Browsing by Subject "Glycoproteins"

Now showing 1 - 10 of 15
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    Clinically relevant variants identified in thoracic aortic aneurysm patients by research exome sequencing
    (Wiley Blackwell (John Wiley & Sons), 2016-05) Schubert, Jeffrey A.; Landis, Benjamin J.; Shikany, Amy R.; Hinton, Robert B.; Ware, Stephanie M.; Department of Pediatrics, IU School of Medicine
    Thoracic aortic aneurysm (TAA) is a genetically heterogeneous disease involving subclinical and progressive dilation of the thoracic aorta, which can lead to life-threatening complications such as dissection or rupture. Genetic testing is important for risk stratification and identification of at risk family members, and clinically available genetic testing panels have been expanding rapidly. However, when past testing results are normal, there is little evidence to guide decision-making about the indications and timing to pursue additional clinical genetic testing. Results from research based genetic testing can help inform this process. Here we present 10 TAA patients who have a family history of disease and who enrolled in research-based exome testing. Nine of these ten patients had previous clinical genetic testing that did not identify the cause of disease. We sought to determine the number of rare variants in 23 known TAA associated genes identified by research-based exome testing. In total, we found 10 rare variants in six patients. Likely pathogenic variants included a TGFB2 variant in one patient and a SMAD3 variant in another. These variants have been reported previously in individuals with similar phenotypes. Variants of uncertain significance of particular interest included novel variants in MYLK and MFAP5, which were identified in a third patient. In total, clinically reportable rare variants were found in 6/10 (60%) patients, with at least 2/10 (20%) patients having likely pathogenic variants identified. These data indicate that consideration of re-testing is important in TAA patients with previous negative or inconclusive results.
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    Control of Bone Anabolism in Response to Mechanical Loading and PTH by Distinct Mechanisms Downstream of the PTH Receptor
    (Wiley, 2017-03) Delgado-Calle, Jesus; Tu, Xiaolin; Pacheco-Costa, Rafael; McAndrews, Kevin; Edwards, Rachel; Pellegrini, Gretel G.; Kuhlenschmidt, Kali; Olivos, Naomie; Robling, Alexander; Peacock, Munro; Plotkin, Lilian I.; Bellido, Teresita; Anatomy, Cell Biology and Physiology, School of Medicine
    Osteocytes integrate the responses of bone to mechanical and hormonal stimuli by poorly understood mechanisms. We report here that mice with conditional deletion of the parathyroid hormone (PTH) receptor 1 (Pth1r) in dentin matrix protein 1 (DMP1)-8kb-expressing cells (cKO) exhibit a modest decrease in bone resorption leading to a mild increase in cancellous bone without changes in cortical bone. However, bone resorption in response to endogenous chronic elevation of PTH in growing or adult cKO mice induced by a low calcium diet remained intact, because the increased bone remodeling and bone loss was indistinguishable from that exhibited by control littermates. In contrast, the bone gain and increased bone formation in cancellous and cortical bone induced by daily injections of PTH and the periosteal bone apposition induced by axial ulna loading were markedly reduced in cKO mice compared to controls. Remarkably, however, wild-type (WT) control littermates and transgenic mice overexpressing SOST injected daily with PTH exhibit similar activation of Wnt/β-catenin signaling, increased bone formation, and cancellous and cortical bone gain. Taken together, these findings demonstrate that Pth1r in DMP1-8kb-expressing cells is required to maintain basal levels of bone resorption but is dispensable for the catabolic action of chronic PTH elevation; and it is essential for the anabolic actions of daily PTH injections and mechanical loading. However, downregulation of Sost/sclerostin, previously shown to be required for bone anabolism induced by mechanical loading, is not required for PTH-induced bone gain, showing that other mechanisms downstream of the Pth1r in DMP1-8kb-expressing cells are responsible for the hormonal effect.
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    F-Actin regulation of SNARE-mediated insulin secretion
    (2013-10-07) Kalwat, Michael Andrew; Thurmond, Debbie C.; Atkinson, Simon; Hudmon, Andy; Mirmira, Raghavendra G.
    In response to glucose, pancreatic islet beta cells secrete insulin in a biphasic manner, and both phases are diminished in type 2 diabetes. In beta cells, cortical F-actin beneath the plasma membrane (PM) prevents insulin granule access to the PM and glucose stimulates remodeling of this cortical F-actin to allow trafficking of insulin granules to the PM. Glucose stimulation activates the small GTPase Cdc42, which then activates p21-activated kinase 1 (PAK1); both Cdc42 and PAK1 are required for insulin secretion. In conjunction with Cdc42-PAK1 signaling, the SNARE protein Syntaxin 4 dissociates from F-actin to allow SNARE complex formation and insulin exocytosis. My central hypothesis is that, in the pancreatic beta cell, glucose signals through a Cdc42-PAK1-mediated pathway to remodel the F-actin cytoskeleton to mobilize insulin granules to SNARE docking sites at the PM to evoke glucose stimulated second phase insulin secretion. To investigate this, PAK1 was inhibited in MIN6 beta cells with IPA3 followed by live-cell imaging of F-actin remodeling using the F-actin probe, Lifeact-GFP. PAK1 inhibition prevented normal glucose-induced F-actin remodeling. PAK1 inhibition also prevented insulin granule accumulation at the PM in response to glucose. The ERK pathway was implicated, as glucose-stimulated ERK activation was decreased under PAK1-depleted conditions. Further study showed that inhibition of ERK impaired insulin secretion and cortical F-actin remodeling. One of the final steps of insulin secretion is the fusion of insulin granules with the PM which is facilitated by the SNARE proteins Syntaxin 4 on the PM and VAMP2 on the insulin granule. PAK1 activation was also found to be critical for Syntaxin 4-F-actin complex dynamics in beta cells, linking the Cdc42-PAK1 signaling pathway to SNARE-mediated exocytosis. Syntaxin 4 interacts with the F-actin severing protein Gelsolin, and in response to glucose Gelsolin dissociates from Syntaxin 4 in a calcium-dependent manner to allow Syntaxin 4 activation. Disrupting the interaction between Syntaxin 4 and Gelsolin aberrantly activates endogenous Syntaxin 4, elevating basal insulin secretion. Taken together, these results illustrate that signaling to F-actin remodeling is important for insulin secretion and that F-actin and its binding proteins can impact the final steps of insulin secretion.
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    Quantitative Serum Glycomics of Esophageal Adenocarcinoma, and Other Esophageal Disease Onsets
    (American Chemical Society, 2009-06) Mechref, Yehia; Hussein, Ahmed; Bekesova, Slavka; Pungpapong, Vitara; Zhang, Min; Dobrolecki, Lacey E.; Hickey, Robert J.; Hammoud, Zane T.; Novotny, Milos V.; Department of Medicine, IU School of Medicine
    Aberrant glycosylation has been implicated in various types of cancers and changes in glycosylation may be associated with signaling pathways during malignant transformation. Glycomic profiling of blood serum, in which cancer cell proteins or their fragments with altered glycosylation patterns are shed, could reveal the altered glycosylation. We performed glycomic profiling of serum from patients with no known disease (N=18), patients with high grade dysplasia (HGD, N=11) and Barrett’s (N=5), and patients with esophageal adenocarcinoma (EAC, N=50) in an attempt to delineate distinct differences in glycosylation between these groups. The relative intensities of 98 features were significantly different among the disease onsets; 26 of these correspond to known glycan structures. The changes in the relative intensities of three of the known glycan structures predicted esophageal adenocarcinoma with 94% sensitivity and better than 60% specificity as determined by receiver operating characteristic (ROC) analysis. We have demonstrated that comparative glycomic profiling of EAC reveals a subset of glycans that can be selected as candidate biomarkers. These markers can differentiate disease-free from HGD, disease-free from EAC, and HGD from EAC. The clinical utility of these glycan biomarkers requires further validation.
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    Sclerostin Inhibition Reverses Skeletal Fragility in an Lrp5-Deficient Mouse Model of OPPG Syndrome
    (American Association for the Advancement of Science, 2013) Kedlaya, Rajendra; Veera, Shreya; Horan, Daniel J.; Moss, Rachel E.; Ayturk, Ugur M.; Jacobsen, Christina M.; Bowen, Margot E.; Paszty, Chris; Warman, Matthew L.; Robling, Alexander G.; Anatomy, Cell Biology and Physiology, School of Medicine
    Osteoporosis pseudoglioma syndrome (OPPG) is a rare genetic disease that produces debilitating effects in the skeleton. OPPG is caused by mutations in LRP5, a WNT co-receptor that mediates osteoblast activity. WNT signaling through LRP5, and also through the closely related receptor LRP6, is inhibited by the protein sclerostin (SOST). It is unclear whether OPPG patients might benefit from the anabolic action of sclerostin neutralization therapy (an approach currently being pursued in clinical trials for postmenopausal osteoporosis) in light of their LRP5 deficiency and consequent osteoblast impairment. To assess whether loss of sclerostin is anabolic in OPPG, we measured bone properties in a mouse model of OPPG (Lrp5(-/-)), a mouse model of sclerosteosis (Sost(-/-)), and in mice with both genes knocked out (Lrp5(-/-);Sost(-/-)). Lrp5(-/-);Sost(-/-) mice have larger, denser, and stronger bones than do Lrp5(-/-) mice, indicating that SOST deficiency can improve bone properties via pathways that do not require LRP5. Next, we determined whether the anabolic effects of sclerostin depletion in Lrp5(-/-) mice are retained in adult mice by treating 17-week-old Lrp5(-/-) mice with a sclerostin antibody for 3 weeks. Lrp5(+/+) and Lrp5(-/-) mice each exhibited osteoanabolic responses to antibody therapy, as indicated by increased bone mineral density, content, and formation rates. Collectively, our data show that inhibiting sclerostin can improve bone mass whether LRP5 is present or not. In the absence of LRP5, the anabolic effects of SOST depletion can occur via other receptors (such as LRP4/6). Regardless of the mechanism, our results suggest that humans with OPPG might benefit from sclerostin neutralization therapies.
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    Stat3 Downstream Gene Product Chitinase 3-Like 1 Is a Potential Biomarker of Inflammation-induced Lung Cancer in Multiple Mouse Lung Tumor Models and Humans
    (Public Library of Science, 2013-04-22) Yan, Cong; Ding, Xinchun; Wu, Lingyan; Yu, Menggang; Qu, Peng; Du, Hong; Pathology and Laboratory Medicine, School of Medicine
    Over-activation of the signal transducers and activators of the transcription 3 (Stat3) pathway in lung alveolar type II (AT II) epithelial cells induces chronic inflammation and adenocarcinoma in the lung of CCSP-rtTA/(tetO)7-CMV-Stat3C bitransgenic mice. One of Stat3 downstream genes products, chitinase 3-like 1 (CHI3L1) protein, showed increased concentration in both bronchioalveolar lavage fluid (BALF) and blood of doxycycline-treated CCSP-rtTA/(tetO)7-CMV-Stat3C bitransgenic mice. When tested in other inflammation-induced lung cancer mouse models, the CHI3L1 protein concentration was also highly increased in BALF and blood of these models with tumors. Immunohistochemical staining showed strong staining of CHI3L1 protein around tumor areas in these mouse models. Analysis of normal objects and lung cancer patients revealed a significant elevation of CHI3L1 protein concentration in human serum samples from all categories of lung cancers. Furthermore, recombinant CHI3L protein stimulated proliferation and growth of Lewis lung cancer cells. Therefore, secretory CHI3L1 plays an important role in inflammation-induced lung cancer formation and potentially serve as a biomarker for lung cancer prediction. Based on our previous publication and this work, this is the first animal study linking overexpression of CHI3L1 to various lung tumor mouse models. These models will facilitate identification of additional biomarkers to predict and verify lung cancer under various pathogenic conditions, which normally cannot be done in humans.