Localización subcelular de p8 dependiente de la densidad celular

VALACCO, MP C.VARONE, E. CANEPA, J. IOVANNA, AND S.MORENO

Cordoba, Argentina

Congreso; XXXVIII Reunión Anual SAIB; 2002

Sociedad Argentina de Investigacion Bioquimica

p8 was first identified by its induction during the acute phase of pancreatitis. Its mRNA is expressed in cell lines in response to stress and mitogenic factors. Preliminary results suggest that p8 could be acting as a cellular growth factor. The objective of this work is to study the cellular localization of p8. Sequence homology analysis in databases indicates that apart from the known homology between human, rat, mice, Xenopus laevis and Drosophila melanogaster p8, there is homology with pig, cow, fish and arthropods. Further analysis of hp8, showed that it contains a putative bipartite NLS, and remarkably, this NLS is conserved in all these species. With immunocytochemistry we studied the intracellular localization of p8 and observed that it is affected by the density of the cell monolayer. It is cytoplasmic in cells grown in dense culture, but nuclear in cells grown in sparse culture. This was observed in the endogenous protein in HEK 293T cells, in proteins expressed by transient transfection in HeLa and NIH3T3 cells, and in stably transfected HeLa cells. We can conclude that this localization pattern does not depend on the level of expression of the protein, nor of the promoter that directs the expression, nor of the cell type. Mutants of the lysines found in the putative NLS region were constructed. Preliminary results indicate that the first two lysines dont seem to be involved in p8 localization. Further studies to find out p8 migration mechanism are to be performed.