title: Gestation under chronic constant light leads to extensive gene expression changes in the fetal rat liver.
abstract: Recent reports account for altered metabolism in adult offspring from pregnancy subjected to abnormal photoperiod, suggesting fetal programming of liver physiology. To generate a pipeline of subsequent mechanistic experiments addressing strong candidate genes, here we investigated the effects of constant gestational light on the fetal liver transcriptome. At 10 days of gestation, dams were randomized in two groups (n = 7 each): constant light (LL) and normal photoperiod (12 h light/12 h dark; LD). At 18 days of gestation, RNA was isolated from the fetal liver and subjected to DNA microarray (Affymetrix platform for 28,000 genes). Selected differential mRNAs were validated by quantitative PCR (qPCR), while integrated transcriptional changes were analyzed with Ingenuity Pathway Analysis and other bioinformatics tools. Comparison of LL relative to LD fetal liver led to the following findings. Significant differential expression was found for 3,431 transcripts (1,960 upregulated and 1,471 downregulated), with 393 of them displaying ≥ 1.5-fold change. We validated 27 selected transcripts by qPCR, which displayed fold-change values highly correlated with microarray (r(2) = 0.91). Different markers of nonalcoholic fatty liver disease were either upregulated (e.g., Ndn and Pnpla3) or downregulated (e.g., Gnmt, Bhmt1/2, Sult1a1, Mpo, and Mat1a). Diverse pathways were altered, including hematopoiesis, coagulation cascade, complement system, and carbohydrate and lipid metabolism. The microRNAs 7a-1, 431, 146a, and 153 were upregulated, while the abundant hepatic miRNA 122 was downregulated. Constant gestational light induced extensive modification of the fetal liver transcriptome. A number of differentially expressed transcripts belong to fundamental functional pathways, potentially contributing to long-term liver disease.
authors.affiliation: Laboratory of Developmental Chronobiology, Institute of Anatomy, Histology and Pathology, Faculty of Medicine, Universidad Austral de Chile, Valdivia, Chile.
authors.forename: Carlos
authors.initials: C
authors.lastname: Spichiger
authors.affiliation: Laboratory of Developmental Chronobiology, Institute of Anatomy, Histology and Pathology, Faculty of Medicine, Universidad Austral de Chile, Valdivia, Chile.
authors.forename: Claudia
authors.initials: C
authors.lastname: Torres-Farfan
authors.affiliation: Laboratory of Developmental Chronobiology, Institute of Anatomy, Histology and Pathology, Faculty of Medicine, Universidad Austral de Chile, Valdivia, Chile.
authors.forename: Hugo A
authors.initials: HA
authors.lastname: Galdames
authors.affiliation: Laboratory of Developmental Chronobiology, Institute of Anatomy, Histology and Pathology, Faculty of Medicine, Universidad Austral de Chile, Valdivia, Chile.
authors.forename: Natalia
authors.initials: N
authors.lastname: Mendez
authors.affiliation: Laboratory of Developmental Chronobiology, Institute of Anatomy, Histology and Pathology, Faculty of Medicine, Universidad Austral de Chile, Valdivia, Chile.
authors.forename: Pamela
authors.initials: P
authors.lastname: Alonso-Vazquez
authors.affiliation: Laboratory of Developmental Chronobiology, Institute of Anatomy, Histology and Pathology, Faculty of Medicine, Universidad Austral de Chile, Valdivia, Chile hrichter@uach.cl.
authors.forename: Hans G
authors.identifier: http://orcid.org/0000-0002-7224-9388
authors.initials: HG
authors.lastname: Richter
mesh_terms: D000818:Animals; D005260:Female; D005333:Fetus; D005786:Gene Expression Regulation / Q000235:genetics / Q000502:physiology; D008027:Light; D050356:Lipid Metabolism / Q000235:genetics; D008099:Liver; D008107:Liver Diseases / Q000378:metabolism*; D035683:MicroRNAs / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D011247:Pregnancy; D051381:Rats
chemical_list: D035683:MicroRNAs
keywords: constant gestational light; fetal development; liver gene networks; metabolic pathways; whole genome