29 research outputs found
Novel insights into filopodia function – A focus on integrin and F-actin regulation
Get PDFFilopodia are actin-rich cell protrusions that are extended from the plasma membrane by different cell types in order to sense the surrounding environment. In cancer cells, the emergence of filopodia supports metastasis, while in neuronal cells filopodia help to form synapses by probing adjacent cells for suitable presynaptic partners. Filopodia can make contact with the extracellular matrix with small, integrinmediated adhesions located at their tips. During cancer invasion, recognition of the extracellular matrix by filopodia not only supplies migrating cells with guidance cues but has also been linked with increased colony growth at the metastatic site. In neuronal cells, inhibition of integrin activity has been shown to negatively impact synapse formation. Although both filopodia and integrin-positive adhesions have roles in metastasis or in synaptogenesis, filopodial adhesions remain under-studied cellular structures and there exists minimal literature on how these adhesions are regulated or how they function. The objective of this study was to reveal novel regulatory mechanisms of filopodia by studying two integrin and filopodia linked proteins: myosin-X and SHANK3. The work presented here provides fundamental information on how 1) integrins are activated at filopodia tips, 2) which integrinlinked proteins are recruited to adhesions at filopodia providing a road-map to classify these adhesions and 3) how SHANK3, an F-actin network organizer and filopodia regulator, modulates the crosstalk between integrin and F-actin via direct and conformationally regulated binding with F-actin. The thesis also provides novel methodology in the form of a high-end biochemical binding assay (4) where protein binding to integrin tails can be interrogated in the presence of a lipidic membrane.Solun filopodien toiminta
Filopodit ovat solukalvon pullistumia, joita täyttää sisältäpäin solun aktiinitukiranka. Filopodit syntyvät solukalvon pullistuessa ulospäin aktiinitukirangan vaikutuksesta ja solut käyttävät niitä ympäristönsä aistimiseen käyttämällä filopodien kärjissä sijaitsevia tarttumisreseptoreja - integriinejä. Syövän leviämisen aikana solujen kyky tunnistella ympäröivää soluväliainetta tarjoaa solulle tarkkaa tietoa sen ympäristöstä, ohjaten solun kulkua vaikeassa 3-ulotteisessa soluväliaineen verkostossa. Toisaalta hermosolut käyttävät filopodeja naapurisolujensa (tai ympäröivän kudoksen) tarkasteluun hermoliitosten muodostusprosessissa. Vaikka filopodit ja integriinireseptorit ohjaavat sekä syövän leviämistä ja aivojen normaalia toimintaa, filopodien välittämien integriini-positiivisten soluadheesioiden synty tunnetaan huonosti. Lisäksi filopodien soluadheesioiden säätely sekä vaikutukset solun toiminnalle ovat heikosti ymmärrettyjä tapahtumasarjoja. Tämän väitöskirjatyön tarkoituksena oli ymmärtää filopodien solullisia säätelyketjuja paremmin tutkimalla kahta integriineihin ja filopodeihin aiemmin liitettyä proteiinia: myosiini-X ja SHANK3. Tässä väitöskirjatyössä esitetyt tulokset tuovat täysin uutta tietoa seuraavista tapahtumista: 1) miten filopodit muodostavat adheesioita soluväliaineen kanssa 2) mitkä solun adheesioproteiinit sijoittuvat filopodien kärkiin adheesiomuodostusprosessin aikana sekä 3) kuinka SHANK3 proteiini säätelee samanaikaisesti solun aktiinitukirankaa ja integriiniaktiivisuutta. Lisäksi väitöskirja sisältää menetelmällisen julkaisun uudesta biokemiallisesta koeasetelmasta, jonka avulla voidaan paremmin tutkia solun proteiinien sitoutumista integriinireseptoreihin solukalvon läheisyydessä.ei tietoa saavutettavuudest
Myosin-X: A molecular motor driving cancer cell invasion
No full textIn metastasis migratory cancer cells invade through stroma and spread throughout the body forming metastatic colonies into distant organs.
Myosin-X is a member of the vast myosin superfamily of actin dependent motor proteins. Functionally very different from myosin-II, myosin-X works by transporting intracellular cargo along actin filaments. Myosin-X is able to induce filopodia formation and can support their function by transporting cargo towards filopodia tips. Among the myosin-X cargo are the integrin family of transmembrane receptors that have been for long known to be crucial for cell motility. Whereas integrins have roots in many aspects of migratory processes, myosin-X expression has been shown to worsen patient prognosis and increase metastatic potential. By using standard and novel cytometric techniques, state-of-the-art microscopy techniques and biochemical tools this Pro gradu thesis addresses how myosin-X (MYO10) supports filopodia-linked cancer cell invasion that is detected in single and collective cell migration.
Myosin-X expression was found to inhibit 51 integrin activation via its FERM domain in triple-negative breast carcinoma and osteosarcoma cell lines. In addition, myosin-X expression was seemed to support integrin trafficking in a p53 mutant cell line but not in p53 wild-types cells. Upon PH domain disruption, myosin-X was found to localize to subcellular compartments and to the cell periphery together with 1 integrin. In this case myosin-X was unable to inactivate 1 integrin, perhaps due to loss of a direct interaction. However, PH domain deficient myosin-X lowers total 1 integrin levels at the plasma membrane. In total, data from experiments on myosin-X with disrupted or missing PH domain suggest a common route of trafficking for these proteins. Structural bioinformatics, proximity ligation assay and a novel proteoliposomal binding assay were used to further assess the interaction between myosin-X and integrin. In the process, a previously unnoticed RA-like subdomain was discovered to be situated inside myosin-X FERM domain.Siirretty Doriast
Matematiikka ja tilastolliset mallit syövän hoitovasteen ennustamisessa
No full textSyöpäpotilaiden hoitovasteissa on usein yksilöllisiä eroja. Yksilölliset vaihtelut voivat johtaa vaikeisiin haittaoireisiin ilman havaittavaa syövän hoitovastetta, ja siksi potilaskohtaista lääkevastetta on oleellista pyrkiä ennustamaan potilaan syöpäkasvaimen biologisten ominaispiirteiden perusteella. Matemaattiset ja tilastolliset mallit tarjoavat monipuolisen valikoiman laskennallisia työkaluja, joiden ennusteellinen käyttö syöpädiagnostiikan rinnalla ja osana syövän hoitopolkua on keskeinen osa tulevaisuuden yksilöllistettyä lääketiedettä. Parhaimmillaan hoitovasteen ennustaminen vähentää turhia lääkehaittoja, auttaa potilaskohtaisesti ihanteellisen hoidon valinnassa ja vähentää kalliiden hoitokeinojen käyttöä tapauksissa, joissa potilas ei niistä merkittävästi hyödy. Vaikka kasvaimen ja potilaan yksilölliseen biologiaan pohjautuvia hoitovaste-ennusteita käytetään vielä verrattain vähän kliinisessä päätöksenteossa, tilanne todennäköisesti muuttuu seuraavien vuosien aikana.Peer reviewe
Business students’ learning and assessment in a COVID-19 world: empirical evidence from Finland
No full textPublisher Copyright: © 2023 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.This study examines business students’ learning and assessment under remote teachings during the COVID-19 pandemic in a well-established Finnish university. A survey method is used to collect information on 336 business students including 42 accounting students. As indicated by students’ responses, a majority of the students succeeded in assessing and self-regulating their learning, but a considerable group of students failed in this task. Students gave a lot of positive feedback on supervised electronic exams, such as scheduling efficiency, improved ability to focus, and reduced stress level. Students also reported a low number of monitoring problems in these exams. Furthermore, the results provide evidence that some students see the risk that problems in monitoring coursework threaten the value of their university degrees. However, about half of the students did not want to increase monitoring. Accounting students’ opinions were mostly similar to those of the other business students. This study contributes to the literature by showing key factors that influence students’ learning in remote teaching under abnormal conditions. In addition, it demonstrates how the constructivist model of learning can be used to explain students’ learning and assessment in these circumstances.Peer reviewe
RepurposeDrugs : an interactive web-portal and predictive platform for repurposing mono- and combination therapies
No full textRepurposeDrugs (https://repurposedrugs.org/) is a comprehensive web-portal that combines a unique drug indication database with a machine learning (ML) predictor to discover new drug-indication associations for approved as well as investigational mono and combination therapies. The platform provides detailed information on treatment status, disease indications and clinical trials across 25 indication categories, including neoplasms and cardiovascular conditions. The current version comprises 4314 compounds (approved, terminated or investigational) and 161 drug combinations linked to 1756 indications/conditions, totaling 28 148 drug–disease pairs. By leveraging data on both approved and failed indications, RepurposeDrugs provides ML-based predictions for the approval potential of new drug–disease indications, both for mono- and combinatorial therapies, demonstrating high predictive accuracy in cross-validation. The validity of the ML predictor is validated through a number of real-world case studies, demonstrating its predictive power to accurately identify repurposing candidates with a high likelihood of future approval. To our knowledge, RepurposeDrugs web-portal is the first integrative database and ML-based predictor for interactive exploration and prediction of both single-drug and combination approval likelihood across indications. Given its broad coverage of indication areas and therapeutic options, we expect it accelerates many future drug repurposing projects.Peer reviewe
Filopodome Mapping Identifies p130Cas as a Mechanosensitive Regulator of Filopodia Stability
Get PDFin filopodia tips, predicts critical roles for PIs in regulating filopodia ultra-structure and function. Our mapping further reveals that filopodia adhesions consist of a unique set of proteins, the filopodome, that are distinct from classical nascent adhesions, focal adhesions, and fibrillar adhesions. Using live imaging, we observe that filopodia adhesions can give rise to nascent adhesions, which, in turn, form focal adhesions. We demonstrate that p130Cas (BCAR1) is recruited to filopodia tips via its C-terminal Cas family homology domain (CCHD) and acts as a mechanosensitive regulator of filopodia stability. Finally, we demonstrate that our map based on myosin-X-induced filopodia can be translated to endogenous filopodia and fascin- and IRSp53-mediated filopodia
ScType enables fast and accurate cell type identification from spatial transcriptomics data
No full textThe limited resolution of spatial transcriptomics (ST) assays in the past has led to the development of cell type annotation methods that separate the convolved signal based on available external atlas data. In light of the rapidly increasing resolution of the ST assay technologies, we made available and investigated the performance of a deconvolution-free marker-based cell annotation method called scType. In contrast to existing methods, the spatial application of scType does not require computationally strenuous deconvolution, nor large single-cell reference atlases. We show that scType enables ultra-fast and accurate identification of abundant cell types from ST data, especially when a large enough panel of genes is detected. Examples of such assays are Visium and Slide-seq, which currently offer the best trade-off between high resolution and number of genes detected by the assay for cell type annotation.Peer reviewe
Myosin-X recruits lamellipodin to filopodia tips
No full textMyosin-X (MYO10), a molecular motor localizing to filopodia, is thought to transport various cargo to filopodia tips, modulating filopodia function. Yet, only a few MYO10 cargoes have been described. Here, using GFP-Trap and BioID approaches combined with mass spectrometry, we identified lamellipodin (RAPH1) as a novel MYO10 cargo. We report that the FERM domain of MYO10 is required for RAPH1 localization and accumulation at filopodia tips. Previous studies have mapped RAPH1 interaction with adhesome components to its talinbinding and Ras-association domains. Surprisingly, we find that the RAPH1 MYO10-binding site is not within these domains. Instead, it comprises an area with previously unknown functions. Functionally, RAPH1 supports MYO10 filopodia formation and stability but is not involved in regulating integrin activity in filopodia tips. Taken together, our data indicate a feed-forward mechanism whereby MYO10 filopodia are positively regulated by MYO10-mediated transport of RAPH1 to the filopodium tip
Superresolution architecture of cornerstone focal adhesions in human pluripotent stem cells
Get PDFWhile it is clear that key transcriptional programmes are important for maintaining pluripotency, the requirement for cell adhesion to the extracellular matrix remains poorly defined. Human pluripotent stem cells (hPSCs) form colonies encircled by an actin ring and large stable cornerstone focal adhesions (FA). Using superresolution two-colour interferometric photo-activated localisation microscopy, we examine the three-dimensional architecture of cornerstone adhesions and report vertical lamination of FA proteins with three main structural features distinct from previously studied focal adhesions: 1) integrin β5 and talin are present at high density, at the edges of cornerstone FA, adjacent to a vertical kank-rich protein wall, 2) vinculin localises higher than previously reported, displaying a head-above-tail orientation, and 3) surprisingly, actin and α-actinin are present in two discrete z-layers. Finally, we report that depletion of kanks diminishes FA patterning, and actin organisation within the colony, indicating a role for kanks in hPSC colony architecture.</p
