Cloning of mouse BMAL2 and its daily expression profile in the suprachiasmatic nucleus: a remarkable acceleration of Bmal2 sequence divergence after Bmal gene duplication.
Brain-Muscle-Arnt-Like-protein 2 (BMAL2; Arnt4) (aryl hydrocarbon receptor nuclear translocator) is a recently identified basic Helix-Loop-Helix-Per-Arnt-Sim (bHLH-PAS) transcription factor, which contributes to a positive regulation of autoregulatory feedback loop in vertebrate circadian clock systems. In this study, we cloned cDNAs encoding mouse and rat BMAL2 (mBMAL2 and rBMAL2) from mouse midbrain and rat-1 fibroblast cells, respectively. A phylogenetic analysis strongly suggested that vertebrate Bmal1 and Bmal2 genes were generated by a single gene duplication of an ancestral Bmal gene, a vertebrate ortholog of dCyc gene, and that 'BMAL2's putatively termed so far are orthologous. Interestingly, BMAL2 proteins have diverged about 20-fold more rapidly than BMAL1 proteins after the duplication, suggesting an as-yet-unidentified function conserved in BMAL1 but not in BMAL2. mBmal2 mRNA was constitutively expressed throughout the day under light-dark cycle in the mouse hypothalamus containing suprachiasmatic nucleus, the site of the central circadian oscillator in mammals.
Okano
T
T
Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, Japan.
Sasaki
M
M
Fukada
Y
Y
D056930:ARNTL Transcription Factors; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins; D001683:Biological Clocks / Q000235:genetics*; D002940:Circadian Rhythm / Q000235:genetics*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics / Q000302:isolation & purification; D019143:Evolution, Molecular; D005347:Fibroblasts / Q000378:metabolism; D020440:Gene Duplication; D005786:Gene Expression Regulation / Q000502:physiology*; D008636:Mesencephalon / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009474:Neurons / Q000378:metabolism; D010802:Phylogeny; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D013493:Suprachiasmatic Nucleus / Q000166:cytology / Q000378:metabolism*; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism
D056930:ARNTL Transcription Factors; D051792:Basic Helix-Loop-Helix Proteins; D018076:DNA, Complementary; D012333:RNA, Messenger; D014157:Transcription Factors; C538961:Bmal1 protein, mouse; C431792:Arntl2 protein, mouse; C486616:Arntl2 protein, rat