Phenotype matters: identification of light-responsive cells in the mouse suprachiasmatic nucleus.
The suprachiasmatic nucleus (SCN) of the hypothalamus is the neural locus of the circadian clock. To explore the organization of the SCN, two strains of transgenic mice, each bearing a jellyfish green fluorescent protein (GFP) reporter, were used. In one, GFP was driven by the promoter region of the mouse Period1 gene (mPer1) (Per1::GFP mouse), whereas in the other, GFP was inserted in the promoter region of calbindin-D(28K)-bacterial artificial chromosome (CalB::GFP mouse). In the latter mouse, GFP-containing SCN cells are immunopositive for gastrin-releasing peptide. In both mouse lines, light-induced Per1 mRNA and Fos are localized to the SCN subregion containing gastrin-releasing peptide. Double-label immunohistochemistry reveals that most gastrin-releasing peptide cells (approximately 70%) contain Fos after a brief light pulse. To determine the properties of SCN cells in this light-responsive region, we examined the expression of rhythmic Period genes and proteins. Gastrin-releasing peptide-containing cells do not express detectable rhythms in these key components of the molecular circadian clock. The results support the view that the mammalian SCN is composed of functionally distinct cell groups, of which some are light induced and others are rhythmic with respect to clock gene expression. Furthermore, the findings suggest that gastrin-releasing peptide is a potential mediator of intercellular communication between light-induced and oscillator cells within the SCN.
Karatsoreos
Ilia N
IN
Department of Psychology, Columbia University, New York, New York 10027, USA.
Yan
Lily
L
LeSauter
Joseph
J
Silver
Rae
R
D000818:Animals; D064026:Calbindins; D018797:Cell Cycle Proteins; D002940:Circadian Rhythm; D019886:Gastrin-Releasing Peptide / Q000032:analysis; D005786:Gene Expression Regulation; D049452:Green Fluorescent Proteins; D008027:Light; D008164:Luminescent Proteins / Q000032:analysis / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D009687:Nuclear Proteins / Q000096:biosynthesis / Q000235:genetics; D056950:Period Circadian Proteins; D010641:Phenotype; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D064030:S100 Calcium Binding Protein G / Q000235:genetics; D013493:Suprachiasmatic Nucleus / Q000166:cytology* / Q000378:metabolism / Q000528:radiation effects*
D064026:Calbindins; D018797:Cell Cycle Proteins; D008164:Luminescent Proteins; D009687:Nuclear Proteins; C539023:Per1 protein, mouse; D056950:Period Circadian Proteins; D012333:RNA, Messenger; D064030:S100 Calcium Binding Protein G; D049452:Green Fluorescent Proteins; D019886:Gastrin-Releasing Peptide