Distinct germline progenitor subsets defined through Tsc2-mTORC1 signaling.

Area of Science:

• Stem cell biology
• Reproductive biology
• Molecular signaling

Background:

• Adult tissue maintenance depends on resident stem cells.
• Phenotypic and functional heterogeneity within stem cell populations is poorly understood.
• Spermatogonial progenitor cells (SPCs) are crucial for male fertility.

Purpose of the Study:

• To define distinct SPC subsets based on their response to mTORC1 pathway activation.
• To investigate the role of mTORC1 signaling in regulating SPC self-renewal and differentiation.
• To understand the impact of Tsc2 deletion on SPC function and germline integrity.

Main Methods:

• Conditional deletion of Tsc2 in SPCs using Vasa-Cre and Stra8-Cre.
• Analysis of SPC function and germline integrity following genetic manipulation.
• Comparison of mTORC1 activity in differentiation-prone versus self-renewing SPCs.

Main Results:

• Conditional deletion of Tsc2 in the entire SPC pool led to differentiation and germline degeneration.
• Tsc2 ablation in a subset of SPCs or in niche somatic cells did not impair SPC function.
• Differentiation-prone SPCs exhibited higher mTORC1 activity compared to self-renewing SPCs.
• SPCs insensitive to Tsc2 deletion were linked to mTORC1-active committed progenitor fractions.

Conclusions:

• mTORC1 activity levels delineate distinct SPC subpopulations with varying self-renewal and differentiation potentials.
• mTORC1 acts as a key regulator of SPC fate, influencing their response to genetic perturbations.
• Understanding SPC heterogeneity is critical for comprehending germline maintenance and potential therapeutic interventions.