Apolipoprotein A-V modulates insulin secretion in pancreatic beta-cells through its interaction with midkine.
Apolipoprotein A-V is an important determinant of plasma triglyceride level in both humans and mice. This study showed the physiological impact of apoA-V on insulin secretion in rat pancreatic beta-cells (INS-1 cells). In order to precise the mechanism of action, binding experiments coupled to mass spectrometry were performed to identify a potential membrane receptor. Results showed an interaction between apoA-V and midkine protein. Confocal microscopy confirmed the plasma membrane co-localisation of this two-proteins after the treatment of INS-1 cells with the apo-AV recombinant protein and indicated that the cell surface midkine could be involved in apoA-V endocytosis, since these two proteins were co-translocated at the plasma membrane or in the cytosol compartment. This co-localisation is correlated with an increase in insulin secretion in a dose dependant manner during short incubation period. Reduction of midkine expression by small interfering RNA duplexes revealed a decrease in the ability of these transfected cells to secrete insulin in presence of apoA-V. Competition experiments for the apoA-V-midkine binding at the cell surface using antibody directed against midkine is able to influence INS-1 cell function as insulin secretion. Our results showed apoA-V ability to enhance insulin secretion in beta-cells and provide evidence of an internalization pathway involving the midkine as partner.
Helleboid-Chapman
Audrey
A
Université Lille Nord de France, Inserm, UDSL and Institut Pasteur de Lille, France. audrey.helleboid@univ-lille2.fr
Nowak
Maxime
M
Helleboid
Stéphane
S
Moitrot
Emmanuelle
E
Rommens
Corinne
C
Dehondt
Hélène
H
Héliot
Laurent
L
Drobecq
Hervé
H
Fruchart-Najib
Jamila
J
Fruchart
Jean-Charles
JC
D000595:Amino Acid Sequence; D000818:Animals; D000072040:Apolipoprotein A-V; D001053:Apolipoproteins / Q000032:analysis / Q000378:metabolism*; D045744:Cell Line, Tumor; D016207:Cytokines / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D004705:Endocytosis; D047468:Immunoprecipitation; D007328:Insulin / Q000378:metabolism*; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000378:metabolism*; D000078792:Midkine; D008969:Molecular Sequence Data; D011485:Protein Binding; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism / Q000494:pharmacology; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
C514818:Apoa5 protein, rat; D000072040:Apolipoprotein A-V; D001053:Apolipoproteins; D016207:Cytokines; D007328:Insulin; D034741:RNA, Small Interfering; D011994:Recombinant Proteins; D000078792:Midkine