Testosterone is a hormone which activates the transcription of genes. How does this happen ?
To understand how testosterone activates the transcription of genes, it's important to first understand the concept of gene transcription. Gene transcription is a process by which genetic information encoded in DNA is converted into RNA molecules. This process is essential for the synthesis of proteins, which play crucial roles in the body's structure and function.
Testosterone, as a hormone, binds to specific receptor proteins within the cell. These receptors are known as androgen receptors. When testosterone binds to an androgen receptor, it undergoes a conformational change, forming a hormone-receptor complex.
Once formed, the hormone-receptor complex enters the nucleus of the cell, where it interacts with specific regions of DNA called hormone response elements (HREs) or androgen response elements (AREs). These DNA sequences are usually located near the target genes that testosterone regulates.
The binding of the hormone-receptor complex to these response elements promotes the recruitment of additional proteins called coactivators and corepressors. Coactivators help to enhance the transcriptional activity of the genes, while corepressors can suppress gene transcription.
Together, these coactivators and corepressors modify the local chromatin structure to allow the transcription machinery access to the DNA. This chromatin remodeling allows proteins called transcription factors to bind to the DNA and initiate the process of transcription.
The transcription factors recruit a complex of enzymes called RNA polymerase II, which moves along the DNA strand, synthesizing a complementary RNA molecule from the template DNA strand. This newly synthesized RNA molecule is called messenger RNA (mRNA) because it carries the genetic code from the DNA to the cytoplasm, where it will be translated into a protein.
In summary, testosterone activates the transcription of genes by binding to its receptor, forming a hormone-receptor complex, which then interacts with specific DNA sequences called hormone response elements. This interaction leads to the recruitment of coactivators and corepressors, altering the chromatin structure and allowing the transcription machinery access to the DNA. The transcription factors, along with RNA polymerase II, then initiate the process of gene transcription, resulting in the production of mRNA and the subsequent synthesis of proteins.