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Today, The Visible Embryo is linked to over 600 educational institutions and is viewed by more than 1 million visitors each month. The field of early embryology has grown to include the identification of the stem cell as not only critical to organogenesis in the embryo, but equally critical to organ function and repair in the adult human. The identification and understanding of genetic malfunction, inflammatory responses, and the progression in chronic disease, begins with a grounding in primary cellular and systemic functions manifested in the study of the early embryo.

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Pregnancy Timeline by SemestersFetal liver is producing blood cellsHead may position into pelvisBrain convolutions beginFull TermWhite fat begins to be madeWhite fat begins to be madeHead may position into pelvisImmune system beginningImmune system beginningPeriod of rapid brain growthBrain convolutions beginLungs begin to produce surfactantSensory brain waves begin to activateSensory brain waves begin to activateInner Ear Bones HardenBone marrow starts making blood cellsBone marrow starts making blood cellsBrown fat surrounds lymphatic systemFetal sexual organs visibleFinger and toe prints appearFinger and toe prints appearHeartbeat can be detectedHeartbeat can be detectedBasic Brain Structure in PlaceThe Appearance of SomitesFirst Detectable Brain WavesA Four Chambered HeartBeginning Cerebral HemispheresFemale Reproductive SystemEnd of Embryonic PeriodEnd of Embryonic PeriodFirst Thin Layer of Skin AppearsThird TrimesterSecond TrimesterFirst TrimesterFertilizationDevelopmental Timeline
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Home | Pregnancy Timeline | News Alerts |News Archive Sep 10, 2013

 

RNA splicing

Pre-mRNA_to_mRNA

This process of cutting and joining different pieces of RNA is called splicing,
and the proteins that mediate splicing are known as splicing factors.







nuclear domains

WHO Child Growth Charts

 

 

 

Discovered: new RNA pathway in human embryonic stem cells

Discovery of RNA regulator could lead to a better understanding of diseases like cancer and influenza.

Scientists at A*STAR’s Genome Institute of Singapore (GIS), in collaboration with their counterparts from Canada, Hong Kong and US, have discovered a protein mediator called SON, which plays a critical role in the health and proper functioning of human embryonic stem cells (hESCs).

This finding was reported on 8th September 2013 in the advanced online issue of the prestigious science journal Nature Cell Biology.


Correct expression of genes is essential for a cell to stay alive and to perform other cellular and physiological functions.

During gene expression, DNA is first converted into RNA transcript and then some parts of it are removed while others are joined before the trimmed RNA transcript can be translated into proteins.

This process of cutting and joining different pieces of RNA is called splicing, and the proteins that mediate splicing are known as splicing factors.


Mutations in splicing factors can cause diseases such as myotonic dystrophy and cancer. Even though hESCs have been studied extensively over the last decade due to their potential to differentiate into cell-types of potential clinical applications, little is known about the role that splicing plays in the regulation of pluripotency in these cells.

Scientists at the GIS followed their previous study on a genome-wide investigation of gene functions in hESCs, which was published in Nature [Chia et al. 2010. 468(7321):316-20], and found that splicing factors, such as the protein known as SON, are key regulators of hESC maintenance.


SON was discovered to be essential for converting differentiated cells into pluripotent stem cells.

In addition, SON promotes correct splicing of a particular group of RNAs, including those coding for essential hESC regulators, and thereby helps hESCs to survive in an undifferentiated state.

Moreover, the authors showed that silencing of SON induced new transcript isoforms that seemed to be non-functional in hESCs.


The study, led by GIS Executive Director Prof Ng Huck Hui, establishes an initial connection between splicing and pluripotency in hESCs and contributes to the comprehensive understanding of the nature of hESCs. Besides its role in hESCs, SON was previously found to be involved in the development of leukemia and influenza virus infection.

Prof Ng Huck Hui states: “Maintenance and differentiation of human embryonic stem cells are governed by an intricate network of diverse cell processes. In the past, we focused on transcriptional regulation. In our new study, it is clear that splicing contributes to the unique cellular state of hESCs, explained in part through the function of a protein known as SON regulating the precise splicing of transcripts important to pluripotency.

Dr Alan Colman, the former Executive Director of the Singapore Stem Cell Consortium, adds: “In this new manuscript, Ng Huck Hui and colleagues continue to cement their position at the forefront of pluripotency research worldwide.”


“The distinctive feature of human embryonic stem cells is their ability to either self renew or, given the right conditions, to differentiate into all the cell types that comprise the adult body.

"In previous work, the team uncovered a number of unique transcription factors mediating the maintenance of pluripotency by binding to genomic DNA.

"In this latest work, they reveal that SON, a protein localized to nuclear speckles, regulates the correct splicing of transcripts encoding pluripotency — regulators such as OCT4, PRDM14, E4F1 and MED24 — ensuring cell survival and maintenance of pluripotency in hESC (and presumably) in human induced pluripotent stem cells as well.”

Prof Eran Meshorer from the Department of Genetics at the Hebrew University of Jerusalem. Prof Meshorer is the 2013 winner of the Sir Zelman Cowen Universities Fund Prize for Medical Research, for his groundbreaking work shedding light on pluripotency.


Abstract
Human embryonic stem cells (hESCs) harbour the ability to undergo lineage-specific differentiation into clinically relevant cell types. Transcription factors and epigenetic modifiers are known to play important roles in the maintenance of pluripotency of hESCs. However, little is known about regulation of pluripotency through splicing. In this study, we identify the spliceosome-associated factor SON as a factor essential for the maintenance of hESCs. Depletion of SON in hESCs results in the loss of pluripotency and cell death. Using genome-wide RNA profiling, we identified transcripts that are regulated by SON. Importantly, we confirmed that SON regulates the proper splicing of transcripts encoding for pluripotency regulators such as OCT4, PRDM14, E4F1 and MED24. Furthermore, we show that SON is bound to these transcripts in vivo. In summary, we connect a splicing-regulatory network for accurate transcript production to the maintenance of pluripotency and self-renewal of hESCs.

Original press release:http://www.a-star.edu.sg/Media/News/Press-Releases/ID/1868/Singapore-scientists-discover-new-RNA-processing-pathway-important-in-human-embryonic-stem-cells.aspx