Identification of sumoylation sites in CCDC6, the first identified RET partner gene in papillary thyroid carcinoma, uncovers a mode of regulating CCDC6 function on CREB1 transcriptional activity

• Published in: PloS one 2012-11, Vol.7 (11), p.e49298-e49298
• Main Authors: Luise, Chiara, Merolla, Francesco, Leone, Vincenza, Paladino, Simona, Sarnataro, Daniela, Fusco, Alfredo, Celetti, Angela
• Format: Article
• Language: English
• Subjects: Animals; Apoptosis; Biology; Cancer genetics; Carcinoma - genetics; Carcinoma, Papillary; Cell Line, Tumor; Cell Proliferation; Cyclic adenosine monophosphate; Cyclic AMP; Cyclic AMP Response Element-Binding Protein - genetics; Cyclic AMP Response Element-Binding Protein - metabolism; Cytoskeletal Proteins - analysis; Cytoskeletal Proteins - chemistry; Cytoskeletal Proteins - metabolism; Cytosol; Forskolin; Gene expression; Gene Expression Regulation, Neoplastic; Genetic aspects; Genomes; Genomics; Genotoxicity; HEK293 Cells; HeLa Cells; Humans; Kinases; Lysine - chemistry; Lysine - metabolism; Medicine; Papillary thyroid carcinoma; Phosphorylation; Post-translation; Protection and preservation; Protein Transport; Proteins; Proto-Oncogene Proteins c-ret - genetics; Proto-Oncogene Proteins c-ret - metabolism; Rats; RNA polymerase; Signal transduction; Signaling; Substrates; SUMO protein; Sumoylation; Thyroid; Thyroid cancer; Thyroid Cancer, Papillary; Thyroid diseases; Thyroid Neoplasms - genetics; Transcription; Transcription (Genetics); Transcription, Genetic; Translation; Translocation; Tumors; Vertebrates
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0049298

CCDC6 was originally identified in chimeric genes as caused by chromosomal translocation involving the RET protooncogene in some thyroid tumors. Recognised as a 65 kDa pro-apoptotic phosphoprotein, CCDC6 has been enrolled as an ATM substrate that contribute to protect genome integrity by modulating PP4c activity in response to genotoxic stress. Recently, CCDC6 has been identified as a repressor of CREB1-dependent transcription. Sumoylation has emerged as an important mechanism in transcriptional control. Here, we report the identification and characterization of three sites of sumoylation in CCDC6 (K74, K266 and K424) which are highly conserved in vertebrates. We demonstrate that the post-translational modifications by SUMO2 constrain most of the CCDC6 protein in the cytosol and affect its functional interaction with CREB1 with a decrease of CCDC6 repressive function on CREB1 transcriptional activity. Indeed, the impairment of functional outcome of sumoylated CCDC6 is obtained knocking down all three the sumoylation sites. Interestingly, in thyroid cells the SUMO2-mediated CCDC6 post-translational modifications are induced by Forskolin, a cAMP analog. Signal transduction via the cAMP pathway is known to be ubiquitous and represents a major line of communication between many organisms and their environment. We believe that CCDC6 could be an important player in the dynamics of cAMP signaling by fine regulating CREB1 transcriptional activity in normal and transformed thyroid cells.