microRNA is an Important Factor That Propels How We Become a Human
The Picture Shows the Differentiating Mouse Embryonic Stem Cells (green = mesoderm progenitor cells, red = endoderm progenitor cells).
Our human organism is initially starts form an embryo which from one cell to an entire living and breathing body, full of working cells and organs. We never say is too much that embryonic development is a very carefully orchestrated process—everything has to fall into the just place at the right time. Developmental biology and cell biology experts studied this very thing, unraveling the molecular cues that determine how we become human.
There are lot of such experts and studies:
Mark Mercola, Ph.D., professor and director of Sanford-Burnham's Muscle Development and Regeneration Program in the Sanford Children's Health Research Center explains, "The primary step in development is the allocation of cells into three germ layers—ectoderm, mesoderm, and endoderm—that give rise to all tissues and organs in the body".
A study published in the journal of Genes & Development conducted by Mercola and his team discovered that microRNAs, small pieces of genetic material similar to the messenger RNA that carries protein-encoding recipes from a cell's genome out to the protein-building machinery in the cytoplasm, play an important role in this cell- and germ layer-directing process during development. They found the previous junk DNA is actually a treasure.
Why microRNAs were used to be called “junk DNA”? That’s because only microRNAs don't encode proteins. So for many years, scientists dismissed the regions of the genome that encode these small, non-protein coding RNAs as "junk."
Now scientists found microRNA may not encode their own proteins, but they do bind messenger RNA, preventing their encoded proteins from being constructed. In this way, microRNAs are the determinant factor that decides which proteins are produced (or not produced) at a given time. It is both important for normal cellular function and the development of human disease, as well as for embryonic development.
Thus in order to find which layer microRNAs influence in early embryonic development, Mercola and his team individually studied most (about 900) of the microRNAs from the human genome. They tested each microRNA's ability to direct formation of mesoderm and endoderm from embryonic stem cells. They discovered that two microRNA families, let-7 and miR-18 block endoderm formation, while enhancing mesoderm and ectoderm formation. They gained this result by artificially blocking let-7 function and checking to see what happened; by dampening the TGFβ signaling pathway. When these microRNAs tinker with TGFβ activity, they send cells on a certain course—some go on to become bone, others brain.
The findings shown microRNAs are powerful regulators of embryonic cell fate. During this research, researchers combined screening techniques with systems biology that provides a paradigm for whole-genome screening and its use in identifying molecular signals that control complex biological processes.
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