Biomedical subjects

Robert D Rosenberg

Publications and source records attributed to Robert D Rosenberg.

At least 19 recordsLinked to original sources

PubMed2006

Pathologic findings from the Breast Cancer Surveillance Consortium: population-based outcomes in women undergoing biopsy after screening mammography.

BACKGROUND: To the authors' knowledge, a comprehensive analysis of pathology outcomes after screening mammography, as it is practiced clinically in the U.S. general population, has not been performed. METHODS: Breast Cancer Surveillance Consortium data from 1996-2001 were used to identify pathology specimens that were obtained within 1 year of screening mammograms performed on 786,846 women ages 40-89 years. The pathology results were classified as invasive carcinoma, ductal carcinoma in situ (DCIS), or benign. The associations between overall pathology outcomes and invasive tumor size and lymph node status were analyzed by age and mammography assessment category. RESULTS: The rates of both recommending and performing a biopsy varied little with age. The 1,664,032 screening mammograms were followed by 26,748 known biopsies (1.6%) and 8815 diagnoses of breast carcinoma (0.53%). Overall, 81% of carcinomas were invasive, and 78% of those were pathologically lymph node-negative tumors, in contrast to the 66% prevalence observed in the Surveillance, Epidemiology, and End Results (SEER) data during the same period. Most invasive tumors measured between 0 mm and 10 mm (35%) or between 11 mm and 20 mm (36%) in greatest dimension, and 92% and 78% were lymph node-negative tumors, respectively: Biopsy results that were classified as malignant increased with age (P < 0.0001) and were most likely to follow Breast Imaging, Reporting, and Diagnosis System Category 5 and 4 assessments, respectively. Ductal hyperplasia (19.6%), fibroadenoma (18.5%), and other benign findings (56.1%) were the most common benign diagnoses. CONCLUSIONS: Pathologically negative lymph nodes were more prevalent in this mammographically screened population than in the overall SEER population. The prevalence of invasive carcinoma, DCIS, and benign findings presented herein establish a range of expected biopsy outcomes for women after screening mammography in the general U.S. population.

Adult↗

PubMed2006

Improving the concordance of mammography assessment and management recommendations.

PURPOSE: To retrospectively compare the concordance of initial and final assessment categories for mammograms with management recommendations made before and after the final rules of the Mammography Quality Standards Act (MQSA) were in effect for screening and diagnostic mammography. MATERIALS AND METHODS: The study included mammograms from 1996 to 2001 from the seven mammography registries of the Breast Cancer Surveillance Consortium (BCSC). The authors defined the pre-MQSA period as January 1, 1996-April 27, 1999, and the post-MQSA period as April 28, 1999-December 31, 2001 (2470151 screening and 194199 diagnostic mammograms). Assessment was cross-classified according to management recommendation. Changes in concordance between assessment and recommendation were evaluated by year and by period (before and after MQSA) for computer-linked data and for all data by using Pearson chi(2) test to evaluate differences. Mantel-Haenszel chi(2) test was used to measure change in concordance over time. Each registry and the BCSC Statistical Coordinating Center had a Federal Certificate of Confidentiality and approval from each institution's review board for protection of human subjects to collect and send data to coordinating center and conduct research with these data. Active consent was required at only one site in this HIPAA-compliant study. RESULTS: Concordance increased significantly in the post-MQSA period for Breast Imaging Reporting and Data System categories 3-5 assessments at both screening and diagnostic mammography. The most substantial improvements were in the use of the management recommendation for "additional imaging," which decreased from 41% in 1996 to 15% in 2001 for screening mammograms with an initial assessment of category 4 (P < .001). Recommendation for short-interval follow-up in women with screening mammograms with a category 3 final assessment increased from 51% in 1996 to 76% in 2001 (P < .001). Concordance for diagnostic mammograms assigned category 0 improved from 65% in the pre-MQSA period to 81% in the post-MQSA period (P < .001). CONCLUSION: This analysis demonstrates that over a relatively short period of time, major improvement in radiology reporting has occurred.

Breast Neoplasms↗

PubMed2006

Performance benchmarks for screening mammography.

PURPOSE: To retrospectively evaluate the range of performance outcomes of the radiologist in an audit of screening mammography by using a representative sample of U.S. radiologists to allow development of performance benchmarks for screening mammography. MATERIALS AND METHODS: Institutional review board approval was obtained, and study was HIPAA compliant. Informed consent was or was not obtained according to institutional review board guidelines. Data from 188 mammographic facilities and 807 radiologists obtained between 1996 and 2002 were analyzed from six registries from the Breast Cancer Surveillance Consortium (BCSC). Contributed data included demographic information, clinical findings, mammographic interpretation, and biopsy results. Measurements calculated were positive predictive values (PPVs) from screening mammography (PPV(1)), biopsy recommendation (PPV(2)), biopsy performed (PPV(3)), recall rate, cancer detection rate, mean cancer size, and cancer stage. Radiologist performance data are presented as 50th (median), 10th, 25th, 75th, and 90th percentiles and as graphic presentations by using smoothed curves. RESULTS: There were 2 580 151 screening mammographic studies from 1 117 390 women (age range, <30 to >/=80 years). The respective means and ranges of performance outcomes for the middle 50% of radiologists were as follows: recall rate, 9.8% and 6.4%-13.3%; PPV(1), 4.8% and 3.4%-6.2%; and PPV(2), 24.6% and 18.8%-32.0%. Mean cancer detection rate was 4.7 per 1000, and the median [corrected] mean size of invasive cancers was 13 mm. The range of performance outcomes for the middle 80% of radiologists also was presented. CONCLUSION: Community screening mammographic performance measurements of cancer outcomes for the majority of radiologists in the BCSC surpass performance recommendations. Recall rate for almost half of radiologists, however, is higher than the recommended rate.

Adult↗

PubMed2005

Physician predictors of mammographic accuracy.

BACKGROUND: The association between physician experience and the accuracy of screening mammography in community practice is not well studied. We identified characteristics of U.S. physicians associated with the accuracy of screening mammography. METHODS: Data were obtained from the Breast Cancer Surveillance Consortium and the American Medical Association Master File. Unadjusted mammography sensitivity and specificity were calculated according to physician characteristics. We modeled mammography sensitivity and specificity by multivariable logistic regression as a function of patient and physician characteristics. All statistical tests were two-sided. RESULTS: We studied 209 physicians who interpreted 1,220,046 screening mammograms from January 1, 1995, through December 31, 2000, of which 7143 (5.9 per 1000 mammograms) were associated with breast cancer within 12 months of screening. Each physician interpreted a mean of 6011 screening mammograms (95% confidence interval [CI] = 4998 to 6677), including a mean of 34 (95% CI = 28 to 40) from women diagnosed with breast cancer. The mean sensitivity was 77% (range = 29%-97%), and the mean false-positive rate was 10% (range = 1%-29%). After adjustment for the patient characteristics of those whose mammograms they interpreted, physician characteristics were strongly associated with specificity. Higher specificity was associated with at least 25 years (versus less than 10 years) since receipt of a medical degree (for physicians practicing for 25-29 years, odds ratio [OR] = 1.54, 95% CI = 1.14 to 2.08; P = .006), interpretation of 2500-4000 (versus 481-750) screening mammograms annually (OR = 1.30, 95% CI = 1.06 to 1.59; P = .011) and a high focus on screening mammography compared with diagnostic mammography (OR = 1.59, 95% CI = 1.37 to 1.82; P<.001). Higher overall accuracy was associated with more experience and with a higher focus on screening mammography. Compared with physicians who interpret 481-750 mammograms annually and had a low screening focus, physicians who interpret 2500-4000 mammograms annually and had a high screening focus had approximately 50% fewer false-positive examinations and detected a few less cancers. CONCLUSION: Raising the annual volume requirements in the Mammography Quality Standards Act might improve the overall quality of screening mammography in the United States.

Adult↗

PubMed2005

Association between mammography timing and measures of screening performance in the United States.

PURPOSE: To evaluate whether there is an association between the number of months since previous mammography (MSPM) and performance measures (sensitivity, specificity, recall rate, cancer detection rate, and positive predictive value) in women who underwent U.S. community-based screening mammography. MATERIALS AND METHODS: Data from seven registries (Breast Cancer Surveillance Consortium) and mammographic data and cancer outcome in regard to 1 213 754 screening mammographic examinations performed in 680 641 women who were 40-89 years old for the years 1996-2000 were used in this study. These data are submitted annually in a standard format to a central statistical coordinating center that is subject to institutional review board approval, quality control, and confidentiality standards. Performance measures were calculated for first and subsequent screening mammography. For subsequent mammography, performance measures were calculated according to categories of MSPM (9-15, 16-20, 21-27, and >/=28 months). Receiver operating characteristic and multivariable logistic regression analyses were conducted to test the association between the number of MSPM and performance measures. RESULTS: With increasing MSPM in each category from 9-15 to 28 months or more and for first mammographic examinations, respectively, there was increased sensitivity (70.9%, 75.7%, 85.4%, 82.5%, and 88.6%), decreased specificity (93.3%, 92.7%, 91.6%, 91.0%, and 85.9%), increased recall rate (7.0%, 7.6%, 8.8%, 9.4%, and 14.7%), and increased cancer detection rates (3.2, 3.5, 4.5, 4.6, and 6.1 per 1000 mammographic examinations). When the category of 9-15 MSPM was compared with that of 21-27 MSPM, there was a slight increase in positive predictive value from 4.6% to 5.1%. Confidence intervals were narrow and did not overlap. Age affected these associations for all performance measures except sensitivity. CONCLUSION: Performance measures increased as MSPM increased, except for specificity, which decreased. Time between mammograms is an important factor to consider when audits are reviewed or screening performance measures are compared.

Adult↗

PubMed2005

Performance benchmarks for diagnostic mammography.

PURPOSE: To evaluate a range of performance parameters pertinent to the comprehensive auditing of diagnostic mammography examinations, and to derive performance benchmarks therefrom, by pooling data collected from large numbers of patients and radiologists that are likely to be representative of mammography practice in the United States. MATERIALS AND METHODS: Institutional review board approval was met, informed consent was not required, and this study was Health Insurance Portability and Accountability Act compliant. Six mammography registries contributed data to the Breast Cancer Surveillance Consortium (BCSC), providing patient demographic and clinical information, mammogram interpretation data, and biopsy results from defined population-based catchment areas. The study involved 151 mammography facilities and 646 interpreting radiologists. The study population included women 18 years of age or older who underwent at least one diagnostic mammography examination between 1996 and 2001. Collected data were used to derive mean performance parameter values, including abnormal interpretation rate, positive predictive value (for abnormal interpretation, biopsy recommended, and biopsy performed), cancer diagnosis rate, invasive cancer size, and the percentages of minimal cancers, axillary node-negative invasive cancers, and stage 0 and I cancers. Additional benchmarks were derived for these performance parameters, including 10th, 25th, 50th (median), 75th, and 90th percentile values. RESULTS: The study involved 332,926 diagnostic mammography examinations. Mean performance parameter values were abnormal interpretation rate, 8.0%; positive predictive value for abnormal interpretation, 31.4%; positive predictive value for biopsy recommended, 31.5%; positive predictive value for biopsy performed, 39.5%; cancer diagnosis rate, 25.3 per 1000 examinations; invasive cancer size, 20.2 mm; percentage of minimal cancers, 42.0%; percentage of axillary node-negative invasive cancers, 73.6%; and percentage of stage 0 and I cancers, 62.4%. CONCLUSION: The presented BCSC outcomes data and performance benchmarks may be used by mammography facilities and individual radiologists to evaluate their own performance for diagnostic mammography as determined by means of periodic comprehensive audits.

Adult↗

PubMed2004

Biennial versus annual mammography and the risk of late-stage breast cancer.

BACKGROUND: Mammography screening may reduce breast cancer mortality by detecting cancers at an earlier stage. However, certain questions remain, including the ideal interval between mammograms. METHODS: We conducted an observational study using information collected by seven mammography registries across the United States to investigate whether women diagnosed with breast cancer after having screening mammograms separated by a 2-year interval (n = 2440) are more likely to be diagnosed with late-stage disease (positive lymph nodes or metastases) than women diagnosed with breast cancer after having screening mammograms separated by a 1-year interval (n = 5400). Analyses were stratified by age and breast density to clarify whether groups that have the poorest mammography sensitivity (i.e., women under age 50 years and those with mammographically dense breasts) would benefit most from annual screening. The subjects were women diagnosed with breast cancer between 1996 and 2001 who were 40-89 years old at their index mammographic examination (i.e., the most recent screen at or before breast cancer diagnosis). Data were analyzed by logistic regression, adjusting for race, ethnicity, family history of breast cancer, and mammography registry. RESULTS: Among women age 40-49 years at the index mammogram, those with a 2-year screening interval were more likely to have late-stage disease at diagnosis than those with a 1-year screening interval (28% versus 21%; odds ratio [OR] = 1.35, 95% confidence interval [CI] = 1.01 to 1.81). There was no increase in late-stage disease for women 50 years or older with a 2-year versus a 1-year screening interval (women age 50-59 years at index mammogram: OR = 0.97, 95% CI = 0.75 to 1.25; women age 60-69 years at index mammogram: OR = 0.99, 95% CI = 0.72 to 1.35; women age 70 years or older at index mammogram: OR = 0.88, 95% CI = 0.64 to 1.19). There was no indication that women with dense breasts would benefit more from a 1-year versus 2-year screening interval than women with fatty breasts. CONCLUSION: These findings may be useful for policy decisions about appropriate screening intervals and for use in statistical models that estimate the costs and benefits of mammography by age and screening interval.

Adult↗

PubMed2004

Role of heparan sulfate in dextral heart looping in chick.

Heparan sulfate (HS) has been shown to be involved in left-right asymmetry formation, including the process of dextral heart looping during embryonic development. The structural features of HS required in this process, however, have not been explored. In this study, we examined the structure of HS from the heart-forming regions (or heart fields) of Hamburger and Hamilton stage 5-9 chick embryos. No significant differences were found in HS to chondroitin sulfate (CS) ratio, HS chain length, or [35S] sulfate incorporation at HS disaccharide level between the left and the right heart fields. Compared to other parts of the embryo, however, lower ratio of HS to CS, shorter HS chain length, and higher [35S] sulfate incorporation at 6-O position of the glucosamine residue in the HS chains were observed in the heart-forming regions. Moreover, HS from the left and the right heart fields exhibit differential cleavage by heparanase, an endo-beta-d- glucuronidase that cleaves specific sequences within the HS chain. In embryo culture, microinjection of the active human heparanase enzyme into the right but not the left pericardial cavity at stage 7-8+ resulted in reversed heart looping in a dose-dependent manner. Heart reversal following microinjection of heparin or heparin derivatives suggests the involvement of N- and 6-O-sulfation but not 2-O-sulfation in the heart looping process.

Animals↗

PubMed2004

Mapping critical biological motifs and biosynthetic pathways of heparan sulfate.

Heparan sulfate (HS) interacts with numerous proteins at the cell surface and orchestrates myriad biological events. Unraveling the mechanisms of these events at the molecular level calls for the structural analysis of these negatively charged and highly heterogeneous biopolymers. However, HS is often available only in small quantities, and the task of structural analysis necessitates the use of ultra-sensitive methods, such as mass spectrometry. Sequence heterogeneity within HS chains required us to identify critical functional groups and their spacing to determine structure-function relationships for HS. We carried out structural analysis of HS isolated from wild type, 3-OST-1, 3-OST-3A, or 3-OST-5 sulfotransferase-transduced Chinese hamster ovary cells and also from various tissues. In the context of tissue-specific HS, the data allowed us to map the biosynthetic pathways responsible for the placement of critical groups. As a means of determining the distance between critical groups within a motif, we determined the spacing of the rare GlcNAc-GlcA disaccharide sequence in the completely desulfated re-N-sulfated porcine intestinal heparin. These disaccharides are biosynthetic regulatory markers for 3-OST-1 modification and the partial structure of the antithrombin III binding site. They occur only at the distance of hexasaccharide, octasaccharide, decasaccharide, or dodecasaccharide. Thus this approach allowed us to map both the biosynthetic pathways for generating critical functional groups and their spacing within HS. Our new strategy removes two obstacles to rapid progress in this field of research.

Animals↗

PubMed2004

Effect of thrombopoietin alone and a combination of cytochalasin B and ethylene glycol bis(beta-aminoethyl ether) N,N'-tetraacetic acid-AM on the survival and function of autologous baboon platelets stored at 4 degrees C for as long as 5 days.

BACKGROUND: PLTs stored at 22 degrees C have the potential for bacterial contamination, a problem that could be reduced by 4 degrees C storage. Nevertheless, PLTs stored at 4 degrees C exhibit a significantly reduced life span. This study was performed to determine whether treatment of PLTs with thrombopoietin or cytochalasin B plus ethylene glycol bis(beta-aminoethyl ether) N,N'-tetraacetic acid (EGTA)-AM could prevent exponential loss of PLTs stored at 4 degrees C. STUDY DESIGN AND METHODS: Autologous baboon PLTs were stored at 22 or 4 degrees C. The 4 degrees C stored PLTs were treated with 1.5 ng per mL thrombopoietin, with 1 micro mol per L cytochalasin B, and 80 micromol per L EGTA-AM (cyto-EGTA) or not treated and labeled with (111)In-oxine to study their in vivo recovery and life span. PLT function was assessed by correction of an aspirin-induced prolonged bleeding time. Aggregation responses and morphology were also assessed. RESULTS: PLTs stored at 22 degrees C had normal in vivo recovery and linear survival. PLTs stored at 4 degrees C, whether or not they were treated with thrombopoietin, had normal recovery and exponential survival. Aggregation of cyto-EGTA-treated PLTs was similar for PLTs stored at 4 degrees C and fresh PLTs, but decreased in PLTs stored at 22 degrees C for 5 days. The addition of cyto-EGTA to PLTs before 4 degrees C storage inhibited morphologic changes that occurred in PLTs stored at 22 degrees C and cold-induced PLT clumping, but did not prevent exponential disappearance of the PLTs. CONCLUSION: Addition of thrombopoietin or cyto-chalasin B and EGTA-AM to PLTs before 4 degrees C storage did not prevent exponential loss of PLTs.

Animals↗

PubMed2003

Light-induced 3-O-sulfotransferase expression alters pineal heparan sulfate fine structure. A surprising link to circadian rhythm.

Proteoglycans are dominant glycoconjugates located on the cell surface and in extracellular spaces and consist of a core protein with one or more glycosaminoglycan side chains linked covalently. Heparan sulfate (HS) belongs to the family of glycosaminoglycans. HS has been assigned a variety of physiological and pathological functions, such as cell-cell adhesion, cell-matrix adhesion, cell proliferation, motility and differentiation, lipoprotein metabolism, blood coagulation, inflammation, tissue regeneration, tumor progression and invasion, pathogenic infection by bacteria, protozoa, and viruses, through specific interaction with a wide array of proteins, ligands, receptors, and pathogens (Bernfield, M., Gotte, M., Park, P. W., Reizes, O., Fitzgerald, M. L., Lincecum, J., and Zako, M. (1999) Annu. Rev. Biochem. 68, 729-777). We have shown here for the first time that light induces changes in pineal HS fine structure and that occurrence of the rare 3-O sulfation catalyzed by HS 3-O-sulfotransferase (3-OST2) is predominantly restricted to daytime pineal glands.

Animals↗

PubMed2003

Determining heparan sulfate structure in the vicinity of specific sulfotransferase recognition sites by mass spectrometry.

Sulfated motifs on heparan sulfate (HS) are involved in various extracellular processes from cell signaling to enzymatic regulation, but the structures of these motifs are obscure. We have developed a strategy to determine the structure of sulfotransferase recognition sites which constitute these motifs. Stable isotope is first introduced into specific sites on HS with HS sulfotransferases and the modified HS is then digested into oligosaccharides of differing sizes. The overlapping oligosaccharides containing the introduced stable isotope are identified by changes in the m/z profiles by mass spectrometry, and their relationships are elucidated. In this way, the HS structures in the vicinity of the sulfotransferase recognition site are quickly determined and groups on precursor structures of HS that direct the action of HS sulfotransferases are pinpointed.

Animals↗

PubMed2003

Rapid two-step synthesis of mitrin from heparosan: a replacement for heparin.

We have engineered a two-step enzymatic synthesis of Mitrin which is a more potent and homogeneous anticoagulant than the current animal-derived heparin. This engineered heparin may have advantages of being free from animal-derived pathogens and may also have reduced side effects such as heparin induced thrombocytopenia. This approach can also be extended to tailor heparin-based drugs with improved therapeutic characteristics to treat other disorders or infections in which heparin-like molecules play a major role.

Anticoagulants↗

PubMed2003

Enzymatic synthesis of antithrombin III-binding heparan sulfate pentasaccharide.

Heparan sulfate (HS) proteoglycans are crucial to numerous biological processes and pathological conditions, but to date only a few HS structures have been synthesized and characterized with regard to structure-function relationships. Because HS proteoglycans are highly diverse in structure, there are substantial limitations on their synthesis by classical chemical means, and thus new methods to rapidly assemble bioactive HS structures are needed. Here we report the biosynthesis of bioactive HS oligosaccharides using an engineered set of cloned enzymes that mimics the Golgi apparatus in vitro. We rapidly and efficiently assembled the antithrombin III-binding pentasaccharide in just 6 steps, in contrast to the approximately 60 steps needed for its chemical synthesis, with an overall yield at least twofold greater and a completion time at least 100 times faster than for the chemical process.

Antithrombin III↗

PubMed2003

Chemoenzymatic synthesis of classical and non-classical anticoagulant heparan sulfate polysaccharides.

Heparan sulfate (HS) polysaccharides interact with numerous proteins at the cell surface and orchestrate many different biological functions. Though many functions of HS are well established, only a few specific structures can be attributed to HS functions. The extreme diversity of HS makes chemical synthesis of specific bioactive HS structures a cumbersome and tedious undertaking that requires laborious and careful functional group manipulations. Now that many of the enzymes involved in HS biosynthesis are characterized, we show in this study how one can rapidly and easily assemble bioactive HS structures with a set of cloned enzymes. We have demonstrated the feasibility of this new approach to rapidly assemble antithrombin III-binding classical and non-classical anticoagulant polysaccharide structures for the first time.

Antithrombin III↗

PubMed2003

Ets motifs are necessary for endothelial cell-specific expression of a 723-bp Tie-2 promoter/enhancer in Hprt targeted transgenic mice.

OBJECTIVE: Tie-2 is an endothelial cell-specific receptor tyrosine kinase that is involved in the remodeling of blood vessels and angiogenesis. Our goal was to characterize Tie-2 promoter function as a means of providing insight into the mechanisms of endothelial cell-specific gene regulation. METHODS AND RESULTS: When targeted to the Hprt locus of mice, a small Tie-2 promoter fragment (containing a 300-bp intronic enhancer coupled upstream to a 423-bp core promoter) (T-short) directed widespread endothelial cell expression in vivo. The T-short promoter contains 2 clusters of Ets sites, one in the first exon, the other in the intronic enhancer. In cultured endothelial cells, a combined mutation of the Ets motifs resulted in a significant reduction in promoter activity. Consistent with these results, the same Ets mutations resulted in a loss of detectable expression of the T-short promoter in all vascular beds with the notable exception of the brain. CONCLUSIONS: These results suggest that the T-short promoter contains information for widespread expression in the vascular tree, Ets sites are necessary for in vivo promoter activity, and the shorter Tie-2 fragment may be useful as a tool to direct heterologous gene expression within the intact endothelium.

Amino Acid Motifs↗

PubMed2003

Coagulation activation and long-term outcome in acute coronary syndromes.

After an episode of unstable angina or myocardial infarction, a high proportion of patients show biochemical signs of coagulation activation, expressed as persistently elevated thrombin generation, in their blood. It is not known whether this has any influence on long-term outcome. In this prospective multicenter cohort study, we assessed the relation of persistently elevated thrombin generation to outcome in 319 consecutive patients with acute coronary syndromes enrolled in the Global Use of Strategies To Open occluded coronary arteries (GUSTO) IIb trial. Plasma prothrombin fragment 1 + 2 levels, an index of "in vivo" thrombin generation, was measured during the acute phase and after 1, 6, and 12 months, and its relation to outcome was assessed during a median 29-month follow-up period. The primary end point of cardiac death or myocardial (re)infarction occurred in 61 patients (19%). There was a U-shaped relationship between plasma prothrombin fragment 1 + 2 levels and the risk of developing the primary end point; intermediate levels (1.5-1.9 nM) were associated with the lowest risk, whereas both higher (> 1.9 nM) and lower (< 1.5 nM) values were associated with an increased risk (relative risk [RR] 1.56 and 95% confidence interval [CI], 1.25-2.28; RR, 1.35 and 95% CI, 1.11-1.86, respectively). After an episode of acute coronary syndrome, both high and low levels of thrombin generation are predictors of an increased risk of an unfavorable outcome.

Aged↗

PubMed2003

The involvement of heparan sulfate (HS) in FGF1/HS/FGFR1 signaling complex.

Fibroblast growth factor (FGF) signaling begins with the formation of a ternary complex of FGF, FGF receptor (FGFR), and heparan sulfate (HS). Multiple models have been proposed for the ternary complex. However, major discrepancies exist among those models, and none of these models have evaluated the functional importance of the interacting regions on the HS chains. To resolve the discrepancies, we measured the size and molar ratio of HS in the complex and showed that both FGF1 and FGFR1 simultaneously interact with HS; therefore, a model of 2:2:2 FGF1.HS.FGFR1 was shown to fit the data. Using genetic and biochemical methods, we generated HSs that were defective in FGF1 and/or FGFR1 binding but could form the signaling ternary complex. Both genetically and chemically modified HSs were subsequently assessed in a BaF3 cell mitogenic activity assay. The ability of HS to support the ternary complex formation was found to be required for FGF1-stimulated cell proliferation. Our data also proved that specific critical groups and sites on HS support complex formation. Furthermore, the molar ratio of HS, FGF1, and FGFR1 in the ternary complex was found to be independent of the size of HS, which indicates that the selected model can take place on the cell surface proteoglycans. Finally, a mechanism for the FGF.FGFR signaling complex formation on cell membrane was proposed, where FGF and FGFR have their own binding sites on HS and a distinct ternary complex formation site is directly responsible for mitogenic activity.

Cell Line↗