Nocturnin (Noct), also known as Ccrn4l, is a protein encoded by the Noct gene. It belongs to the EEP family of proteins, with close similarity to the CCR4 family of deadenylases. Noct is an output of the circadian clock, and its mRNA is broadly expressed in cells throughout the body, with a particularly high-amplitude rhythm in the liver. It is involved in multiple biological processes such as development, adipogenesis, lipid metabolism, inflammation, osteogenesis, and obesity, and is also associated with the regulation of NAD(H) and NADP(H) homeostasis [1,2].

Mice lacking Noct (Noct KO or Noct-/-) are protected from high-fat diet-induced obesity and hepatic steatosis, indicating that Noct plays a role in lipid metabolism and obesity-related processes [1]. A mouse model overexpressing Noct showed decreased fat mass in male mice, likely through its role as a mediator of mitochondrial function [3].

In conclusion, Noct is a key gene regulated by the circadian clock. Model-based research, especially the use of Noct KO mouse models, has revealed its important functions in lipid metabolism, adipogenesis, and obesity-related diseases. Understanding Noct's functions provides insights into the molecular mechanisms underlying these biological processes and diseases.