1: Oncogene. 1999 Nov 18;18(48):6810-7. 

Nmi protein interacts with regions that differ between MycN and Myc and is
localized in the cytoplasm of neuroblastoma cells in contrast to nuclear MycN.

Bannasch D, Weis I, Schwab M.

Division of Cytogenetics-H0400, Deutsches Krebsforschungszentrum, Heidelberg,
Germany.

Myc family proteins play an important role in cellular processes such as
proliferation, differentiation, apoptosis and transformation. A number of
interaction partners of Myc have been identified, such as Max, p107, TBP, YY1,
Miz-1, AP-2 and Nmi. Both Max and Nmi also bind to MycN. In contrast to the well
defined binding of Max to Myc family proteins the interaction of Nmi with Myc or
MycN is only poorly characterized. By employing the yeast two-hybrid system we
have mapped the regions of MycN and Myc responsible for binding to Nmi. For MycN
exclusively a central region mediates binding to Nmi. In contrast, for Myc a
C-terminal portion of the protein, and possibly also a central part, is involved
in Nmi interaction. Nmi does not interact with Max and has no transactivation
capabilities in yeast, suggesting that Nmi alone is not a transcriptional
activator in mammalian cells. Immunofluorescence demonstrates that both in 293
embryonic kidney cells and in Kelly neuroblastoma cells all detectable
ectopically expressed Nmi is localized in the cytoplasm, in part in a punctate,
granular pattern. MycN, which is highly expressed in Kelly cells consequent to
amplification, appears to be localized exclusively in the nuclei. This directly
demonstrates that in the same cell at least the major proportion of MycN and Nmi
is localized in different cellular compartments. This result is confirmed by the
finding that endogenous Nmi, which is expressed in Kelly cells only after
stimulation with interferon gamma, is detected exclusively in the cytoplasm of
these cells. Therefore only a very small amount of MycN and Nmi is likely to be
involved in MycN/Nmi interaction in vivo.

PMID: 10597290 [PubMed - indexed for MEDLINE]


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