title: Nuclear-to-cytoplasmic relocalization of the proliferating cell nuclear antigen (PCNA) during differentiation involves a chromosome region maintenance 1 (CRM1)-dependent export and is a prerequisite for PCNA antiapoptotic activity in mature neutrophils.
abstract: Neutrophils are deprived of proliferative capacity and have a tightly controlled lifespan to avoid their persistence at the site of injury. We have recently described that the proliferating cell nuclear antigen (PCNA), a nuclear factor involved in DNA replication and repair of proliferating cells, is a key regulator of neutrophil survival. In neutrophils, PCNA was localized exclusively in the cytoplasm due to its nuclear-to-cytoplasmic relocalization during granulocytic differentiation. We showed here that leptomycin B, an inhibitor of the chromosome region maintenance 1 (CRM1) exportin, inhibited PCNA relocalization during granulocytic differentiation of HL-60 and NB4 promyelocytic cell lines and of human CD34(+) primary cells. Using enhanced green fluorescent protein fusion constructs, we have demonstrated that PCNA relocalization involved a nuclear export signal (NES) located from Ile-11 to Ile-23 in the PCNA sequence. However, this NES, located at the inner face of the PCNA trimer, was not functional in wild-type PCNA, but instead, was fully active and leptomycin B-sensitive in the monomeric PCNAY114A mutant. To test whether a defect in PCNA cytoplasmic relocalization would affect its antiapoptotic activity in mature neutrophils, a chimeric PCNA fused with the SV40 nuclear localization sequence (NLS) was generated to preclude its cytoplasmic localization. As expected, neutrophil-differentiated PLB985 cells expressing ectopic SV40NLS-PCNA had an increased nuclear PCNA as compared with cells expressing wild-type PCNA. Accordingly, the nuclear PCNA mutant did not show any antiapoptotic activity as compared with wild-type PCNA. Nuclear-to-cytoplasmic relocalization that occurred during myeloid differentiation is essential for PCNA antiapoptotic activity in mature neutrophils and is dependent on the newly identified monomerization-dependent PCNA NES.
authors: INSERM U1016, 75014 Paris, France.
authors: Dikra
authors: D
authors: Bouayad
authors: Magali
authors: M
authors: Pederzoli-Ribeil
authors: Julie
authors: J
authors: Mocek
authors: Céline
authors: C
authors: Candalh
authors: Jean-Benoît
authors: JB
authors: Arlet
authors: Olivier
authors: O
authors: Hermine
authors: Nathalie
authors: N
authors: Reuter
authors: Noélie
authors: N
authors: Davezac
authors: Véronique
authors: V
authors: Witko-Sarsat
mesh_terms: D021581:Active Transport, Cell Nucleus; D017209:Apoptosis; D015153:Blotting, Western; D002454:Cell Differentiation; D002467:Cell Nucleus / Q000378:metabolism*; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism*; D005231:Fatty Acids, Unsaturated / Q000737:chemistry; D006098:Granulocytes / Q000166:cytology; D018922:HL-60 Cells; D006367:HeLa Cells; D006801:Humans; D007249:Inflammation; D028884:Karyopherins / Q000378:metabolism*; D008958:Models, Molecular; D009154:Mutation; D009503:Neutropenia / Q000378:metabolism; D009504:Neutrophils / Q000166:cytology*; D018809:Proliferating Cell Nuclear Antigen / Q000737:chemistry*; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D000097606:Exportin 1 Protein
chemical_list: D005231:Fatty Acids, Unsaturated; D028884:Karyopherins; D018809:Proliferating Cell Nuclear Antigen; D018160:Receptors, Cytoplasmic and Nuclear; D000097606:Exportin 1 Protein; C038753:leptomycin B