title: Type 2 diabetes mellitus induces congenital heart defects in murine embryos by increasing oxidative stress, endoplasmic reticulum stress, and apoptosis.
abstract: Maternal type 1 and 2 diabetes mellitus are strongly associated with high rates of severe structural birth defects, including congenital heart defects. Studies in type 1 diabetic embryopathy animal models have demonstrated that cellular stress-induced apoptosis mediates the teratogenicity of maternal diabetes leading to congenital heart defect formation. However, the mechanisms underlying maternal type 2 diabetes mellitus-induced congenital heart defects remain largely unknown.
  
  
  
  We aim to determine whether oxidative stress, endoplasmic reticulum stress, and excessive apoptosis are the intracellular molecular mechanisms underlying maternal type 2 diabetes mellitus-induced congenital heart defects.
  
  
  
  A mouse model of maternal type 2 diabetes mellitus was established by feeding female mice a high-fat diet (60% fat). After 15 weeks on the high-fat diet, the mice showed characteristics of maternal type 2 diabetes mellitus. Control dams were either fed a normal diet (10% fat) or the high-fat diet during pregnancy only. Female mice from the high-fat diet group and the 2 control groups were mated with male mice that were fed a normal diet. At E12.5, embryonic hearts were harvested to determine the levels of lipid peroxides and superoxide, endoplasmic reticulum stress markers, cleaved caspase 3 and 8, and apoptosis. E17.5 embryonic hearts were harvested for the detection of congenital heart defect formation using India ink vessel patterning and histological examination.
  
  
  
  Maternal type 2 diabetes mellitus significantly induced ventricular septal defects and persistent truncus arteriosus in the developing heart, along with increasing oxidative stress markers, including superoxide and lipid peroxidation; endoplasmic reticulum stress markers, including protein levels of phosphorylated-protein kinase RNA-like endoplasmic reticulum kinase, phosphorylated-IRE1α, phosphorylated-eIF2α, C/EBP homologous protein, and binding immunoglobulin protein; endoplasmic reticulum chaperone gene expression; and XBP1 messenger RNA splicing, as well as increased cleaved caspase 3 and 8 in embryonic hearts. Furthermore, maternal type 2 diabetes mellitus triggered excessive apoptosis in ventricular myocardium, endocardial cushion, and outflow tract of the embryonic heart.
  
  
  
  Similar to those observations in type 1 diabetic embryopathy, maternal type 2 diabetes mellitus causes heart defects in the developing embryo manifested with oxidative stress, endoplasmic reticulum stress, and excessive apoptosis in heart cells.
authors.affiliation: Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Maryland School of Medicine, Baltimore, MD.
authors.forename: Yanqing
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Maryland School of Medicine, Baltimore, MD; Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD.
authors.forename: E Albert
authors.initials: EA
authors.lastname: Reece
authors.affiliation: Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Maryland School of Medicine, Baltimore, MD.
authors.forename: Jianxiang
authors.initials: J
authors.lastname: Zhong
authors.affiliation: Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Maryland School of Medicine, Baltimore, MD.
authors.forename: Daoyin
authors.initials: D
authors.lastname: Dong
authors.affiliation: Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Maryland School of Medicine, Baltimore, MD.
authors.forename: Wei-Bin
authors.initials: WB
authors.lastname: Shen
authors.affiliation: Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Maryland School of Medicine, Baltimore, MD.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Harman
authors.affiliation: Department of Obstetrics, Gynecology, and Reproductive Sciences, University of Maryland School of Medicine, Baltimore, MD; Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, Baltimore, MD. Electronic address: pyang@fpi.umaryland.edu.
authors.forename: Peixin
authors.initials: P
authors.lastname: Yang
mesh_terms: D000818:Animals; D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism; D053181:Caspase 8 / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental; D016640:Diabetes, Gestational; D004622:Embryo, Mammalian; D004721:Endoplasmic Reticulum / Q000378:metabolism; D000091342:Endoplasmic Reticulum Chaperone BiP; D059865:Endoplasmic Reticulum Stress; D004722:Endoribonucleases / Q000378:metabolism; D005260:Female; D006330:Heart Defects, Congenital / Q000196:embryology* / Q000473:pathology; D006360:Heat-Shock Proteins / Q000378:metabolism; D015227:Lipid Peroxidation; D008810:Mice, Inbred C57BL; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D018384:Oxidative Stress; D010766:Phosphorylation; D011247:Pregnancy; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D012326:RNA Splicing; D051742:Transcription Factor CHOP / Q000378:metabolism; D000071717:X-Box Binding Protein 1 / Q000235:genetics
chemical_list: D000091342:Endoplasmic Reticulum Chaperone BiP; D006360:Heat-Shock Proteins; D000071717:X-Box Binding Protein 1; C000605544:Xbp1 protein, mouse; D051742:Transcription Factor CHOP; D011494:Protein Kinases; C510185:Ern1 protein, mouse; D017346:Protein Serine-Threonine Kinases; C531557:eIF2alpha kinase, mouse; D004722:Endoribonucleases; C505526:Casp8 protein, mouse; D053148:Caspase 3; D053181:Caspase 8
keywords: apoptosis; endoplasmic reticulum stress; heart defects; oxidative stress; type 2 diabetes mellitus