SMAD3 - major protein in male puberty, key finding of a study. Puberty development in boys is associated with SMAD3 protein and the rate at which it is produced.
Researchers, Kate Loveland and Catherine Itman from the Faculty of Medicine, Nursing and Health Sciences have discovered through laboratory testing that half as much SMAD3 protein results in faster maturation than the norm, and an inability to create SMAD3 results in abnormal responses to testosterone.
"SMAD3 is a protein that translates signals from the environment outside the cell to the nucleus, where it switches genes on or off. We have been investigating how SMAD3 influences the growth of testis cells and their ability to respond to testosterone," said Itman.
On the other hand, puberty is delayed when testis cells cannot respond normally to testosterone.
Testosterone acts through specialized cells in the testis called Sertoli cells. Before puberty, Sertoli cells multiply, allowing the testis to grow. At puberty, Sertoli cells must stop growing so they can support sperm precursor cells to develop into sperm.
The researchers have been investigating how Sertoli cells switch from a multiplying state, making the testis big enough to make sperm, to a mature state that sustains sperm production.
"We have discovered that this is not an "on-off" switch. Rather, it is the amount of the SMAD3 protein in the Sertoli cell that is different in the immature, multiplying Sertoli cell compared to the mature, adult cell," said the researchers.
The research identified that it is the amount of SMAD3 present that controls Sertoli cell activity prior to, or after, puberty. When SMAD3 levels are reduced, sperm develop earlier. When SMAD3 is absent, Sertoli cells take longer to respond to testosterone.
"We hope that through our research, we will inform decisions about the influence of chemicals in our environment on the timing of puberty in boys and on the fertility of adult men" said Itman.
The findings have been published in the international biomedical journal Endocrinology.