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Katsutoshi Mizuno, Erin E Dymek, Elizabeth F Smith
The complex waveforms characteristic of motile eukaryotic cilia and flagella are produced by the temporally and spatially regulated action of multiple dynein subforms generating sliding between subsets of axonemal microtubules. Multiple protein complexes have been identified that are associated with the doublet microtubules and that mediate regulatory signals between key axonemal structures, such as the radial spokes and central apparatus, and the dynein arm motors; these complexes include the N-DRC, MIA and CSC complexes...
October 22, 2016: Cytoskeleton
Sylvia Neumann, Romain Chassefeyre, George E Campbell, Sandra E Encalada
In axons, proper localization of proteins, vesicles, organelles, and other cargoes is accomplished by the highly regulated coordination of kinesins and dyneins, molecular motors that bind to cargoes and translocate them along microtubule (MT) tracks. Impairment of axonal transport is implicated in the pathogenesis of multiple neurodegenerative disorders including Alzheimer's and Huntington's diseases. To understand how MT-based cargo motility is regulated and to delineate its role in neurodegeneration, it is critical to analyze the detailed dynamics of moving cargoes inside axons...
October 22, 2016: Traffic
Thomas D Loreng, Elizabeth F Smith
The motile cilium is a complex organelle that is typically comprised of a 9+2 microtubule skeleton; nine doublet microtubules surrounding a pair of central singlet microtubules. Like the doublet microtubules, the central microtubules form a scaffold for the assembly of protein complexes forming an intricate network of interconnected projections. The central microtubules and associated structures are collectively referred to as the central apparatus (CA). Studies using a variety of experimental approaches and model organisms have led to the discovery of a number of highly conserved protein complexes, unprecedented high-resolution views of projection structure, and new insights into regulation of dynein-driven microtubule sliding...
October 21, 2016: Cold Spring Harbor Perspectives in Biology
Weili Hong, Anjneya Takshak, Olaolu Osunbayo, Ambarish Kunwar, Michael Vershinin
No abstract text is available yet for this article.
October 18, 2016: Biophysical Journal
Jacques Pécréaux, Stefanie Redemann, Zahraa Alayan, Benjamin Mercat, Sylvain Pastezeur, Carlos Garzon-Coral, Anthony A Hyman, Jonathon Howard
Precise positioning of the mitotic spindle is important for specifying the plane of cell division, which in turn determines how the cytoplasmic contents of the mother cell are partitioned into the daughter cells, and how the daughters are positioned within the tissue. During metaphase in the early Caenorhabditis elegans embryo, the spindle is aligned and centered on the anterior-posterior axis by a microtubule-dependent machinery that exerts restoring forces when the spindle is displaced from the center. To investigate the accuracy and stability of centering, we tracked the position and orientation of the mitotic spindle during the first cell division with high temporal and spatial resolution...
October 18, 2016: Biophysical Journal
Rose Gelineau-Morel, Marshall Lukacs, K Nicole Weaver, Robert B Hufnagel, Donald L Gilbert, Rolf W Stottmann
Whole exome sequencing continues to end the diagnostic odyssey for a number of patients and expands our knowledge of phenotypes associated with gene mutations. We describe an 11-year-old female patient with a constellation of symptoms including congenital cataracts, gut dysmotility, sensory neuropathy, and bifrontal polymicrogyria. Whole exome sequencing was performed and identified a de novo heterozygous missense mutation in the ATPase motor domain of cytoplasmic dynein heavy chain 1 (DYNC1H1), which is known to be involved in neuronal migration and retrograde axonal transport...
October 14, 2016: Genes
Pervez Ahmed Khoso, Tingru Pan, Na Wan, Zijiang Yang, Ci Liu, Shu Li
The aim of the present study was to investigate the effects of selenium (Se) deficiency on autophagy-related genes and on ultrastructural changes in the spleen, bursa of Fabricius, and thymus of chickens. The Se deficiency group was fed a basal diet containing Se at 0.033 mg/kg and the control group was fed the same basal diet containing Se at 0.15 mg/kg. The messenger RNA (mRNA) levels of the autophagy genes microtubule-associated protein 1 light chain 3 (LC3)-I, LC3-II, Beclin 1, dynein, autophagy associated gene 5 (ATG5), and target of rapamycin complex 1 (TORC1) were assessed using real-time qPCR...
October 15, 2016: Biological Trace Element Research
Nicholas J Bradshaw, Mirian A F Hayashi
NDE1 (Nuclear Distribution Element 1, also known as NudE) and NDEL1 (NDE-Like 1, also known as NudEL) are the mammalian homologues of the fungus nudE gene, with important and at least partially overlapping roles for brain development. While a large number of studies describe the various properties and functions of these proteins, many do not directly compare the similarities and differences between NDE1 and NDEL1. Although sharing a high degree structural similarity and multiple common cellular roles, each protein presents several distinct features that justify their parallel but also unique functions...
October 14, 2016: Cellular and Molecular Life Sciences: CMLS
Chun-Hong Wu, Qiong Zong, An-Li Du, Wei Zhang, Han-Chao Yao, Xiao-Qiang Yu, Yu-Feng Wang
Dynamitin (Dmn) is a major component of dynactin, a multiprotein complex playing important roles in a variety of intracellular motile events. We previously found that Wolbachia bacterial infection resulted in a reduction of Dmn protein. As Wolbachia may modify sperm in male hosts, we speculate that Dmn may have a function in male fertility. Here we used nosGal4 to drive Dmn knock down in testes of Drosophila melanogaster to investigate the functions of Dmn in spermatogenesis. We found that knockdown of Dmn in testes dramatically decreased male fertility, overexpression of Dmn in Wolbachia-infected males significantly rescued male fertility, indicating an important role of Dmn in inducing male fertility defects following Wolbachia infection...
October 11, 2016: Developmental Biology
Anil Nair, Sameep Chandel, Mithun K Mitra, Sudipto Muhuri, Abhishek Chaudhuri
Recent experiments have demonstrated that dynein motors exhibit catch bonding behavior, in which the unbinding rate of a single dynein decreases with increasing force, for a certain range of force. Motivated by these experiments, we study the effect of catch bonding on unidirectional transport properties of cellular cargo carried by multiple dynein motors. We introduce a threshold force bond deformation (TFBD) model, consistent with the experiments, wherein catch bonding sets in beyond a critical applied load force...
September 2016: Physical Review. E
Anjneya Takshak, Tanushree Roy, Parag Tandaiya, Ambarish Kunwar
Motor proteins are essential components of intracellular transport inside eukaryotic cells. These protein molecules use chemical energy obtained from hydrolysis of ATP to produce mechanical forces required for transporting cargos inside cells, from one location to another, in a directed manner. Of these motors, cytoplasmic dynein is structurally more complex than other motor proteins involved in intracellular transport, as it shows force and fuel (ATP) concentration dependent step-size. Cytoplasmic dynein motors are known to work in a team during cargo transport and force generation...
October 11, 2016: Protein Science: a Publication of the Protein Society
Amalia R Driller-Colangelo, Karen W L Chau, Jessica M Morgan, Nathan D Derr
Cytoplasmic dynein is a minus-end directed microtubule-based motor protein that drives intracellular cargo transport in eukaryotic cells. Although many intracellular cargos are propelled by small groups of dynein motors, the biophysical mechanisms governing ensemble motility remain largely unknown. To investigate the emergent motility of motor ensembles, we have designed a programmable DNA origami synthetic cargo "chassis" enabling us to control the number of dynein motors in the ensemble and vary the rigidity of the cargo chassis itself...
October 8, 2016: Cytoskeleton
Charles B Lindemann, Kathleen A Lesich
The eukaryotic flagellum is the organelle responsible for the propulsion of the male gamete in most animals. Without exception, sperm of all mammalian species use a flagellum for swimming. The mammalian sperm has a centrally located 9 + 2 arrangement of microtubule doublets and hundreds of accessory proteins that together constitute an axoneme. However, they also possess several characteristic peri-axonemal structures that make the mammalian sperm tail function differently. These modifications include nine outer dense fibers (ODFs) that are paired with the nine outer microtubule doublets of the axoneme, and are anchored in a structure called the connecting piece located at the base...
October 6, 2016: Cytoskeleton
Vincent Portegijs, Lars-Eric Fielmich, Matilde Galli, Ruben Schmidt, Javier Muñoz, Tim van Mourik, Anna Akhmanova, Albert J R Heck, Mike Boxem, Sander van den Heuvel
During cell division, the mitotic spindle segregates replicated chromosomes to opposite poles of the cell, while the position of the spindle determines the plane of cleavage. Spindle positioning and chromosome segregation depend on pulling forces on microtubules extending from the centrosomes to the cell cortex. Critical in pulling force generation is the cortical anchoring of cytoplasmic dynein by a conserved ternary complex of Gα, GPR-1/2, and LIN-5 proteins in C. elegans (Gα-LGN-NuMA in mammals). Previously, we showed that the polarity kinase PKC-3 phosphorylates LIN-5 to control spindle positioning in early C...
October 2016: PLoS Genetics
Anna Melkov, Raju Baskar, Yehonatan Alcalay, Uri Abdu
Intrinsic cell microtubule (MT) polarity, together with molecular motors and adaptor proteins, determines mitochondrial polarized targeting and MT-dependent transport. In polarized cells, such as neurons, mitochondrial mobility and transport require the regulation of kinesin and dynein by two adaptor proteins, Milton and Miro. Recently, we found that dynein heavy chain 64C (Dhc64C) is the primary motor protein for both anterograde and retrograde transport of mitochondria in the Drosophila bristle. In this study, we revealed that a molecular lesion in the Dhc64C allele that reduced bristle mitochondrial velocity generated a variant that acts as a "slow" dynein in a MT gliding assay, indicative of dynein directly regulating mitochondrial transport...
October 5, 2016: Development
Neha Khetan, Chaitanya A Athale
Asters nucleated by Microtubule (MT) organizing centers (MTOCs) converge on chromosomes during spindle assembly in mouse oocytes undergoing meiosis I. Time-lapse imaging suggests that this centripetal motion is driven by a biased 'search-and-capture' mechanism. Here, we develop a model of a random walk in a drift field to test the nature of the bias and the spatio-temporal dynamics of the search process. The model is used to optimize the spatial field of drift in simulations, by comparison to experimental motility statistics...
October 2016: PLoS Computational Biology
Xiaolei Lan, Hua Gao, Fei Wang, Jie Feng, Jiwei Bai, Peng Zhao, Lei Cao, Songbai Gui, Lei Gong, Yazhuo Zhang
Pituitary adenomas exhibit a wide range of behaviors. The prediction of invasion or malignant behavior in pituitary adenomas remains challenging. The objective of the present study was to identify the genetic abnormalities associated with invasion in sporadic pituitary adenomas. In the present study, the exomes of six invasive pituitary adenomas (IPA) and six non-invasive pituitary adenomas (nIPA) were sequenced by whole-exome sequencing. Variants were confirmed by dideoxynucleotide sequencing, and candidate driver genes were assessed in an additional 28 pituitary adenomas...
October 2016: Oncology Letters
Courtney R Bone, Yu-Tai Chang, Natalie E Cain, Shaun P Murphy, Daniel A Starr
Cellular migrations through constricted spaces are a critical aspect of many developmental and disease processes including hematopoiesis, inflammation, and metastasis. A limiting factor in these events is nuclear deformation. Here, we establish an in vivo model where nuclei can be visualized while moving through constrictions and use it to elucidate mechanisms for nuclear migration. C. elegans hypodermal P-cell larval nuclei traverse a narrow space about 5% their width. This constriction is blocked by fibrous organelles, structures connecting the muscles to cuticle through P cells...
October 3, 2016: Development
Sarah Cheung, Charlotte M Thomas, David J Timson
FH22 has been previously identified as a calcium-binding protein from the common liver fluke, Fasciola hepatica. It is part of a family of at least four proteins in this organism which combine an EF-hand containing N-terminal domain with a C-terminal dynein light chain-like domain. Here we report further biochemical properties of FH22, which we propose should be renamed FhCaBP1 for consistency with other family members. Molecular modelling predicted that the two domains are linked by a flexible region and that the second EF-hand in the N-terminal domain is most likely the calcium ion binding site...
September 28, 2016: Experimental Parasitology
Hans Schnittler
Force generation in non-muscle cells is vital for many cellular and tissue functions. Force-generating mechanisms include actomyosin-mediated contraction, actin polymerization that drives plasma membrane protrusions and filopodia as well as kinesin- and dynein-controlled transport of vesicles and organelles along the microtubule cytoskeleton. The actomyosin-mediated contractility and actin remodeling in both epithelium and endothelium were shown to have significant impact on cell migration, shape change and formation and control of intercellular junctions...
September 28, 2016: Histochemistry and Cell Biology
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