http://www.dnaindia.com/dnaprint910.php?newsid=1404338

Scientists have identified a gene that seems to be a master regulator of human brain development. The human brain is a marvel of nature with more than 100 billion neurons and billions of other specialised cells.

A team of scientists from the University of Wisconsin-Madison (UWM) have identified a gene - known as Pax6 - which guides undifferentiated stem cells to tightly defined pathways in becoming different types of cells in the brain.

The new finding is important because it reveals the main genetic factor responsible for instructing cells at the earliest stages of embryonic development to become the cells of the brain and spinal cord.

Identifying the gene is the first critical step towards routinely forging customised brain cells in the lab.

Moreover, the work contrasts with findings from animal models such as mouse and zebra-fish, pillars of developmental biology and thus helps cement the importance of the models being developed from human embryonic stem cells.

The new work reveals the pervasive influence of the gene on the neuroectoderm, a structure that arises early in embryonic development.

It also churns out the two primary forms of brain cells - neurons and glial cells - and the hundreds of cell subtypes that make up the human brain.

"This is a well-known gene. It's been known for a long time from work in mice and other animals, but what Pax6 does in human development isn't very well known," says Su-Chun Zhang, professor of anatomy in the UWM School of Medicine and Pubic Health.

In animals, the gene is known to play a role in the development of the eye and is seen in some neural cells.

In the human cells used in the new Wisconsin study, Pax6 was observed in virtually all the cells of the neuroectoderm.

"The fact that Pax6 is uniformly expressed in all human neuroectoderm cells was a surprise. This is a phenomenon that is a departure from what we see in animals. It seems that in the earliest stages of development, human cells are regulated by different processes," Zhang explains.

The finding may help explain why the human brain is larger and, in many respects, more advanced than what is observed in other species, said a university release.

"In a way, it makes sense that the human brain is regulated in a different way. The brain distinguishes humans as a unique species," Zhang added.

These findings appeared in the Thursday edition of Cell Stem Cell.

July 2, 2010 (Daily News & Analysis)