Dynamic localization of -tubulin acetyltransferase ATAT1 through the cell cycle in human fibroblastic KD cells
MEDICAL MOLECULAR MORPHOLOGY
Authors: Nekooki-Machida, Yoko; Nakakura, Takashi; Nishijima, Yoshimi; Tanaka, Hideyuki; Arisawa, Kenjiro; Kiuchi, Yoshiko; Miyashita, Toshio; Hagiwara, Haruo
Abstract
Acetylation of -tubulin is a well-studied posttranscriptional modification, which is mostly catalyzed by -tubulin N-acetyltransferase (ATAT1). ATAT1 possibly affects various cellular functions related with microtubules, such as intracellular transport, cell motility, cilia formation, and neuronal signaling. Here, we analyzed the subcellular localization of immunolabeled ATAT1 in human fibroblast KD cells through the cell cycle using confocal laser scanning microscopy. ATAT1 dramatically changed its localization through the cell cycle, depending on the mitotic phase. In interphase, immunolabeled ATAT1 was observed in centrioles, nuclei, and basal bodies if the cells projected primary cilia. ATAT1 was intensely detected as clusters in the nuclei in the G1-G2 phase. In telophase, ATAT1 colocalized with chromatids and spindle poles, and ultimately migrated to the daughter nucleus, newly synthesized centrioles, and midbody. The nucleolus is a core region of ribosomal RNA transcription, and the midbody is associated with severing and depolymerizing of microtubules in the stembody. The specific distributions of ATAT1 through the cell cycle suggest multiple functions of ATAT1, which could include acetylation of microtubules, RNA transcription activity, severing microtubules, and completion of cytokinesis.
Bardet-Biedl Syndrome proteins regulate cilia disassembly during tissue maturation
CELLULAR AND MOLECULAR LIFE SCIENCES
Authors: Patnaik, Sarita Rani; Kretschmer, Viola; Bruecker, Lena; Schneider, Sandra; Volz, Ann-Kathrin; Oancea-Castillo, Liliana del Rocio; May-Simera, Helen Louise
Abstract
Primary cilia are conserved organelles that mediate cellular communication crucial for organogenesis and homeostasis in numerous tissues. The retinal pigment epithelium (RPE) is a ciliated monolayer in the eye that borders the retina and is vital for visual function. Maturation of the RPE is absolutely critical for visual function and the role of the primary cilium in this process has been largely ignored to date. We show that primary cilia are transiently present during RPE development and that as the RPE matures, primary cilia retract, and gene expression of ciliary disassembly components decline. We observe that ciliary-associated BBS proteins protect against HDAC6-mediated ciliary disassembly via their recruitment of Inversin to the base of the primary cilium. Inhibition of ciliary disassembly components was able to rescue ciliary length defects in BBS deficient cells. This consequently affects ciliary regulation of Wnt signaling. Our results shed light onto the mechanisms by which cilia-mediated signaling facilitates tissue maturation.