Human Circadian Molecular Oscillation Development Using Induced Pluripotent Stem Cells

Area of Science:

• Developmental Biology
• Chronobiology
• Stem Cell Biology

Background:

• Mammalian circadian clocks orchestrate physiological functions and mature gradually during development.
• Previous research identified posttranscriptional suppression of CLOCK protein as crucial for mouse circadian clock emergence.
• The conserved mechanisms regulating human circadian clock development remain largely unexplored.

Purpose of the Study:

• To investigate the developmental emergence of circadian molecular oscillations in human induced pluripotent stem cells (iPSCs).
• To determine if posttranscriptional suppression of CLOCK protein is also a key mechanism in human circadian clock development.

Main Methods:

• Culturing human induced pluripotent stem cells (iPSCs) in vitro.
• Monitoring circadian molecular oscillations during differentiation.
• Analyzing CLOCK protein and mRNA expression levels in undifferentiated and differentiating iPSCs.

Main Results:

• Undifferentiated human iPSCs exhibited no discernible circadian molecular oscillations.
• The emergence of circadian oscillations in differentiating human iPSCs required a prolonged culture duration compared to mice.
• CLOCK protein expression was posttranscriptionally suppressed in undifferentiated human iPSCs, despite detectable CLOCK mRNA levels.

Conclusions:

• Circadian molecular oscillations do not manifest in early human development, as shown by iPSCs.
• Posttranscriptional suppression of CLOCK protein is a conserved mechanism regulating the emergence of the circadian clock in both humans and mice.
• This finding provides critical insights into the developmental regulation of the human circadian system.