Circadian regulation of islet genes involved in insulin production and secretion.
Both transcription factors albumin site d-binding protein (DBP) and thyrotroph embryonic factor (TEF) are elements of the "cell-clock". Their circadian accumulation in suprachiasmatic nucleus (SCN) and peripheral tissues such as liver, kidney and lung is thought to participate in controlling circadian regulation of downstream genes. TEF and DBP control elements have never been investigated in the insulin-secreting cells, but impairment of the circadian rhythm of the beta-cells might be involved in the development of diabetic state as type 2 diabetics have lost daily temporal variations of insulin secretion. We investigated the expression pattern of TEF and DBP in insulin-secreting cells. TEF and DBP transcripts are expressed at extremely high levels in human pancreatic islets compared to other tissues, suggesting a potentially important circadian regulation of these cells. Both TEF and DPB accumulate in a circadian way in insulin-secreting cells after a serum shock known to restore circadian rhythms in cultured cells. In addition, the expression of islet-specific genes involved in glucose sensing (glucose transporter 2 (Glut2), glucokinase), insulin production (insulin) and secretion (migration inhibitory factor (MIF), somatostatin and syntaxin 1A) were modulated in the same daily rhythm as well. The circadian deregulation of these genes could therefore participate in the diabetic state development.
Service of Medical Genetics and Unit of Molecular Genetics, Centre Hospitalier Universitaire Vaudois (CHUV), CH-1011 Lausanne, Switzerland. Nathalie.Pillet@chuv.hospvd.ch
N
N
Allaman-Pillet
R
R
Roduit
A
A
Oberson
S
S
Abdelli
J
J
Ruiz
J S
JS
Beckmann
D F
DF
Schorderet
C
C
Bonny
D000954:Antigens, Surface / Q000378:metabolism; D050976:Basic-Leucine Zipper Transcription Factors; D002940:Circadian Rhythm; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005786:Gene Expression Regulation; D005941:Glucokinase / Q000378:metabolism; D051273:Glucose Transporter Type 2; D006801:Humans; D007328:Insulin / Q000096:biosynthesis* / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000378:metabolism*; D008263:Macrophage Migration-Inhibitory Factors / Q000378:metabolism; D009004:Monosaccharide Transport Proteins / Q000235:genetics / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D011401:Promoter Regions, Genetic; D013004:Somatostatin / Q000378:metabolism; D013493:Suprachiasmatic Nucleus / Q000378:metabolism; D050827:Syntaxin 1; D014157:Transcription Factors / Q000378:metabolism*
D000954:Antigens, Surface; D050976:Basic-Leucine Zipper Transcription Factors; C063898:DBP protein, human; D004268:DNA-Binding Proteins; D051273:Glucose Transporter Type 2; D007328:Insulin; D008263:Macrophage Migration-Inhibitory Factors; D009004:Monosaccharide Transport Proteins; D009419:Nerve Tissue Proteins; C494212:STX1A protein, human; D050827:Syntaxin 1; C489490:TEF protein, human; D014157:Transcription Factors; D013004:Somatostatin; D005941:Glucokinase