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The fission yeast transforming acidic coiled coil-related protein Mia1p/Alp7p is required for formation and maintenance of persistent microtubule-organizing centers at the nuclear envelope.

ABSTRACT: Microtubule-organizing centers (MTOCs) concentrate microtubule nucleation, attachment and bundling factors and thus restrict formation of microtubule arrays in spatial and temporal manner. How MTOCs occur remains an exciting question in cell biology. Here, we show that the transforming acidic coiled coil-related protein Mia1p/Alp7p functions in emergence of large MTOCs in interphase fission yeast cells. We found that Mia1p was a microtubule-binding protein that preferentially localized to the minus ends of microtubules and was associated with the sites of microtubule attachment to the nuclear envelope. Cells lacking Mia1p exhibited less microtubule bundles. Microtubules could be nucleated and bundled but were frequently released from the nucleation sites in mia1delta cells. Mia1p was required for stability of microtubule bundles and persistent use of nucleation sites both in interphase and postanaphase array dynamics. The gamma-tubulin-rich material was not organized in large perinuclear or microtubule-associated structures in mia1delta cells. Interestingly, absence of microtubules in dividing wild-type cells prevented appearance of large gamma-tubulin-rich MTOC structures in daughters. When microtubule polymerization was allowed, MTOCs were efficiently assembled de novo. We propose a model where MTOC emergence is a self-organizing process requiring the continuous association of microtubules with nucleation sites.

SUBMITTER: Zheng L

PROVIDER: S-EPMC1446099 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundEndocervical adenocarcinoma (ECA) is further classified as human papillomavirus (HPV)-associated (HPVA) or non-HPVA (NHPVA), per the International Endocervical Adenocarcinoma Criteria and Classification (IECC). HPVA is a glandular tumor with stromal invasion and/or exophytic expansile-type invasion, associated with the typical molecular characteristics of high-risk HPV (HR-HPV) infection. Transforming acidic coiled-coil protein-3 (TACC3),an oncogene that is frequently abnormally expressed,represents a vital biomarker for multiple human malignancies. This study aimed to examine the role of TACC3 in the diagnosis and prognosis of ECA.MethodsWe analyzed 264 patients with ECA who underwent surgical resection, classifying their tumors into HPVA and NHPVA subtypes. The expression levels of TACC3, P16, MLH1, PMS2, MSH2, MSH6 and Ki-67 in tumors were evaluated by tissue microarray using immunohistochemistry (IHC). HPV subtypes were identified in formalin-fixed paraffin-embedded (FFPE) ECA tissues by the polymerase chain reaction (PCR).ResultsECA samples showed increased TACC3 expression relative to adjacent non-carcinoma samples. TACC3 expression was higher in HPVA than in NHPA. In the HPVA subtype, high TACC3 expression was significantly correlated with P16-positive, Ki-67-high expression. Furthermore, TACC3 levels were significantly related to tumor histological type (P = 0.006), nerve invasion (P = 0.003), differentiation (P = 0.004), surgical margin (P = 0.012), parametrium invasion (P = 0.040), P16 expression (P < 0.001), and Ki-67 (P = 0.004). Additionally, Kaplan-Meier analysis showed that TACC3 upregulation was associated with poor overall survival (OS, P = 0.001), disease-free survival (DFS, P < 0.001), and recurrence survival (P < 0.001). Multivariate analysis indicated that elevated TACC3 expression served as a marker to independently predict ECA prognosis. ROC curve analyses indicated that TACC3, P16, and HPV subtypes showed similar utility for distinguishing HPVA from NHPVA, with areas under the ROC curves of 0.640, 0.649, and 0.675, respectively. The combination of TACC3 and HPV subtypes improved the diagnostic performance of ECA compared with TACC3, P16, and HPV subtypes alone.ConclusionsTaken together, our findings identify that TACC3 is a promising complementary biomarker for diagnosis and prognosis for patients with ECA.

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The fission yeast transforming acidic coiled coil-related protein Mia1p/Alp7p is required for formation and maintenance of persistent microtubule-organizing centers at the nuclear envelope.

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