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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

Stimulation with TNF-α increased DPP4 release irrespective of the glucose concentration.Notes: Day 10 3T3-L1 adipocytes grown under the 5.5 (closed columns) and 25 mM glucose conditions (open columns) were stimulated with 10 ng/mL of recombinant TNF-α for 24 hours under serum-free conditions. (A) Intracellular and (B) released DPP4 levels were determined by enzyme-linked immunosorbent assay. *P<0.05, **P<0.01, and †P<0.05 versus (vs) 5.5 mM control, ‡P<0.05 vs 25 mM control. n=3. Furthermore, isolated adipocytes incubated under the 5.5 or 25 mM glucose condition were stimulated with 10 ng/mL TNF-α for 24 hours. (C) Intracellular and (D) released DPP4 levels. *P<0.05, **P<0.01, and †P<0.05 vs 5.5 mM control, ‡P<0.05 vs 25 mM control. n=3. (E) mRNA expression of DPP4 in 3T3-L1 cells after the stimulation with 10 ng/mL TNF-α for 24 hours. The ratios of DPP4 mRNA and PPIA under each glucose concentration were calculated and the control values were set to 1.0. n=3.Abbreviations: AU, arbitrary units; DPP4, dipeptidyl peptidase 4; PPIA, peptidylprolyl isomerase A; TNF-α, tumor necrosis factor-α.
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f5-dmso-7-185: Stimulation with TNF-α increased DPP4 release irrespective of the glucose concentration.Notes: Day 10 3T3-L1 adipocytes grown under the 5.5 (closed columns) and 25 mM glucose conditions (open columns) were stimulated with 10 ng/mL of recombinant TNF-α for 24 hours under serum-free conditions. (A) Intracellular and (B) released DPP4 levels were determined by enzyme-linked immunosorbent assay. *P<0.05, **P<0.01, and †P<0.05 versus (vs) 5.5 mM control, ‡P<0.05 vs 25 mM control. n=3. Furthermore, isolated adipocytes incubated under the 5.5 or 25 mM glucose condition were stimulated with 10 ng/mL TNF-α for 24 hours. (C) Intracellular and (D) released DPP4 levels. *P<0.05, **P<0.01, and †P<0.05 vs 5.5 mM control, ‡P<0.05 vs 25 mM control. n=3. (E) mRNA expression of DPP4 in 3T3-L1 cells after the stimulation with 10 ng/mL TNF-α for 24 hours. The ratios of DPP4 mRNA and PPIA under each glucose concentration were calculated and the control values were set to 1.0. n=3.Abbreviations: AU, arbitrary units; DPP4, dipeptidyl peptidase 4; PPIA, peptidylprolyl isomerase A; TNF-α, tumor necrosis factor-α.

Mentions: Previous studies demonstrated that TNF-α levels were increased in both types of diabetes.22,23 Therefore, we stimulated Day 10 mature 3T3-L1 cells, grown under the 5.5 or 25 mM glucose condition, with 10 ng/mL recombinant TNF-α for 24 hours and determined the released and intracellular levels. The treatment with TNF-α induced the release of DPP4, which was more apparent under the 25 mM glucose condition (Figure 5B); however, the intracellular level of DPP4 was less than that under the 5.5 mM glucose condition (Figure 5A). Similar results were obtained when isolated adipocytes from mice incubated under the 5.5 and 25 mM glucose conditions were stimulated with 10 ng/mL TNF-α. TNF-α markedly increased the release of DPP4 under the 25 mM glucose condition than under the 5.5 mM glucose condition (Figure 5D), while intracellular levels remained unaffected (Figure 5C). No significant change was observed in the expression of DPP4 mRNA when adipocytes were stimulated with recombinant TNF-α (Figure 5E).


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)

Stimulation with TNF-α increased DPP4 release irrespective of the glucose concentration.Notes: Day 10 3T3-L1 adipocytes grown under the 5.5 (closed columns) and 25 mM glucose conditions (open columns) were stimulated with 10 ng/mL of recombinant TNF-α for 24 hours under serum-free conditions. (A) Intracellular and (B) released DPP4 levels were determined by enzyme-linked immunosorbent assay. *P<0.05, **P<0.01, and †P<0.05 versus (vs) 5.5 mM control, ‡P<0.05 vs 25 mM control. n=3. Furthermore, isolated adipocytes incubated under the 5.5 or 25 mM glucose condition were stimulated with 10 ng/mL TNF-α for 24 hours. (C) Intracellular and (D) released DPP4 levels. *P<0.05, **P<0.01, and †P<0.05 vs 5.5 mM control, ‡P<0.05 vs 25 mM control. n=3. (E) mRNA expression of DPP4 in 3T3-L1 cells after the stimulation with 10 ng/mL TNF-α for 24 hours. The ratios of DPP4 mRNA and PPIA under each glucose concentration were calculated and the control values were set to 1.0. n=3.Abbreviations: AU, arbitrary units; DPP4, dipeptidyl peptidase 4; PPIA, peptidylprolyl isomerase A; TNF-α, tumor necrosis factor-α.
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Related In: Results  -  Collection

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f5-dmso-7-185: Stimulation with TNF-α increased DPP4 release irrespective of the glucose concentration.Notes: Day 10 3T3-L1 adipocytes grown under the 5.5 (closed columns) and 25 mM glucose conditions (open columns) were stimulated with 10 ng/mL of recombinant TNF-α for 24 hours under serum-free conditions. (A) Intracellular and (B) released DPP4 levels were determined by enzyme-linked immunosorbent assay. *P<0.05, **P<0.01, and †P<0.05 versus (vs) 5.5 mM control, ‡P<0.05 vs 25 mM control. n=3. Furthermore, isolated adipocytes incubated under the 5.5 or 25 mM glucose condition were stimulated with 10 ng/mL TNF-α for 24 hours. (C) Intracellular and (D) released DPP4 levels. *P<0.05, **P<0.01, and †P<0.05 vs 5.5 mM control, ‡P<0.05 vs 25 mM control. n=3. (E) mRNA expression of DPP4 in 3T3-L1 cells after the stimulation with 10 ng/mL TNF-α for 24 hours. The ratios of DPP4 mRNA and PPIA under each glucose concentration were calculated and the control values were set to 1.0. n=3.Abbreviations: AU, arbitrary units; DPP4, dipeptidyl peptidase 4; PPIA, peptidylprolyl isomerase A; TNF-α, tumor necrosis factor-α.
Mentions: Previous studies demonstrated that TNF-α levels were increased in both types of diabetes.22,23 Therefore, we stimulated Day 10 mature 3T3-L1 cells, grown under the 5.5 or 25 mM glucose condition, with 10 ng/mL recombinant TNF-α for 24 hours and determined the released and intracellular levels. The treatment with TNF-α induced the release of DPP4, which was more apparent under the 25 mM glucose condition (Figure 5B); however, the intracellular level of DPP4 was less than that under the 5.5 mM glucose condition (Figure 5A). Similar results were obtained when isolated adipocytes from mice incubated under the 5.5 and 25 mM glucose conditions were stimulated with 10 ng/mL TNF-α. TNF-α markedly increased the release of DPP4 under the 25 mM glucose condition than under the 5.5 mM glucose condition (Figure 5D), while intracellular levels remained unaffected (Figure 5C). No significant change was observed in the expression of DPP4 mRNA when adipocytes were stimulated with recombinant TNF-α (Figure 5E).

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