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Targeted inactivation of kinesin-1 in pancreatic β-cells in vivo leads to insulin secretory deficiency.

Cui J, Wang Z, Cheng Q, Lin R, Zhang XM, Leung PS, Copeland NG, Jenkins NA, Yao KM, Huang JD - Diabetes (2010)

Bottom Line: In this study, we examined the in vivo physiological role of Kinesin-1 in β-cell development and function.However, compared with controls, pancreas of Kif5b(fl/)⁻:RIP2-Cre mice exhibited both reduced islet size and increased islet number, concomitant with an increased insulin vesicle density in β-cells.In addition to being essential for maintaining glucose homeostasis and regulating β-cell function, Kif5b may be involved in β-cell development by regulating β-cell proliferation and insulin vesicle synthesis.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry, The University of Hong Kong, Hong Kong.

ABSTRACT

Objective: Suppression of Kinesin-1 by antisense oligonucleotides, or overexpression of dominant-negative acting kinesin heavy chain, has been reported to affect the sustained phase of glucose-stimulated insulin secretion in β-cells in vitro. In this study, we examined the in vivo physiological role of Kinesin-1 in β-cell development and function.

Research design and methods: A Cre-LoxP strategy was used to generate conditional knockout mice in which the Kif5b gene is specifically inactivated in pancreatic β-cells. Physiological and histological analyses were carried out in Kif5b knockout mice as well as littermate controls.

Results: Mice with β-cell specific deletion of Kif5b (Kif5b(fl/)⁻:RIP2-Cre) displayed significantly retarded growth as well as slight hyperglycemia in both nonfasting and 16-h fasting conditions compared with control littermates. In addition, Kif5b(fl/)⁻:RIP2-Cre mice displayed significant glucose intolerance, which was not due to insulin resistance but was related to an insulin secretory defect in response to glucose challenge. These defects of β-cell function in mutant mice were not coupled with observable changes in islet morphology, islet cell composition, or β-cell size. However, compared with controls, pancreas of Kif5b(fl/)⁻:RIP2-Cre mice exhibited both reduced islet size and increased islet number, concomitant with an increased insulin vesicle density in β-cells.

Conclusions: In addition to being essential for maintaining glucose homeostasis and regulating β-cell function, Kif5b may be involved in β-cell development by regulating β-cell proliferation and insulin vesicle synthesis.

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Related in: MedlinePlus

Kif5bfl/−:RIP2-Cre mice had normal islet morphology, islet cell composition, and β-cell size. A slight increase in islet insulin content was observed. A: Immunofluorescence staining for insulin (green) and glucagon (red) in control (upper) and mutant mice (lower) (2- to 3-month-old). B: Statistical analysis of α- and β-cell ratio in control (black bar) and mutant (white bar) mice (n = 3 mice per group); immunofluorescent staining was carried out on two sections (>300 μm apart) for α-cell (red) and β-cell (green), and all islets on the sections were imaged. (A high-quality color representation of this figure is available in the online issue.)
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Figure 6: Kif5bfl/−:RIP2-Cre mice had normal islet morphology, islet cell composition, and β-cell size. A slight increase in islet insulin content was observed. A: Immunofluorescence staining for insulin (green) and glucagon (red) in control (upper) and mutant mice (lower) (2- to 3-month-old). B: Statistical analysis of α- and β-cell ratio in control (black bar) and mutant (white bar) mice (n = 3 mice per group); immunofluorescent staining was carried out on two sections (>300 μm apart) for α-cell (red) and β-cell (green), and all islets on the sections were imaged. (A high-quality color representation of this figure is available in the online issue.)

Mentions: To rule out the possibility that insulin is produced at a lower level in the mutant islet than in the wild-type, an immunostaining assay was carried out. The result demonstrated that the insulin level in mutant mouse was not less than that of wild-type control (Fig. 6A). A quantitative analysis of islet insulin content was carried out by ELISA to confirm the result. Results indicated that more insulin accumulated in mutant islets compared with wild-type, although the difference was not statistically significant (Fig. 5F). Taken together, it is most likely that the impaired insulin secretion in mutant mice is due to a primary defect in β-cell function.


Targeted inactivation of kinesin-1 in pancreatic β-cells in vivo leads to insulin secretory deficiency.

Cui J, Wang Z, Cheng Q, Lin R, Zhang XM, Leung PS, Copeland NG, Jenkins NA, Yao KM, Huang JD - Diabetes (2010)

Kif5bfl/−:RIP2-Cre mice had normal islet morphology, islet cell composition, and β-cell size. A slight increase in islet insulin content was observed. A: Immunofluorescence staining for insulin (green) and glucagon (red) in control (upper) and mutant mice (lower) (2- to 3-month-old). B: Statistical analysis of α- and β-cell ratio in control (black bar) and mutant (white bar) mice (n = 3 mice per group); immunofluorescent staining was carried out on two sections (>300 μm apart) for α-cell (red) and β-cell (green), and all islets on the sections were imaged. (A high-quality color representation of this figure is available in the online issue.)
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3012189&req=5

Figure 6: Kif5bfl/−:RIP2-Cre mice had normal islet morphology, islet cell composition, and β-cell size. A slight increase in islet insulin content was observed. A: Immunofluorescence staining for insulin (green) and glucagon (red) in control (upper) and mutant mice (lower) (2- to 3-month-old). B: Statistical analysis of α- and β-cell ratio in control (black bar) and mutant (white bar) mice (n = 3 mice per group); immunofluorescent staining was carried out on two sections (>300 μm apart) for α-cell (red) and β-cell (green), and all islets on the sections were imaged. (A high-quality color representation of this figure is available in the online issue.)
Mentions: To rule out the possibility that insulin is produced at a lower level in the mutant islet than in the wild-type, an immunostaining assay was carried out. The result demonstrated that the insulin level in mutant mouse was not less than that of wild-type control (Fig. 6A). A quantitative analysis of islet insulin content was carried out by ELISA to confirm the result. Results indicated that more insulin accumulated in mutant islets compared with wild-type, although the difference was not statistically significant (Fig. 5F). Taken together, it is most likely that the impaired insulin secretion in mutant mice is due to a primary defect in β-cell function.

Bottom Line: In this study, we examined the in vivo physiological role of Kinesin-1 in β-cell development and function.However, compared with controls, pancreas of Kif5b(fl/)⁻:RIP2-Cre mice exhibited both reduced islet size and increased islet number, concomitant with an increased insulin vesicle density in β-cells.In addition to being essential for maintaining glucose homeostasis and regulating β-cell function, Kif5b may be involved in β-cell development by regulating β-cell proliferation and insulin vesicle synthesis.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry, The University of Hong Kong, Hong Kong.

ABSTRACT

Objective: Suppression of Kinesin-1 by antisense oligonucleotides, or overexpression of dominant-negative acting kinesin heavy chain, has been reported to affect the sustained phase of glucose-stimulated insulin secretion in β-cells in vitro. In this study, we examined the in vivo physiological role of Kinesin-1 in β-cell development and function.

Research design and methods: A Cre-LoxP strategy was used to generate conditional knockout mice in which the Kif5b gene is specifically inactivated in pancreatic β-cells. Physiological and histological analyses were carried out in Kif5b knockout mice as well as littermate controls.

Results: Mice with β-cell specific deletion of Kif5b (Kif5b(fl/)⁻:RIP2-Cre) displayed significantly retarded growth as well as slight hyperglycemia in both nonfasting and 16-h fasting conditions compared with control littermates. In addition, Kif5b(fl/)⁻:RIP2-Cre mice displayed significant glucose intolerance, which was not due to insulin resistance but was related to an insulin secretory defect in response to glucose challenge. These defects of β-cell function in mutant mice were not coupled with observable changes in islet morphology, islet cell composition, or β-cell size. However, compared with controls, pancreas of Kif5b(fl/)⁻:RIP2-Cre mice exhibited both reduced islet size and increased islet number, concomitant with an increased insulin vesicle density in β-cells.

Conclusions: In addition to being essential for maintaining glucose homeostasis and regulating β-cell function, Kif5b may be involved in β-cell development by regulating β-cell proliferation and insulin vesicle synthesis.

Show MeSH
Related in: MedlinePlus