Topoisomerase I is an Evolutionarily Conserved Key Regulator for Satellite DNA Transcription.

Repetitive satellite DNAs, divergent in nucleic-acid sequence and size across eukaryotes, provide a physical site for centromere assembly to orchestrate chromosome segregation during the cell cycle. These non-coding DNAs are transcribed by RNA polymerase (RNAP) II and the transcription has been shown to play a role in chromosome segregation, but a little is known about the regulation of centromeric transcription, especially in higher organisms with tandemly-repeated-DNA-sequence centromeres. Using RNA interference knockdown, chemical inhibition and AID/IAA degradation, we show that Topoisomerase I (TopI), not TopII, promotes the transcription of α-satellite DNAs, the main type of satellite on centromeres in human cells. Mechanistically, TopI localizes to centromeres, binds RNAP II and facilitates RNAP II elongation on centromeres. Interestingly, in response to DNA double-stranded breaks (DSBs) induced by chemotherapy drugs or CRSPR/Cas9, α-satellite transcription is dramatically stimulated in a DNA damage checkpoint-independent but TopI-dependent manner. These DSB-induced α-satellite RNAs were predominantly derived from the α-satellite high-order repeats of human centromeres and forms into strong speckles in the nucleus. Remarkably, TopI-dependent satellite transcription also exists in mouse 3T3 and Drosophila S2 cells and in Drosophila larval imaginal wing discs and tumor tissues. Altogether, our findings herein reveal an evolutionally conserved mechanism with TopI as a key player for the regulation of satellite transcription at both cellular and animal levels.

CDK11 facilitates centromeric transcription to maintain centromeric cohesion during mitosis.

Actively-transcribing RNA polymerase (RNAP)II is remained on centromeres to maintain centromeric cohesion during mitosis, although it is largely released from chromosome arms. This pool of RNAPII plays an important role in centromere functions. However, the mechanism of RNAPII retention on mitotic centromeres is poorly understood. We here demonstrate that Cyclin-dependent kinase (Cdk)11 is involved in RNAPII regulation on mitotic centromeres. Consistently, we show that Cdk11 knockdown induces centromeric cohesion defects and decreases Bub1 on kinetochores, but the centromeric cohesion defects are partially attributed to Bub1. Furthermore, Cdk11 knockdown and the expression of its kinase-dead version significantly reduce both RNAPII and elongating RNAPII (pSer2) levels on centromeres and decrease centromeric transcription. Importantly, the overexpression of centromeric α-satellite RNAs fully rescues Cdk11-knockdown defects. These results suggest that the maintenance of centromeric cohesion requires Cdk11-facilitated centromeric transcription. Mechanistically, Cdk11 localizes on centromeres where it binds and phosphorylates RNAPII to promote transcription. Remarkably, mitosis-specific degradation of G2/M Cdk11-p58 recapitulates Cdk11-knockdown defects. Altogether, our findings establish Cdk11 as an important regulator of centromeric transcription and as part of the mechanism for retaining RNAPII on centromeres during mitosis.

Teaching Platform for Physical Training of Track and Field Events in Colleges and Universities Based on Data Mining Technology.

To a large extent, track and field sports require strong physical fitness of athletes, and athletes' physical fitness determines their competition results. With the improvement of people's living standards, athletes can get better nutritional supplements, but competition in track events has gradually become fierce, and physical fitness is extremely important for athletes. Physical training can improve athletes' endurance, sports coordination, and sensitivity, but coaches should arrange the training intensity reasonably, not exceeding the athlete's tolerance, to avoid problems such as overloading training causing athletes to be injured and sports age shortened. Traditional track and field training methods are no longer suitable for the physical development of modern athletes. This paper mainly studies the college track and field sports training teaching platform based on data mining technology. By using data mining technology, this paper constructs a track and field training platform in colleges and universities. Therefore, this paper designs a teaching platform for physical training in track and field events and puts the teaching platform into training teaching. It uses data mining technology to collect athletes' sports characteristics and analyze athletes. The physical parameters and movement norms of the people develop a personalized training program for them.

An emerging role of transcription in chromosome segregation: Ongoing centromeric transcription maintains centromeric cohesion.

Non-coding centromeres, which dictate kinetochore formation for proper chromosome segregation, are extremely divergent in DNA sequences across species but are under active transcription carried out by RNA polymerase (RNAP) II. The RNAP II-mediated centromeric transcription has been shown to facilitate the deposition of the centromere protein A (CENP-A) to centromeres, establishing a conserved and critical role of centromeric transcription in centromere maintenance. Our recent work revealed another role of centromeric transcription in chromosome segregation: maintaining centromeric cohesion during mitosis. Interestingly, this role appears to be fulfilled through ongoing centromeric transcription rather than centromeric transcripts. In addition, we found that centromeric transcription may not require some of the traditional transcription initiation factors, suggestive of "uniqueness" in its regulation. In this review, we discuss the novel role and regulation of centromeric transcription as well as the potential underlying mechanisms.

Centromeric transcription maintains centromeric cohesion in human cells.

Centromeric transcription has been shown to play an important role in centromere functions. However, lack of approaches to specifically manipulate centromeric transcription calls into question that the proposed functions are a direct consequence of centromeric transcription. By monitoring nascent RNAs, we found that several transcriptional inhibitors exhibited distinct, even opposing, efficacies on the suppression of ongoing gene and centromeric transcription in human cells, whereas under the same conditions, total centromeric RNAs were changed to a lesser extent. The inhibitor suppressing ongoing centromeric transcription weakened centromeric cohesion, whereas the inhibitor increasing ongoing centromeric transcription strengthened centromeric cohesion. Furthermore, expression of CENP-B DNA-binding domain or CENP-B knockdown moderately increased centromeric transcription without altering gene transcription; as a result, centromeric cohesion was accordingly strengthened. Targeting of the Kox1-KRAB domain with CENP-B DB to centromeres specifically decreased centromeric transcription and weakened centromeric cohesion. Thus, based on these findings, we propose that a major function of centromeric transcription is to maintain centromeric cohesion in human cells.

Multisite phosphorylation determines the formation of Ska-Ndc80 macro-complexes that are essential for chromosome segregation during mitosis.

The human Ska complex (Ska) localizing to both spindle microtubules and kinetochores is essential for proper chromosome segregation during mitosis. Although several mechanisms have been proposed to explain how Ska is recruited to kinetochores, it is still not fully understood. By analyzing Ska3 phosphorylation, we identified six critical Cdk1 sites, including the previously identified Thr358 and Thr360. Mutations of these sites to phospho-deficient alanine (6A) in cells completely abolished Ska3 localization to kinetochores and Ska functions in chromosome segregation. In vitro, Cdk1 phosphorylation on Ska enhanced WT, not phospho-deficient 6A, binding to Ndc80C. Strikingly, the phosphomimetic Ska 6D complex formed a stable macro-complex with Ndc80C, but Ska WT failed to do so. These results suggest that multisite Cdk1 phosphorylation-enabled Ska-Ndc80 binding is decisive for Ska localization to kinetochores and its functions. Moreover, we found that Ska decrease at kinetochores triggered by the microtubule-depolymerizing drug nocodazole is independent of Aurora B but can be overridden by Ska3 overexpression, suggestive of a role of spindle microtubules in promoting Ska kinetochore recruitment. Thus, based on the current and previous results, we propose that multisite Cdk1 phosphorylation is critical for the formation of Ska-Ndc80 macro-complexes that are essential for chromosome segregation.

Highly enantioselective electrosynthesis of C2-quaternary indolin-3-ones.

A highly enantioselective and direct synthesis of C2-quaternary indolin-3-ones from 2-arylindoles by combining electrochemistry and organocatalysis is described. Excellent enantioselectivities (up to 99% ee) and diastereoselectivities (>20 : 1) can be obtained through anodic oxidation in combination with asymmetric proline-catalyzed alkylation in an undivided cell under constant-current conditions.

SET binding to Sgo1 inhibits Sgo1-cohesin interactions and promotes chromosome segregation.

At anaphase onset, Sgo1 function of cohesion protection must be disabled to allow timely chromosome segregation, but how this is achieved is not fully understood. Here, we show that SET, a known PP2A inhibitor, directly binds to a domain in Sgo1 in close proximity to the cohesin-binding motif. The Sgo1-cohesin binding can be disrupted by SET in a dose-dependent manner in vitro as well as by SET overexpression in cells, suggesting that SET is also an inhibitor to the Sgo1-cohesin binding. Furthermore, the SET binding-deficient Sgo1 mutant fully supports centromeric cohesion protection but delays chromosome segregation, suggesting that the SET-Sgo1 binding is required for timely chromosome segregation. Moreover, overexpression of SET WT, not the Sgo1 binding-deficient mutant, exacerbates the occurrence of cohesion fatigue in MG132-arrested cells. Conversely, SET depletion delays it. Thus, we propose that a major function of SET during mitosis is to disrupt the Sgo1-cohesin interaction, thereby promoting centromeric cohesion de-protection and timely chromosome segregation at anaphase onset.

Multitasking Ska in Chromosome Segregation: Its Distinct Pools Might Specify Various Functions.

The human spindle and kinetochore associated (Ska) complex is required for proper mitotic progression. Extensive studies have demonstrated its important functions in both stable kinetochore-microtubule interactions and spindle checkpoint silencing. We suggest a model to explain how various Ska functions might be fulfilled by distinct pools of Ska at kinetochores. The Ndc80-loop pool of Ska is recruited by the Ndc80 loop, or together with some of its flanking sequences, and the recruitment is also dependent on Cdk1-mediated Ska3 phosphorylation. This pool seems to play a more important role in silencing the spindle checkpoint than stabilizing kinetochore-microtubule interactions. In contrast, the Ndc80-N-terminus pool of Ska is recruited by the N-terminal domains of Ndc80 and appears to be more important for stabilizing kinetochore-microtubule interactions. Here, we review and discuss the evidence that supports this model and suggest further experiments to test the functioning mechanisms of the Ska complex.

hsa-miR-7 Is a Potential Biomarker for Idiopathic Inflammatory Myopathies with Interstitial Lung Disease in Humans.

OBJECTIVES: microRNAs (miRNAs) have been identified as biomarkers for various diseases. However, the significance of circulating miRNAs for the diagnosis of idiopathic inflammatory myopathies (IIM) is still unknown. In this study, we aim to investigate the significance of miRNAs as potential biomarkers for predicting the patients with IIM and interstitial lung disease (ILD) METHODS: Total RNA was isolated from plasma of 43 IIM patients and 43 healthy people. The expression of miRNAs was analyzed by miRNA microarray and validated by qRT-PCR RESULTS: Microarray shows more differentially expressed circulating miRNAs found in IIM patients compared with healthy controls (P<0.05). qRT-PCR confirmed miR-7 and miR-21 showes significantly changed levels in plasma samples between IIM patients and healthy controls (P<0.05). However, only miR-7 was the sole miRNA lower expression in each IIM patient (P<0.05), which is also lower expression in IIM/ILD patients than that without ILD (P<0.05). The area under curve (AUC) for distinguishing IIM/ILD patients from IIM without ILD is 0.8978, and the 95% confidence interval is 0.7961 to 0.9995. The receiver operating characteristic (ROC) curve analysis showes miR-7 cutoff value is 0.0063. Further, AUC analysis showes both miR-7 and miR-21 have diagnostic value as biomarkers for IIM patients form health controls; however, miR-7 is more sensitive CONCLUSION: miR-7 is a potential biomarker as a diagnostic indicator for IIM patients and can be used to distinguish IIM/ILD patients from IIM without ILD.

Ska3 Phosphorylated by Cdk1 Binds Ndc80 and Recruits Ska to Kinetochores to Promote Mitotic Progression.

The spindle and kinetochore-associated (Ska) protein complex is required for accurate chromosome segregation during mitosis [1-6] and consists of two copies each of Ska1, Ska2, and Ska3 proteins [4, 7]. The Ska complex contains multiple microtubule-binding elements and promotes kinetochore-microtubule attachment [8-11]. The Ska1 C-terminal domain (CTD) recruits protein phosphatase 1 (PP1) to kinetochores to promote timely anaphase onset [12]. The Ska complex regulates, and is regulated by, Aurora B [13]. Aurora B phosphorylates both Ska1 and Ska3 to inhibit the kinetochore localization of the Ska complex [14]. Despite its multitude of functions at kinetochores, how the Ska complex itself is recruited to kinetochores is unclear. It is unknown whether any mitotic kinases positively regulate the localization of the Ska complex to kinetochores. Here, we show that Cdk1 phosphorylates Ska3 to promote its direct binding to the Ndc80 complex (Ndc80C), a core outer kinetochore component. We also show that this phosphorylation occurs specifically during mitosis and is required for the kinetochore localization of the Ska complex. Ska3 mutants deficient in Cdk1 phosphorylation are defective in kinetochore localization but retain microtubule localization. These mutants support chromosome alignment but delay anaphase onset. We propose that Ska3 phosphorylated by Cdk1 in mitosis binds to Ndc80C and recruits the Ska complex to kinetochores where Ska1 can bind both PP1 and microtubules to promote anaphase onset.

Synthesis, structure and a nucleophilic coordination reaction of Germanetellurones.

ß-Diketiminato cyclopentadienyl and ferrocenylethynyl germylenes LGeR (L = HC[C(Me)N-2,6-iPr2C6H3]2, R = Cp () and C[triple bond, length as m-dash]CFc ()) were prepared and utilized to synthesize the Ge[double bond, length as m-dash]Te bond species. Reactions of , , and LGeC[triple bond, length as m-dash]CPh () with an excess of Te powder proceeded in toluene under reflux successfully yielded germanetellurone L(R)GeTe (R = Cp (), C[triple bond, length as m-dash]CFc (), and C[triple bond, length as m-dash]CPh ()). Further reaction of with GeCl2·dioxane at -78 °C resulted in L(Cp)GeTe(GeCl2) (), the first example of a germylene germanetellurone adduct. Both compounds and contain two isomers that are generated by the simultaneous 1,2-H- and 1,3-H-shifts over the Cp ring at the Ge atom. The reactions of L(Me)GeE with AuC6F5·SC4H8 at room temperature led to pentafluorophenyl gold(i) germanethione and germaneselone compounds L(Me)GeE(AuC6F5) (E = S () and Se ()). The formation of compounds exhibits a rare nucleophilic coordination reaction pathway by the Ge[double bond, length as m-dash]E (E = S, Se, Te) bond towards the metal-containing Lewis acidic species. The structures of compounds , , and are studied by the NMR and/or IR spectroscopy and X-ray crystallography.