CREB co-localizes with intracytoplasmic CTF aggregates and quantity of CREB is decreased in cultured cell model.

(A) In non-transfected PC12 cells, CREB and p-CREB-immunofluorescence labeling is strong in the nucleus, while the cytoplasm shows only weak and diffuse immunofluorescence. (B) In PC12 cells over-expressing rCTF-Q28-NES, the cytoplasmic CTF aggregates co-localize with CREB (upper row) and p-CREB (lower row), showing focally strong immunofluorescence in their cell bodies (arrows). (C&D) In contrast to the Dox(+) stable PC12 cells (upper row in C&D), co-localizations of CREB (lower row in C) or p-CREB (lower row in D) with cytoplasmic aggregates are also observed in Dox(−) stable PC12 cells expressing rCTF-Q28-NES (arrows). (E) The quantities of CREB and p-CREB in the nucleus were both decreased when the rCTF was expressed in the cytoplasm, but not so when the rCTF was targeted in the nucleus. (For A-D: scale bars: 10 µm).