MAP9/MAPH-9 supports axonemal microtubule doublets and modulates motor movement.

Microtubule doublets (MTDs) comprise an incomplete microtubule (B-tubule) attached to the side of a complete cylindrical microtubule. These compound microtubules are conserved in cilia across the tree of life; however, the mechanisms by which MTDs form and are maintained in vivo remain poorly understood. Here, we identify microtubule-associated protein 9 (MAP9) as an MTD-associated protein. We demonstrate that C. elegans MAPH-9, a MAP9 homolog, is present during MTD assembly and localizes exclusively to MTDs, a preference that is in part mediated by tubulin polyglutamylation. We find that loss of MAPH-9 causes ultrastructural MTD defects, including shortened and/or squashed B-tubules with reduced numbers of protofilaments, dysregulated axonemal motor velocity, and perturbed cilia function. Because we find that the mammalian ortholog MAP9 localizes to axonemes in cultured mammalian cells and mouse tissues, we propose that MAP9/MAPH-9 plays a conserved role in regulating ciliary motors and supporting the structure of axonemal MTDs.

Argentine ant extract induces an osm-9 dependent chemotaxis response in C. elegans.

Many ant species are equipped with chemical defenses, although how these compounds impact nervous system function is unclear. Here, we examined the utility of Caenorhabditis elegans chemotaxis assays for investigating how ant chemical defense compounds are detected by heterospecific nervous systems. We found that C. elegans respond to extracts from the invasive Argentine Ant ( Linepithema humile ) and the osm-9 ion channel is required for this response. Divergent strains varied in their response to L. humile extracts, suggesting genetic variation underlying chemotactic responses. These experiments were conducted by an undergraduate laboratory course, highlighting how C. elegans chemotaxis assays in a classroom setting can provide genuine research experiences and reveal new insights into interspecies interactions.

MAP9/MAPH-9 supports axonemal microtubule doublets and modulates motor movement.

Microtubule doublets (MTDs) are a well conserved compound microtubule structure found primarily in cilia. However, the mechanisms by which MTDs form and are maintained in vivo remain poorly understood. Here, we characterize microtubule-associated protein 9 (MAP9) as a novel MTD-associated protein. We demonstrate that C. elegans MAPH-9, a MAP9 homolog, is present during MTD assembly and localizes exclusively to MTDs, a preference that is in part mediated by tubulin polyglutamylation. Loss of MAPH-9 caused ultrastructural MTD defects, dysregulated axonemal motor velocity, and perturbed cilia function. As we found that the mammalian ortholog MAP9 localized to axonemes in cultured mammalian cells and mouse tissues, we propose that MAP9/MAPH-9 plays a conserved role in supporting the structure of axonemal MTDs and regulating ciliary motors.

Separable mechanisms drive local and global polarity establishment in the Caenorhabditiselegans intestinal epithelium.

Apico-basolateral polarization is essential for epithelial cells to function as selective barriers and transporters, and to provide mechanical resilience to organs. Epithelial polarity is established locally, within individual cells to establish distinct apical, junctional and basolateral domains, and globally, within a tissue where cells coordinately orient their apico-basolateral axes. Using live imaging of endogenously tagged proteins and tissue-specific protein depletion in the Caenorhabditiselegans embryonic intestine, we found that local and global polarity establishment are temporally and genetically separable. Local polarity is initiated prior to global polarity and is robust to perturbation. PAR-3 is required for global polarization across the intestine but local polarity can arise in its absence, as small groups of cells eventually established polarized domains in PAR-3-depleted intestines in a HMR-1 (E-cadherin)-dependent manner. Despite the role of PAR-3 in localizing PKC-3 to the apical surface, we additionally found that PAR-3 and PKC-3/aPKC have distinct roles in the establishment and maintenance of local and global polarity. Taken together, our results indicate that different mechanisms are required for local and global polarity establishment in vivo.

Won't You be My Neighbor: How Epithelial Cells Connect Together to Build Global Tissue Polarity.

Epithelial tissues form continuous barriers to protect against external environments. Within these tissues, epithelial cells build environment-facing apical membranes, junction complexes that anchor neighbors together, and basolateral surfaces that face other cells. Critically, to form a continuous apical barrier, neighboring epithelial cells must align their apico-basolateral axes to create global polarity along the entire tissue. Here, we will review mechanisms of global tissue-level polarity establishment, with a focus on how neighboring epithelial cells of different origins align their apical surfaces. Epithelial cells with different developmental origins and/or that polarize at different times and places must align their respective apico-basolateral axes. Connecting different epithelial tissues into continuous sheets or tubes, termed epithelial fusion, has been most extensively studied in cases where neighboring cells initially dock at an apical-to-apical interface. However, epithelial cells can also meet basal-to-basal, posing several challenges for apical continuity. Pre-existing basement membrane between the tissues must be remodeled and/or removed, the cells involved in docking are specialized, and new cell-cell adhesions are formed. Each of these challenges can involve changes to apico-basolateral polarity of epithelial cells. This minireview highlights several in vivo examples of basal docking and how apico-basolateral polarity changes during epithelial fusion. Understanding the specific molecular mechanisms of basal docking is an area ripe for further exploration that will shed light on complex morphogenetic events that sculpt developing organisms and on the cellular mechanisms that can go awry during diseases involving the formation of cysts, fistulas, atresias, and metastases.

Proximity labeling reveals non-centrosomal microtubule-organizing center components required for microtubule growth and localization.

Microtubules are polarized intracellular polymers that play key roles in the cell, including in transport, polarity, and cell division. Across eukaryotic cell types, microtubules adopt diverse intracellular organization to accommodate these distinct functions coordinated by specific cellular sites called microtubule-organizing centers (MTOCs). Over 50 years of research on MTOC biology has focused mainly on the centrosome; however, most differentiated cells employ non-centrosomal MTOCs (ncMTOCs) to organize their microtubules into diverse arrays, which are critical to cell function. To identify essential ncMTOC components, we developed the biotin ligase-based, proximity-labeling approach TurboID for use in C. elegans. We identified proteins proximal to the microtubule minus end protein PTRN-1/Patronin at the apical ncMTOC of intestinal epithelial cells, focusing on two conserved proteins: spectraplakin protein VAB-10B/MACF1 and WDR-62, a protein we identify as homologous to vertebrate primary microcephaly disease protein WDR62. VAB-10B and WDR-62 do not associate with the centrosome and instead specifically regulate non-centrosomal microtubules and the apical targeting of microtubule minus-end proteins. Depletion of VAB-10B resulted in microtubule mislocalization and delayed localization of a microtubule nucleation complex É£-tubulin ring complex (γ-TuRC), while loss of WDR-62 decreased the number of dynamic microtubules and abolished γ-TuRC localization. This regulation occurs downstream of cell polarity and in conjunction with actin. As this is the first report for non-centrosomal roles of WDR62 family proteins, we expand the basic cell biological roles of this important disease protein. Our studies identify essential ncMTOC components and suggest a division of labor where microtubule growth and localization are distinctly regulated.

Incidence of major adverse cardiovascular events among patients with provoked and unprovoked venous thromboembolism: Findings from the Registro Informatizado de Enfermedad Tromboembólica Registry.

OBJECTIVE: Overlap exists between the risk factors for coronary artery disease and venous thromboembolism (VTE). However, a paucity of data is available on the incidence of major acute cardiovascular events (MACE) and major adverse limb events (MALE) among patients presenting with VTE. Moreover, it is unknown whether the rate of cardiovascular outcomes differs among patients with unprovoked vs provoked VTE. METHODS: We analyzed the data from 2009 to 2017 in the Registro Informatizado de Enfermedad Tromboembólica registry, an ongoing, multicenter, international registry of consecutive patients with a diagnosis of objectively confirmed VTE. The query was restricted it to patients with data entry for the arterial outcomes. The baseline prevalence of coronary artery disease risk factors was compared between patients with provoked (ie, immobility, cancer, surgery, travel >6 hours, hormonal causes) and unprovoked VTE. After the initial VTE event, we followed up patients for the composite primary outcome of incident MACE (ie, stroke, myocardial infarction, unstable angina) and/or MALE (ie, major limb events). We used the χ2 test for baseline associations and a Cox proportional hazard for multivariate analysis. We used IBM SPSS, version 24 (IBM Corp, Armonk, NY) for statistical analysis. A P value of <.05 was considered statistically significant. RESULTS: We analyzed the data from 41,259 patients with VTE, of whom 22,633 (55.6%) had experienced a provoked VTE. During follow-up, the patients with provoked VTE were more likely to develop MACE or MALE than were patients with unprovoked VTE (hazard ratio [HR], 1.3; 95% confidence interval [CI], 1.1-1.5). The association of arterial events with recent immobility (HR, 1.4; 95% CI, 1.5-12.1) and cancer (HR, 1.7; 95% CI, 1.4-1.9) was strong. After adjusting for multiple conventional cardiovascular risk factors, provoked VTE, compared with unprovoked VTE, was significantly associated with an increased hazard for MACE (HR, 1.4; 95% CI, 1.1-1.7). Cancer remained a significant adjusted predictor for both MACE (HR, 1.7; 95% CI, 1.4-2.1) and MALE (HR, 2.1; 95% CI 1.01-4.6) in those with provoked VTE. CONCLUSIONS: Among patients with VTE, provoked cases, specifically those with cancer-associated VTE, have an increased risk of major arterial events.

Muscle functions as a connective tissue and source of extracellular matrix in planarians.

Regeneration and tissue turnover require new cell production and positional information. Planarians are flatworms capable of regenerating all body parts using a population of stem cells called neoblasts. The positional information required for tissue patterning is primarily harbored by muscle cells, which also control body contraction. Here we produce an in silico planarian matrisome and use recent whole-animal single-cell-transcriptome data to determine that muscle is a major source of extracellular matrix (ECM). No other ECM-secreting, fibroblast-like cell type was detected. Instead, muscle cells express core ECM components, including all 19 collagen-encoding genes. Inhibition of muscle-expressed hemicentin-1 (hmcn-1), which encodes a highly conserved ECM glycoprotein, results in ectopic peripheral localization of cells, including neoblasts, outside of the muscle layer. ECM secretion and hmcn-1-dependent maintenance of tissue separation indicate that muscle functions as a planarian connective tissue, raising the possibility of broad roles for connective tissue in adult positional information.

Orthogonal muscle fibres have different instructive roles in planarian regeneration.

The ability to regenerate missing body parts exists throughout the animal kingdom. Positional information is crucial for regeneration, but how it is harboured and used by differentiated tissues is poorly understood. In planarians, positional information has been identified from study of phenotypes caused by RNA interference in which the wrong tissues are regenerated. For example, inhibition of the Wnt signalling pathway leads to regeneration of heads in place of tails. Characterization of these phenotypes has led to the identification of position control genes (PCGs)-genes that are expressed in a constitutive and regional manner and are associated with patterning. Most PCGs are expressed within planarian muscle; however, how muscle is specified and how different muscle subsets affect regeneration is unknown. Here we show that different muscle fibres have distinct regulatory roles during regeneration in the planarian Schmidtea mediterranea. myoD is required for formation of a specific muscle cell subset: the longitudinal fibres, oriented along the anterior-posterior axis. Loss of longitudinal fibres led to complete regeneration failure because of defects in regeneration initiation. A different transcription factor-encoding gene, nkx1-1, is required for the formation of circular fibres, oriented along the medial-lateral axis. Loss of circular fibres led to a bifurcated anterior-posterior axis with fused heads forming in single anterior blastemas. Whereas muscle is often viewed as a strictly contractile tissue, these findings reveal that different muscle types have distinct and specific regulatory roles in wound signalling and patterning to enable regeneration.

Predictors of active cancer thromboembolic outcomes. RIETE experience of the Khorana score in cancer-associated thrombosis.

Even though the Khorana risk score (KRS) has been validated to predict against the development of VTE among patients with cancer, it has a low positive predictive value. It is also unknown whether the score predicts outcomes in patients with cancer with established VTE. We selected a cohort of patients with active cancer from the RIETE (Registro Informatizado Enfermedad TromboEmbolica) registry to assess the prognostic value of the KRS at inception in predicting the likelihood of VTE recurrences, major bleeding and mortality during the course of anticoagulant therapy. We analysed 7948 consecutive patients with cancer-associated VTE. Of these, 2253 (28 %) scored 0 points, 4550 (57 %) 1-2 points and 1145 (14 %) scored ≥3 points. During the course of anticoagulation, amongst patient with low, moderate and high risk KRS, the rate of VTE recurrences was of 6.21 (95 %CI: 4.99-7.63), 11.2 (95 %CI: 9.91-12.7) and 19.4 (95 %CI: 15.4-24.1) events per 100 patient-years; the rate of major bleeding of 5.24 (95 %CI: 4.13-6.56), 10.3 (95 %CI: 9.02-11.7) and 19.4 (95 %CI: 15.4-24.1) bleeds per 100 patient-years and the mortality rate of 25.3 (95 %CI: 22.8-28.0), 58.5 (95 %CI: 55.5-61.7) and 120 (95 %CI: 110-131) deaths per 100 patient-years, respectively. The C-statistic was 0.53 (0.50-0.56) for recurrent VTE, 0.56 (95 %CI: 0.54-0.59) for major bleeding and 0.54 (95 %CI: 0.52-0.56) for death. In conclusion, most VTEs occur in patients with low or moderate risk scores. The KRS did not accurately predict VTE recurrence, major bleeding, or mortality among patients with cancer-associated thrombosis.

Comparisons Between Upper and Lower Extremity Deep Vein Thrombosis: A Review of the RIETE Registry.

BACKGROUND: The outcome of patients with upper extremity deep vein thrombosis (UEDVT) has not been consistently compared with that in patients with lower extremity deep vein thrombosis (LEDVT). METHODS: We used the Registro Informatizado de Enfermedad Trombo Embólica (RIETE) registry to compare the outcomes during the course of anticoagulant therapy in patients with UEDVT versus outcomes in patients with LEDVT. RESULTS: As of August 2015, 37,366 patients with acute DVT had been enrolled in RIETE: 35094 (94%) had LEDVT, 1334 (3.6%) non-catheter related UEDVT (672 unprovoked and 662 provoked) and 938 (2.5%) had catheter-related UEDVT. During the course of anticoagulation, patients with unprovoked UEDVT had a higher rate of DVT recurrences (hazard ratio [HR]: 2.22; 95% CI: 1.37-3.43) and a similar rate of PE recurrences or major bleeding than those with unprovoked LEDVT. Patients with non-catheter-related provoked UEDVT had a similar outcome than those with provoked LEDVT. Among patients with UEDVT, those with non-catheter related unprovoked UEDVT had a lower rate of PE recurrences (HR: 0.06; 95% CI: 0-0.35) and major bleeding (HR: 0.20; 95% CI: 0.08-0.46) than those with catheter-related UEDVT or those with non-catheter related provoked UEDVT (HR: 0.10; 95% CI: 0.004-0.60; and 0.22; 95% CI: 0.08-0.52, respectively). On multivariable analysis, any difference had disappeared. CONCLUSION: During the course of anticoagulation, patients with UEDVT had a similar outcome than those with LEDVT. Among UEDVT patients, there were some differences according to the presence of catheter or additional risk factors for DVT. These differences disappeared after adjusting for potentially confounding variables.

Two FGFRL-Wnt circuits organize the planarian anteroposterior axis.

How positional information instructs adult tissue maintenance is poorly understood. Planarians undergo whole-body regeneration and tissue turnover, providing a model for adult positional information studies. Genes encoding secreted and transmembrane components of multiple developmental pathways are predominantly expressed in planarian muscle cells. Several of these genes regulate regional identity, consistent with muscle harboring positional information. Here, single-cell RNA-sequencing of 115 muscle cells from distinct anterior-posterior regions identified 44 regionally expressed genes, including multiple Wnt and ndk/FGF receptor-like (ndl/FGFRL) genes. Two distinct FGFRL-Wnt circuits, involving juxtaposed anterior FGFRL and posterior Wnt expression domains, controlled planarian head and trunk patterning. ndl-3 and wntP-2 inhibition expanded the trunk, forming ectopic mouths and secondary pharynges, which independently extended and ingested food. fz5/8-4 inhibition, like that of ndk and wntA, caused posterior brain expansion and ectopic eye formation. Our results suggest that FGFRL-Wnt circuits operate within a body-wide coordinate system to control adult axial positioning.

A Generic and Cell-Type-Specific Wound Response Precedes Regeneration in Planarians.

Regeneration starts with injury. Yet how injuries affect gene expression in different cell types and how distinct injuries differ in gene expression remain unclear. We defined the transcriptomes of major cell types of planarians--flatworms that regenerate from nearly any injury--and identified 1,214 tissue-specific markers across 13 cell types. RNA sequencing on 619 single cells revealed that wound-induced genes were expressed either in nearly all cell types or specifically in one of three cell types (stem cells, muscle, or epidermis). Time course experiments following different injuries indicated that a generic wound response is activated with any injury regardless of the regenerative outcome. Only one gene, notum, was differentially expressed early between anterior- and posterior-facing wounds. Injury-specific transcriptional responses emerged 30 hr after injury, involving context-dependent patterning and stem-cell-specialization genes. The regenerative requirement of every injury is different; however, our work demonstrates that all injuries start with a common transcriptional response.

A RIETE registry analysis of recurrent thromboembolism and hemorrhage in patients with catheter-related thrombosis.

BACKGROUND: Few studies have investigated the treatment and the outcomes of patients with catheter-related thrombosis (CRT). METHODS: The RIETE registry (Registro Informatizado de Enfermedad TromboEmbólica [Computerized Registry of Patients with Venous Thromboembolism]) is a prospective international registry of consecutive patients with objectively confirmed venous thromboembolism (VTE). We analyzed the characteristics, treatment, and outcomes of patients with CRT. RESULTS: Of 558 patients with CRT, 45 (8%) presented with a pulmonary embolism (PE) concomitantly. More patients had central line-associated thrombosis compared with port systems, but catheter type did not influence the risk of presenting with a PE. Patients with only CRT were more often prescribed low-molecular-weight heparin for the duration of their anticoagulant treatment compared with patients presenting with concomitant PE. VTE recurrences and major bleeding events occurred frequently during treatment with anticoagulation (7 per 100 patient-years and 8.9 per 100 patient years, respectively). The rates of fatal PE recurrences (1.85 per 100 patient-years) and fatal bleeding (2.32 per 100 patient-years) were similar. Patients with an additional transient risk factor for VTE had the lowest risk for VTE recurrences (odds ratio [OR], 0.07; 90% confidence interval [CI], 0.01-0.45) compared with patients with CRT and no additional transient risk factors. PE at presentation increased the risk of recurrent thrombosis by 2.4 times. Renal insufficiency was also an independent predictor of recurrent thrombosis (OR, 3.93; 90% CI, 2.0-7.7). The odds of recurrent thrombosis was decreased by 77% in patients who received anticoagulation therapy for >90 days compared with patients with a shorter treatment (OR, 0.23; 90% CI, 0.1-0.56). CONCLUSIONS: Concomitant PE occurs less frequently in CRT than lower extremity deep venous thrombosis, but it is associated with a worse outcome. CRT occurs in high-risk patients, and duration of anticoagulation must be predicated on balancing these risks.

Outcomes in neurosurgical patients who develop venous thromboembolism: a review of the RIETE registry.

OBJECTIVES: Registro Informatizado de Enfermedad TromboEmbólica (RIETE) database was used to investigate whether neurosurgical patients with venous thromboembolism (VTE) were more likely to die of bleeding or VTE and the influence of anticoagulation on these outcomes. METHODS: Clinical characteristics, treatment details, and 3-month outcomes were assessed in those who developed VTE after neurosurgery. RESULTS: Of 40 663 patients enrolled, 392 (0.96%) had VTE in less than 60 days after neurosurgery. Most patients in the cohort (89%) received initial therapy with low-molecular-weight heparin, (33% received subtherapeutic doses). In the first week, 10 (2.6%) patients died (8 with pulmonary embolism [PE], no bleeding deaths; P = .005). After the first week, 20 (5.1%) patients died (2 with fatal bleeding, none from PE). Overall, this cohort was more likely to develop a fatal PE than a fatal bleed (8 vs 2 deaths, P = .058). CONCLUSIONS: Neurosurgical patients developing VTE were more likely to die from PE than from bleeding in the first week, despite anticoagulation.

The relationship between long-range chromatin occupancy and polymerization of the Drosophila ETS family transcriptional repressor Yan.

ETS family transcription factors are evolutionarily conserved downstream effectors of Ras/MAPK signaling with critical roles in development and cancer. In Drosophila, the ETS repressor Yan regulates cell proliferation and differentiation in a variety of tissues; however, the mechanisms of Yan-mediated repression are not well understood and only a few direct target genes have been identified. Yan, like its human ortholog TEL1, self-associates through an N-terminal sterile α-motif (SAM), leading to speculation that Yan/TEL1 polymers may spread along chromatin to form large repressive domains. To test this hypothesis, we created a monomeric form of Yan by recombineering a point mutation that blocks SAM-mediated self-association into the yan genomic locus and compared its genome-wide chromatin occupancy profile to that of endogenous wild-type Yan. Consistent with the spreading model predictions, wild-type Yan-bound regions span multiple kilobases. Extended occupancy patterns appear most prominent at genes encoding crucial developmental regulators and signaling molecules and are highly conserved between Drosophila melanogaster and D. virilis, suggesting functional relevance. Surprisingly, although occupancy is reduced, the Yan monomer still makes extensive multikilobase contacts with chromatin, with an overall pattern similar to that of wild-type Yan. Despite its near-normal chromatin recruitment, the repressive function of the Yan monomer is significantly impaired, as evidenced by elevated target gene expression and failure to rescue a yan null mutation. Together our data argue that SAM-mediated polymerization contributes to the functional output of the active Yan repressive complexes that assemble across extended stretches of chromatin, but does not directly mediate recruitment to DNA or chromatin spreading.

Sterile alpha motif domain-mediated self-association plays an essential role in modulating the activity of the Drosophila ETS family transcriptional repressor Yan.

The ETS family transcriptional repressor Yan is an important downstream target and effector of the receptor tyrosine kinase (RTK) signaling pathway in Drosophila melanogaster. Structural and biochemical studies have shown that the N-terminal sterile alpha motif (SAM) of Yan is able to self associate to form a helical polymeric structure in vitro, although the extent and functional significance of self-association of full-length Yan remain unclear. In this study, we demonstrated that full-length Yan self associates via its SAM domain to form higher-order complexes in living cells. Introduction of SAM domain missense mutations that restrict Yan to a monomeric state reduces Yan's transcriptional repression activity and impairs its function during embryonic and retinal development. Coexpression of combinations of SAM domain mutations that permit the formation of Yan dimers, but not higher-order oligomers, increases activity relative to that of monomeric Yan, but not to the level obtained with wild-type Yan. Mechanistically, self-association directly promotes transcriptional repression of target genes independent of its role in limiting mitogen-activated protein kinase (MAPK)-mediated phosphorylation and nuclear export of Yan. Thus, we propose that the formation of higher-order Yan oligomers contributes to proper repression of target gene expression and RTK signaling output in developing tissues.