Circadian clock core component Bmal1 dictates cell cycle rhythm of proliferating hepatocytes during liver regeneration.
Level 5 - mechanism / opinion, no new human data
Animal research without human clinical data
PubMed 34431407 · doi:10.1152/ajpgi.00204.2021
What was done
Researchers investigated the role of the circadian clock component Bmal1 in liver regeneration by performing partial hepatectomy on wild-type (Bmal1 +/+) and hepatocyte-specific knockout (Bmal1 hep-/-) mice. They tracked hepatocyte cell cycle entry and progression, waves of nuclear DNA synthesis, mitotic oscillations, expression of cell cycle regulators, activation of c-Met and EGFR mitogenic signaling, rhythmic lipid accumulation, and late-stage activation of the redox sensor Nrf2 from the abstract.
What was found
Following partial hepatectomy, wild-type hepatocytes underwent three waves of nuclear DNA synthesis and three waves of mitosis, accompanied by rhythmic fat accumulation. In Bmal1 hep-/- hepatocytes, the first wave of nuclear DNA synthesis was delayed by 12 h, the third wave was lost, and mitotic oscillations were completely abolished. Knockout mice also showed suppressed expression peaks of cell cycle components, altered c-Met and EGFR activation patterns, inhibited fat accumulation, and activation of Nrf2. Beyond the 12 h delay, no numerical data or sample sizes were reported in the abstract.
Why it matters
This work identifies Bmal1 as a central regulator of the timing of DNA replication, cell division, and lipid metabolism during post-injury liver regeneration in mice. It connects molecular circadian clock function to the coordination of hepatic tissue repair.
Limits
The study is restricted to an animal model with no human validation. The abstract omits sample sizes (n), quantitative statistical metrics, and evaluations of overall functional liver recovery or survival.
Cited by
- context In mouse partial hepatectomy models, mice operated on in the evening recover significantly faster than mice operated on in the daytime.