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- Parent Category: Microbiology
- Category: Medical
by Monya Baker
An RNAi screen finds a protein complex that keeps pluripotency genes open for transcription
In efforts to piece together the network that maintains pluripotency, one strategy is to remove potential components and see if pluripotency is disrupted. Researchers led by Frank Buchholz of the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden, Germany, knocked down thousands of genes one by one and found evidence that embryonic stem cells have specialized gene-transcription machinery. Buchholz's team set up a screen so that they could identify whether levels of a key pluripotency protein, Oct4, dropped in the presence of a series of over 25,000 short RNA molecules (which could be mapped to approximately 15,000 annotated genes). This screen identified hundreds of genes, so the researchers focused on the ones that reproducibly made Oct4 levels drop the most dramatically, and they decreased this number to a set of 16 genes.
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- Parent Category: Microbiology
- Category: News
by Monica Baker
MicroRNAs, along with transcription factors, produce homogenous iPS cell colonies from mouse fibroblasts
For the first time, microRNAs have been used to facilitate reprogramming. MicroRNAs — short stretches of nucleotides that can suppress translation of certain genes — are one of several strategies being pursued in the search for the best techniques to create induced pluripotent stem cells, a type of cell that behaves like embryonic stem cells but isn't derived from embryos and has vast implications for cell therapy, drug discovery and disease modelling. So far, all techniques to reprogram cells have required the insertion of pluripotency genes, which either directly alters a cell's DNA or creates the potential for the alteration to occur. Recently, several labs have made headway using small molecules instead of genes1. Now a team led by Robert Blelloch at the University of California, San Francisco shows that microRNAs are another potential tool for reprogramming without gene insertion2.
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- Parent Category: Microbiology
- Category: Research
Monya Baker
A new zinc finger protein, perhaps the first of many, silences integrated viruses
When induced pluripotent stem cells were first made, keen-eyed researchers rejoiced that the viruses required to reprogram the cells did not need to stay active indefinitely. As the cells reprogram, the viruses are silenced. That opened the door to reprogramming cells without genetic engineering, which meant that the resultant cells would be more applicable to drug screening and cell therapies.
Read more: Embryonic Stem Cells Have Their Own Way to Deal With Viruses
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- Parent Category: Microbiology
- Category: News
Monya Baker
Strategies for moving embryonic stem cells toward pancreatic or blood cells
Embryonic stem cells are, for most scientists, a means to an end. The cells themselves matter less than the cells they can produce, but making them differentiate into the desired quantities of particular cell types is easier said than done. That is especially true for tissues of the two inner germ layers, the endoderm (which forms most glands) and the mesoderm (which forms the muscles and cardiovascular system). Now, two new protocols promise more efficient ways to generate these tissues from embryonic stem cells.
Read more: Efficient ES Cell Differentiation : The Right Tweak at The Right TIme
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- Parent Category: Microbiology
- Category: Research
Monya Baker
Six reprogramming factors in a plasmid reach a holy grail
For the first time, human skin cells have been reprogrammed to pluripotency without requiring genetic elements to insert themselves into the reprogrammed cells. Though so-called induced pluripotent stem cells promise to be as powerful as embryonic stem cells in their ability to differentiate into all cell types, standard techniques use viruses to insert multiple copies of reprogramming genes into the cells; this makes the cells less predictable, and it creates a higher risk of a cancerous growth. As a result, many laboratories have been racing to publish techniques to reprogram cells without permanent genetic modification.
Read more: Look Now! Human iPS Cells With No Genetic Integration
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- Parent Category: Microbiology
- Category: Medical
Monya Baker
Electron microscopy reveals functioning synapses
[Editor's note: It's not easy to assess a study's ramifications from press releases, three of which caught my eye this month. I asked Phil Schwartz, a neural stem cell expert at Children's Hospital of Orange County, California, to help me understand the gap between study and therapy. I also asked authors from each paper to respond. This article is one of three resulting from this process.]
Research summary by Nature Reports Stem Cells: For many types of cell therapy, getting transplanted cells to integrate into a patient's tissue will be harder than making the cells. Researchers led by Leyan Xu of Johns Hopkins Medical Institutions, in Baltimore, Maryland had previously shown that grafts of human neural stem cells (NSCs) could relieve symptoms in a rat model of amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease).
Read more: Human Interneurons Engraft in a Rat Model of Lou Gehrig's Disease