E. Yakovchenko et al., INSULIN-LIKE GROWTH-FACTOR-I RECEPTOR EXPRESSION AND FUNCTION IN NERVE GROWTH-FACTOR - DIFFERENTIATED PC12 CELLS, Journal of neurochemistry, 67(2), 1996, pp. 540-548
Receptors for insulin-like growth factor I (IGF-I) were studied on PC1
2EY cells, a subclone of PC12. Differentiation of PC12EY cells with ne
rve growth factor (NGF) did not alter either the number of IGF-I recep
tors nor their affinity for IGF-I. IGF-I receptors remained fully func
tional during differentiation, promoting increases in thymidine incorp
oration, glucose uptake, amino acid uptake, and the phosphorylation of
the S6 protein of the ribosomes. IGF-I also increased the proportion
of differentiated cells found in S-phase. But although the addition of
IGF-I to naive cells caused an increase in cell number, there was no
comparable increase when IGF-I was added to differentiated cells. Thus
, although the receptor for IGF-I continues to be present and function
al, IGF-I fails to induce cell proliferation in differentiated PC12 ce
lls.