The cytoplasmic tail of the mechanosensitive channel Pkd2 regulates its internalization and clustering in eisosomes.

Polycystins are a family of conserved ion channels, mutations of which lead to one of the most common human genetic disorders, namely, autosomal dominant polycystic kidney disease. Schizosacchromyces pombe possesses an essential polycystin homologue, Pkd2, which directs Ca2+ influx on the cell surface in response to membrane tension, but its structure remains unsolved. Here, we analyzed the structure-function relationship of Pkd2 based on its AlphaFold-predicted structure. Pkd2 consists of three domains, the extracellular lipid-binding domain (LBD), nine-helix transmembrane domain (TMD) and C-terminal cytoplasmic domain (CCD). Our genetic and microscopy data revealed that LBD and TMD are essential for targeting Pkd2 to the plasma membrane from the endoplasmic reticulum. In comparison, CCD ensures the polarized distribution of Pkd2 by promoting its internalization and preventing its clustering in the eisosome, a caveolae-like membrane compartment. The domains of Pkd2 and their functions are conserved in other fission yeast species. We conclude that both extracellular and cytoplasmic domains of Pkd2 are crucial for its intracellular trafficking and function. We propose that mechanosensitive channels can be desensitized through either internalization or clustering in low-tension membrane compartments.

Participatory Action Research Among People With Serious Mental Illness: A Scoping Review.

Participatory action research (PAR) is a research approach that creates spaces for marginalized individuals and communities to be co-researchers to guide relevant social change. While working toward social transformation, all members of the PAR team often experience personal transformation. Engaging people with serious mental illness (PSMI) in PAR helps them to develop skills and build relationships with stakeholders in their communities. It supports positive changes that persist after the completion of the formal research project. With the increasing recognition of PAR's value in PSMI, it is helpful to consider the challenges and advantages of this approach to research with this population. This review aimed at determining how PAR has been conducted with PSMI and at summarizing strategies used to empower PSMI as co-researchers by engaging them in research. This scoping review followed five steps Arkesy and O'Malley (2005) outlined. We charted, collated, and summarized relevant information from 87 studies that met the inclusion criteria. We identified five strategies to empower PSMI through PAR. These are to build capacity, balance power distribution, create collaborative environments, promote peer support, and enhance their engagement as co-researchers. In conclusion, PAR is an efficient research approach to engage PSMI. Further, PSMI who engage in PAR may benefit from strategies for empowerment that meet their unique needs as co-researchers.

The prevalence of adult de novo scoliosis: A systematic review and meta-analysis.

INTRODUCTION: Primary degenerative scoliosis represents a new scoliosis developing in patients with no prior history of spinal curvature. Researchers sought to determine the prevalence of this type of scoliosis. METHODS: MEDLINE, Embase, CINAHL, Web of Science and PubMed were searched from inception to 28th March, 2018. Studies that assessed adults from the general population for scoliosis using imaging techniques were included. Studies were included only if the study authors had excluded participants with previously diagnosed scoliosis and/or spinal disorders. Mixed-effects logistic-regression was used to establish an overall prevalence estimate with 95% confidence intervals (primary outcome) and to examine the effect of age and sex (secondary outcomes). RESULTS: Four cross-sectional studies and one cohort study, involving 4069 participants (66.6% Female), aged between 41 and 94 years, were eligible for inclusion. Reported prevalence figures ranged from 13 to 68%. The pooled prevalence estimate from the mixed-effects logistic regression analysis was 37.6% (95% CI 18.7-61.8). Females were more likely to suffer from scoliosis compared with males (p < 0.001), with prevalence figures of 41.2% (95% CI 20.7-65.8) versus 27.5% (95% CI 12.2-51.1), respectively. Individuals aged < 60 years had a prevalence of 13% (95% CI 5.2-30.2), whereas the prevalence estimates were substantially higher in the > 60 age group [36% (95% CI 17.4-60.6)]. CONCLUSION: Primary degenerative scoliosis is a highly prevalent condition, especially in females. Further research targeting this type of scoliosis is required to obtain more precise global prevalence estimates and to understand the influence of age and sex.

Prevention of Unintentional Childhood Injury.

Unintentional injury accounts for one-third of deaths in children and adolescents each year, primarily from motor vehicle crashes. Children younger than 13 years should be restrained in the back seat, and infants and toddlers should remain rear-facing until at least two years of age. Infants should be positioned on their backs in a crib, on a mattress with only a fitted sheet to avoid suffocation, and all items that could potentially entrap or entangle the child should be removed from the sleep environment. Fencing that isolates swimming pools from the house is effective in preventing drownings. Swimming lessons are recommended for all children by four years of age. Inducing vomiting after toxic ingestions is not recommended. Installing and maintaining smoke detectors, having a home escape plan, and teaching children how to respond during a fire are effective strategies for preventing fire-related injuries or death. The most effective way to prevent gun-related injuries in children and adolescents is the absence of guns from homes and communities. Family physicians should counsel patients with guns in the home to keep them locked, unloaded, and with ammunition stored in a separate locked location. Fall injuries can be reduced by avoiding walkers for infants and toddlers. Consistent helmet use while bicycling reduces head and brain injuries. Although direct counseling by physicians seems to improve some parental safety behaviors, its effect on reducing childhood injuries is unclear. Community-based interventions can be effective in high-risk populations.

Route previewing results in altered gaze behaviour, increased self-confidence and improved stepping safety in both young and older adults during adaptive locomotion.

Older adults with falls risk tend to look away prematurely from targets for safe foot placement to view future hazards; behaviour associated with increased anxiety and stepping inaccuracies. We aimed to determine the effectiveness of route previewing in reducing anxiety and optimizing gaze behaviour and stepping performance of younger and older adults. Nine younger and nine older adults completed six walks with three task complexities over two sessions. Each trial used either an isolated stepping target, or a target followed by either one or two obstacles. Participants with eyes closed, on hearing a signal, opened their eyes and initiated walking (go trials) or stood previewing the route for 10 s before starting (preview trials). Kinematic data were collected using a Vicon motion analysis system. Gaze behaviour was recorded using a Dikablis eye tracker. On average, both older and younger adults fixated the target for significantly longer during walking when they had previewed the route than when they had not. Self-confidence scores were also significantly higher following 'preview trials' than 'go trials'. Stepping performance significantly improved following route previewing (reduced Medial lateral foot placement variability for both groups and reduced anterior/posterior foot placement error in older adults only). These findings implicate route previewing as a potential intervention to increase self-confidence and reduce the risk of tripping in older adults.

A critical interpretive synthesis: Use of the occupational justice framework in research.

BACKGROUND: The occupational justice framework was established in the late 1990s with an agenda to spur occupational therapists to take action against injustices pertaining to occupation. METHODS: A critical interpretive synthesis of 23 texts was undertaken to examine how the occupational justice framework has been utilised in research, with a particular focus on how such research is located on a knowledge to action continuum and the extent to which it enacts the call to remediate occupational injustices. RESULTS: Within the texts reviewed, the occupational justice framework was predominantly used to interpret research findings, and only four studies explicitly used an action research approach. There was also a dominant tendency to individualise situations of occupational justice, but with some examples attending to the social and political production of injustices. Absences and silences related to the locations of the research in developed regions and a focus on conceptualisations of justice commensurate with a Western worldview were evident. CONCLUSIONS: Full realisation of the potential contributions of the occupational justice framework requires challenging traditional modes of research that focus primarily on knowledge generation, and expanding into modes of research that embrace a knowledge to action continuum. This expansion, which will enable occupational justice research to more fully embrace action-oriented work, requires practicing epistemological reflexivity, adopting a critical stance, incorporating a participatory action research approach and collaborating with scholars from different disciplines.

Ganglioside and Non-ganglioside Mediated Host Responses to the Mouse Polyomavirus.

Gangliosides serve as receptors for internalization and infection by members of the polyomavirus family. Specificity is determined by recognition of carbohydrate moieties on the ganglioside by the major viral capsid protein VP1. For the mouse polyomavirus (MuPyV), gangliosides with terminal sialic acids in specific linkages are essential. Although many biochemical and cell culture experiments have implicated gangliosides as MuPyV receptions, the role of gangliosides in the MuPyV-infected mouse has not been investigated. Here we report results of studies using ganglioside-deficient mice and derived cell lines. Knockout mice lacking complex gangliosides were completely resistant to the cytolytic and pathogenic effects of the virus. Embryo fibroblasts from these mice were likewise resistant to infection, and supplementation with specific gangliosides restored infectibility. Although lacking receptors for viral infection, cells from ganglioside-deficient mice retained the ability to respond to the virus. Ganglioside-deficient fibroblasts responded rapidly to virus exposure with a transient induction of c-fos as an early manifestation of a mitogenic response. Additionally, splenocytes from ganglioside-deficient mice responded to MuPyV by secretion of IL-12, previously recognized as a key mediator of the innate immune response. Thus, while gangliosides are essential for infection in the animal, gangliosides are not required for mitogenic responses and innate immune responses to the virus.

Norovirus outbreaks in german refugee camps in 2015.

Purpose Refugees often live in confined housing conditions with shared kitchen and sanitary facilities, rendering susceptible to communicable diseases. We here describe the outbreak, spread and self-limiting nature of a norovirus outbreak in a German refugee camp in the winter of 2015. Methods During a norovirus outbreak, data on clinical symptoms, nationality and living conditions was obtained in a refugee camp in northern Germany in the winter of 2015. Furthermore secondary data on norovirus outbreaks in 2015 was assessed. Results Amongst n = 982 refugees, n = 36 patients (3.7 %) presented with acute norovirus gastroenteritis. The vast majority of cases were children, only the first patient was admitted to the hospital. Intensified hygiene measures were implemented on day 2 of the outbreak, but new cases peaked on day 21 and occurred until one month after the first case. Different cultural backgrounds, eating habits and hygiene standards amongst the refugees made it particularly challenging to implement stringent isolation and hygiene measures. Despite these predisposing factors, only minor norovirus outbreaks were reported in refugee camps in 2015. Conclusion Adults refugees had a low attack rate of symptomatic norovirus infection, while small children are at high risk. Infection spreads despite hygiene measures and camp sites and staff should be prepared for the particular challenges of such situations with a particular focus on cultural-background specific implementation of hygiene measures.

Measles, mumps, rubella, and varicella seroprevalence in refugees in Germany in 2015.

PURPOSE: The current extent of migration poses emerging socio-economic and humanitarian challenges. Little is known on vaccination rates in migrants entering Europe, and the implementation of guidelines for serological testing and vaccination of refugees are pending. METHODS: We conducted seroprevalence analyses for measles, mumps, rubella and varicella (MMRV) in 678 refugees coming to Germany during the current crisis. RESULTS: The mean age of refugees was 28.8±11.4 years, and 76.1 % of subjects were male. Overall, IgG seronegativity was 7.4 % (95 % CI 5.5-9.6) for measles, 10.2 % (95 % CI 8.0-12.5) for mumps, 2.2 % (95 % CI 1.2-3.4) for rubella, and 3.3 % (95 % CI 1.9-4.9) for varicella. Seropositivity rates were age-dependent with considerably low values in children. For example, overall MMR immunity was 90.9 % (95 % CI 88.8-93.1), but only 73.1 % of minor aged refugees displayed complete seroprevalence against all three diseases, and only 68.9 % of children and adolescents were completely MMRV immune. CONCLUSION: Our initial data set suggests overall satisfactory MMRV immunity in adult migrants coming to Europe, but the observed low MMRV seroprevalences in refugee children support thorough and prompt vaccination of young migrants entering Europe. Taken together, our data set underlines the urgent need to implement and validate vaccination guidelines for refugee care in the current crisis.

Subependymal giant cell astrocytoma: current concepts, management, and future directions.

BACKGROUND: Subependymal giant cell astrocytoma (SEGA) is the most common central nervous system tumor in patients with tuberous sclerosis complex (TSC). SEGAs are generally benign, non-infiltrative lesions, but they can lead to intracranial hypertension, obstructive hydrocephalus, focal neurologic deficits, and even sudden death. DISCUSSION: Surgical resection has been the standard treatment for SEGAs, and it is generally curative with complete resection. However, not all SEGAs are amenable to safe and complete resection. Gamma Knife stereotactic radiosurgery provides another treatment option as a primary or adjuvant treatment for SEGAs, but it has highly variable response effects with sporadic cases demonstrating its efficacy. Recently, biologically targeted pharmacotherapy with mammalian target of rapamycin (mTOR) inhibitors such as sirolimus and everolimus has provided a safe and efficacious treatment option for patients with SEGAs. However, SEGAs can recur few months after drug discontinuation, indicating that mTOR inhibitors may need to be continued to avoid recurrence. Further studies are needed to evaluate the advantages and adverse effects of long-term treatment with mTOR inhibitors. This review presents an overview of the current knowledge and particularly highlights the surgical and medical options of SEGAs in patients with TSC.

Retrospective, Observational Analysis on the Impact of SARS-CoV-2 Variant Omicron in Hospitalized Immunocompromised Patients in a German Hospital Network-The VISAGE Study.

AIMS: Endemic SARS-CoV-2 infections still burden the healthcare system and represent a considerable threat to vulnerable patient cohorts, in particular immunocompromised (IC) patients. This study aimed to analyze the in-hospital outcome of IC patients with severe SARS-CoV-2 infection in Germany. METHODS: This retrospective, observational study, analyzed administrative data from inpatient cases (n = 146,324) in 84 German Helios hospitals between 1 January 2022 and 31 December 2022 with regard to in-hospital outcome and health care burden in IC patients during the first 12 months of Omicron dominance. As the primary objective, in-hospital outcomes of patients with COVID-19-related severe acute respiratory infection (SARI) were analyzed by comparing patients with (n = 2037) and without IC diagnoses (n = 14,772). Secondary analyses were conducted on IC patients with (n = 2037) and without COVID-19-related SARI (n = 129,515). A severe in-hospital outcome as a composite endpoint was defined per the WHO definition if one of the following criteria were met: intensive care unit (ICU) treatment, mechanical ventilation (MV), or in-hospital death. RESULTS: In total, 12% of COVID-related SARI cases were IC patients, accounting for 15% of ICU admissions, 15% of MV use, and 16% of deaths, resulting in a higher prevalence of severe in-hospital courses in IC patients developing COVID-19-related SARI compared to non-IC patients (Odds Ratio, OR = 1.4, p < 0.001), based on higher in-hospital mortality (OR = 1.4, p < 0.001), increased need for ICU treatment (OR = 1.3, p < 0.001) and mechanical ventilation (OR = 1.2, p < 0.001). Among IC patients, COVID-19-related SARI profoundly increased the risk for severe courses (OR = 4.0, p < 0.001). CONCLUSIONS: Our findings highlight the vulnerability of IC patients to severe COVID-19. The persistently high prevalence of severe outcomes in these patients in the Omicron era emphasizes the necessity for continuous in-hospital risk assessment and monitoring of IC patients.

Polymorphisms in toll-like receptor 4 underlie susceptibility to tumor induction by the mouse polyomavirus.

PERA/Ei (PE) mice are susceptible to tumor induction by polyomavirus (Py), while C57BR/cdJ (BR) mice are resistant. Antigen-presenting cells from BR mice respond to the virus with interleukin-12 (IL-12) and those from PE mice with IL-10. These polarized cytokine responses underlie the development of effective antitumor immunity in BR mice and the lack thereof in PE mice. An ex vivo cytokine production assay using spleen cells from infected [PE × BR] F2 mice together with a genome-wide SNP (single-nucleotide polymorphism)-based QTL (quantitative trait locus) analysis was used to map the determinant of cytokine production to a region of chromosome 4 carrying the Toll-like receptor 4 (TLR4) gene. Genotyping of infected F2 mice showed concordance of TLR4 allele-specific DNA sequences with the cytokine profile. Cytokine responses elicited by Py are MyD88 dependent. Bacterial lipopolysaccharide (LPS), a known TLR4 ligand, induced the same polarized responses as the virus in these host strains. Spleen cells from C3H/HeJ and C57BL/10ScNJ LPS-nonresponsive mice challenged in vitro with Py showed an impaired IL-12 response but were unaffected in IL-10 production. TLR4s of strains PE and BR differ by 3 amino acid substitutions, 2 in the extracellular domain and 1 in the intracellular domain. cDNAs encoding the TLR4s signaled equally to an NF-κB reporter in 293 cells in a ligand-independent manner. When introduced into TLR2/TLR4 double-knockout macrophages, the TLR4 cDNA from BR mice conferred a robust IL-12 response to Py and no IL-10 response. The TLR4 cDNA from PE mice failed to confer a response with either cytokine. These results establish TLR4 as a key mediator of the cytokine response governing susceptibility to tumor induction by Py.

The structural basis of the talin-KANK1 interaction that coordinates the actin and microtubule cytoskeletons at focal adhesions.

Adhesion between cells and the extracellular matrix is mediated by heterodimeric (αß) integrin receptors that are intracellularly linked to the contractile actomyosin machinery. One of the proteins that control this link is talin, which organizes cytosolic signalling proteins into discrete complexes on ß-integrin tails referred to as focal adhesions (FAs). The adapter protein KANK1 binds to talin in the region of FAs known as the adhesion belt. Here, we adapted a non-covalent crystallographic chaperone to resolve the talin-KANK1 complex. This structure revealed that the talin binding KN region of KANK1 contains a novel motif where a ß-hairpin stabilizes the α-helical region, explaining both its specific interaction with talin R7 and high affinity. Single point mutants in KANK1 identified from the structure abolished the interaction and enabled us to examine KANK1 enrichment in the adhesion belt. Strikingly, in cells expressing a constitutively active form of vinculin that keeps the FA structure intact even in the presence of myosin inhibitors, KANK1 localizes throughout the entire FA structure even when actomyosin tension is released. We propose a model whereby actomyosin forces on talin eliminate KANK1 from talin binding in the centre of FAs while retaining it at the adhesion periphery.

A comprehensive model of nitrogen-free ordered carbon quantum dots.

We propose and demonstrate a novel range of models to accurately determine the optical properties of nitrogen-free carbon quantum dots (CQDs) with ordered graphene layered structures. We confirm the results of our models against the full range of experimental results for CQDs available from an extensive review of the literature. The models can be equally applied to CQDs with varied sizes and with different oxygen contents in the basal planes of the constituent graphenic sheets. We demonstrate that the experimentally observed blue fluorescent emission of nitrogen-free CQDs can be associated with either small oxidised areas on the periphery of the graphenic sheets, or with sub-nanometre non-functionalised islands of sp2-hybridised carbon with high symmetry confined in the centres of oxidised graphene sheets. Larger and/or less symmetric non-functionalised regions in the centre of functionalised graphene sheet are found to be sources of green and even red fluorescent emission from nitrogen-free CQDs. We also demonstrate an approach to simplify the modelling of the discussed sp2-islands by substitution with equivalent strained polycyclic aromatic hydrocarbons. Additionally, we show that the bandgaps (and photoluminescence) of CQDs are not dependent on either out-of-plane corrugation of the graphene sheet or the spacing between sp2-islands. Advantageously, our proposed models show that there is no need to involve light-emitting polycyclic aromatic molecules (nanographenes) with arbitrary structures grafted to the particle periphery to explain the plethora of optical phenomena observed for CQDs across the full range of experimental works.

Designing a neuroclinical assessment of empathy deficits in psychopathy based on the Zipper Model of Empathy.

The heterogeneity of the literature on empathy highlights its multidimensional and dynamic nature and affects unclear descriptions of empathy in the context of psychopathology. The Zipper Model of Empathy integrates current theories of empathy and proposes that empathy maturity is dependent on whether contextual and personal factors push affective and cognitive processes together or apart. This concept paper therefore proposes a comprehensive battery of physiological and behavioral measures to empirically assess empathy processing according to this model with an application for psychopathic personality. We propose using the following measures to assess each component of this model: (1) facial electromyography; (2) the Emotion Recognition Task; (3) the Empathy Accuracy task and physiological measures (e.g., heart rate); (4) a selection of Theory of Mind tasks and an adapted Dot Perspective Task, and; (5) an adjusted Charity Task. Ultimately, we hope this paper serves as a starting point for discussion and debate on defining and assessing empathy processing, to encourage research to falsify and update this model to improve our understanding of empathy.

The importance of perioperative optimisation to facilitate safe regional anaesthesia and their improved outcomes in fracture neck of femur patients.

BACKGROUND: Hip fractures are common presentations to orthopaedic departments, and their surgical management often results in blood transfusions. Compared with general anaesthesia, regional anaesthesia reduces the need for transfusions and mortality in the wider surgical population. AIMS: In hip fracture patients, our primary outcome measure was to examine any relationship between anaesthetic modality and transfusion rates. The secondary outcome measure was to assess the relationship between anaesthetic modality and one-year mortality. METHODS: A retrospective cohort study of 280 patients was carried out in 2017 and 2018. Data were collected from patient records, local transfusion laboratory and the national hip fracture database. RESULTS: A total of 59.6% had regional and 40.4% general anaesthesia. Regional anaesthesia patients were younger with fewer comorbidities (p < .05). About 19.8% regional and 34.5% general anaesthesia patients received transfusions (odds ratio (OR) = 0.47, p < .05); 13.6% were taking anticoagulants and were less likely to receive a regional anaesthetic (31.6% versus 64%, OR = 0.26, p < .05). One-year mortality was 27% for regional and 37% for general anaesthetic patients (OR = 0.64, p = .09). CONCLUSION: Regional anaesthesia halved the risk of blood transfusion. Anticoagulated patients were 74% less likely to receive regional anaesthetics, but had no additional transfusion risk. With optimisation, a larger proportion of patients could have regional anaesthesia.

Understanding Intracellular Biology to Improve mRNA Delivery by Lipid Nanoparticles.

Poor understanding of intracellular delivery and targeting hinders development of nucleic acid-based therapeutics transported by nanoparticles. Utilizing a siRNA-targeting and small molecule profiling approach with advanced imaging and machine learning biological insights is generated into the mechanism of lipid nanoparticle (MC3-LNP) delivery of mRNA. This workflow is termed Advanced Cellular and Endocytic profiling for Intracellular Delivery (ACE-ID). A cell-based imaging assay and perturbation of 178 targets relevant to intracellular trafficking is used to identify corresponding effects on functional mRNA delivery. Targets improving delivery are analyzed by extracting data-rich phenotypic fingerprints from images using advanced image analysis algorithms. Machine learning is used to determine key features correlating with enhanced delivery, identifying fluid-phase endocytosis as a productive cellular entry route. With this new knowledge, MC3-LNP is re-engineered to target macropinocytosis, and this significantly improves mRNA delivery in vitro and in vivo. The ACE-ID approach can be broadly applicable for optimizing nanomedicine-based intracellular delivery systems and has the potential to accelerate the development of delivery systems for nucleic acid-based therapeutics.

TLN1 contains a cancer-associated cassette exon that alters talin-1 mechanosensitivity.

Talin-1 is the core mechanosensitive adapter protein linking integrins to the cytoskeleton. The TLN1 gene is comprised of 57 exons that encode the 2,541 amino acid TLN1 protein. TLN1 was previously considered to be expressed as a single isoform. However, through differential pre-mRNA splicing analysis, we discovered a cancer-enriched, non-annotated 51-nucleotide exon in TLN1 between exons 17 and 18, which we refer to as exon 17b. TLN1 is comprised of an N-terminal FERM domain, linked to 13 force-dependent switch domains, R1-R13. Inclusion of exon 17b introduces an in-frame insertion of 17 amino acids immediately after Gln665 in the region between R1 and R2 which lowers the force required to open the R1-R2 switches potentially altering downstream mechanotransduction. Biochemical analysis of this isoform revealed enhanced vinculin binding, and cells expressing this variant show altered adhesion dynamics and motility. Finally, we showed that the TGF-ß/SMAD3 signaling pathway regulates this isoform switch. Future studies will need to consider the balance of these two TLN1 isoforms.

DNA-binding and regulatory properties of the transcription factor and putative tumor suppressor p150(Sal2).

The product of the SALL2 protein p150(Sal2) is a multi-zinc finger transcription factor with growth arrest and proapoptotic functions that overlap those of p53. Its DNA-binding properties are unknown. We have used a modified SELEX procedure with purified p150(Sal2) and a pool of oligonucleotides of random sequence to identify those that are bound preferentially by p150(Sal2). The consensus sequence for optimal binding in vitro is GGG(T/C)GGG, placing p150(Sal2) among a large group of GC box-binding proteins including the Sp1 family of transcription factors. A triple zinc finger motif in p150(Sal2) similar to that in Sp1 is required for DNA binding. p150(Sal2) and Sp1 show evidence of co-operative binding in vitro and of interaction in vivo. p150(Sal2), a known activator of the CDK inhibitor p21(Cip1/Waf1) (p21), binds to regions of the human p21 promoter that contain variations of the consensus sequence in multiple copies. p150(Sal2) is also shown to bind to the BAX promoter with similar elements and to activate its expression following an apoptotic stimulus. These results demonstrate binding of p150(Sal2) to two natural promoters with GC elements related to the optimal binding sequence defined in vitro and whose regulation is important for suppression of tumor growth.

Polyoma virus-induced osteosarcomas in inbred strains of mice: host determinants of metastasis.

The mouse polyoma virus induces a broad array of solid tumors in mice of many inbred strains. In most strains tumors grow rapidly but fail to metastasize. An exception has been found in the Czech-II/Ei mouse in which bone tumors metastasize regularly to the lung. These tumors resemble human osteosarcoma in their propensity for pulmonary metastasis. Cell lines established from these metastatic tumors have been compared with ones from non-metastatic osteosarcomas arising in C3H/BiDa mice. Osteopontin, a chemokine implicated in migration and metastasis, is known to be transcriptionally induced by the viral middle T antigen. Czech-II/Ei and C3H/BiDa tumor cells expressed middle T and secreted osteopontin at comparable levels as the major chemoattractant. The tumor cell lines migrated equally well in response to recombinant osteopontin as the sole attractant. An important difference emerged in assays for invasion in which tumor cells from Czech-II/Ei mice were able to invade across an extracellular matrix barrier while those from C3H/BiDa mice were unable to invade. Invasive behavior was linked to elevated levels of the metalloproteinase MMP-2 and of the transcription factor NFAT. Inhibition of either MMP-2 or NFAT inhibited invasion by Czech-II/Ei osteosarcoma cells. The metastatic phenotype is dominant in F1 mice. Osteosarcoma cell lines from F1 mice expressed intermediate levels of MMP-2 and NFAT and were invasive. Osteosarcomas in Czech-II/Ei mice retain functional p53. This virus-host model of metastasis differs from engineered models targeting p53 or pRb and provides a system for investigating the genetic and molecular basis of bone tumor metastasis in the absence of p53 loss.