ATF4 Is Dispensable for Spermatogenesis but Protective Against ER Stress Under Normal Conditions

Area of Science:

• Molecular Biology
• Reproductive Biology
• Cellular Stress Response

Background:

• Spermatogenesis is a complex, energy-demanding process sensitive to cellular stress.
• The integrated stress response (ISR) and its key mediator, ATF4, are crucial for cellular adaptation.
• The specific role of ATF4 in mammalian spermatogenesis remained unclear.

Purpose of the Study:

• To investigate the functional significance of ATF4 in mammalian spermatogenesis.
• To determine if ATF4 is essential for male fertility and testicular function.

Main Methods:

• Generation of a germ cell-specific Atf4 conditional knockout mouse model.
• Assessment of testicular histology and sperm parameters in knockout mice.
• Proteomic analysis to evaluate proteome-wide changes in Atf4-deficient testes.

Main Results:

• Atf4 deletion did not affect spermatogenesis, male fertility, testicular histology, or sperm parameters.
• Proteomic analysis revealed significant dysregulation of the testicular proteome in Atf4 knockout mice.
• Deficiency in ATF4 impacted the downregulation of SQSTM1/p62 via the endoplasmic reticulum stress pathway.

Conclusions:

• ATF4's role in regulating proteostasis is separable from its necessity for spermatogenesis progression.
• ATF4 acts as a resilience factor protecting testicular function during endoplasmic reticulum stress.
• ATF4 is not a direct regulator of male germ cell development but safeguards testicular homeostasis.