daf-2
is one of the most studied mutants in
C. elegans
: it contains a deletion in the gene orthologue of the insulin/insulin-like growth factor (IGF) receptor. Using high resolution
1
H NMR ...spectroscopy, metabolomics has helped to dissect the metabolic consequences of altered
daf-2
signalling. Here, we present a detailed metabolomic analysis of
daf-2
, using NMR spectroscopy, gas chromatography mass spectrometry (GC-MS) and liquid chromatography mass spectrometry (LC-MS) to integrate information from different pathways. We have then used Pearson and partial correlation analysis to build networks to explore the central role of
daf-2
in regulating fatty acid and amino acid metabolism. The results show the tight regulation between these two parts of the metabolome.
Pearson and partial correlation analysis was used to build networks to explore the central role of
daf-2
in regulating fatty acid and amino acid metabolism in
Caenorhabditis elegans
.
Regulation of pre-miRNA Processing Lehrbach, Nicolas J.; Miska, Eric A.
Advances in experimental medicine and biology,
2010, Letnik:
700
Book Chapter, Journal Article
Recenzirano
microRNAs are endogenously expressed ∼21 nucleotide noncoding RNAs. microRNA-mediated regulation of the translation of specific mRNA is implicated in a range of developmental processes and ...pathologies. As such, miRNA expression is tightly controlled in normal development by both transcriptional and post-transcriptional mechanisms. This chapter is concerned with the control of pre-miRNA processing of individual miRNAs by specific factors. It is focussed on the regulation of a subset of miRNAs by the RNA-binding protein Lin28/LIN-28. We discuss how Lin28/LIN-28 can sequester pre-let-7 miRNA precursor to prevent Dicer-mediated processing. We describe how interaction of pre-let-7 with Lin28/ LIN-28 leads to pre-let-7 uridylation and subsequent degradation. Finally, we analyze how let-7 and Lin28/LIN-28 together act as a highly conserved developmental switch that controls stem cell differentiation in C. elegans and mammals.
In the nematode Caenorhabditis elegans, different small RNA-dependent gene silencing mechanisms act in the germline to initiate transgenerational gene silencing. Piwi-interacting RNAs (piRNAs) can ...initiate transposon and gene silencing by acting upstream of endogenous short interfering RNAs (siRNAs), which engage a nuclear RNA interference (RNAi) pathway to trigger transcriptional gene silencing. Once gene silencing has been established, it can be stably maintained over multiple generations without the requirement of the initial trigger and is also referred to as RNAe or paramutation. This heritable silencing depends on the integrity of the nuclear RNAi pathway. However, the exact mechanism by which silencing is maintained across generations is not understood. Here we demonstrate that silencing of piRNA targets involves the production of two distinct classes of small RNAs with different genetic requirements. The first class, secondary siRNAs, are localized close to the direct target site for piRNAs. Nuclear import of the secondary siRNAs by the Argonaute HRDE-1 leads to the production of a distinct class of small RNAs that map throughout the transcript, which we term tertiary siRNAs. Both classes of small RNAs are necessary for full repression of the target gene and can be maintained independently of the initial piRNA trigger. Consistently, we observed a form of paramutation associated with tertiary siRNAs. Once paramutated, a tertiary siRNA generating allele confers dominant silencing in the progeny regardless of its own transmission, suggesting germline-transmitted siRNAs are sufficient for multigenerational silencing. This work uncovers a multi-step siRNA amplification pathway that promotes germline integrity via epigenetic silencing of endogenous and invading genetic elements. In addition, the same pathway can be engaged in environmentally induced heritable gene silencing and could therefore promote the inheritance of acquired traits.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
MicroRNAs (miRNAs) are short non-coding RNAs that regulate gene expression in many eukaryotes. miRNAs were first discovered in Caenorhabditis elegans by Victor Ambros' laboratory in 1993. At the same ...time Gary Ruvkun's laboratory identified the first miRNA target gene. Together, these two seminal discoveries identified a novel mechanism of post-transcriptional gene regulation that has been recognized as important for development, physiology and pathology of many organisms. Here we discuss how functional genomic, computational and proteomic approaches complement classical genetic analyses to unravel miRNA biology in C. elegans.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Regulation of pre-miRNA Processing Lehrbach, Nicolas J; Miska, Eric A
Advances in experimental medicine and biology,
2011, Letnik:
700
Journal Article
Recenzirano
microRNAs are endogenously expressed ∼21 nucleotide noncoding RNAs. microRNA-mediated regulation of the translation of specific mRNA is implicated in a range of developmental processes and ...pathologies. As such, miRNA expression is tightly controlled in normal development by both transcriptional and post-transcriptional mechanisms. This chapter is concerned with the control of pre-miRNA processing of individual miRNAs by specific factors. It is focussed on the regulation of a subset of miRNAs by the RNA-binding protein Lin28/LIN-28. We discuss how Lin28/LIN-28 can sequester pre-let-7 miRNA precursor to prevent Dicer-mediated processing. We describe how interaction of pre-let-7 with Lin28/ LIN-28 leads to pre-let-7 uridylation and subsequent degradation. Finally, we analyze how let-7 and Lin28/LIN-28 together act as a highly conserved developmental switch that controls stem cell differentiation in C. elegans and mammals.
Here we report that transcriptional effects of the insertion of a retrotransposon can occur simultaneously both upstream and downstream of the insertion site. We have identified an intra-cisternal A ...particle (IAP) retrotransposon in intron 6 of a gene that we have named Cabp (CDK5 activator binding protein). The presence of the IAP is associated with an aberrant transcript initiating from a cryptic promoter in the IAP, reading out into the adjacent Cabp gene sequence. The expression of this transcript is highly variable among isogenic mice within the C57BL/6J strain and so CabpIAP can be classified as a metastable epiallele. As expected, the presence or absence of the transcript correlates with differential DNA methylation of the 5′ LTR of the IAP. More surprisingly, in mice where the retrotransposon is unmethylated and presumably transcriptionally active, we find a number of short Cabp transcripts which initiate at the normal 5′ end of the gene but terminate prematurely, just 5′ of the retrotransposon. This is the first report of a retrotransposon having both upstream and downstream effects on transcription at the site of insertion and it suggests that alternative polyadenylation may sometimes be caused by a downstream convergent transcription unit.
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