The molecular clock protein Bmal1 regulates cell differentiation in mouse embryonic stem cells

Area of Science:

• Developmental Biology
• Chronobiology
• Stem Cell Biology

Background:

• Mammalian physiology synchronizes to the light-dark cycle via master and peripheral circadian clocks.
• Circadian rhythms depend on the molecular clock's negative feedback loop involving BMAL1, CLOCK, PER, and CRY proteins.
• Molecular clock components are expressed early, but robust oscillations emerge later in embryogenesis.

Purpose of the Study:

• To investigate the role of Bmal1 in early mammalian development using pluripotent mouse embryonic stem cells (mESCs).

Main Methods:

• Utilized naïve pluripotent mouse embryonic stem cells (mESCs) to study Bmal1 function.
• Compared gene and protein expression in wild-type and Bmal1 knockout (Bmal1-/-) mESCs.
• Assessed multi-lineage differentiation capacity using teratoma formation and gastrula-like organoid models.

Main Results:

• Bmal1-/- mESCs exhibited elevated Nanog protein levels and altered expression of pluripotency signaling pathways compared to wild-type cells.
• Bmal1 deficiency led to impaired multi-lineage cell differentiation capacity in both teratomas and gastruloids.
• These findings indicate Bmal1 is essential for proper differentiation of pluripotent stem cells.

Conclusions:

• Bmal1 plays a significant role in regulating pluripotent cell differentiation during early mammalian development.
• The molecular clock, previously unappreciated, is identified as a key regulator of mammalian development.
• This study reveals a novel function for the circadian clock machinery in stem cell biology and embryogenesis.