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Bacterial metabolite indole modulates incretin secretion from intestinal enteroendocrine L cells.

Chimerel C, Emery E, Summers DK, Keyser U, Gribble FM, Reimann F - Cell Rep (2014)

Bottom Line: These effects were attributed to the ability of indole to affect two key molecular mechanisms in L cells.On the other hand, indole slowed ATP production by blocking NADH dehydrogenase, thus leading to a prolonged reduction of GLP-1 secretion.Our results identify indole as a signaling molecule by which gut microbiota communicate with L cells and influence host metabolism.

View Article: PubMed Central - PubMed

Affiliation: Institute of Metabolic Science and MRC Metabolic Diseases Unit, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK; Cavendish Laboratory, Department of Physics, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK. Electronic address: cc539@cam.ac.uk.

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Modulation of GLP-1 Secretion in GLUTag Cells by Indole(A) Cumulative GLP-1 secretion from GLUTag cells stimulated with 1 mM glucose, measured at different time points. Cells were incubated with and without 1 mM indole, and secretion was normalized to the 60 min, 1 mM glucose, time point (average value of 15 pg/ml) from the same experiment. Each data point was calculated by averaging over eight or more independent measurements. Significance was calculated at specific time points comparing the secretion at 1 mM glucose and the secretion at 1 mM glucose + 1 mM indole.(B) Calculated rates of GLP-1 secretion over the time periods indicated, calculated from the data in (A). a.u., arbitrary units.(C) GLP-1 secretion measured in response to different indole concentrations for an incubation time of 6 min in the presence of 1 mM glucose (measured from three independent measurements). To gain resolution the data were measured on a plate with high cell density (45 pg/ml GLP-1 secreted after 6 min in 1 mM glucose).(D) GLP-1 secretion measured in response to different indole concentration for an incubation time of 240 min on a plate with high cell density (measured from three independent measurements). Data are presented as mean ± SEM. *p < 0.05, **p < 0.01, ***p < 0.001 by paired Student’s t test. The lines between points are drawn to guide the eye.
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Figure 1: Modulation of GLP-1 Secretion in GLUTag Cells by Indole(A) Cumulative GLP-1 secretion from GLUTag cells stimulated with 1 mM glucose, measured at different time points. Cells were incubated with and without 1 mM indole, and secretion was normalized to the 60 min, 1 mM glucose, time point (average value of 15 pg/ml) from the same experiment. Each data point was calculated by averaging over eight or more independent measurements. Significance was calculated at specific time points comparing the secretion at 1 mM glucose and the secretion at 1 mM glucose + 1 mM indole.(B) Calculated rates of GLP-1 secretion over the time periods indicated, calculated from the data in (A). a.u., arbitrary units.(C) GLP-1 secretion measured in response to different indole concentrations for an incubation time of 6 min in the presence of 1 mM glucose (measured from three independent measurements). To gain resolution the data were measured on a plate with high cell density (45 pg/ml GLP-1 secreted after 6 min in 1 mM glucose).(D) GLP-1 secretion measured in response to different indole concentration for an incubation time of 240 min on a plate with high cell density (measured from three independent measurements). Data are presented as mean ± SEM. *p < 0.05, **p < 0.01, ***p < 0.001 by paired Student’s t test. The lines between points are drawn to guide the eye.

Mentions: Cumulative GLP-1 secretion from GLUTag cells was measured in the presence of saline buffer containing 1 mM glucose and 0.1% (wt/vol) BSA over 240 min (Figure 1A). The GLP-1 concentration in the medium increased approximately linearly with time under these conditions, reflecting a relatively constant GLP-1 secretory rate (Figure 1B). In the additional presence of 1 mM indole, GLP-1 secretion was modified over both short and long time periods. Very high GLP-1 concentrations were measured in the medium of indole-treated cells after only 5 min, indicating a rapid initial stimulation of secretion (Figures 1A and 1B). Thereafter, GLP-1 concentrations continued to rise, but the rate of release was slower than that observed in the absence of indole (Figure 1B). At the end of the 240 min incubation period, cumulative released GLP-1 was ~35% less in the presence of 1 mM indole than in its absence. These data indicate that although indole acutely stimulates GLP-1 secretion, it exerts a suppressive effect on the rate of hormone release over prolonged time periods. We examined the dose dependence of indole on both the short- and long-term actions by measuring cumulative GLP-1 release after 6 and 240 min incubations (Figures 1C and 1D). After 6 min, the acute stimulatory effect of indole was evident at concentrations above 1 mM. After 240 min, by contrast, the suppressive effect was evident at indole concentrations as low as 0.3 mM. To clarify the interaction between indole and GLUTag cells, we investigated the molecular mechanisms that determine the modulation of GLP-1 secretion by indole.


Bacterial metabolite indole modulates incretin secretion from intestinal enteroendocrine L cells.

Chimerel C, Emery E, Summers DK, Keyser U, Gribble FM, Reimann F - Cell Rep (2014)

Modulation of GLP-1 Secretion in GLUTag Cells by Indole(A) Cumulative GLP-1 secretion from GLUTag cells stimulated with 1 mM glucose, measured at different time points. Cells were incubated with and without 1 mM indole, and secretion was normalized to the 60 min, 1 mM glucose, time point (average value of 15 pg/ml) from the same experiment. Each data point was calculated by averaging over eight or more independent measurements. Significance was calculated at specific time points comparing the secretion at 1 mM glucose and the secretion at 1 mM glucose + 1 mM indole.(B) Calculated rates of GLP-1 secretion over the time periods indicated, calculated from the data in (A). a.u., arbitrary units.(C) GLP-1 secretion measured in response to different indole concentrations for an incubation time of 6 min in the presence of 1 mM glucose (measured from three independent measurements). To gain resolution the data were measured on a plate with high cell density (45 pg/ml GLP-1 secreted after 6 min in 1 mM glucose).(D) GLP-1 secretion measured in response to different indole concentration for an incubation time of 240 min on a plate with high cell density (measured from three independent measurements). Data are presented as mean ± SEM. *p < 0.05, **p < 0.01, ***p < 0.001 by paired Student’s t test. The lines between points are drawn to guide the eye.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4308618&req=5

Figure 1: Modulation of GLP-1 Secretion in GLUTag Cells by Indole(A) Cumulative GLP-1 secretion from GLUTag cells stimulated with 1 mM glucose, measured at different time points. Cells were incubated with and without 1 mM indole, and secretion was normalized to the 60 min, 1 mM glucose, time point (average value of 15 pg/ml) from the same experiment. Each data point was calculated by averaging over eight or more independent measurements. Significance was calculated at specific time points comparing the secretion at 1 mM glucose and the secretion at 1 mM glucose + 1 mM indole.(B) Calculated rates of GLP-1 secretion over the time periods indicated, calculated from the data in (A). a.u., arbitrary units.(C) GLP-1 secretion measured in response to different indole concentrations for an incubation time of 6 min in the presence of 1 mM glucose (measured from three independent measurements). To gain resolution the data were measured on a plate with high cell density (45 pg/ml GLP-1 secreted after 6 min in 1 mM glucose).(D) GLP-1 secretion measured in response to different indole concentration for an incubation time of 240 min on a plate with high cell density (measured from three independent measurements). Data are presented as mean ± SEM. *p < 0.05, **p < 0.01, ***p < 0.001 by paired Student’s t test. The lines between points are drawn to guide the eye.
Mentions: Cumulative GLP-1 secretion from GLUTag cells was measured in the presence of saline buffer containing 1 mM glucose and 0.1% (wt/vol) BSA over 240 min (Figure 1A). The GLP-1 concentration in the medium increased approximately linearly with time under these conditions, reflecting a relatively constant GLP-1 secretory rate (Figure 1B). In the additional presence of 1 mM indole, GLP-1 secretion was modified over both short and long time periods. Very high GLP-1 concentrations were measured in the medium of indole-treated cells after only 5 min, indicating a rapid initial stimulation of secretion (Figures 1A and 1B). Thereafter, GLP-1 concentrations continued to rise, but the rate of release was slower than that observed in the absence of indole (Figure 1B). At the end of the 240 min incubation period, cumulative released GLP-1 was ~35% less in the presence of 1 mM indole than in its absence. These data indicate that although indole acutely stimulates GLP-1 secretion, it exerts a suppressive effect on the rate of hormone release over prolonged time periods. We examined the dose dependence of indole on both the short- and long-term actions by measuring cumulative GLP-1 release after 6 and 240 min incubations (Figures 1C and 1D). After 6 min, the acute stimulatory effect of indole was evident at concentrations above 1 mM. After 240 min, by contrast, the suppressive effect was evident at indole concentrations as low as 0.3 mM. To clarify the interaction between indole and GLUTag cells, we investigated the molecular mechanisms that determine the modulation of GLP-1 secretion by indole.

Bottom Line: These effects were attributed to the ability of indole to affect two key molecular mechanisms in L cells.On the other hand, indole slowed ATP production by blocking NADH dehydrogenase, thus leading to a prolonged reduction of GLP-1 secretion.Our results identify indole as a signaling molecule by which gut microbiota communicate with L cells and influence host metabolism.

View Article: PubMed Central - PubMed

Affiliation: Institute of Metabolic Science and MRC Metabolic Diseases Unit, University of Cambridge, Addenbrooke's Hospital, Hills Road, Cambridge CB2 0QQ, UK; Cavendish Laboratory, Department of Physics, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK. Electronic address: cc539@cam.ac.uk.

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Related in: MedlinePlus