Critical cancer pathways often cannot be targeted because of limited efficiency crossing cell membranes. Here we report the development of a Salmonella-based intracellular delivery system to address ...this challenge. We engineer genetic circuits that (1) activate the regulator flhDC to drive invasion and (2) induce lysis to release proteins into tumor cells. Released protein drugs diffuse from Salmonella containing vacuoles into the cellular cytoplasm where they interact with their therapeutic targets. Control of invasion with flhDC increases delivery over 500 times. The autonomous triggering of lysis after invasion makes the platform self-limiting and prevents drug release in healthy organs. Bacterial delivery of constitutively active caspase-3 blocks the growth of hepatocellular carcinoma and lung metastases, and increases survival in mice. This success in targeted killing of cancer cells provides critical evidence that this approach will be applicable to a wide range of protein drugs for the treatment of solid tumors.
The prefrontal cortex is a higher brain region that regulates thought, behavior, and emotion using representational knowledge, operations often referred to as working memory. We tested the influence ...of protein kinase C (PKC) intracellular signaling on prefrontal cortical cognitive function and showed that high levels of PKC activity in prefrontal cortex, as seen for example during stress exposure, markedly impair behavioral and electrophysiological measures of working memory. These data suggest that excessive PKC activation can disrupt prefrontal cortical regulation of behavior and thought, possibly contributing to signs of prefrontal cortical dysfunction such as distractibility, impaired judgment, impulsivity, and thought disorder.
Coastal hillslopes often host higher concentrations of earthquake-induced landslides than those further inland, but few studies have investigated the reasons for this occurrence. As a result, it is ...unclear if regional earthquake-induced landslide susceptibility models trained primarily on inland hillslopes are effective predictors of coastal susceptibility. The 2016 Mw 7.8 Kaikōura earthquake on the northeastern South Island of New Zealand resulted in ca. 1600 landslides > 50 m2 on slopes > 15∘ within 1 km of the coast, contributing to an order of magnitude greater landslide source area density than inland hillslopes within 1 to 3 km of the coast. In this study, logistic regression modelling is used to investigate how landslide susceptibility differs between coastal and inland hillslopes and to determine the factors that drive the distribution of coastal landslides initiated by the 2016 Kaikōura earthquake. Strong model performance (area under the receiver operator characteristic curve or AUC of ca. 0.80 to 0.92) was observed across eight models, which adopt four simplified geology types. The same landslide susceptibility factors, primarily geology, steep slopes, and ground motion, are strong model predictors for both inland and coastal landslide susceptibility in the Kaikōura region. In three geology types (which account for more than 90 % of landslide source areas), a 0.03 or less drop in model AUC is observed when predicting coastal landslides using inland-trained models. This suggests little difference between the features driving inland and coastal landslide susceptibility in the Kaikōura region. Geology is similarly distributed between inland and coastal hillslopes, and peak ground acceleration (PGA) is generally lower in coastal hillslopes. Slope angle, however, is significantly higher in coastal hillslopes and provides the best explanation for the high density of coastal landslides during the 2016 Kaikōura earthquake. Existing regional earthquake-induced landslide susceptibility models trained on inland hillslopes using common predictive features are likely to capture this signal without additional predictive variables. Interestingly, in the Kaikōura region, most coastal hillslopes are isolated from the ocean by uplifted shore platforms. Enhanced coastal landslide susceptibility from this event appears to be a legacy effect of past erosion from wave action, which preferentially steepened these coastal hillslopes.
Modeling suggests that steep coastal regions will experience increasingly rapid erosion related to climate-change-induced sea level rise. Earthquakes can also cause intense episodes of coastal cliff ...retreat, but coseismic failures are rarely captured in the historical record used to calibrate most cliff retreat forecast models. Here, we disaggregate cliff-top retreat related to strong ground motion and non-seismic sources, providing a unique window into earthquake contributions to multidecadal coastal cliff retreat. Widespread landsliding and up to ca. 19 m of coastal cliff-top retreat occurred in the area of Conway Flat during the 2016 Kaikōura (New Zealand) earthquake despite relatively low (ca. 0.2 g) peak ground accelerations. While coastal cliff-top retreat has been spatially and temporally variable over the historical record, aerial imagery suggests that large earthquake-induced landslide-triggering events disproportionately contribute to an average 0.25 m yr−1 retreat at Conway Flat. The 2016 Kaikōura earthquake represents ca. 24 % of the total cliff-top retreat over 72 years and ca. 39 % of cliff-top retreat over 56 years. Additionally, we infer that significant retreat between 1950 and 1966 is the result of local seismicity. Together these two events account for ca. 57 % of cliff-top retreat over 72 years. Earthquake-related debris piles at the base of the cliffs have been rapidly eroded since the 2016 Kaikōura earthquake (more than 25 % loss of debris volume in 5 years), and there will likely be little evidence of the earthquake within the next decade. In regions with similar lithologic and coastal conditions, evidence of past widespread single-event cliff-top retreat may be limited or non-existent. The results demonstrate that cliff-top retreat projections using historical records may significantly underestimate true retreat rates in seismically active regions.
Immunotherapies have shown great promise, but are not effective for all tumors types and are effective in less than 3% of patients with pancreatic ductal adenocarcinomas (PDAC). To make an immune ...treatment that is effective for more cancer patients and those with PDAC specifically, we genetically engineered Salmonella to deliver exogenous antigens directly into the cytoplasm of tumor cells. We hypothesized that intracellular delivery of an exogenous immunization antigen would activate antigen-specific CD8 T cells and reduce tumors in immunized mice.
To test this hypothesis, we administered intracellular delivering (ID) Salmonella that deliver ovalbumin as a model antigen into tumor-bearing, ovalbumin-vaccinated mice. ID Salmonella delivers antigens by autonomously lysing in cells after the induction of cell invasion.
We showed that the delivered ovalbumin disperses throughout the cytoplasm of cells in culture and in tumors. This delivery into the cytoplasm is essential for antigen cross-presentation. We showed that co-culture of ovalbumin-recipient cancer cells with ovalbumin-specific CD8 T cells triggered a cytotoxic T cell response. After the adoptive transfer of OT-I CD8 T cells, intracellular delivery of ovalbumin reduced tumor growth and eliminated tumors. This effect was dependent on the presence of the ovalbumin-specific T cells. Following vaccination with the exogenous antigen in mice, intracellular delivery of the antigen cleared 43% of established KPC pancreatic tumors, increased survival, and prevented tumor re-implantation.
This response in the immunosuppressive KPC model demonstrates the potential to treat tumors that do not respond to checkpoint inhibitors, and the response to re-challenge indicates that new immunity was established against intrinsic tumor antigens. In the clinic, ID Salmonella could be used to deliver a protein antigen from a childhood immunization to refocus pre-existing T cell immunity against tumors. As an off-the-shelf immunotherapy, this bacterial system has the potential to be effective in a broad range of cancer patients.
Management actions to protect endangered species and conserve ecosystem function may not always be in precise alignment. Efforts to recover the California Ridgway’s Rail (Rallus obsoletus obsoletus; ...hereafter, California rail), a federally and state-listed species, and restoration of tidal marsh ecosystems in the San Francisco Bay estuary provide a prime example of habitat restoration that has conflicted with species conservation. On the brink of extinction from habitat loss and degradation, and non-native predators in the 1990s, California rail populations responded positively to introduction of a non-native plant, Atlantic cordgrass (Spartina alterniflora). California rail populations were in substantial decline when the non-nativeSpartinawas initially introduced as part of efforts to recover tidal marshes. Subsequent hybridization with the native Pacific cordgrass (Spartina foliosa) boosted California rail populations by providing greater cover and increased habitat area. The hybrid cordgrass (S. alterniflora × S. foliosa) readily invaded tidal mudflats and channels, and both crowded out native tidal marsh plants and increased sediment accretion in the marsh plain. This resulted in modification of tidal marsh geomorphology, hydrology, productivity, and species composition. Our results show that denser California rail populations occur in invasiveSpartinathan in nativeSpartinain San Francisco Bay. Herbicide treatment between 2005 and 2012 removed invasiveSpartinafrom open intertidal mud and preserved foraging habitat for shorebirds. However, removal of invasiveSpartinacaused substantial decreases in California rail populations. Unknown facets of California rail ecology, undesirable interim stages of tidal marsh restoration, and competing management objectives among stakeholders resulted in management planning for endangered species or ecosystem restoration that favored one goal over the other. We have examined this perceived conflict and propose strategies for moderating harmful effects of restoration while meeting the needs of both endangered species and the imperiled native marsh ecosystem.
South Africa has a high disease burden resulting from communicable and non-communicable diseases. Current therapeutic interventions rarely result in a cure and the associated lifelong treatment ...places a considerable strain on an overburdened health sector. Gene and cell therapies present novel alternatives to disease management, offering the promise of a single treatment and a lifelong cure. Although challenges remain, investment in the field has started to bear fruit, with a number of gene and cell therapeutics reaching the market in the past decade. To take full advantage of these developments, it is important that a proactive approach to nurturing appropriate human and material resources is adopted in the country.
The objective of this study was to use confocal fluorescence recovery after photobleaching (FRAP) to examine the specific and dose-dependent effect of proteoglycan 4 (PRG4) on hyaluronan (HA) ...solutions of different molecular weight; and assess the effect of reduction and alkylation (R/A) of PRG4 on its effects on HA solutions.
Confocal FRAP was used to determine the diffusion coefficient of fluorescein isothiocyanate (FITC)-dextran tracer (D
) through 1500 kDa and 500 kDa HA solutions (0-3.3 mg/ml) ± PRG4 or a control protein, bovine serum albumin (BSA), at physiological (450 μg/ml) or pathophysiological (45 μg/ml) concentrations. The effect of PRG4 or R/A PRG4 on 1500 kDa HA solutions was also investigated. Empirical constants obtained from fitting data to the universal scaling equation were used to calculate the average distribution of apparent mesh sizes.
PRG4 at both 45 and 450 μg/ml slowed the diffusion of the FITC-dextran tracer for all concentrations of HA and caused a decrease in the apparent mesh size within the HA solution. This effect was specific to PRG4, not observed with BSA, but not dependent on its tertiary/quaternary structure as the effect remained after R/A of PRG4.
These results demonstrate that PRG4 can significantly alter the solution properties of HA; PRG4 essentially reduced the permeability of the HA network. This effect may be due to PRG4 entangling HA molecules through binding and/or HA crowding PRG4 molecules into a self-assembled network. Collectively these findings contribute to the understanding of PRG4 and HA interaction(s) in solution and therefore the function of SF in diarthroidal joints.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Investigations into the biophysical properties of single molecules traditionally involve well defined in vitro systems where parameters such as solvent viscosity and applied forces are known a ...priori. These systems provide means to develop models describing the polymers response to a variety of conditions, including the entropically driven relaxation of a stretched biopolymer upon release of the tension inducing force. While these techniques have proven instrumental for recent advancements in the fields of polymer physics and biophysics, how applicable they are to life inside the cell remains poorly understood. Here we report an investigation of in vivo stretched polymer relaxation dynamics using chromatin relaxation following the breakage of a dicentric chromosome subjected to microtubule-based spindle forces. Additionally, we have developed an in vitro system used to verify the conformations observed during the in vivo relaxation, including the predicted but previously unidentified taut conformation. These observations motivate our use of existing polymer models to determine both the in vivo viscosity as seen by the relaxing chromatin and the tension force applied by the microtubule-based spindle in vivo. As a result, the technique described herein may be used as a biophysical strategy to probe the intranuclear environment.
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