Spatio-temporal regulation of circular RNA expression during porcine embryonic brain development
GENOME BIOLOGY
Authors: Veno, Morten T.; Hansen, Thomas B.; Veno, Susanne T.; Clausen, Bettina H.; Grebing, Manuela; Finsen, Bente; Holm, Ida E.; Kjems, Jorgen
Abstract
Background: Recently, thousands of circular RNAs (circRNAs) have been discovered in various tissues and cell types from human, mouse, fruit fly and nematodes. However, expression of circRNAs across mammalian brain development has never been examined. Results: Here we profile the expression of circRNA in five brain tissues at up to six time-points during fetal porcine development, constituting the first report of circRNA in the brain development of a large animal. An unbiased analysis reveals a highly complex regulation pattern of thousands of circular RNAs, with a distinct spatio-temporal expression profile. The amount and complexity of circRNA expression was most pronounced in cortex at day 60 of gestation. At this time-point we find 4634 unique circRNAs expressed from 2195 genes out of a total of 13,854 expressed genes. Approximately 20 % of the porcine splice sites involved in circRNA production are functionally conserved between mouse and human. Furthermore, we observe that "hot-spot" genes produce multiple circRNA isoforms, which are often differentially expressed across porcine brain development. A global comparison of porcine circRNAs reveals that introns flanking circularized exons are longer than average and more frequently contain proximal complementary SINEs, which potentially can facilitate base pairing between the flanking introns. Finally, we report the first use of RNase R treatment in combination with in situ hybridization to show dynamic subcellular localization of circRNA during development. Conclusions: These data demonstrate that circRNAs are highly abundant and dynamically expressed in a spatio-temporal manner in porcine fetal brain, suggesting important functions during mammalian brain development.
New insights into tardive dyskinesia genetics: Implementation of whole-exome sequencing approach
PROGRESS IN NEURO-PSYCHOPHARMACOLOGY & BIOLOGICAL PSYCHIATRY
Authors: Alkelai, Anna; Greenbaum, Lior; Heinzen, Erin L.; Baugh, Evan H.; Teitelbaum, Alexander; Zhu, Xiaolin; Strous, Rael D.; Tatarskyy, Pavel; Zai, Clement C.; Tiwari, Arun K.; Tampakeras, Maria; Freeman, Natalie; Mueller, Daniel J.; Voineskos, Aristotle N.; Lieberman, Jeffrey A.; Delaney, Shannon L.; Meltzer, Herbert Y.; Remington, Gary; Kennedy, James L.; Pulver, Ann E.; Peabody, Emma P.; Levy, Deborah L.; Lerer, Bernard
Abstract
Tardive dyskinesia (TD) is an adverse movement disorder induced by chronic treatment with antipsychotics drugs. The contribution of common genetic variants to TD susceptibility has been investigated in recent years, but with limited success. The aim of the current study was to investigate the potential contribution of rare variants to TD vulnerability. In order to identify TD risk genes, we performed whole-exome sequencing (WES) and gene-based collapsing analysis focusing on rare (allele frequency < 1%) and putatively deleterious variants (qualifying variants). 82 Jewish schizophrenia patients chronically treated with antipsychotics were included and classified as having severe TD or lack of any abnormal movements based on a rigorous definition of the TD phenotype. First, we performed a case-control, exome-wide collapsing analysis comparing 39 schizophrenia patients with severe TD to 3118 unrelated population controls. Then, we checked the potential top candidate genes among 43 patients without any TD manifestations. All the genes that were found to harbor one or more qualifying variants in patients without any TD features were excluded from the final list of candidate genes. Only one gene, regulating synaptic membrane exocytosis 2 (RIMS2), showed significant enrichment of qualifying variants in TD patients compared with unrelated population controls after correcting for multiple testing (Fisher's exact test p = 5.32E-08, logistic regression p = 2.50E-08). Enrichment was caused by a single variant (rs567070433) due to a frameshift in an alternative transcript of RIMS2. None of the TD negative patients had qualifying variants in this gene. In a validation cohort of 140 schizophrenia patients assessed for TD, the variant was also not detected in any individual. Some potentially suggestive TD genes were detected in the TD cohort and warrant follow-up in future studies. No significant enrichment in previously reported TD candidate genes was identified. To the best of our knowledge, this is the first WES study of TD, demonstrating the potential role of rare loss-of-function variant enrichment in this pharmacogenetic phenotype.