Human MAP9 (Microtubule-associated protein 9) ELISA Kit

Background: Chromosomal instability plays an important part in cancer, but its genetic basis in liver tumorigenesis remains largely unclear. We aimed to characterize the mechanistic significance and clinical implication of mitotic regulator microtubule-associated protein 9 (MAP9) in hepatocellular carcinoma (HCC). Methods: The biological functions of MAP9 were determined by in vitro tumorigenicity assays. Systematic MAP9 knockout mouse (MAP9(Delta/Delta)) and hepatocyte-specific MAP9 knockout mouse (MAP9(Delta/Delta hep)) were generated to confirm the role of MAP9 in HCC. The clinical impact of MAP9 was assessed in primary HCC tissue samples. Findings: We found that MAP9 was frequently silenced in HCC tissue samples. The transcriptional silence of MAP9 in liver cancer cell lines and tissue samples was mediated by its promoter hypermethylation. MAP9 promoter hypermethylation or downregulation was associated with poor survival and recurrence in patients with HCC. Mechanistically, ectopic expression of MAP9 in LO2 and HepG2 cell lines impaired cell proliferation, colony formation, migration and invasion, and induced cell apoptosis and cycle arrest, whereas knockdown of MAP9 in Miha cell line showed the opposite effects. We found that MAP9(Delta/Delta) mice spontaneously developed a liver hyperplastic nodule and MAP9(Delta/Delta hep) accelerated diethylnitrosamine-induced HCC formation. The tumour suppressive effect of MAP9 in HCC was mediated by downregulating excision repair cross-complementation group 3 (ERCC3), a nucleotide excision repair gene. Restoration of ERCC3 expression possessed an oncogenic potency and abrogated the tumour suppressive effects of MAP9. Interpretation: MAP9 is a novel tumour suppressor in HCC by inhibiting ERCC3 expression, and serves as a prognostic factor in HCC patients. (c) 2020 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license. (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Background: ASAP is a newly characterized microtubule-associated protein ( MAP) essential for proper cell-cycling. We have previously shown that expression deregulation of human ASAP results in profound defects in mitotic spindle formation and mitotic progression leading to aneuploidy, cytokinesis defects and/or cell death. In the present work we analyze the structure and evolution of the ASAP gene, as well as the domain composition of the encoded protein. Mouse and Xenopus cDNAs were cloned, the tissue expression characterized and the overexpression profile analyzed. Results: Bona fide ASAP orthologs are found in vertebrates with more distantly related potential orthologs in invertebrates. This single-copy gene is conserved in mammals where it maps to syntenic chromosomal regions, but is also clearly identified in bird, fish and frog. The human gene is strongly expressed in brain and testis as a 2.6 Kb transcript encoding a similar to 110 KDa protein. The protein contains MAP, MIT-like and THY domains in the C-terminal part indicative of microtubule interaction, while the N-terminal part is more divergent. ASAP is composed of similar to 42% alpha helical structures, and two main coiled-coil regions have been identified. Different sequence features may suggest a role in DNA damage response. As with human ASAP, the mouse and Xenopus proteins localize to the microtubule network in interphase and to the mitotic spindle during mitosis. Overexpression of the mouse protein induces mitotic defects similar to those observed in human. In situ hybridization in testis localized ASAP to the germ cells, whereas in culture neurons ASAP localized to the cell body and growing neurites. Conclusion: The conservation of ASAP indicated in our results reflects an essential function in vertebrates. We have cloned the ASAP orthologs in mouse and Xenopus, two valuable models to study the function of ASAP. Tissue expression of ASAP revealed a high expression in brain and testis, two tissues rich in microtubules. ASAP associates to the mitotic spindle and cytoplasmic microtubules, and represents a key factor of mitosis with possible involvement in other cell cycle processes. It may have a role in spermatogenesis and also represents a potential new target for antitumoral drugs. Possible involvement in neuron dynamics also highlights ASAP as a candidate target in neurodegenerative diseases.