Limits...
Regulation of dipeptidyl peptidase 4 production in adipocytes by glucose.

Das SS, Hayashi H, Sato T, Yamada R, Hiratsuka M, Hirasawa N - Diabetes Metab Syndr Obes (2014)

Bottom Line: However, this difference gradually disappeared over 6 weeks.The stimulation of adipocytes with TNF-α increased the release of DPP4 irrespective of glucose concentration.Our results suggest that the observed increase in serum DPP4 levels may be attributed to increased production of DPP4 in adipocytes and an enhancement in TNF-α-induced release.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Pharmacotherapy of Life-Style Related Diseases, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi, Japan.

ABSTRACT

Objective: Type 1 and 2 diabetes are characterized by elevated blood glucose levels and increased dipeptidyl peptidase 4 (DPP4) activity levels in the serum. However, previous studies reported a negative correlation between glucose concentrations and DPP4 levels. The purpose of this study was to elucidate the connection between glucose and DPP4 in adipocytes under physiological and diabetic conditions, because DPP4 is an adipokine.

Methods: Blood glucose and serum DPP4 levels were measured, and adipocytes were collected from mice under normal, high-fat diet fed, and diabetic conditions. The adipocytes obtained were incubated for 24 hours in medium containing 5.5 or 25 mM glucose, and 3T3-L1 preadipocytes were differentiated under 5.5 or 25 mM glucose. Adipocytes from mice and 3T3-L1 were stimulated by tumor necrosis factor-α (TNF-α) for 24 hours. The levels of released and intracellular DPP4 were determined by enzyme-linked immunosorbent assay.

Results: Mice fed high-fat diet had lower serum DPP4 levels in the first and second week than controls. However, this difference gradually disappeared over 6 weeks. The differentiation of 3T3-L1 adipocytes under 25 mM glucose produced lower DPP4 levels than those differentiated under 5.5 mM; this was also observed in isolated adipocytes from mice. However, these effects of glucose were lost in adipocytes from diabetic mice, and an increase in total DPP4 levels was observed. The stimulation of adipocytes with TNF-α increased the release of DPP4 irrespective of glucose concentration.

Conclusion: The production of DPP4 in adipocytes was negatively regulated by 25 mM glucose under physiological conditions, but not in diabetic mice. Our results suggest that the observed increase in serum DPP4 levels may be attributed to increased production of DPP4 in adipocytes and an enhancement in TNF-α-induced release.

No MeSH data available.


Related in: MedlinePlus

Intracellular, released, and mRNA expression of DPP4.Notes: Changes in (A) intracellular and (B) released DPP4 protein levels during 3T3-L1 differentiation were determined. Intracellular DPP4 levels were adjusted to total protein levels from differentiating 3T3-L1 cells. Closed bars represent adipocytes cultured in 5.5 mM glucose, while open bars represent those grown in 25 mM glucose. n=4. **P<0.01 and ‡‡P<0.01 versus (vs) preadipocytes (Day 0); ††P<0.01 and †††P<0.001 between 5.5 and 25 mM glucose. (B) Released DPP4 levels from Day 10 adipocytes during the 24-hour incubation in serum-free 5.5 or 25 mM glucose DMEM. n=4. §§§P<0.001. (C) Expression of DPP4, DPP8, and DPP9 mRNA in 3T3-L1 preadipocytes and Day 6 adipocytes. n=4. The ratio of each DPP and PPIA was calculated and the value of preadipocytes was set to 1.0. Closed bars represent adipocytes grown in 5.5 mM glucose, while open bars represent those grown in 25 mM glucose. ‡P<0.05 and **P<0.01 vs preadipocytes. †P<0.05, ††P<0.01 between 5.5 mM and 25 mM glucose.Abbreviations: AU, arbitrary units; DPP4, dipeptidyl peptidase 4; DPP8, dipeptidyl peptidase 8; DPP9, dipeptidyl peptidase 9; mRNA, messenger ribonucleic acid; PPIA, peptidylprolyl isomerase A.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4043708&req=5

f3-dmso-7-185: Intracellular, released, and mRNA expression of DPP4.Notes: Changes in (A) intracellular and (B) released DPP4 protein levels during 3T3-L1 differentiation were determined. Intracellular DPP4 levels were adjusted to total protein levels from differentiating 3T3-L1 cells. Closed bars represent adipocytes cultured in 5.5 mM glucose, while open bars represent those grown in 25 mM glucose. n=4. **P<0.01 and ‡‡P<0.01 versus (vs) preadipocytes (Day 0); ††P<0.01 and †††P<0.001 between 5.5 and 25 mM glucose. (B) Released DPP4 levels from Day 10 adipocytes during the 24-hour incubation in serum-free 5.5 or 25 mM glucose DMEM. n=4. §§§P<0.001. (C) Expression of DPP4, DPP8, and DPP9 mRNA in 3T3-L1 preadipocytes and Day 6 adipocytes. n=4. The ratio of each DPP and PPIA was calculated and the value of preadipocytes was set to 1.0. Closed bars represent adipocytes grown in 5.5 mM glucose, while open bars represent those grown in 25 mM glucose. ‡P<0.05 and **P<0.01 vs preadipocytes. †P<0.05, ††P<0.01 between 5.5 mM and 25 mM glucose.Abbreviations: AU, arbitrary units; DPP4, dipeptidyl peptidase 4; DPP8, dipeptidyl peptidase 8; DPP9, dipeptidyl peptidase 9; mRNA, messenger ribonucleic acid; PPIA, peptidylprolyl isomerase A.

Mentions: We then assessed intracellular DPP4 levels in differentiating 3T3-L1 cells for 14 days, and found that DPP4 levels increased with differentiation. Adipocytes cultured under the 25 mM glucose condition produced less intracellular DPP4 than adipocytes cultured under the 5.5 mM glucose condition, as determined by enzyme-linked immunosorbent assay (Figure 3A). The release of DPP4 from Day 10 3T3-L1 adipocytes incubated under the serum-free 25 mM glucose condition was also less than that from adipocytes incubated under the 5.5 mM glucose condition (Figure 3B). These results indicated that the difference observed in intracellular DPP4 levels was not due to the enhanced release of DPP4.


Regulation of dipeptidyl peptidase 4 production in adipocytes by glucose.

Das SS, Hayashi H, Sato T, Yamada R, Hiratsuka M, Hirasawa N - Diabetes Metab Syndr Obes (2014)

Intracellular, released, and mRNA expression of DPP4.Notes: Changes in (A) intracellular and (B) released DPP4 protein levels during 3T3-L1 differentiation were determined. Intracellular DPP4 levels were adjusted to total protein levels from differentiating 3T3-L1 cells. Closed bars represent adipocytes cultured in 5.5 mM glucose, while open bars represent those grown in 25 mM glucose. n=4. **P<0.01 and ‡‡P<0.01 versus (vs) preadipocytes (Day 0); ††P<0.01 and †††P<0.001 between 5.5 and 25 mM glucose. (B) Released DPP4 levels from Day 10 adipocytes during the 24-hour incubation in serum-free 5.5 or 25 mM glucose DMEM. n=4. §§§P<0.001. (C) Expression of DPP4, DPP8, and DPP9 mRNA in 3T3-L1 preadipocytes and Day 6 adipocytes. n=4. The ratio of each DPP and PPIA was calculated and the value of preadipocytes was set to 1.0. Closed bars represent adipocytes grown in 5.5 mM glucose, while open bars represent those grown in 25 mM glucose. ‡P<0.05 and **P<0.01 vs preadipocytes. †P<0.05, ††P<0.01 between 5.5 mM and 25 mM glucose.Abbreviations: AU, arbitrary units; DPP4, dipeptidyl peptidase 4; DPP8, dipeptidyl peptidase 8; DPP9, dipeptidyl peptidase 9; mRNA, messenger ribonucleic acid; PPIA, peptidylprolyl isomerase A.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4043708&req=5

f3-dmso-7-185: Intracellular, released, and mRNA expression of DPP4.Notes: Changes in (A) intracellular and (B) released DPP4 protein levels during 3T3-L1 differentiation were determined. Intracellular DPP4 levels were adjusted to total protein levels from differentiating 3T3-L1 cells. Closed bars represent adipocytes cultured in 5.5 mM glucose, while open bars represent those grown in 25 mM glucose. n=4. **P<0.01 and ‡‡P<0.01 versus (vs) preadipocytes (Day 0); ††P<0.01 and †††P<0.001 between 5.5 and 25 mM glucose. (B) Released DPP4 levels from Day 10 adipocytes during the 24-hour incubation in serum-free 5.5 or 25 mM glucose DMEM. n=4. §§§P<0.001. (C) Expression of DPP4, DPP8, and DPP9 mRNA in 3T3-L1 preadipocytes and Day 6 adipocytes. n=4. The ratio of each DPP and PPIA was calculated and the value of preadipocytes was set to 1.0. Closed bars represent adipocytes grown in 5.5 mM glucose, while open bars represent those grown in 25 mM glucose. ‡P<0.05 and **P<0.01 vs preadipocytes. †P<0.05, ††P<0.01 between 5.5 mM and 25 mM glucose.Abbreviations: AU, arbitrary units; DPP4, dipeptidyl peptidase 4; DPP8, dipeptidyl peptidase 8; DPP9, dipeptidyl peptidase 9; mRNA, messenger ribonucleic acid; PPIA, peptidylprolyl isomerase A.
Mentions: We then assessed intracellular DPP4 levels in differentiating 3T3-L1 cells for 14 days, and found that DPP4 levels increased with differentiation. Adipocytes cultured under the 25 mM glucose condition produced less intracellular DPP4 than adipocytes cultured under the 5.5 mM glucose condition, as determined by enzyme-linked immunosorbent assay (Figure 3A). The release of DPP4 from Day 10 3T3-L1 adipocytes incubated under the serum-free 25 mM glucose condition was also less than that from adipocytes incubated under the 5.5 mM glucose condition (Figure 3B). These results indicated that the difference observed in intracellular DPP4 levels was not due to the enhanced release of DPP4.

Bottom Line: However, this difference gradually disappeared over 6 weeks.The stimulation of adipocytes with TNF-α increased the release of DPP4 irrespective of glucose concentration.Our results suggest that the observed increase in serum DPP4 levels may be attributed to increased production of DPP4 in adipocytes and an enhancement in TNF-α-induced release.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Pharmacotherapy of Life-Style Related Diseases, Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi, Japan.

ABSTRACT

Objective: Type 1 and 2 diabetes are characterized by elevated blood glucose levels and increased dipeptidyl peptidase 4 (DPP4) activity levels in the serum. However, previous studies reported a negative correlation between glucose concentrations and DPP4 levels. The purpose of this study was to elucidate the connection between glucose and DPP4 in adipocytes under physiological and diabetic conditions, because DPP4 is an adipokine.

Methods: Blood glucose and serum DPP4 levels were measured, and adipocytes were collected from mice under normal, high-fat diet fed, and diabetic conditions. The adipocytes obtained were incubated for 24 hours in medium containing 5.5 or 25 mM glucose, and 3T3-L1 preadipocytes were differentiated under 5.5 or 25 mM glucose. Adipocytes from mice and 3T3-L1 were stimulated by tumor necrosis factor-α (TNF-α) for 24 hours. The levels of released and intracellular DPP4 were determined by enzyme-linked immunosorbent assay.

Results: Mice fed high-fat diet had lower serum DPP4 levels in the first and second week than controls. However, this difference gradually disappeared over 6 weeks. The differentiation of 3T3-L1 adipocytes under 25 mM glucose produced lower DPP4 levels than those differentiated under 5.5 mM; this was also observed in isolated adipocytes from mice. However, these effects of glucose were lost in adipocytes from diabetic mice, and an increase in total DPP4 levels was observed. The stimulation of adipocytes with TNF-α increased the release of DPP4 irrespective of glucose concentration.

Conclusion: The production of DPP4 in adipocytes was negatively regulated by 25 mM glucose under physiological conditions, but not in diabetic mice. Our results suggest that the observed increase in serum DPP4 levels may be attributed to increased production of DPP4 in adipocytes and an enhancement in TNF-α-induced release.

No MeSH data available.


Related in: MedlinePlus