Silicon nanowire FET biosensor and its application in acute myocardial infarction

Over the last two decades, silicon nanowire field-effect transistors (SiNW-FETs) with prominent merits of high surface-to-volume ratio, excellent biocompatibility and mature fabrication with standard silicon technology, have been widely studied as ultrahigh sensitive biosensors for the detection of target biomolecules, such as proteins, nucleic acids, cells and viruses so on. Herein we present a comprehensive review of the fundamental aspects of SiNW-FET biosensors, involving the working principle and the device fabrication, surface functionalization, and system integration with fluid exchange and electrical detection. Futhermore, we emphatically discuss the electrical detection of cardiac-specific biomarkers related to acute myocardial infarction disease. SiNW-FET biosensors are being increasingly exploited as promising diagnostic devices, which provide high sensitivity, high integration density, high speed sampling, strong specificity, and real-time and label-free detection for simple and cheap clinical testing.

Examining the Efficacy and Safety Profile of Palliative Radiotherapy Using 30 Gy in 5 Fractions

PURPOSE/OBJECTIVE(S)

Higher biological equivalent doses of radiotherapy (RT) can improve symptom palliation and local control in select tumor sites. However, not all patients meet criteria for treatment with stereotactic ablative radiotherapy (SABR). Furthermore, SABR is a resource intensive technique which may limit its use in many centers. The 30 Gray in 5 fractions regimen (30/5) stems from a modification of 5-fraction SABR regimens. It is a conformal, homogenous hypo-fractionated regimen that delivers higher dose than conventional palliative RT while still respecting the normal tissue constraints for 5-fraction SABR. It uses streamlined contouring and planning with less stringent requirements for immobilization and image guidance, compared to what is required for SABR. This study evaluates the clinical outcomes of patients receiving 30/5.

MATERIALS/METHODS

A single institution retrospective review of clinical and treatment data was performed for patients who received 30/5 from October 2020 to August 2022. Local control (LC) was calculated for all treatment courses. Distant metastasis-free survival (DMFS), progression-free survival (PFS), and overall survival (OS) were calculated for all patients. Survival analyses were analyzed by the Kaplan-Meier method and curves compared by log-rank test. Univariate and multivariate analyses were performed using cox-regression analysis.

RESULTS

A total of 77 patients and 92 courses of 30/5 were available for analysis. The most common primary tumor was lung (44%), followed by gastrointestinal (GI; 20%), breast (10%), and genitourinary (10%). The median age of patients was 64 years (range: 37-93). The median tumor size treated was 11.4 cm^3 (range: 0.3 - 210.9 cm^3). Treatment sites included lung (31%), lymph nodes (22%), non-spine bone (20%), and spine (15%). At median follow-up of 10.1 months (mo), 25 deaths occurred. Median LC after receiving 30/5 was 18.5 mo (95% CI: 15.7-21.3 mo), median DMFS was 6.6 months (95% CI: 4.6-8.6 mo), median PFS was 6.4 mo (95% CI: 4.9-8.0 mo), and median OS was 18.1 mo (95% CI: 13.1-23.1 mo). Median time to initiating, restarting, or changing systemic therapy was 12.8 mo (95% CI: 7.6-18.0 mo). Radiosensitive (lung, prostate, breast, gynecological, and head/neck) tumors had better LC than radioresistant (GI, renal cell, sarcoma, melanoma) tumors (median 20.9 vs 12.1 mo, p < 0.02). Six grade 2 toxicities occurred (6.5% of all treatments). No grade 3 or higher toxicities occurred.

CONCLUSION

The 30/5 regimen is a safe, well-tolerated, and resource efficient regimen with effective local control. This may serve as a practical alternative for patients who require palliative RT but not optimal candidates for SABR. As expected, radiosensitive tumors had better local control than radioresistant tumors. Future research can further explore the safety, efficacy, and indications of 30/5 as a palliative RT option.

RAPid SimPLE (RAPPLE) Targeted Radiation Treatment vs. Whole Brain Radiotherapy: A Retrospective Study of Matched Patients with Brain Metastases and Poor Prognosis

PURPOSE/OBJECTIVE(S)

Patients with brain metastases and poor prognosis are often treated with whole brain radiotherapy (WBRT) which can cause a variety of side effects. Our institution devised a new brain-sparing radiotherapy technique to treat multiple brain metastasis for patients whose poor prognosis does not warrant SRS. This study compares the oncologic outcomes of matched patients treated with RAPPLE and WBRT.

MATERIALS/METHODS

RAPPLE uses single-isocenter, coplanar volumetric modulated arc therapy and a non-stereotactic head-shell with IntegraBite™. Brain metastasis were contoured in a single gross tumor volume and expanded by 3 mm to create a planning target volume, of which 99.5% was covered with 95-110% of 20 Gy in 5 fractions. Patients treated with a first course of RAPPLE from January 2017 to December 2021 were identified in an institutional database. Using age, cancer diagnosis, and treatment date, we identified a matched cohort of patients receiving a first course of WBRT with 20 Gy in 5 fractions. Overall survival (OS) was calculated using the Kaplan-Meier method, and intracranial progression was calculated using cumulative incidence with a competing risk of death. Log-rank, Cox regression and Fine-Gray analyses were used for comparisons. Paired t-tests were used to compare patient-reported fatigue measured using 5-level Likert scales before and 2-6 weeks after radiotherapy.

RESULTS

The RAPPLE and WBRT cohorts each had 137 patients. The matched median age was 69 years. Primary diagnoses were lung cancer (72%) and other cancers (28%). The minimum, median, and maximum numbers of metastases treated with RAPPLE were 1, 3, and 18, respectively. The median Karnofsky Performance Score (KPS) was 70 in both cohorts. The median survival was 4.1 months for RAPPLE and 4.2 months for WBRT, and the 18-month OS was 11% for RAPPLE and 12% for WBRT (log-rank p = 0.8). On multivariable analysis, KPS, diagnosis, extracranial disease, and use of systemic therapy before and after RT were predictive of OS, but use of RAPPLE vs. WBRT was not (HR = 0.97, 95% CI: 0.75-1.25, p = 0.8). The 18-month cumulative incidence of intracranial progression was 0.49 for RAPPLE and 0.37 for WBRT (p = 0.04). After RAPPLE, 17% required more focal RT and 4% required salvage WBRT, while after WBRT, 3% required focal RT and 4% required repeat WBRT. After RAPPLE, mean patient-reported fatigue remained stable from baseline to first follow-up (2.18 vs. 2.27, p = 0.9), but, after WBRT, it worsened from baseline to first follow-up (1.95 vs. 2.63, p = 0.002).

CONCLUSION

As expected, after RAPPLE, more targeted radiotherapy was required for intracranial progression, but there was no difference in OS between the RAPPLE and WBRT cohorts. Patients reported significantly worse fatigue after WBRT. Almost all patients (96%) treated with RAPPLE avoided WBRT.

POS0851 IDENTIFICATION OF HUB GENES AND PATHWAYS IN DERMATOMYOSITIS BY BIOINFORMATICS ANALYSIS

Background:

Dermatomyositis (DM) is a chronic systemic autoimmune disease characterized by inflammatory infiltrates in the skin and muscle1. The genes and pathways in the inflamed myopathies in patients with DM are poorly understood2.

Objectives:

To identify the key genes and pathways associated with DM and further discover its pathogenesis.

Methods:

Muscle tissue gene expression profile (GSE143323) were acquired from the GEO database, which included 39 DM samples and 20 normal samples. The differentially expressed genes (DEGs) in DM muscle tissue were screened by adopting the R software. Gene ontology (GO) and Kyoto Encyclopedia of Genome (KEGG) pathway enrichment analysis was performed by Metascape online analysis tool. A protein-protein interaction (PPI) network was then constructed by STRING software using the genes in significantly different pathways. Network of DEGs was analyzed by Cytoscape software. And degree of nodes was used to screen key genes.

Results:

Totally, 126 DEGs were obtained, which contained 122 up-regulated and 4 down-regulated. GO analysis revealed that most of the DEGs were significantly enriched in type I interferon signaling pathway, response to interferon-gamma, collagen-containing extracellular matrix, response to interferon-alpha and bacterium, positive regulation of cell death, leukocyte chemotaxis. KEGG pathway analysis showed that upregulated DEGs enhanced pathways associated with the hepatitis C, complement and coagulation cascades, p53 signaling pathway, RIG-I-like receptor signaling, Osteoclast differentiation, and AGE-RAGE signaling pathway. Ten hub genes were identified in DM, they were ISG15, IRF7, STAT1, MX1, OASL, OAS2, OAS1, OAS3, GBP1, and IRF9 according to the Cytoscape software and cytoHubba plugin.

Conclusion:

The findings from this bioinformatics network analysis study identified the key hub genes that might provide new molecular markers for its diagnosis and treatment.

References:

[1]Olazagasti JM, Niewold TB, Reed AM. Immunological biomarkers in dermatomyositis. Curr Rheumatol Rep 2015;17(11):68. doi: 10.1007/s11926-015-0543-y [published Online First: 2015/09/26].

[2]Chen LY, Cui ZL, Hua FC, et al. Bioinformatics analysis of gene expression profiles of dermatomyositis. Mol Med Rep 2016;14(4):3785-90. doi: 10.3892/mmr.2016.5703 [published Online First: 2016/09/08].

[3]Zhou Y, Zhou B, Pache L, et al. Metascape provides a biologist-oriented resource for the analysis of systems-level datasets. Nat Commun 2019;10(1):1523. doi: 10.1038/s41467-019-09234-6 [published Online First: 2019/04/05].

Acknowledgements:

This project was supported by National Science Foundation of China (82001740), Open Fund from the Key Laboratory of Cellular Physiology (Shanxi Medical University) (KLCP2019) and Innovation Plan for Postgraduate Education in Shanxi Province (2020BY078).

Disclosure of Interests:

None declared

POS0458 IDENTIFICATION OF HUB GENES AND MOLECULAR PATHWAYS IN PATIENTS WITH RHEUMATOID ARTHRITIS BY BIOINFORMATICS ANALYSIS

Background:

Rheumatoid arthritis (RA) is a chronic, inflammatory synovitis based systemic disease of unknown etiology1. The genes and pathways in the inflamed synovium of RA patients are poorly understood.

Objectives:

This study aims to identify differentially expressed genes (DEGs) associated with the progression of synovitis in RA using bioinformatics analysis and explore its pathogenesis2.

Methods:

RA expression profile microarray data GSE89408 were acquired from the public gene chip database (GEO), including 152 synovial tissue samples from RA and 28 healthy synovial tissue samples. The DEGs of RA synovial tissues were screened by adopting the R software. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were performed. Protein-protein interaction (PPI) networks were assembled with Cytoscape software.

Results:

A total of 654 DEGs (268 up-regulated genes and 386 down-regulated genes) were obtained by the differential analysis. The GO enrichment results showed that the up-regulated genes were significantly enriched in the biological processes of myeloid leukocyte activation, cellular response to interferon-gamma and immune response-regulating signaling pathway, and the down-regulated genes were significantly enriched in the biological processes of extracellular matrix, retinoid metabolic process and regulation of lipid metabolic process. The KEGG annotation showed the up-regulated genes mainly participated in the staphylococcus aureus infection, chemokine signaling pathway, lysosome signaling pathway and the down-regulated genes mainly participated in the PPAR signaling pathway, AMPK signaling pathway, ECM-receptor interaction and so on. The 9 hub genes (PTPRC, TLR2, tyrobp, CTSS, CCL2, CCR5, B2M, fcgr1a and PPBP) were obtained based on the String database model by using the Cytoscape software and cytoHubba plugin3.

Conclusion:

The findings identified the molecular mechanisms and the key hub genes of pathogenesis and progression of RA.

References:

[1]Xiong Y, Mi BB, Liu MF, et al. Bioinformatics Analysis and Identification of Genes and Molecular Pathways Involved in Synovial Inflammation in Rheumatoid Arthritis. Med Sci Monit 2019;25:2246-56. doi: 10.12659/MSM.915451 [published Online First: 2019/03/28]

[2]Mun S, Lee J, Park A, et al. Proteomics Approach for the Discovery of Rheumatoid Arthritis Biomarkers Using Mass Spectrometry. Int J Mol Sci 2019;20(18) doi: 10.3390/ijms20184368 [published Online First: 2019/09/08]

[3]Zhu N, Hou J, Wu Y, et al. Identification of key genes in rheumatoid arthritis and osteoarthritis based on bioinformatics analysis. Medicine (Baltimore) 2018;97(22):e10997. doi: 10.1097/MD.0000000000010997 [published Online First: 2018/06/01]

Acknowledgements:

This project was supported by National Science Foundation of China (82001740), Open Fund from the Key Laboratory of Cellular Physiology (Shanxi Medical University) (KLCP2019) and Innovation Plan for Postgraduate Education in Shanxi Province (2020BY078).

Disclosure of Interests:

None declared

AB0005 IDENTIFICATION OF KEY GENES AND PATHWAYS FOR PSORIASIS BASED ON GEO DATABASES BY BIOINFORMATICS ANALYSIS

Background:

Psoriasis is an immune-mediated, genetic disease manifesting in the skin or joints or both, and also has a strong genetic predisposition and autoimmune pathogenic traits1. The hallmark of psoriasis is sustained inflammation that leads to uncontrolled keratinocyte proliferation and dysfunctional differentiation. And it’s also a chronic relapsing disease, which often necessitates a long-term therapy2.

Objectives:

To investigate the molecular mechanisms of psoriasis and find the potential gene targets for diagnosis and treating psoriasis.

Methods:

Total 334 gene expression data of patients with psoriasis research (GSE13355 GSE14905 and GSE30999) were obtained from the Gene Expression Omnibus database. After data preprocessing and screening of differentially expressed genes (DEGs) by R software. Online toll Metascape3 was used to analyze Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of DEGs. Interactions of proteins encoded by DEGs were discovered by Protein-protein interaction network (PPI) using STRING online software. Cytoscape software was utilized to visualize PPI and the degree of each DEGs was obtained by analyzing the topological structure of the PPI network.

Results:

A total of 611 DEGs were found to be differentially expressed in psoriasis. GO analysis revealed that up-regulated DEGs were mostly associated with defense and response to external stimulus while down-regulated DEGs were mostly associated with metabolism and synthesis of lipids. KEGG enrichment analysis suggested they were mainly enriched in IL-17 signaling, Toll-like receptor signaling and PPAR signaling pathways, Cytokine-cytokine receptor interaction and lipid metabolism. In addition, top 9 key genes (CXCL10, OASL, IFIT1, IFIT3, RSAD2, MX1, OAS1, IFI44 and OAS2) were identified through Cytoscape.

Conclusion:

DEGs of psoriasis may play an essential role in disease development and may be potential pathogeneses of psoriasis.

References:

[1]Boehncke WH, Schon MP. Psoriasis. Lancet 2015;386(9997):983-94. doi: 10.1016/S0140-6736(14)61909-7 [published Online First: 2015/05/31].

[2]Zhang YJ, Sun YZ, Gao XH, et al. Integrated bioinformatic analysis of differentially expressed genes and signaling pathways in plaque psoriasis. Mol Med Rep 2019;20(1):225-35. doi: 10.3892/mmr.2019.10241 [published Online First: 2019/05/23].

[3]Zhou Y, Zhou B, Pache L, et al. Metascape provides a biologist-oriented resource for the analysis of systems-level datasets. Nat Commun 2019;10(1):1523. doi: 10.1038/s41467-019-09234-6 [published Online First: 2019/04/05].

Acknowledgements:

This project was supported by National Science Foundation of China (82001740), Open Fund from the Key Laboratory of Cellular Physiology (Shanxi Medical University) (KLCP2019) and Innovation Plan for Postgraduate Education in Shanxi Province (2020BY078).

Disclosure of Interests:

None declared

POS0742 SCREENING AND BIOINFORMATICS ANALYSIS OF HUB GENES AND PATHWAYS FOR PRIMARY SJÖGREN’S SYNDROME BASED ON GEO DATABASE

Background:

Primary Sjögren’s syndrome (pSS) is an autoimmune disease that featured as lymphoplasmacytic infiltration of the exocrine glands leading to sicca symptoms1. However, its underlying molecular mechanisms remain elusive.

Objectives:

This study aims to identify differentially expressed genes (DEGs) and pathways associated with the progression of pSS using bioinformatics analysis and explore its pathogenesis.

Methods:

The pSS-associated gene chip data set GSE66795 was obtained from the Gene Expression Omnibus (GEO) database, which included 131 cases of fully-phenotyped pSS patients’ whole blood samples and 29 cases of control samples. DEGs were screened Using R software. Online tool Metascape2 was used to make Gene Ontology (GO) and KEGG pathway enrichment. The PPI network was performed using String database. Hub genes were identified by Cytoscape.

Results:

A total of 108 DEGs were captured, including 101 up-regulated genes and 7 down-regulated genes. GO enrichment showed that these DEGs were primarily enriched in defense response to virus, response to interferon-gamma, regulation of innate immune response, response to interferon-beta, double-stranded RNA binding, response to interferon-alpha. KEGG pathway enrichment analysis showed these DEGs were principally enriched in Influenza A, RIG-I-like receptor signaling pathway, necroptosis, Staphylococcus aureus infection. Finally, 9 hub genes (STAT1, IRF7, OAS2, GBP1, OAS1, IFIT3, IFIH1, OAS3, DDX60) had highest degree value.

Conclusion:

The findings identified molecular mechanisms and the key hub genes that may involve in the occurrence and development of pSS.

References:

[1]Francois H, Mariette X. Renal involvement in primary Sjogren syndrome. Nat Rev Nephrol 2016;12(2):82-93. doi: 10.1038/nrneph.2015.174 [published Online First: 2015/11/17].

[2]Zhou Y, Zhou B, Pache L, et al. Metascape provides a biologist-oriented resource for the analysis of systems-level datasets. Nat Commun 2019;10(1):1523. doi: 10.1038/s41467-019-09234-6 [published Online First: 2019/04/05].

Acknowledgements:

This project was supported by National Science Foundation of China (82001740), Open Fund from the Key Laboratory of Cellular Physiology (Shanxi Medical University) (KLCP2019) and Innovation Plan for Postgraduate Education in Shanxi Province (2020BY078).

Disclosure of Interests:

None declared

POS0848 IDENTIFICATION OF POTENTIAL CRUCIAL GENES AND KEY PATHWAYS IN PULMONARY ARTERIAL HYPERTENSION WITH SYSTEMIC SCLEROSIS BY BIOINFORMATIC ANALYSIS

Background:

Pulmonary arterial hypertension with systemic sclerosis (SSc-PAH) is the main cause of death in patients with SSc. Early diagnosis and timely treatment are very important to reduce the mortality of patients with SSc-PAH1. At present, there are not many sensitive markers for the diagnosis of SSc-PAH. Therefore, it is necessary to mine more sensitive markers as more accurate and practical predictors, which is of great significance for the diagnosis and treatment of SSc-PAH.

Objectives:

To discover the differentially expressed genes (DEGs) and activated signaling pathways in SSc-PAH.

Methods:

Fifty-five samples (27 SSc-PAH v.s 28 normal controls) in GSE33463 chip data obtained from Gene Expression Omnibus (GEO) were included in this study. DEGs in SSc-PAH patients were screened by R, key pathways and hub genes were discoved by Metascape2, STRING3 and Cytoscape.

Results:

Total 431 genes with large differences were identified, including 238 up-regulated genes and 193 down-regulated genes, after standardizing the data (|logFC| > 1; P < 0.05). GO analysis showed that the upregulated genes were mainly involved in defense response to virus, hemoglobin complex, platelet alpha granule membrane and cytokine binding. The downregulated genes were mainly characterized by positive regulation of cell death, regulation of MAPK cascade, regulation of DNA-binding transcription factor activity and transcription factor AP-1 complex. Several significant enriched pathways obtained in the KEGG pathway analysis were Influenza A, Hepatitis C, IL-17 signaling pathway, MAPK signaling pathway, Toll-like receptor signaling pathway. Finally, after the selected differential genes were introduced into STRING online software, the data information of protein interaction network was derived, and 12 core genes in the network were identified, they were CXCL8, PPBP, LPAR1, FPR2, GNG11, CXCL10, LPAR5, JUN, C3AR1, CCR2, CCR3, IRF2.

Conclusion:

The genes and signal pathways related to SSc-PAH discovered by bioinformatics methods could not only provided new molecular markers for its diagnosis and treatment, but also provided new ideas for its related biological research.

References:

[1]Zheng JN, Li Y, Yan YM, et al. Identification and Validation of Key Genes Associated With Systemic Sclerosis-Related Pulmonary Hypertension. Front Genet 2020;11:816. doi: 10.3389/fgene.2020.00816 [published Online First: 2020/08/15].

[2]Zhou Y, Zhou B, Pache L, et al. Metascape provides a biologist-oriented resource for the analysis of systems-level datasets. Nat Commun 2019;10(1):1523. doi: 10.1038/s41467-019-09234-6 [published Online First: 2019/04/05].

[3]Szklarczyk D, Gable AL, Lyon D, et al. STRING v11: protein-protein association networks with increased coverage, supporting functional discovery in genome-wide experimental datasets. Nucleic Acids Res 2019;47(D1):D607-D13. doi: 10.1093/nar/gky1131 [published Online First: 2018/11/27].

Acknowledgements:

This project was supported by National Science Foundation of China (82001740), Open Fund from the Key Laboratory of Cellular Physiology (Shanxi Medical University) (KLCP2019) and Innovation Plan for Postgraduate Education in Shanxi Province (2020BY078).

Disclosure of Interests:

None declared

Pharmacokinetics of orbifloxacin in crucian carp (Carassius auratus) after intravenous and intramuscular administration

The pharmacokinetics of orbifloxacin was studied after a single dose (7.5 mg/kg) of intravenous or intramuscular administration to crucian carp (Carassius auratus) reared in freshwater at 25°C. Plasma samples were collected from six fish per sampling point. Orbifloxacin concentrations were determined by high-performance liquid chromatography with a 0.02 μg/ml limit of detection, then were subjected to noncompartmental analysis. After intravenous injection, initial concentration of 5.83 μg/ml, apparent elimination rate constant (λ_z ) of 0.039 hr^-1 , apparent elimination half-life (T_1/2λz ) of 17.90 hr, systemic total body clearance (Cl) of 75.47 ml hr^-1  kg^-1 , volume of distribution (Vz) of 1,948.76 ml/kg, and volume of distribution at steady-state (Vss) of 1,863.97 ml/kg were determined, respectively. While after intramuscular administration, the λ_z , T_1/2λz , mean absorption time (MAT), absorption half-life (T_1/2ka ), and bioavailability were determined as 0.027 hr^-1 , 25.69, 10.26, 7.11 hr, and 96.46%, respectively, while the peak concentration was observed as 3.11 ± 0.06 μg/ml at 2.0 hr. It was shown that orbifloxacin was completely but relatively slowly absorbed, extensively distributed, and slowly eliminated in crucian carp, and an orbifloxacin dosage of 10 mg/kg administered intravenously or intramuscularly would be expected to successfully treat crucian carp infected by strains with MIC values ≤0.5 μg/ml.

The roles of cytochrome P450 and P-glycoprotein in the pharmacokinetics of florfenicol in chickens

The effects of three selective oral inhibitors, fluvoxamine (FLU), ketoconazole (KET), and verapamil (VER), on the pharmacokinetics (PK) of florfenicol (FFC) were investigated in chickens. The chickens were administered orally with saline solution (SAL), FLU (60 mg/kg), KET (25 mg/kg), or VER (9 mg/kg) for 7 consecutive days. Florfenicol was given to the chickens at a single dose of 30 mg/kg orally. Blood samples were collected from each chicken at 0 to 12 h post-administration of FFC. The plasma concentration of FFC was analyzed by high-performance liquid chromatography (HPLC). The AUC of FFC increased and the CL_s of FFC decreased with oral co-administration of KET in chickens, and the C_max of FFC increased with VER. While the AUC, the CL_s and the C_max of FFC were all invariable with FLU. These data suggested that CYP 3A played a key role in the PK of FFC in chickens, however, P-glycoprotein (P-gp) and CYP 1A did not. The results imply that the adverse drug-drug interaction may occur in the use of FFC if the co-administrated drugs are the substrates, inducers or inhibitors of CYP 3A or/and P-gp.

Usefulness of mean platelet volume as a marker for clinical outcomes after out-of-hospital cardiac arrest: a retrospective cohort study

Essentials It is unknown whether mean platelet volume (MPV) estimates outcomes after cardiac arrest (CA). We investigated whether MPV was associated with 30-day neurologic outcome and mortality after CA. Elevated MPV at admission was associated with poor neurological outcomes and mortality at 30 days. Identifying levels of MPV is helpful for estimating disease severity among resuscitated patients.

SUMMARY

Background Whole-body ischemia followed by reperfusion during cardiac arrest and after return of spontaneous circulation (ROSC) triggers systemic sterile inflammatory responses, inducing a sepsis-like state during post-cardiac arrest syndrome. Activated platelets are enlarged, and contain vasoactive and prothrombic factors that aggravate systemic inflammation and endothelial dysfunction. Objectives To investigate whether mean platelet volume (MPV) is useful as a marker for early mortality and neurologic outcomes in patients who achieve ROSC after out-of-hospital cardiac arrest (OHCA). Methods OHCA records from the Emergency Department Cardiac Arrest Registry were retrospectively analyzed. Patients who survived for > 24 h after ROSC were included. We evaluated mortality and cerebral performance category scores after 30 days. Results We analyzed records from 184 patients with OHCA. Increased 30-day mortality among patients who achieved ROSC after OHCA was associated with MPV at admission (hazard ratio [HR] 1.36; 95% confidence interval [CI] 1.06-1.75). An elevated MPV at admission was also associated with poor neurologic outcomes (HR 1.28; 95% CI 1.06-1.55). Conclusions An elevated MPV was independently associated with increased 30-day mortality, with the highest discriminative value being obtained upon admission after OHCA. An elevated MPV on admission was associated with poor neurologic outcomes. High MPVs are helpful for estimating 30-day mortality and neurologic outcomes among patients who achieve ROSC after OHCA.

Gα12 is required for renal cystogenesis induced by Pkd1 inactivation

Mutation of PKD1, encoding the protein polycystin-1 (PC1), is the main cause of autosomal dominant polycystic kidney disease (ADPKD). The signaling pathways downstream of PC1 in ADPKD are still not fully understood. Here, we provide genetic evidence for the necessity of Gα12 (encoded by Gna12, hereafter Gα12) for renal cystogenesis induced by Pkd1 knockout. There was no phenotype in mice with deletion of Gα12 (Gα12^-/-). Polyinosine-polycytosine (pI:pC)-induced deletion of Pkd1 (Mx1Cre⁺Pkd1^f/fGα12^+/+) in 1-week-old mice resulted in multiple kidney cysts by 9 weeks, but the mice with double knockout of Pkd1 and Gα12 (Mx1Cre⁺Pkd1^f/fGα12^-/-) had no structural and functional abnormalities in the kidneys. These mice could survive more than one year without kidney abnormalities except multiple hepatic cysts in some mice, which indicates that the effect of Gα12 on cystogenesis is kidney specific. Furthermore, Pkd1 knockout promoted Gα12 activation, which subsequently decreased cell-matrix and cell-cell adhesion by affecting the function of focal adhesion and E-cadherin, respectively. Our results demonstrate that Gα12 is required for the development of kidney cysts induced by Pkd1 mutation in mouse ADPKD.

Linear magnetoresistance caused by mobility fluctuations in n-doped Cd(3)As(2)

Cd(3)As(2) is a candidate three-dimensional Dirac semimetal which has exceedingly high mobility and nonsaturating linear magnetoresistance that may be relevant for future practical applications. We report magnetotransport and tunnel diode oscillation measurements on Cd(3)As(2), in magnetic fields up to 65 T and temperatures between 1.5 and 300 K. We find that the nonsaturating linear magnetoresistance persists up to 65 T and it is likely caused by disorder effects, as it scales with the high mobility rather than directly linked to Fermi surface changes even when approaching the quantum limit. From the observed quantum oscillations, we determine the bulk three-dimensional Fermi surface having signatures of Dirac behavior with a nontrivial Berry phase shift, very light effective quasiparticle masses, and clear deviations from the band-structure predictions. In very high fields we also detect signatures of large Zeeman spin splitting (g∼16).

Polycystin-1 and Gα12 regulate the cleavage of E-cadherin in kidney epithelial cells

Interaction of polycystin-1 (PC1) and Gα12 is important for development of kidney cysts in autosomal dominant polycystic kidney disease (ADPKD). The integrity of cell polarity and cell-cell adhesions (mainly E-cadherin-mediated adherens junction) is altered in the renal epithelial cells of ADPKD. However, the key signaling pathway for this alteration is not fully understood. Madin-Darby canine kidney (MDCK) cells maintain the normal integrity of epithelial cell polarity and adherens junctions. Here, we found that deletion of Pkd1 increased activation of Gα12, which then promoted the cystogenesis of MDCK cells. The morphology of these cells was altered after the activation of Gα12. By using liquid chromatography-mass spectrometry, we found several proteins that could be related this change in the extracellular milieu. E-cadherin was one of the most abundant peptides after active Gα12 was induced. Gα12 activation or Pkd1 deletion increased the shedding of E-cadherin, which was mediated via increased ADAM10 activity. The increased shedding of E-cadherin was blocked by knockdown of ADAM10 or specific ADAM10 inhibitor GI254023X. Pkd1 deletion or Gα12 activation also changed the distribution of E-cadherin in kidney epithelial cells and caused β-catenin to shift from cell membrane to nucleus. Finally, ADAM10 inhibitor, GI254023X, blocked the cystogenesis induced by PC1 knockdown or Gα12 activation in renal epithelial cells. Our results demonstrate that the E-cadherin/β-catenin signaling pathway is regulated by PC1 and Gα12 via ADAM10. Specific inhibition of this pathway, especially ADAM10 activity, could be a novel therapeutic regimen for ADPKD.

Preparation of specific monoclonal antibodies against chelated copper ions

Copper ions are too small to elicit an immune response. Therefore, copper was conjugated to carrier proteins using S-2-(4-isothiocyanatobenzyl)-1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid, a bifunctional chelator, to make artificial antigens for copper. Several mice were immunized, and monoclonal antibodies (MAbs) against chelated copper were produced. Spleen cells of immunized mice were fused with myeloma cells. The resulting hybridomas were screened using protein conjugates which were covalently bound to metal-free 1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid (DOTA) or Cu-DOTA. Two hybridoma cell lines (F4 and B2) that produced MAbs with high selectivity and sensitivity were expanded for further study. Cross-reactivities with other metals were below 1%. These antibodies were used to construct competitive ELISAs for copper ions. The IC(50) for F4 and B2 were 0.39 and 1.66 mg/l, respectively. The detection range and the lowest detection limit for copper using the antibody F4 was 0.019-8.22 and 0.003 mg/l, respectively. Spike recovery studies in tap water showed that the most sensitive antibody could be used for copper detection in drinking water.

Curcumin improves insulin resistance in skeletal muscle of rats

BACKGROUND AND AIMS

Curcumin has been reported to lower plasma lipids and glucose in diabetic rats, and to decrease body weight in obese rats, which may partly be due to increased fatty acid oxidation and utilization in skeletal muscle.

METHODS AND RESULTS

Diabetic rats induced by high-fat diet plus streptozotocin (STZ, 30 mg/kg BW) were fed a diet containing 50, 150, or 250 mg/kg BW curcumin for 7 wk. Curcumin dose-dependently decreased plasma lipids and glucose and the dose 150 mg/kg BW appeared to be adequate to produce a significant effect. Curcumin supplementation reduced glucose and insulin tolerance measured as areas under the curve. L6 myotubes were treated with palmitate (0.25 mmol/L) in the presence of different levels of curcumin for 24 h in our in vitro experiment. Curcumin at 10 μmol/L was adequate to cause a significant increase in 2-deoxy-[(3)H]d-glucose uptake by L6 myotubes. Curcumin up-regulated expression of phosphorylated AMP-activated protein kinase (AMPK), CD36, and carnitine palmitoyl transferase 1, but down-regulated expression of pyruvate dehydrogenase 4 and phosphorylated glycogen synthase (GS) in both in vivo and in vitro studies. Moreover, curcumin increased phosphorylated acetyl COA carboxylase in L6 myotubes. The effects of curcumin on these enzymes except for GS were suppressed by AMPK inhibitor, Compound C. LKB1, an upstream kinase of AMPK, was activated by curcumin and inhibited by radicicol, an LKB1 destabilizer.

CONCLUSION

Curcumin improves muscular insulin resistance by increasing oxidation of fatty acid and glucose, which is, at least in part, mediated through LKB1-AMPK pathway.

Regulation of integrin expression by Gα12: An additional potential mechanism modulating cell attachment

Integrins regulate cell attachment and migration through interactions with specific proteins in the extra-cellular matrix. Heterotrimeric G proteins are essential signal transduction proteins that intersect with integrin signaling to regulate fundamental cellular behaviors. Although integrin and G protein signaling often act in concert, how these mechanisms interact in epithelial cells has not been extensively studied. We recently reported Gα12 regulation of epithelial cell attachment and migration on collagen-I through α2β1 integrins (Kong et al. Mol Biol Cell 2009). Activated Gα12 inhibited α2β1 integrin functions through an inside-out signaling mechanism that involved Rho, Src and protein phosphatases without affecting α2 or β1 expression. Activated Gα12 prevented tubulogenesis in 3D-MDCK cell cultures and promoted the formation of cystic structures. Herein, we extend these findings to show Gα12-stimulated transcriptional changes in integrin expression that affect MDCK cell attachment. Based on results from a microarray with MDCK cells expressing constitutively active Gα12 (QLα12), we confirmed with real time PCR that expressing QLα12 led to a 4-fold inhibition of α6 mRNA expression. Cell surface expression and total α6 protein was reduced by FACS and immunofluorescence. QLα12 expressing MDCK cells also revealed less attachment to laminin-5, an α6 integrin ligand. Taken together, G proteins regulate integrins through canonical signaling pathways and potentially regulate integrin expression levels to modulate cellular responses in a variety of pathophysiologic conditions including polycystic kidney disease.

Polycystin-1 protein level determines activity of the Galpha12/JNK apoptosis pathway

Mutations in PKD1 are the most common cause of autosomal dominant polycystic kidney disease (ADPKD). The protein product of PKD1 (polycystin-1 (PC1)) is a large transmembrane protein with a short intracellular C terminus that interacts with numerous signaling molecules, including Galpha(12). Cyst formation in ADPKD results from numerous cellular defects, including abnormal cilia, changes in polarity, and dysregulated apoptosis and proliferation. Recently, we reported increased apoptosis in Madin-Darby canine kidney (MDCK) cells through Galpha(12) stimulation of JNK and degradation of the anti-apoptotic protein Bcl-2 (Yanamadala, V., Negoro, H., Gunaratnam, L., Kong, T., and Denker, B. M. (2007) J. Biol. Chem. 282, 24352-24363). Herein, we confirm this pathway in Galpha(12)-silenced MDCK cells and utilize MDCK cell lines harboring either overexpressed or silenced PC1 to demonstrate that PC1 expression levels determine activity of the JNK/Bcl-2 apoptosis pathway. PC1-overexpressing MDCK cells were resistant to thrombin/Galpha(12)-stimulated apoptosis, JNK activation, and Bcl-2 degradation. In contrast, PC1-silenced MDCK cells displayed enhanced thrombin-induced apoptosis, JNK activity, and Bcl-2 degradation. In pulldown experiments, PC1 bound to Galpha(12), but not the related Galpha(13) subunit, and thrombin-stimulated MDCK cells led to increased interaction of Galpha(12) with the PC1 C terminus. In transient transfection assays, a PC1 C-terminal mutant lacking the G protein-binding domain was uncoupled from PC1-inhibited apoptosis. PC1 expression levels may be increased or decreased in ADPKD, and these findings suggest a mechanism in which levels of PC1 expression modulate Galpha(12)/JNK-stimulated apoptosis. Taken together, these findings are consistent with a set point model in which PC1 expression levels regulate specific G protein signaling pathways important to cyst development.

G alpha 12 inhibits alpha2 beta1 integrin-mediated Madin-Darby canine kidney cell attachment and migration on collagen-I and blocks tubulogenesis

Regulation of epithelial cell attachment and migration are essential for normal development and maintenance of numerous tissues. G proteins and integrins are critical signaling proteins regulating these processes, yet in polarized cells little is known about the interaction of these pathways. Herein, we demonstrate that G alpha 12 inhibits interaction of MDCK cells with collagen-I, the major ligand for alpha2 beta1 integrin. Activating G alpha 12 (QL point mutation or stimulating endogenous G alpha 12 with thrombin) inhibited focal adhesions and lamellipodia formation and led to impaired cell migration. Consistent with G alpha 12-regulated attachment to collagen-I, G alpha 12-silenced MDCK cells revealed a more adherent phenotype. Inhibiting Rho kinase completely restored normal attachment in G alpha 12-activated cells, and there was partial recovery with inhibition of Src and protein phosphatase pathways. G alpha 12 activation led to decreased phosphorylation of focal adhesion kinase and paxillin with displacement of alpha2 integrin from the focal adhesion protein complex. Using the MDCK cell 3D-tubulogenesis assay, activated G alpha 12 inhibited tubulogenesis and led to the formation of cyst-like structures. Furthermore, G alpha 12-silenced MDCK cells were resistant to thrombin-stimulated cyst development. Taken together, these studies provide direct evidence for G alpha 12-integrin regulation of epithelial cell spreading and migration necessary for normal tubulogenesis.

Identification of Pur alpha as a new hypoxia response factor responsible for coordinated induction of the beta 2 integrin family

Central to the process of inflammation are hypoxic conditions that lead to the binding of circulating leukocytes to the endothelium. We have previously shown that such binding is mediated by monocytes being able to directly sense hypoxic conditions and respond by inducing their surface expression of the beta(2) integrin family of adhesion molecules. In this study, we show that coordinated induction of the beta(2) integrins during direct hypoxia-sensing occurs through transcriptional activation of each of the genes by which they are encoded. Certain of the molecular mechanisms that mediate this activation in transcription are dependent upon hypoxia-inducible factor-1 (HIF-1), whereas others are HIF-1 independent. In search of these HIF-1-independent mechanisms, we identified Pur alpha as a new hypoxia-response factor. Binding of Pur alpha to the HIF-1-independent beta(2) integrin promoters is induced by hypoxia and mutagenesis of these Pur alpha-binding sites almost completely abolishes the ability of the promoters to respond to hypoxic conditions. Additional studies using siRNA directed against Pur alpha also revealed a loss in the hypoxic response of the beta(2) integrin promoters. Taken together, our findings demonstrate that hypoxia induces a coordinated up-regulation in beta(2) integrin expression that is dependent upon transcriptional mechanisms mediated by HIF-1 and Pur alpha.

Galpha12 stimulates apoptosis in epithelial cells through JNK1-mediated Bcl-2 degradation and up-regulation of IkappaBalpha

Apoptosis is an essential mechanism for the maintenance of somatic tissues, and when dysregulated can lead to numerous pathological conditions. G proteins regulate apoptosis in addition to other cellular functions, but the roles of specific G proteins in apoptosis signaling are not well characterized. Galpha12 stimulates protein phosphatase 2A (PP2A), a serine/threonine phosphatase that modulates essential signaling pathways, including apoptosis. Herein, we examined whether Galpha12 regulates apoptosis in epithelial cells. Inducible expression of Galpha12 or constitutively active (QL)alpha12 in Madin-Darby canine kidney cells led to increased apoptosis with expression of QLalpha12, but not Galpha12. Inducing QLalpha12 led to degradation of the anti-apoptotic protein Bcl-2 (via the proteasome pathway), increased JNK activity, and up-regulated IkappaBalpha protein levels, a potent stimulator of apoptosis. Furthermore, the QLalpha12-stimulated activation of JNK was blocked by inhibiting PP2A. To characterize endogenous Galpha12 signaling pathways, non-transfected MDCK-II and HEK293 cells were stimulated with thrombin. Thrombin activated endogenous Galpha12 (confirmed by GST-tetratricopeptide repeat (TPR) pull-downs) and stimulated apoptosis in both cell types. The mechanisms of thrombin-stimulated apoptosis through endogenous Galpha12 were nearly identical to the mechanisms identified in QLalpha12-MDCK cells and included loss of Bcl-2, JNK activation, and up-regulation of IkappaBalpha. Knockdown of the PP2A catalytic subunit in HEK293 cells inhibited thrombin-stimulated apoptosis, prevented JNK activation, and blocked Bcl-2 degradation. In summary, Galpha12 has a major role in regulating epithelial cell apoptosis through PP2A and JNK activation leading to loss of Bcl-2 protein expression. Targeting these pathways in vivo may lead to new therapeutic strategies for a variety of disease processes.

Identification of vasodilator-stimulated phosphoprotein (VASP) as an HIF-regulated tissue permeability factor during hypoxia

Increased tissue permeability is commonly associated with hypoxia of many origins. Since hypoxia-inducible factor (HIF) represents a predominant hypoxia signaling mechanism, we compared hypoxia-elicited changes in tissue barrier function in mice conditionally lacking intestinal epithelial hypoxia-inducible factor-1alpha (hif1a). Somewhat surprisingly, these studies revealed that mutant hif1a mice were protected from hypoxia-induced increases in intestinal permeability in vivo. Guided by microarray analysis of tissues derived from these mutant hif1a mice, we identified HIF-1-dependent repression of vasodilator-stimulated phosphoprotein (VASP), a molecule known to be important in the control of cytoskeletal dynamics, including barrier function. Studies at the mRNA and protein level confirmed hypoxia-elicited repression of VASP in murine tissue, cultured epithelia and endothelia, as well as human saphenous vein ex vivo. Targeted repression of VASP by siRNA recapitulated our findings with hypoxia and directed overexpression of VASP abolished hypoxia-induced barrier dysfunction. Studies in the cloned human VASP promoter revealed hypoxia-dependent transcriptional repression, and functional studies by chromatin immunoprecipitation (ChIP) and site-directed mutagenesis revealed hypoxia-dependent binding of HIF-1alpha to the human VASP promoter. These studies identify HIF-1-dependent repression of VASP as a control point for hypoxia-regulated barrier dysfunction.

HIF-dependent induction of adenosine A2B receptor in hypoxia

Adenosine has been widely associated with hypoxia of many origins, including those associated with inflammation and tumorogenesis. A number of recent studies have implicated metabolic control of adenosine generation at sites of tissue hypoxia. Here, we examine adenosine receptor control and amplification of signaling through transcriptional regulation of endothelial and epithelial adenosine receptors. Initial studies confirmed previous findings indicating selective induction of human adenosine A2B receptor (A2BR) by hypoxia. Analysis of the cloned human A2BR promoter identified a functional hypoxia-responsive region, including a functional binding site for hypoxia-inducible factor (HIF) within the A2BR promoter. Further studies examining HIF-1alpha DNA binding and HIF-1alpha gain and loss of function confirmed strong dependence of A2BR induction by HIF-1alpha in vitro and in vivo mouse models. Additional studies in endothelia overexpressing full-length A2BR revealed functional phenotypes of increased barrier function and enhanced angiogenesis. Taken together, these results demonstrate transcriptional coordination of A2BR by HIF-1alpha and amplified adenosine signaling during hypoxia. These findings may provide an important link between hypoxia and metabolic conditions associated with inflammation and angiogenesis.

Transcriptional repression of Na-K-2Cl cotransporter NKCC1 by hypoxia-inducible factor-1

Tissue edema is commonly associated with hypoxia. Generally, such episodes of fluid accumulation are self-limiting. At present, little is known about mechanisms to compensate excessive fluid transport. Here we describe an adaptive mechanism to dampen fluid loss during hypoxia. Initial studies confirmed previous observations of attenuated electrogenic Cl- secretion after epithelial hypoxia. A screen of known ion transporters in Cl- -secreting epithelia revealed selective downregulation of Na-K-2Cl cotransporter NKCC1 mRNA, protein, and function. Subsequent studies identified transcriptional repression of NKCC1 mediated by hypoxia-inducible factor (HIF). Chromatin immunoprecipitation analysis identified a functional HIF binding site oriented on the antisense strand of genomic DNA downstream of the transcription start site corresponding to the NKCC1 5'-untranslated region. Additional in vivo studies using conditional Hif1a-null mice revealed that the loss of HIF-1alpha in Cl- -secreting epithelia results in a loss of NKCC1 repression. These studies describe a novel regulatory pathway for NKCC1 transcriptional repression by hypoxia. These results suggest that HIF-dependent repression of epithelial NKCC1 may provide a compensatory mechanism to prevent excessive fluid loss during hypoxia.

HIF-dependent induction of apical CD55 coordinates epithelial clearance of neutrophils

Sites of inflammation are associated with dramatic shifts in tissue metabolism. Inflammation can result in significant tissue hypoxia, with resultant induction of hypoxia-responsive genes. Given this association, we hypothesized that neutrophil (PMN) ligands expressed on epithelial cells may be regulated by hypoxia. Initial studies confirmed earlier results that epithelial hypoxia enhances PMN transepithelial migration and promotes apical clearance of PMN from the epithelial surface. A screen of known PMN ligands revealed a surprisingly stable expression pattern in hypoxia. However, this screen identified one gene, CD55, as a highly hypoxia-inducible molecule expressed on the apical membrane of mucosal epithelia. Subsequent studies verified the induction of CD55 mRNA and protein expression by hypoxia. Overexpression of CD55 by transfection in nonhypoxic epithelia resulted in a similar pattern of apical PMN clearance, and peptide mimetics corresponding to the PMN binding site on DAF blocked such apical clearance of PMN. Studies directed at understanding molecular pathways of hypoxia inducibility revealed that a approximately 200 bp region of the CD55 gene conferred hypoxia inducibility for CD55. These studies identified a functional binding site for the transcriptional regulator hypoxia-inducible factor (HIF). Taken together, these results identify HIF-dependent induction of epithelial CD55 in the resolution of ongoing inflammation through clearance of apical PMN.

Induction of the von Hippel-Lindau tumor suppressor gene by late hypoxia limits HIF-1 expression

Hypoxia-inducible factor (HIF) remains the central focus of oxygen sensing during hypoxia. HIF is a heterodimeric transcription factor consisting of an oxygen-regulated alpha- and a constitutively expressed beta subunit. The von Hippel-Lindau tumor suppressor (pVHL) is a component of the E3 ubiquitin ligase complex and targets HIF-alpha to proteasomal degradation, but also is known to exert a significant control on HIF transactivation activity. However, the understanding of the full interaction between HIF and pVHL has been hindered by a lack in the understanding of pVHL regulation. Here, we report that pVHL itself is induced in prolonged hypoxia in a kinetic that parallels the observed downregulation of HIF-1alpha protein under such conditions. In addition, we document direct HIF-1alpha binding to the VHL promoter and identify a functional hypoxia response element (HRE) within the VHL promoter. Such induction of pVHL in hypoxia furthermore has functional implications for the HIF dependent hypoxic response, implicating a physiologically relevant feedback mechanism. These results provide an intriguing model, whereby HIF self-regulates expression through VHL and highlight the role of pVHL as a unifying mechanism of HIF regulation.

Leukocyte adhesion during hypoxia is mediated by HIF-1-dependent induction of beta2 integrin gene expression

Inflammatory responses are associated with significant changes in tissue metabolism. In particular, metabolic shifts during inflammation can result in significant tissue hypoxia, with resultant induction of hypoxia-responsive genes. Given this association, we hypothesized that leukocyte functional responses are influenced by hypoxia. Initial experiments revealed that exposure of the promonocytic cell line U937 to hypoxia resulted in increased adhesion to activated endothelia. Such increases were transcription-dependent and were blocked by antibodies directed against beta2, but not beta1, integrins. Analysis of beta2 integrin mRNA and protein in U937 cells revealed a 5- to 6-fold increase with hypoxia. Extension of this analysis to hypoxic human whole blood revealed prominent induction of beta2 integrin mRNA and protein ex vivo. Furthermore, murine beta2 integrin mRNA was found to be significantly induced during hypoxia in vivo. Subsequent studies identified a binding site for hypoxia-inducible factor 1 (HIF-1) in the CD18 gene. This gene encodes the subunit common to all four known types of beta2 integrin heterodimer. HIF-1 binding was demonstrated in vivo, and mutational analysis of the HIF-1 site within the CD18 promoter resulted in a loss of hypoxia inducibility. Taken together, these results demonstrate that hypoxia induces leukocyte beta2 integrin expression and function by transcriptional mechanisms dependent upon HIF-1.

Activation in vitro of somatostatin receptor subtypes 2, 3, or 4 stimulates protein tyrosine phosphatase activity in membranes from transfected Ras-transformed NIH 3T3 cells: coexpression with catalytically inactive SHP-2 blocks responsiveness

Somatostatin receptors (sstr) subtypes 1-5 were transiently expressed in NIH 3T3 cells stably transformed with Ha-Ras(G12V) to assess the ability of each receptor to stimulate protein tyrosine phosphatase (PTPase) activity in vitro. Treatment of membranes from sstr2-, sstr3-, or sstr4-expressing cells with somatostatin-14 plus guanyl-5'-yl imidodiphosphate (GMPPNP) increased PTPase activity, and this stimulation was pertussis toxin-sensitive. Somatostatin alone, GMPPNP alone, or somatostatin plus GDP were ineffective under these conditions. sstr1 and sstr5 failed to increase PTPase activity although both receptors were expressed, as assessed by appearance of high-affinity binding sites for [125I-Tyr11]somatostatin-14. Somatostatin plus GMPPNP stimulated PTPase activity in vitro when sstr2 was coexpressed with wild type PTP1B or a Cys to Ser (C/S), catalytically inactive PTP1B or with wild type SH2-domain containing PTPase SHP-2. However, coexpression with catalytically inactive C/S SHP-2 abrogated this response. Thus, three of the five cloned sstr's can couple to activate PTPase in this cellular background. Abrogation of the response by C/S SHP-2 strongly suggests, but does not prove, a role for SHP-2 in the mechanism.