Primary cilia: Cell and molecular mechanosensors directing whole tissue function.

Primary cilia are immotile, microtubule-based organelles extending from the surface of nearly every mammalian cell. Mechanical stimulation causes deflection of the primary cilium, initiating downstream signaling cascades to the rest of the cell. The cilium forms a unique subcellular microdomain, and defects in ciliary protein composition or physical structure have been associated with a myriad of human pathologies. In this review, we discuss the importance of ciliary mechanotransduction at the cell and tissue level, and how furthering our molecular understanding of primary cilia mechanobiology may lead to therapeutic strategies to treat human diseases.

Adenylyl cyclase 6 mediates loading-induced bone adaptation in vivo.

Primary cilia are single, nonmotile, antenna-like structures extending from the apical membrane of most mammalian cells. They may mediate mechanotransduction, the conversion of external mechanical stimuli into biochemical intracellular signals. Previously we demonstrated that adenylyl cyclase 6 (AC6), a membrane-bound enzyme enriched in primary cilia of MLO-Y4 osteocyte-like cells, may play a role in a primary cilium-dependent mechanism of osteocyte mechanotransduction in vitro. In this study, we determined whether AC6 deletion impairs loading-induced bone formation in vivo. Skeletally mature mice with a global knockout of AC6 exhibited normal bone morphology and responded to osteogenic chemical stimuli similar to wild-type mice. Following ulnar loading over 3 consecutive days, bone formation parameters were assessed using dynamic histomorphometry. Mice lacking AC6 formed significantly less bone than control animals (41% lower bone formation rate). Furthermore, there was an attenuated flow-induced increase in COX-2 mRNA expression levels in primary bone cells isolated from AC6 knockout mice compared to controls (1.3±0.1- vs. 2.6±0.2-fold increase). Collectively, these data indicate that AC6 plays a role in loading-induced bone adaptation, and these findings are consistent with our previous studies implicating primary cilia and AC6 in a novel mechanism of osteocyte mechanotransduction.

Correction: Of herds and societies-Seasonal aspects of Vinca culture herding and land use practices revealed using sequential stable isotope analysis of animal teeth.

[This corrects the article DOI: 10.1371/journal.pone.0258230.].

Spectral Flow Cytometry Methods and Pipelines for Comprehensive Immunoprofiling of Human Peripheral Blood and Bone Marrow.

Profiling hematopoietic and immune cells provides important information about disease risk, disease status, and therapeutic responses. Spectral flow cytometry enables high-dimensional single-cell evaluation of large cohorts in a high-throughput manner. Here, we designed, optimized, and implemented new methods for deep immunophenotyping of human peripheral blood and bone marrow by spectral flow cytometry. Two blood antibody panels capture 48 cell-surface markers to assess more than 58 cell phenotypes, including subsets of T cells, B cells, monocytes, natural killer (NK) cells, and dendritic cells, and their respective markers of exhaustion, activation, and differentiation in less than 2 mL of blood. A bone marrow antibody panel captures 32 markers for 35 cell phenotypes, including stem/progenitor populations, T-cell subsets, dendritic cells, NK cells, and myeloid cells in a single tube. We adapted and developed innovative flow cytometric analysis algorithms, originally developed for single-cell genomics, to improve data integration and visualization. We also highlight technical considerations for users to ensure data fidelity. Our protocol and analysis pipeline accurately identifies rare cell types, discerns differences in cell abundance and phenotype across donors, and shows concordant immune landscape trends in patients with known hematologic malignancy. SIGNIFICANCE: This study introduces optimized methods and analysis algorithms that enhance capabilities in comprehensive immunophenotyping of human blood and bone marrow using spectral flow cytometry. This approach facilitates detection of rare cell types, enables measurement of cell variations across donors, and provides proof-of-concept in identifying known hematologic malignancies. By unlocking complexities of hematopoietic and immune landscapes at the single-cell level, this advancement holds potential for understanding disease states and therapeutic responses.

A community of practice approach to the management of metal resources, metalworking and hoarding in Bronze Age societies.

The burial of metals in hoards is a trademark phenomenon of prehistoric Europe that may be counterintuitive to perceptions of value nowadays. For the first time here, we establish detailed biographies of a large corpus of hoarded metal objects, providing new insights into how societies in the second millennium BC engaged with their convertible material wealth. We move beyond previous research on prehistoric hoarding commonly focussing on separate questions such as what was placed in hoards, who selected the objects, what were the origins of materials, and where and when they were buried. Analysing ca. 200 metal tools and weapons, we use data reduction methods to define technological pathways in the long biographies of hoarded objects extending across the sourcing of materials, production, use, decommissioning, and deposition in the Carpathian Basin. We show how the differential treatment of materials and objects was strongly biased by social decisions across artefact types. We identify shared, standardised signature treatments that crossed over social-spatial boundaries. Our findings bring new insights on the interface between communal and elite wealth management at the intersection of technological reasoning and cultural beliefs in prehistoric communities.

Fenoldopam Sensitizes Primary Cilia-Mediated Mechanosensing to Promote Osteogenic Intercellular Signaling and Whole Bone Adaptation.

Bone cells actively respond to mechanical stimuli to direct bone formation, yet there is no current treatment strategy for conditions of low bone mass and osteoporosis designed to target the inherent mechanosensitivity of bone. Our group has previously identified the primary cilium as a critical mechanosensor within bone, and that pharmacologically targeting the primary cilium with fenoldopam can enhance osteocyte mechanosensitivity. Here, we demonstrate that potentiating osteocyte mechanosensing with fenoldopam in vitro promotes pro-osteogenic paracrine signaling to osteoblasts. Conversely, impairing primary cilia formation and the function of key ciliary mechanotransduction proteins attenuates this intercellular signaling cascade. We then utilize an in vivo model of load-induced bone formation to demonstrate that fenoldopam treatment sensitizes bones of both healthy and osteoporotic mice to mechanical stimulation. Furthermore, we show minimal adverse effects of this treatment and demonstrate that prolonged treatment biases trabecular bone adaptation. This work is the first to examine the efficacy of targeting primary cilia-mediated mechanosensing to enhance bone formation in osteoporotic animals. © 2022 American Society for Bone and Mineral Research (ASBMR).

Clonal barcoding with qPCR detection enables live cell functional analyses for cancer research.

Single-cell analysis methods are valuable tools; however, current approaches do not easily enable live cell retrieval. That is a particular issue when further study of cells that were eliminated during experimentation could provide critical information. We report a clonal molecular barcoding method, called SunCatcher, that enables longitudinal tracking and live cell functional analysis. From complex cell populations, we generate single cell-derived clonal populations, infect each with a unique molecular barcode, and retain stocks of individual barcoded clones (BCs). We develop quantitative PCR-based and next-generation sequencing methods that we employ to identify and quantify BCs in vitro and in vivo. We apply SunCatcher to various breast cancer cell lines and combine respective BCs to create versions of the original cell lines. While the heterogeneous BC pools reproduce their original parental cell line proliferation and tumor progression rates, individual BCs are phenotypically and functionally diverse. Early spontaneous metastases can also be identified and quantified. SunCatcher thus provides a rapid and sensitive approach for studying live single-cell clones and clonal evolution, and performing functional analyses.

Expanding roles for AMP-activated protein kinase in neuronal survival and autophagy.

AMP-activated protein kinase (AMPK) is an evolutionarily conserved cellular switch that activates catabolic pathways and turns off anabolic processes. In this way, AMPK activation can restore the perturbation of cellular energy levels. In physiological situations, AMPK senses energy deficiency (in the form of an increased AMP/ATP ratio), but it is also activated by metabolic insults, such as glucose or oxygen deprivation. Metformin, one of the most widely prescribed anti-diabetic drugs, exerts its actions by AMPK activation. However, while the functions of AMPK as a metabolic regulator are fairly well understood, its actions in neuronal cells only recently gained attention. This review will discuss newly emerged functions of AMPK in neuroprotection and neurodegeneration. Additionally, recent views on the role of AMPK in autophagy, an important catabolic process that is also involved in neurodegeneration and cancer, will be highlighted.

Of herds and societies-Seasonal aspects of Vinca culture herding and land use practices revealed using sequential stable isotope analysis of animal teeth.

Late Neolithic Vinca communities, spread over much of central and northern Balkans during the late sixth to mid-fifth millennium BC and characterised by unusually large and densely population centres, would have required highly organised food production systems. Zooarchaeological analysis indicates that domesticate livestock were herded, but little is known about the seasonal husbandry practices that helped ensure a steady supply of animal products to Vinca farming communities. Here, we present new stable carbon (δ13C) and oxygen (δ18O) isotopic measurements of incremental bioapatite samples from the teeth of domesticated livestock and wild herbivore teeth from two late Neolithic Vinca culture sites: Vinca-Belo brdo and Stubline (Serbia). Our results show a low variation overall within sheep and goats in terms of pasture type that may have been composed of seasonal halophyte plant communities, which have higher δ13C values due to the saline rich growing environments. Cattle feeding strategies were more variable and provided with supplementary forage, such as cut branches or leafy hay, during winter. The sharp distinction in the management of cattle and sheep/goat may be associated with the development of herding strategies that sought to balance livestock feeding behaviours with available forage or, more provocatively, the emergence of household-based control over cattle-an animal that held a central economic and symbolic role in Vinca societies.

Drosophila alicorn is a neuronal maintenance factor protecting against activity-induced retinal degeneration.

Exploring mechanisms that govern neuronal responses to metabolic stress is essential for the development of therapeutic strategies aimed at treatment of neuronal injury and disease. AMP-activated protein kinase (AMPK) is a key enzyme regulating cellular energy homeostasis that responds to changes in cellular energy levels by promoting energy-restorative and inhibiting energy-consumptive processes. Recent studies have suggested that AMPK might have a neuroprotective function. However, the existing evidence is contradictory and almost exclusively derived from in vitro studies based on drug treatments and metabolic stress models. To tackle these issues in vivo, we used the Drosophila visual system. In this report, we describe a novel Drosophila mutant, alicorn (alc), encoding the single beta regulatory subunit of AMPK. Loss of alc using the eyFlp system causes severe early-onset progressive nonapoptotic neurodegeneration in the retina, the optic lobe, and the antennae, as well as behavioral and neurophysiological defects. Retinal degeneration occurs immediately after normal neuronal differentiation, can be enhanced by exposure to light, and can be prevented by blocking photoreceptor excitation. Furthermore, AMPK is required for proper viability of differentiated photoreceptors by mechanisms unrelated to polarity events that AMPK controls in epithelial tissues. In conclusion, AMPK does not affect photoreceptor development but is crucial to maintaining integrity of mature neurons under conditions of increased activity and provides protection from excitotoxicity.

AMP-activated protein kinase (AMPK) molecular crossroad for metabolic control and survival of neurons.

AMP-activated protein kinase (AMPK) constitutes a molecular hub for cellular metabolic control, common to all eukaryotic cells. Numerous reports have established how AMPK responds to changes in the AMP:ATP ratio as a measure of cellular energy levels. In this way, it integrates control over a number of metabolic enzymes and adapts cellular processes to the current energy status in various cell types, such as muscle and liver cells. The role of AMPK in the development, function, and maintenance of the nervous system, on the other hand, has only recently gained attention. Neurons, while highly metabolically active, have poor capacity for nutrient storage and are thus sensitive to energy fluctuations. Recent reports demonstrate that AMPK may have neuroprotective properties and is activated in neurons by resveratrol but also by metabolic stress in the form of ischemia/hypoxia and glucose deprivation. Novel studies on AMPK also implicate neuronal activity as a critical factor in neurodegeneration. Here we discuss the latest advances in the knowledge of AMPK's role in the metabolic control and survival of excitable cells.

An appetite for destruction: from self-eating to cell cannibalism as a neuronal survival strategy.

Autophagy plays an important role in cellular survival by resupplying cells with nutrients during starvation or by clearing misfolded proteins and damaged organelles and thereby preventing degenerative diseases. Conversely, the autophagic process is also recognized as a cellular death mechanism. The circumstances that determine whether autophagy has a beneficial or a detrimental role in cellular survival are currently unclear. We recently showed that autophagy induction is detrimental in neurons that lack a functional AMPK enzyme (AMP-activated protein kinase) and that suffer from severe metabolic stress. We further demonstrated that autophagy and AMPK are interconnected in a negative feedback loop that prevents excessive and destructive stimulation of the autophagic process. Finally, we uncovered a new survival mechanism in AMPK-deficient neurons--cell cannibalism.