was shortened. Similarly, when the C-terminal 14 amino acids of human 15-PGDH were replaced by the C-terminal 14 amino acids of rat 15-PGDH or vice versa, the Vmax/Km ratios and the Km values for prostaglandin E2 of the chimeric enzymes were in between those of the two wild-type enzymes. This indicates that the catalytic effectiveness of human 15-PGDH decreases as the C-terminal region is gradually removed or replaced by rat sequences. The C-terminal region appears to be more important for the interaction of the enzyme with the prostaglandin substrates than with the coenzyme.

Amino Acid Sequence↗
PubMed2001

Ultrasound assessment of scald scars in Asian children receiving pressure garment therapy.

BACKGROUND/PURPOSE: Scar formation after scald injury in children is managed commonly by application of pressure garment. The duration of the treatment depends on clinical assessment. The objective of the study was to evaluate the efficacy of the pressure garment therapy and to correlate the clinical assessment scar thickness with ultrasound measurement. METHODS: Prospective study of children with hypertrophic scars receiving pressure garment therapy was carried out between 1993 and 1998. The scars were mapped with paper cutting. Representative scar sites were scored clinically according to Vancouver General Hospital Burn Assessment Scale (pigmentation, vascularity, pliability, height, pain, itchiness). Blind to the clinical results, 2 radiologists measured the scar thickness of the same sites with ultrasonography (5 to 10 MHz transducer, General Electric LOGIQ 500). The correlation between the clinical scores and ultrasound measurement of scar thickness were analysed using analysis of variance (ANOVA). RESULTS: The median age of 58 children with scald injury (M:F = 36:22) was 2.8 years (0.5 to 15.8 years). The mean percentage of scald was 8.8% (24% had scald area >10%). In addition, there were 5 children with burn from naked flame and 9 children with keloid secondary to surgical incisions. With pressure garment therapy, the scar thickness reached a plateau 1 (1/2) years after the injury and began to decline gradually thereafter. The clinical estimation of scar thickness correlated well with the ultrasound measurement (ANOVA, P =.003, Adjusted R square = 0.99). The accuracy rate of clinical thickness estimation was 67%. Overestimation and underestimation accounted for 15% and 18%, respectively. There also was good correlation between total clinical score and the ultrasound measurement (ANOVA, P <.001). CONCLUSIONS: In children with scald injury, the pressure garment needs to be continued for a minimum of 1 year. Ultrasound measurement correlates well with overall score of the Vancouver General Hospital Burn Assessment Scale but not individual components of the scoring system except wound height.

Adolescent↗
PubMed2001

A prospective study of a one-week nonbismuth quadruple therapy for childhood Helicobacter pylori infection.

PURPOSE: In the eradication of Helicobacter pylori infection, a 1-week therapy improves patient compliance, but drug resistance may limit its efficacy. The effectiveness of the 1-week nonbismuth quadruple therapy was studied prospectively in children with proven H pylori infection in a population with a high rate of metronidazole resistance. METHODS: All pediatric patients who presented to our institutions with acute and chronic upper gastrointestinal conditions requiring endoscopy from June 1997 to February 2000 were investigated prospectively for H pylori infection. Gastric biopsy specimens were analyzed with rapid urease test and histopathology, H pylori-positive children were treated with omeprazole, clarithromycin, amoxicillin, and metronidazole for 7 days. The result of treatment was assessed 1 month after treatment with endoscopy and biopsy. The same treatment was repeated for 2 weeks if H pylori was still present. In patients who needed a third endoscopy, their biopsy specimens were cultured to determine antibiotic sensitivity. Results were correlated with patients' symptoms and endoscopic findings. RESULTS: Thirty-three children with acute (severe epigastric pain, n = 14; gastrointestinal bleeding, n = 9) and chronic (recurrent abdominal pain, n = 7; anemia, n = 3) conditions were treated for H pylori. Thirty-one (94%) were confirmed to have H pylori eradicated by a 1-week therapy, whereas 1 patient had eradication after a further 2-we'ek therapy (3.3%). The only unresponsive patient had H pylori resistant to both clarithromycin and metronidazole. All ulcers and erosions healed after the eradication of H pylori. Three patients had persistent recurrent abdominal pain despite H pylori eradication. CONCLUSIONS: The 1-week therapy with omeprazole, clarithromycin, amoxicillin, and metronidazole is an effective treatment of H pylori in children in a population with a high incidence of metronidazole resistant strain of H pylori. Peptic ulcers and erosions healed with the eradication of the bacteria.

Adolescent↗
PubMed2001

Disturbed expression of Fas/FasL on CD4(+) and CD8(+)T cells in Behcet's disease, Vogt-Koyanagi-Harada syndrome, and idiopathic anterior uveitis.

AIMS: To evaluate the expression of Fas/FasL antigen on peripheral blood T lymphocytes in patients with Behcet's disease, Vogt-Koyanagi-Harada (VKH) syndrome, and idiopathic anterior uveitis. METHODS: The expression of Fas and FasL on peripheral blood T lymphocytes was determined using flow cytometry in 26 patients with Behcet's disease (BD), 17 patients with VKH syndrome, 25 patients with idiopathic anterior uveitis, and 43 healthy individuals (controls). RESULTS: A higher proportion of CD4(+) T cells expressing Fas was noted in patients with Behcet's disease (25.70 +/- 7.32%), VKH syndrome (19.60 +/- 11.02%), and idiopathic anterior uveitis (20.81+/- 7.40%) compared with controls (14.02 +/- 6.30%). The expression of Fas on CD8(+) cells from patients with Behcet's disease (9.47 +/- 6.97%) and VKH syndrome (6.84+/- 5.5%) was also higher than that seen in controls (3.47+/- 2.75%). There was no difference in FasL expression on T cells between patients and controls except that a lower expression of FasL on CD8(+) T cells was noted in patients with idiopathic anterior uveitis. CONCLUSION: A disturbed expression of Fas and FasL on T cells is present in patients with Behcet's disease, VKH syndrome, and idiopathic anterior uveitis, which may be involved in the perpetuation and recurrence of uveitis.

Adult↗
PubMed2001

Pharmaceutical cost-containment policy: experiences in Shanghai, China.

BACKGROUND: In the decade after 1983, the annual growth rate of drug expenditure was about four times as high as that of per capita gross domestic product (GDP) in Shanghai. In 1993 and 1994, a drug list policy and hospital revenue capping policy were introduced in Shanghai to contain drug expenditure. We studied the impact of these two policies, as a model for similar policies in other parts of China and elsewhere. METHODS: Quarterly drug expenditure data were collected from 1992 to 1996 and more detailed drug expenditure flow was obtained at seven selected hospitals. Twelve focus group discussions were organized to obtain opinions from all stakeholders. RESULTS: The research findings showed a dramatic and continuing decline in the growth rates of total medical and drug expenditures after the implementation of the two policies. The proportion of total medical expenditure attributable to drugs declined from 67% in 1992 to 51% in 1996. The annual growth rate of drug expenditure per ambulatory visit and per bed-day was reduced as well. Drug revenue as a proportion of total hospital revenue declined gradually in all seven hospitals. The two policies did not alter the equity of drug utilization between the insured and non-insured. The government, insurance authority and state-owned drug enterprises all favoured the new policies, while hospital administrators, professionals, joint venture and foreign manufacturers wished for the reimbursement mechanisms to be improved, for retention of their freedom of choice, and for the drug list to be further expanded. CONCLUSIONS: The drug list and capping policies in Shanghai appear to have achieved their objectives of containing the escalation of drug expenditure and improving the rational use of drugs without loss of equity. The underlying causes of the escalation of drug expenditure in China need to be further elucidated.

Ambulatory Care↗
PubMed2001

Candidate gene promoter polymorphisms and antibody response kinetics in chickens: interferon-gamma, interleukin-2, and immunoglobulin light chain.

An F2 population was produced from mating G0 highly inbred (>99%) males of two MHC-congenic Fayoumi lines with G-B1 Leghorn hens. The F2 population was essentially a full-sibship with the F1 sire line reflecting MHC effect. Adult F2 hens (n = 158) were injected twice with SRBC and whole fixed Brucella abortus (BA). Agglutinating antibody titer at 7 d after primary immunization and mean titer of the final three samples (Days 18, 32, and 63 after the second immunization) were used as parameters for primary and equilibrium phases, respectively. Secondary phase parameters of minimum (Ymin), maximum titers (Ymax) and time needed to achieve minimum (Tmin) and maximum (Tmax) titers were estimated from seven postsecondary titers with a nonlinear regression model. Three candidate genes, interferon-gamma (IFN-gamma), interleukin-2 (IL-2), and immunoglobulin G light chain (IgL) were studied. Primers for the promoter regions were designed from EMBL chicken genomic sequences. Polymorphisms between parental lines were detected by direct sequencing. Polymerase chain reaction-restriction fragment length polymorphism methods were then developed to directly detect the polymorphism. There were significant main effects (P < 0.05, general linear model analysis) of IFN-gamma polymorphism on Ymax of BA antibody and interaction of IFN-gamma by IgL on primary antibody response to SRBC and BA, and on Tmin and Ymin of antibody response to SRBC in F2 offspring of M5.1 grandsires. There were significant main effects of IFN-gamma polymorphism on Tmax of BA and interaction of IFN-gamma by IL-2 on Ymin to SRBC in F2 offspring of M15.2 grandsires. The results suggest that IFN-gamma genes play an important role in chicken primary and secondary antibody response to SRBC and BA antigens, and there exists interaction among genes for antibody production.

Agglutination Tests↗
PubMed2001

Genetic variation among chicken lines and mammalian species in specific genes.

Thirteen gene-specific primer sets provided by the U.S. Poultry Genome Coordinators were used to investigate DNA polymorphisms between two highly inbred chicken lines of Leghorn and Fayoumi origin. Nucleotide and predicted amino acid sequences were then compared among these chicken lines and the Genbank sequences of chicken, mouse, and human. The following genes were selected as candidates for immune response or transcription activation: B2M, DAD1, IAP1, IL2, IREB1, LAP18, MAFL, POU1F1, RREB1, TAD, TBP1, TCRG, and ZOV3. Total cDNA was obtained from the spleens of Leghorn and Fayoumi lines by reverse transcriptase-polymerase chain reaction (PCR) and was used as a template to PCR-amplify gene-specific products. All primers except POU1F1 and TCRG generated single PCR products of the predicted 325- to 667-bp size, confirming the efficacy of these gene-specific primers in the chicken. Three and seven of the 11 amplified gene fragments yielded line-specific nucleotide polymorphisms between the Leghorn and Fayoumi sequences and between the Leghorn and Genbank chicken sequences respectively. Similarities between inbred Leghorn and mammalian species were 36 to 86% for nucleotides and 25 to 96% for predicted amino acid sequence. The polymorphisms of some gene fragments between the Leghorn and Fayoumi lines will allow for investigation of associations of these genes with immune response and other biological traits.

Amino Acid Sequence↗
PubMed2001

Are myogenin and myoD1 expression specific for rhabdomyosarcoma? A study of 150 cases, with emphasis on spindle cell mimics.

Rhabdomyosarcoma (RMS), the most common soft tissue sarcoma of childhood, displays a variety of histologic patterns. Immunohistochemistry is used extensively to distinguish RMS from its mimics. Myogenin and MyoD1, myogenic transcriptional regulatory proteins expressed early in skeletal muscle differentiation, are considered sensitive and specific markers for RMS and are more specific than desmin and muscle-specific actin and more sensitive than myoglobin. Previous studies have focused on expression of myogenin and MyoD1 in small round cell tumors. This study assesses myogenin and MyoD1 in rhabdomyosarcoma subtypes and spindle cell tumors considered in the differential diagnosis of RMS. Formalin-fixed, paraffin-embedded archival tissue from 32 RMS, 107 non-RMS, and 11 benign skeletal muscle samples was stained for myogenin and MyoD1 with standard immunohistochemical techniques. Nuclear positivity was scored on a three-tiered scale. All RMSs expressed myogenin. Alveolar RMS (ARMS) showed strong nuclear staining, especially in tumor cells lining fibrous septae and perivascular regions. In cases with a subtle alveolar architecture on routinely stained sections, myogenin highlighted and enhanced visualization of the alveolar morphologic pattern. Embryonal RMSs (ERMSs) were more variable in myogenin staining pattern and intensity. No cases of nodular fasciitis, malignant fibrous histiocytoma, malignant peripheral nerve sheath tumor, inflammatory myofibroblastic tumor, myofibrosarcoma, leiomyoma, leiomyosarcoma, or alveolar soft part sarcoma stained for myogenin. Focal nuclear reactivity was seen in desmoid (2 of 10), infantile myofibromatosis (2 of 10), synovial sarcoma (1 of 10), and infantile fibrosarcoma (2 of 10). Non-neoplastic skeletal muscle fiber nuclei stained positively for myogenin in both tumor-associated samples (25 of 40) and benign skeletal muscle samples (5 of 11). Although all RMSs were immunoreactive for MyoD1, cytoplasmic and nonspecific background staining and reactivity of nonmyoid tissues hindered its practical utility in paraffin-embedded samples in this study. Although myogenin is a highly sensitive and specific marker for RMS, it is rarely seen in other spindle cell soft tissue tumors. As previously reported, ARMS stained more strongly than ERMS. In contrast to previous studies, rare non-RMS (7 of 107) displayed focal nuclear reactivity, and entrapped atrophic or regenerative skeletal muscle fibers also stained positively. Although these are potential pitfalls in the interpretation of myogenin, careful attention to morphology and other features, to the relative paucity of myogenin-positive nuclei in non-RMS. and to the presence of entrapped muscle fibers should prevent incorrect interpretation. Because the extent of myogenin expression in RMS is much greater than in non-RMS, it is a very useful marker when interpreted in the context of other clinicopathologic data.

Biomarkers, Tumor↗
PubMed2001

Smoking and pregnancy outcome among African-American and white women in central North Carolina.

Despite extensive research on tobacco smoking during pregnancy, few studies address risks among African-American and white women, groups that differ in brand preference and smoking habits. The Pregnancy, Infection, and Nutrition Study is a prospective cohort study that included 2,418 women with detailed information on smoking during pregnancy, including brand, number of cigarettes per day, and changes during pregnancy. We analyzed risk of preterm birth (<37 and <34 weeks' gestation) and small-for-gestational-age deliveries in relation to tobacco use. Pregnant African-American smokers differed markedly from whites in brand preference (95% vs 26% smoked menthol cigarettes) and number of cigarettes per day (1% of African-Americans and 12% of whites smoked 20+ cigarettes per day). Smoking was not related to risk of preterm birth overall, but cotinine measured at the time of delivery was (adjusted odds ratio = 2.2, 95% confidence interval = 1.1-4.5). A clear association and dose-response gradient was present for risk of fetal growth restriction (risk ratio for 20+ cigarettes/day = 2.4, 95% confidence interval = 1.4-4.0). Associations of tobacco use with preterm premature rupture of amniotic membrane resulting in preterm birth were notably stronger than the associations with other types of preterm birth.

Black or African American↗
PubMed2001

Endothelial cells enhance human immunodeficiency virus type 1 replication in macrophages through a C/EBP-dependent mechanism.

Macrophages are early targets of human immunodeficiency virus type 1 (HIV-1) infection and serve as potential reservoirs for long-term infection. Through inflammatory mediators and direct cell contact, infected macrophages interact with neighboring cell populations, such as the endothelium, which create a microenvironment favorable for HIV-1 replication. We hypothesize that the transcriptional activator C/EBPbeta is critical for macrophages to respond to endothelial cell-derived signals. We show that endothelial cells significantly enhance C/EBPbeta binding activity and HIV-1 replication in macrophages. This increase in HIV-1 transcription is due to cell-cell contact as well as the production of soluble factors, mediated in part by ICAM-1 and interleukin 6, respectively. Furthermore, C/EBP factors are necessary for endothelial cell-dependent activation of HIV-1 transcription in macrophages, and HIV-1 induction can be inhibited by a C/EBP dominant-negative protein. In addition, C/EBP binding sites are necessary for efficient LTR activity and HIV-1 replication in the presence of endothelial cells. Taken together, these results indicate that endothelial cells, through the activation of C/EBPbeta, provide a microenvironment that supports HIV-1 replication in monocytes/macrophages.

CCAAT-Enhancer-Binding Protein-beta↗
PubMed2001

Substrate sequence selection by retroviral integrase.

Integration of retrovirus DNA is a specific process catalyzed by the integrase protein acting to join the viral substrate DNA (att) sequences of about 10 bases at the ends of the long terminal repeat (LTR) to various sites in the host target cell DNA. Although the interaction is sequence specific, the att sequences of different retroviruses are largely unrelated to one another and usually differ between the two ends of the viral DNA. To define substrate sequence specificity, we designed an "in vitro evolution" scheme to select an optimal substrate sequence by competitive integration in vitro from a large pool of partially randomized substrates. Integrated substrates are enriched by PCR amplification and then regenerated and subjected to subsequent cycles of selection and enrichment. Using this approach, we obtained the optimal substrate sequence of 5'-ACGACAACA-3' for avian sarcoma-leukosis virus (ASLV) and 5'-AACA(A/C)AGCA-3' for human immunodeficiency virus type 1, which differed from those found at both ends of the viral DNA. Clonal analysis of the integration products showed that ASLV integrase can use a wide variety of substrate sequences in vitro, although the consensus sequence was identical to the selected sequence. By a competition assay, the selected nucleotide at position 4 improved the in vitro integration efficiency over that of the wild-type sequence. Viral mutants bearing the optimal sequence replicated at wild-type levels, with the exception of some mutations disrupting the U5 RNA secondary structure important for reverse transcription, which were significantly impaired. Thus, maximizing the efficiency of integration may not be of major importance for efficient retrovirus replication.

Alpharetrovirus↗
PubMed2001

Her4 mediates ligand-dependent antiproliferative and differentiation responses in human breast cancer cells.

The function of the epidermal growth factor receptor (EGFR) family member HER4 remains unclear because its activating ligand, heregulin, results in either proliferation or differentiation. This variable response may stem from the range of signals generated by HER4 homodimers versus heterodimeric complexes with other EGFR family members. The ratio of homo- and heterodimeric complexes may be influenced both by a cell's EGFR family member expression profile and by the ligand or even ligand isoform used. To define the role of HER4 in mediating antiproliferative and differentiation responses, human breast cancer cell lines were screened for responses to heregulin. Only cells that expressed HER4 exhibited heregulin-dependent antiproliferative responses. In-depth studies of one line, SUM44, demonstrated that the antiproliferative and differentiation responses correlated with HER4 activation and were abolished by stable expression of a kinase-inactive HER4. HB-EGF, a HER4-specific ligand in this EGFR-negative cell line, also induced an antiproliferative response. Moreover, introduction and stable expression of HER4 in HER4-negative SUM102 cells resulted in the acquisition of a heregulin-dependent antiproliferative response, associated with increases in markers of differentiation. The role of HER2 in these heregulin-dependent responses was examined through elimination of cell surface HER2 signaling by stable expression of a single-chain anti-HER2 antibody that sequestered HER2 in the endoplasmic reticulum. In the cell lines with either endogenously (SUM44) or exogenously (SUM102) expressed HER4, elimination of HER2 did not alter HER4-dependent decreases in cell growth. These results suggest that HER4 is both necessary and sufficient to trigger an antiproliferative response in human breast cancer cells.

Breast Neoplasms↗
PubMed2001

Sequential activation of heterotrimeric and monomeric G proteins mediates PLD activity in smooth muscle.

The identity of G proteins mediating CCK-stimulated phospholipase D (PLD) activity was determined in intestinal smooth muscle cells. CCK-8 activated G(q/11), G(13), and G(12), and the monomeric G proteins Ras-homology protein (RhoA) and ADP ribosylation factor (ARF). Activation of RhoA, but not ARF, was mediated by G(13) and inhibited by Galpha(13) antibody. CCK-stimulated PLD activity was partly mediated by RhoA and could be inhibited to the same extent (47 +/- 2% to 53 +/- 6%) by 1) a dominant negative RhoA mutant, 2) RhoA antibody or Galpha(13) antibody, and 3) Clostridium botulinum C3 exoenzyme. PLD activity was also inhibited by ARF antibody, and the effect was additive to that of RhoA antibody or C3 exoenzyme. PLD activity was inhibited by calphostin C, bisindolylmaleimide I, and a selective protein kinase C (PKC)-alpha inhibitor; the inhibition was additive to that of ARF and RhoA antibodies and C3 exoenzyme. In contrast, activated G(12) was not coupled to RhoA or ARF, and Galpha(12) antibody augmented PLD activity. Thus agonist-stimulated PLD activity is mediated additively by G(13)-dependent RhoA and by ARF and PKC-alpha and is modulated by an inhibitory G(12)-dependent pathway.

ADP Ribose Transferases↗