Browsing by Subject "Proteolysis"

Now showing 1 - 5 of 5
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    Association of cerebrospinal fluid Aβ42 with A2M gene in cognitively normal subjects
    (Elsevier, 2014-02) Millard, Steven P.; Lutz, Franziska; Li, Ge; Galasko, Douglas R.; Farlow, Martin R.; Quinn, Joseph F.; Kaye, Jeffrey A.; Leverenz, James B.; Tsuang, Debby; Yu, Chang-En; Peskind, Elaine R.; Bekris, Lynn M.; Department of Neurology, IU School of Medicine
    Low cerebrospinal fluid (CSF) Aβ42 levels correlate with increased brain Aβ deposition in Alzheimer’s disease (AD), which suggests a disruption in the degradation and clearance of Aβ from the brain. In addition, APOE ε4 carriers have lower CSF Aβ42 levels than non-carriers. The hypothesis of this investigation was that CSF Aβ42 levels correlate with regulatory region variation in genes that are biologically associated with degradation or clearance of Aβ from the brain. CSF Aβ42 levels were tested for associations with Aβ degradation and clearance genes and APOE ε4. Twenty-four SNPs located within the 5′ and 3′ regions of 12 genes were analyzed. The study sample consisted of 99 AD patients and 168 cognitively normal control subjects. CSF Aβ42 levels were associated with APOE ε4 status in controls but not in AD patients
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    Autophagy is a gatekeeper of hepatic differentiation and carcinogenesis by controlling the degradation of Yap
    (Nature Research, 2018-11-23) Lee, Youngmin A.; Noon, Luke A.; Akat, Kemal M.; Ybanez, Maria D.; Lee, Ting-Fang; Berres, Marie-Luise; Fujiwara, Naoto; Goossens, Nicolas; Chou, Hsin-I; Parvin-Nejad, Fatemeh P.; Khambu, Bilon; Kramer, Elisabeth G.M.; Gordon, Ronald; Pfleger, Cathie; Germain, Doris; John, Gareth R.; Campbell, Kirk N.; Yue, Zhenyu; Yin, Xiao-Ming; Cuervo, Ana Maria; Czaja, Mark J.; Fiel, M. Isabel; Hoshida, Yujin; Friedman, Scott L.; Pathology and Laboratory Medicine, School of Medicine
    Activation of the Hippo pathway effector Yap underlies many liver cancers, however no germline or somatic mutations have been identified. Autophagy maintains essential metabolic functions of the liver, and autophagy-deficient murine models develop benign adenomas and hepatomegaly, which have been attributed to activation of the p62/Sqstm1-Nrf2 axis. Here, we show that Yap is an autophagy substrate and mediator of tissue remodeling and hepatocarcinogenesis independent of the p62/Sqstm1-Nrf2 axis. Hepatocyte-specific deletion of Atg7 promotes liver size, fibrosis, progenitor cell expansion, and hepatocarcinogenesis, which is rescued by concurrent deletion of Yap. Our results shed new light on mechanisms of Yap degradation and the sequence of events that follow disruption of autophagy, which is impaired in chronic liver disease.
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    Global protease activity profiling provides differential diagnosis of pancreatic cysts
    (American Association for Cancer Research, 2017-08-15) Ivry, Sam L.; Sharib, Jeremy M.; Dominguez, Dana A.; Roy, Nilotpal; Hatcher, Stacy E.; Yip-Schneider, Michele T.; Schmidt, C. Max; Brand, Randall E.; Park, Walter G.; Hebrok, Matthias; Kim, Grace E.; O'Donoghue, Anthony J.; Kirkwood, Kimberly S.; Craik, Charles S.; Surgery, School of Medicine
    Purpose: Pancreatic cysts are estimated to be present in 2%-3% of the adult population. Unfortunately, current diagnostics do not accurately distinguish benign cysts from those that can progress into invasive cancer. Misregulated pericellular proteolysis is a hallmark of malignancy, and therefore, we used a global approach to discover protease activities that differentiate benign nonmucinous cysts from premalignant mucinous cysts.Experimental Design: We employed an unbiased and global protease profiling approach to discover protease activities in 23 cyst fluid samples. The distinguishing activities of select proteases was confirmed in 110 samples using specific fluorogenic substrates and required less than 5 μL of cyst fluid.Results: We determined that the activities of the aspartyl proteases gastricsin and cathepsin E are highly increased in fluid from mucinous cysts. IHC analysis revealed that gastricsin expression was associated with regions of low-grade dysplasia, whereas cathepsin E expression was independent of dysplasia grade. Gastricsin activity differentiated mucinous from nonmucinous cysts with a specificity of 100% and a sensitivity of 93%, whereas cathepsin E activity was 92% specific and 70% sensitive. Gastricsin significantly outperformed the most widely used molecular biomarker, carcinoembryonic antigen (CEA), which demonstrated 94% specificity and 65% sensitivity. Combined analysis of gastricsin and CEA resulted in a near perfect classifier with 100% specificity and 98% sensitivity.Conclusions: Quantitation of gastricsin and cathepsin E activities accurately distinguished mucinous from nonmucinous pancreatic cysts and has the potential to replace current diagnostics for analysis of these highly prevalent lesions. Clin Cancer Res; 23(16); 4865-74. ©2017 AACR.
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    Pathways of Antigen Processing
    (Annual Reviews, 2013) Blum, Janice S.; Wearsch, Pamela A.; Cresswell, Peter; Microbiology and Immunology, School of Medicine
    T cell recognition of antigen-presenting cells depends on their expression of a spectrum of peptides bound to major histocompatibility complex class I (MHC-I) and class II (MHC-II) molecules. Conversion of antigens from pathogens or transformed cells into MHC-I- and MHC-II-bound peptides is critical for mounting protective T cell responses, and similar processing of self proteins is necessary to establish and maintain tolerance. Cells use a variety of mechanisms to acquire protein antigens, from translation in the cytosol to variations on the theme of endocytosis, and to degrade them once acquired. In this review, we highlight the aspects of MHC-I and MHC-II biosynthesis and assembly that have evolved to intersect these pathways and sample the peptides that are produced.
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    Protein Kinase A Is a Master Regulator of Physiological and Pathological Cardiac Hypertrophy
    (American Heart Association, 2024) Bai, Yingyu; Zhang, Xiaoying; Li, Ying; Qi, Fei; Liu, Chong; Ai, Xiaojie; Tang, Mingxin; Szeto, Christopher; Gao, Erhe; Hua, Xiang; Xie, Mingxing; Wang, Xuejun; Tian, Ying; Chen, Yongjie; Huang, Guowei; Zhang, Junping; Xiao, Weidong; Zhang, Lili; Liu, Xueyuan; Yang, Qing; Houser, Steven R.; Chen, Xiongwen; Pediatrics, School of Medicine
    Background: The sympathoadrenergic system and its major effector PKA (protein kinase A) are activated to maintain cardiac output coping with physiological or pathological stressors. If and how PKA plays a role in physiological cardiac hypertrophy (PhCH) and pathological CH (PaCH) are not clear. Methods: Transgenic mouse models expressing the PKA inhibition domain (PKAi) of PKA inhibition peptide alpha (PKIalpha)-green fluorescence protein (GFP) fusion protein (PKAi-GFP) in a cardiac-specific and inducible manner (cPKAi) were used to determine the roles of PKA in physiological CH during postnatal growth or induced by swimming, and in PaCH induced by transaortic constriction (TAC) or augmented Ca2+ influx. Kinase profiling was used to determine cPKAi specificity. Echocardiography was used to determine cardiac morphology and function. Western blotting and immunostaining were used to measure protein abundance and phosphorylation. Protein synthesis was assessed by puromycin incorporation and protein degradation by measuring protein ubiquitination and proteasome activity. Neonatal rat cardiomyocytes (NRCMs) infected with AdGFP (GFP adenovirus) or AdPKAi-GFP (PKAi-GFP adenovirus) were used to determine the effects and mechanisms of cPKAi on myocyte hypertrophy. rAAV9.PKAi-GFP was used to treat TAC mice. Results: (1) cPKAi delayed postnatal cardiac growth and blunted exercise-induced PhCH; (2) PKA was activated in hearts after TAC due to activated sympathoadrenergic system, the loss of endogenous PKIα (PKA inhibition peptide α), and the stimulation by noncanonical PKA activators; (3) cPKAi ameliorated PaCH induced by TAC and increased Ca2+ influxes and blunted neonatal rat cardiomyocyte hypertrophy by isoproterenol and phenylephrine; (4) cPKAi prevented TAC-induced protein synthesis by inhibiting mTOR (mammalian target of rapamycin) signaling through reducing Akt (protein kinase B) activity, but enhancing inhibitory GSK-3α (glycogen synthase kinase-3α) and GSK-3β signals; (5) cPKAi reduced protein degradation by the ubiquitin-proteasome system via decreasing RPN6 phosphorylation; (6) cPKAi increased the expression of antihypertrophic atrial natriuretic peptide (ANP); (7) cPKAi ameliorated established PaCH and improved animal survival. Conclusions: Cardiomyocyte PKA is a master regulator of PhCH and PaCH through regulating protein synthesis and degradation. cPKAi can be a novel approach to treat PaCH.