Kinesin-7 CENP-E mediates chromosome alignment and spindle assembly checkpoint in meiosis I.

In eukaryotes, meiosis is the genetic basis for sexual reproduction, which is important for chromosome stability and species evolution. The defects in meiosis usually lead to chromosome aneuploidy, reduced gamete number, and genetic diseases, but the pathogenic mechanisms are not well clarified. Kinesin-7 CENP-E is a key regulator in chromosome alignment and spindle assembly checkpoint in cell division. However, the functions and mechanisms of CENP-E in male meiosis remain largely unknown. In this study, we have revealed that the CENP-E gene was highly expressed in the rat testis. CENP-E inhibition influences chromosome alignment and spindle organization in metaphase I spermatocytes. We have found that a portion of misaligned homologous chromosomes is located at the spindle poles after CENP-E inhibition, which further activates the spindle assembly checkpoint during the metaphase-to-anaphase transition in rat spermatocytes. Furthermore, CENP-E depletion leads to abnormal spermatogenesis, reduced sperm count, and abnormal sperm head structure. Our findings have elucidated that CENP-E is essential for homologous chromosome alignment and spindle assembly checkpoint in spermatocytes, which further contribute to chromosome stability and sperm cell quality during spermatogenesis.

Loss-of-function of kinesin-5 KIF11 causes microcephaly, chorioretinopathy, and developmental disorders through chromosome instability and cell cycle arrest.

Kinesin motors play a fundamental role in development by controlling intracellular transport, spindle assembly, and microtubule organization. In humans, patients carrying mutations in KIF11 suffer from an autosomal dominant inheritable disease called microcephaly with or without chorioretinopathy, lymphoedema, or mental retardation (MCLMR). While mitotic functions of KIF11 proteins have been well documented in centrosome separation and spindle assembly, cellular mechanisms underlying KIF11 dysfunction and MCLMR remain unclear. In this study, we generate KIF11-inhibition chick and zebrafish models and find that KIF11 inhibition results in microcephaly, chorioretinopathy, and severe developmental defects in vivo. Notably, loss-of-function of KIF11 causes the formation of monopolar spindle and chromosome misalignment, which finally contribute to cell cycle arrest, chromosome instability, and cell death. Our results demonstrate that KIF11 is crucial for spindle assembly, chromosome alignment, and cell cycle progression of progenitor stem cells, indicating a potential link between polyploidy and MCLMR. Our data have revealed that KIF11 inhibition cause microcephaly, chorioretinopathy, and development disorders through the formation of monopolar spindle, polyploid, and cell cycle arrest.

Generation of Centromere-Associated Protein-E CENP-E-/- Knockout Cell Lines using the CRISPR/Cas9 System.

The CRISPR (clustered regularly interspaced short palindromic repeats)/Cas9 system has emerged as a powerful tool for precise and efficient gene editing in a variety of organisms. Centromere-associated protein-E (CENP-E) is a plus-end-directed kinesin required for kinetochore-microtubule capture, chromosome alignment, and spindle assembly checkpoint. Although cellular functions of the CENP-E proteins have been well studied, it has been difficult to study the direct functions of CENP-E proteins using traditional protocols because CENP-E ablation usually leads to spindle assembly checkpoint activation, cell cycle arrest, and cell death. In this study, we have completely knocked out the CENP-E gene in human HeLa cells and successfully generated the CENP-E-/- HeLa cells using the CRISPR/Cas9 system. Three optimized phenotype-based screening strategies were established, including cell colony screening, chromosome alignment phenotypes, and the fluorescent intensities of CENP-E proteins, which effectively improve the screening efficiency and experimental success rate of the CENP-E knockout cells. Importantly, CENP-E deletion results in chromosome misalignment, the abnormal location of the BUB1 mitotic checkpoint serine/threonine kinase B (BubR1) proteins, and mitotic defects. Furthermore, we have utilized the CENP-E knockout HeLa cell model to develop an identification method for CENP-E-specific inhibitors. In this study, a useful approach to validate the specificity and toxicity of CENP-E inhibitors has been established. Moreover, this paper presents the protocols of CENP-E gene editing using the CRISPR/Cas9 system, which could be a powerful tool to investigate the mechanisms of CENP-E in cell division. Moreover, the CENP-E knockout cell line would contribute to the discovery and validation of CENP-E inhibitors, which have important implications for antitumor drug development, studies of cell division mechanisms in cell biology, and clinical applications.

Kinesin-5 Eg5 is essential for spindle assembly, chromosome stability and organogenesis in development.

Chromosome stability relies on bipolar spindle assembly and faithful chromosome segregation during cell division. Kinesin-5 Eg5 is a plus-end-directed kinesin motor protein, which is essential for spindle pole separation and chromosome alignment in mitosis. Heterozygous Eg5 mutations cause autosomal-dominant microcephaly, primary lymphedema, and chorioretinal dysplasia syndrome in humans. However, the developmental roles and cellular mechanisms of Eg5 in organogenesis remain largely unknown. In this study, we have shown that Eg5 inhibition leads to the formation of the monopolar spindle, chromosome misalignment, polyploidy, and subsequent apoptosis. Strikingly, long-term inhibition of Eg5 stimulates the immune responses and the accumulation of lymphocytes in the mouse spleen through the innate and specific immunity pathways. Eg5 inhibition results in metaphase arrest and cell growth inhibition, and suppresses the formation of somite and retinal development in zebrafish embryos. Our data have revealed the essential roles of kinesin-5 Eg5 involved in cell proliferation, chromosome stability, and organogenesis during development. Our findings shed a light on the cellular basis and pathogenesis in microcephaly, primary lymphedema, and chorioretinal dysplasia syndrome of Eg5-mutation-positive patients.

Kinesin-7 CENP-E is essential for chromosome alignment and spindle assembly of mouse spermatocytes.

Genome stability depends on chromosome congression and alignment during cell division. Kinesin-7 CENP-E is critical for kinetochore-microtubule attachment and chromosome alignment, which contribute to genome stability in mitosis. However, the functions and mechanisms of CENP-E in the meiotic division of male spermatocytes remain largely unknown. In this study, by combining the use of chemical inhibitors, siRNA-mediated gene knockdown, immunohistochemistry, and high-resolution microscopy, we have found that CENP-E inhibition results in chromosome misalignment and metaphase arrest in dividing spermatocyte during meiosis. Strikingly, we have revealed that CENP-E regulates spindle organization in metaphase I spermatocytes and cultured GC-2 spd cells. CENP-E depletion leads to spindle elongation, chromosome misalignment, and chromosome instability in spermatocytes. Together, these findings indicate that CENP-E mediates the kinetochore recruitment of BubR1, spindle assembly checkpoint and chromosome alignment in dividing spermatocytes, which finally contribute to faithful chromosome segregation and chromosome stability in the male meiotic division.

Functional Assessment of Kinesin-7 CENP-E in Spermatocytes using In Vivo Inhibition, Immunofluorescence and Flow Cytometry.

In eukaryotes, meiosis is essential for genome stability and genetic diversity in sexual reproduction. Experimental analyses of spermatocytes in testes are critical for the investigations of spindle assembly and chromosome segregation in male meiotic division. The mouse spermatocyte is an ideal model for mechanistic studies of meiosis, however, the effective methods for the analyses of spermatocytes are lacking. In this article, a practical and efficient method for the in vivo inhibition of kinesin-7 CENP-E in mouse spermatocytes is reported. A detailed procedure for testicular injection of a specific inhibitor GSK923295 through abdominal surgery in 3-week-old mice is presented. Furthermore, described here is a series of protocols for tissue collection and fixation, hematoxylin-eosin staining, immunofluorescence, flow cytometry and transmission electron microscopy. Here we present an in vivo inhibition model via abdominal surgery and testicular injection, that could be a powerful technique to study male meiosis. We also demonstrate that CENP-E inhibition results in chromosome misalignment and metaphase arrest in primary spermatocytes during meiosis I. Our in vivo inhibition method will facilitate mechanistic studies of meiosis, serve as a useful method for genetic modifications of male germ lines, and shed a light on future clinical applications.

[The study of the expression and the prognostic value of Survivin and Ki67 in pancreatic endocrine tumors].

OBJECTIVE: To explore the relationship between the expression of Survivin and Ki67 with prognosis of pancreatic endocrine tumors (PETs). METHODS: Immunohistochemistry for Survivin and Ki67 was performed in 25 cases of normal pancreatic tissues and 81 cases of PETs by tissue microarrays and to observe the expression and evaluate the relationship with prognosis. RESULTS: (1)The expression of Survivin and Ki67 in PETs was significantly higher than that in normal pancreatic tissues (P <0.01); (2)The expression of Survivin and Ki67 in PETs was correlated with tissue grading and the TNM-staging (P < 0.05), but not related with tumor size, location and functional status. In addition, the expression of nuclear Survivin was association with lymph node metastasis (P < 0.05). (3)The high expression of Ki67 was related with the expression of nuclear Survivin, but not related with the expression of cytoplasmic Survivin. CONCLUSION: Survivin and Ki67 were both expressed in PETs, which were closely related to the clinical pathological characteristics. They could be used as new indicators in the evaluation of prognosis of PETs. The expression of Survivin in nucleus had more diagnostic significance than that in cytoplasm, and that could be highly correlated with lymph node metastasis, which would be used as a new marker of poor prognosis.

[The effect and mechanism of curcumin derivative B06 on the myocardium from type 2 diabetic rats].

OBJECTIVE: To investigate the protective effect and mechanism of curcumin derivatives B06 on myocardium from type 2 diabetic rats. METHODS: Thirty-five male SD rats were randomly divided into 5 groups, normal control group (NC group), high fat group (HF group), high fat treatment group (FT group), diabetes mellitus group (DM group) and diabetes treatment group (DT group) (n = 7). The late four groups were fed with high fat food, after four weeks of high fat feeding, the rats from DM group and DT group were injected with low dosage of streptozocin intraperitoneally to induce diabetes mellitus, FT group and DT group were gavaged with curcumin derivatives B06 at the dosage of 0.2 mg/kg x d. The blood glucose and lipid were detected biochemically, blood insulin was assayed by ELISA and the insulin resistance index was calculated, the morphology of myocardium was observed by light and transmission electron microscopy, the protein expression of AMP-activated protein kinase alpha (AMPKalpha) and phosphorylated AMP-activated protein kinase alpha (p-AMPKalpha) in myocardium were tested by Western blot. RESULTS: The level of blood glucose, lipid, insulin and the insulin resistance index were increased in HF group and DM group, but they were decreased after the treatment with B06. The expression of AMPKalpha and p-AMPKalpha were decreased, but they became increased after the treatment of B06. There were increased collagen fibers in interstitium and expansion of mitochondria in cytoplasm of myocardium from DM group, but they were ameliorated in B06 treatment group. CONCLUSION: It is suggested that B06 may relieve the damage of myocardium from type 2 diabetic rats and the increased expression of AMPKalpha and p-AMPKalpha may be involved in it.