Federica Raggi1, Anna Livia Pissavino1, Roberta Resaz1, Daniela Segalerba1, Andrea Puglisi1, Cristina Vanni1, Francesca Antonini2, Genny Del Zotto2, Alessandra Gamberucci3, Paola Marcolongo3, Maria Carla Bosco1, Federica Grillo4,5, Luca Mastracci4,5, Alessandra Eva6. 1. Laboratory of Molecular Biology, Department of Translational Research, Laboratory Medicine, Diagnosis and Services, Istituto Giannina Gaslini, Largo Gaslini 5, 16147, Genoa, Italy. 2. Core Facilities Laboratory, Department of Translational Research, Laboratory Medicine, Diagnosis and Services, Istituto Giannina Gaslini, Genoa, Italy. 3. Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy. 4. Pathology Unit, Department of Surgical Sciences and Integrated Diagnostics, University of Genova, Genoa, Italy. 5. IRCCS AOU San Martino IST Genova, Genoa, Italy. 6. Laboratory of Molecular Biology, Department of Translational Research, Laboratory Medicine, Diagnosis and Services, Istituto Giannina Gaslini, Largo Gaslini 5, 16147, Genoa, Italy. alessandreva@ospedale-gaslini.ge.it.
Abstract
BACKGROUND AND AIMS: Glycogen storage disease type Ib (GSD1b) is a rare metabolic and immune disorder caused by a deficiency in the glucose-6-phosphate transporter (G6PT) and characterized by impaired glucose homeostasis, myeloid dysfunction, and long-term risk of hepatocellular adenomas. Despite maximal therapy, based on a strict diet and on granulocyte colony-stimulating factor treatment, long-term severe complications still develop. Understanding the pathophysiology of GSD1b is a prerequisite to develop new therapeutic strategies and depends on the availability of animal models. The G6PT-KO mouse mimics the human disease but is very fragile and rarely survives weaning. We generated a conditional G6PT-deficient mouse as an alternative model for studying the long-term pathophysiology of the disease. We utilized this conditional mouse to develop an inducible G6PT-KO model to allow temporally regulated G6PT deletion by the administration of tamoxifen (TM). METHODS: We generated a conditional G6PT-deficient mouse utilizing the CRElox strategy. Histology, histochemistry, and phenotype analyses were performed at different times after TM-induced G6PT inactivation. Neutrophils and monocytes were isolated and analyzed for functional activity with standard techniques. RESULTS: The G6PT-inducible KO mice display the expected disturbances of G6P metabolism and myeloid dysfunctions of the human disorder, even though with a milder intensity. CONCLUSIONS: TM-induced inactivation of G6PT in these mice leads to a phenotype which mimics that of human GSD1b patients. The conditional mice we have generated represent an excellent tool to study the tissue-specific role of the G6PT gene and the mechanism of long-term complications in GSD1b.
BACKGROUND AND AIMS: Glycogen storage disease type Ib (GSD1b) is a rare metabolic and immune disorder caused by a deficiency in the glucose-6-phosphate transporter (G6PT) and characterized by impaired glucose homeostasis, myeloid dysfunction, and long-term risk of hepatocellular adenomas. Despite maximal therapy, based on a strict diet and on granulocyte colony-stimulating factor treatment, long-term severe complications still develop. Understanding the pathophysiology of GSD1b is a prerequisite to develop new therapeutic strategies and depends on the availability of animal models. The G6PT-KO mouse mimics the human disease but is very fragile and rarely survives weaning. We generated a conditional G6PT-deficient mouse as an alternative model for studying the long-term pathophysiology of the disease. We utilized this conditional mouse to develop an inducible G6PT-KO model to allow temporally regulated G6PT deletion by the administration of tamoxifen (TM). METHODS: We generated a conditional G6PT-deficient mouse utilizing the CRElox strategy. Histology, histochemistry, and phenotype analyses were performed at different times after TM-induced G6PT inactivation. Neutrophils and monocytes were isolated and analyzed for functional activity with standard techniques. RESULTS: The G6PT-inducible KO mice display the expected disturbances of G6P metabolism and myeloid dysfunctions of the human disorder, even though with a milder intensity. CONCLUSIONS:TM-induced inactivation of G6PT in these mice leads to a phenotype which mimics that of humanGSD1bpatients. The conditional mice we have generated represent an excellent tool to study the tissue-specific role of the G6PT gene and the mechanism of long-term complications in GSD1b.
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