Het gaat weer beter met de natuur in Nederland

In een Volkskrantinterview (22 mei 2009) poneerden de eerste drie auteurs de stelling, dat het weer beter gaat met de Nederlandse natuur. Aanleiding vormde de presentatie van de Monitor Duurzaam Nederland (CBS, 2009) waarbij het Planbureau concludeerde dat de biodiversiteit in ons land nog steeds achteruitholt. Dit artikel onderbouwt de stelling van 22 mei en is in feite een vervolg op een eerdere discussie, waarin de methodiek van het PBL werd gepresenteerd. Dit artikel gaat uit van de vraag hoe het gaat met de biodiversiteit en kijkt van daaruit naar de methode

Translational Regulation of Utrophin by miRNAs

Background Utrophin is the autosomal homolog of dystrophin, the product of the Duchenne Muscular Dystrophy (DMD) locus. Its regulation is of therapeutic interest as its overexpression can compensate for dystrophin's absence in animal models of DMD. The tissue distribution and transcriptional regulation of utrophin have been characterized extensively, and more recently translational control mechanisms that may underlie its complex expression patterns have begun to be identified. Methodology/Principal Findings Using a variety of bioinformatic, molecular and cell biology techniques, we show that the muscle isoform utrophin-A is predominantly suppressed at the translational level in C2C12 myoblasts. The extent of translational inhibition is estimated to be ~99% in C2C12 cells and is mediated by both the 5′- and 3′-UTRs of the utrophin-A mRNA. In this study we identify five miRNAs (let-7c, miR-150, miR-196b, miR-296-5p, miR-133b) that mediate the repression, and confirm repression by the previously identified miR-206. We demonstrate that this translational repression can be overcome by blocking the actions of miRNAs, resulting in an increased level of utrophin protein in C2C12 cells. Conclusions/Significance The present study has identified key inhibitory mechanisms featuring miRNAs that regulate utrophin expression, and demonstrated that these mechanisms can be targeted to increase endogenous utrophin expression in cultured muscle cells. We suggest that miRNA-mediated inhibitory mechanisms could be targeted by methods similar to those described here as a novel strategy to increase utrophin expression as a therapy for DMD

Case Report - Hydatid cyst of common bile duct mimicking type 1 choledochal cyst

A 11 year-old girl presented with pain in the abdomen, an abdominal mass and jaundice. Clinical examination and investigations suggested a diagnosis of a type 1 choledochal cyst. Upon operation, a solitary, unruptured hydatid cyst was found obstructing the common bile duct. Intrinsic obstruction of the extrahepatic bile duct by a solitary hyatic cyst without any hepatic involvement as seen in this unique case, has not been reported until now

Hydatid cyst of common bile duct mimicking type 1 choledochal cyst

A 11 year-old girl presented with pain in the abdomen, an abdominal mass and jaundice. Clinical examination and investigations suggested a diagnosis of a type 1 choledochal cyst. Upon operation, a solitary, unruptured hydatid cyst was found obstructing the common bile duct. Intrinsic obstruction of the extrahepatic bile duct by a solitary hyatic cyst without any hepatic involvement as seen in this unique case, has not been reported until now

Cis-Acting Sequence Elements and Upstream Open Reading Frame in Mouse Utrophin-A 5'-UTR Repress Cap-Dependent Translation.

Utrophin, the autosomal homologue of dystrophin can functionally compensate for dystrophin deficiency. Utrophin upregulation could therefore be a therapeutic strategy in Duchenne Muscular Dystrophy (DMD) that arises from mutation in dystrophin gene. In contrast to its transcriptional regulation, mechanisms operating at post-transcriptional level of utrophin expression have not been well documented. Although utrophin-A 5'-UTR has been reported with internal ribosome entry site (IRES), its inhibitory effect on translation is also evident. In the present study we therefore aimed to compare relative contribution of cap-independent and cap-dependent translation with mouse utrophin-A 5'-UTR through m7G-capped and A-capped mRNA transfection based reporter assay. Our results demonstrate that cap-independent translation with utrophin-A 5'-UTR is not as strong as viral IRES. However, cap-independent mode has significant contribution as cap-dependent translation is severely repressed with utrophin-A 5'-UTR. We further identified two sequence elements and one upstream open reading frame in utrophin-A 5'-UTR responsible for repression. The repressor elements in utrophin-A 5'-UTR may be targeted for utrophin upregulation

Comparison between cap-dependent and IRES dependent translation of utrophin-A 5'-UTR containing reporter.

<p>(A) Schematic presentation of monocistronic mRNA pairs used in the assay. Fluc: Firefly luciferase, Rluc: Renilla luciferase. To normalize activities of m7G-capped and A-capped Fluc constructs containing the tested 5'-UTRs, the m7G-capped Rluc was used as reference. (B) Comparison of indicated m7G-capped vs. A-capped monocistronic transcripts in the RNA transfection assay for mouse C2C12 cells, where utrophin-A 5'-UTR is compared with EMCV IRES. The relative A-capped Fluc/m7G-capped Rluc luciferase activity indicates IRES activity of the 5'-UTRs. Results presented as mean±SD (n = 6). Student’s <i>t</i> test was used to analyze the data. The asterisk denotes the statistically significant (P<0.0001) IRES activity of utrophin-A 5'-UTR compared to negative control EMCVmut.</p

Role of upstream open reading frame on the utrophin-A 5'-UTR in m7G-cap-dependent translation.

<p>(A) Schematic presentation of monocistronic mRNAs used in the assay. Fluc: Firefly luciferase, Rluc: Renilla luciferase. To normalize activities of m7G and A-capped Fluc constructs containing the tested 5'-UTRs, the m7G-capped Rluc was used as reference. (B) Expression of m7G and A-capped monocistronic reporter transcripts with 5'-UTRwild and 5'-UTRmut were compared in the RNA transfection assay with mouse C2C12 cells. Upstream AUG in full length 5'-UTR (5'-UTRwild) was mutated to AAG425 in 5'-UTRmut. Results presented as mean±SD (n = 6). Student’s <i>t</i> test was used to analyze the data. The asterisk denotes the statistically significant (P<0.001) difference in normalized luciferase activity. (C) Results of global ribosome profiling study of elongating ribosome available at GWIPS-viz (<a href="http://gwips.ucc.ie" target="_blank">http://gwips.ucc.ie</a>) showed sufficient ribosome accumulation at upstream open reading frame (region 425–452 nt on utrophin-A 5'-UTR) as indicated by higher reads at this region.</p

Deletion analysis of utrophin-A 5'-UTR for identification of repressor elements.

<p>(A) Schematic presentation of monocistronic mRNA pairs used in the assay. Fluc: Firefly luciferase, Rluc: Renilla luciferase. To normalize activities of m7G-capped and A-capped Fluc constructs containing the tested 5'-UTRs, the m7G-capped Rluc was used as reference. (B) Equimolar amount of m7G-capped and A-capped monocistronic transcripts were used in the RNA transfection assay with mouse C2C12 cells. Wild and Δ denote full length and deletion respectively. Results presented as mean±SD (n = 6). Student’s <i>t</i> test was used to analyze the data. The asterisks denote the statistically significant (P<0.0001) difference in relative luciferase activity of m7G-capped transcripts. Deletion of 1–125 nt and 255–302 nt upregulated m7G-cap-dependent expression. No deletion upregulated expression of A-capped transcripts.</p