Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

Bmal1 controls circadian cell proliferation and susceptibility to UVB-induced DNA damage in the epidermis [Anagen]

ABSTRACT: While several physiological skin parameters vary in a circadian manner, the identity of genes participating in chronobiology of skin remains unknown, leading us to define the circadian transcriptome of mouse skin at two different stages of the hair cycle, telogen and anagen. The circadian transcriptomes of telogen and anagen skin are largely distinct, with the former dominated by genes involved in cell proliferation and metabolism. The expression of many metabolic genes is antiphasic to cell cycle related genes, the former peaking during the day and the latter peaking at the night. Consistently, accumulation of reactive oxygen species, a byproduct of oxidative phosphorylation, and S-phase are antiphasic to each other in telogen skin. Furthermore, the circadian variation in S-phase is controlled by BMAL1 intrinsic to keratinocytes as keratinocyte-specific deletion of Bmal1 obliterates time of day dependent synchronicity of cell division in the epidermis leading to a constitutively elevated cell proliferation. Consistent with higher cellular susceptibility to UV-induced DNA damage during S phase, we found that mice are most sensitive to UVB-induced DNA damage in the epidermis at night. As maximum numbers of keratinocytes go through S phase in the late afternoon in the human epidermis, we speculate that in humans the circadian clock imposes regulation of epidermal cell proliferation such that skin is at a particularly vulnerable stage during times of maximum UV exposure, thus contributing to the high incidence of human skin cancers. Whole skin was collected at 4 hour intervals for 48 hours. ZT number indicates the number of hours elapsed from when lights are switched on. ZT0 = lights on (6am). ZT12=lights off (6pm). Total RNA was purified from the skin of each mouse and equal amount of RNA from the 3 replicates for each time point were pooled. Anagen samples were collected from skin of P30 male mice.

ORGANISM(S): Mus musculus

SUBMITTER: mikhail geyfman

PROVIDER: E-GEOD-38623 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Publications

Brain and muscle Arnt-like protein-1 (BMAL1) controls circadian cell proliferation and susceptibility to UVB-induced DNA damage in the epidermis.

Geyfman Mikhail M Kumar Vivek V Liu Qiang Q Ruiz Rolando R Gordon William W Espitia Francisco F Cam Eric E Millar Sarah E SE Smyth Padhraic P Ihler Alexander A Takahashi Joseph S JS Andersen Bogi B

Proceedings of the National Academy of Sciences of the United States of America 20120702 29

The role of the circadian clock in skin and the identity of genes participating in its chronobiology remain largely unknown, leading us to define the circadian transcriptome of mouse skin at two different stages of the hair cycle, telogen and anagen. The circadian transcriptomes of telogen and anagen skin are largely distinct, with the former dominated by genes involved in cell proliferation and metabolism. The expression of many metabolic genes is antiphasic to cell cycle-related genes, the for ...[more]

PMID: 22753467

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Project description:Hair follicles undergo recurrent cycling of controlled growth (anagen), regression (catagen), and relative quiescence (telogen) with a defined periodicity. Taking a genomics approach to study gene expression during synchronized mouse hair follicle cycling, we discovered that, in addition to circadian fluctuation, CLOCK-regulated genes are also modulated in phase with the hair growth cycle. During telogen and early anagen, circadian clock genes are prominently expressed in the secondary hair germ, which contains precursor cells for the growing follicle. Analysis of Clock and Bmal1 mutant mice reveals a delay in anagen progression, and the secondary hair germ cells show decreased levels of phosphorylated Rb and lack mitotic cells, suggesting that circadian clock genes regulate anagen progression via their effect on the cell cycle. Consistent with a block at the G1 phase of the cell cycle, we show a significant upregulation of p21 in Bmal1 mutant skin. While circadian clock mechanisms have been implicated in a variety of diurnal biological processes, our findings indicate that circadian clock genes may be utilized to modulate the progression of non-diurnal cyclic processes. To investigate the molecular control of hair follicle cycling, we profiled mRNA expression in mouse dorsal skin at multiple representative time points in the synchronized second postnatal hair growth cycle and in a depilation-induced hair growth cycle. For profiling of second synchronized and depilation-induced hair growth cycle, the same upper-mid region of dorsal skin was excised from C57BL/6 mice at representative postnatal days (P). The time points for second hair growth cycle are classified into different phases of the hair growth cycle based on established morphological guidelines as follow: early anagen (P23, P25), mid anagen (P27), late anagen (P29, P34), early catagen (P37, P39), mid catagen (P41), and telogen (P44). Depilation-induced hair growth cycle by applying wax/rosin mixture on the dorsal skin of seven-week old mice (all follicles in telogen) was performed on mice. The corresponding phases of the hair growth cycle at number of days following depilation (D) is as follow: early anagen (D3), mid anagen (D5), late anagen (D8, D12), and early catagen (D17). For each time point, multiple biological replicates were profiled, with each mouse dorsal skin separately hybridized to an Affymetrix array.

Dataset Information

Bmal1 controls circadian cell proliferation and susceptibility to UVB-induced DNA damage in the epidermis [Anagen]

Publications

Brain and muscle Arnt-like protein-1 (BMAL1) controls circadian cell proliferation and susceptibility to UVB-induced DNA damage in the epidermis.

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