Nerve growth factor nonresponsive pheochromocytoma cells: altered internalization results in signaling dysfunction

Abstract

Abstract. Variant rat pheochromocytoma (PC12) cells which fail to respond to nerve growth factor (NGF) (PC12nnr5) (Green, S. H., R. E. Rydel, J. L . Connoly, and L. A. Greene. 1986. J. Cell Biol. 102 :830-843) bind NGF at both high and low affinity sites . Although still undefined at the molecular level, these have been referred to as type I (high) and type II (low) receptors . They are apparently composed of two membrane-bound proteins, p75 and the protooncogene trk, both of which bind NGF, and apparently contribute singularly or in concert to the two observed affinities, and to the promotion of the NGF effects . In native PC12 cells, only the high affinity receptors are apparently capable of mediating internalization and degradation . PC12nnr5 cells also display type I bind-HE rat pheochromocytoma line PC12 (Greene and Tischler, 1976) is a widely used cultured cell system for the study of neurotrophic factor-induced differen tiation . Upon exposure to nerve growth factor (NGF),' for example, PC12 cells cease cell division, extend neurites, and produce the many proteins needed to become functioning neurons (for review see Greene and Tischler, 1982) . These reversible effects are mediated by the binding ofNGF to specific receptors on the plasma membrane which results in the production of a variety of intracellular signals that combine to produce the differentiated phenotype (Altin and Bradshaw, 1992) . An important aspect of these and other NGFresponsive cells is the existence of at least two distinct classes of NGF receptors that are distinguished by their affinity (Sutter et al., 1979;Schecter and Bothwell, 1981;Hosang and Shooter, 1985) . Binding experiments generally reveal a relatively small number of type I (high affinity, Kd ti 0.4 nM) NGF receptors and a larger number of type II (low affinity, Kd ti nM) receptors (Suffer et al., 1979;Schecter and Bothwell, 1981;Bernd and Greene, 1984). These binding constants differ primarily by the apparent of rate and the corresponding receptors are sometimes referred to as "slow" (type I) and "fast" (type II) . The two receptor forms apparently 1. Abbreviations used in this paper: bFGF, basic fibroblast growth factor ; NGF, nerve growth factor; PC12, rat clonal pheochromocytoma cells ; PC12nnr5, NGF nonresponsive variant of PC12 cells.

A signaling organelle containing the nerve growth factor-activated receptor tyrosine kinase, TrkA

“…There is increasing evidence that the signals generated by p75 NTR promote programmed cell death (58)(59)(60)(61) rather than prevent it, as does TrkA (62). p75 NTR is internalized and retrogradely transported, but it does not appear to be down-regulated from the cell surface in response to NGF (M.G., D. Hall, A. Schroepfel, and W.M., unpublished observations) (63)(64)(65). Moreover, p75 NTR does not appear to play a significant role in the retrograde transport of NGF, but does transport other neurotrophins (66,67).…”

Trafficking of TrkA-Green Fluorescent Protein Chimerae during Nerve Growth Factor-induced Differentiation

“…PC12 nnr5 cells, devoid of endogenous TrkA, have lost this ability to differentiate in response to NGF (27,28). Introduction of ⌬0 and ⌬1 into PC12 nnr5 cells restores NGFinduced differentiation, as shown in Fig.…”

“…5A). PC12 nnr5 cells, a variant cell line devoid of TrkA receptor, do not respond to NGF (27,28). Phosphorylation of TrkA-GFP chimerae was tested in PC12 nnr5 cells stably expressing TrkA-GFP constructs.…”

Insulin-induced egr-1 Expression in Chinese Hamster Ovary Cells Is Insulin Receptor and Insulin Receptor Substrate-1 Phosphorylation-independent

“…It has been reported that various hormones and growth factors, e.g. EGF (33), aFGF (34), bFGF (35), interleukin-1 (36), prolactin (37), nerve growth factor (38), IGF-1 (39), or growth hormone (40) internalize and translocate to the nucleus (reviewed in Refs. [41][42][43].…”