Metabolic cooperation between human fibroblasts with normal and with mutant superactive phosphoribosylpyrophosphate synthetase

Phosphoribosylpyrophosphate synthetase superactivity: A study of five patients with catalytic defects in the enzyme

“…This suggested that these women were heterozygous carriers of PRPP synthetase superactivity, even though enzyme activities in hemolysates from these women were normal. These findings are similar to those encountered in previous studies of female carriers of PRPP synthetase superactivity (2,5,8,(12)(13)(14)16,17) which have indicated that fibroblasts, but not erythrocytes, are reliable cells for the identification of the heterozygous carrier state.…”

“…Rates of PRPP and purine synthesis in fibroblasts from the female family members, RD and CE, were also increased ( Table 4), but to degrees that, in most studies, were intermediate between those of normal fibroblasts and fibroblasts from their affected sons. Attenuation of metabolic aberrations in the fibroblasts of affected females (in comparison with the cells of affected male family members) is typical of PRPP synthetase superactivity (5,8,12,14,17). This provides additional evidence that RD and CE are heterozygous carriers for X chromosome-linked enzyme superactivity.…”

“…Superactivity of phosphoribosylpyrophosphate (PRPP) synthetase, the enzyme which catalyzes the synthesis of the purine regulatory substrate, PRPP, from adenosine triphosphate (ATP) and ribose-5-P (I), has been associated with gout in nearly one dozen families (2-1 1). A causal relationship between excesses of enzyme activity, inherited as an X chromosome-linked trait (12)(13)(14), and increased rates of purine nucleotide and uric acid production has been established from detailed studies of affected members of some of these families (4)(5)(6)8,(14)(15)(16)(17). Erythrocytes and fibroblasts from these individuals show increased concentrations and rates of generation of PRPP (4-6, 8,15-17), and increased rates of purine nucleotide synthesis de novo are demonstrable both in vivo (8,16,(18)(19)(20) and in cultured fibroblasts from these patients (3)(4)(5)8,16,17).…”

Increased <i>de novo </i>Purine Synthesis in Cultured Skin Fibroblasts from Heterozygotes for the Lesch-Nyhan Syndrome

“…HGPRT-deficient cells in the mixed cul tures and thus increase the sensitivity of the test. The exposure to the selective condi tions was done at low cell densities in order to avoid metabolic cooperation between the normal and mutant cells [Zoref et al, 1976], The exposure to azaguanine resulted in death of the normal cells, whether in pure cultures or in mixed mutantmormal cul tures. No survivors were found in exposed pure normal cultures, while all cultures from the mother and from the two sisters of the patient, as well as the mixed mutantmormal cultures, whether originally with intermedi ate or high rates of purine synthesis, exhibit ed following exposure to selection augmen tation in the rate of purine synthesis.…”

Evidence for X-Linkage of Phosphoribosylpyrophosphate Synthetase in Man

“…Special care was taken to ensure that at the onset of selection all cultures contained less than 250 cells/cm2 growth surface. This was re quired since at higher cell density a contact-dependent metabolic cooperation between mutant and normal cells prevents selection [Zoref et al, 1976], Following selection, the cell cultures were allowed to grow in fresh regular growth media until confluency, and then trypsinized and propagated for one more generation. As controls, samples of each culture were grown in parallel in the normal medium.…”