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Glucose metabolism in fibroblasts from patients with erythrocyte hexokinase deficiency
Author(s) -
Magnani M.,
Chiarantini L.,
Stocchi V.,
Dachà M.,
Fornaini G.
Publication year - 1986
Publication title -
journal of inherited metabolic disease
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.462
H-Index - 102
eISSN - 1573-2665
pISSN - 0141-8955
DOI - 10.1007/bf01799449
Subject(s) - hexokinase , hexose , oxidative phosphorylation , enzyme , isozyme , glycolysis , medicine , biochemistry , pentose phosphate pathway , biology , red blood cell , endocrinology , metabolism , carbohydrate metabolism , cell culture , chemistry , genetics
Four different hexokinase (HK) isoenzymes are distributed in different proportions in human tissues. Fibroblasts contain HK type I as the predominant glucose phosphorylating activity, the same isoenzyme that predominates in red blood cells (RBC). We have established cell lines from two patients homozygous for RBC HK deficiency but carrying different mutations. In one case (HK‐Melzo) the residual RBC enzyme shows a marked heat instability but possesses normal kinetic and regulatory properties; in the other (HK‐Napoli), the enzyme is characterized by an increased K i for glucose‐1,6‐diphosphate. These properties are also retained by the fibroblasts' hexokinase. Glucose utilization by cultured fibroblasts from these patients was markedly reduced in the cell lines where HK deficiency was more pronounced. However, cells with only 30% HK activity retained their full ability to utilize glucose in the hexose monophosphate pathway. This was shown to be true not only under basal conditions but also in the presence of oxidative agents such as methylene blue. Significant reduction of the ATP level was also found in HK‐Melzo fibroblasts. Thus, HK deficiency is associated with reduced glucose utilization and normal hexose monophosphate shunt rates. Results previously obtained on RBC support similar conclusions.