How Sonic Hedgehog Controls Your Brain

Posted Mar 10, 2009

You may know him as the blue hedgehog created by SEGA that can run at lightning speeds, but science experts know Sonic hedgehog as a protein in the Hedgehog signaling pathway.  As a matter of fact, the Sonic hedgehog protein is very important during early development for humans.  The Sonic hedgehog protein controls the division of adult stem cells in the brain.  The Sonic hedgehog homolog (SHH) protein is often times implicated in the development of carcinogenesis, when normal cells are transformed into cancer cells.

The Sonic hedgehog gene was discovered by Eric Wieschaus and Christiane Nusslein-Volhard in 1978.  They won the Nobel Prize for this in 1995 along with Edward B. Lewis.  Lewis noticed how the Sonic hedgehog gene caused a fruit fly to grow cuticles on its embryo, similar to how a hedgehog has spikes.

When humans are developing, the brain is organized in groups of neurons.  These groups of neurons are called brain nuclei and each have specific functions.  How the brain nuclei takes size, shape, and location is ambiguous but the Sonic hedgehog protein is essential for part of the development.  The Sonic hedgehog is also known as a “positioning signal” that coordinates the brain nuclei process.

“A positional signal is a neat mechanism for creating patterns of different types of cells,” stated Cliff Ragsdale, Ph.D. and Chair at the University of Chicago Neurobiology department in an interview with ScienceDaily several years ago.  “Target cells respond differently to a signaling molecule according to their distance from the source of the signal.”

The Sonic Hedgehog protein kicks in around midbrain development.  Ragsdale’s group at University of Chicago has been studying the midbrain for quite some time because the formation of the brain around that period is very organized in cell columns.  Each cell column has molecular identities.

The experiment that Ragsdale’s group conducted several years ago sounds quite riveting.  They took the protein and injected it into 2 day old embryo chicks.  Three days later, they examined the chicks and found that all of the midbrain arcs were present.  They delivered the genes using electroportation into an area that never sees it.  There was a complete duplication of midbrain arcs that was created after the gene was implanted.

A couple of years ago, the New York Times put together an article about how giving medical conditions “cute names” like Sonic may not be funny to the patients that actually have problems related to those names.

?It?s a cute name when you have stupid flies and you call it a ?turnip,? ? stated Dr. Chris Doe, a Biology professor specializing in fruit fly genetics at the University of Oregon.  “When it?s linked to development in humans, it?s not so cute any more.?

Is it OK to give the names of medical conditions and cranial proteins the name of characters and funny terms in pop culture? Or is it a mockery? Let me know in the comments.

[References from: ScienceDaily/Wikipedia/NYT]