ROS are required for mouse spermatogonial stem cell self-renewal

Area of Science:

• Reproductive biology
• Stem cell research
• Cell signaling

Background:

• Reactive oxygen species (ROS) are generally considered harmful to spermatogenesis and spermatogonial stem cells (SSCs).
• However, the precise role of ROS in SSC self-renewal remains debated, with some evidence suggesting involvement in stem cell maintenance in other tissues.

Purpose of the Study:

• To investigate the role of ROS in the self-renewal of spermatogonial stem cells (SSCs).
• To elucidate the signaling pathways involved in ROS-mediated SSC self-renewal.

Main Methods:

• Culture of SSCs with specific growth factors (GDNF, FGF2).
• Manipulation of ROS levels using hydrogen peroxide and ROS depletion.
• Analysis of signaling pathways including AKT, MEK, p38 MAPK, and JNK.
• In vivo studies involving ROS depletion and NADPH oxidase 1 (Nox1) deficiency.
• Serial transplantation assays to assess SSC self-renewal capacity.

Main Results:

• Physiological levels of ROS, generated via AKT and MEK pathways, stimulate SSC self-renewal.
• ROS depletion halts SSC proliferation, while increased ROS enhances self-renewal by activating p38 MAPK and JNK.
• In vivo ROS depletion reduces SSC numbers, and Nox1-deficient SSCs show impaired self-renewal.

Conclusions:

• ROS generated by Nox1 are critical for SSC self-renewal.
• ROS signaling via p38 MAPK and JNK pathways is essential for maintaining SSC proliferation and function.
• Contrary to previous assumptions, ROS play a vital role in supporting spermatogenesis by regulating SSC self-renewal.