Copy-Number Variation of the Glucose Transporter Gene SLC2A3 and Congenital Heart Defects in the 22q11.2 Deletion Syndrome
AMERICAN JOURNAL OF HUMAN GENETICS
Authors: Mlynarski, Elisabeth E.; Sheridan, Molly B.; Xie, Michael; Guo, Tingwei; Racedo, Silvia E.; McDonald-McGinn, Donna M.; Gai, Xiaowu; Chow, Eva W. C.; Vorstman, Jacob; Swillen, Ann; Devriendt, Koen; Breckpot, Jeroen; Digilio, Maria Cristina; Marino, Bruno; Dallapiccola, Bruno; Philip, Nicole; Simon, Tony J.; Roberts, Amy E.; Piotrowicz, Malgorzata; Bearden, Carrie E.; Eliez, Stephan; Gothelf, Doron; Coleman, Karlene; Kates, Wendy R.; Devoto, Marcella; Zackai, Elaine; Heine-Suner, Damian; Shaikh, Tamim H.; Bassett, Anne S.; Goldmuntz, Elizabeth; Morrow, Bernice E.; Emanuel, Beverly S.
Abstract
The 22q11.2 deletion syndrome (22q11DS; velocardiofacial/DiGeorge syndrome; VCFS/DGS) is the most common microdeletion syndrome and the phenotypic presentation is highly variable. Approximately 65% of individuals with 22q11DS have a congenital heart defect (CHD), mostly of the conotruncal type, and/or an aortic arch defect. The etiology of this phenotypic variability is not currently known. We hypothesized that copy-number variants (CNVs) outside the 22q11.2 deleted region might increase the risk of being born with a CHD in this sensitized population. Genotyping with Affymetrix SNP Array 6.0 was performed on two groups of subjects with 22q11DS separated by time of ascertainment and processing. CNV analysis was completed on a total of 949 subjects (cohort 1, n = 562; cohort 2, n = 387), 603 with CHDs (cohort 1, n = 363; cohort 2, n = 240) and 346 with normal cardiac anatomy (cohort 1, n = 199; cohort 2, n = 147). Our analysis revealed that a duplication of SLC2A3 was the most frequent CNV identified in the first cohort. It was present in 18 subjects with CHDs and 1 subject without (p = 3.12 x 10(-3), two-tailed Fisher's exact test). In the second cohort, the SLC2A3 duplication was also significantly enriched in subjects with CHDs (p = 3.30 x 10(-2), two-tailed Fisher's exact test). The SLC2A3 duplication was the most frequent CNV detected and the only significant finding in our combined analysis (p = 2.68 x 10(-4), two-tailed Fisher's exact test), indicating that the SLC2A3 duplication might serve as a genetic modifier of CHDs and/or aortic arch anomalies in individuals with 22q11DS.
Multiple facilitated glucose transporters SLC2As are required for normal mouse preimplantation embryo development
AMERICAN JOURNAL OF TRANSLATIONAL RESEARCH
Authors: Arhin, Samuel Kofi; Zhao, Junzhao; Ji, Xu; Shi, Changgeng; Tang, Jianan; Gu, Yihua; Xi, Haitao; Cheng, Jing; Qu, Xianqin; Shi, Huijuan; Jin, Xingliang; Lv, Jieqiang
Abstract
Background: Glucose metabolism is an essential energy source for mammalian preimplantation embryonic development. Therefore, we aimed to analyze the expression of all 12 known glucose transporters (facilitated solute carrier family 2, Slc2a) during early mouse embryo development. Methods: Gene and protein expression of Slc2a transporters in oocytes and embryos were assessed by the TaqMan gene expression assay and confocal immunofluorescence, respectively. Results: Except for Slc2a2, the other 11 Slc2a transcripts were detected in oocytes. Transcripts of Slc2a1, Slc2a3, Slc2a4, and Slc2a8 were the most enriched and detected in preimplantation embryos. The transcription of other Slc2a isoforms was barely detectable or absent after fertilization; however, they were detected in blastocysts, except for Slc2a10 and Slc2a13. Embryo culture in the simple defined medium caused a reduction in transcription of Slc2a1, Slc2a3, Slc2a4, and Slc2a8 in blastocyst; yet, amino acids partially reversed this impaired transcription of Slc2a1 and Slc2a4. SLC2A1 and SLC2A4 proteins were detected at all embryonic stages with nuclear accumulation in the embryos at the early cleavage stage. SLC2A3 and SLC2A8 were not detected in embryos until the eight cell stage. The cellular membrane localization of SLC2A1, SLC2A3, and SLC2A8 occurred after compaction and was characterized in blastocysts. SLC2A4 was evenly distributed in the cytoplasm and nuclei without its characteristic membrane localization. Indinavir sulfate (a SLC2A4 inhibitor) decreased the rate of development and prevented glucose utilization in embryos after compaction. These inhibitory activities were partially reversed by exogenous insulin. Conclusion: The results unveil distinct expression patterns of individual Slc2a glucose transporters during early embryo development. Taken together, they provide novel insights into the understanding and management of glucose metabolic infertility in assisted-reproductive technologies (ART).