TY - JOUR
T1 - Hexose transporter expression and function in mouse small intestine
T2 - Role of diurnal rhythm
AU - Fatima, Javairiah
AU - Iqbal, Corey W.
AU - Houghton, Scott G.
AU - Kasparek, Michael S.
AU - Duenes, Judith A.
AU - Zheng, Ye
AU - Sarr, Michael G.
N1 - Funding Information:
Presented in part at Academic Surgical Congress in Phoenix, Arizona (Feb 7, 2007) and published in abstract form in Journal of Surgical Research (2007;137:255–256). This work was supported in part by the National Institutes of Health (Grant DK 39337-MGS). J.Fatima.C.W.Iqbal.S.G.Houghton.M.S.Kasparek. J. A. Duenes.Y. Zheng.M. G. Sarr (*) Gastroenterology Research Unit (GU 1001), Department of Surgery, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA e-mail: Sarr.Michael@mayo.edu
Funding Information:
the duodenum and jejunum peaked in an anticipatory fashion during the late hours of the light cycle and just before the onset of the dark cycle when feedings occurred; this increased transcription appeared to occur in preparation for translation into the transport proteins to coincide with maximal feeding during the dark cycle. Indeed, the protein levels for SGLT1, GLUT2, and GLUT5 displayed a diurnally varying pattern of expression in the jejunum with greatest expression at 3 AM. This finding was supported by the demonstration of maximal transporter-mediated uptake by the small intestine during the dark cycle when food intake was greatest. Also, associated with this increased uptake was a 1.6-fold increase in Vmax (a function of the number of transporters) from 9 AM to 9 PM, while Km, a function of the receptor’s transporter affinity for its
PY - 2009/4
Y1 - 2009/4
N2 - Background: Expression and function of hexose transporters vary diurnally in rat small intestine; however, this subject remains unexplored in mice. Aim: The aim of the study was to investigate the diurnal expression and function of hexose transporters SGLT1, GLUT2, and GLUT5 in mouse small bowel. Methods: Twenty-four c57bl6 mice maintained in a 12-h light/dark room (6 am-6 pm) were sacrificed at 9 am, 3 pm, 9 pm, and 3 am (n∈=∈6 each). In duodenal, jejunal, and ileal mucosa, total cellular mRNA and protein levels were quantitated by real-time PCR and semiquantitative Western blotting, respectively. The everted sleeve technique measured transporter-mediated glucose uptake at 9 am and 9 pm. Results: mRNA expression of SGLT1, GLUT2, and GLUT5 varied diurnally in all three intestinal segments (p∈ ∈0.03). SGLT1, GLUT2, and GLUT5 protein levels varied diurnally in duodenum and jejunum (p∈<∈0.05) but not in ileum. Transporter-mediated glucose uptake was greater at 9 pm than 9 am (p∈ ∈0.04) in all three segments. V max was greater in duodenum (10 vs 6 nmol/cm/s) and jejunum (8 vs 5 nmol/cm/s) at 9 pm compared to 9 am (p∈=∈0.01); K m remained unchanged. Summary: mRNA levels of intestinal hexose transporters varied diurnally. Protein levels peaked 6-12 h later during dark cycle when >70% of food intake occurred; glucose transport followed a similar pattern with increased uptake at 9 pm. Conclusion: Hexose transporter expression and function vary diurnally with nocturnal feeding patterns of mice.
AB - Background: Expression and function of hexose transporters vary diurnally in rat small intestine; however, this subject remains unexplored in mice. Aim: The aim of the study was to investigate the diurnal expression and function of hexose transporters SGLT1, GLUT2, and GLUT5 in mouse small bowel. Methods: Twenty-four c57bl6 mice maintained in a 12-h light/dark room (6 am-6 pm) were sacrificed at 9 am, 3 pm, 9 pm, and 3 am (n∈=∈6 each). In duodenal, jejunal, and ileal mucosa, total cellular mRNA and protein levels were quantitated by real-time PCR and semiquantitative Western blotting, respectively. The everted sleeve technique measured transporter-mediated glucose uptake at 9 am and 9 pm. Results: mRNA expression of SGLT1, GLUT2, and GLUT5 varied diurnally in all three intestinal segments (p∈ ∈0.03). SGLT1, GLUT2, and GLUT5 protein levels varied diurnally in duodenum and jejunum (p∈<∈0.05) but not in ileum. Transporter-mediated glucose uptake was greater at 9 pm than 9 am (p∈ ∈0.04) in all three segments. V max was greater in duodenum (10 vs 6 nmol/cm/s) and jejunum (8 vs 5 nmol/cm/s) at 9 pm compared to 9 am (p∈=∈0.01); K m remained unchanged. Summary: mRNA levels of intestinal hexose transporters varied diurnally. Protein levels peaked 6-12 h later during dark cycle when >70% of food intake occurred; glucose transport followed a similar pattern with increased uptake at 9 pm. Conclusion: Hexose transporter expression and function vary diurnally with nocturnal feeding patterns of mice.
KW - Diurnal rhythm
KW - Hexose transporters
KW - Mice
KW - Small intestine
KW - Sugar absorption
UR - http://www.scopus.com/inward/record.url?scp=67349192167&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=67349192167&partnerID=8YFLogxK
U2 - 10.1007/s11605-008-0776-4
DO - 10.1007/s11605-008-0776-4
M3 - Article
C2 - 19082670
AN - SCOPUS:67349192167
VL - 13
SP - 634
EP - 641
JO - Journal of Gastrointestinal Surgery
JF - Journal of Gastrointestinal Surgery
SN - 1091-255X
IS - 4
ER -