Dense multicilia in higher vertebrates are important for luminal flow and the removal of thick mucus. To generate hundreds of basal bodies for multiciliogenesis, specialized terminally differentiated epithelial cells undergo massive centriole amplification. In proliferating cells, however, centriole duplication occurs only once per cell cycle. How cells ensure proper regulation of centriole biogenesis in different contexts is poorly understood. We report that the centriole amplification is controlled by two duplicated genes, Cep63 and Deup1. Cep63 regulates mother-centriole-dependent centriole duplication. Deup1 governs deuterosome assembly to mediate large-scale de novo centriole biogenesis. Similarly to Cep63, Deup1 binds to Cep152 and then recruits Plk4 to activate centriole biogenesis. Phylogenetic analyses suggest that Deup1 diverged from Cep63 in a certain ancestor of lobe-finned fishes during vertebrate evolution and was subsequently adopted by tetrapods. Thus, the Cep63 gene duplication has enabled mother-centriole-independent assembly of the centriole duplication machinery to satisfy different requirements for centriole number.

We present experimental studies on ion acceleration from ultra-thin diamond-like carbon (DLC) foils irradiated by ultra-high contrast laser pulses of energy 0.7 J focussed to peak intensities of 5 × 10 19 W/cm 2 . A reduction in electron heating is observed when the laser polarization is changed from linear to circular, leading to a pronounced peak in the fully ionized carbon spectrum at the optimum foil thickness of 5.3 nm. Two-dimensional particle-in-cell (PIC) simulations reveal, that those C 6+ ions are for the first time dominantly accelerated in a phase-stable way by the laser radiation pressure.

Ciliogenesis requires the removal of CP110 from the mother centriole; actin dynamics also influence ciliation, at least partly by affecting the centrosomal accumulation of ciliogenic membrane vesicles. How these distinct processes are properly regulated remains unknown. Here we show that miR-129-3p, a microRNA conserved in vertebrates, controlled cilia biogenesis in cultured cells by concomitantly downregulating CP110 and repressing branched F-actin formation. Blocking miR-129-3p inhibited serum-starvation-induced ciliogenesis, whereas its overexpression potently induced ciliation in proliferating cells and also promoted cilia elongation. Gene expression analysis further identified ARP2, TOCA1, ABLIM1 and ABLIM3 as its targets in ciliation-related actin dynamics. Moreover, miR-129-3p inhibition in zebrafish embryos suppressed ciliation in Kupffer's vesicle and the pronephros, and induced developmental abnormalities including a curved body, pericardial oedema and defective left-right asymmetry. Therefore, our results reveal a mechanism that orchestrates both the centriole-to-basal body transition and subsequent cilia assembly through microRNA-mediated post-transcriptional regulation.

Nudel and Lis1 appear to regulate cytoplasmic dynein in neuronal migration and mitosis through direct interactions. However, whether or not they regulate other functions of dynein remains elusive. Herein, overexpression of a Nudel mutant defective in association with either Lis1 or dynein heavy chain is shown to cause dispersions of membranous organelles whose trafficking depends on dynein. In contrast, the wild-type Nudel and the double mutant that binds to neither protein are much less effective. Time-lapse microscopy for lysosomes reveals significant reduction in both frequencies and velocities of their minus end–directed motions in cells expressing the dynein-binding defective mutant, whereas neither the durations of movement nor the plus end–directed motility is considerably altered. Moreover, silencing Nudel expression by RNA interference results in Golgi apparatus fragmentation and cell death. Together, it is concluded that Nudel is critical for dynein motor activity in membrane transport and possibly other cellular activities through interactions with both Lis1 and dynein heavy chain.

The anchoring of microtubules (MTs) to subcellular structures is critical for cell shape, polarity, and motility. In mammalian cells, the centrosome is a prominent MT anchoring structure. A number of proteins, including ninein, p150Glued , and EB1, have been implicated in centrosomal MT anchoring, but the process is far from understood. Here we show that CAP350 and FOP (FGFR1 oncogene partner) form a centrosomal complex required for MT anchoring. We show that the C-terminal domain of CAP350 interacts directly with FOP and that both proteins localize to the centrosome throughout the cell cycle. FOP also binds to EB1 and is required for localizing EB1 to the centrosome. Depletion of either CAP350, FOP, or EB1 by siRNA causes loss of MT anchoring and profound disorganization of the MT network. These results have implications for the mechanisms underlying MT anchoring at the centrosome and they attribute a key MT anchoring function to two novel centrosomal proteins, CAP350 and FOP. INTRODUCTIONIn most animal cells, the centrosome plays an important role in the organization of MT networks (Rieder et al., 2001;Bornens, 2002;Nigg, 2004;Ou and Rattner, 2004;Doxsey et al., 2005). A single centrosome is composed of two centrioles that are surrounded by amorphous pericentriolar material (PCM). These two centrioles (sometimes referred to as mother and daughter) differ in structure, function and age (state of maturity). In particular, the fully mature centriole is characterized by the presence of appendages at its distal end. MTs are nucleated from so-called ␥-tubulin ring complexes (␥-TuRCs; Moritz et al., 2004). These ring-shaped multiprotein complexes are present within PCM associated with both mother and daughter centrioles and, indeed, both centrioles are competent to nucleate MTs . Subsequent to nucleation, MTs are released (Keating et al., 1997;Abal et al., 2002). So, in order to remain associated with centrosomes, they need to be captured by centrosomal MT anchoring activities (Dammermann et al., 2003). Anchoring mechanisms remain incompletely understood, but the available evidence suggests that appendages of the mature centriole play a prominent role in MT anchoring . Moreover, transport of released MTs to appendages was shown to require dynein/dynactin activity Clark and Meyer, 1999;Quintyne et al., 1999).Several proteins have been shown to localize to centriole appendages. These include ninein (Mogensen et al., 2000), odf2/cenexin (Lange and Gull, 1995;Nakagawa et al., 2001;Ishikawa et al., 2005), centriolin (Gromley et al., 2003), ⑀-tubulin (Chang et al., 2003), Cep170 (Guarguaglini et al., 2005), and CEP110 (Ou et al., 2002). An involvement in MT anchoring has been clearly demonstrated for ninein (Mogensen et al., 2000;Dammermann and Merdes, 2002;Abal et al., 2002;Delgehyr et al., 2005). However, not all proteins implicated in MT anchoring are concentrated at appendages. In particular, evidence for a role in MT anchoring has been reported for PCM-1 (Dammermann and Merdes, 2002), BBS4 (Kim et al., 2004), and CEP1...

Ultraintense laser pulses with a few-cycle rising edge are ideally suited to accelerating ions from ultrathin foils, and achieving such pulses in practice represents a formidable challenge. We show that such pulses can be obtained using sufficiently strong and well-controlled relativistic nonlinearities in spatially well-defined near-critical-density plasmas. The resulting ultraintense pulses with an extremely steep rising edge give rise to significantly enhanced carbon ion energies consistent with a transition to radiation pressure acceleration.

Emerging evidence supports the idea that a signaling pathway containing orthologs of at least mammalian NudE and Nudel, Lis1, and cytoplasmic dynein is conserved for eukaryotic nuclear migration. In mammals, this pathway has profound impact on neuronal migration during development of the central nervous system. Lis1 and dynein are also involved in other cellular functions, such as mitosis. Here we show that Nudel also participates in a subset of dynein function in M phase. Nudel was specifically phosphorylated in M phase in its serine/threonine phosphorylation motifs, probably by Cdc2 and also Erk1 and -2. A fraction of Nudel bound to centrosomes strongly in interphase and localized to mitotic spindles in early M phase. By using mutants incapable of or simulating phosphorylation, we confirmed that phosphorylation of Nudel regulated the cellcycle-dependent distribution, possibly by increasing its dissociation rate at the microtubule-organizing center. Moreover, phosphorylated Nudel or the phosphorylation-mimicking mutant bound Lis1 more efficiently. We further demonstrated that a Nudel mutant incapable of binding to Lis1 impaired the poleward movement of dynein and hence the dynein-mediated transport of kinetochore proteins to spindle poles along microtubules, a process contributing to inactivation of the spindle checkpoint in mitosis. These results point to the importance of Nudel-Lis1 interaction for the dynein activity in M phase and to a possible role of Nudel phosphorylation as facilitating such interaction. In addition, comparative studies suggest that NudE is also functionally related to its paralog, Nudel.

Cilia are cellular protrusions containing nine microtubule (MT) doublets and function to propel cell movement or extracellular liquid flow through beating or sense environmental stimuli through signal transductions. Cilia require the central pair (CP) apparatus, consisting of two CP MTs covered with projections of CP proteins, for planar strokes. How the CP MTs of such ‘9 + 2’ cilia are constructed, however, remains unknown. Here we identify Spef1, an evolutionarily conserved microtubule-bundling protein, as a core CP MT regulator in mammalian cilia. Spef1 was selectively expressed in mammalian cells with 9 + 2 cilia and specifically localized along the CP. Its depletion in multiciliated mouse ependymal cells by RNAi completely abolished the CP MTs and markedly attenuated ciliary localizations of CP proteins such as Hydin and Spag6, resulting in rotational beat of the ependymal cilia. Spef1, which binds to MTs through its N-terminal calponin-homologous domain, formed homodimers through its C-terminal coiled coil region to bundle and stabilize MTs. Disruption of either the MT-binding or the dimerization activity abolished the ability of exogenous Spef1 to restore the structure and functions of the CP apparatus. We propose that Spef1 bundles and stabilizes central MTs to enable the assembly and functions of the CP apparatus.