The body’s daily clock protein BMAL1 is needed for fertility and normal testosterone levels in mice

Both male and female mice lacking the Bmal1 gene are infertile.

• Bmal1 knockout mice exhibit deficiencies in steroid hormone production.
• Male Bmal1 KO mice show low testosterone levels and high luteinizing hormone concentrations.
• BMAL1 protein is rhythmically expressed in Leydig cells, indicating its role in testosterone regulation.
• Expression of the steroidogenic acute regulatory protein (StAR), crucial for steroid hormone production, is decreased in the testes of Bmal1 KO mice.
• In vitro experiments suggest that BMAL1 enhances StAR transcription in Leydig cells.
• Other hormonal abnormalities in male Bmal1 KO mice point to additional roles of BMAL1 in reproductive physiology beyond the testis.

Simplified