A team of cellular biologists from the University of Toronto have discovered how stem cells turn into specialised cells that make up organs. This discovery may help researchers build new organs using stem cells in the future.
The researchers have discovered that the ability of certain proteins to stay near cells was a major factor in determining a stem cell’s state. The presence of proteins would tell the stem cell if it should remain a stem cell or differentiate into a specialised cell.
Researchers had previously discovered that stem cells are regulated by a network of proteins, called transcription factors. Transcription factors are produced from genes within an organism’s DNA and regulate the process by which stem cells determine if they should differentiate or not.
The researchers found that a particular transcription factor named KLF4 gives stem cells their most important properties. The team stumbled upon this discovery as they began looking at how the KLF4 gene is regulated, and then turned their attention to the KLF4 protein.
As lead author Navroop Dhaliwal explains: “Many previous studies focus on the genes that are turned on or off as stem cells are destined to make specific organs,” he continued “Our work exposes a situation earlier in the process where reducing gene expression by 90 per cent does not affect the amount of protein made. It was a really surprising finding when we first saw the results.”
The researchers were first alerted to the potential importance of KLF4 proteins when they discovered that the protein remained functional for a much longer period than other transcription factors. When they looked at the process of stem cell differentiation, they found that KLF4 becomes unstable. By preventing this instability, stem cells could be stopped from differentiating.
As Dr. Dhaliwal explains: “We discovered that the KLF4 protein is highly stable and locks cells in the stem cell state. Breaking it down, however, releases stem cells to specialize and eventually become the different organs of the body.”
The findings may have important implications for regenerative medicine as manipulating KLF4 levels may help scientists change the behaviour of stem cells, encouraging them to regenerate nearby organs.
Source: First events in stem cells becoming specialized cells needed for organ development
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