•Ca2+i in Df1/+ astrocytes was evaluated with Bayesian kinetic inference.•The activity of SERCA is altered in Df1/+ astrocytes.•Inhibition of SERCA in control astrocytes phenocopies Df1/+ ...astrocytes.•Altered activity of SERCA is a driver of calcium kinetics in Df1/+ astrocytes.•Bayesian kinetic inference is useful for mechanistic studies in astrocytes.
Methods for deriving mechanistic information from intracellular calcium dynamics have largely been applied to neuronal data despite the knowledge of roles of glial cells in behavior, cognition, and psychiatric disorders. Using calcium imaging, computer vision, and Bayesian kinetic inference (BKI), we analyzed calcium dynamics in primary astrocytes derived from control or Df1/+ mice, a model of 22q11.2 deletion (DiGeorge syndrome). Inference of the highest-likelihood molecular kinetic characteristics of intracellular calcium dynamics identified changes in the activity of the sarcoendoplasmic reticulum calcium ATPase (SERCA). Application of a SERCA inhibitor to wild-type astrocytes reproduced the differences detected in Df1/+ astrocytes. Our work reveals the molecular changes driving the calcium kinetics in astrocytes from a 22q11.2 deletion model. BKI can be useful for mechanistically dissecting calcium dynamics in glial cells and formulating and testing hypotheses about underlying molecular mechanisms.
High fat consumption can enhance metastasis and decrease survival in prostate cancer, but the picture remains incomplete on the epidemiological and cell-biological level, impeding progress toward ...individualized recommendations in the clinic. Recent work has highlighted the role of exosomes secreted by prostate cancer cells in the progression of the disease, particularly in metastatic invasion, and also the utility of targeting these extracellular vesicles for diagnostics, as carriers of disease progression markers. Here, we investigated the question of a potential impact of the chief nutritional saturated fatty acid on the exosome secretion. Palmitic acid decreased the secretion of exosomes in human prostate cancer cells in vitro in a concentration-dependent manner. At the same time, the content of some prospective metastatic markers in the secreted exosomal fraction was also reduced, as was the ability of the cells to invade across extracellular matrix barriers. While by themselves our in vitro results imply that on the cell level, palmitic acid may be beneficial vis-à-vis the course of the disease, they also suggest that, by virtue of the decreased biomarker secretion, palmitic acid has the potential to cause unjustified deprioritization of treatment in obese and lipidemic men.
Recently, there have been a number of developments in the fields of calcium and nuclear signaling that point to new avenues for a more effective diagnosis and treatment of prostate cancer. An example ...is the discovery of new classes of molecules involved in calcium-regulated nuclear import and nuclear calcium signaling, from the G protein-coupled receptor (GPCR) and myosin families. This review surveys the new state of the calcium and nuclear signaling fields with the aim of identifying the unifying themes that hold out promise in the context of the problems presented by prostate cancer. Genomic perturbations, kinase cascades, developmental pathways, and channels and transporters are covered, with an emphasis on nuclear transport and functions. Special attention is paid to the molecular mechanisms behind prostate cancer progression to the malignant forms and the unfavorable response to anti-androgen treatment. The survey leads to some new hypotheses that connect heretofore disparate results and may present a translational interest.
Progression of prostate cancer to lethal forms is marked by emergence of hormone-independent proliferation of the cancer cells. Nutritional and epidemiological studies have indicated that prostate ...cancer progression is correlated with the consumption of polyunsaturated fatty acids (PUFA). To shed additional light on the cell-level mechanisms of the observed correlation, we compared the sensitivity of hormone-dependent and hormone-independent prostate cancer cells to growth medium supplementation with free PUFAs in a cell proliferation and viability assay. Our data show that the hormone-dependent cells are comparatively insensitive to various PUFAs, at the same time as the growth and viability of hormone-independent cells lines are strongly inhibited by most of the tested PUFAs, whether n-3 or n-6. We speculate that this difference may be at least partially responsible for the observed effects of specific dietary lipids in prostate cancer. The new data strengthen the case for dietary intervention as part of potential new therapeutic strategies seeking to impede prostate cancer progression.
Early diagnosis of prostate cancer is a challenging issue due to the lack of specific markers. Therefore, a sensitive diagnostic marker that is expressed or upregulated exclusively in prostate cancer ...cells would facilitate diagnostic procedures and ensure a better outcome. We evaluated the expression of myosin 1C isoform A in 5 prostate cell lines, 41 prostate cancer cases, and 11 benign hyperplasias. We analyzed the expression of 12 surface molecules on prostate cancer cells by flow cytometry and analyzed whether high or low myosin 1C isoform A expression could be attributed to a distinct phenotype of prostate cancer cells. Median myosin 1C isoform A expression in prostate cancer samples and cancer cell lines was 2 orders of magnitude higher than in benign prostate hyperplasia. Based on isoform A expression, we could also distinguish clinical stage 2 from clinical stage 3. Among cell lines, PC-3 cells with the highest myosin 1C isoform A level had diminished numbers of CD10/CD13-positive cells and increased numbers of CD29 (integrin beta1), CD38, CD54 (ICAM1) positive cells. The surface phenotype of clinical samples was similar to prostate cancer cell lines with high isoform A expression and could be described as CD10-/CD13- with heterogeneous expression of other markers. Both for cell lines and cancer specimens we observed the strong correlation of high myosin 1C isoform A mRNA expression and elevated levels of CD29 and CD54, suggesting a more adhesive phenotype for cells with high isoform A expression. Compared to normal tissue, prostate cancer samples had also reduced numbers of CD24- and CD38-positive cells. Our data suggest that a high level of myosin 1C isoform A is a specific marker both for prostate cancer cells and prostate cancer cell lines. High expression of isoform A is associated with less activated (CD24/CD38 low) and more adhesive (CD29/CD54 high) surface phenotype compared to benign prostate tissue.
Many cell cytoskeletons include an aster of microtubules, with the centrosome serving as the focal point. The position of the centrosome within the cell is important in such directional activities as ...wound closure and interactions of immune cells. Here we analyzed the centrosome positioning as it is dictated by microtubule elasticity alone in a mechanical model of an intrinsically fully symmetric microtubule aster. We demonstrate that the symmetry and the central position of the centrosome are unstable. The equilibrium deviation of the centrosome from the center is approximately proportional to the difference of the microtubule length and cell radius. The proportionality coefficient is 1 in flat cells and 2 in three-dimensional cells. The loss of symmetry is irreversible, and in general, the equilibrium form of the aster exhibits memory of past perturbations. The equilibrium position of the centrosome as a function of the microtubule length exhibits hysteresis, and the history of the length variation is reflected in the aster form. These properties of the simple aster of elastic microtubules must be taken into account in the analysis of more comprehensive theoretical models, and in the design and interpretation of experiments addressing the complex process of cytoskeleton morphogenesis.
Mechanisms controlling microtubule dynamics at the cell cortex play a crucial role in cell morphogenesis and neuronal development. Here, we identified kinesin-4 KIF21A as an inhibitor of microtubule ...growth at the cell cortex. In vitro, KIF21A suppresses microtubule growth and inhibits catastrophes. In cells, KIF21A restricts microtubule growth and participates in organizing microtubule arrays at the cell edge. KIF21A is recruited to the cortex by KANK1, which coclusters with liprin-α1/β1 and the components of the LL5β-containing cortical microtubule attachment complexes. Mutations in KIF21A have been linked to congenital fibrosis of the extraocular muscles type 1 (CFEOM1), a dominant disorder associated with neurodevelopmental defects. CFEOM1-associated mutations relieve autoinhibition of the KIF21A motor, and this results in enhanced KIF21A accumulation in axonal growth cones, aberrant axon morphology, and reduced responsiveness to inhibitory cues. Our study provides mechanistic insight into cortical microtubule regulation and suggests that altered microtubule dynamics contribute to CFEOM1 pathogenesis.
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•KIF21A coclusters with KANK1, LL5β, liprin-α1, and liprin-β1 at the cell cortex•KIF21A inhibits microtubule growth in vitro and at the cell cortex•CFEOM1-associated mutations in KIF21A relieve its autoinhibition•Increased KIF21A activity affects axonal morphology and growth cone dynamics
KIF21A kinesin is mutated in the neurodevelopmental disorder CFEOM1. Van der Vaart et al. show that KIF21A acts as a microtubule polymerization inhibitor and that CFEOM1-associated mutations relieve KIF21A autoinhibition. Changes in microtubule dynamics caused by the increased activity of KIF21A may contribute to CFEOM1 pathogenesis by altering axonal development.
Model-based Bayesian inference from high-content data obtained on live specimens is a burgeoning field with demonstrated applications to neuroscience. In parallel, computer vision methods for ...extracting the calcium signaling information from imaging data have advanced in application to neuronal physiology. Here, we are describing in detail a method we have recently developed to study calcium dynamics in astrocytes, which combines computer vision with model-based Bayesian learning to deduce the most likely molecular kinetic parameters underlying the observed calcium activity. As reported in the companion experimental study, this method allowed us to identify the key molecular changes downstream of a multi-gene deletion modeling the human 22q11.2 deletion syndrome, the most common human microdeletion and the genetic factor with the highest penetrance for schizophrenia.•Methodological details are laid out, from our imaging approach to our adaptation of the VBA-CaBBI algorithm previously developed primarily for brain functional imaging data.•The analytical pipeline is suited for further applications to glial cells and adaptable to other cell types exhibiting complexcalcium dynamics.
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Prostate cancer is a widespread malignancy characterized by a comparative ease of primary diagnosis and difficulty in choosing the individualized course of treatment. Management of prostate cancer ...would benefit from a clearer understanding of the molecular mechanisms behind the transition to the lethal, late-stage forms of the disease, which could potentially yield new biomarkers for differential prognosis and treatment prioritization in addition to possible new therapeutic targets. Epidemiological research has uncovered a significant correlation of prostate cancer incidence and progression with the intake (and often co-intake) of fatty acids and calcium. Additionally, there is evidence of the impact of these nutrients on intracellular signaling, including the mechanisms mediated by the calcium ion as a second messenger. The present review surveys the recent literature on the molecular mechanisms associated with the critical steps in the prostate cancer progression, with special attention paid to the regulation of these processes by fatty acids and calcium homeostasis. Testable hypotheses are put forward that integrate some of the recent results in a more unified picture of these phenomena at the interface of cell signaling and metabolism.
During metastasis, tumor cells migrate out of their original tissue to invade other organs. Secretion of exosomes and metalloproteases is essential for extracellular matrix remodeling, enabling ...migration through tissue barriers. Metastatic prostate cancer is differentiated by expression of the rare isoform A of the molecular motor myosin IC, however the function of this isoform remained unknown. Here we show that it contributes causatively to the invasive motility of prostate cancer cells. We found that the isoform associates with metalloprotease-containing exosomes and stimulates their secretion. While the data show that myosin IC is involved in prostate cancer cell migration, migration outside extracellular matrix in vitro proves little affected specifically by isoform A. Nevertheless, this isoform stimulates invasion through extracellular matrix, pointing to a critical role in secretion. Both the secretion and invasion depend on the integrity of the motor and lipid-binding domains of the protein. Our results demonstrate how myosin IC isoform A is likely to function in metastasis, driving secretion of exosomes that enable invasion of prostate cancer cells across extracellular matrix barriers. The new data identify a molecule suitable for a mechanistically grounded development into a marker and target for prognosis, detection, and treatment of invasive prostate cancer.
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