Cilia are cellular projections that assemble on centriole-derived basal bodies. While cilia assembly is absolutely dependent on centrioles, it is not known to what extent they contribute to ...downstream events. The nematode
provides a unique opportunity to address this question, as centrioles do not persist at the base of mature cilia. Using fluorescence microscopy and electron tomography, we find that centrioles degenerate early during ciliogenesis. The transition zone and axoneme are not completely formed at this time, indicating that cilia maturation does not depend on intact centrioles. The hydrolethalus syndrome protein HYLS-1 is the only centriolar protein known to remain at the base of mature cilia and is required for intraflagellar transport trafficking. Surprisingly, targeted degradation of HYLS-1 after initiation of ciliogenesis does not affect ciliary structures. Taken together, our results indicate that while centrioles are essential to initiate cilia formation, they are dispensable for cilia maturation and maintenance.
Cilia are cellular projections that perform sensory and motile functions in eukaryotic cells. A defining feature of cilia is that they are evolutionarily ancient, yet not universally conserved. In ...this study, we have used the resulting presence and absence pattern in the genomes of diverse eukaryotes to identify a set of 386 human genes associated with cilium assembly or motility. Comprehensive tissue‐specific RNAi in Drosophila and mutant analysis in C. elegans revealed signature ciliary defects for 70–80% of novel genes, a percentage similar to that for known genes within the cluster. Further characterization identified different phenotypic classes, including a set of genes related to the cartwheel component Bld10/CEP135 and two highly conserved regulators of cilium biogenesis. We propose this dataset defines the core set of genes required for cilium assembly and motility across eukaryotes and presents a valuable resource for future studies of cilium biology and associated disorders.
Synopsis
Cilia are evolutionarily highly ancient structures, thought to date back to the last common ancestor of all eukaryotes. Here, a combination of comparative genomics and functional analysis in Drosophila and C. elegans was used to define and characterize the core set of genes involved in cilium assembly and motility across eukaryotes.
Phylogenetic profiling defines a core set of 386 genes associated with cilium assembly and motility.
Comprehensive tissue‐specific depletion and mutant analysis confirms ciliary association of novel genes in Drosophila and C. elegans and reveals candidates for further study.
CABLES1, CCDC6, and TEX9 are identified as novel components of a basal body module that is recruited by the centriolar cartwheel component Bld10/CEP135.
MAPK15 and ELMOD are highly conserved regulators of multiple steps in the initiation of ciliogenesis.
Identification of a core set of genes associated with cilium assembly and motility across eukaryotes uncovers novel components of the basal body and regulators of ciliogenesis initiation.
Proteins of the HORMA domain family play central, but poorly understood, roles in chromosome organization and dynamics during meiosis. In Caenorhabditis elegans, four such proteins (HIM-3, HTP-1, ...HTP-2, and HTP-3) have distinct but overlapping functions. Through combined biochemical, structural, and in vivo analysis, we find that these proteins form hierarchical complexes through binding of their HORMA domains to cognate peptides within their partners’ C-terminal tails, analogous to the “safety belt” binding mechanism of Mad2. These interactions are critical for recruitment of HIM-3, HTP-1, and HTP-2 to chromosome axes. HTP-3, in addition to recruiting the other HORMA domain proteins to the axis, plays an independent role in sister chromatid cohesion and double-strand break formation. Finally, we find that mammalian HORMAD1 binds a motif found both at its own C terminus and at that of HORMAD2, indicating that this mode of intermolecular association is a conserved feature of meiotic chromosome structure in eukaryotes.
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•HORMA proteins play central but mysterious roles in meiotic chromosome metabolism•In C. elegans and mammals, HORMA proteins assemble through head-to-tail interactions•Hierarchical assembly of HORMA domain proteins underlies chromosome axis structure•Disruption of specific binding interactions allows targeted analysis in vivo
Kim, Rosenberg, et al. find that the meiotic HORMA domain proteins in C. elegans assemble into complexes along the chromosome axis through head-to-tail binding interactions, which are likely conserved throughout eukaryotes. Hierarchical assembly of HORMA proteins underlies chromosome axis structure and is important for meiotic recombination and chromosome segregation.
The AAA+ family ATPase TRIP13 is a key regulator of meiotic recombination and the spindle assembly checkpoint, acting on signaling proteins of the conserved HORMA domain family. Here we present the ...structure of the Caenorhabditis elegans TRIP13 ortholog PCH-2, revealing a new family of AAA+ ATPase protein remodelers. PCH-2 possesses a substrate-recognition domain related to those of the protein remodelers NSF and p97, while its overall hexameric architecture and likely structural mechanism bear close similarities to the bacterial protein unfoldase ClpX. We find that TRIP13, aided by the adapter protein p31(comet), converts the HORMA-family spindle checkpoint protein MAD2 from a signaling-active 'closed' conformer to an inactive 'open' conformer. We propose that TRIP13 and p31(comet) collaborate to inactivate the spindle assembly checkpoint through MAD2 conformational conversion and disassembly of mitotic checkpoint complexes. A parallel HORMA protein disassembly activity likely underlies TRIP13's critical regulatory functions in meiotic chromosome structure and recombination.
In budding yeast, the monopolin complex mediates sister kinetochore cross‐linking and co‐orientation in meiosis I. The CK1δ kinase Hrr25 is critical for sister kinetochore co‐orientation, but its ...roles are not well understood. Here, we present the structures of Hrr25 and its complex with the monopolin subunit Mam1. Hrr25 possesses a “central domain” that packs tightly against the kinase C‐lobe, adjacent to the binding site for Mam1. Together, the Hrr25 central domain and Mam1 form a novel, contiguous embellishment to the Hrr25 kinase domain that affects Hrr25 conformational dynamics and enzyme kinetics. Mam1 binds a hydrophobic surface on the Hrr25 N‐lobe that is conserved in CK1δ‐family kinases, suggesting a role for this surface in recruitment and/or regulation of these enzymes throughout eukaryotes. Finally, using purified proteins, we find that Hrr25 phosphorylates the kinetochore receptor for monopolin, Dsn1. Together with our new structural insights into the fully assembled monopolin complex, this finding suggests that tightly localized Hrr25 activity modulates monopolin complex–kinetochore interactions through phosphorylation of both kinetochore and monopolin complex components.
Synopsis
Budding yeast that possesses the meiotic monopolin complex subunit Mam1 also expresses a CK1‐family kinase with a conserved “central” domain of unknown structure and function. The structure of Saccharomyces cerevisiae Hrr25 reveals that this domain associates with bound Mam1 to form a novel kinase recruitment/regulatory module.
Co‐crystal structure of the Hrr25:Mam1 complex shows that Mam1 binds a hydrophobic surface conserved in CK1δ‐family kinases.
The Hrr25 central domain and Mam1 together regulate kinase conformational dynamics and enzyme kinetics.
Hrr25 phosphorylates Dsn1, the kinetochore receptor for monopolin, suggests a specificity control mechanism for sister kinetochore cross‐linking by monopolin.
Co‐crystallization of the Hrr25 kinase and its monopolin complex binding partner Mam1 shows the mechanism of Hrr25 recruitment to kinetochores in meiosis I and suggests a conserved mode of CK1‐family kinase regulation.
Story Teller Su, Bo; Tang, Tiffany Y.; Winoto, Pinata
Proceedings of the 2018 ACM International Joint Conference and 2018 International Symposium on Pervasive and Ubiquitous Computing and Wearable Computers,
10/2018
Conference Proceeding
An augmented reality (AR) application, Story Teller, is designed to teach preschool children some Chinese words. In order to train their motor skill, holdable items are used as the AR markers, which ...can be combined to construct a story. To retain children's interest, varying stories may be presented in different location and time.
Abstract only
The AAA+ ATPase Pch2/TRIP13 is a key regulator of two related signaling protein families in eukaryotes, the meiotic HORMADs and the spindle checkpoint protein MAD2. These two families ...share a common domain, the HORMA domain, which can adopt two differently‐folded states: a signaling‐inactive “open” state and an active, peptide‐bound “closed” state. In the closed state, the C‐terminus of the HORMA domain, termed the “safety belt” region, wraps around a bound peptide to generate a topological linkage between the two proteins. To determine how Pch2/TRIP13 regulates HORMA domain protein function, we determined the crystal structures of Pch2/TRIP13 orthologs from
C. elegans
and
H. sapiens
.
C. elegans
PCH‐2 crystallizes in an asymmetric hexamer conformation, and
H. sapiens
TRIP13 crystallizes in a helical‐spiral conformation, with subunit‐subunit interfaces equivalent to those seen in
C. elegans
PCH‐2. Together, these structures reveal how ATP binding, hydrolysis, and release in the Pch2/TRIP13 hexamer power conformational changes that remodel substrate proteins. Further, we find that mammalian TRIP13, aided by the adapter protein p31(comet), converts MAD2 from its signaling‐active closed conformer to its inactive open conformer. We propose that TRIP13 partially unfolds the MAD2 C‐terminal safety belt region, allowing release of bound peptide and relaxation to the protein's open state. In the context of the spindle assembly checkpoint, TRIP13 and p31(comet) collaborate to recognize and disassemble mitotic checkpoint complexes, inactivating the checkpoint. A parallel HORMA protein complex disassembly activity likely underlies TRIP13's critical regulatory functions in meiotic chromosome structure and recombination, where it acts on the meiotic HORMAD proteins.
Support or Funding Information
The authors acknowledge support from the NIH (R01GM104141), the March of Dimes Foundation, and the Ludwig Institute for Cancer Research.
ObjectivesTo investigate factors associated with severe COVID-19 in people with idiopathic inflammatory myopathy (IIM).MethodsDemographic data, clinical characteristics and COVID-19 outcome severity ...of adults with IIM were obtained from the COVID-19 Global Rheumatology Alliance physician-reported registry. A 3-point ordinal COVID-19 severity scale was defined: (1) no hospitalisation, (2) hospitalisation (and no death) and (3) death. ORs were estimated using multivariable ordinal logistic regression. Sensitivity analyses were performed using a 4-point ordinal scale: (1) no hospitalisation, (2) hospitalisation with no oxygen (and no death), (3) hospitalisation with oxygen/ventilation (and no death) and 4) death.ResultsOf 348 patients, 48% were not hospitalised, 39% were hospitalised (and did not die) and 13% died. Older age (OR=1.59/decade, 95% CI 1.31 to 1.91), high disease activity (OR=3.50, 95% CI 1.25 to 9.83; vs remission), ≥2 comorbidities (OR=2.63, 95% CI 1.39 to 4.98; vs none), prednisolone-equivalent dose >7.5 mg/day (OR=2.40, 95% CI 1.09 to 5.28; vs no intake) and exposure to rituximab (OR=2.71, 95% CI 1.28 to 5.72; vs conventional synthetic disease-modifying antirheumatic drugs only) were independently associated with severe COVID-19. In addition to these variables, in the sensitivity analyses, male sex (OR range: 1.65–1.83; vs female) was also significantly associated with severe outcomes, while COVID-19 diagnosis after 1 October 2020 (OR range: 0.51–0.59; vs on/before 15 June 2020) was significantly associated with less severe outcomes, but these associations were not significant in the main model (OR=1.57, 95% CI 0.95 to 2.59; and OR=0.61, 95% CI 0.37 to 1.00; respectively).ConclusionsThis is the first large registry data on outcomes of COVID-19 in people with IIM. Older age, male sex, higher comorbidity burden, high disease activity, prednisolone-equivalent dose >7.5 mg/day and rituximab exposure were associated with severe COVID-19. These findings will enable risk stratification and inform management decisions for patients with IIM.
The AAA+ family ATPase TRIP13 is a key regulator of meiotic recombination and the spindle assembly checkpoint, acting on signaling proteins of the conserved HORMA domain family. Here we present the ...structure of the Caenorhabditis elegans TRIP13 ortholog PCH-2, revealing a new family of AAA+ ATPase protein remodelers. PCH-2 possesses a substrate-recognition domain related to those of the protein remodelers NSF and p97, while its overall hexameric architecture and likely structural mechanism bear close similarities to the bacterial protein unfoldase ClpX. We find that TRIP13, aided by the adapter protein p31(comet), converts the HORMA-family spindle checkpoint protein MAD2 from a signaling-active ‘closed’ conformer to an inactive ‘open’ conformer. We propose that TRIP13 and p31(comet) collaborate to inactivate the spindle assembly checkpoint through MAD2 conformational conversion and disassembly of mitotic checkpoint complexes. A parallel HORMA protein disassembly activity likely underlies TRIP13's critical regulatory functions in meiotic chromosome structure and recombination.
It is known that varying degrees of concentration could lead to the change of body property such as skin conductance level. Through our experiments in the present study, assuming concentration ...related to skin conductance level, we use skin conductance variety detected using a compact and wearable galvanic skin response (GSR) sensor to investigate the possible link between the degree of concentration and the level of skin conductance for college students involving one of the most favored daily activities-game playing. In our experiment, four adults (four men) completed a specific mode of web-based game requiring a certain degree of concentration. Mixed results had been obtained. Preliminary results revealed that when players are concentrated (exhibited by relatively low level of skin conductance value), their performance tends to be better. Our results also showed that such pattern might vary as a function of both internal and external factors; no conclusive results can be obtained on whether skin conductance can be used a reliable in situ marker for the degree of concentration. Despite these, our study serves as a preliminary yet promising one down the research path.
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