Analysis of the Growth and Transformation Suppressor Domains of Promyelocytic Leukemia Gene, PML

doi:10.1074/jbc.271.1.130

Analysis of the Growth and Transformation Suppressor Domains of Promyelocytic Leukemia Gene, PML(*)

From the Division of Laboratory Medicine, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030

^§ To whom correspondence should be addressed:
Div. of Laboratory Medicine, Box 72, The University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030.
Tel.: 713-792-2581; Fax: 713-794-1800.

Abstract

The promyelocytic leukemia gene (PML) involved in the t(15;17) (q22;q12) translocation in acute promyelocytic leukemia is a growth suppressor. To elucidate the functional domains of PML, several mutants lacking the nuclear localization signal (PMLnls-), the dimerization domain (PMLdim-), the proline-rich domain at the N-terminal (PMLpro-), the proline-rich RING finger motif (PMLpr-), the proline-rich RING finger B-box-1 (PMLprb-), the serine-proline-rich domain at the C-terminal (PMLsp-), and the double mutant (PMLprb-nls-) have been constructed. Immunofluorescence staining of transiently transfected NIH3T3 cells demonstrated that the RING finger motif, dimerization domain, and nuclear localization signal are all required for the formation of PML oncogenic domains (PODs). Immunofluorescence staining of transiently transfected GM637D human fibroblasts indicated that expression of PMLprb-, PMLnls-, and PMLprb-nls- led to a significant reduction or, in some cases, complete elimination of PODs. PMLdim-, PMLnls-, PMLpr-, PMLprb-, and PMLprb-nls- mutants were found to lose their ability to suppress transformation of NIH3T3 cells by activated neu, while PMLpro- and PMLsp- mutants did not. These results suggest that the ability of PML to form a POD is essential for suppression of growth and transformation. Furthermore, since PMLprb-, PMLnls-, and PMLprb-nls- mutants could block the suppression effect of wild-type PML on transformation of NIH3T3 cells by the neu oncogene, these PML mutants are potential dominant negative inhibitors of PML. Our study also suggests that the RING finger motif may interact with other nuclear proteins.

Footnotes

↵* This study was supported by Grant CA55577 from the National Institutes of Health (to K.-S. C.). The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

APL

acute promyelocytic leukemia

POD

PML oncogenic domains

ATRA

all-trans-retinoic acid

RXR

retinoic X receptor

RARα

retinoic acid receptor-α.
↵²X.-F. Le, P. Yang, and K.-S. Chang, unpublished results.
↵³X.-F. Le, P. Yang, and K.-S. Chang, unpublished observations.
- Received August 18, 1995.
- Revision received October 30, 1995.