D-glucose metabolism in dimethyl suberimidate-treated tumoral pancreatic islet cells.
After protein cross-linking by dimethyl suberimidate, tumoral insulin-producing cells of the RINm5F line were either exposed to digitonin for measurement of hexokinase activity in the resulting cell pellet and supernatant, or incubated in the presence of D-[5-3H]glucose, D-[U-14C]glucose or L-[U-14C]glutamine to assess the metabolism of these nutrients. After digitonin treatment, the activity of hexokinase recovered in the cell pellet was about 40% higher in cross-linked than control RINm5F cells. Although failing to affect the metabolism of L-[U-14C]glutamine, and severely decreasing the oxidation of D-[U-14C]glucose, the cross-linking of proteins accentuated the increase in D-[5-3H]glucose utilization and D-[U-14C]glucose conversion to acidic metabolites resulting from a rise in hexose concentration from 2.8 to 16.7 mM. The latter change represents a mirror image of that previously found in cross-linked pancreatic islets. Taking into account the vastly different participation of glucokinase to hexose phosphorylation in RINm5F cells and normal islet cells, the present findings further support, therefore, the regulatory role of protein-to-protein interaction in the control of glucokinase catalytic activity in these fuel-sensing cells.
Vanhoutte
C
C
Laboratory of Experimental Medicine, Brussels Free University, Belgium.
Malaisse
W J
WJ
D000818:Animals; D003432:Cross-Linking Reagents; D004072:Digitonin / Q000494:pharmacology; D004120:Dimethyl Suberimidate / Q000378:metabolism* / Q000494:pharmacology; D005636:Fructosephosphates / Q000378:metabolism; D005947:Glucose / Q000737:chemistry / Q000378:metabolism*; D019298:Glucose-6-Phosphate / Q000378:metabolism; D005973:Glutamine / Q000187:drug effects / Q000378:metabolism; D006593:Hexokinase / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000378:metabolism; D007340:Insulinoma / Q000737:chemistry / Q000378:metabolism*; D051381:Rats; D014407:Tumor Cells, Cultured
D003432:Cross-Linking Reagents; D005636:Fructosephosphates; D005973:Glutamine; D004120:Dimethyl Suberimidate; D019298:Glucose-6-Phosphate; C027618:fructose-6-phosphate; D006593:Hexokinase; D005947:Glucose; D004072:Digitonin