title: Glycogen-branching enzyme deficiency leads to abnormal cardiac development: novel insights into glycogen storage disease IV.
abstract: Glycogen storage disease type IV (GSD-IV) is an autosomal recessive disease caused by a deficiency in glycogen-branching enzyme (GBE1) activity that results in the accumulation of amylopectin-like polysaccharide, which presumably leads to osmotic swelling and cell death. This disease is extremely heterogeneous in terms of tissue involvement, age of onset and clinical manifestation. The most severe fetal form presents as hydrops fetalis; however, its pathogenetic mechanisms are largely unknown. In this study, mice carrying a stop codon mutation (E609X) in the Gbe1 gene were generated using a gene-driven mutagenesis approach. Homozygous mutants (Gbe(-/-) mice) recapitulated the clinical features of hydrops fetalis and the embryonic lethality of the severe fetal form of GSD-IV. However, contrary to conventional expectations, little amylopectin accumulation and no cell degeneration were found in Gbe(-/-) embryonic tissues. Glycogen accumulation was reduced in developing hearts of Gbe(-/-)embryos, and abnormal cardiac development, including hypertrabeculation and noncompaction of the ventricular wall, was observed. Further, Gbe1 ablation led to poor ventricular function in late gestation and ultimately caused heart failure, fetal hydrops and embryonic lethality. We also found that the cell-cycle regulators cyclin D1 and c-Myc were highly expressed in cardiomyocytes and likely contributed to cardiomyocyte proliferation and trabeculation/compaction of the ventricular wall. Our results reveal that early molecular events associated with Gbe1 deficiency contribute to abnormal cardiac development and fetal hydrops in the fetal form of GSD-IV.
authors.affiliation: Institute of Biomedical Sciences, Academia Sinica, Taipei 11529, Taiwan.
authors.forename: Yi-Ching
authors.initials: YC
authors.lastname: Lee
authors.forename: Chia-Jung
authors.initials: CJ
authors.lastname: Chang
authors.forename: Deeksha
authors.initials: D
authors.lastname: Bali
authors.forename: Yuan-Tsong
authors.initials: YT
authors.lastname: Chen
authors.forename: Yu-Ting
authors.initials: YT
authors.lastname: Yan
mesh_terms: D015061:1,4-alpha-Glucan Branching Enzyme / Q000172:deficiency* / Q000235:genetics*; D000687:Amylopectin / Q000378:metabolism; D000818:Animals; D018797:Cell Cycle Proteins / Q000235:genetics; D049109:Cell Proliferation; D018388:Codon, Terminator; D019938:Cyclin D1 / Q000235:genetics; D020964:Embryo Loss; D005455:Fluorescent Antibody Technique; D016259:Genes, myc; D006003:Glycogen / Q000378:metabolism*; D006011:Glycogen Storage Disease Type IV / Q000196:embryology / Q000235:genetics* / Q000378:metabolism; D006321:Heart / Q000196:embryology*; D006330:Heart Defects, Congenital / Q000235:genetics* / Q000378:metabolism; D006333:Heart Failure; D006339:Heart Rate; D015160:Hydrops Fetalis; D051379:Mice; D032383:Myocytes, Cardiac; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D016276:Ventricular Function
chemical_list: D018797:Cell Cycle Proteins; D018388:Codon, Terminator; D019938:Cyclin D1; D006003:Glycogen; D000687:Amylopectin; D015061:1,4-alpha-Glucan Branching Enzyme