PTC stands for Post Transcriptional Control. Post-transcriptional control mechanisms are all the regulatory events that take place after a messenger RNA (mRNA) molecule is copied from DNA (i.e., after the transcription process). These mechanisms include the decoding of the mRNA molecule so that a protein is synthesized, the determination of how efficiently an mRNA is utilized to make protein, and how long an mRNA lasts in a cell. All of these regulatory effects have a direct impact on how much protein is produced from each mRNA.
Proteins are present in all living beings and are essential for the life of each cell as well as for the life of the entire organism. To produce proteins, organisms use information encoded in their genes. Genes consist of discrete stretches of DNA molecules located within chromosomes in the nucleus of a cell. Not all of the genes in an organism are used, or expressed, at once. To express a gene and create a protein, the cell follows an ordered, multi-step process.
The first major step in the process of gene expression is called transcription. During transcription, the cell copies the information from a gene into an intermediate form, ultimately creating mRNA molecules. Each mRNA molecule is specific to a particular gene and exists in the cell only for the period it is needed. When no longer needed, the mRNA molecule is degraded and eliminated from the cell.
When present in the cell, the mRNA is used in the next major step of gene expression, called translation. During translation, a specialized cellular apparatus, called the ribosome, decodes the information in the mRNA molecules to produce individual proteins. The quantity of a particular protein synthesized in a given time depends both on how much of the mRNA that codes for that protein is in the cell and on how efficiently the cellular translation apparatus uses that mRNA.
Post-transcriptional control processes are the events that occur from the time that the mRNA has been transcribed from the DNA continuing through to the production of proteins and the eventual degradation of the mRNA. Post-transcriptional control processes modulate how long an mRNA molecule lasts in the cell and how efficiently it is used to make its protein. Precise control of mRNA utilization is critical for many important functions, including the cell division cycle, the immune response, and the growth and repair of tissues.
PTC's approach is to discover and develop small molecule drugs that affect (inhibiting or enhancing) protein production by targeting post-transcriptional control mechanisms.
PTC's approach connects the significant therapeutic opportunity of this important area of biology with the advantages of small-molecule compounds. PTC believes that small molecules that interact with components of the post-transcriptional control apparatus can effectively regulate protein levels, either by inducing or enhancing the production of a needed protein or by blocking the production of an undesirable protein.
PTC’s discovery efforts target post-transcriptional control processes: the sequence of events in the cell that ultimately regulate the rate and timing of protein production as indicated by the yellow path.
Small molecules that target post-transcriptional control to either up- or down-regulate protein production may have the potential to treat a wide variety of diseases, including those such as genetic disorders, cancer, anemia, and inflammation that can result from the body's production of too much or too little of a particular protein. Targeting post-transcriptional control processes with small molecules may also be applicable to treating infectious diseases, including viral infections, in which a virus acts by harnessing the infected body's post-transcriptional control processes, and bacterial infections, in which the bacteria have their own distinct post-transcriptional control processes.
There are several marketed drugs that act by affecting post-transcriptional control processes. These drugs include the aminoglycoside antibiotics, such as gentamicin, other antibiotics, including erythromycin and linezolid, and some immunosuppressant drugs, such as rapamycin. Although the majority of these drugs were developed without prior knowledge of their mechanism of action, PTC believes that the manner in which they act validates the potential of PTC's scientific approach. PTC believes that a methodical and scientific approach to the identification and selection of post-transcriptional control process drug targets has significant commercial potential.