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Rhythmic expression of Nocturnin mRNA in multiple tissues of the mouse.

Wang Y, Osterbur DL, Megaw PL, Tosini G, Fukuhara C, Green CB, Besharse JC - BMC Dev. Biol. (2001)

Bottom Line: Nocturnin was originally identified by differential display as a circadian clock regulated gene with high expression at night in photoreceptors of the African clawed frog, Xenopus laevis.Furthermore, mNoc exhibits circadian rhythmicity of mRNA abundance with peak levels at the time of light offset in the retina, spleen, heart, kidney and liver.The widespread expression and rhythmicity of mNoc mRNA parallels the widespread expression of other circadian clock genes in mammalian tissues, and suggests that nocturnin plays an important role in clock function or as a circadian clock effector.

View Article: PubMed Central - HTML - PubMed

Affiliation: PEL-FREEZ Clinical Systems, LLC, 9099 North Deerbrook Trail, Brown Deer, WI 53223, USA. ywang@pel-freez.com

ABSTRACT

Background: Nocturnin was originally identified by differential display as a circadian clock regulated gene with high expression at night in photoreceptors of the African clawed frog, Xenopus laevis. Although encoding a novel protein, the nocturnin cDNA had strong sequence similarity with a C-terminal domain of the yeast transcription factor CCR4, and with mouse and human ESTs. Since its original identification others have cloned mouse and human homologues of nocturnin/CCR4, and we have cloned a full-length cDNA from mouse retina, along with partial cDNAs from human, cow and chicken. The goal of this study was to determine the temporal pattern of nocturnin mRNA expression in multiple tissues of the mouse.

Results: cDNA sequence analysis revealed a high degree of conservation among vertebrate nocturnin/CCR4 homologues along with a possible homologue in Drosophila. Northern analysis of mRNA in C3H/He and C57/Bl6 mice revealed that the mNoc gene is expressed in a broad range of tissues, with greatest abundance in liver, kidney and testis. mNoc is also expressed in multiple brain regions including suprachiasmatic nucleus and pineal gland. Furthermore, mNoc exhibits circadian rhythmicity of mRNA abundance with peak levels at the time of light offset in the retina, spleen, heart, kidney and liver.

Conclusion: The widespread expression and rhythmicity of mNoc mRNA parallels the widespread expression of other circadian clock genes in mammalian tissues, and suggests that nocturnin plays an important role in clock function or as a circadian clock effector.

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mNoc mRNA is expressed rhythmically in 8 week old BALB/c mouse liver (A) and kidney (B) in a light dark cycle (LD). Tissues for RNA extraction were collected at Zeitgeber Times (ZT) 0 (24), 6, 12 and 18 with lights on at ZT 0 and off at ZT12. Images of the methylene blue stained 28S and 18S rRNA bands on the same blot are shown below as loading controls.
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Figure 7: mNoc mRNA is expressed rhythmically in 8 week old BALB/c mouse liver (A) and kidney (B) in a light dark cycle (LD). Tissues for RNA extraction were collected at Zeitgeber Times (ZT) 0 (24), 6, 12 and 18 with lights on at ZT 0 and off at ZT12. Images of the methylene blue stained 28S and 18S rRNA bands on the same blot are shown below as loading controls.

Mentions: We tested the hypothesis that the IAP element in Intron I of BALB/c mice ([14,36] see Fig. 6) would disrupt rhythmic expression of mNoc. Six week old BALB/c mice were kept in our animal facilities for two weeks and liver and kidney tissues were obtained for Northern analysis at 6 hour intervals through a light-dark cycle. As shown in Figure 7, mNoc in BALB/c mouse liver and kidney clearly exhibits rhythmicity similar to that seen in C3H/He mice with a prominent mRNA band at approximately 3 kb. Less abundant larger bands are also seen above 4 kb (liver and kidney) and 8 kb (liver only). Although larger mRNA bands have been reported to reflect hybrid transcripts including components of the IAP element in aging BALB/c mice, it is unclear whether this would explain the larger bands in Figure 7. The bands in Figure 7 are smaller than the 6 and 10 kb bands reported in old mice [38,39] and follow a rhythmic pattern similar to that of the 3 kb band. The larger bands could reflect splicing intermediates that are seen only during the period of maximal transcription of mNoc. Although it is possible that altered transcription of mNoc as a consequence of an interaction between aging and the IAP insert may alter the rhythmic pattern of expression [39], our data clearly indicate that the mere presence of the IAP element in mice 8 weeks of age has little or no impact on rhythmic expression. Comparable results have been obtained using C57/Bl6 and CBA/J mice (data not shown).


Rhythmic expression of Nocturnin mRNA in multiple tissues of the mouse.

Wang Y, Osterbur DL, Megaw PL, Tosini G, Fukuhara C, Green CB, Besharse JC - BMC Dev. Biol. (2001)

mNoc mRNA is expressed rhythmically in 8 week old BALB/c mouse liver (A) and kidney (B) in a light dark cycle (LD). Tissues for RNA extraction were collected at Zeitgeber Times (ZT) 0 (24), 6, 12 and 18 with lights on at ZT 0 and off at ZT12. Images of the methylene blue stained 28S and 18S rRNA bands on the same blot are shown below as loading controls.
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Related In: Results  -  Collection

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Figure 7: mNoc mRNA is expressed rhythmically in 8 week old BALB/c mouse liver (A) and kidney (B) in a light dark cycle (LD). Tissues for RNA extraction were collected at Zeitgeber Times (ZT) 0 (24), 6, 12 and 18 with lights on at ZT 0 and off at ZT12. Images of the methylene blue stained 28S and 18S rRNA bands on the same blot are shown below as loading controls.
Mentions: We tested the hypothesis that the IAP element in Intron I of BALB/c mice ([14,36] see Fig. 6) would disrupt rhythmic expression of mNoc. Six week old BALB/c mice were kept in our animal facilities for two weeks and liver and kidney tissues were obtained for Northern analysis at 6 hour intervals through a light-dark cycle. As shown in Figure 7, mNoc in BALB/c mouse liver and kidney clearly exhibits rhythmicity similar to that seen in C3H/He mice with a prominent mRNA band at approximately 3 kb. Less abundant larger bands are also seen above 4 kb (liver and kidney) and 8 kb (liver only). Although larger mRNA bands have been reported to reflect hybrid transcripts including components of the IAP element in aging BALB/c mice, it is unclear whether this would explain the larger bands in Figure 7. The bands in Figure 7 are smaller than the 6 and 10 kb bands reported in old mice [38,39] and follow a rhythmic pattern similar to that of the 3 kb band. The larger bands could reflect splicing intermediates that are seen only during the period of maximal transcription of mNoc. Although it is possible that altered transcription of mNoc as a consequence of an interaction between aging and the IAP insert may alter the rhythmic pattern of expression [39], our data clearly indicate that the mere presence of the IAP element in mice 8 weeks of age has little or no impact on rhythmic expression. Comparable results have been obtained using C57/Bl6 and CBA/J mice (data not shown).

Bottom Line: Nocturnin was originally identified by differential display as a circadian clock regulated gene with high expression at night in photoreceptors of the African clawed frog, Xenopus laevis.Furthermore, mNoc exhibits circadian rhythmicity of mRNA abundance with peak levels at the time of light offset in the retina, spleen, heart, kidney and liver.The widespread expression and rhythmicity of mNoc mRNA parallels the widespread expression of other circadian clock genes in mammalian tissues, and suggests that nocturnin plays an important role in clock function or as a circadian clock effector.

View Article: PubMed Central - HTML - PubMed

Affiliation: PEL-FREEZ Clinical Systems, LLC, 9099 North Deerbrook Trail, Brown Deer, WI 53223, USA. ywang@pel-freez.com

ABSTRACT

Background: Nocturnin was originally identified by differential display as a circadian clock regulated gene with high expression at night in photoreceptors of the African clawed frog, Xenopus laevis. Although encoding a novel protein, the nocturnin cDNA had strong sequence similarity with a C-terminal domain of the yeast transcription factor CCR4, and with mouse and human ESTs. Since its original identification others have cloned mouse and human homologues of nocturnin/CCR4, and we have cloned a full-length cDNA from mouse retina, along with partial cDNAs from human, cow and chicken. The goal of this study was to determine the temporal pattern of nocturnin mRNA expression in multiple tissues of the mouse.

Results: cDNA sequence analysis revealed a high degree of conservation among vertebrate nocturnin/CCR4 homologues along with a possible homologue in Drosophila. Northern analysis of mRNA in C3H/He and C57/Bl6 mice revealed that the mNoc gene is expressed in a broad range of tissues, with greatest abundance in liver, kidney and testis. mNoc is also expressed in multiple brain regions including suprachiasmatic nucleus and pineal gland. Furthermore, mNoc exhibits circadian rhythmicity of mRNA abundance with peak levels at the time of light offset in the retina, spleen, heart, kidney and liver.

Conclusion: The widespread expression and rhythmicity of mNoc mRNA parallels the widespread expression of other circadian clock genes in mammalian tissues, and suggests that nocturnin plays an important role in clock function or as a circadian clock effector.

Show MeSH
Related in: MedlinePlus