Genetic variants that increase the risk of fatty liver disease (FLD) and cirrhosis have recently been identified in the proximity of membrane bound O-acyltransferase domain-containing 7 (MBOAT7). To elucidate the link between these variants and FLD we characterized Mboat7 liver-specific knock-out mice (Mboat7-LSKO). Chow-fed Mboat7-LSKO mice developed fatty livers and associated liver injury. Lipidomic analysis of liver using mass spectrometry revealed a pronounced reduction in 20-carbon polyunsaturated fatty acid content in phosphatidylinositols (PIs), but not in other phospholipids. The change in fatty acid composition of PIs in these mice was associated with a marked increase in de novo lipogenesis due to activation of SREBP-1c, a transcription factor that coordinates the activation of genes encoding enzymes in the fatty acid biosynthesis pathway. Hepatic removal of both SREBP cleavage activating protein (Scap) and Mboat7 normalized hepatic triglycerides relative to Scap only hepatic knock-out showing increased SREBP-1c processing is required for Mboat7 induced steatosis. This study reveals a clear relationship between PI fatty acid composition and regulation of hepatic fat synthesis and delineates the mechanism by which mutations in MBOAT7 cause hepatic steatosis.
BackgroundTumour metastasis to the brain is a common and deadly development in certain cancers; 18–30 % of breast tumours metastasise to the brain. The contribution that gene silencing through epigenetic mechanisms plays in these metastatic tumours is not well understood.ResultsWe have carried out a bioinformatic screen of genome-wide breast tumour methylation data available at The Cancer Genome Atlas (TCGA) and a broad literature review to identify candidate genes that may contribute to breast to brain metastasis (BBM). This analysis identified 82 candidates. We investigated the methylation status of these genes using Combined Bisulfite and Restriction Analysis (CoBRA) and identified 21 genes frequently methylated in BBM. We have identified three genes, GALNT9, CCDC8 and BNC1, that were frequently methylated (55, 73 and 71 %, respectively) and silenced in BBM and infrequently methylated in primary breast tumours. CCDC8 was commonly methylated in brain metastases and their associated primary tumours whereas GALNT9 and BNC1 were methylated and silenced only in brain metastases, but not in the associated primary breast tumours from individual patients. This suggests differing roles for these genes in the evolution of metastatic tumours; CCDC8 methylation occurs at an early stage of metastatic evolution whereas methylation of GANLT9 and BNC1 occurs at a later stage of tumour evolution. Knockdown of these genes by RNAi resulted in a significant increase in the migratory and invasive potential of breast cancer cell lines.ConclusionsThese findings indicate that GALNT9 (an initiator of O-glycosylation), CCDC8 (a regulator of microtubule dynamics) and BNC1 (a transcription factor with a broad range of targets) may play a role in the progression of primary breast tumours to brain metastases. These genes may be useful as prognostic markers and their products may provide novel therapeutic targets.Electronic supplementary materialThe online version of this article (doi:10.1186/s13148-015-0089-x) contains supplementary material, which is available to authorized users.
We present the case of a baby boy, with antenatal finding of bilateral enlarged echogenic lungs, who developed severe postnatal respiratory failure. Two important differential diagnoses, which have an impact on antenatal and postnatal management, are discussed. Fetal ultrasound, MRI and postmortem MRI images are presented and findings correlated with the autopsy findings.
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