Meningiomas are common
central nervous system tumors; however, the mechanisms underlying their pathogenesis are largely unknown. Collaborative studies from our laboratory demonstrated a direct association of 14-3-3 with the
meningioma tumor suppressor Protein 4.1B, which was not observed with other members of the
Protein 4.1 family, including the NF2
meningioma tumor suppressor,
merlin/
schwannomin. Given the role of 14-3-3 in the regulation of cell proliferation and apoptosis, we sought to determine the functional significance of 14-3-3 binding to
Protein 4.1B growth suppression. Based on comparative binding studies performed with additional members of the
Protein 4.1 family, we generated specific missense mutations within the minimal growth suppressor fragment of
Protein 4.1B (DAL-1, differentially expressed in
adenocarcinoma of the lung). Complementary in vitro GST affinity chromatography and in vivo interaction experiments demonstrated that the F359Y mutation abrogated binding to 14-3-3, but did not impair DAL-1 binding to other known
Protein 4.1B interacting
proteins. Similar to wild-type DAL-1, the expression of the F359Y DAL-1 14-3-3-binding mutant resulted in reduced
Protein 4.1B-deficient IOMM-Lee and CH157-MN
meningioma cell line colony formation. Moreover, similar to wild-type DAL-1, the stable expression of the DAL-1 F359Y mutant significantly reduced cell proliferation in independently isolated IOMM-Lee clones, as assessed by
thymidine incorporation. Collectively, these results suggest that binding to 14-3-3 is not essential for the growth suppressor function of
Protein 4.1B in
meningiomas.