Novel Potential Role for Vitamin D During Puberty
Vitamin D plays an important role in many aspects of human health and development. The so-called “sunshine” vitamin is perhaps best known for its role in keeping bones strong, but it may also help with immunity and reduce the risk of some diseases. Now, researchers in the Department of Human Health and Nutritional Sciences have found evidence of a new potential function for the super vitamin: influencing the growth of mammary glands during puberty.
The team, led by Prof. Kelly Meckling, made the discovery when they uncovered a novel vitamin D receptor – named MARRS or Erp57 – in the mammary gland of mice. Traditionally, vitamin D was believed to have just one fate after it entered the cell, which was to bind to the vitamin D receptor (VDR), but there is growing evidence that it can also bind to MARRS.
“Research on vitamin D binding to the MARRS receptor is still new and some experts still aren’t convinced that vitamin D binds to anything other than the VDR,” says PhD candidate and lead author Allison Wilkin.
The research team bred three strains of mice with different quantities of MARRS receptors in their mammary glands: normal, intermediate and none. They then extracted the glands when the mice reached puberty and measured the gland’s growth. Compared to mice with a normal amount of MARRS receptors, mice with partial or complete removal of MARRS receptors had significantly reduced mammary growth.
“Our research didn’t directly test vitamin D on mammary gland growth, but it did show that the MARRS receptor was involved in this process, and we know that vitamin D binds to the MARRS receptor in other tissues,” says Wilkin.
Based on their results, the research team speculates that MARRS functions differently than the VDR, despite the fact that both receptors are activated by vitamin D. In many cells VDR activation reduces growth, which is why vitamin D is believed to help reduce cancer risk. But Wilkin’s results suggest that vitamin D can also promote cell growth when it binds to MARRS.
Other laboratories have studied the relationship between increased mammary gland growth rate during puberty and breast cancer risk later in life. Since MARRS promoted cell growth, Wilkin speculated that vitamin D intake and VDR/MARRS activation could potentially be a factor in the relationship between mammary gland growth and breast cancer risk.
The project has laid the groundwork for additional work to untangle the complex links between vitamin D and normal development and health. Wilkin and Meckling will next make a direct examination of the interaction between vitamin D and the MARRS receptor in developing mammary glands over multiple time points. Ultimately, their goal is to figure out the full role of the MARRS receptor and vitamin D early in life.
“We know that vitamin D requirements increase later in life to an extent, but we don’t yet know how important it is during growth and development,” says Wilkin.
Funding for this project was provided by Natural Sciences and Engineering Research Council of Canada.
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