Building momentum through networks: Bioimaging across the Americas.

In September 2023, the two largest bioimaging networks in the Americas, Latin America Bioimaging (LABI) and BioImaging North America (BINA), came together during a 1-week meeting in Mexico. This meeting provided opportunities for participants to interact closely with decision-makers from imaging core facilities across the Americas. The meeting was held in a hybrid format and attended in-person by imaging scientists from across the Americas, including Canada, the United States, Mexico, Colombia, Peru, Argentina, Chile, Brazil and Uruguay. The aims of the meeting were to discuss progress achieved over the past year, to foster networking and collaborative efforts among members of both communities, to bring together key members of the international imaging community to promote the exchange of experience and expertise, to engage with industry partners, and to establish future directions within each individual network, as well as common goals. This meeting report summarises the discussions exchanged, the achievements shared, and the goals set during the LABIxBINA2023: Bioimaging across the Americas meeting.

Harmonizing the Generation and Pre-publication Stewardship of FAIR Image data.

Together with the molecular knowledge of genes and proteins, biological images promise to significantly enhance the scientific understanding of complex cellular systems and to advance predictive and personalized therapeutic products for human health. For this potential to be realized, quality-assured image data must be shared among labs at a global scale to be compared, pooled, and reanalyzed, thus unleashing untold potential beyond the original purpose for which the data was generated. There are two broad sets of requirements to enable image data sharing in the life sciences. One set of requirements is articulated in the companion White Paper entitled "Enabling Global Image Data Sharing in the Life Sciences," which is published in parallel and addresses the need to build the cyberinfrastructure for sharing the digital array data (arXiv:2401.13023 [q-bio.OT], https://doi.org/10.48550/arXiv.2401.13023). In this White Paper, we detail a broad set of requirements, which involves collecting, managing, presenting, and propagating contextual information essential to assess the quality, understand the content, interpret the scientific implications, and reuse image data in the context of the experimental details. We start by providing an overview of the main lessons learned to date through international community activities, which have recently made considerable progress toward generating community standard practices for imaging Quality Control (QC) and metadata. We then provide a clear set of recommendations for amplifying this work. The driving goal is to address remaining challenges, and democratize access to common practices and tools for a spectrum of biomedical researchers, regardless of their expertise, access to resources, and geographical location.

Community-developed checklists for publishing images and image analyses.

Images document scientific discoveries and are prevalent in modern biomedical research. Microscopy imaging in particular is currently undergoing rapid technological advancements. However, for scientists wishing to publish obtained images and image-analysis results, there are currently no unified guidelines for best practices. Consequently, microscopy images and image data in publications may be unclear or difficult to interpret. Here, we present community-developed checklists for preparing light microscopy images and describing image analyses for publications. These checklists offer authors, readers and publishers key recommendations for image formatting and annotation, color selection, data availability and reporting image-analysis workflows. The goal of our guidelines is to increase the clarity and reproducibility of image figures and thereby to heighten the quality and explanatory power of microscopy data.

Community-developed checklists for publishing images and image analyses.

Images document scientific discoveries and are prevalent in modern biomedical research. Microscopy imaging in particular is currently undergoing rapid technological advancements. However for scientists wishing to publish the obtained images and image analyses results, there are to date no unified guidelines. Consequently, microscopy images and image data in publications may be unclear or difficult to interpret. Here we present community-developed checklists for preparing light microscopy images and image analysis for publications. These checklists offer authors, readers, and publishers key recommendations for image formatting and annotation, color selection, data availability, and for reporting image analysis workflows. The goal of our guidelines is to increase the clarity and reproducibility of image figures and thereby heighten the quality and explanatory power of microscopy data is in publications.

Micro-Meta App: an interactive tool for collecting microscopy metadata based on community specifications.

For quality, interpretation, reproducibility and sharing value, microscopy images should be accompanied by detailed descriptions of the conditions that were used to produce them. Micro-Meta App is an intuitive, highly interoperable, open-source software tool that was developed in the context of the 4D Nucleome (4DN) consortium and is designed to facilitate the extraction and collection of relevant microscopy metadata as specified by the recent 4DN-BINA-OME tiered-system of Microscopy Metadata specifications. In addition to substantially lowering the burden of quality assurance, the visual nature of Micro-Meta App makes it particularly suited for training purposes.

Replication Study: Biomechanical remodeling of the microenvironment by stromal caveolin-1 favors tumor invasion and metastasis.

As part of the Reproducibility Project: Cancer Biology we published a Registered Report (Fiering et al., 2015) that described how we intended to replicate selected experiments from the paper 'Biomechanical remodeling of the microenvironment by stromal caveolin-1 favors tumor invasion and metastasis' (Goetz et al., 2011). Here we report the results. Primary mouse embryonic fibroblasts (pMEFs) expressing caveolin 1 (Cav1WT) demonstrated increased extracellular matrix remodeling in vitro compared to Cav1 deficient (Cav1KO) pMEFs, similar to the original study (Goetz et al., 2011). In vivo, we found higher levels of intratumoral stroma remodeling, determined by fibronectin fiber orientation, in tumors from cancer cells co-injected with Cav1WT pMEFs compared to cancer cells only or cancer cells plus Cav1KO pMEFs, which were in the same direction as the original study (Supplemental Figure S7C; Goetz et al., 2011), but not statistically significant. Primary tumor growth was similar between conditions, like the original study (Supplemental Figure S7Ca; Goetz et al., 2011). We found metastatic burden was similar between Cav1WT and Cav1KO pMEFs, while the original study found increased metastases with Cav1WT (Figure 7C; Goetz et al., 2011); however, the duration of our in vivo experiments (45 days) were much shorter than in the study by Goetz et al. (2011) (75 days). This makes it difficult to interpret the difference between the studies as it is possible that the cells required more time to manifest the difference between treatments observed by Goetz et al. We also found a statistically significant negative correlation of intratumoral remodeling with metastatic burden, while the original study found a statistically significant positive correlation (Figure 7Cd; Goetz et al., 2011), but again there were differences between the studies in terms of the duration of the metastasis studies and the imaging approaches that could have impacted the outcomes. Finally, we report meta-analyses for each result.

Registered report: Biomechanical remodeling of the microenvironment by stromal caveolin-1 favors tumor invasion and metastasis.

The Reproducibility Project: Cancer Biology seeks to address growing concerns about reproducibility in scientific research by conducting replicating selected results from a number of high-profile papers in the field of cancer biology. The papers, which were published between 2010 and 2012 were selected on the basis of citations and Altimetric scores (Errington et al., 2014). This Registered report describes the proposed replication plan of key experiments from 'Biomechanical remodeling of the microenvironment by stromal caveolin-1 favors tumor invasion and metastasis' by Goetz and colleagues, published in Cell in 2011 (Goetz et al., 2011). The key experiments being replicated are those reported in Figures 7C (a-d), Supplemental Figure S2A, and Supplemental Figure S7C (a-c) (Goetz et al., 2011). In these experiments, which are a subset of all the experiments reported in the original publication, Goetz and colleagues show in a subcutaneous xenograft model that stromal caveolin-1 remodels the intratumoral microenvironment, which is correlated with increased metastasis formation. The Reproducibility Project: Cancer Biology is a collaboration between the Center for Open Science and Science Exchange and the results of the replications will be published in eLife.

RIG-I-mediated antiviral signaling is inhibited in HIV-1 infection by a protease-mediated sequestration of RIG-I.

The rapid induction of type I interferon (IFN) is essential for establishing innate antiviral responses. During infection, cytoplasmic viral RNA is sensed by two DExD/H box RNA helicases, RIG-I and MDA5, ultimately driving IFN production. Here, we demonstrate that purified genomic RNA from HIV-1 induces a RIG-I-dependent type I IFN response. Both the dimeric and monomeric forms of HIV-1 were sensed by RIG-I, but not MDA5, with monomeric RNA, usually found in defective HIV-1 particles, acting as a better inducer of IFN than dimeric RNA. However, despite the presence of HIV-1 RNA in the de novo infection of monocyte-derived macrophages, HIV-1 replication did not lead to a substantial induction of IFN signaling. We demonstrate the existence of an evasion mechanism based on the inhibition of the RIG-I sensor through the action of the HIV-1 protease (PR). Indeed, the ectopic expression of PR resulted in the inhibition of IFN regulatory factor 3 (IRF-3) phosphorylation and decreased expression of IFN and interferon-stimulated genes. A downregulation of cytoplasmic RIG-I levels occurred in cells undergoing a single-cycle infection with wild-type provirus BH10 but not in cells transfected with a protease-deficient provirus, BH10-PR(-). Cellular fractionation and confocal microscopy studies revealed that RIG-I translocated from the cytosol to an insoluble fraction during the de novo HIV-1 infection of monocyte-derived macrophages, in the presence of PR. The loss of cytoplasmic RIG-I was prevented by the lysosomal inhibitor E64, suggesting that PR targets RIG-I to the lysosomes. This study reveals a novel PR-dependent mechanism employed by HIV-1 to counteract the early IFN response to viral RNA in infected cells.

Ubiquitin-regulated recruitment of IkappaB kinase epsilon to the MAVS interferon signaling adapter.

Induction of the antiviral interferon response is initiated upon recognition of viral RNA structures by the RIG-I or Mda-5 DEX(D/H) helicases. A complex signaling cascade then converges at the mitochondrial adapter MAVS, culminating in the activation of the IRF and NF-kappaB transcription factors and the induction of interferon gene expression. We have previously shown that MAVS recruits IkappaB kinase epsilon (IKKepsilon) but not TBK-1 to the mitochondria following viral infection. Here we map the interaction of MAVS and IKKepsilon to the C-terminal region of MAVS and demonstrate that this interaction is ubiquitin dependent. MAVS is ubiquitinated following Sendai virus infection, and K63-linked ubiquitination of lysine 500 (K500) of MAVS mediates recruitment of IKKepsilon to the mitochondria. Real-time PCR analysis reveals that a K500R mutant of MAVS increases the mRNA level of several interferon-stimulated genes and correlates with increased NF-kappaB activation. Thus, recruitment of IKKepsilon to the mitochondria upon MAVS K500 ubiquitination plays a modulatory role in the cascade leading to NF-kappaB activation and expression of inflammatory and antiviral genes. These results provide further support for the differential role of IKKepsilon and TBK-1 in the RIG-I/Mda5 pathway.

Live-cell microscopy - tips and tools.

Imaging of living cells and tissue is now common in many fields of the life and physical sciences, and is instrumental in revealing a great deal about cellular dynamics and function. It is crucial when performing such experiments that cell viability is at the forefront of any measurement to ensure that the physiological and biological processes that are under investigation are not altered in any way. Many cells and tissues are not normally exposed to light during their life cycle, so it is important for microscopy applications to minimize light exposure, which can cause phototoxicity. To ensure minimal light exposure, it is crucial that microscope systems are optimized to collect as much light as possible. This can be achieved using superior-quality optical components and state-of-the-art detectors. This Commentary discusses how to set up a suitable environment on the microscope stage to maintain living cells. There is also a focus on general and imaging-platform-specific ways to optimize the efficiency of light throughput and detection. With an efficient optical microscope and a good detector, the light exposure can be minimized during live-cell imaging, thus minimizing phototoxicity and maintaining cell viability. Brief suggestions for useful microscope accessories as well as available fluorescence tools are also presented. Finally, a flow chart is provided to assist readers in choosing the appropriate imaging platform for their experimental systems.

Recruitment of an interferon molecular signaling complex to the mitochondrial membrane: disruption by hepatitis C virus NS3-4A protease.

Recent advances in the understanding of the signaling pathways leading to the host antiviral response to hepatitis C virus (HCV), the mechanisms used by HCV to evade the immune response, and the development of small molecule inhibitors of HCV have generated optimism that novel therapeutic approaches to control HCV disease may soon be available. HCV infection is detected by the cytoplasmic, RNA helicase RIG-I that plays an essential role in signaling to the host antiviral response. Recently the adapter molecule that links RIG-I sensing of incoming viral RNA to downstream signaling and gene activation events was characterized by four different groups: MAVS/IPS-1-1/VISA/Cardif contains an amino-terminal CARD domain and carboxyl-terminal mitochondrial transmembrane sequence that localizes to the mitochondrial membrane. Furthermore, the hepatitis C virus NS3-4A protease complex specifically targets MAVS/IPS-1/VISA/Cardif for cleavage as part of its immune evasion strategy. Using a combination of biochemical analysis, subcellular fractionation and confocal microscopy, we demonstrate that: (1) NS3-4A cleavage of MAVS/IPS-1/VISA/Cardif causes relocation from the mitochondrial membrane to the cytosolic fraction, resulting in disruption of signaling to the antiviral immune response; (2) disruption requires a function NS3-4A protease; (3) a point mutant of MAVS/IPS-1/VISA/Cardif (Cys508Ala) is not cleaved from the mitochondria by active protease; and (4) the virus-induced IKK epsilon kinase, but not TBK1, co-localizes strongly with MAVS at the mitochondrial membrane and the localization of both molecules is disrupted by NS3-4A expression. These observations provide an outline of the mechanism by which HCV evades the IFN antiviral response.

Dissociation of a MAVS/IPS-1/VISA/Cardif-IKKepsilon molecular complex from the mitochondrial outer membrane by hepatitis C virus NS3-4A proteolytic cleavage.

Intracellular RNA virus infection is detected by the cytoplasmic RNA helicase RIG-I that plays an essential role in signaling to the host antiviral response. Recently, the adapter molecule that links RIG-I sensing of incoming viral RNA to downstream signaling and gene activation events was characterized by four different groups; MAVS/IPS-1-1/VISA/Cardif contains an amino-terminal CARD domain and a carboxyl-terminal mitochondrial transmembrane sequence that localizes to the mitochondrial membrane. Furthermore, the hepatitis C virus NS3-4A protease complex specifically targets MAVS/IPS-1/VISA/Cardif for cleavage as part of its immune evasion strategy. With a novel search program written in python, we also identified an uncharacterized protein, KIAA1271 (K1271), containing a single CARD-like domain at the N terminus and a Leu-Val-rich C terminus that is identical to that of MAVS/IPS-1/VISA/Cardif. Using a combination of biochemical analysis, subcellular fractionation, and confocal microscopy, we now demonstrate that NS3-4A cleavage of MAVS/IPS-1/VISA/Cardif/K1271 results in its dissociation from the mitochondrial membrane and disrupts signaling to the antiviral immune response. Furthermore, virus-induced IKKepsilon kinase, but not TBK1, colocalized strongly with MAVS at the mitochondrial membrane, and the localization of both molecules was disrupted by NS3-4A expression. Mutation of the critical cysteine 508 to alanine was sufficient to maintain mitochondrial localization of MAVS/IPS-1/VISA/Cardif and IKKepsilon in the presence of NS3-4A. These observations provide an outline of the mechanism by which hepatitis C virus evades the interferon antiviral response.

Focal adhesion kinase is required for bombesin-induced prostate cancer cell motility.

Clinical evidence links neuroendocrine differentiation (NED) to prostate cancer progression. In the prostate carcinoma PC-3 cell model, the action of the gastrin releasing peptide (GRP) analog, bombesin (BN), on the activation of focal adhesion kinase (FAK) and invasiveness suggests that this kinase might favor metastasis. Given that components of the FAK signalling pathway are also up regulated in prostate cancer, the aim of the present investigation was to test if FAK function is required for BN-induced motility in PC-3 cells. In wound assays designed to investigate the fate of FAK in cells undergoing BN-induced motility, it was observed that BN treatment resulted in relocalization of FAK in focal contacts concomitantly with its tyrosine phosphorylation on residue 397 (FAK [pY(397)]) and with the formation of actin lamellipodia. Moreover, BN-induced cell motility was significantly reduced in the presence of FAK inhibitors (either anti-FAK [pY(397)] antibody or FRNK, the FAK-related non-kinase). Altogether, these observations point towards a critical role for FAK in the action of BN on PC-3 cell motility.