Mitochondrial Phosphoenolpyruvate Carboxykinase Regulates Metabolic Adaptation and Enables Glucose-Independent Tumor Growth.

Cancer cells adapt metabolically to proliferate under nutrient limitation. Here we used combined transcriptional-metabolomic network analysis to identify metabolic pathways that support glucose-independent tumor cell proliferation. We found that glucose deprivation stimulated re-wiring of the tricarboxylic acid (TCA) cycle and early steps of gluconeogenesis to promote glucose-independent cell proliferation. Glucose limitation promoted the production of phosphoenolpyruvate (PEP) from glutamine via the activity of mitochondrial PEP-carboxykinase (PCK2). Under these conditions, glutamine-derived PEP was used to fuel biosynthetic pathways normally sustained by glucose, including serine and purine biosynthesis. PCK2 expression was required to maintain tumor cell proliferation under limited-glucose conditions in vitro and tumor growth in vivo. Elevated PCK2 expression is observed in several human tumor types and enriched in tumor tissue from non-small-cell lung cancer (NSCLC) patients. Our results define a role for PCK2 in cancer cell metabolic reprogramming that promotes glucose-independent cell growth and metabolic stress resistance in human tumors.

[Mycotic aneurysms: a case report, clinical review, imaging appearances and management].

To report a clinical case of mycotic thoracic aortic aneurysm. To describe and illustrate the spectrum of MDCT findings, analysing the pathophysiology, diagnostic evaluation and therapeutic management. To emphasis the early non-invasive diagnosis as a way to overall survival improvement. A mycotic aneurysm is an uncommon vascular lesion resulting from arterial wall destruction by infection, generally involving the peripheral arteries or aorta and rarely the cerebral and visceral arteries. Defined as a lobulated saccular outpouching of the wall communicating with the lumen, it is surrounded by oedema, hematoma and/or fibro-inflammatory tissue. Due the non-specific and delayed - or even absent - manifestations, a high degree of clinical suspicion is necessary to achieve a timely treatment and prognosis improvement. In this setting, radiologic evaluation - mainly by MDCT angiography - is essential, allowing detection, characterization and complications assessment before treatment planning.

Pretende-se reportar um caso clínico de aneurisma micótico da aorta torácica; descrever e ilustrar o espectro de achados tomodensitométricos (TDM); rever a fisiopatologia, a avaliação diagnóstica e o tratamento; e enfatizar o diagnóstico não-invasivo precoce como forma de aumentar a sobrevivência. Um aneurisma micótico é uma lesão vascular infrequente que resulta da destruição da parede arterial por um processo infecioso, que geralmente afeta as artérias periféricas ou a aorta, e, raramente, as artérias cerebrais ou viscerais. É definida como uma protrusão sacular e lobulada da parede em comunicação com o lúmen arterial, rodeada por edema, hematoma e/ou tecido inflamatório. Atendendo às manifestações inespecíficas e tardias que a caracterizam, é necessário um elevado grau de suspeição para que se obtenha um tratamento atempado e se possa melhorar o prognóstico. Consequentemente, a avaliação imagiológica ­ particularmente o estudo angiográfico TDM ­ é essencial, permitindo a deteção, caracterização e avaliação de complicações, necessárias ao planeamento terapêutico.

Acute aortic syndrome: Spectrum of imaging appearances.

OBJECTIVES: The main objective of this paper is to illustrate and analyse the spectrum of MDCT findings of the entities that compose acute aortic syndrome (AAS) - namely acute aortic dissection (AD), intramural hematoma (IMH) and penetrating atherosclerotic ulcer (PAU) - discussing their pathophysiology. These related entities have a similar nonspecific clinical presentation mimicking other conditions such as myocardial infarction. Therefore, a high degree of clinical suspicion should prompt immediate confirmation by non-invasive imaging techniques which can modify its natural history, being MDCT the technique of choice, allowing accurate detection, characterization and complications evaluation in the Emergency Department. METHODS: A detailed analysis of a series of clinical case of acute aortic syndrome seen at our Department is done, counselling with a review of the state of the art regarding the pathologic mechanisms, diagnostic evaluation and therapeutic management. RESULTS: They share a common feature of separation of the aortic walls. In AD there is an inward intimal displacement or tear, creating a true and a false lumen (double lumen). Detailing the extent, configuration - including true and false lumina distinction - and complications, are essential to proper treatment planning. IMH is defined by the presence of acute haemorrhage within wall layers without no visible intimal flap or tear on conventional techniques. It can lead to wall infarction and consequent dissection. PAU is due to erosion of internal elastic lamina - reaching the media - by an atherosclerotic plaque in the setting of advanced atherosclerosis or, less commonly, after rupture of a mycotic plaque or due to connective tissue disorders, appearing as an irregular focal contrasted outpouching outside the lumen. It can precipitate IMH or a pseudoaneurysm and progress, frequently, to dissection or rupture, coursing with high mortality, if not treated. Well known complications are aortic rupture with massive haemorrhage, pericardial tamponade by hemopericardium, mediastinal hematoma or hemothorax, pulmonary artery stenosis and/or pulmonary haemorrhage or organ ischemia. CONCLUSION: MDCT findings knowledge allows a correct diagnosis. These life-threatening entities have an undistinguishable clinical presentation but different physiopathology mechanisms - reflected in differing radiologic findings - prognosis and management.

Objetivos: O presente artigo pretende ilustrar e analisar o espectro de achados tomodensitométricos (TDM) das três entidades que compõe a síndrome aórtico agudo (SAA) ­ designadamente dissecção aórtica aguda (DA), hematoma intramural (HIM) e úlcera aterosclerótica penetrante (UAP) ­ e discutir a sua fisiopatologia. Estas entidades, estreitamente relacionadas, manifestam-se, habitualmente, de forma inespecífica, mimetizando outras condições clínicas, como o enfarte agudo do miocárdio (EAM). Assim sendo, um elevado grau de suspeição clínica impõe uma confirmação imediata por técnicas de imagem não invasivas que podem modificar a história natural da doença, sendo, num contexto emergente, o estudo dinâmico multidetectores por tomografia computorizada (TC), a técnica de eleição. Permite, com elevada acuidade diagnóstica, a deteção, caracterização e a avaliação de complicações. Métodos: É feita uma análise detalhada de uma série de casos clínicos de SAA observada no nosso Departamento, conciliando com a revisão do estado da arte no que diz respeito aos mecanismos patológicos, avaliação diagnóstica e opções terapêuticas. Resultados: As três entidades partilham de uma característica comum, a separação anómala das camadas da parede aórtica. Na DA observa-se uma descontinuidade focal com destacamento da íntima em direção ao lúmen, criando um duplo lúmen (verdadeiro e falso). Detalhar a extensão, morfologia ­ incluindo a distinção dos dois lumens ­ e caracterizar possíveis complicações, são aspetos essenciais à decisão e planeamento da terapêutica. O HIM é definido pela presença de uma hemorragia aguda ou recente na espessura da parede vascular, sem que seja possível objetivar uma descontinuidade da íntima, utilizando técnicas de imagem convencionais. Poderá progredir com enfarte parietal e, consequentemente, disseção. A UAP deve-se à erosão a lâmina elástica interna ­ com atingimento da média ­ geralmente, por uma placa aterosclerótica num contexto de aterosclerose avançada; ou, menos frequentemente, é consequência da rotura de uma placa micótica, ou de doenças do tecido conjuntivo; manifestando-se por uma irregularidade com protusão focal da parede, em continuidade com o lúmen. Pode precipitar um HIM ou progredir com a formação de um pseudoaneurisma e/ou disseção, ou mesmo rotura, de elevada mortalidade se não tratados. Constituem complicações a rotura aórtica com hemorragia massiva, tamponamento pericárdico por hemopericárdio, hemotórax ou hematoma mediastínico, estenose da artéria pulmonar e/ou hemorragia pulmonar, ou isquemia de órgãos. Conclusão: O reconhecimento dos achados TDM permite um diagnóstico atempado e correto. Estas entidades ­ potencialmente fatais ­ são, muitas vezes, indistinguíveis clinicamente, embora apresentem mecanismos fisiopatológicos distintos, o que se traduz em diferentes achados imagiológicos, prognósticos e abordagens terapêuticas.

RNA polymerase II kinetics in polo polyadenylation signal selection.

Regulated alternative polyadenylation is an important feature of gene expression, but how gene transcription rate affects this process remains to be investigated. polo is a cell-cycle gene that uses two poly(A) signals in the 3' untranslated region (UTR) to produce alternative messenger RNAs that differ in their 3'UTR length. Using a mutant Drosophila strain that has a lower transcriptional elongation rate, we show that transcription kinetics can determine alternative poly(A) site selection. The physiological consequences of incorrect polo poly(A) site choice are of vital importance; transgenic flies lacking the distal poly(A) signal cannot produce the longer transcript and die at the pupa stage due to a failure in the proliferation of the precursor cells of the abdomen, the histoblasts. This is due to the low translation efficiency of the shorter transcript produced by proximal poly(A) site usage. Our results show that correct polo poly(A) site selection functions to provide the correct levels of protein expression necessary for histoblast proliferation, and that the kinetics of RNA polymerase II have an important role in the mechanism of alternative polyadenylation.

Temperature-induced coexistence of a conducting bilayer and the bulk-terminated surface of the topological insulator Bi2Te3.

Topological insulators such as Bi2Se3 and Bi2Te3 have extremely promising transport properties, due to their unique electronic behavior: they are insulators in the bulk and conducting at the surface. Recently, the coexistence of two types of surface conducting channels has been observed for Bi2Se3, one being Dirac electrons from the topological state and the other electrons from a conventional two-dimensional gas. As an explanation for this effect, a possible structural modification of the surface of these materials has been hypothesized. Using scanning tunneling microscopy we have directly observed the coexistence of a conducting bilayer and the bare surface of bulk-terminated Bi2Te3. X-ray crystal truncation rod scattering was used to directly show the stabilization of this epitaxial bilayer which is primarily composed of bismuth. Using this information, we have performed density functional theory calculations to determine the electronic properties of the possible surface terminations. They can be used to understand recent angular resolved photoemission data which have revealed this dual surface electronic behavior.

Magnetic doping in transition metal dichalcogenides.

Transition metal dichalcogenides (TMDCs) are materials with unique electronic properties due to their two-dimensional nature. Recently, there is a large and growing interest in synthesizing ferromagnetic TMDCs for applications in electronic devices and spintronics. Apart from intrinsically magnetic examples, modification via either intrinsic defects or external dopants may induce ferromagnetism in non-magnetic TMDCs and, hence expand the application of these materials. Here, we review recent experimental work on intrinsically non-magnetic TMDCs that present ferromagnetism as a consequence of either intrinsic defects or doping via self-flux approach, ion implantation or e-beam evaporation. The experimental work discussed here is organized by modification/doping mechanism. We also review current work on density functional theory calculations that predict ferromagnetism in doped systems, which also serve as preliminary data for the choice of new doped TMDCs to be explored experimentally. Implementing a controlled process to induce magnetism in two-dimensional materials is key for technological development and this topical review discusses the fundamental procedures while presenting promising materials to be investigated in order to achieve this goal.

Evolution of chromosome-arm aberrations in breast cancer through genetic network rewiring.

The basal breast cancer subtype is enriched for triple-negative breast cancer (TNBC) and displays consistent large chromosomal deletions. Here, we characterize evolution and maintenance of chromosome 4p (chr4p) loss in basal breast cancer. Analysis of The Cancer Genome Atlas data shows recurrent deletion of chr4p in basal breast cancer. Phylogenetic analysis of a panel of 23 primary tumor/patient-derived xenograft basal breast cancers reveals early evolution of chr4p deletion. Mechanistically we show that chr4p loss is associated with enhanced proliferation. Gene function studies identify an unknown gene, C4orf19, within chr4p, which suppresses proliferation when overexpressed-a member of the PDCD10-GCKIII kinase module we name PGCKA1. Genome-wide pooled overexpression screens using a barcoded library of human open reading frames identify chromosomal regions, including chr4p, that suppress proliferation when overexpressed in a context-dependent manner, implicating network interactions. Together, these results shed light on the early emergence of complex aneuploid karyotypes involving chr4p and adaptive landscapes shaping breast cancer genomes.

LEAP: a novel LC3C-dependent pathway connects autophagy, endocytic trafficking and signaling.

Macroautophagy/autophagy acts to promote homeostasis and is increasingly understood to selectively target cargo for degradation. The LC3-family of proteins mediate diverse yet distinct cargo recruitment to phagophores. However, what underlies specificity for cargo engagement among LC3 proteins is poorly understood. Using an unbiased protein interaction screen of LC3B and LC3C, we uncover a novel LC3C-endocytic-associated-pathway (LEAP) that recruits selective plasma membrane (PM) cargo to phagophores. We show LC3C but not LC3B localizes to peripheral endosomes and engages proteins that traffic between the PM, endosomes and autophagosomes. We establish that endocytic LC3C binds cargo internalized from the PM, including MET receptor tyrosine kinase and TFRC (transferrin receptor), and targets them toward autophagic degradation. These findings identify LEAP as an unexpected LC3C-dependent pathway, providing new understanding of selective coupling of PM signaling and autophagic degradation with important implications in cancer and other disease states.

Assessment of Wild Rocket (Diplotaxis tenuifolia (L.) DC.) Germplasm Accessions by NGS Identified SSR and SNP Markers.

Rocket is the common designation for two baby-leaf salad crops of the Brassicaceae family: Eruca sativa (L.) Cav., usually referred to as annual garden rocket, and Diplotaxis tenuifolia (L.) DC. commonly named to as perennial wild rocket. E. sativa is used for human consumption since antiquity. However, the growing consumer preference for D. tenuifolia is being accompanied by the fast increase in its production area and commercialization of new cultivars. Nevertheless, the worldwide number of wild rocket accessions maintained in germplasm collections is very reduced, the solution for which situation the project "REMIRucula" intends to contribute, establishing a germplasm collection at the INIAV, Oeiras, Portugal. Herein, we report on the establishment via next generation sequencing (NGS) of the first genome assembly of D. tenuifolia and the identification of specific single sequence repeat (SSR) and single nucleotide polymorphisms (SNP) loci for the establishment of specific DNA-markers for this species. A representative set of 87 D. tenuifolia and 3 E. sativa accessions were assessed by 5 SSR and 9 SNP-CAPS markers, allowing a drastic discrimination between both species and the establishment of unequivocal molecular fingerprints for the analyzed accessions. The non-discrimination within six pairs and one trio of D. tenuifolia accessions is discussed.

B cell linker protein (BLNK) is a regulator of Met receptor signaling and trafficking in non-small cell lung cancer.

Met is an oncogene aberrantly activated in multiple cancers. Therefore, to better understand Met biology and its role in disease we applied the Mammalian Membrane Two-Hybrid (MaMTH) to generate a targeted interactome map of its interactions with human SH2/PTB-domain-containing proteins. We identified thirty interaction partners, including sixteen that were previously unreported. Non-small cell lung cancer (NSCLC)-focused functional characterization of a Met-interacting protein, BLNK, revealed that BLNK is a positive regulator of Met signaling, and modulates localization, including ligand-dependent trafficking of Met in NSCLC cell lines. Furthermore, the interaction between Met and GRB2 is increased in the presence of BLNK, and the constitutive interaction between BLNK and GRB2 is increased in the presence of active Met. Tumor phenotypical assays uncovered roles for BLNK in anchorage-independent growth and chemotaxis of NSCLC cell lines. Cumulatively, this study provides a Met-interactome and delineates a role for BLNK in regulating Met biology in NSCLC context.

Endosomal LC3C-pathway selectively targets plasma membrane cargo for autophagic degradation.

Autophagy selectively targets cargo for degradation, yet mechanistic understanding remains incomplete. The ATG8-family plays key roles in autophagic cargo recruitment. Here by mapping the proximal interactome of ATG8-paralogs, LC3B and LC3C, we uncover a LC3C-Endocytic-Associated-Pathway (LEAP) that selectively recruits plasma-membrane (PM) cargo to autophagosomes. We show that LC3C localizes to peripheral endosomes and engages proteins that traffic between PM, endosomes and autophagosomes, including the SNARE-VAMP3 and ATG9, a transmembrane protein essential for autophagy. We establish that endocytic LC3C binds cargo internalized from the PM, including the Met receptor tyrosine kinase and transferrin receptor, and is necessary for their recruitment into ATG9 vesicles targeted to sites of autophagosome initiation. Structure-function analysis identified that LC3C-endocytic localization and engagement with PM-cargo requires the extended carboxy-tail unique to LC3C, the TBK1 kinase, and TBK1-phosphosites on LC3C. These findings identify LEAP as an unexpected LC3C-dependent pathway, providing new understanding of selective coupling of PM signalling with autophagic degradation.

Surgical Description of Laparoscopic Ovum Pick-Up in Buffalo Calves.

The technique of laparoscopic oocyte aspiration has been increasingly used in animals; however, there are few records of its use in buffaloes. To describe this technique, six suckling Murrah buffaloes aged between 3 and 5 months were used. Three laparoscopic ovum pick-ups were performed in each animal, with intervals of 15 days between surgeries, completing a total of 18 procedures. The technique used three surgical ports with optics and a high-definition video camera. The introduction of the first portal and insufflation of the abdomen was performed through the open technique, with aspiration using a 20 G needle transabdominally and a vacuum pump calibrated at 50 mmHg. The mean complete surgical time from anesthesia to the removal of the animal from the litter was 49 ± 9.8 min. There were 27.8% cases of insufflation on the wrong side of the omentum. The oocyte recovery rate of 60.3% remained within the normal range. However, the rate of viable oocytes recovered was low, with only 40.8% of those recovered undergoing in vitro embryo production (IVEP). These data demonstrate that this simple, minimally invasive technique is an excellent reproductive tool for the genetic improvement of buffalo species.

Dual role of topoisomerase II in centromere resolution and aurora B activity.

Chromosome segregation requires sister chromatid resolution. Condensins are essential for this process since they organize an axial structure where topoisomerase II can work. How sister chromatid separation is coordinated with chromosome condensation and decatenation activity remains unknown. We combined four-dimensional (4D) microscopy, RNA interference (RNAi), and biochemical analyses to show that topoisomerase II plays an essential role in this process. Either depletion of topoisomerase II or exposure to specific anti-topoisomerase II inhibitors causes centromere nondisjunction, associated with syntelic chromosome attachments. However, cells degrade cohesins and timely exit mitosis after satisfying the spindle assembly checkpoint. Moreover, in topoisomerase II-depleted cells, Aurora B and INCENP fail to transfer to the central spindle in late mitosis and remain tightly associated with centromeres of nondisjoined sister chromatids. Also, in topoisomerase II-depleted cells, Aurora B shows significantly reduced kinase activity both in S2 and HeLa cells. Codepletion of BubR1 in S2 cells restores Aurora B kinase activity, and consequently, most syntelic attachments are released. Taken together, our results support that topoisomerase II ensures proper sister chromatid separation through a direct role in centromere resolution and prevents incorrect microtubule-kinetochore attachments by allowing proper activation of Aurora B kinase.

Effects of pollution on dormant-stage banks of cladocerans and rotifers in a large tropical reservoir.

Here, we describe the abundance and composition of the dormant-stage banks of cladocerans and rotifers at two locations in a tropical reservoir (Furnas Reservoir, Minas Gerais, Brazil) that are subject to different anthropogenic impacts. We hypothesized that at the site that received sewage, the density of resting eggs would be higher, but the species richness would be lower. Sediment samples were collected monthly at the two sampling stations. We counted the number of dormant stages and performed hatching experiments in the laboratory. Combining both sampling locations, we found a total of 26 species, 16 cladocerans, and 10 rotifers. Our hypothesis was partially corroborated, since the abundance and richness of dormant stages were significantly higher in the location subjected to wastewater release. Environmental pollution resulting from wastewater release and the cultivation of tilapia in cages is the most likely factor contributing to the higher values of egg density at this location. In contrast, the presence of aquatic macrophytes (a possible result of nutrient enrichment) at the same site may have contributed to the increase in species richness. Finally, our study indicates that the wastewater release in the reservoir can affect the production of dormant stages by cladocerans and rotifers.

LC3C mediates selective autophagy of the MET RTK, inhibiting cancer cell invasion.

Macroautophagy/autophagy is an evolutionarily conserved degradative process with a central role in maintaining cellular homeostasis under conditions of stress, and recent evidence suggests this may occur in part through direct modification of cell signaling. The MET/HGF receptor tyrosine kinase (RTK) signaling axis is an important mediator of cell motility and invasion in normal cell functions and in cancer. We discovered a role for autophagy in regulating ligand-activated MET signaling and cellular responses. When autophagy is induced by starvation, the HGF-activated and internalized MET RTK is selectively recruited for autophagic degradation through complex formation with the MAP1LC3C autophagy protein. Decreased LC3C expression in cancer results in loss of autophagic degradation of MET and enhanced HGF-stimulated cell invasion implicated in metastatic progression. This emerging role for autophagy in selectively regulating signaling proteins has implications for understanding cellular adaptations to stress and the functions of autophagy at different stages of cancer progression.

Molecular Beam Epitaxy of Transition Metal (Ti-, V-, and Cr-) Tellurides: From Monolayer Ditellurides to Multilayer Self-Intercalation Compounds.

Material growth by van der Waals epitaxy has the potential to isolate monolayer (ML) materials and synthesize ultrathin films not easily prepared by exfoliation or other growth methods. Here, the synthesis of the early transition metal (Ti, V, and Cr) tellurides by molecular beam epitaxy (MBE) in the mono- to few-layer regime is investigated. The layered ditellurides of these materials are known for their intriguing quantum- and layer dependent- properties. Here we show by a combination of in situ sample characterization and comparison with computational predictions that ML ditellurides with octahedral 1T structure are readily grown, but for multilayers, the transition metal dichalcogenide (TMDC) formation competes with self-intercalated compounds. CrTe2, a TMDC that is known to be metastable in bulk and easily decomposes into intercalation compounds, has been synthesized successfully in the ML regime at low growth temperatures. At elevated growth temperatures or for multilayers, only the intercalation compound, equivalent to a bulk Cr3Te4, could be obtained. ML VTe2 is more stable and can be synthesized at higher growth temperatures in the ML regime, but multilayers also convert to a bulk-equivalent V3Te4 compound. TiTe2 is the most stable of the TMDCs studied; nevertheless, a detailed analysis of multilayers also indicates the presence of intercalated metals. Computation suggests that the intercalation-induced distortion of the TMDC-layers is much reduced in Ti-telluride compared to V-, and Cr-telluride. This makes the identification of intercalated materials by scanning tunneling microscopy more challenging for Ti-telluride. The identification of self-intercalation compounds in MBE grown multilayer chalcogenides may explain observed lattice distortions in previously reported MBE grown early transition metal chalcogenides. On the other hand, these intercalation compounds in their ultrathin limit can be considered van der Waals materials in their own right. This class of materials is only accessible by direct growth methods but may be used as "building blocks" in MBE-grown van der Waals heterostructures. Controlling their growth is an important step for understanding and studying the properties of these materials.

Monolayer Modification of VTe2 and Its Charge Density Wave.

Interlayer interactions in layered transition metal dichalcogenides are known to be important for describing their electronic properties. Here, we demonstrate that the absence of interlayer coupling in monolayer VTe2 also causes their structural modification from a distorted 1T' structure in bulk and multilayer samples to a hexagonal 1T structure in the monolayer. X-ray photoemission spectroscopy indicates that this structural transition is associated with electron transfer from the vanadium d bands to the tellurium atoms for the monolayer. This charge transfer may reduce the in-plane d orbital hybridization and thus favor the undistorted 1T structure. Phonon-dispersion calculations show that, in contrast to the 1T' structure, the 1T structure exhibits imaginary phonon modes that lead to a charge density wave (CDW) instability, which is also observed by low-temperature scanning tunneling microscopy as a 4 × 4 periodic lattice distortion. Thus, this work demonstrates a novel CDW material, whose properties are tuned by interlayer interactions.

HGF-induced migration depends on the PI(3,4,5)P3-binding microexon-spliced variant of the Arf6 exchange factor cytohesin-1.

Differential inclusion or skipping of microexons is an increasingly recognized class of alternative splicing events. However, the functional significance of microexons and their contribution to signaling diversity is poorly understood. The Met receptor tyrosine kinase (RTK) modulates invasive growth and migration in development and cancer. Here, we show that microexon switching in the Arf6 guanine nucleotide exchange factor cytohesin-1 controls Met-dependent cell migration. Cytohesin-1 isoforms, differing by the inclusion of an evolutionarily conserved three-nucleotide microexon in the pleckstrin homology domain, display differential affinity for PI(4,5)P2 (triglycine) and PI(3,4,5)P3 (diglycine). We show that selective phosphoinositide recognition by cytohesin-1 isoforms promotes distinct subcellular localizations, whereby the triglycine isoform localizes to the plasma membrane and the diglycine to the leading edge. These data highlight microexon skipping as a mechanism to spatially restrict signaling and provide a mechanistic link between RTK-initiated phosphoinositide microdomains and Arf6 during signal transduction and cancer cell migration.

LC3C-Mediated Autophagy Selectively Regulates the Met RTK and HGF-Stimulated Migration and Invasion.

The Met/hepatocyte growth factor (HGF) receptor tyrosine kinase (RTK) is deregulated in many cancers and is a recognized target for cancer therapies. Following HGF stimulation, the signaling output of Met is tightly controlled by receptor internalization and sorting for degradation or recycling. Here, we uncover a role for autophagy in selective degradation of Met and regulation of Met-dependent cell migration and invasion. Met engagement with the autophagic pathway is dependent on complex formation with the mammalian ATG8 family member MAP1LC3C. LC3C deletion abrogates Met entry into the autophagy-dependent degradative pathway, allowing identification of LC3C domains required for rescue. Cancer cells with low LC3C levels show enhanced Met stability, signaling, and cell invasion. These findings provide mechanistic insight into RTK recruitment to autophagosomes and establish distinct roles for ATG8 proteins in this process, supporting that differential expression of ATG8 proteins can shape the functional consequences of autophagy in cancer development and progression.

The condensin I subunit Barren/CAP-H is essential for the structural integrity of centromeric heterochromatin during mitosis.

During cell division, chromatin undergoes structural changes essential to ensure faithful segregation of the genome. Condensins, abundant components of mitotic chromosomes, are known to form two different complexes, condensins I and II. To further examine the role of condensin I in chromosome structure and in particular in centromere organization, we depleted from S2 cells the Drosophila CAP-H homologue Barren, a subunit exclusively associated with condensin I. In the absence of Barren/CAP-H the condensin core subunits DmSMC4/2 still associate with chromatin, while the other condensin I non-structural maintenance of chromosomes family proteins do not. Immunofluorescence and in vivo analysis of Barren/CAP-H-depleted cells showed that mitotic chromosomes are able to condense but fail to resolve sister chromatids. Additionally, Barren/CAP-H-depleted cells show chromosome congression defects that do not appear to be due to abnormal kinetochore-microtubule interaction. Instead, the centromeric and pericentromeric heterochromatin of Barren/CAP-H-depleted chromosomes shows structural problems. After bipolar attachment, the centromeric heterochromatin organized in the absence of Barren/CAP-H cannot withstand the forces exerted by the mitotic spindle and undergoes irreversible distortion. Taken together, our data suggest that the condensin I complex is required not only to promote sister chromatid resolution but also to maintain the structural integrity of centromeric heterochromatin during mitosis.