A study conducted at KU Leuven, Belgium, and published in the journal, Cell Metabolism, reveals that genetically modified mice have introduced an unexpected variable in roughly 250 diabetes research studies.
Genetically engineered mice are commonly used to study human diseases and are very important tools in medical research. A transgene, an external gene related to a disease, is inserted in mice DNA genome, and in order to improve the transgene expression, this may be inserted together with the human growth hormone (hGH) gene, which is not expected to be expressed in genetically modified mice. However, the authors of the study, entitled “Impaired Islet Function in Commonly Used Transgenic Mouse Lines due to Human Growth Hormone Minigene Expression,“ found that is not the case.
They realized that these mice showed pregnancy-like signs due to the expression of low levels of hGH. In fact, similarly to what happens during pregnancy, this hormone binds to prolactin receptors on β cells. As a result, pregnancy-like changes are induced in gene expression, along with increased insulin levels, which are normally affected in diabetes. This raises serious concerns in diabetes research as insulin levels might have been affected by hGH, and not by any other studied gene. Results published with these mice may need to be reinterpreted. “Meanwhile, there are genetically modified mice available today that do not include the human growth hormone. These mice can be used to reinterpret previous results,” says John Creemers, one of the researchers behind the study.
“We have to continue verifying our methods with a critical eye, even if it means that research advances at a slower pace. For diabetes research, this unexpected turn is an important step forward. Now that the haze around the artificial growth hormone has been cleared, scientists can plan future research with a clear vision,” reminds Frans Schuit, who co-supervised the study.
In other news on developments in diabetes research, a recent study, titled, “Night-shift work and incident diabetes among African-American women,” published in Diabetologia by Dr. Varsha Vimalanda and colleagues in Boston shows a positive association between night shift work and type 2 diabetes among African-American women. The data now obtained by the Black Women’s Health Study (BWHS) confirms previous diabetes research on both white nurses in the USA and Swedish women.