Related Experiment Videos
p42-MAP kinase is activated in EGF-stimulated interphase but not in metaphase-arrested HeLa cells
1Department of Physiology and Biophysics, Wright State University School of Medicine, Dayton, OH 45435, USA. j.gomez-cambronero@wright.edu
Abstract:
It is known that cellular signals produced in response to an inappropriate spindle formation cause the cell to be arrested at metaphase (M) in the cell cycle. We report here that the 42-kDa isoform of MAPK (ERK2) was tyrosyl-phosphorylated and activated in response to epidermal growth factor (EGF) in interphase but not in M-arrested HeLa cells. However, the basal level of activity of M-arrested cells was higher than that of interphase, although the overall tyrosyl phosphorylation content was small. Further, the EGF receptor and its associated proteins GTPase-activating protein and phospholipase C were phosphorylated in M-arrested cells to a lower extent than they were in interphase. This implies that in spite of its high level of basal activity, the scarcity of MAPK activation in mitosis in response to EGF stems from an early impairment of phosphorylation of the receptor and neighboring proteins. The biological significance of these results underlies the importance of keeping the cell sheltered from extracellular signals when it undergoes division.
Insights
Mitotic arrest prevents epidermal growth factor (EGF) signaling via mitogen-activated protein kinase (MAPK) activation in HeLa cells. This occurs due to impaired early-stage phosphorylation of the EGF receptor and associated proteins during M-phase.
Area of Science:
- Cell Biology
- Molecular Signaling
- Cell Cycle Regulation
Background:
- Cell cycle arrest at metaphase (M) is a known response to spindle formation defects.
- Mitogen-activated protein kinase (MAPK) pathways are crucial for cellular responses to external stimuli.
Purpose of the Study:
- To investigate the activation of MAPK (ERK2) in response to epidermal growth factor (EGF) in M-arrested HeLa cells.
- To understand the underlying mechanisms of signal transduction impairment during mitotic arrest.
Main Methods:
- Analysis of tyrosyl-phosphorylation and activation of MAPK (ERK2) in interphase and M-arrested HeLa cells.
- Assessment of epidermal growth factor receptor (EGFR) and associated protein phosphorylation.
Main Results:
- Epidermal growth factor (EGF) induced tyrosyl-phosphorylation and activation of MAPK (ERK2) in interphase but not in M-arrested HeLa cells.
- M-arrested cells exhibited higher basal MAPK activity but lower overall tyrosyl phosphorylation.
- Phosphorylation of the EGF receptor and associated proteins (GTPase-activating protein, phospholipase C) was reduced in M-arrested cells.
Conclusions:
- Mitotic arrest impairs early-stage phosphorylation events in the EGF signaling pathway.
- This impairment leads to reduced MAPK activation in response to EGF during M-phase.
- Cells are protected from extracellular signals during division to maintain genomic integrity.