CENP-F stabilizes kinetochore-microtubule attachments and limits dynein stripping of corona cargoes

Accurate chromosome segregation demands efficient capture of microtubules by kinetochores and their conversion to stable bioriented attachments that can congress and then segregate chromosomes. An early event is the shedding of the outermost fibrous corona layer of the kinetochore following microtubule attachment. Centromere protein F (CENP-F) is part of the corona, contains two microtubule-binding domains, and physically associates with dynein motor regulators. Here, we have combined CRISPR gene editing and engineered separation-of-function mutants to define how CENP-F contributes to kinetochore function. We show that the two microtubule-binding domains make distinct contributions to attachment stability and force transduction but are dispensable for chromosome congression. We further identify a specialized domain that functions to limit the dynein-mediated stripping of corona cargoes through a direct interaction with Nde1. This antagonistic activity is crucial for maintaining the required corona composition and ensuring efficient kinetochore biorientation

JavaGRID: Providing Simplified Access to Widely Distributed Computing

Presented for Consideration to the Conference on High Performance Distributed Computing Samuel H. Russ, Srikanth Batchu, Sonetra Howard, and Saneedp Musinipally Mississippi State University NSF Engineering Research Center for Computational Field Simulation Abstract ---- The era of rapid, easy access to remote computer resources is rapidly ap- proaching. Systems and collaborative efforts have been launched to experiment and determine how widely distributed, loosely coupled computing resources can be harnessed and man- aged efficiently and effectively. Such systems are sometimes called a "grid" or "information power grid". This paper discusses a grid architecture that promotes widely distributed com- puting among scientific programmers by making both access to remote resources and admins- tiration of remote users extremely simple. The architecture leverages the portability of Java, the Web, and MPI, and provides a platform for experimenting with regional--scale grids and "intrag..

Multimodal microtubule binding by the Ndc80 kinetochore complex.

The Ndc80 complex is a key site of kinetochore-microtubule attachment during cell division. The human complex engages microtubules with a globular head formed by tandem calponin-homology domains and an 80-amino-acid unstructured tail that contains sites of phosphoregulation by the Aurora B kinase. Using biochemical, cell biological and electron microscopy analyses, we dissected the roles of the tail in binding of microtubules and mediation of cooperative interactions between Ndc80 complexes. Two segments of the tail that contain Aurora B phosphorylation sites become ordered at interfaces; one with tubulin and the second with an adjacent Ndc80 head on the microtubule surface, forming interactions that are disrupted by phosphorylation. We propose a model in which Ndc80s interaction with either growing or shrinking microtubule ends can be tuned by the phosphorylation state of its tail

A two-week pilot study of intranasal oxytocin for cocaine-dependent individuals receiving methadone maintenance treatment for opioid use disorder

30-60% of patients receiving methadone for opioid use disorder (OUD) actively use cocaine. Cocaine use disorder (CUD) has no FDA-approved pharmacological treatment; existing psychosocial treatments are inadequate. Oxytocin, a social neuropeptide, has preclinical promise as an adjunctive treatment for both OUD and CUD. Twenty-two individuals receiving methadone for OUD with co-occurring CUD were randomized to receive oxytocin or placebo intranasally 40 IU twice daily for two weeks. A priori aims were feasibility and safety. Exploratory effectiveness aims included laboratory-based measures of drug craving, drug-related implicit cognition, and drug use. High retention rates (93.5%), the absence of study-related adverse events, and the fact that oxytocin was well tolerated in this population support the feasibility of larger trials. Two weeks of oxytocin (but not placebo) significantly reduced cocaine craving at day 15 compared to baseline (mean change±SD: OT=-0.23±0.19, p=0.004; PL=-0.16±0.29, p=0.114). For heroin craving, the placebo group reported a trend-level increase over time while the oxytocin group remained unchanged - with medium to large effect sizes between the groups (Cohen's d=0.71-0.90). Oxytocin led to a significant switch from implicit self-association with drugs to implicitly associating drugs with others (mean change±SD: 0.25±0.35, p=0.037) and a trend-level reduction in self-reported cocaine use over time (Z=-1.78, p=0.075). Furthermore, oxytocin significantly increased the accuracy of self-reported cocaine use when correlated with quantitative urine levels of cocaine metabolite. This proof-of-concept study provides promising early evidence that oxytocin may be an effective adjunct to the treatment of co-occurring CUD and OUD. Further investigation with larger trials is warranted

Mitotic redistribution of the mitochondrial network by Miro and Cenp-F

Although chromosome partitioning during mitosis is well studied, the molecular mechanisms that allow proper segregation of cytoplasmic organelles in human cells are poorly understood. Here we show that mitochondria interact with growing microtubule tips and are transported towards the daughter cell periphery at the end of mitosis. This phenomenon is promoted by the direct and cell cycle-dependent interaction of the mitochondrial protein Miro and the cytoskeletal-associated protein Cenp-F. Cenp-F is recruited to mitochondria by Miro at the time of cytokinesis and associates with microtubule growing tips. Cells devoid of Cenp-F or Miro show decreased spreading of the mitochondrial network as well as cytokinesis-specific defects in mitochondrial transport towards the cell periphery. Thus, Miro and Cenp-F promote anterograde mitochondrial movement and proper mitochondrial distribution in daughter cells

The Microtubule Binding Properties of CENP-E's C-Terminus and CENP-F

CENP-E (Centromere Protein E) and CENP-F, also known as mitosin, are large, multi-functional proteins associated with the outer kinetochore. CENP-E features a well-characterized kinesin motor domain at its N-terminus and a second microtubule-binding domain at its C-terminus of unknown function. CENP-F is important for the formation of proper kinetochore-microtubule attachment and, like CENP-E, contains two microtubule-binding domains at its termini. While the importance of these proteins is known, the details of their interactions with microtubules have not yet been investigated. We have biochemically and structurally characterized the microtubule-binding properties of the amino- and carboxyl-terminal domains of CENP-F as well as the carboxyl-terminal (non-kinesin) domain of CENP-E. CENP-E’s C-terminus and CENP-F’s N-terminus bind microtubules with similar affinity to the well-characterized Ndc80 complex, while CENP-F’s C-terminus shows much lower affinity. Electron microscopy analysis reveals that all of these domains engage the microtubule surface in a disordered manner, suggesting that these factors have no favored binding geometry and may allow for initial side-on attachments early in mitosis