Intracellular distribution of Tankyrases as detected by multicolor immunofluorescence techniques

Poly(ADP-ribose) polymerases are a family of enzymes that catalyze the conversion of NAD+ into ADP-ribose. Among them, Tankyrases have been found to bind to centrosome, mitotic spindle and microsome proteins, in the cytoplasm, and to telomeres in the nucleus, where they play a relevant role in telomere metabolism. However, their precise intracellular localization during interphase has not been so far fully elucidated. We investigated this aspect in situ by double immunofluorescence experiments using antibodies recognizing Tankyrases 1–2 or other proteins residing in specific organelles (Golgi apparatus, mitochondria, lysosomes, endoplasmic reticulum). We used HeLa cells as a model system in vitro, before and after treatment with either actinomycin D or etoposide, to also investigate the possible relocation of Tankyrases during apoptosis. We observed that Tankyrases are distributed both in the nucleus and in the cytoplasm; in this latter compartment, they were found to colocate with the Golgi apparatus but never with the mitochondria; a pool of Tankyrases also colocates with the endoplasmic reticulum and lysosomes. Interestingly, in cells with clear signs of apoptosis, Tankyrases were detectable in the cytoplasmic blebs: this suggests that they are not massively cleaved during apoptosis and persist in the largely heterogeneous apoptotic remnants which are known to contain components of cytoplasmic and nuclear origin

Analysis of ERK3 intracellular localization: dynamic distribution during mitosis and apoptosis

Extracellular signal-regulated kinases (ERK) 1, 2 and 3 are involved in cell proliferation and differentiation, and apoptosis; although ERK1/2 have been widely studied, limited knowledge on ERK3 is available. The present work aimed at investigating ERK3 distribution during cell cycle and apoptosis in human tumor HeLa cells. The analysis performed by double immunofluorescence and immunoelectron microscopy experiments revealed that during interphase ERK3 is mainly resident in the nucleoplasm in association with ribonuclear proteins involved in early pre-mRNA splicing, it undergoes cell cycle-dependent redistribution and, during apoptosis, it remains in the nucleus in the form of massive nuclear aggregates, then moves to the cytoplasm and is finally extruded

Analysis of ERK3 intracellular localization: dynamic distribution during mitosis and apoptosis

Extracellular signal-regulated kinases (ERK) 1, 2 and 3 are involved in cell proliferation and differentiation, and apoptosis; although ERK1/2 have been widely studied, limited knowledge on ERK3 is available. The present work aimed at investigating ERK3 distribution during cell cycle and apoptosis in human tumor HeLa cells. The analysis performed by double immunofluorescence and immunoelectron microscopy experiments revealed that during interphase ERK3 is mainly resident in the nucleoplasm in association with ribonuclear proteins involved in early pre-mRNA splicing, it undergoes cell cycle-dependent redistribution and, during apoptosis, it remains in the nucleus in the form of massive nuclear aggregates, then moves to the cytoplasm and is finally extruded.</p