Scientists have recently discovered that cholesterol may help digital development in mice. Usually people believe that Cholesterol is "bad" and causes clogged arteries. A recent study that was published last week researchers believe that the attachment of cholesterol to an important protein controls the development of fingers and toes in mice. Without the cholesterol attaching to the protein mice would develop extra fingers or toes and in the wrong places.
Researchers have named the protein at work is "sonic hedgehog" (yes named after Sonic the Hedgehog video game character). The protein was discovered in 1990 and has proved to have an important role in pattering the development in embryo, including proper digital patterning. An early study showed that mice that do not carry the "sonic hedgehog" only develop a single thumb on the front of the paw or a big toe on the back paw.
The sonic hedgehog protein is produced by a specialized group of cells that are located at the posterior part of the developing limb bud, which in the end develops into a pinkie finger or toe. At the site of development sonic hedgehog concentrations are high. It then diffuses out to the developing limb bud, and the declining concentrations of the protein dictates the identity of the other digits.
The one big mystery scientists are and have been trying to understand is what regulates the sonic hedgehog gradient? The scientists believe it has something to do with that the sonic hedgehog protein has to have cholesterol molecule attached to work properly. The sonic protein is the only protein known to be modified by cholesterol.
Cholesterol is usually found in cell membranes and is believed to "tether" proteins to cells, scientists believe that cholesterol might inhibit the movement of sonic hedgehog throughout the developing tissue. They believe that this might be the reason for the concentrations of proteins were high at the site of the production and then tapered off with distance from the synthesis site.
The researchers are doing extensive experimentation on the mice trying to find out exactly how the sonic hedgehog travels throughout the mice to the synthesis site. They are doing research on mice that would only have half of their sonic hedgehog protein could attach to cholesterol these mice have developed normal digits 2 through 5, but did have duplication of these digits anteriorly. The findings suggested that Sonic hedgehog without cholesterol traveled further than normal, triggering the anomalous digit duplications.
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Researchers have named the protein at work is "sonic hedgehog" (yes named after Sonic the Hedgehog video game character). The protein was discovered in 1990 and has proved to have an important role in pattering the development in embryo, including proper digital patterning. An early study showed that mice that do not carry the "sonic hedgehog" only develop a single thumb on the front of the paw or a big toe on the back paw.
The sonic hedgehog protein is produced by a specialized group of cells that are located at the posterior part of the developing limb bud, which in the end develops into a pinkie finger or toe. At the site of development sonic hedgehog concentrations are high. It then diffuses out to the developing limb bud, and the declining concentrations of the protein dictates the identity of the other digits.
The one big mystery scientists are and have been trying to understand is what regulates the sonic hedgehog gradient? The scientists believe it has something to do with that the sonic hedgehog protein has to have cholesterol molecule attached to work properly. The sonic protein is the only protein known to be modified by cholesterol.
Cholesterol is usually found in cell membranes and is believed to "tether" proteins to cells, scientists believe that cholesterol might inhibit the movement of sonic hedgehog throughout the developing tissue. They believe that this might be the reason for the concentrations of proteins were high at the site of the production and then tapered off with distance from the synthesis site.
The researchers are doing extensive experimentation on the mice trying to find out exactly how the sonic hedgehog travels throughout the mice to the synthesis site. They are doing research on mice that would only have half of their sonic hedgehog protein could attach to cholesterol these mice have developed normal digits 2 through 5, but did have duplication of these digits anteriorly. The findings suggested that Sonic hedgehog without cholesterol traveled further than normal, triggering the anomalous digit duplications.
“We found that, without cholesterol, Sonic hedgehog moves more readily, far from its site of synthesis, all the way to the anterior part of the limb bud where it is normally never detected,” Chiang explained.
When Sonic hedgehog travels to tissue where it normally would be absent and missing the cholesterol, extra digits may form, which is a condition known as polydactyly. Although, the causes of polydactyly in humans are not completely understood, mutations in some part of the Sonic hedgehog signaling pathway are on the list of suspects.
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