title: Intracellular trafficking of RNASET2, a novel component of P-bodies.
abstract: BACKGROUND
  The ribonucleases (RNases) constitute a heterogeneous group of enzymes, which exert diverse and specific biological functions. Several RNases have been shown to control gene expression and cell differentiation. RNASET2, a novel member of the Rh/T2/S family of RNases, exerts micro-environmental control of malignancy in different experimental models with a general onco-suppressor activity, since it prevents cancer proliferation. Indeed, RNASET2 was found to be downregulated at the transcript level in several primary ovarian tumours or cell lines and in melanoma cell lines. Although recent works shed light on the biological role of RNASET2 in delaying tumour growth, its trafficking within the cell is still poorly understood. RNASET2 seems to play diverse biological roles including turnover of tRNA in yeast as well as rRNA degradation in zebrafish.
  
  
  RESULTS
  Here, we have studied the intracellular trafficking of RNASET2 in mammalian cells. RNASET2 co-localizes with markers for the trans-Golgi network (TGN), which is the central sorting and processing station of the secretory pathway. Moreover, using the temperature-sensitive vesicular stomatitis glycoprotein, we demonstrate that RNASET2 undergoes delivery to the plasma membrane. In contrast to other RNA-interacting proteins, RNASET2 does not accumulate in stress granules upon metabolic stress in mammalian cells. Surprisingly, RNASET2 shows co-localization with processing bodies (P-bodies), which increases upon metabolic stress. Finally, cells lacking RNASET2 show a reduced numbers of P-bodies.
  
  
  CONCLUSIONS
  In this study, we have identified two distinct cellular pools of RNASET2-containing granules. One pool undergoes membrane delivery using the TGN, and it is released to the extracellular environment. The second pool is recruited into P-bodies, suggesting a possible involvement of RNASET2 in P-body formation in mammalian cells.
authors.affiliation: Molecular and Cellular Neurobiology Laboratory, Centre for Integrative Biology, University of Trento, Via Delle Regole 101, 38123 Mattarello, Trento, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Vidalino
authors.forename: Laura
authors.initials: L
authors.lastname: Monti
authors.forename: Albrecht
authors.initials: A
authors.lastname: Haase
authors.forename: Albertomaria
authors.initials: A
authors.lastname: Moro
authors.forename: Francesco
authors.initials: F
authors.lastname: Acquati
authors.forename: Roberto
authors.initials: R
authors.lastname: Taramelli
authors.forename: Paolo
authors.initials: P
authors.lastname: Macchi
mesh_terms: D045744:Cell Line, Tumor; D006367:HeLa Cells; D006801:Humans; D021381:Protein Transport / Q000502:physiology; D012260:Ribonucleases / Q000235:genetics / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism*; D021601:trans-Golgi Network / Q000378:metabolism
chemical_list: D025521:Tumor Suppressor Proteins; D012260:Ribonucleases; C425232:RNASET2 protein, human