HSP70 is required for the proper assembly of pericentriolar material and function of mitotic centrosomes
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(2019) 14:4 Fang et al. Cell Div https://doi.org/10.1186/s13008-019-0047-7
Open Access
RESEARCH
HSP70 is required for the proper assembly of pericentriolar material and function of mitotic centrosomes Chieh‑Ting Fang1,2, Hsiao‑Hui Kuo2, Shao‑Chun Hsu2 and Ling‑Huei Yih2*
Abstract Background: At the onset of mitosis, the centrosome expands and matures, acquiring enhanced activities for microtubule nucleation and assembly of a functional bipolar mitotic spindle. However, the mechanisms that regulate centrosome expansion and maturation are largely unknown. Previously, we demonstrated in an immortalized human cell line CGL2 and cancer cell line HeLa that the inducible form of heat shock protein 70 (HSP70) accumulates at the mitotic centrosome and is required for centrosome maturation and bipolar spindle assembly. Results: In this study, we further show that HSP70 accumulated at the spindle pole in a PLK1-dependent manner. HSP70 colocalized with pericentrin (PCNT), CEP215 and γ-tubulin at the spindle pole and was required for the 3D assembly of these three proteins, which supports mitotic centrosome function. Loss of HSP70 disrupted mitotic cen‑ trosome structure, reduced pericentriolar material recruitment and induced fragmentation of spindle poles. In addi‑ tion, HSP70 was necessary for the interaction between PCNT and CEP215 and also facilitated PLK1 accumulation and function at the spindle pole. Furthermore, we found that HSP70 chaperone activity is required for PCNT accumulation at the mitotic centrosome and assembly of mitotic spindles. Conclusion: Our current results demonstrate that HSP70 is required for the accurate assembly of the pericentriolar material and proper functioning of mitotic centrosomes. Keywords: HSP70, Mitotic centrosome, Pericentriolar material, Spindle pole Background The centrosome is a structurally complex and functionally diverse organelle that regulates various cellular processes. It consists of a pair of barrel-shaped structures called centrioles and a surrounding protein complex, which is referred to as the pericentriolar material (PCM). The PCM contains hundreds of proteins, including signaling molecules, cell cycle regulators and crucial microtubule (MT)-nucleating factors. The combined function of these proteins makes the centrosome the major MTorganizing center (MTOC), which coordinates all MTrelated functions, including cell shape, cell polarity, mobility, intracellular trafficking and cell division [1]. *Correspondence: [email protected] 2 Institute of Cellular and Organismic Biology, Academia Sinica, Taipei 115, Taiwan Full list of author information is available at the end of the article
The centrosome is duplicated during S phase along with DNA replication, yielding two centrosomes that nucleate extensive MT arrays and form the two poles of the mitotic spindle [2]. Importantly, from late S phase to mitotic onset, the two fully duplicated centrosomes exhibit enhanced recruitment of PCM components that are essential for MT nucleation, a process termed centrosome m
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