The polyproline-motif of S6K2: eIF5A translational dependence and importance for protein-protein interactions

Autor(es)

Meneguello, Leticia ^{[1, 2]} ; Barbosa, Natalia M. ^[3] ; Pereira, Karina D. ^{[1, 2]} ; Proenca, Andre R. G. ^[2] ; Tamborlin, Leticia ^{[1, 2]} ; Simabuco, Fernando M. ^[4] ; Iwai, Leo K. ^[5] ; Zanelli, Cleslei F. ^[3] ; Valentini, Sandro R. ^[3] ; Luchessi, Augusto D. ^{[1, 2]}

Afiliação do(s) autor(es)

^[1] Sao Paulo State Univ UNESP, Inst Biosci, Dept Biol, Rio Claro - Brazil

^[2] Univ Campinas UNICAMP, Sch Appl Sci, Lab Biotechnol, Limeira - Brazil

^[3] Sao Paulo State Univ UNESP, Sch Pharmaceut Sci, Dept Biol Sci, Araraquara - Brazil

^[4] Univ Campinas UNICAMP, Sch Appl Sci, Lab Funct Properties Foods, Limeira - Brazil

^[5] Butantan Inst, Ctr Toxins Immune Response & Cell Signaling, Special Lab Appl Toxinol, LETA CeTICS, Butanta - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Journal of Cellular Biochemistry; v. 120, n. 4, p. 6015-6025, APR 2019.
• Citações Web of Science: 1

Resumo

Ribosomal S6 kinase 1 (S6K1) and S6K2 proteins are effectors of the mammalian target of rapamycin complex 1 pathway, which control the process of protein synthesis in eukaryotes. S6K2 is associated with tumor progression and has a conserved C-terminus polyproline rich motif predicted to be important for S6K2 interactions. It is noteworthy that the translation of proteins containing sequential prolines has been proposed to be dependent of eukaryotic translation initiation factor 5A (eIF5A) translation factor. Therefore, we investigated the importance of polyproline-rich region of the S6K2 for its intrinsic phosphorylation activity, protein-protein interaction and eIF5A role in S6K2 translation. In HeLa cell line, replacing S6K2 polyproline by the homologous S6K1-sequence did not affect its kinase activity and the S6K2 endogenous content was maintained after eIF5A gene silencing, even after near complete depletion of eIF5A protein. Moreover, no changes in S6K2 transcript content was observed, ruling out the possibility of compensatory regulation by increasing the mRNA content. However, in the budding yeast model, we observed that S6K2 production was impaired when compared with S6K2 increment Pro, after reduction of eIF5A protein content. These results suggest that although the polyproline region of S6K2 is capable of generating ribosomal stalling, the depletion of eIF5A in HeLa cells seems to be insufficient to cause an expressive decrease in the content of endogenous S6K2. Finally, coimmunoprecipitation assays revealed that the replacement of the polyproline motif of S6K2 alters its interactome and impairs its interaction with RPS6, a key modulator of ribosome activity. These results evidence the importance of S6K2 polyproline motif in the context of S6Ks function. (AU)

• Processo FAPESP: 13/07467-1 - CeTICS - Centro de Toxinas, Imuno-Resposta e Sinalização Celular
• Beneficiário: Hugo Aguirre Armelin
• Linha de fomento: Auxílio à Pesquisa - Centros de Pesquisa, Inovação e Difusão - CEPIDs
• Processo FAPESP: 10/18095-0 - Estudo do fator de início de tradução de eucariotos 5A (eIF5A) em mamíferos
• Beneficiário: Augusto Ducati Luchessi
• Linha de fomento: Auxílio à Pesquisa - Apoio a Jovens Pesquisadores
• Processo FAPESP: 12/13558-7 - Caracterização molecular das proteínas S6Ks na obesidade e em suas doenças associadas
• Beneficiário: Fernando Moreira Simabuco
• Linha de fomento: Auxílio à Pesquisa - Apoio a Jovens Pesquisadores