The v-Ki-Ras Oncogene Alters cAMP Nuclear Signaling by Regulating the Location and the Expression of cAMP-dependent Protein Kinase IIβ

doi:10.1074/jbc.271.41.25350

The v-Ki-Ras Oncogene Alters cAMP Nuclear Signaling by Regulating the Location and the Expression of cAMP-dependent Protein Kinase IIβ*

From the ^‡ Dipartimento Biologia e Patologia Molecolare e Cellulare, Centro di Endocrinologia ed Oncologia Sperimentale del Consiglio Nazionale delle Ricerche, Facoltà di Medicina, Università Federico II, Napoli, Italy, the
^¶ Dipartimento Medicina Sperimentale e Clinica, Facoltà di Medicina di Catanzaro, Università di Reggio Calabria, 88100 Catanzaro, Italy, the
^§ Institute of Cancer Research, Columbia University, New York, New York 10032, and the
^∥ Department of Molecular Pharmacology, Albert Einstein College of Medicine, Bronx, New York, New York 10461

^″ To whom correspondence should be addressed:
Dipartimento di Biologia e Patologia Molecolare e Cellulare, Facoltà di Medicina, II Policlinico via S. Pansini 5 80131, Napoli, Italy
. Tel.: 39-81-7463251; Fax: 39-81-7463252; E-mail: Avvedim{at}ds.unina.it

Abstract

The v-Ki-Ras oncoprotein dedifferentiates thyroid cells and inhibits nuclear accumulation of the catalytic subunit of cAMP-dependent protein kinase. After activation of v-Ras or protein kinase C, the regulatory subunit of type II protein kinase A, RIIβ, translocates from the membranes to the cytosol. RIIβ mRNA and protein were eventually depleted. These effects were mimicked by expressing AKAP45, a truncated version of the RII anchor protein, AKAP75. Because AKAP45 lacks membrane targeting domains, it induces the translocation of PKAII to the cytoplasm. Expression of AKAP45 markedly decreased thyroglobulin mRNA levels and inhibited accumulation of C-PKA in the nucleus. Our results suggest that: 1) The localization of PKAII influences cAMP signaling to the nucleus; 2) Ras alters the localization and the expression of PKAII; 3) Translocation of PKAII to the cytoplasm reduces nuclear C-PKA accumulation, resulting in decreased expression of cAMP-dependent genes, including RIIβ, TSH receptor, and thyroglobulin. The loss of RIIβ permanently down-regulates thyroid-specific gene expression.

Footnotes

↵* This work was partly supported by grants from the Associazione Italiana Ricerca Cancro, Progetti Finalizzati CNR “Ingegneria Genetica,” “Applicazioni Cliniche Ricerca Oncologica,” the Lucille P. Markey Charitable Trust, National Institutes of Health Grant 2 PO1 CA23767, and Grant DK41146. The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

PKA

cyclic AMP-dependent protein kinase

C-PKA

catalytic subunit of PKA

R

regulatory

PKC

protein kinase C

RSV

Rous sarcoma virus

NEO

neomycin

PCR

polymerase chain reaction

PAGE

polyacrylamide gel electrophoresis

PBS

phosphate-buffered saline

PKI

PKA inhibitor peptide

PMA

phorbol 12-myristate 13-acetate

MTOC

microtubule organizing center.
↵² P. Giuliano, unpublished observations.
↵³ A. Feliciello, unpublished data.
- Received June 7, 1996.
- Revision received July 31, 1996.