Martin Et Al 2010 Related Keywords - Martin Et Al 2010 Long
Next, we asked whether H19 depletion would produce a phenotype that mimics let-7 overexpression. Thus, differentiating C2C12 myoblasts were transfected with siCon, simH19, or let-7, followed by the assessment of myogenic differentiation. Both H19 depletion and let-7 overexpression led to significantly increased expression of muscle differentiation markers myosin heavy chain and myogenin at day 4 of differentiation (, left panel, compare lanes 2 and 3 to lane 1 in the top and middle blots; and right panel, compare green and purple bars to blue bars), suggesting enhanced myogenesis. Consistent with this finding, we observed increased multinucleated myotube formation in simH19- and let-7-transfected myoblasts (, compare right two panels to the left). This was reflected quantitatively as an increase in the fusion index as compared with siCon-transfected myoblasts (). Together, these results underscore the physiological significance of the H19-let-7 interaction while uncovering a previously unexpected regulatory network involving the H19/let-7 axis in myogenic differentiation.
BioEssays 6/2010, BioEssays | DeepDyve
The consequence of this is that I do spend more time than most out of sight behind a closed door, so get to hear the comings and goings of others as they use the facilities unseen. I hear them come in, position themselves at the urinals, and release their streams. Sometimes you hear only one person at a time and sometimes you can hear more. After they’ve wetted that wall I’ve noticed that people behave differently, depending on how many others are in the toilet at the same time and where they are.
To confirm that the observed effects were indeed due to impaired let-7 function, transfection experiments using iLet-7 (or iCon as a negative control) were performed. As expected, increased protein levels of both DICER and HMGA2 were observed in iLet-7 treated vs. iCon-treated HEK293 cells (, left panel, compare lane 2 to lane 1 in the top two blots). Further, when pH19mut in which all four let-7 binding sites were inactivated was used, derepression of Dicer and Hmga2 was not observed (, right panel, compare lane 2 to lane 1 in the top two blots), despite the fact that the mutant H19 was expressed at a level comparable to that of wild-type H19 (, compare the left second to the last column). Again, the mRNA levels of Dicer and Hmga2 were not affected (), consistent with previous reports of translational repression without RNA destabilization (; ) and context-dependent miRNA effects (; ). These data suggest that the predicted let-7 binding sites in H19 are required for derepression of endogenous targets. Finally, derepression of DICER and HMGA2 in response to ectopic H19 expression was also observed when primary cultures of human umbilical vein endothelial cells (HUVEC) were tested (). Taken together, these results strongly suggest that derepression of endogenous let-7 targets Dicer and Hmga2 was due to a direct “sponge” effect of H19.
The Imprinted H19 LncRNA Antagonizes Let-7 MicroRNAs
Reviewing the evidence
he just walked up to me as if it was an hour ago
my legs were shaking
Oh he sang better than you.
It’s gonna bring tears to your eyes, I promise you
I’m just practising, excuse me
Yes I still want that
Falls asleep ’til about 9 o’clock
I found a number of dirty shirts in the wardrobe
Always going to collect money
I couldn’t fault him on that
I told you that the other day
He thought I was bloody thick
It was all in my head
I failed my MOT test
Physiological roles of long noncoding RNAs: insight …
The H19 gene belongs to a highly conserved imprinted gene cluster that plays important roles in embryonal development and growth control (). The cluster also contains the nearby reciprocally imprinted gene for insulin-like growth factor 2 (Igf2) that is coordinately regulated by an intergenic control region and a common enhancer region. In human and mouse, H19 is expressed from the maternal allele, while Igf2 is paternally expressed. H19 expression is strongly induced during embryogenesis and down-regulated after birth, except in adult skeletal muscle and heart (; ). Two human genetic disorders have been linked to the H19-Igf2 locus: Silver-Russell Syndrome and Beckwith-Wiedemann Syndrome, with the latter also displaying higher susceptibility to the development of embryonal tumors (). Further, a role of H19 acting either as a tumor suppressor () or an oncogene () has been suggested. However, how H19 functions to impact these various processes remains poorly understood.
Physiological roles of long noncoding RNAs: ..
The human H19 encodes a predominantly cytoplasmic ~2.3-kilobase long capped, spliced, and polyadenylated RNA that produces no known protein product (). In the past two decades, extensive investigations using both deletion and transgenic mouse models have yielded important insights into the functional role of H19 (). It has been reported that mice with targeted H19 deletion (H19Δ3) exhibit an overgrowth phenotype (an increase in postnatal growth by 8% compared to wt littermates), which was restored to wt growth by transgenic expression of H19 (). Importantly, overexpression of several genes of the imprinted gene network (IGN) (), including Igf2 in the H19Δ3 mice was concomitantly restored to the wt level by such transgenic expression. This suggests that the H19 lncRNA acts in trans to regulate the IGN and control growth in mice (). However, the mechanism by which H19 does so is unclear. Recently, a role of H19 in limiting placental growth through its encoded miR675 has been reported (). This microRNA (miRNA) is produced from full-length H19 through Drosha processing and the miRNA is detected only in the mouse placenta and at a time window where placental growth normally ceases (). Finally, high H19 expression has been detected in adult skeletal muscle of both human and mouse (; ), but the physiological significance of this expression remains to be investigated. In the current study, we demonstrate that the H19 lncRNA acts as a molecular sponge for the major let-7 family of miRNAs, which are known to play important roles in diverse physiological and pathological processes.