Functional analysis of the relationship between the neurofibromatosis 2 tumor suppressor and its binding partner, hepatocyte growth factor-regulated tyrosine kinase substrate.
Individuals with the neurofibromatosis 2 (NF2) inherited tumor predisposition syndrome are prone to the development of nervous system tumors, including schwannomas and meningiomas. The NF2 tumor suppressor protein, merlin or schwannomin, inhibits cell growth and motility as well as affects actin cytoskeleton-mediated processes. Merlin interacts with several proteins that might mediate merlin growth suppression, including hepatocyte growth factor-regulated tyrosine kinase substrate (HRS or HGS). Previously, we demonstrated that regulated overexpression of HRS in RT4 rat schwannoma cells had the same functional consequences as regulated overexpression of merlin. To determine the functional significance of this interaction, we generated a series of HRS truncation mutants and defined the regions of HRS required for merlin binding and HRS growth suppression. The HRS domain required for merlin binding was narrowed to a region (residues 470-497) containing the predicted coiled-coil domain whereas the major domain responsible for HRS growth suppression was distinct (residues 498-550). To determine whether merlin growth suppression required HRS, we demonstrated that merlin inhibited growth in HRS (+/+), but not HRS( -/-) mouse embryonic fibroblast cells. In contrast, HRS could suppress cell growth in the absence of Nf2 expression. These results suggest that merlin growth suppression requires HRS expression and that the binding of merlin to HRS may facilitate its ability to function as a tumor suppressor.
Sun
Chun-Xiao
CX
Department of Neurology, Washington University School of Medicine, St Louis, MO 63110, USA.
Haipek
Carrie
C
Scoles
Daniel R
DR
Pulst
Stefan M
SM
Giovannini
Marco
M
Komada
Masayuki
M
Gutmann
David H
DH
D016475:3T3 Cells; D017398:Alternative Splicing / Q000235:genetics; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D002460:Cell Line; D004622:Embryo, Mammalian; D056827:Endosomal Sorting Complexes Required for Transport; D016515:Genes, Neurofibromatosis 2 / Q000502:physiology; D006801:Humans; D051379:Mice; D008817:Mice, Mutant Strains; D009442:Neurilemmoma / Q000235:genetics / Q000473:pathology; D016518:Neurofibromatosis 2 / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology*; D025581:Neurofibromin 2 / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D010446:Peptide Fragments / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D010750:Phosphoproteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D017434:Protein Structure, Tertiary / Q000235:genetics; D051381:Rats; D014407:Tumor Cells, Cultured
D056827:Endosomal Sorting Complexes Required for Transport; D025581:Neurofibromin 2; D010446:Peptide Fragments; D010750:Phosphoproteins; C096164:hepatocyte growth factor-regulated tyrosine kinase substrate