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High-Speed Atomic Force Microscopy Reveals Loss of Nuclear Pore Resilience as a Dying Code in Colorectal Cancer Cells

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posted on 2017-05-22, 00:00 authored by Mahmoud Shaaban Mohamed, Akiko Kobayashi, Azuma Taoka, Takahiro Watanabe-Nakayama, Yosuke Kikuchi, Masaharu Hazawa, Toshinari Minamoto, Yoshihiro Fukumori, Noriyuki Kodera, Takayuki Uchihashi, Toshio Ando, Richard W. Wong
Nuclear pore complexes (NPCs) are the sole turnstile implanted in the nuclear envelope (NE), acting as a central nanoregulator of transport between the cytosol and the nucleus. NPCs consist of ∼30 proteins, termed nucleoporins. About one-third of nucleoporins harbor natively unstructured, intrinsically disordered phenylalanine-glycine strings (FG-Nups), which engage in transport selectivity. Because the barriers insert deeply in the NPC, they are nearly inaccessible. Several in vitro barrier models have been proposed; however, the dynamic FG-Nups protein molecules themselves are imperceptible in vivo. We show here that high-speed atomic force microscopy (HS-AFM) can be used to directly visualize nanotopographical changes of the nuclear pore inner channel in colorectal cancer (CRC) cells. Furthermore, using MLN8237/alisertib, an apoptotic and autophagic inducer currently being tested in relapsed cancer clinical trials, we unveiled the functional loss of nucleoporins, particularly the deformation of the FG-Nups barrier, in dying cancer cells. We propose that the loss of this nanoscopic resilience is an irreversible dying code in cells. These findings not only illuminate the potential application of HS-AFM as an intracellular nanoendoscopy but also might aid in the design of future nuclear targeted nanodrug delivery tailored to the individual patient.