Human intestinal circadian clock: expression of clock genes in colonocytes lining the crypt.
Biological clock components have been detected in many epithelial tissues of the digestive tract of mammals (oral mucosa, pancreas, and liver), suggesting the existence of peripheral circadian clocks that may be entrainable by food. Our aim was to investigate the expression of main peripheral clock genes in colonocytes of healthy humans and in human colon carcinoma cell lines. The presence of clock components was investigated in single intact colonic crypts isolated by chelation from the biopsies of 25 patients (free of any sign of colonic lesions) undergoing routine colonoscopy and in cell lines of human colon carcinoma (Caco2 and HT29 clone 19A). Per-1, per-2, and clock mRNA were detected by real-time RT-PCR. The three-dimensional distributions of PER-1, PER-2, CLOCK, and BMAL1 proteins were recorded along colonic crypts by immunofluorescent confocal imaging. We demonstrate the presence of per-1, per-2, and clock mRNA in samples prepared from colonic crypts of 5 patients and in all cell lines. We also demonstrate the presence of two circadian clock proteins, PER-1 and CLOCK, in human colonocytes on crypts isolated from 20 patients (15 patients for PER-1 and 6 for CLOCK) and in colon carcinoma cells. Establishing the presence of clock proteins in human colonic crypts is the first step toward the study of the regulation of the intestinal circadian clock by nutrients and feeding rhythms.
Pardini
L
L
CRNH de Nantes, INRA, Unité Fonctions Digestives et Nutrition Humaine, Nantes, France.
Kaeffer
B
B
Trubuil
A
A
Bourreille
A
A
Galmiche
J-P
JP
D056930:ARNTL Transcription Factors; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics; D001683:Biological Clocks / Q000502:physiology*; D056926:CLOCK Proteins; D018797:Cell Cycle Proteins; D045744:Cell Line, Tumor; D002940:Circadian Rhythm / Q000502:physiology*; D003106:Colon / Q000502:physiology*; D003110:Colonic Neoplasms; D066246:ErbB Receptors / Q000235:genetics; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D007413:Intestinal Mucosa / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009687:Nuclear Proteins / Q000235:genetics; D056950:Period Circadian Proteins; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015534:Trans-Activators / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics
D056930:ARNTL Transcription Factors; D051792:Basic Helix-Loop-Helix Proteins; D056926:CLOCK Proteins; D018797:Cell Cycle Proteins; D066246:ErbB Receptors; D009687:Nuclear Proteins; D056950:Period Circadian Proteins; D012333:RNA, Messenger; D015534:Trans-Activators; D014157:Transcription Factors; C538960:BMAL1 protein, human; C539022:PER1 protein, human; C421902:PER2 protein, human; C538943:CLOCK protein, human