In This Issue... June 21, 2012

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Cool Image: Double-Duty Cell Cycle Protein

Jean Cook • University of North Carolina School of Medicine

This normal cell is undergoing the third phase of cell division, when copied chromosomes align in the middle of the spindle. Chromosome attachments are shown in green, and microtubules are shown in red. The protein Cdt1 helps maintain a stable structure. Scientists previously thought that Cdt1 was only busy during DNA replication, loading proteins onto strands of DNA before they're copied. It now appears that Cdt1 helps another protein, Hec1, to distribute chromosomes evenly between dividing cells. Mistakes in cell division can lead to birth defects and diseases such as cancer, so this discovery could point to novel therapies. Read more...

This work also was supported by NIH's National Cancer Institute.

How Two Proteins Help Convert Carbs into Energy

Jared Rutter • University of Utah

When you consume carbohydrates, your body converts them into pyruvate, which your cells' mitochondria use to produce energy. If that process goes awry, deadly consequences can occur. Researchers have discovered that two proteins, Mpc1 and Mpc2, play a vital role in the process. The proteins gather in the mitochondrial membrane to help pyruvate through. From there, mitochondria can convert pyruvate into energy for cells. The scientists also learned that impaired Mpc1 and Mpc2 can cause a deadly yet unnamed neuromuscular disorder. Increased knowledge of the proteins' function could improve our understanding of the disorder, as well as cancer and heart disease, which are also associated with abnormal energy production. Read more...

This work also was supported by NIH's National Institute of Diabetes and Digestive and Kidney Diseases.

Caption: The mitochondrion (pictured) acts as a cell's power plant, turning sugars into energy. Credit: National Science Foundation.

Researchers Determine the Cellular Benefits of Omega-3s

Edward Dennis • University of California, San Diego

Dating back to at least the 1950s, cod liver oil has been touted for helping to treat eczema and arthritis. Its active ingredient—an omega-3 fatty acid—has also been associated with improved heart health. Researchers have just begun to understand the cellular mechanisms behind omega-3s. These fatty acids-including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)—inhibit the enzyme cyclooxygenase, which produces hormones that spark inflammation. Since chronic inflammation is the hallmark of diseases such as atherosclerosis and rheumatoid arthritis, this advance could lead to therapies with widespread applications. Read more...

Caption: Omega-3 fatty acids—like those found in fish oil caplets—may control inflammation associated with diabetes, cancer and other diseases. Credit: Wikimedia Commons.

Stem Cell Suicide Prevents Harm to Embryo

Mohanish Deshmukh • University of North Carolina at Chapel Hill

Before an embryo's stem cells become heart, skin or other cell types, they have a very important job to do: nip DNA damage in the bud. If exposed to chemicals, radiation or viruses that could harm the embryo, the stem cells quickly kill themselves. They do this with the help of the Bax protein, which interacts with other proteins to shut down the cells. Unlike most cells, the embryonic stem cells pre-activate Bax, so that the protein is ready at a moment's notice. Interestingly, to prevent accidental cell suicide, the cells store this pre-activated Bax in the Golgi apparatus. This new understanding could aid the development of stem cell therapies. Read more...

Caption: Embryonic stem cells store pre-activated Bax (red) in the Golgi, near the nucleus (blue). Credit: Mohanish Deshmukh. High res. image (JPG, 87KB)

New Details about Cholesterol's Role in Alzheimer's Disease

Charles Sanders • Vanderbilt University Medical Center

While scientists know that a protein called amyloid-beta (and its precursor, abbreviated APP) is somehow linked to Alzheimer's disease, recent studies have implicated a co-conspirator: cholesterol. Now, using laboratory-made membranes and other techniques, researchers may have determined how the two molecules work together. The scientists propose that cholesterol binds to APP and then coaxes it to sections of the cell membrane called lipid rafts. There, other molecules cut off pieces of APP, transforming it into amyloid-beta, which builds up as plaque in the brains of people with Alzheimer's. A drug that blocks cholesterol from interacting with APP might help prevent the memory-depleting disease. Read more...

Caption: Researchers studying Alzheimer's disease propose that cholesterol (black, white and red) binds to the amyloid precursor protein (green and blue), which is known to be involved in the disease. Credit: Charles Sanders. High res. image (JPG, 49KB)