"Scientists have known that Bmi1 is a central control switch within the adult stem cells of many tissues, including the brain, blood, lung and mammary gland,” said Ophir Klein, MD, PhD, who directs the Craniofacial and Mesenchymal Biology (CMB) Program and serves as chair of the Division of Craniofacial Anomalies at UCSF. “Bmi1 also is a cancer-causing gene that becomes reactivated in cancer cells.”
In the current study, postdoctoral fellows Brian Biehs, PhD, and Jimmy Hu, PhD, determined that there is a group of adult stem cells at the base of the growing mouse incisor and that these stem cells possess active BMI1. They showed that BMI1 can suppress a set of genes called Hox genes that, when activated, trigger the development of specific cell types and body structures. In the mouse incisor, the researchers showed that activity of BMI1 in the stem cells maintains their stem cell fate and prevents inappropriate cell differentiation by suppressing the expression of Hox genes.