Browsing by Author "Yong, Jing"

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    Biosynthesis, structure, and folding of the insulin precursor protein
    (Wiley, 2018-09) Liu, Ming; Weiss, Michael A.; Arunagiri, Anoop; Yong, Jing; Rege, Nischay; Sun, Jinhong; Haataja, Leena; Kaufman, Randal J.; Arvan, Peter; Biochemistry and Molecular Biology, School of Medicine
    Insulin synthesis in pancreatic β-cells is initiated as preproinsulin. Prevailing glucose concentrations, which oscillate pre- and postprandially, exert major dynamic variation in preproinsulin biosynthesis. Accompanying upregulated translation of the insulin precursor includes elements of the endoplasmic reticulum (ER) translocation apparatus linked to successful orientation of the signal peptide, translocation and signal peptide cleavage of preproinsulin-all of which are necessary to initiate the pathway of proper proinsulin folding. Evolutionary pressures on the primary structure of proinsulin itself have preserved the efficiency of folding ("foldability"), and remarkably, these evolutionary pressures are distinct from those protecting the ultimate biological activity of insulin. Proinsulin foldability is manifest in the ER, in which the local environment is designed to assist in the overall load of proinsulin folding and to favour its disulphide bond formation (while limiting misfolding), all of which is closely tuned to ER stress response pathways that have complex (beneficial, as well as potentially damaging) effects on pancreatic β-cells. Proinsulin misfolding may occur as a consequence of exuberant proinsulin biosynthetic load in the ER, proinsulin coding sequence mutations, or genetic predispositions that lead to an altered ER folding environment. Proinsulin misfolding is a phenotype that is very much linked to deficient insulin production and diabetes, as is seen in a variety of contexts: rodent models bearing proinsulin-misfolding mutants, human patients with Mutant INS-gene-induced Diabetes of Youth (MIDY), animal models and human patients bearing mutations in critical ER resident proteins, and, quite possibly, in more common variety type 2 diabetes.
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    Ectopic clotting factor VIII expression and misfolding in hepatocytes as a cause for hepatocellular carcinoma
    (Elsevier, 2022-12-07) Kapelanski-Lamoureux, Audrey; Chen, Zhouji; Gao, Zu-Hua; Deng, Ruishu; Lazaris, Anthoula; Lebeaupin, Cynthia; Giles, Lisa; Malhotra, Jyoti; Yong, Jing; Zou, Chenhui; de Jong, Ype P.; Metrakos, Peter; Herzog, Roland W.; Kaufman, Randal J.; Pediatrics, School of Medicine
    Hemophilia A gene therapy targets hepatocytes to express B domain deleted (BDD) clotting factor VIII (FVIII) to permit viral encapsidation. Since BDD is prone to misfolding in the endoplasmic reticulum (ER) and ER protein misfolding in hepatocytes followed by high-fat diet (HFD) can cause hepatocellular carcinoma (HCC), we studied how FVIII misfolding impacts HCC development using hepatocyte DNA delivery to express three proteins from the same parental vector: (1) well-folded cytosolic dihydrofolate reductase (DHFR); (2) BDD-FVIII, which is prone to misfolding in the ER; and (3) N6-FVIII, which folds more efficiently than BDD-FVIII. One week after DNA delivery, when FVIII expression was undetectable, mice were fed HFD for 65 weeks. Remarkably, all mice that received BDD-FVIII vector developed liver tumors, whereas only 58% of mice that received N6 and no mice that received DHFR vector developed liver tumors, suggesting that the degree of protein misfolding in the ER increases predisposition to HCC in the context of an HFD and in the absence of viral transduction. Our findings raise concerns of ectopic BDD-FVIII expression in hepatocytes in the clinic, which poses risks independent of viral vector integration. Limited expression per hepatocyte and/or use of proteins that avoid misfolding may enhance safety.
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    Integrated Physiology of the Exocrine and Endocrine Compartments in Pancreatic Diseases: Workshop Proceedings
    (Wolters Kluwer, 2022) Mastracci, Teresa L.; Apte, Minoti; Amundadottir, Laufey T.; Alvarsson, Alexandra; Artandi, Steven; Bellin, Melena D.; Bernal-Mizrachi, Ernesto; Caicedo, Alejandro; Campbell-Thompson, Martha; Cruz-Monserrate, Zobeida; El Ouaamari, Abdelfattah; Gaulton, Kyle J.; Geisz, Andrea; Goodarzi, Mark O.; Hara, Manami; Hull-Meichle, Rebecca L.; Kleger, Alexander; Klein, Alison P.; Kopp, Janel L.; Kulkarni, Rohit N.; Muzumdar, Mandar D.; Naren, Anjaparavanda P.; Oakes, Scott A.; Olesen, Søren S.; Phelps, Edward A.; Powers, Alvin C.; Stabler, Cherie L.; Tirkes, Temel; Whitcomb, David C.; Yadav, Dhiraj; Yong, Jing; Zaghloul, Norann A.; Sander, Maike; Pandol, Stephen J.; Biology, School of Science
    The Integrated Physiology of the Exocrine and Endocrine Compartments in Pancreatic Diseases Workshop was a 1.5-day scientific conference at the National Institutes of Health (Bethesda, MD) that engaged clinical and basic science investigators interested in diseases of the pancreas. This report summarizes the workshop proceedings. The goal of the workshop was to forge connections and identify gaps in knowledge that could guide future research directions. Presentations were segregated into six major themes, including: (a) Pancreas Anatomy and Physiology; (b) Diabetes in the Setting of Exocrine Disease; (c) Metabolic Influences on the Exocrine Pancreas; (d) Genetic Drivers of Pancreatic Diseases; (e) Tools for Integrated Pancreatic Analysis; and (f) Implications of Exocrine-Endocrine Crosstalk. For each theme, there were multiple presentations followed by panel discussions on specific topics relevant to each area of research; these are summarized herein. Significantly, the discussions resulted in the identification of research gaps and opportunities for the field to address. In general, it was concluded that as a pancreas research community, we must more thoughtfully integrate our current knowledge of the normal physiology as well as the disease mechanisms that underlie endocrine and exocrine disorders so that there is a better understanding of the interplay between these compartments.