How does genetic engineering work?

Using bacterial plasmids, we can transfect an organism’s DNA with any gene that we want them to express.  The gene does not necessarily have to be from the same species.  Then the gene can be expressed in the genetically modified organism!  Gene expression is the production of a protein that the gene encodes.

How do particular genes get turned on?

There are many ways to control gene expression, but in this case, a protein receptor is activated, which then activates a G-protein, which activates a chain of reactions inside the cell.  This leads to activation of a transcription factor, which is a molecule that causes a particular sequence of DNA to be transcribed into RNA and then translated into a protein.

How can we test these G-protein regulated pathways?

If we administer or block particular molecules that may be part of the pathway, this should elevate or inhibit the end result of the pathway.  Then we can figure out which molecules play a role in the pathway and which ones do not.

What is optogenetics?

Optogenetics is the use of light-sensitive proteins to control gene expression.  Many light-sensitive proteins exist that can be used in optogenetics, and melanopsin is just one of them.  When these proteins are exposed to light in an organism it can turn a gene on or off (almost like a light switch!) so that protein production can be finely controlled.

What is melanopsin?

Melanopsin is part of a group of proteins called opsins.  It is found in organisms such as frogs, mice, and humans. Opsins are light sensitive protein receptors that respond to different wavelengths of light and cause cellular changes.  Melanopsin in particular plays a role in regulating the circadian rhythm, but not in vision.  In frogs, it causes a change in pigmentation of the skin based on exposure to light.

How can we use genetic engineering for therapeutic purposes?

One way to use this technology to produce therapeutic proteins is to transform cultured cells to have them produce proteins in a bioreactor.  These proteins can then be harvested and administered to patients that need them.  Another way to use this technology is to genetically modify the organism that has a protein deficiency.  For example someone with type 1 diabetes could benefit from a genetic modification of their own DNA to allow them to produce their own insulin.