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Marathe OS, Tang L, Tyler RC, Webb ML, Chen L, Wu C, Li W, Ju J, Luo J, Tang H, Vogelzang NJ. A survey study of prevention and treatment patterns by academic and community oncologists for cancer therapy-associated diarrhea. J Clin Oncol 2022. [DOI: 10.1200/jco.2022.40.4_suppl.076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
76 Background: Chemotherapy and targeted therapies are associated with GI toxicities including diarrhea that affects 50% to 80% of patients. Severe complications include dehydration, malnutrition, fatigue, renal insufficiency, and systemic infection. There are no specific prevention strategies, and treatment options are limited. Dose reduction or interruption of anti-cancer medications may lead to decreased efficacy. This survey was conducted to assess current toxicity management patterns and gaps for cancer therapy-associated diarrhea. Methods: An online survey (MedSurvey) with 6 eligibility & 15 practice questions was conducted (April 27 to 30, 2021). Fifty (50) practicing oncologists completed the survey. Results: Among the 50 oncologists,82% have been practicing ≥ 11 years with 24% from an academic setting and 76% from a community setting. They (percent of respondents) prescribed the following anti-cancer medications more than 10 times per week: cytotoxic chemotherapy (86%), targeted agents (78%), and immuno-oncology therapies (80%). Prevention of chemotherapy-induced diarrhea (CID) with Imodium (loperamide) and Lomotil (diphenoxylate and atropine) were commonly administered (10% always, 60% sometimes) as prophylactic treatment prior to the start of chemotherapy. The majority (60%) would prophylactically use a novel agent for a patient with previous CID, and 38% would use this agent for selected anti-cancer therapies. Many oncologists (5% always, 60% sometimes) start chemotherapy at a lower dose and titrate up to prevent CID. Similar treatment patterns were observed for targeted therapy induced diarrhea (TTID). For Grade 1 CID (multiple choices allowed), 18% used observation only for management, whereas 72% prescribed Imodium, and 22% used Lomotil. For Grade 1 TTID (multiple choices allowed), 26% used observation only, 58% prescribed Imodium, and 26% used Lomotil. Dose reduction was implemented 10% and 6% of the time for CID and TTID, respectively. For Grade 2 CID (multiple choices allowed) 4% used observation only, most started either Imodium (82%) or Lomotil (72%), and 34% considered dose reduction as a treatment strategy. For Imodium or Lomotil non-responders, 50% would dose reduce, and 44% would use an alternate anti-diarrheal treatment (e.g., octreotide). TTID had similar treatment patterns. For immune-oncology agents (e.g., ipilimumab, nivolumab, pembrolizumab) 40% suggested induced GI toxicities (e.g., diarrhea/colitis) require an innovation for managing toxicity. Conclusions: Treating cancer therapy-associated diarrhea continues to be a significant challenge with Grade 2/3 often requiring a therapeutic dose reduction or interruption that may impact the efficacy of cancer treatment. Effective management (prevention and treatment) for GI toxicity remains an unmet need for many patients.
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Affiliation(s)
| | - Lina Tang
- Affiliated Sixth People's Hospital, Shanghai Jiaotong University, Shanghai, China
| | | | | | | | | | - Wenxi Li
- OnQuality Pharmaceuticals, Seattle, WA
| | | | - Jie Luo
- OnQuality Pharmaceuticals, Seattle, WA
| | - Hong Tang
- OnQuality Pharmaceuticals, St. Louis, WA
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Dishman AF, Tyler RC, Fox JC, Kleist AB, Prehoda KE, Babu MM, Peterson FC, Volkman BF. Evolution of fold switching in a metamorphic protein. Science 2021; 371:86-90. [PMID: 33384377 PMCID: PMC8017559 DOI: 10.1126/science.abd8700] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Accepted: 11/11/2020] [Indexed: 12/14/2022]
Abstract
Metamorphic proteins switch between different folds, defying the protein folding paradigm. It is unclear how fold switching arises during evolution. With ancestral reconstruction and nuclear magnetic resonance, we studied the evolution of the metamorphic human protein XCL1, which has two distinct folds with different functions, making it an unusual member of the chemokine family, whose members generally adopt one conserved fold. XCL1 evolved from an ancestor with the chemokine fold. Evolution of a dimer interface, changes in structural constraints and molecular strain, and alteration of intramolecular protein contacts drove the evolution of metamorphosis. Then, XCL1 likely evolved to preferentially populate the noncanonical fold before reaching its modern-day near-equal population of folds. These discoveries illuminate how one sequence has evolved to encode multiple structures, revealing principles for protein design and engineering.
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Affiliation(s)
- Acacia F Dishman
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI, USA
- Medical Scientist Training Program, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Robert C Tyler
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Jamie C Fox
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Andrew B Kleist
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI, USA
- Medical Scientist Training Program, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Kenneth E Prehoda
- Institute of Molecular Biology, Department of Chemistry and Biochemistry, University of Oregon, Eugene, OR, USA
| | - M Madan Babu
- MRC Laboratory of Molecular Biology, Cambridge, UK
- Department of Structural Biology and Center for Data Driven Discovery, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Francis C Peterson
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI, USA
| | - Brian F Volkman
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI, USA.
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Higano CS, Armstrong AJ, Sartor O, Vogelzang NJ, Kantoff PW, McLeod DG, Pieczonka CM, Penson DF, Shore ND, Vacirca J, Concepcion RS, Tutrone RF, Nordquist LT, Quinn DI, Kassabian V, Scholz MC, Harmon M, Tyler RC, Chang NN, Tang H, Cooperberg MR. Reply to Potential underestimation of cerebrovascular events in the PROVENGE Registry for the Observation, Collection, and Evaluation of Experience Data. Cancer 2020; 126:2935-2937. [PMID: 32154908 DOI: 10.1002/cncr.32785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Celestia S Higano
- Division of Medical Oncology, Departments of Medicine and Urology, University of Washington, Seattle, Washington.,Fred Hutchinson Cancer Research Center, Seattle, Washington
| | - Andrew J Armstrong
- Divisions of Medical Oncology and Urology, Duke University Medical Center, Duke Cancer Institute, Duke University, Durham, North Carolina
| | - Oliver Sartor
- Section of Hematology and Medical Oncology, Department of Medicine, Tulane Cancer Center and Tulane University School of Medicine, New Orleans, Louisiana
| | - Nicholas J Vogelzang
- Division of Hematology/Oncology, Comprehensive Cancer Centers of Nevada, Las Vegas, Nevada
| | - Philip W Kantoff
- Department of Medicine, Memorial Sloan Kettering Cancer Center, Weill Cornell Medical College, New York, New York
| | - David G McLeod
- Department of Surgery, Center for Prostate Disease Research, Uniformed Services of Health Sciences, Walter Reed National Military Medical Center, Bethesda, Maryland
| | | | - David F Penson
- Departments of Urologic Surgery and Health Policy, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Neal D Shore
- Department of Urology, Carolina Urologic Research Center, Myrtle Beach, South Carolina
| | | | | | | | - Luke T Nordquist
- Department of Medical Oncology, GU Research Network, Omaha, Nebraska
| | - David I Quinn
- Division of Medical Oncology, Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, California
| | | | - Mark C Scholz
- Prostate Cancer Research Institute, Marina del Rey, California
| | - Matt Harmon
- Dendreon Pharmaceuticals LLC, Seattle, Washington
| | | | | | - Hong Tang
- Dendreon Pharmaceuticals LLC, Seattle, Washington
| | - Matthew R Cooperberg
- Departments of Urology and Epidemiology & Biostatistics, Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, San Francisco, California
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4
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Higano CS, Armstrong AJ, Sartor AO, Vogelzang NJ, Kantoff PW, McLeod DG, Pieczonka CM, Penson DF, Shore ND, Vacirca J, Concepcion RS, Tutrone RF, Nordquist LT, Quinn DI, Kassabian V, Scholz MC, Harmon M, Tyler RC, Chang NN, Tang H, Cooperberg MR. Real-world outcomes of sipuleucel-T treatment in PROCEED, a prospective registry of men with metastatic castration-resistant prostate cancer. Cancer 2019; 125:4172-4180. [PMID: 31483485 PMCID: PMC6856402 DOI: 10.1002/cncr.32445] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 07/12/2019] [Accepted: 07/17/2019] [Indexed: 01/14/2023]
Abstract
BACKGROUND The large registry, PROVENGE Registry for the Observation, Collection, and Evaluation of Experience Data (PROCEED)(NCT01306890), evaluated sipuleucel-T immunotherapy for asymptomatic/minimally symptomatic metastatic castration-resistant prostate cancer (mCRPC). METHODS PROCEED enrolled patients with mCRPC receiving 3 biweekly sipuleucel-T infusions. Assessments included overall survival (OS), serious adverse events (SAEs), cerebrovascular events (CVEs), and anticancer interventions (ACIs). Follow-up was for ≥3 years or until death or study withdrawal. RESULTS In 2011-2017, 1976 patients were followed for 46.6 months (median). The median age was 72 years, and the baseline median prostate-specific antigen level was 15.0 ng/mL; 86.7% were white, and 11.6% were African American. Among the patients, 1902 had 1 or more sipuleucel-T infusions. The median OS was 30.7 months (95% confidence interval [CI], 28.6-32.2 months). Known prognostic factors were independently associated with OS in a multivariable analysis. Among the 1255 patients who died, 964 (76.8%) died of prostate cancer (PC) progression. The median time from the first infusion to PC death was 42.7 months (95% CI, 39.4-46.2 months). The incidence of sipuleucel-T-related SAEs was 3.9%. The incidence of CVEs was 2.8%, and the rate per 100 person-years was 1.2 (95% CI, 0.9-1.6). The CVE incidence among 11,972 patients with mCRPC from the Surveillance, Epidemiology, and End Results-Medicare database was 2.8%; the rate per 100 person-years was 1.5 (95% CI, 1.4-1.7). One or more ACIs (abiraterone, enzalutamide, docetaxel, cabazitaxel, or radium 223) were received by 77.1% of the patients after sipuleucel-T; 32.5% and 17.4% of the patients experienced 1- and 2-year treatment-free intervals, respectively. CONCLUSIONS PROCEED provides contemporary survival data for sipuleucel-T-treated men in a real-world setting of new life-prolonging agents, which will be useful in discussing treatment options with patients and in powering future trials with sipuleucel-T. The safety and tolerability of sipuleucel-T in PROCEED were consistent with previous findings.
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Affiliation(s)
- Celestia S Higano
- Division of Medical Oncology, Departments of Medicine and Urology, University of Washington and Fred Hutchinson Cancer Research Center, Seattle, Washington
| | - Andrew J Armstrong
- Division of Medical Oncology, Duke University Medical Center, Duke Cancer Institute, Duke University, Durham, North Carolina.,Division of Urology, Duke University Medical Center, Duke Cancer Institute, Duke University, Durham, North Carolina
| | - A Oliver Sartor
- Section of Hematology and Medical Oncology, Department of Medicine, Tulane Cancer Center and Tulane University School of Medicine, New Orleans, Louisiana
| | - Nicholas J Vogelzang
- Division of Hematology/Oncology, Comprehensive Cancer Centers of Nevada, Las Vegas, Nevada
| | - Philip W Kantoff
- Department of Medicine, Memorial Sloan Kettering Cancer Center and Weill Cornell Medical College, New York, New York
| | - David G McLeod
- Department of Surgery, Center for Prostate Disease Research at the Uniformed Services of Health Sciences, Bethesda, Maryland
| | | | - David F Penson
- Department of Urologic Surgery, Vanderbilt University Medical Center, Nashville, Tennessee.,Department of Health Policy, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Neal D Shore
- Department of Urology, Carolina Urologic Research Center, Myrtle Beach, South Carolina
| | | | | | | | - Luke T Nordquist
- Department of Medical Oncology, GU Research Network, Omaha, Nebraska
| | - David I Quinn
- Division of Medical Oncology, Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, California
| | | | - Mark C Scholz
- Prostate Cancer Research Institute, Marina del Rey, California
| | - Matt Harmon
- Department of Biometrics, Dendreon Pharmaceuticals LLC, Seattle, Washington
| | - Robert C Tyler
- Department of Medical Affairs, Dendreon Pharmaceuticals LLC, Seattle, Washington
| | - Nancy N Chang
- Department of Medical Affairs, Dendreon Pharmaceuticals LLC, Seattle, Washington
| | - Hong Tang
- Department of Medical Affairs, Dendreon Pharmaceuticals LLC, Seattle, Washington
| | - Matthew R Cooperberg
- Department of Urology, Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, San Francisco, California.,Department of Epidemiology and Biostatistics, Helen Diller Family Comprehensive Cancer Center, University of California San Francisco, San Francisco, California
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5
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Kleist AB, Peterson F, Tyler RC, Gustavsson M, Handel TM, Volkman BF. Solution NMR spectroscopy of GPCRs: Residue-specific labeling strategies with a focus on 13C-methyl methionine labeling of the atypical chemokine receptor ACKR3. Methods Cell Biol 2018; 149:259-288. [PMID: 30616824 DOI: 10.1016/bs.mcb.2018.09.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The past decade has witnessed remarkable progress in the determination of G protein-coupled receptor (GPCR) structures, profoundly expanding our understanding of how GPCRs recognize ligands, become activated, and interact with intracellular signaling components. In recent years, numerous studies have used solution nuclear magnetic resonance (NMR) spectroscopy to investigate GPCRs, providing fundamental insights into GPCR conformational changes, allostery, dynamics, and other facets of GPCR function are challenging to study using other structural techniques. Despite these advantages, NMR-based studies of GPCRs are few relative to the number of published structures, due in part to the challenges and limitations of NMR for the characterization of large membrane proteins. Several studies have circumvented these challenges using a variety of isotopic labeling strategies, including side chain derivatization and metabolic incorporation of NMR-active nuclei. In this chapter, we provide an overview of different isotopic labeling strategies and describe an in-depth protocol for the expression, purification, and NMR studies of the chemokine GPCR atypical chemokine receptor 3 (ACKR3) via 13CH3-methionine incorporation. The goal of this chapter is to provide a resource to the GPCR community for those interested in pursuing NMR studies of GPCRs.
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Affiliation(s)
- Andrew B Kleist
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Francis Peterson
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Robert C Tyler
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI, United States
| | - Martin Gustavsson
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, CA, United States
| | - Tracy M Handel
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, CA, United States
| | - Brian F Volkman
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI, United States.
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6
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Higano CS, Armstrong AJ, Sartor AO, Vogelzang NJ, Kantoff PW, McLeod DG, Pieczonka CM, Penson DF, Shore ND, Vacirca JL, Concepcion RS, Tutrone RF, Nordquist LT, Quinn DI, Kassabian V, Scholz MC, Tyler RC, Chang NN, Brown B, Cooperberg MR. Cerebrovascular event (CVE) outcome and overall survival (OS) in patients (pts) treated with sipuleucel-T (sip-T) for metastatic castration-resistant prostate cancer (mCRPC): results from the PROCEED registry. J Clin Oncol 2018. [DOI: 10.1200/jco.2018.36.15_suppl.e17018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Celestia S. Higano
- University of Washington and Fred Hutchinson Cancer Research Center, Seattle, WA
| | | | | | | | | | - David G. McLeod
- Center for Prostate Disease Research, Uniformed Services University of Health Sciences, Bethesda, MD
| | | | | | | | | | | | | | | | - David I. Quinn
- University of Southern California Norris Comprehensive Cancer Center, Los Angeles, CA
| | | | | | | | | | - Bruce Brown
- Dendreon Pharmaceuticals LLC, Seattle, WA, US
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7
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Petrylak DP, Drake CG, Pieczonka CM, Corman JM, Garcia JA, Dunshee C, Van Mouwerik T, Tyler RC, Chang NN, Quinn D. Overall survival and immune responses with sipuleucel-T and enzalutamide: STRIDE study. J Clin Oncol 2018. [DOI: 10.1200/jco.2018.36.6_suppl.246] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
246 Background: STRIDE (NCT01981122) is the first study comparing concurrent (con) vs sequential (seq) enzalutamide (enz) with sipuleucel-T (sip-T) in patients (pts) with metastatic castration-resistant prostate cancer. Pts were followed until death or for 3 years. Methods: Fifty-two pts were randomized 1:1 to 3 sip-T infusions and enz started 2 wks before (n = 25, con) or 10 wks after (n = 27, seq) sip-T. Enz was continued for 52 wks or until disease progression (DP)/toxicity. Time to clinical outcomes was estimated by Kaplan-Meier analysis. Results: Median age (years): con 66; seq 72 (p = 0.01). Baseline characteristics and laboratory values were similar between arms. K-M estimated median follow up: 40.2 months. Clinical trial information: NCT01981122. Conclusions: Long-term follow-up suggests sip-T+enz is well-tolerated with no new safety concerns. Though not powered for such, con vs seq rx did not result in differences in OS or DP; differences in PSA responses cannot be excluded. Larger studies could better evaluate the clinical impact of combining immunotherapy with hormonal agents.[Table: see text]
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Affiliation(s)
| | - Charles G. Drake
- Columbia University Herbert Irving Comprehensive Cancer Center, New York, NY
| | | | | | | | - Curtis Dunshee
- Urological Associates of Southern Arizona P.C., Tucson, AZ
| | | | | | | | - David Quinn
- USC Keck School of Medicine Norris Comprehensive Cancer Center, Los Angeles, CA
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8
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Freedland SJ, Smith MR, Concepcion RS, Pieczonka CM, Gartrell BA, Schiffman Z, Van Mouwerik T, Tyler RC, Chang NN, Shore ND. Predict: Evaluation of baseline characteristics predictive of distant metastases in patients with castration-resistant prostate cancer—Updated data. J Clin Oncol 2018. [DOI: 10.1200/jco.2018.36.6_suppl.253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
253 Background: Metrics predicting a positive imaging test for men presumed M0 castration-resistant prostate cancer (CRPC) are not universally accepted/implemented. PREDICT (NCT01981109) evaluates characteristics predictive of a baseline (BL) imaging study positive for distant mets (M1) in men with presumed M0 CRPC, and follows those with confirmed M0 disease to M1 development. Methods: Men with no imaging in the previous 3 months (mos) were enrolled in the registry. Imaging modality to detect mets was at investigator’s discretion. Based on BL imaging, patients were classified as M0 or M1. Results: PREDICT enrolled 224 men, of whom 208 had BL scan/image data; 55 (25%) men presented with undetected M1. Visceral disease was noted in 11% of men presenting with M1 disease; 60% had bone only disease, 18% had nodal only disease and 11% had bone + nodal disease. Bone mets were found in 16% (25/160) of Tc99 scans vs 40% (19/48) of NaF PET (p = 0.0004). Of men with M0 at BL, 37/153 (24%) became M1 at a mean time from study entry of 11.9 mos. Mean follow-up was 28 mos. In these men, the only notable change in laboratory values from BL was PSA (mean: 16 vs 69 ng/mL; p = 0.020) and PSADT (7.7 vs 6.3 mos; p < 0.001). Baseline PSADT was 10.9 (M0) and 5.7 (M1) mos. BL mean laboratory values were significantly higher (p < 0.01) in the M1 vs M0 group for PSA (47 vs 10 ng/mL), alkaline phosphatase (111 vs 77 U/L), and prostatic acid phosphatase (8.2 vs 2.5 ng/mL). Conclusions: A high proportion (25%) of men presented with asymptomatic, occult mets, and 11% of the occult mets involved visceral disease. In men with documented M0 CRPC, approximately a quarter will develop mets in the next 12 mos. Early detection of occult mets will allow patients to initiate therapies shown to improve overall survival. Clinical trial information: NCT01981109.
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9
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Reis LM, Tyler RC, Weh E, Hendee KE, Schilter KF, Phillips JA, Sequeira S, Schinzel A, Semina EV. Whole exome sequencing identifies multiple diagnoses in congenital glaucoma with systemic anomalies. Clin Genet 2016; 90:378-82. [PMID: 27272408 DOI: 10.1111/cge.12816] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Revised: 05/23/2016] [Accepted: 06/02/2016] [Indexed: 11/28/2022]
Abstract
The genetic basis of congenital glaucoma with systemic anomalies is largely unknown. Whole exome sequencing (WES) in 10 probands with congenital glaucoma and variable systemic anomalies identified pathogenic or likely pathogenic variants in three probands; in two of these, a combination of two Mendelian disorders was found to completely explain the patients' features whereas in the third case only the ocular findings could be explained by the genetic diagnosis. The molecular diagnosis for glaucoma included two cases with compound heterozygous or homozygous pathogenic alleles in CYP1B1 and one family with a dominant pathogenic variant in FOXC1; the second genetic diagnosis for the additional systemic features included compound heterozygous mutations in NPHS1 in one family and a heterozygous 18q23 deletion in another pedigree. These findings show the power of WES in the analysis of complex conditions and emphasize the importance of CYP1B1 screening in patients with congenital glaucoma regardless of the presence/absence of other systemic anomalies.
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Affiliation(s)
- L M Reis
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin and Children's Hospital of Wisconsin, Milwaukee, WI, USA
| | - R C Tyler
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin and Children's Hospital of Wisconsin, Milwaukee, WI, USA
| | - E Weh
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin and Children's Hospital of Wisconsin, Milwaukee, WI, USA.,Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA
| | - K E Hendee
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin and Children's Hospital of Wisconsin, Milwaukee, WI, USA.,Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA
| | - K F Schilter
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin and Children's Hospital of Wisconsin, Milwaukee, WI, USA.,Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA
| | - J A Phillips
- Division of Medical Genetics and Genomic Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - S Sequeira
- Metabolic Unit, Pediatric Department, Hospital de Dona Estefânia, CHLC, Lisbon, Portugal
| | - A Schinzel
- Department of Genetics, Institute of Medical Genetics, Schwerzenbach, Switzerland
| | - E V Semina
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin and Children's Hospital of Wisconsin, Milwaukee, WI, USA. .,Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA. .,Department of Ophthalmology, Medical College of Wisconsin, Milwaukee, WI, USA.
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10
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Nevins AM, Subramanian A, Tapia JL, Delgado DP, Tyler RC, Jensen DR, Ouellette AJ, Volkman BF. A Requirement for Metamorphic Interconversion in the Antimicrobial Activity of Chemokine XCL1. Biochemistry 2016; 55:3784-93. [PMID: 27305837 DOI: 10.1021/acs.biochem.6b00353] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Chemokines make up a superfamily of ∼50 small secreted proteins (8-12 kDa) involved in a host of physiological processes and disease states, with several previously shown to have direct antimicrobial activity comparable to that of defensins in efficacy. XCL1 is a unique metamorphic protein that interconverts between the canonical chemokine fold and a novel all-β-sheet dimer. Phylogenetic analysis suggests that, within the chemokine family, XCL1 is most closely related to CCL20, which exhibits antibacterial activity. The in vitro antimicrobial activity of WT-XCL1 and structural variants was quantified using a radial diffusion assay (RDA) and in solution bactericidal assays against Gram-positive and Gram-negative species of bacteria. Comparisons of WT-XCL1 with variants that limit metamorphic interconversion showed a loss of antimicrobial activity when restricted to the conserved chemokine fold. These results suggest that metamorphic folding of XCL1 is required for potent antimicrobial activity.
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Affiliation(s)
- Amanda M Nevins
- Department of Biochemistry, Medical College of Wisconsin , Milwaukee, Wisconsin 53226, United States
| | - Akshay Subramanian
- Department of Pathology and Laboratory Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California , Los Angeles, California 90089, United States
| | - Jazma L Tapia
- Department of Pathology and Laboratory Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California , Los Angeles, California 90089, United States
| | - David P Delgado
- Department of Pathology and Laboratory Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California , Los Angeles, California 90089, United States
| | - Robert C Tyler
- Department of Biochemistry, Medical College of Wisconsin , Milwaukee, Wisconsin 53226, United States
| | - Davin R Jensen
- Department of Biochemistry, Medical College of Wisconsin , Milwaukee, Wisconsin 53226, United States
| | - André J Ouellette
- Department of Pathology and Laboratory Medicine, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California , Los Angeles, California 90089, United States
| | - Brian F Volkman
- Department of Biochemistry, Medical College of Wisconsin , Milwaukee, Wisconsin 53226, United States
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11
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Fox JC, Tyler RC, Peterson FC, Dyer DP, Zhang F, Linhardt RJ, Handel TM, Volkman BF. Examination of Glycosaminoglycan Binding Sites on the XCL1 Dimer. Biochemistry 2016; 55:1214-25. [PMID: 26836755 DOI: 10.1021/acs.biochem.5b01329] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Known for its distinct metamorphic behavior, XCL1 interconverts between a canonical chemokine folded monomer (XCL1mon) that interacts with the receptor, XCR1, and a unique dimer (XCL1dim) that interacts with glycosaminoglycans and inhibits HIV-1 activity. This study presents the first detailed analysis of the GAG binding properties of XCL1dim. Basic residues within a conformationally selective dimeric variant of XCL1 (W55D) were mutated and analyzed for their effects on heparin binding. Mutation of Arg23 and Arg43 greatly diminished the level of heparin binding in both heparin Sepharose chromatography and surface plasmon resonance assays. To assess the contributions of different GAG structures to XCL1 binding, we developed a solution fluorescence polarization assay and correlated affinity with the length and level of sulfation of heparan sulfate oligosaccharides. It was recently demonstrated that the XCL1 GAG binding form, XCL1dim, is responsible for preventing HIV-1 infection through interactions with gp120. This study defines a GAG binding surface on XCL1dim that includes residues that are important for HIV-1 inhibition.
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Affiliation(s)
- Jamie C Fox
- Department of Biochemistry, Medical College of Wisconsin , Milwaukee, Wisconsin 53226, United States
| | - Robert C Tyler
- Department of Biochemistry, Medical College of Wisconsin , Milwaukee, Wisconsin 53226, United States
| | - Francis C Peterson
- Department of Biochemistry, Medical College of Wisconsin , Milwaukee, Wisconsin 53226, United States
| | - Douglas P Dyer
- Skaggs School of Pharmacy and Pharmaceutical Sciences, Department of Pharmacology, University of California at San Diego , La Jolla, California 92093, United States
| | - Fuming Zhang
- Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
| | - Robert J Linhardt
- Department of Chemistry and Chemical Biology, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
| | - Tracy M Handel
- Skaggs School of Pharmacy and Pharmaceutical Sciences, Department of Pharmacology, University of California at San Diego , La Jolla, California 92093, United States
| | - Brian F Volkman
- Department of Biochemistry, Medical College of Wisconsin , Milwaukee, Wisconsin 53226, United States
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12
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Fox JC, Tyler RC, Guzzo C, Tuinstra RL, Peterson FC, Lusso P, Volkman BF. Engineering Metamorphic Chemokine Lymphotactin/XCL1 into the GAG-Binding, HIV-Inhibitory Dimer Conformation. ACS Chem Biol 2015; 10:2580-8. [PMID: 26302421 DOI: 10.1021/acschembio.5b00542] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Unlike other chemokines, XCL1 undergoes a distinct metamorphic interconversion between a canonical monomeric chemokine fold and a unique β-sandwich dimer. The monomeric conformation binds and activates the receptor XCR1, whereas the dimer binds extracellular matrix glycosaminoglycans and has been associated with anti-human immunodeficiency virus (HIV) activity. Functional studies of WT-XCL1 are complex, as both conformations are populated in solution. To overcome this limitation, we engineered a stabilized dimeric variant of XCL1 designated CC5. This variant features a new disulfide bond (A36C-A49C) that prevents structural interconversion by locking the chemokine into the β-sandwich dimeric conformation, as demonstrated by NMR structural analysis and hydrogen/deuterium exchange experiments. Functional studies analyzing glycosaminoglycan binding demonstrate that CC5 binds with high affinity to heparin. In addition, CC5 exhibits potent inhibition of HIV-1 activity in primary peripheral blood mononuclear cells (PBMCs), demonstrating the importance of the dimer in blocking viral infection. Conformational variants like CC5 are valuable tools for elucidating the biological relevance of the XCL1 native-state interconversion and will assist in future antiviral and functional studies.
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Affiliation(s)
- Jamie C. Fox
- Department
of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, United States
| | - Robert C. Tyler
- Department
of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, United States
| | - Christina Guzzo
- Laboratory
of Immunoregulation, National Institute of Allergy and Infectious
Diseases, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Robbyn L. Tuinstra
- Department
of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, United States
| | - Francis C. Peterson
- Department
of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, United States
| | - Paolo Lusso
- Laboratory
of Immunoregulation, National Institute of Allergy and Infectious
Diseases, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Brian F. Volkman
- Department
of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, United States
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13
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Harvey SR, Porrini M, Tyler RC, MacPhee CE, Volkman BF, Barran PE. Electron capture dissociation and drift tube ion mobility-mass spectrometry coupled with site directed mutations provide insights into the conformational diversity of a metamorphic protein. Phys Chem Chem Phys 2015; 17:10538-50. [DOI: 10.1039/c4cp05136j] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Ion mobility mass spectrometry can be combined with data from top-down sequencing to discern adopted conformations of proteins in the absence of solvent.
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Affiliation(s)
| | - Massimiliano Porrini
- Institut Européen de Chimie et Biologie (IECB)
- U869 ARNA – Inserm Chimie et Biologie des Membranes et des Nano-objets (CBMN)
- 33607 Pessac Cedex
- France
| | - Robert C. Tyler
- Department of Biochemistry
- Medical College of Wisconsin
- Milwaukee
- USA
| | - Cait E. MacPhee
- School of Physics and Astronomy
- University of Edinburgh
- Edinburgh
- UK
| | - Brian F. Volkman
- Department of Biochemistry
- Medical College of Wisconsin
- Milwaukee
- USA
| | - Perdita E. Barran
- School of Chemistry
- Manchester Institute of Biotechnology
- University of Manchester
- Manchester
- UK
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14
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Fox JC, Nakayama T, Tyler RC, Sander TL, Yoshie O, Volkman BF. Structural and agonist properties of XCL2, the other member of the C-chemokine subfamily. Cytokine 2014; 71:302-11. [PMID: 25497737 DOI: 10.1016/j.cyto.2014.11.010] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 11/04/2014] [Accepted: 11/10/2014] [Indexed: 10/24/2022]
Abstract
Known for its unusual metamorphic native state structure, XCL1 has been the focus of most efforts to elucidate the structural, functional, and physiological properties of chemokines in the C subfamily. By comparison, its closely related paralog XCL2 remains virtually uncharacterized. Based on the importance of the chemokine N-terminus in receptor activation, it was hypothesized that two amino acid differences in XCL2 would alter its agonist activity relative to XCL1 for their shared receptor XCR1. This present study reveals several properties of XCL2 that were unexamined until now. Structurally, XCL1 and XCL2 are very similar, exchanging between the monomeric chemokine fold and an unrelated dimeric state under physiological NaCl and temperature conditions. Ca(2+) flux, chemotaxis, and heparin binding assays showed that the monomer form of XCL2 is responsible for G protein-coupled receptor activation while the dimeric form is important for GAG binding. Despite their high structural similarity, XCL2 displays a slightly higher affinity for heparin than XCL1. Because their in vitro functional profiles are virtually identical, distinct physiological roles for XCL1 and XCL2 are probably encoded at the level of expression.
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Affiliation(s)
- Jamie C Fox
- Department of Biochemistry, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - Takashi Nakayama
- Division of Chemotherapy, Kinki University, Faculty of Pharmacy, Higashi-osaka 577-8502, Japan
| | - Robert C Tyler
- Department of Biochemistry, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA
| | - Tara L Sander
- Department of Pediatric Pathology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Osamu Yoshie
- Kinki University, Faculty of Medicine, Osaka-Sayama, Osaka 589-851, Japan
| | - Brian F Volkman
- Department of Biochemistry, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
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15
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Harvey SR, Porrini M, Konijnenberg A, Clarke DJ, Tyler RC, Langridge-Smith PRR, MacPhee CE, Volkman BF, Barran PE. Dissecting the Dynamic Conformations of the Metamorphic Protein Lymphotactin. J Phys Chem B 2014; 118:12348-59. [DOI: 10.1021/jp504997k] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
| | - Massimiliano Porrini
- Institut Européen de Chimie et Biologie (IECB), CNRS UMR 5248 Chimie et Biologie des Membranes et des Nano-objets (CBMN), 33607 Pessac Cedex, France
| | | | | | - Robert C. Tyler
- Department
of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, United States
| | | | | | - Brian F. Volkman
- Department
of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, United States
| | - Perdita E. Barran
- School
of Chemistry,
Manchester Institute of Biotechnology, University of Manchester, Manchester M1 7DN, United Kingdom
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16
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Weh E, Reis LM, Tyler RC, Bick D, Rhead WJ, Wallace S, McGregor TL, Dills SK, Chao MC, Murray JC, Semina EV. Novel B3GALTL mutations in classic Peters plus syndrome and lack of mutations in a large cohort of patients with similar phenotypes. Clin Genet 2013; 86:142-8. [PMID: 23889335 DOI: 10.1111/cge.12241] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Revised: 07/17/2013] [Accepted: 07/17/2013] [Indexed: 11/30/2022]
Abstract
Peters plus syndrome (PPS) is a rare autosomal-recessive disorder characterized by Peters anomaly of the eye, short stature, brachydactyly, dysmorphic facial features, developmental delay, and variable other systemic abnormalities. In this report, we describe screening of 64 patients affected with PPS, isolated Peters anomaly and PPS-like phenotypes. Mutations in the coding region of B3GALTL were identified in nine patients; six had a documented phenotype of classic PPS and the remaining three had a clinical diagnosis of PPS with incomplete clinical documentation. A total of nine different pathogenic alleles were identified. Five alleles are novel including one frameshift, c.168dupA, p.(Gly57Argfs*11), one nonsense, c.1234C>T, p.(Arg412*), two missense, c.1045G>A, p.(Asp349Asn) and c.1181G>A, p.(Gly394Glu), and one splicing, c.347+5G>T, mutations. Consistent with previous reports, the c.660+1G>A mutation was the most common mutation identified, seen in eight of the nine patients and accounting for 55% of pathogenic alleles in this study and 69% of all reported pathogenic alleles; while two patients were homozygous for this mutation, the majority had a second rare pathogenic allele. We also report the absence of B3GALTL mutations in 55 cases of PPS-like phenotypes or isolated Peters anomaly, further establishing the strong association of B3GALTL mutations with classic PPS only.
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Affiliation(s)
- E Weh
- Department of Pediatrics, Children's Research Institute, Medical College of Wisconsin, Children's Hospital of Wisconsin, Milwaukee, WI, USA; Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, WI, USA
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17
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Tyler RC, Wieting JC, Peterson FC, Volkman BF. Electrostatic optimization of the conformational energy landscape in a metamorphic protein. Biochemistry 2012; 51:9067-75. [PMID: 23102260 DOI: 10.1021/bi300842j] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The equilibrium unfolding reaction of Ltn, a metamorphic C-class chemokine, was monitored by tryptophan fluorescence to determine unfolding free energies. Measurements revealed that addition of 150 mM NaCl stabilized the Ltn chemokine fold by approximately 1 kcal/mol. Specific mutations involving Arg23 and Arg43 also increased the stability by 1 kcal/mol, suggesting their involvement in chloride ion coordination. This interaction was confirmed by nuclear magnetic resonance (NMR) salt titration studies that revealed chemical shift perturbations localized to these residues and backbone amides within the proximal 40s loop. The effects of NaCl on the free energy landscape were further verified by ZZ-exchange NMR spectroscopy. Our results suggest that changes in the electrostatic environment modulate the Gibbs free energy of folding and alter the forward and reverse rates of interconversion. These results demonstrate how solution ions can promote metamorphic folding by adjusting the relative stabilities of two unrelated Ltn native-state structures.
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Affiliation(s)
- Robert C Tyler
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, United States
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18
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Abstract
Lymphotactin (Ltn) is a unique chemokine that under physiological solution conditions displays large-scale structural heterogeneity, defining a new category of "metamorphic proteins". Previous Ltn studies have indicated that each form is required for proper function, but the mechanism of interconversion remains unknown. Here we have investigated the temperature dependence of kinetic rates associated with interconversion and unfolding by stopped-flow fluorescence to determine transition-state free energies. Comparisons of derived thermodynamic parameters revealed striking similarities between interconversion and protein unfolding. We conclude that Ltn native-state rearrangement proceeds by way of a large-scale unfolding process rather than a unique intermediate structure.
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Affiliation(s)
- Robert C Tyler
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
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19
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Schilter KF, Schneider A, Bardakjian T, Soucy JF, Tyler RC, Reis LM, Semina EV. OTX2 microphthalmia syndrome: four novel mutations and delineation of a phenotype. Clin Genet 2011; 79:158-68. [PMID: 20486942 DOI: 10.1111/j.1399-0004.2010.01450.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The OTX2 homeobox-containing transcription factor gene was shown to play a key role in the development of head structures in vertebrates. In humans, OTX2 mutations result in anophthalmia/microphthalmia (A/M) often associated with systemic anomalies. We screened 52 unrelated individuals affected with A/M and identified disease-causing variants in four families (8%), a higher frequency than previously reported. All four mutations are predicted to result in truncation of normal OTX2 protein sequence, consistent with previously reported mechanisms; three changes occurred de novo and one mutation was inherited from an affected parent. Four of the five OTX2-positive patients in our study displayed additional systemic findings, including two novel features, Wolf-Parkinson-White syndrome and an anteriorly placed anus. Analysis of the phenotypic features of OTX2-positive A/M patients in this study and those previously reported suggests the presence of pituitary anomalies and lack of genitourinary and gastrointestinal manifestations as potential distinguishing characteristics from SOX2 anophthalmia syndrome. Interestingly, pituitary anomalies seem to be more strongly associated with mutations that occur in the second half of OTX2, after the homeodomain and SGQFTP motif. OTX2 patients also show a high rate of inherited mutations (35%), often from mildly or unaffected parents, emphasizing the importance of careful parental examination/testing.
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Affiliation(s)
- K F Schilter
- Department of Pediatrics and Children's Research Institute, Medical College of Wisconsin and Children's Hospital of Wisconsin, Milwaukee, WI 53226-0509, USA
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20
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Sun Q, Tyler RC, Volkman BF, Julian RR. Dynamic interchanging native states of lymphotactin examined by SNAPP-MS. J Am Soc Mass Spectrom 2011; 22:399-407. [PMID: 21472559 PMCID: PMC3061006 DOI: 10.1007/s13361-010-0042-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2010] [Revised: 11/15/2010] [Accepted: 11/15/2010] [Indexed: 05/30/2023]
Abstract
The human chemokine lymphotactin (Ltn) is a remarkable protein that interconverts between two unrelated native state structures in the condensed phase. It is possible to shift the equilibrium toward either conformation with selected sequence substitutions. Previous results have shown that a disulfide-stabilized variant preferentially adopts the canonical chemokine fold (Ltn10), while a single amino acid change (W55D) favors the novel Ltn40 dimeric structure. Selective noncovalent adduct protein probing (SNAPP) is a recently developed method for examining solution phase protein structure. Herein, it is demonstrated that SNAPP can easily recognize and distinguish between the Ltn10 and Ltn40 states of lymphotactin in aqueous solution. The effects of organic denaturants, acid, and disulfide bond reduction and blocking were also examined using SNAPP for the CC3, W55D, and wild type proteins. Only disulfide reduction was shown to significantly perturb the protein, and resulted in considerably decreased adduct formation consistent with loss of tertiary/secondary structure. Cold denaturation experiments demonstrated that wild-type Ltn is the most temperature sensitive of the three proteins. Examination of the higher charge states in all experiments, which are presumed to represent transition state structures between Ltn-10 and Ltn-40, reveals increased 18C6 attachment relative to the more folded structures. This observation is consistent with increased competitive intramolecular hydrogen bonding, which may guide the transition. Experiments examining the gas phase structures revealed that all three proteins can be structurally distinguished in the gas phase. In addition, the gas phase experiments enabled identification of preferred adduct binding sites.
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Affiliation(s)
- Qingyu Sun
- Department of Chemistry, University of California, Riverside, CA 92521 USA
| | - Robert C. Tyler
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI 53226 USA
| | - Brian F. Volkman
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI 53226 USA
| | - Ryan R. Julian
- Department of Chemistry, University of California, Riverside, CA 92521 USA
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21
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Goel A, Tripet BP, Tyler RC, Nebert LD, Copié V. Backbone amide dynamics studies of Apo-L75F-TrpR, a temperature-sensitive mutant of the tryptophan repressor protein (TrpR): comparison with the (15)N NMR relaxation profiles of wild-type and A77V mutant Apo-TrpR repressors. Biochemistry 2010; 49:8006-19. [PMID: 20718459 DOI: 10.1021/bi100508u] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Backbone amide dynamics studies were conducted on a temperature-sensitive mutant (L75F-TrpR) of the tryptophan repressor protein (TrpR) of Escherichia coli in its apo (i.e., no l-tryptophan corepressor-bound) form. The (15)N NMR relaxation profiles of apo-L75F-TrpR were analyzed and compared to those of wild-type (WT) and super-repressor mutant (A77V) TrpR proteins, also in their apo forms. The (15)N NMR relaxation data ((15)N-T(1), (15)N-T(2), and heteronuclear (15)N-{(1)H}-nOe) recorded on all three aporepressors at a magnetic field strength of 600 MHz ((1)H Larmor frequency) were analyzed to extract dynamics parameters, including diffusion tensor ratios (D(∥)/D(⊥)), correlation times (τ(m)) for overall reorientations of the proteins in solution, reduced spectral density terms [J(eff)(0), J(0.87ω(H)), J(ω(N))], and generalized order parameters (S(2)), which report on protein internal motions on the picosecond to nanosecond and slower microsecond to millisecond chemical exchange time scales. Our results indicate that all three aporepressors exhibit comparable D(∥)/D(⊥) ratios and characteristic time constants, τ(m), for overall global reorientation, indicating that in solution, all three apoproteins display very similar overall shape, structure, and rotational diffusion properties. Comparison of (15)N NMR relaxation data, reduced spectral density profiles, and generalized S(2) order parameters indicated that these parameters are quite uniform for backbone amides positioned within the four (A-C and F) core α-helices of all three aporepressors. In contrast, small but noticeable differences in internal dynamics were observed for backbone amides located within the helix D-turn-helix E DNA-binding domain of the apo-TrpR proteins. The significance of these dynamics differences in terms of the biophysical characteristics and ligand binding properties of the three apo-TrpR proteins is discussed.
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Affiliation(s)
- Anupam Goel
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, USA
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22
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Abstract
par3 is a multiple-PDZ-containing scaffold protein that is central to the organization of an evolutionarily conserved cell polarity complex consisting of par3, par6, and aPKC. The ability of par3 PDZ domains to target various adhesion molecules and enzymes at the plasma membrane leads to the controlled localization of par6 and aPKC, which has firmly established its role in epithelial cell polarity. Of the numerous PDZ ligands associated with par3, interaction of its third PDZ domain with the class II ligand found within the C-terminal tail of vascular endothelial cadherin (VE-Cad) suggests a role in endothelial cell polarity as well, but the molecular details of the interaction are unknown. Previously determined structures of par3-PDZ3 bound to the class I ligand found within the C-terminal tail of the phosphoinositide phosphatase PTEN revealed two discrete binding sites: a canonical PDZ-ligand interaction site and a distal site involving charge-charge complements. Currently, it is unclear if par3-PDZ3 employs both canonical and distal binding modes in its association with VE-Cad or if these modes are unique to the PTEN interaction, suggesting a possible mechanism for ligand specificity within the polarity network. The structure of par3-PDZ3 bound to the C-terminal tail of VE-Cad presented in this work shows that both canonical and distal interactions are utilized in binding. Biophysical measurements using fluorescence polarization and two-dimensional NMR implicate the intermolecular charge pairing of aspartic acid 777 (VE-Cad) and arginine 609 (par3-PDZ3) as a crucial modulator of complex formation. Phosphorylation of VE-Cad at serine 776 increases its affinity for par3, demonstrating that post-translational modifications outside of the canonical carboxylate binding site can enhance PDZ-ligand interactions. Comparison of the VE-Cad and PTEN complexes highlights how the unique molecular architecture of par3-PDZ3 can accommodate both canonical and distal interaction modes that allow dual-class specificity for these two ligand types.
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Affiliation(s)
- Robert C Tyler
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
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23
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Tyler RC, Bitto E, Berndsen CE, Bingman CA, Singh S, Lee MS, Wesenberg GE, Denu JM, Phillips GN, Markley JL. Structure of Arabidopsis thaliana At1g77540 protein, a minimal acetyltransferase from the COG2388 family. Biochemistry 2007; 45:14325-36. [PMID: 17128971 PMCID: PMC2533278 DOI: 10.1021/bi0612059] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We describe X-ray crystal and NMR solution structures of the protein coded for by Arabidopsis thaliana gene At1g77540.1 (At1g77540). The crystal structure was determined to 1.15 A with an R factor of 14.9% (Rfree = 17.0%) by multiple-wavelength anomalous diffraction using sodium bromide derivatized crystals. The ensemble of NMR conformers was determined with protein samples labeled with 15N and 13C + 15N. The X-ray structure and NMR ensemble were closely similar with rmsd 1.4 A for residues 8-93. At1g77540 was found to adopt a fold similar to that of GCN5-related N-acetyltransferases. Enzymatic activity assays established that At1g77540 possesses weak acetyltransferase activity against histones H3 and H4. Chemical shift perturbations observed in 15N-HSQC spectra upon the addition of CoA indicated that the cofactor binds and identified its binding site. The molecular details of this interaction were further elucidated by solving the X-ray structure of the At1g77540-CoA complex. This work establishes that the domain family COG2388 represents a novel class of acetyltransferase and provides insight into possible mechanistic roles of the conserved Cys76 and His41 residues of this family.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - John L. Markley
- To whom correspondence should be addressed: Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706. Telephone: (608) 263-9349. Fax: (608) 262-3759. E-mail:
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24
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Tyler RC, Aceti DJ, Bingman CA, Cornilescu CC, Fox BG, Frederick RO, Jeon WB, Lee MS, Newman CS, Peterson FC, Phillips GN, Shahan MN, Singh S, Song J, Sreenath HK, Tyler EM, Ulrich EL, Vinarov DA, Vojtik FC, Volkman BF, Wrobel RL, Zhao Q, Markley JL. Comparison of cell-based and cell-free protocols for producing target proteins from the Arabidopsis thaliana genome for structural studies. Proteins 2006; 59:633-43. [PMID: 15789406 DOI: 10.1002/prot.20436] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We describe a comparative study of protein production from 96 Arabidopsis thaliana open reading frames (ORFs) by cell-based and cell-free protocols. Each target was carried through four pipeline protocols used by the Center for Eukaryotic Structural Genomics (CESG), one for the production of unlabeled protein to be used in crystallization trials and three for the production of 15N-labeled proteins to be analyzed by 1H-15N NMR correlation spectroscopy. Two of the protocols involved Escherichia coli cell-based and two involved wheat germ cell-free technology. The progress of each target through each of the protocols was followed with all failures and successes noted. Failures were of the following types: ORF not cloned, protein not expressed, low protein yield, no cleavage of fusion protein, insoluble protein, protein not purified, NMR sample too dilute. Those targets that reached the goal of analysis by 1H-15N NMR correlation spectroscopy were scored as HSQC+ (protein folded and suitable for NMR structural analysis), HSQC+/- (protein partially disordered or not in a single stable conformational state), HSQC- (protein unfolded, misfolded, or aggregated and thus unsuitable for NMR structural analysis). Targets were also scored as X- for failing to crystallize and X+ for successful crystallization. The results constitute a rich database for understanding differences between targets and protocols. In general, the wheat germ cell-free platform offers the advantage of greater genome coverage for NMR-based structural proteomics whereas the E. coli platform when successful yields more protein, as currently needed for crystallization trials for X-ray structure determination.
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Affiliation(s)
- Robert C Tyler
- Center for Eukaryotic Structural Genomics, University of Wisconsin-Madison, Wisconsin 53706, USA
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25
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Song J, Tyler RC, Lee MS, Tyler EM, Markley JL. Solution structure of isoform 1 of Roadblock/LC7, a light chain in the dynein complex. J Mol Biol 2005; 354:1043-51. [PMID: 16289575 DOI: 10.1016/j.jmb.2005.10.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2005] [Accepted: 10/05/2005] [Indexed: 10/25/2022]
Abstract
Roadblock/LC7 is a member of a class of dynein light chains involved in regulating the function of the dynein complex. We have determined the three-dimensional structure of isoform 1 of the mouse Roadblock/LC7 cytoplasmic dynein light chain (robl1_mouse) by NMR spectroscopy. In contrast to a previously reported NMR structure of the human homolog with 96% sequence identity (PDB 1TGQ), which showed the protein as a monomer, our results indicate clearly that robl1 exists as a symmetric homodimer. The two beta3-strands pair with each other and form a continuous ten-stranded beta-sheet. The 25-residue alpha2-helix from one subunit packs antiparallel to that of the other subunit on the face of the beta-sheet. Zipper-like hydrophobic contacts between the two helices serve to stabilize the dimer. Through an NMR titration experiment, we localized the site on robl1_mouse that interacts with the 40 residue peptide spanning residues 243 through 282 of IC74-1_rat. These results provide physical evidence for a symmetrical interaction between dimeric robl1 and the two molecules of IC74-1 in the dynein complex.
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Affiliation(s)
- Jikui Song
- Center for Eukaryotic Structural Genomics, Department of Biochemistry, University of Wisconsin-Madison, WI 53706-1544, USA
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26
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Singh S, Tonelli M, Tyler RC, Bahrami A, Lee MS, Markley JL. Three-dimensional structure of the AAH26994.1 protein from Mus musculus, a putative eukaryotic Urm1. Protein Sci 2005; 14:2095-102. [PMID: 16046629 PMCID: PMC2279321 DOI: 10.1110/ps.051577605] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
We have used NMR spectroscopy to determine the solution structure of protein AAH26994.1 from Mus musculus and propose that it represents the first three-dimensional structure of a ubiquitin-related modifier 1 (Urm1) protein. Amino acid sequence comparisons indicate that AAH26994.1 belongs to the Urm1 family of ubiquitin-like modifier proteins. The best characterized member of this family has been shown to be involved in nutrient sensing, invasive growth, and budding in yeast. Proteins in this family have only a weak sequence similarity to ubiquitin, and the structure of AAH26994.1 showed a much closer resemblance to MoaD subunits of molybdopterin synthases (known structures are of three bacterial MoaD proteins with 14%-26% sequence identity to AAH26994.1). The structures of AAH26994.1 and the MoaD proteins each contain the signature ubiquitin secondary structure fold, but all differ from ubiquitin largely in regions outside of this fold. This structural similarity bolsters the hypothesis that ubiquitin and ubiquitin-related proteins evolved from a protein-based sulfide donor system of the molybdopterin synthase type.
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Affiliation(s)
- Shanteri Singh
- Center for Eukaryotic Structural Genomics, Department of Biochemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706-1544, USA
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Singh S, Cornilescu CC, Tyler RC, Cornilescu G, Tonelli M, Lee MS, Markley JL. Solution structure of a late embryogenesis abundant protein (LEA14) from Arabidopsis thaliana, a cellular stress-related protein. Protein Sci 2005; 14:2601-9. [PMID: 16155204 PMCID: PMC2253292 DOI: 10.1110/ps.051579205] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
We report the three-dimensional structure of a late embryogenesis abundant (LEA) protein from Arabidopsis thaliana gene At1g01470.1. This protein is a member of Pfam cluster PF03168, and has been classified as a LEA14 protein. LEA proteins are expressed under conditions of cellular stress, such as desiccation, cold, osmotic stress, and heat. The structure, which was determined by NMR spectroscopy, revealed that the At1g01470.1 protein has an alphabeta-fold consisting of one alpha-helix and seven beta-strands that form two antiparallel beta-sheets. The closest structural homologs were discovered to be fibronectin Type III domains, which have <7% sequence identity. Because fibronectins from animal cells have been shown to be involved in cell adhesion, cell motility, wound healing, and maintenance of cell shape, it is interesting to note that in plants wounding or stress results in the overexpression of a protein with fibronectin Type III structural features.
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Affiliation(s)
- Shanteri Singh
- Center for Eukaryotic Structural Genomics, University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI 53706, USA
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Tyler RC, Sreenath HK, Singh S, Aceti DJ, Bingman CA, Markley JL, Fox BG. Auto-induction medium for the production of [U-15N]- and [U-13C, U-15N]-labeled proteins for NMR screening and structure determination. Protein Expr Purif 2005; 40:268-78. [PMID: 15766868 DOI: 10.1016/j.pep.2004.12.024] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2004] [Revised: 12/22/2004] [Indexed: 10/26/2022]
Abstract
Protocols have been developed and applied for the high-throughput production of [U-15N]- or [U-13C-, U-15N]-labeled proteins using the conditional methionine auxotroph Escherichia coli B834. The large-scale growth and expression uses a chemically defined auto-induction medium containing salts and trace metals, vitamins including vitamin B12, and glucose, glycerol, and lactose. The results from nine expression trials in 2-L of the auto-induction medium (500 mL in each of four polyethylene terephthalate beverage bottles) gave an average final optical density at 600 nm of approximately 5, an average wet cell mass yield of approximately 9.5 g L(-1), and an average yield of approximately 20 mg of labeled protein in the six instances in which proteolysis of the fusion protein was observed. Correlations between the cell mass recovered, the level of protein expression, and the relative amounts of glucose, glycerol, and lactose in the auto-induction medium were noted. Mass spectral analysis showed that the purified proteins contained both 15N and 13C at levels greater than 95%. 1H-15N heteronuclear single quantum correlation spectroscopy as well as 13C; 15N-edited spectroscopy showed that the purified [U-15N]- and [U-13C, U-15N]-labeled proteins were suitable for structure analysis.
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Affiliation(s)
- Robert C Tyler
- Department of Biochemistry, Center for Eukaryotic Structural Genomics, University of Wisconsin-Madison, 433 Babcock Drive, Madison, WI 53706-1549, USA
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Perez-Marrero R, Tyler RC. A subcutaneous delivery system for the extended release of leuprolide acetate for the treatment of prostate cancer. Expert Opin Pharmacother 2005; 5:447-57. [PMID: 14996640 DOI: 10.1517/14656566.5.2.447] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Following Huggins' original observation of the dependence of the prostate on androgens, testosterone suppression by either orchiectomy or oestrogen compounds (e.g., diethylstilbesterol [DES]) became the standard palliative treatment for advanced prostate cancer. Early studies showed testosterone suppression improved symptoms and patient survival by several months but was not curative. In addition, DES treatment resulted in significant cardiovascular morbidity and mortality from increased thrombotic events. Thus, both orchiectomy and DES were indicated for palliation in late stage disease, but were considered too extreme for earlier stage disease. The discovery of the hypothalamic peptide, luteinising hormone releasing hormone (LHRH), and its stimulatory release of luteinising hormone (LH) from the pituitary gland led to the synthesis of LHRH analogues (i.e., hormone therapy). LHRH analogues (e.g., leuprolide acetate) desensitise and downregulate pituitary LHRH receptors, thus reducing LH synthesis and release. The reduced release, in turn, decreases testosterone levels to those observed in DES-treated and orchiectomised patients. In contrast, LHRH analogues do not increase cardiovascular events. Therefore, leuprolide acetate therapy has been adopted as a safer alternative to DES and is considered to be generally reversible. This increased safety has allowed LHRH therapy to be applied in earlier stage prostate cancer. Recent studies have shown decreased rates of biochemical failure and a potential for increased patient survival with hormone therapy in conjunction with radical prostatectomy or radiation therapy. This article will focus on the literature supporting early, adjuvant LHRH therapy and Eligard 7.5 mg, a new depot formulation of leuprolide acetate that uses the Atrigel drug delivery system, causing an increase in bioavailability and optimising testosterone suppression - two key features of depot hormone suppression.
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Song J, Tyler RC, Wrobel RL, Frederick RO, Vojtek FC, Jeon WB, Lee MS, Markley JL. Solution structure of At3g04780.1-des15, an Arabidopsis thaliana ortholog of the C-terminal domain of human thioredoxin-like protein. Protein Sci 2005; 14:1059-63. [PMID: 15741346 PMCID: PMC2253455 DOI: 10.1110/ps.041246805] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The structure of At3g04780.1-des15, an Arabidopsis thaliana ortholog of the C-terminal domain of human thioredoxin-like protein, was determined by NMR spectroscopy. The structure is dominated by a beta-barrel sandwich. A two-stranded anti-parallel beta-sheet, which seals off one end of the beta-barrel, is flanked by two flexible loops rich in acidic amino acids. Although this fold often provides a ligand binding site, the structure did not reveal an appreciable cavity inside the beta-barrel. The three-dimensional structure of At3g04780.1-des15 provides an entry point for understanding its functional role and those of its mammalian homologs.
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Affiliation(s)
- Jikui Song
- Center for Eukaryotic Structural Genomics, Department of Biochemistry, 433 Babcock Drive, University of Wisconsin-Madison, Madison, WI 53706-1544, USA
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Song J, Vinarov D, Tyler EM, Shahan MN, Tyler RC, Markley JL. Hypothetical protein At2g24940.1 from Arabidopsis thaliana has a cytochrome b5 like fold. J Biomol NMR 2004; 30:215-218. [PMID: 15702529 DOI: 10.1023/b:jnmr.0000048943.34504.29] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
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Sartor O, Dineen MK, Perez-Marreno R, Chu FM, Carron GJ, Tyler RC. An eight-month clinical study of LA-2575 30.0 mg: a new 4-month, subcutaneous delivery system for leuprolide acetate in the treatment of prostate cancer. Urology 2003; 62:319-23. [PMID: 12893343 DOI: 10.1016/s0090-4295(03)00330-3] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVES To investigate the safety, efficacy, and pharmacokinetics of a new 4-month subcutaneous depot of leuprolide acetate in patients with prostate cancer. METHODS Ninety patients diagnosed with adenocarcinoma of the prostate were enrolled in an open-label, multicenter study. LA-2575 30.0 mg was administered subcutaneously once every 4 months for 8 months. The primary efficacy parameter was a serum testosterone level of 50 ng/dL or less. The pharmacokinetics of leuprolide acetate were analyzed in the first 24 enrolled patients. The values are reported as the mean +/- standard error. RESULTS Of 90 enrolled patients, 82 (91%) completed the 8-month study. Eight patients voluntarily withdrew from the study for the following reasons: nonmedical reasons (n = 3), treatment-related adverse events (n = 3), disease progression (n = 1), and cardiovascular disease (n = 1). By day 28, 85 (94%) of the 90 patients had achieved a serum testosterone level less than 50 ng/dL. At study completion, 88 (98%) of the 90 patients had a testosterone value less than the castrate level (mean 12.4 +/- 0.8 ng/dL), with 81 (90%) at less than 20 ng/dL. From baseline to month 6, the mean luteinizing hormone level had decreased from 7.51 +/- 0.69 mIU/mL to 0.12 +/- 0.02 mIU/mL. The mean prostate-specific antigen level had decreased 90% from 13.2 +/- 2.0 ng/mL at baseline to 1.3 +/- 0.3 ng/mL at 8 months. No clinically significant flare reactions were observed. The most common treatment-related adverse event was mild hot flashes. CONCLUSIONS LA-2575 30.0-mg depot consistently produced and maintained safe and effective suppression of serum testosterone, with total serum testosterone concentrations well below the medical castrate level of less than 50 ng/dL.
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Affiliation(s)
- Oliver Sartor
- Louisiana State University School of Medicine, New Orleans, Louisiana, USA
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Perez-Marreno R, Chu FM, Gleason D, Loizides E, Wachs B, Tyler RC. A six-month, open-label study assessing a new formulation of leuprolide 7.5 mg for suppression of testosterone in patients with prostate cancer. Clin Ther 2002; 24:1902-14. [PMID: 12501882 DOI: 10.1016/s0149-2918(02)80087-x] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE The safety, efficacy, and pharmacokinetics of monthly subcutaneous injections of a new leuprolide acetate (LA) depot formulation were investigated in patients with advanced prostate cancer. METHODS The 2-part, 6-month (168-day), open-label, multicenter study enrolled male patients diagnosed with adenocarcinoma of the prostate (Jewett stage C or D). LA-2500 7.5-mg (a new subcutaneous depot formulation containing 7.5 mg of LA) injections were administered at monthly (28-day) intervals. The primary efficacy parameter was total serum testosterone level. A breakthrough response was defined as a single testosterone measurement > 50 ng/dL after achieving castration testosterone levels. Testosterone was isolated from sera by alumina column chromatography and measured by radioimmunoassay (RIA). LA was purified by solid-phase extraction and high-performance liquid chromatography and was then quantitated by RIA. RESULTS One hundred seventeen of the 120 enrolled patients completed the 6-month study. Three patients withdrew for reasons not related to treatment. LA had a mean (SD) maximal concentration of 26.3 (12.6) ng/mL at 4.66 (1.44) hours and was detected for a mean of 37 days (range, 28-49 days). By day 28, 94.1% (112/119) of the patients achieved medical castration (serum testosterone < or = 50 ng/dL). By day 42, 100.0% (118/118) of the patients remaining in the study had serum testosterone levels < or = 50 ng/dL and 97.5% (115/118) had levels < or = 20 ng/dL. At study completion, the mean (SD) serum testosterone level was 6.12 (4.3) ng/dL (range, 3.0-27.0 ng/dL). No breakthrough or acute-on-chronic responses were reported throughout the study. From baseline to month 6, mean (SD) luteinizing hormone level decreased from 8.0 (7.3) mIU/mL to 0.09(0.1) mIU/mL, and mean (SD) prostate-specific antigen level decreased from 32.9 (86.3) ng/mL to 3.2 (12.0) ng/mL. Treatment-related adverse events were reported by 74.2% (89/120) of patients, the most common being hot flashes (56.7%). CONCLUSION This 6-month, open-label, noncontrolled study showed LA-2500 7.5-mg depot was well tolerated and maintained testosterone suppression (< or = 50 ng/dL) in the patients completing the study without any testosterone breakthrough responses.
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Chu FM, Jayson M, Dineen MK, Perez R, Harkaway R, Tyler RC. A clinical study of 22.5 mg. La-2550: A new subcutaneous depot delivery system for leuprolide acetate for the treatment of prostate cancer. J Urol 2002; 168:1199-203. [PMID: 12187267 DOI: 10.1016/s0022-5347(05)64625-3] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
PURPOSE The safety, efficacy and pharmacokinetics of a unique 3-month subcutaneous depot of leuprolide acetate were investigated in patients with prostate cancer. MATERIALS AND METHODS This open label, noncomparative, 6-month multicenter study enrolled 117 patients diagnosed with adenocarcinoma of the prostate. LA-2550 (22.5 mg. depot) (Atrix Laboratories, Fort Collins, Colorado) was administered subcutaneously once every 3 months. The primary efficacy parameter was serum testosterone 50 ng./dl. or less. Pharmacokinetics were analyzed in a subset of 22 patients. RESULTS Of the 117 enrolled patients 111 (98%) completed the 6-month study. Five patients withdrew for nontreatment related events and 1 was withdrawn because he received less than a full dose of the study drug. By day 28, 98% of patients had serum testosterone 50 ng./dl. or less and 84% had achieved 20 ng./dl. or less. By day 35 all patients had 50 ng./dl. or less testosterone. A patient with a breakthrough response after testosterone suppression on day 49 (112 ng./dl.) regained suppression (27 ng./dl.) 14 days after the second injection (day 98). At study completion all patients had 50 ng./dl. or less testosterone (mean plus or minus standard error of mean 10.1 +/- 0.07) and 104 of the 111 (94%) had 20 ng./dl. or less. From baseline to month 6 mean luteinizing hormone decreased from 9.2 +/- 1.1 to 0.08 +/- 0.01 mIU/ml. and mean prostate specific antigen decreased more than 98%. No flare reactions were observed and patient assessments of bone pain and urinary symptoms were unchanged. The most common treatment related adverse event was hot flashes, which were mild in 57% of cases, moderate in 12% and severe in 0%. CONCLUSIONS LA-2550 (22.5 mg. depot) produced and maintained safe and effective suppression of serum testosterone to well below the medical castrate level of 50 ng./dl. or less.
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Affiliation(s)
- Franklin M Chu
- San Bernardino Urological Associates, San Bernardino, California, USA
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Chu FM, Jayson M, Dineen MK, Perez R, Harkaway R, Tyler RC. A clinical study of 22.5 mg. La-2550: A new subcutaneous depot delivery system for leuprolide acetate for the treatment of prostate cancer. J Urol 2002; 168:1199-203. [PMID: 12187267 DOI: 10.1097/01.ju.0000023895.95963.1b] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE The safety, efficacy and pharmacokinetics of a unique 3-month subcutaneous depot of leuprolide acetate were investigated in patients with prostate cancer. MATERIALS AND METHODS This open label, noncomparative, 6-month multicenter study enrolled 117 patients diagnosed with adenocarcinoma of the prostate. LA-2550 (22.5 mg. depot) (Atrix Laboratories, Fort Collins, Colorado) was administered subcutaneously once every 3 months. The primary efficacy parameter was serum testosterone 50 ng./dl. or less. Pharmacokinetics were analyzed in a subset of 22 patients. RESULTS Of the 117 enrolled patients 111 (98%) completed the 6-month study. Five patients withdrew for nontreatment related events and 1 was withdrawn because he received less than a full dose of the study drug. By day 28, 98% of patients had serum testosterone 50 ng./dl. or less and 84% had achieved 20 ng./dl. or less. By day 35 all patients had 50 ng./dl. or less testosterone. A patient with a breakthrough response after testosterone suppression on day 49 (112 ng./dl.) regained suppression (27 ng./dl.) 14 days after the second injection (day 98). At study completion all patients had 50 ng./dl. or less testosterone (mean plus or minus standard error of mean 10.1 +/- 0.07) and 104 of the 111 (94%) had 20 ng./dl. or less. From baseline to month 6 mean luteinizing hormone decreased from 9.2 +/- 1.1 to 0.08 +/- 0.01 mIU/ml. and mean prostate specific antigen decreased more than 98%. No flare reactions were observed and patient assessments of bone pain and urinary symptoms were unchanged. The most common treatment related adverse event was hot flashes, which were mild in 57% of cases, moderate in 12% and severe in 0%. CONCLUSIONS LA-2550 (22.5 mg. depot) produced and maintained safe and effective suppression of serum testosterone to well below the medical castrate level of 50 ng./dl. or less.
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Affiliation(s)
- Franklin M Chu
- San Bernardino Urological Associates, San Bernardino, California, USA
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Tyler RC, Fagan KA, Unfer RC, Gorman C, McClarrion M, Bullock C, Rodman DM. Vascular inflammation inhibits gene transfer to the pulmonary circulation in vivo. Am J Physiol 1999; 277:L1199-204. [PMID: 10600891 DOI: 10.1152/ajplung.1999.277.6.l1199] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We report gene transfer to the normal and injured murine pulmonary circulation via systemic (intravascular) and airway (intratracheal) delivery of novel polycationic liposomes (imidazolium chloride, imidazolinium chloride-cholesterol, and ethyl phosphocholine). With use of the reporter genes chloramphenicol acetyltransferase (CAT) or human placental alkaline phosphatase (hpAP), intravascular injection of lipid-DNA complexes resulted in gene expression primarily in the lung, with lesser expression in the heart (11% of lung, P < 0.05) and spleen (8% of lung, P < 0.05). Histochemical staining for the hpAP reporter gene showed localized transgene expression in the microvascular endothelium. Monocrotaline (80 mg/kg body wt sc) treatment produced endovascular inflammation and reduced lung CAT activity (2 days postintravascular transfection) by 75 +/- 8 and 86 +/- 6% at 7 and 21 days, respectively, after monocrotaline (P < 0. 05). Despite the apparent decrease in functional CAT protein, Southern blot analysis suggested maintained plasmid delivery, whereas quantitative PCR (TaqMan) showed decreased CAT mRNA levels in monocrotaline mice. In contrast, intratracheal delivery of lipid-DNA complexes showed enhanced CAT expression in monocrotaline mice. Transfection in alternate pulmonary vascular disorders was studied by inducing hypoxic pulmonary hypertension (4 wk at barometric pressure of 410 mmHg). Efficiency and duration of gene transfer, assessed by CAT activity, were similar in pulmonary hypertensive and normal lungs. We conclude that imidazolinium-derived polycationic liposomes provide a means of relatively selective and efficient gene transfer to the normal and injured murine microvascular circulation, although translation of transgene mRNA may be reduced by preexisting endothelial injury.
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Affiliation(s)
- R C Tyler
- Cardiovascular Pulmonary Research Laboratory, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA
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Fagan KA, Tyler RC, Sato K, Fouty BW, Morris KG, Huang PL, McMurtry IF, Rodman DM. Relative contributions of endothelial, inducible, and neuronal NOS to tone in the murine pulmonary circulation. Am J Physiol 1999; 277:L472-8. [PMID: 10484454 DOI: 10.1152/ajplung.1999.277.3.l472] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Nitric oxide plays an important role in modulating pulmonary vascular tone. All three isoforms of nitric oxide synthase (NOS), neuronal (nNOS, NOS I), inducible (iNOS, NOS II), and endothelial (eNOS, NOS III), are expressed in the lung. Recent reports have suggested an important role for eNOS in the modulation of pulmonary vascular tone chronically; however, the relative contribution of the three isoforms to acute modulation of pulmonary vascular tone is uncertain. We therefore tested the effect of targeted disruption of each isoform on pulmonary vascular reactivity in transgenic mice. Isolated perfused mouse lungs were used to evaluate the effect of selective loss of pulmonary nNOS, iNOS, and eNOS with respect to hypoxic pulmonary vasoconstriction (HPV) and endothelium-dependent and -independent vasodilation. eNOS null mice had augmented HPV (225 +/- 65% control, P < 0.02, mean +/- SE) and absent endothelium-dependent vasodilation, whereas endothelium-independent vasodilation was preserved. HPV was minimally elevated in iNOS null mice and normal in nNOS null mice. Both nNOS and iNOS null mice had normal endothelium-dependent vasodilation. In wild-type lungs, nonselective NOS inhibition doubled HPV, whereas selective iNOS inhibition had no detectable effect. In intact, lightly sedated mice, right ventricular systolic pressure was elevated in eNOS-deficient (42.3 +/- 1.2 mmHg, P < 0.001) and, to a lesser extent, in iNOS-deficient (37.2 +/- 0.8 mmHg, P < 0.001) mice, whereas it was normal in nNOS-deficient mice (30.9 +/- 0.7 mmHg, P = not significant) compared with wild-type controls (31.3 +/- 0.7 mmHg). We conclude that in the normal murine pulmonary circulation 1) nNOS does not modulate tone, 2) eNOS-derived nitric oxide is the principle mediator of endothelium-dependent vasodilation in the pulmonary circulation, and 3) both eNOS and iNOS play a role in modulating basal tone chronically.
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Affiliation(s)
- K A Fagan
- Cardiovascular Pulmonary Research Laboratory, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA.
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Tyler RC, Muramatsu M, Abman SH, Stelzner TJ, Rodman DM, Bloch KD, McMurtry IF. Variable expression of endothelial NO synthase in three forms of rat pulmonary hypertension. Am J Physiol 1999; 276:L297-303. [PMID: 9950892 DOI: 10.1152/ajplung.1999.276.2.l297] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Endothelial nitric oxide (NO) synthase (eNOS) mRNA and protein and NO production are increased in hypoxia-induced hypertensive rat lungs, but it is uncertain whether eNOS gene expression and activity are increased in other forms of rat pulmonary hypertension. To investigate these questions, we measured eNOS mRNA and protein, eNOS immunohistochemical localization, perfusate NO product levels, and NO-mediated suppression of resting vascular tone in chronically hypoxic (3-4 wk at barometric pressure of 410 mmHg), monocrotaline-treated (4 wk after 60 mg/kg), and fawn-hooded (6-9 mo old) rats. eNOS mRNA levels (Northern blot) were greater in hypoxic and monocrotaline-treated lungs (130 and 125% of control lungs, respectively; P < 0.05) but not in fawn-hooded lungs. Western blotting indicated that eNOS protein levels increased to 300 +/- 46% of control levels in hypoxic lungs (P < 0.05) but were decreased by 50 +/- 5 and 60 +/- 11%, respectively, in monocrotaline-treated and fawn-hooded lungs (P < 0.05). Immunostaining showed prominent eNOS expression in small neomuscularized arterioles in all groups, whereas perfusate NO product levels increased in chronically hypoxic lungs (3.4 +/- 1.4 microM; P < 0.05) but not in either monocrotaline-treated (0.7 +/- 0.3 microM) or fawn-hooded (0.45 +/- 0.1 microM) lungs vs. normotensive lungs (0.12 +/- 0.07 microM). All hypertensive lungs had increased baseline perfusion pressure in response to nitro-L-arginine but not to the inducible NOS inhibitor aminoguanidine. These results indicate that even though NO activity suppresses resting vascular tone in pulmonary hypertension, there are differences among the groups regarding eNOS gene expression and NO production. A better understanding of eNOS gene expression and activity in these models may provide insights into the regulation of this vasodilator system in various forms of human pulmonary hypertension.
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Affiliation(s)
- R C Tyler
- Cardiovascular Pulmonary Research Laboratory, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA
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Fagan KA, Fouty BW, Tyler RC, Morris KG, Hepler LK, Sato K, LeCras TD, Abman SH, Weinberger HD, Huang PL, McMurtry IF, Rodman DM. The pulmonary circulation of homozygous or heterozygous eNOS-null mice is hyperresponsive to mild hypoxia. J Clin Invest 1999; 103:291-9. [PMID: 9916141 PMCID: PMC407877 DOI: 10.1172/jci3862] [Citation(s) in RCA: 256] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Acute hypoxic vasoconstriction and development of hypoxic pulmonary hypertension (PHTN) are unique properties of the pulmonary circulation. The pulmonary endothelium produces vasoactive factors, including nitric oxide (NO), that modify these phenomena. We tested the hypothesis that NO produced by endothelial nitric oxide synthase (eNOS) modulates pulmonary vascular responses to hypoxia using mice with targeted disruption of the eNOS gene (eNOS-/-). Marked PHTN was found in eNOS-/- mice raised in mild hypoxia when compared with either controls or eNOS-/- mice raised in conditions simulating sea level. We found an approximate twofold increase in partially and fully muscularized distal pulmonary arteries in eNOS-/- mice compared with controls. Consistent with vasoconstriction being the primary mechanism of PHTN, however, acute inhalation of 25 ppm NO resulted in normalization of RV pressure in eNOS-/- mice. In addition to studies of eNOS-/- mice, the dose-effect of eNOS was tested using heterozygous eNOS+/- mice. Although the lungs of eNOS+/- mice had 50% of normal eNOS protein, the response to hypoxia was indistinguishable from that of eNOS-/- mice. We conclude that eNOS-derived NO is an important modulator of the pulmonary vascular response to chronic hypoxia and that more than 50% of eNOS expression is required to maintain normal pulmonary vascular tone.
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Affiliation(s)
- K A Fagan
- Cardiovascular Pulmonary Research Laboratory, University of Colorado Health Sciences Center, Denver 80262, USA.
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Le Cras TD, Tyler RC, Horan MP, Morris KG, McMurty IF, Johns RA, Abman SH. Effects of chronic hypoxia and altered hemodynamics on endothelial nitric oxide synthase and preproendothelin-1 expression in the adult rat lung. Chest 1998; 114:35S-36S. [PMID: 9676618 DOI: 10.1378/chest.114.1_supplement.35s-a] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Affiliation(s)
- T D Le Cras
- Department of Pediatrics, University of Colorado Health Sciences Center, Denver, USA
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Le Cras TD, Tyler RC, Horan MP, Morris KG, Tuder RM, McMurtry IF, Johns RA, Abman SH. Effects of chronic hypoxia and altered hemodynamics on endothelial nitric oxide synthase expression in the adult rat lung. J Clin Invest 1998; 101:795-801. [PMID: 9466974 PMCID: PMC508627 DOI: 10.1172/jci786] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Mechanisms that regulate endothelial nitric oxide synthase (eNOS) expression in normal and hypoxic pulmonary circulation are poorly understood. Lung eNOS expression is increased after chronic hypoxic pulmonary hypertension in rats, but whether this increase is due to altered hemodynamics or to hypoxia is unknown. Therefore, to determine the effect of blood flow changes on eNOS expression in the normal pulmonary circulation, and to determine whether the increase in eNOS expression after chronic hypoxia is caused by hemodynamic changes or low oxygen tension, we compared eNOS expression in the left and right lungs of normoxic and chronically hypoxic rats with surgical stenosis of the left pulmonary artery (LPA). LPA stenosis in normoxic rats reduced blood flow to the left lung from 9.8+/-0.9 to 0.8+/-0.4 ml/100 mg/min (sham surgery controls vs. LPA stenosis, P < 0.05), but there was not a significant increase in right lung blood flow. When compared with the right lung, eNOS protein and mRNA content in the left lung was decreased by 32+/-7 and 54+/-13%, respectively (P < 0.05), and right lung eNOS protein content was unchanged. After 3 wk of hypoxia, LPA stenosis reduced blood flow to the left lung from 5.8+/-0.6 to 1.5+/-0.4 ml/100 mg/min, and increased blood flow to the right lung from 5.8+/-0.5 to 10.0+/-1.4 ml/ 100 mg/min (sham surgery controls vs. LPA stenosis, P < 0.05). Despite reduced flow and pressure to the left lung and increased flow and pressure to the right lung, left and right lung eNOS protein and mRNA contents were not different. There were also no differences in lung eNOS protein levels when compared with chronically hypoxic sham surgery controls (P > 0.05). We conclude that reduction of pulmonary blood flow decreases eNOS mRNA and protein expression in normoxic adult rat lungs, and that hypoxia increases eNOS expression independently of changes in hemodynamics. These findings demonstrate that hemodynamic forces maintain eNOS content in the normoxic pulmonary circulation of the adult rat, and suggest that chronic hypoxia increases eNOS expression independently of changes in hemodynamics.
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Affiliation(s)
- T D Le Cras
- Pediatric Heart Lung Center, Department of Pediatrics, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA.
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Tyler RC, Bullock C, Lapuz C, Gorman C, Hepler LK, Tudor RM, McMurtry IF, Rodman DM. Polycationic lipid-mediated gene transfer to the abnormal pulmonary circulation. Chest 1997; 111:122S-123S. [PMID: 9184558 DOI: 10.1378/chest.111.6_supplement.122s] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Affiliation(s)
- R C Tyler
- Cardiovascular Research Laboratory, University of Colorado Health Sciences Center, Denver, USA
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Muramatsu M, Tyler RC, Gutkowska J, Klinger JR, Hill NS, Rodman DM, McMurtry IF. Atrial natriuretic peptide accounts for increased cGMP in hypoxia-induced hypertensive rat lungs. Am J Physiol 1997; 272:L1126-32. [PMID: 9227514 DOI: 10.1152/ajplung.1997.272.6.l1126] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Perfusate levels of nitric oxide (NO)-containing compounds and guanosine 3',5'-cyclic monophosphate (cGMP) are increased in hypoxia-induced hypertensive rat lungs. To test if increased cGMP was due to NO stimulation of soluble guanylate cyclase (sGC), we examined effects of inhibition of NO synthase with N omega-nitro-L-arginine (L-NNA) on perfusate accumulation of cGMP in physiological salt solution (PSS)-perfused hypertensive lungs isolated from rats exposed for 3-4 wk to hypobaric hypoxia. Because 200 microM L-NNA did not reduce cGMP, we next examined inhibitors of other pathways of stimulation of either sGC or particulate GC (pGC). Neither 5 microM Zn-protophorphyrin, an inhibitor of CO production by heme oxygenase, nor 10 mM aminotriazole, an inhibitor of H2O2 metabolism by catalase, reduced perfusate cGMP. However, an antiserum to atrial natriuretic peptide (ANP; 100 microliters antiserum/30 ml PSS), to inhibit ANP activation of pGC, completely prevented accumulation of the nucleotide. ANP antiserum was also more effective than L-NNA in reducing lung tissue cGMP. In contrast, L-NNA but not ANP antiserum increased resting vascular tone. These results suggested that whereas ANP determined perfusate and tissue levels of cGMP, NO regulated vascular tone. To test if perfusate cGMP reflected ANP stimulation of pGC in endothelial rather than smooth muscle cells, we examined effects of 10 microM Zaprinast, an inhibitor of cGMP hydrolysis in smooth muscle but not endothelial cells, and found no increase of cGMP in hypertensive lungs. ANP levels were not elevated in hypertensive lungs, and it is unclear by what mechanism the ANP-stimulated activity of pGC is increased in hypertensive pulmonary vascular endothelial cells.
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Affiliation(s)
- M Muramatsu
- Department of Medicine, University of Colorado Health Sciences Center, Denver 80262, USA
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Abstract
Acute inhibition of endothelium-derived nitric oxide (NO) synthesis by L-arginine analogs such as N omega-nitro-L-arginine (L-NNA) has little effect on basal vascular tone in normal rat lungs but elicits marked vasoconstriction in hypertensive lungs. The NO-suppressible vasoconstriction is dependent on extracellular Ca2+ but is not mediated by L-type Ca2+ channels. This study tested whether the response was mediated by Ca2+ influx through receptor-operated channels, reverse Na+/Ca2+ exchange, or low-threshold voltage-gated (T-type) Ca2+ channels. We first examined whether SKF-96365, a blocker of receptor-operated Ca2+ channels, inhibited L-NNA-induced vasoconstriction in salt solution-perfused hypertensive lungs isolated from chronically hypoxic male rats (exposed to hypobaria of 410 mmHg for 3-5 wk). Whereas 50 microM SKF-96365 inhibited pressor responses to angiotensin II and acute hypoxia, it did not reduce vasoconstriction in response to 100 microM L-NNA. We next examined effects of pretreatment with Na+/Ca2+ exchange blockers and observed that L-NNA vasoconstriction was reduced by both 100 microM amiloride and 50 microM ethylisopropyl amiloride (EIPA). The third experiment showed that each of two different blockers of T-type Ca2+ channels, 10 microM Ro-40-5967 and 300 microM nordihydroguariaretic acid, inhibited L-NNA vasoconstriction and that the combination of EIPA and Ro-40-5967 did not cause more inhibition than did Ro-40-5967 alone. These results suggest that, whereas receptor-operated Ca2+ channels are not significantly involved in the mechanism of NO-suppressible vasoconstriction in hypertensive rat lungs, Ca2+ influx through reverse Na+/Ca2+ exchange and/or T-type Ca2+ channels may play a role. Because both amiloride and EIPA also inhibit T-type Ca2+ channels, we speculate that Ca2+ influx through these channels rather than through reverse Na+/Ca2+ exchange is an important mediator of the vasoconstriction.
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Affiliation(s)
- M Muramatsu
- Department of Medicine, University of Colorado Health Sciences Center, Denver 80262, USA
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Muramatsu M, Tyler RC, Rodman DM, McMurtry IF. Thapsigargin stimulates increased NO activity in hypoxic hypertensive rat lungs and pulmonary arteries. J Appl Physiol (1985) 1996; 80:1336-44. [PMID: 8926264 DOI: 10.1152/jappl.1996.80.4.1336] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
This study addressed the controversy of whether endothelium-derived nitric oxide (NO) activity is increased or decreased in the hypertensive pulmonary vasculature of chronically hypoxic rats. Thapsigargin, a receptor-independent Ca2+ agonist and stimulator of endothelial NO production, was used to compare NO-mediated vasodilation in perfused lungs and conduit pulmonary artery rings isolated from adult male rats either kept at Denver's altitude of 5,280 ft (control pulmonary normotensive rats) or exposed for 4-5 wk to the simulated altitude of 17,000 ft (chronically hypoxic pulmonary hypertensive rats). Under baseline conditions, thapsigargin (10(-9)-10(-7) M) caused vasodilation in hypertensive lungs and vasoconstriction in normotensive lungs. Whereas the sustained vasodilation in hypertensive lungs was reversed to vasoconstriction by the inhibitor of NO synthase N(omega)-nitro-L-arginine (L-NNA; 10(-4) M), a transient vasodilation to thapsigargin in acutely vasoconstricted normotensive lungs was potentiated. As measured by a chemiluminescence assay, the recirculated perfusate of hypertensive lungs accumulated considerably higher levels of NO-containing compounds that did normotensive lungs, and thapsigargin-induced stimulation of NO-containing compounds accumulation was greater in hypertensive than in normotensive lungs. Similarly, low concentrations of thapsigargin (10(-10)-10(-9) M) caused greater endothelium-dependent L-NNA-reversible relaxation of hypertensive than of normotensive pulmonary artery rings. The increased sensitivity of hypertensive arteries to thapsigargin-induced relaxation was eliminated in nominally Ca(2+)-free medium and was not mimicked by ryanodine, a releaser of intracellular Ca2+. These results with thapsigargin, which acts on endothelial cells to stimulate Ca2+ influx and a sustained rise in intracellular Ca2+ concentration, support the idea that pulmonary vascular endothelium-derived NO activity is increased rather than decreased in chronic hypoxia-induced pulmonary hypertension in rats.
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Affiliation(s)
- M Muramatsu
- Department of Medicine, University of Colorado Health Sciences Center, Denver 80262 USA
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