Project description:The emergence and transmission of epigenetic signals across generations can quickly and efficiently alter gene expression in a population. We describe an epigenetic silencing signal whose initiation, transmission properties, genetic requirements and site of action are distinct from previously described epigenetic inheritance in C. elegans. A multi-copy transgene containing the region upstream of sid-1 silences sid-1 and upstream genes. Once established, silencing is stable in the absence of the array and can be maintained without selection for 13 generations. We show that the silenced state can be transmitted to progeny in the absence of the silenced locus, but that inherited silencing is dependent on the nuclear RNAi Argonaute HRDE-1, which stabilizes silencing siRNAs that target sid-1 exons. Notably, at each generation, the RNAi-dependent germline silenced sid-1 locus transitions to a chromatin-dependent silenced state in somatic cells, indicating that the mechanisms of transgenerational silencing in the soma and germline are distinct.
Project description:The emergence and transmission of epigenetic signals across generations can quickly and efficiently alter gene expression in a population. We describe an epigenetic silencing signal whose initiation, transmission properties, genetic requirements and site of action are distinct from previously described epigenetic inheritance in C. elegans. A multi-copy transgene containing the region upstream of sid-1 silences sid-1 and upstream genes. Once established, silencing is stable in the absence of the array and can be maintained without selection for 13 generations. We show that the silenced state can be transmitted to progeny in the absence of the silenced locus, but that inherited silencing is dependent on the nuclear RNAi Argonaute HRDE-1, which stabilizes silencing siRNAs that target sid-1 exons. Notably, at each generation, the RNAi-dependent germline silenced sid-1 locus transitions to a chromatin-dependent silenced state in somatic cells, indicating that the mechanisms of transgenerational silencing in the soma and germline are distinct.
Project description:The importance of transgenerationally inherited epigenetic states to organismal fitness remains unknown as well-documented examples are often not amenable to mechanistic analysis or rely on artificial reporter loci. Here we describe an induced silenced state at an endogenous locus that persists, at 100% transmission without selection, for up to 13 generations. This unusually persistent silencing enables a detailed molecular genetic analysis of an inherited epigenetic state. We find that silencing is dependent on germline nuclear RNAi factors and post-transcriptional mechanisms. Consistent with these later observations, inheritance does not require the silenced locus, and we provide genetic evidence that small RNAs embody the inherited silencing signal. Notably, heritable germline silencing directs somatic epigenetic silencing. Somatic silencing does not require somatic nuclear RNAi but instead requires both maternal germline nuclear RNAi and chromatin-modifying activity. Coupling inherited germline silencing to somatic silencing may enable selection for physiologically important traits.
Project description:To define what genes are predominantly or specifically expressed in either soma or germline in C. elegans adults, total RNA was extracted from germline-less glp-4 mutant animals or from dissected gonads, respectively. Total RNA sequencing was peformed in duplicates. Four samples in total.
Project description:To define what genes are predominantly or specifically expressed in either soma or germline in C. elegans adults, total RNA was extracted from germline-less glp-4 mutant animals or from dissected gonads, respectively.
Project description:SIRT1, a known regulator of cellular senescence, is a therapeutic target for age related disorders and its upregulation is a strategy to improve the cell therapeutic potentials of human mesenchymal stem cell (MSCs). Knockdown of natural antisense transcripts via small activating RNAs (RNAa) is an emerging approach for safe and locus specific gene regulation. We have recently identified a natural antisense transcript at human SIRT1 locus (SIRT1-NAT), the expression of which shows a negative correlation with that of SIRT1. To test the hypothetic upregulation of SIRT1 via knockdown of SIRT1-NAT, in this study we designed a single stranded oligonucleotide (SIRT1-antagoNAT) against the antisense transcript, transfection of which efficiently knocked down the SIRT1-NAT and induced SIRT1 transcription in human MSCs. In addition, activation of SIRT1 transfection via knockdown of SIRT1-NAT in human MSCs enhanced their proliferation and differentiation potentials, reduced senescence associated β-galactosidase activity and reversed the senescence associated molecular alterations. Our findings introduce an RNAa mediated approach for epigenetic induction of endogenous SIRT1 and the consequent attenuation of senescence. Further studies should evaluate the therapeutic potentials of this approach against various age related disorders.