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Effects of E2HSA, a Long-Acting Glucagon Like Peptide-1 Receptor Agonist, on Glycemic Control and Beta Cell Function in Spontaneous Diabetic db/db Mice.

Hou S, Li C, Huan Y, Liu S, Liu Q, Sun S, Jiang Q, Jia C, Shen Z - J Diabetes Res (2015)

Bottom Line: Chronic E2HSA treatment in db/db mice significantly improved glucose tolerance, reduced elevated nonfasting and fasting plasma glucose levels, and also decreased HbA1c levels.Furthermore, immunofluorescence analysis showed that E2HSA increased β-cell area, improved islet morphology, and reduced β-cell apoptosis.In conclusion, with prolonged glucose lowering effects and promoting β-cell function and survival, the fusion protein, E2HSA, is a promising new therapeutic for once weekly treatment of type 2 diabetes.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China.

ABSTRACT
Glucagon like peptide-1 (GLP-1) receptor agonists such as exendin-4 have been widely used but their short half-life limits their therapeutic value. The recombinant protein, E2HSA, is a novel, long-acting GLP-1 receptor agonist generated by the fusion of exendin-4 with human serum albumin. In mouse pancreatic NIT-1 cells, E2HSA activated GLP-1 receptor with similar efficacy as exendin-4. After single-dose administration in ICR mice, E2HSA showed prolonged glucose lowering effects which lasted up to four days and extended inhibition on gastric emptying for at least 72 hours. Chronic E2HSA treatment in db/db mice significantly improved glucose tolerance, reduced elevated nonfasting and fasting plasma glucose levels, and also decreased HbA1c levels. E2HSA also increased insulin secretion and decreased body weight and appetite. Furthermore, immunofluorescence analysis showed that E2HSA increased β-cell area, improved islet morphology, and reduced β-cell apoptosis. In accordance with the promotion of β-cell function and survival, E2HSA upregulated genes such as Irs2, Pdx-1, Nkx6.1, and MafA and downregulated the expression levels of FoxO1 and proapoptotic Bcl-2 family proteins. In conclusion, with prolonged glucose lowering effects and promoting β-cell function and survival, the fusion protein, E2HSA, is a promising new therapeutic for once weekly treatment of type 2 diabetes.

No MeSH data available.


Related in: MedlinePlus

Expression of genes related to β-cell function and survival in spontaneous type 2 diabetes db/db mice treated with E2HSA. Data were from pancreas tail samples. Gene expression was analyzed by quantitative real-time PCR. A comparative cycle threshold (CT) method was used for relative quantification of gene expression between different groups using β-actin for normalization. Data are expressed as mean ± S.E.M (n = 4-5). ∗P < 0.05 and ∗∗P < 0.01 versus Con.
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fig8: Expression of genes related to β-cell function and survival in spontaneous type 2 diabetes db/db mice treated with E2HSA. Data were from pancreas tail samples. Gene expression was analyzed by quantitative real-time PCR. A comparative cycle threshold (CT) method was used for relative quantification of gene expression between different groups using β-actin for normalization. Data are expressed as mean ± S.E.M (n = 4-5). ∗P < 0.05 and ∗∗P < 0.01 versus Con.

Mentions: Since chronic E2HSA treatment significantly increased β-cell area in db/db mice, we next used quantitative real-time PCR and Western blot to investigate whether the expressions of genes and proteins associated with β-cell survival and apoptosis were affected by E2HSA using samples made from the pancreas tail section. As shown in Figure 8, expression of Irs2, an essential component of the GLP-1 and insulin signaling pathways, was increased by 1.8-fold and 1.7-fold in E2HSA (9 mg/kg) and exendin-4 treated groups, respectively. Another downstream target of GLP-1, Pdx-1, was also upregulated by E2HSA (9 mg/kg). Bcl-2 family proteins are critical to β-cell survival and linked to GLP-1R activation. The proapoptotic factors, BAD and Bim, interact with Bcl-XL/Bcl-2 and result in cell death, while phosphorylated BAD (pBAD) is the inactive form and thus correlates with less death. We have demonstrated that E2HSA (9 mg/kg) treatment significantly increased pBAD (Ser112)/BAD ratios and decreased Bim expression levels (Figures 9(a)-9(b)), whereas prosurvival Bcl-XL protein expression levels were significantly upregulated and expression of Bcl-2 displayed a tendency towards enhancement (Figures 9(c)-9(d)). At the same time, E2HSA treatment also promoted the phosphorylation of an upstream regulator of BAD, Erk1/2, which phosphorylates BAD at Ser112, thus further reducing proapoptotic signals (Figure 9(e)). FoxO1 plays an important role in β-cell apoptosis and phosphorylation of FoxO1 leads to its inactivation. After chronic treatment with E2HSA, the pFoxO1/FoxO1 ratio was greatly augmented in db/db mice islets, indicating its activity was inhibited (Figure 9(f)). In accordance with increased insulin secretion, the expression levels of two important genes involved in the regulation of insulin biosynthesis and secretion, Nkx6.1 and MafA, were both significantly increased by about 1.8-fold after E2HSA treatment (Figure 8). E2HSA also upregulated Ins2 and Igf1, two genes which are involved in insulin-induced signaling pathways.


Effects of E2HSA, a Long-Acting Glucagon Like Peptide-1 Receptor Agonist, on Glycemic Control and Beta Cell Function in Spontaneous Diabetic db/db Mice.

Hou S, Li C, Huan Y, Liu S, Liu Q, Sun S, Jiang Q, Jia C, Shen Z - J Diabetes Res (2015)

Expression of genes related to β-cell function and survival in spontaneous type 2 diabetes db/db mice treated with E2HSA. Data were from pancreas tail samples. Gene expression was analyzed by quantitative real-time PCR. A comparative cycle threshold (CT) method was used for relative quantification of gene expression between different groups using β-actin for normalization. Data are expressed as mean ± S.E.M (n = 4-5). ∗P < 0.05 and ∗∗P < 0.01 versus Con.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4553314&req=5

fig8: Expression of genes related to β-cell function and survival in spontaneous type 2 diabetes db/db mice treated with E2HSA. Data were from pancreas tail samples. Gene expression was analyzed by quantitative real-time PCR. A comparative cycle threshold (CT) method was used for relative quantification of gene expression between different groups using β-actin for normalization. Data are expressed as mean ± S.E.M (n = 4-5). ∗P < 0.05 and ∗∗P < 0.01 versus Con.
Mentions: Since chronic E2HSA treatment significantly increased β-cell area in db/db mice, we next used quantitative real-time PCR and Western blot to investigate whether the expressions of genes and proteins associated with β-cell survival and apoptosis were affected by E2HSA using samples made from the pancreas tail section. As shown in Figure 8, expression of Irs2, an essential component of the GLP-1 and insulin signaling pathways, was increased by 1.8-fold and 1.7-fold in E2HSA (9 mg/kg) and exendin-4 treated groups, respectively. Another downstream target of GLP-1, Pdx-1, was also upregulated by E2HSA (9 mg/kg). Bcl-2 family proteins are critical to β-cell survival and linked to GLP-1R activation. The proapoptotic factors, BAD and Bim, interact with Bcl-XL/Bcl-2 and result in cell death, while phosphorylated BAD (pBAD) is the inactive form and thus correlates with less death. We have demonstrated that E2HSA (9 mg/kg) treatment significantly increased pBAD (Ser112)/BAD ratios and decreased Bim expression levels (Figures 9(a)-9(b)), whereas prosurvival Bcl-XL protein expression levels were significantly upregulated and expression of Bcl-2 displayed a tendency towards enhancement (Figures 9(c)-9(d)). At the same time, E2HSA treatment also promoted the phosphorylation of an upstream regulator of BAD, Erk1/2, which phosphorylates BAD at Ser112, thus further reducing proapoptotic signals (Figure 9(e)). FoxO1 plays an important role in β-cell apoptosis and phosphorylation of FoxO1 leads to its inactivation. After chronic treatment with E2HSA, the pFoxO1/FoxO1 ratio was greatly augmented in db/db mice islets, indicating its activity was inhibited (Figure 9(f)). In accordance with increased insulin secretion, the expression levels of two important genes involved in the regulation of insulin biosynthesis and secretion, Nkx6.1 and MafA, were both significantly increased by about 1.8-fold after E2HSA treatment (Figure 8). E2HSA also upregulated Ins2 and Igf1, two genes which are involved in insulin-induced signaling pathways.

Bottom Line: Chronic E2HSA treatment in db/db mice significantly improved glucose tolerance, reduced elevated nonfasting and fasting plasma glucose levels, and also decreased HbA1c levels.Furthermore, immunofluorescence analysis showed that E2HSA increased β-cell area, improved islet morphology, and reduced β-cell apoptosis.In conclusion, with prolonged glucose lowering effects and promoting β-cell function and survival, the fusion protein, E2HSA, is a promising new therapeutic for once weekly treatment of type 2 diabetes.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100050, China.

ABSTRACT
Glucagon like peptide-1 (GLP-1) receptor agonists such as exendin-4 have been widely used but their short half-life limits their therapeutic value. The recombinant protein, E2HSA, is a novel, long-acting GLP-1 receptor agonist generated by the fusion of exendin-4 with human serum albumin. In mouse pancreatic NIT-1 cells, E2HSA activated GLP-1 receptor with similar efficacy as exendin-4. After single-dose administration in ICR mice, E2HSA showed prolonged glucose lowering effects which lasted up to four days and extended inhibition on gastric emptying for at least 72 hours. Chronic E2HSA treatment in db/db mice significantly improved glucose tolerance, reduced elevated nonfasting and fasting plasma glucose levels, and also decreased HbA1c levels. E2HSA also increased insulin secretion and decreased body weight and appetite. Furthermore, immunofluorescence analysis showed that E2HSA increased β-cell area, improved islet morphology, and reduced β-cell apoptosis. In accordance with the promotion of β-cell function and survival, E2HSA upregulated genes such as Irs2, Pdx-1, Nkx6.1, and MafA and downregulated the expression levels of FoxO1 and proapoptotic Bcl-2 family proteins. In conclusion, with prolonged glucose lowering effects and promoting β-cell function and survival, the fusion protein, E2HSA, is a promising new therapeutic for once weekly treatment of type 2 diabetes.

No MeSH data available.


Related in: MedlinePlus