A gene is basically a one dimension sequence of nucleotides that signals for the production of a protein. (Reynaud, 2010) The protein itself is merely a sequence of amino acids arranged in a specific manner. The sequence of the gene is linear and so is the sequence of the protein. DNA, which is a common term heard now and then is merely a collective term for all the genes of the body. The mechanism by which genes on the DNA work its action and are expressed in the body is known as translation. (Reynaud, 2010) Through translation, the genes come out as proteins and thus do specific actions in the body. The amino acid sequence mentioned earlier basically is a blue print that tells how the protein is going to be made and what specific function it will do.
The genetic material that we have is present in every single cell of the body. Regardless of which cell it is, the DNA and the genes are always present t in it. The proteins that the gens make carry out the required acts that a person needs to do in order to live and grow. Along with the bodily functions and actions, it is genes that that determine how we look, the way we act and how are body functions two. Even a little kid knows that he got half his genes from the mother and half from the father. However, it is not only looks that our mother and father decide. Their genes and consequently our genes also decide whether all the functions in our body will be normal or not. Some errors or defects in a genetic sequence can carry on for generations and thus give rise to inherited diseases. A mutation in the simplest forms is an n error or a defect in the genetic sequence of a person. Some mutations may go unnoticed and not produce any harmful effects. On the other hand, mutations may alter the production of certain proteins that go on to affect our body negatively. These negative effects then cumulate and present in the form of inherited disorders that are so common.
Age and Age related diseases have been linked to the declining function of the mitochondria of cells in the body. Aging is a natural process and the senescence has been linked to processes like DNA methylation, telomerase shortening and the lastly the damage done by reactive oxygen species made by the mitochondria. (Schapira, 2012) The mitochondrial dysfunction can lead to production of ROS that damages cells like the neurons in Substantia Niagara in the brain and lead to diseases like Parkinson's. Also, the mitochondrial dysfunction causes the production and further accumulation of abnormally folded proteins that causes more degeneration. These effects are observed in other organs and systems and cause disease like Alzheimer's and diabetes as well. With the ongoing research on the link between mitochondrial DNA mutations and degenerative disorders, much is being done to figure out diagnosis, treatment and prevention of disorders like Parkinson's disease.
Protein Folding Diseases
The information required for proteins to fold correctly resides in the amino acid sequence. According to Levinthals Paradox, the proteins fold very fast into their most stable form because all the amino acids interact locally. (Reynaud, 2010) These interactions and the limited space thus make the proteins fold into the proper format. The proteins that have a difficult time folding into their native state, take help from chaperone molecules that make sure that the proper format is achieved. Ron Lackey mentioned the term chaperone when he found out that nucleoplasmin is bale to bind to histones and thus ensure the interaction between histones and DNA doesn't go haywire. That is to say that nuceloplasmin functioned as a chaperone and thus ensures that no inappropriate interactions take place. (Reynaud, 2010) The chaperones are necessary in some instances so the proteins don't go away from their native state and thus alter their own three dimensional structure. The three dimensional structure is crucial in determining how a protein will at in the body.
For most of the proteins, the most apparent structural motif is the structural confirmation that is popular as alpha helix. Whenever a protein misfolds or in simpler terms becomes toxic, it takes on the beta form. Misfolding basically occurs when a protein goes about a different pathway for folding or it follows an energy minimizing funnel. (Reynaud 2010) The toxic or the misfiled form of the protein then goes on to interact with the normal proteins and make them turn into a toxic state. That is when the proteins become infectious and are known as a prion. These prions are known as infectious because neither are they detected by the cells protective mechanisms nor removed by ultra violet radiation.
Protein misfolding and the way it is incorporated into membranes is an important factor in causing diseases. There are many diseases that are due to mutation in the a1 anti-trypsin and neuroserpin that give rise to protein misfolding. (Appella & Johansson, 2011) So why exactly is protein folding a bad thing? Surely proteins go on to carry important functions and one might say that if they're misfiled, they just won't do the function. The deposition of proteins in abnormal places can give rise to derangements in the normal functioning of the body. A common type of prion is one that is filled with beta pleated sheets and can give rise to amyloids that can be very harmful for the body. (Norrby 2011) Prion related disorders were proven when a prion infected protein rich food was used to feed the cattle. This led to a pandemic of bovine spongiform brain disorder which was acquired when anyone consumed the infected meat. (Norrby 2011) The amyloid formation that is created by protein misfolding gives rise to many diseases like type 2 diabetes and Alzheimer's disease. (Appella & Johansson, 2011) Many studies and reviews have been done to highlight how the protein aggregation and deposition is all because of misfolding. T The deposition is harmful and so is the interaction that the misfiled proteins go on to have with the membrane of different cells in the body. (Appella & Johansson, 2011)
A lot of the neurodegenerative diseases known are known to be because of abnormal accumulation of portion aggregates. It is seen that when these proteins deposits, brain function gets damaged at a cellular and at the synapse level as well. A suggestion that is sent forward is that increased stress on the endoplasmic reticulum of a cell is a leading cause of dysfunction in the long run. (Matus, Glimcher & Hetz, 2011)
There is still a lot of uncertainty in determining what the reason for protein misfolding is. One speculation is that sometimes same sort of protein chains known as homologous proteins are present in the body with a set blueprint on how exactly they will fold. When one of the protein folds, the other proteins similar to it fold in the same manner and thus make aggregates that have detrimental effects. (Norrby 2011) The aforementioned mechanism has thought to be one of the leading causes of degenerative disorders. A second speculation could be that certain amino acids are prone to being pathogenic. The amino acids are present in a sequence that can lead to them misfolding and thus producing diseases.
How exactly did the idea about protein causes diseases come out forward? The Creutzfeldt-Jakob disease was discovered by two German neurpathologists in 1920s. (Norrby 2011) This disease is characterized by slow destruction of the neural tissue known as spongiform encephalopathy. The incidence of this disease kept increasing yet no one knows what exactly caused the disease. More than 80% of the cases of this disease were sporadic and only ten percent were familial. (Norrby 2011)
There were many links seen between CJD, scrapies in sheep and Kuru in the Stone Age Fore people. Kuru was a serious neurological disease that was said to be caused by an infectious agent. A major route of infection of this disease was due to the ritual of cannibalism that was taken by the Fore people. When someone died, their body would be taken for the funeral meal and the women and children for the brain. The central nervous system had the biggest concentration of this disease thus it spread to women and children. CJD was a more established and reformed form of Kuru but the cause still could not be found. In the 1970s when Gajdusek examined the brain tissue of infected hamster, he tried to isolate what the causing mechanism was. The scientist initially thought it to be virus yet the results revealed something more pure. (Norrby 2011) Since he could not discover any nucleic acid, he went on to name it a prion. This word was an amalgamation of both an infectious and a protein like agent. Further studies into the agent gave the discovery that this protein was created by a gene…