APC functions at the centrosome to stimulate microtubule growth

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• 作者：Christina Lui ; Cahora Ashton ; Manisha Sharma¹ ; Mariana G. Brocardo ; Beric R. Henderson ; ^{beric.henderson@sydney.edu.au" class="auth_mail" title="E-mail the corresponding author}
• 关键词：APC ; adenomatous polyposis coli ; CRC ; colorectal cancer ; γ-tuRC ; γ-tubulin ring complex ; MT ; microtubule ; MTOC ; microtubule organizing center ; PLA ; proximity ligation assay
• 刊名：International Journal of Biochemistry and Cell Biology
• 出版年：2016
• 出版时间：January 2016
• 年：2016
• 卷：70
• 期：Complete
• 页码：39-47
• 全文大小：3046 K

文摘

The adenomatous polyposis coli (APC) tumor suppressor is multi-functional. APC is known to localize at the centrosome, and in mitotic cells contributes to formation of the mitotic spindle. To test whether APC contributes to nascent microtubule (MT) growth at interphase centrosomes, we employed MT regrowth assays in U2OS cells to measure MT assembly before and after nocodazole treatment and release. We showed that siRNA knockdown of full-length APC delayed both initial MT aster formation and MT elongation/regrowth. In contrast, APC-mutant SW480 cancer cells displayed a defect in MT regrowth that was unaffected by APC knockdown, but which was rescued by reconstitution of full-length APC. Our findings identify APC as a positive regulator of centrosome MT initial assembly and suggest that this process is disrupted by cancer mutations. We confirmed that full-length APC associates with the MT-nucleation factor γ-tubulin, and found that the APC cancer-truncated form (1–1309) also bound to γ-tubulin through APC amino acids 1–453. While binding to γ-tubulin may help target APC to the site of MT nucleation complexes, additional C-terminal sequences of APC are required to stimulate and stabilize MT growth.