Bmal2, also known as ARNTL2, is a member of the basic helix-loop-helix PER-ARNT-SIM family of transcription factors. It forms heterodimers with CLOCK and NPAS2 to activate the transcription of clock and clock-controlled genes, playing a crucial role in regulating circadian rhythms. It is also involved in various biological processes such as metabolism, immune response, and cell proliferation, making it an important gene for understanding physiological and pathological conditions. Gene knockout models, like the Bmal2 knockout (B2KO) mouse model, are valuable tools for studying its functions [2,3].

In B2KO male mice, there are significant alterations. They show increased adiposity and fasted hyperinsulinemia, with lower energy expenditure at night. The master clock in the suprachiasmatic nuclei is impaired, as indicated by a shorter free-running period and loss of daily rhythmicity in the expression of intracellular metabolic regulators. The circadian window of eating is longer, and the circadian patterns of food intake and meal numbers change. Also, food-anticipatory activity is almost prevented, suggesting an altered food clock. In the mediobasal hypothalamus of B2KO mice, the expression of orexigenic neuropeptide-coding genes is downregulated, and Lipoprotein lipase expression loses its rhythmicity [2]. In pancreatic cancer cell lines, knockout of Bmal2 affects cell viability, invasion, glycolysis, and other metabolic processes under hypoxic conditions. Bmal2 directly regulates hypoxia-responsive target genes and is necessary for the stabilization of HIF1A and destabilization of HIF2A upon exposure to hypoxia [1].

In conclusion, Bmal2 is essential for maintaining normal circadian regulation of metabolism, feeding behavior, and energy balance as revealed by the B2KO mouse model. It also plays a significant role in hypoxic metabolism in pancreatic cancer. Understanding Bmal2 through such model-based research provides insights into the mechanisms of metabolic disorders and cancer, potentially guiding the development of new therapeutic strategies.