Cell-type specific circadian bioluminescence rhythms inDbpreporter mice

Abstract

Circadian rhythms are endogenously generated physiological and molecular rhythms with a cycle length of about 24 h. Bioluminescent reporters have been exceptionally useful for studying circadian rhythms in numerous species. Here, we report development of a reporter mouse generated by modification of a widely expressed and highly rhythmic gene encoding D-site albumin promoter binding protein (Dbp). In this line of mice, firefly luciferase is expressed from the Dbp locus in a Cre-recombinase-dependent manner, allowing assessment of bioluminescence rhythms in specific cellular populations. A mouse line in which luciferase expression was Cre-independent was also generated. The Dbp reporter alleles do not alter Dbp gene expression rhythms in liver or circadian locomotor activity rhythms. In vitro and In vivo studies show the utility of the reporter alleles for monitoring rhythmicity. Our studies reveal cell-type specific characteristics of rhythms among neuronal populations within the suprachiasmatic nuclei in vitro. In vivo studies show stable Dbp-driven bioluminescence rhythms in the liver of Albumin-Cre;DbpKI/+ liver reporter mice. After a shift of the lighting schedule, locomotor activity achieved the proper phase relationship with the new lighting cycle more rapidly than hepatic bioluminescence did. As previously shown, restricting food access to the daytime altered the phase of hepatic rhythmicity. Our model allowed assessment of the rate of recovery from misalignment once animals were provided with food ad libitum. These studies provide clear evidence for circadian misalignment following environmental perturbations and reveal the utility of this model for minimally invasive, longitudinal monitoring of rhythmicity from specific mouse tissues.

Dim light in the evening causes coordinated realignment of circadian rhythms, sleep, and short-term memory

“…Detailed analyses of locomotor activity and immobility-defined sleep under normal and abnormal lighting conditions did not reveal any difference between sexes or genotypes; thus, male C57BL/6 WT mice (Envigo; RRID: IMSR_ JAX:000664) were used in subsequent experiments. In the DD experiment in which in vivo hepatic bioluminescence and locomotor activity were examined, 16 Albumin-Cre;Dbp KI/+ liver reporter mice (9\ and 7_) were used (57).…”

“…In Vivo Hepatic Dbp Bioluminescence. A total of 16 Albumin-Cre;Dbp KI/+ mice expressing firefly luciferase in hepatocytes under the control of Dbp were used to measure hepatic Dbp bioluminescence signals in vivo (57). They were first singly housed under LD for at least 8 wk.…”