Genes & Cells

MicroRNA treatment mends broken hearts
When it comes to the heart, some old cells can become new again, especially with some prodding. Scientists have known that the heart can regenerate some of its cells, but there has been debate about the exact source of the new cells — whether it’s other heart muscle cells, stem cells or even cells from the heart’s outer lining. Researchers at Harvard Medical School and colleagues analyzed the atomic composition of molecules in newly generated mouse heart muscle cells and determined that the newborn cells come from neighboring old heart muscle cells. In a separate study, a research team reports on a way to spur new heart cell growth. Two microRNAs, small genetic molecules that help control protein production, can stimulate adult heart cells to replicate, Mauro Giacca of the International Center for Genetic Engineering in Trieste, Italy, and colleagues report. Mice given the microRNAs after a heart attack made a nearly full recovery, the team found. Harnessing the heart’s own regenerative ability may one day help heal heart attack damage in people. Both studies appear online December 5 in Nature.

Gypsies’ genes tell migratory tales
A new DNA analysis reveals the wanderings of the Romani, Europe’s largest minority group, and indicates that the group originated in northern India about 1,500 years ago. About 47 percent of the original population of Romani, also known as Gypsies, then moved west, mixing with people in the Middle East, Central Asia and Caucasus on their way to the Balkans. About 900 years ago, small groups of Romani left the Balkans and headed for other parts of Europe, the evidence suggests. More recent mixing with outsiders shows up to different degrees among Romani in various European countries, reflecting cultural attitudes about the group, a European consortium of researchers reports online December 6 in Current Biology. The DNA data back up archaeological, historical and linguistic data.

Insulin and obesity linked, but how?
A new study may flip the tenet that getting fat causes the body’s insulin levels to go out of whack. Obesity is a well-known risk factor for developing type 2 diabetes, a disease in which body cells stop responding to insulin, causing blood sugar to rise. The pancreas responds by making more insulin until it gives out. Researchers from the University of British Columbia in Vancouver discovered that reducing insulin production protected mice from gaining weight on a high-fat diet by turning energy-storing white fat into energy-burning brown fat. High levels of insulin were associated with inflammation and overstuffed white fat cells, two hallmarks of obesity, the team reports in the Dec. 5 Cell Metabolism. The findings indicate that manipulating insulin levels might help prevent obesity and its associated health problems, including diabetes.