p53 associates with trk tyrosine kinase

Abstract

The p53 tumor suppressor gene encodes a phosphoprotein which when overexpressed can induce growth arrest at the G1 and G2/M phases of the cell cycle, promote di erentiation and apoptosis. This paper demonstrates that p53 can associate with trk tyrosine kinase. Expression of a murine temperature-sensitive (ts) p53 mutant in PC12 cells overexpressing trk (a model system to analyse cellular di erentiation and signal transduction induced by NGF) induces morphological changes in the absence of NGF stimulation at 328C but not at 378C. In cells di erentiated by p53, trk, but not EGFr, was hyperphosphorylated on tyrosine. Furthermore trk was not phosphorylated when expressed in Saos-2 cells (human osteosarcoma cells that lack expression of both endogenous trk and p53) at either temperature. However, transfection of ts p53 into these cells induces trk phosphorylation at 328C in the absence of NGF stimulation. Association of trk and p53 can be detected in NIH3T3 and PC12 cells co-expressing trk and the ts p53 mutant, in NIH3T3 and PC12 cells transfected with trk alone, and in untransfected PC12 cells, showing that overexpressed and/or endogenous trk associates with endogenous, low levels of p53. These data suggest a novel function for p53 which involves the stimulation of signal transduction pathways (mediating morphological properties of cells), possibly through association with and hyperphosphorylation of trk.

c-abl is involved in the association of p53 and trk A

“…Cell extracts of NGF stimulated NIHtrk+tsp53-2 grown at 328C, NIH3T3 and p53 negative cells (p53 7/7 ) were immunoprecipitated with either anti-trk A B-3 or PAb 248 antibodies. Immunoblotting analysis with anti-trk 203 antibodies showed that PAb 248 was able to coprecipitate trk A associated with p53 and when comparing total to bound trk A, 25 ± 30% of the trk A from cell extracts associated with p53 in agreement with previous results (Montano, 1997). PAb 248 did not appear to non-speci®cally recognize any other protein(s) (Figure 1c).…”

“…The same result was obtained after prolonged exposures. Also, when cell extracts of p53 7/7 cells transfected with trk A (p53 7/7 trk A) were immunoprecipitated with PAb 248; immunoblotting analysis with anti-trk A 203 antibodies showed that PAb 248 did not immunoprecipitate trk A in agreement with previous data (Montano, 1997). Therefore, these results show that PAb 248 and anti-abl ab-3 only recognize p53 and cabl respectively.…”

“…p53 is a transcriptional activator which exhibits cell cycle-dependent localization, it moves from the cytoplasm to the nucleus at S phase and returns to the cytoplasm as cell division progresses to G1 (Shaulsky et al, 1990;Zerrahn et al, 1992). Overexpression of p53 can induce cell cycle arrest at the G1 and G2/M phases (Aloni-Grinstein et al, 1995;Michalovitz et al, 1990), and promote apoptosis or di erentiation (Shaulsky et al, 1991;Montano, 1997).…”

“…Recent data shows that there is association between trk A and p53 (Montano, 1997). When baculovirus expressed kinase-active trk A was co-immunoprecipitated with in vitro transcribed and translated wild type p53, at least 25 times more of the immunoprecipitated wild type p53 bound to trk A compared to the EGF receptor (EGFr).…”

“…To determine if endogenous c-abl was present in the p53 and trk A complex; cell extracts of NGF stimulated NIH3T3 cells expressing trk A (NIHtrk) and NIH3T3 cells expressing trk A and a ts p53 (val 135) mutant (NIHtrk+ts p53-2) grown at 32 or 378C respectively (Montano, 1997) were immunoprecipitated with PAb 248 (an antibody that recognizes murine p53 at amino acids 40 ± 52 (Yewdell et al, 1986)). Immunoblotting analysis with anti-abl antibodies showed that endogenous c-abl was present in the immunoprecipitates (Figure 1a,b).…”