Activin is a type of protein that plays a key role in the human reproductive system. It aids in the release and conversion activities of follicle stimulating hormone (FSH), the hormone responsible for growth, puberty, development and reproductive processes. Additionally, activin is important in the control and coordination of the female menstrual cycle. It also is involved in other secondary processes throughout the body.
This complex protein works differently in the male and female reproductive systems. In females, it works in the follicles of the ovary to stimulate FSH secretion and biosynthesis. Biosynthesis is the process by which FSH is changed into a more complex biological product. When luteinizing hormone is active before ovulation, activin supports its function. In males, it encourages sperm division and supports testosterone production.
Classified as a beta protein, activin is produced in the placenta, the pituitary gland, the testes or ovaries, the skin and other organs. It is found in damaged skin and is thought to encourage the development of scars to assist in the healing process. By stimulating the release of keratinocytes, activin aids in wound healing, skin growth and skin shaping. When activating fibroblast cells, it works to synthesize collagen and repair connective tissue.
Morphogenesis, or shape development, of a number of organs is controlled by activin. These organs include the lungs, prostate and the kidneys. Special protein receptors called type I and II transmembrane kinase receptors detect the signals released by activin and act according to their location and function.
A number of possible roles for activin have been studied in the scientific community. This protein complex might have far more significance in the human body than was once thought. Some of the suggested functions are control over the growth and spreading of cancer cells, regulation of the reproduction and specialization of embryonic cells, higher order brain functions and maintenance of hormone levels in areas outside the reproductive system.
The importance of this protein complex is made evident when it is lacking during fetal development. An insufficient amount can lead to defects in the neural tube and other developmental defects. The type of defect and its severity depend on the area in which the protein is lacking and the stage of development in utero. Activin might also be involved in the development of a number of diseases, and targeting the signaling phase of the protein might be a way to treat certain pathologies.