In the last decade, we witnessed discoveries that established Zn
as a second major signalling metal ion in the transmission of information within cells and in communication between cells. Together ...with Ca
and Mg
, Zn
covers biological regulation with redox-inert metal ions over many orders of magnitude in concentrations. The regulatory functions of zinc ions, together with their functions as a cofactor in about three thousand zinc metalloproteins, impact virtually all aspects of cell biology. This article attempts to define the regulatory functions of zinc ions, and focuses on the nature of zinc signals and zinc signalling in pathways where zinc ions are either extracellular stimuli or intracellular messengers. These pathways interact with Ca
, redox, and phosphorylation signalling. The regulatory functions of zinc require a complex system of precise homeostatic control for transients, subcellular distribution and traffic, organellar homeostasis, and vesicular storage and exocytosis of zinc ions.
Wnt proteins are secreted glycoproteins that regulate multiple processes crucial to the development and tissue homeostasis of multicellular organisms, including tissue patterning, proliferation, cell ...fate specification, cell polarity and migration. To elicit these effects, Wnts act as autocrine as well as paracrine signalling molecules between Wnt-producing and Wnt-receiving cells. More than 40 years after the discovery of the Wg/Wnt pathway, it is still unclear how they are transported to fulfil their paracrine signalling functions. Several mechanisms have been proposed to mediate intercellular Wnt transport, including Wnt-binding proteins, lipoproteins, exosomes and cytonemes. In this Review, we describe the evidence for each proposed mechanism, and discuss how they may contribute to Wnt dispersal in tissue-specific and context-dependent manners, to regulate embryonic development precisely and maintain the internal steady state within a defined tissue.
Atherosclerosis, the major cause of myocardial infarction and stroke, results from converging inflammatory, metabolic, and biomechanical factors. Arterial lesions form at sites of low and disturbed ...blood flow but are suppressed by high laminar shear stress (LSS) mainly via transcriptional induction of the anti-inflammatory transcription factor, Kruppel-like factor 2 (Klf2). We therefore performed a whole genome CRISPR-Cas9 screen to identify genes required for LSS induction of Klf2. Subsequent mechanistic investigation revealed that LSS induces Klf2 via activation of both a MEKK2/3-MEK5-ERK5 kinase module and mitochondrial metabolism. Mitochondrial calcium and ROS signaling regulate assembly of a mitophagy- and p62-dependent scaffolding complex that amplifies MEKK-MEK5-ERK5 signaling. Blocking the mitochondrial pathway in vivo reduces expression of KLF2-dependent genes such as eNOS and inhibits vascular remodeling. Failure to activate the mitochondrial pathway limits Klf2 expression in regions of disturbed flow. This work thus defines a connection between metabolism and vascular inflammation that provides a new framework for understanding and developing treatments for vascular disease.
•PRL activity was regulated by the circadian rhythm.•PRL-induced signaling was significantly decreased in CLOCK−/− mice.•SOCS was up-regulated in CLOCK−/− mice.
The circadian molecular Clock is an ...internal time-keeping system, which regulates various physiological processes. The circadian Clock may be involved in all biological processes. The circadian Clock is closely related to prolactin’s activities. However, until now, the effect of circadian Clock dysregulation on PRL’s bioactivities remains unclear. Clock protein is an essential component in circadian Clock and necessary for Clock function. Therefore, Clock gene knockout mice (CLOCK −/− mice) was used to explore the effect of circadian Clock dysfunction on PRL’s activities. The in vitro and in vivo experimental results showed that PRLR-mediated signaling was significantly down-regulated. PRL-induced JAK2-STAT5 signaling in Clock-/- mice was significantly decreased compared to control mice in vivo. In vitro, PRL/PRLR-mediated signaling in mammary epithelial cell that Clock was knocked down by siRNA was significantly down-regulated compared to control cells. Mechanistically, the expression levels of negative regulatory molecule (the suppressor of cytokine signaling (SOCS) was upregulated in vitro and in vivo, which may be one of the factors that causes the PRL-signaling downregulation. Taken together, the current work indicates that the circadian Clock affects the PRL’s activities. This finding lays the foundation for studying the relationship between the circadian Clock and PRL’s biological activities.
Intracellular calcium (Ca2+) signals are key regulators of multiple cellular functions, both healthy and physiopathological. It is therefore unsurprising that several cancers present a strong Ca2+ ...homeostasis deregulation. Among the various hallmarks of cancer disease, a particular role is played by metastasis, which has a critical impact on cancer patients’ outcome. Importantly, Ca2+ signalling has been reported to control multiple aspects of the adaptive metastatic cancer cell behaviour, including epithelial–mesenchymal transition, cell migration, local invasion and induction of angiogenesis (see Figure). In this context Ca2+ signalling is considered to be a substantial intracellular tool that regulates the dynamicity and complexity of the metastatic cascade. In the present study we review the spatial and temporal organization of Ca2+ fluxes, as well as the molecular mechanisms involved in metastasis, analysing the key steps which regulate initial tumour spread.
Model of the specific patterns of Ca2+ signals that are associated with different steps of cancer progression. It is important to note that most of the findings on Ca2+ signalling have been generated in vitro. Therefore, it is possible that in tissues, Ca2+ signals do not simply follow the same patterns.
The initiation of an intestinal tumour is a probabilistic process that depends on the competition between mutant and normal epithelial stem cells in crypts
. Intestinal stem cells are closely ...associated with a diverse but poorly characterized network of mesenchymal cell types
. However, whether the physiological mesenchymal microenvironment of mutant stem cells affects tumour initiation remains unknown. Here we provide in vivo evidence that the mesenchymal niche controls tumour initiation in trans. By characterizing the heterogeneity of the intestinal mesenchyme using single-cell RNA-sequencing analysis, we identified a population of rare pericryptal Ptgs2-expressing fibroblasts that constitutively process arachidonic acid into highly labile prostaglandin E
(PGE
). Specific ablation of Ptgs2 in fibroblasts was sufficient to prevent tumour initiation in two different models of sporadic, autochthonous tumorigenesis. Mechanistically, single-cell RNA-sequencing analyses of a mesenchymal niche model showed that fibroblast-derived PGE
drives the expansion οf a population of Sca-1
reserve-like stem cells. These express a strong regenerative/tumorigenic program, driven by the Hippo pathway effector Yap. In vivo, Yap is indispensable for Sca-1
cell expansion and early tumour initiation and displays a nuclear localization in both mouse and human adenomas. Using organoid experiments, we identified a molecular mechanism whereby PGE
promotes Yap dephosphorylation, nuclear translocation and transcriptional activity by signalling through the receptor Ptger4. Epithelial-specific ablation of Ptger4 misdirected the regenerative reprogramming of stem cells and prevented Sca-1
cell expansion and sporadic tumour initiation in mutant mice, thereby demonstrating the robust paracrine control of tumour-initiating stem cells by PGE
-Ptger4. Analyses of patient-derived organoids established that PGE
-PTGER4 also regulates stem-cell function in humans. Our study demonstrates that initiation of colorectal cancer is orchestrated by the mesenchymal niche and reveals a mechanism by which rare pericryptal Ptgs2-expressing fibroblasts exert paracrine control over tumour-initiating stem cells via the druggable PGE
-Ptger4-Yap signalling axis.
Piezo1 belongs to mechano‐activatable cation channels serving as biological force sensors. However, the molecular events downstream of Piezo1 activation remain unclear. In this study, we used ...biosensors based on fluorescence resonance energy transfer (FRET) to investigate the dynamic modes of Piezo1‐mediated signaling and revealed a bimodal pattern of Piezo1‐induced intracellular calcium signaling. Laser‐induced shockwaves (LIS) and its associated shear stress can mechanically activate Piezo1 to induce transient intracellular calcium (Cai) elevation, accompanied by an increase in FAK activity. Interestingly, multiple pulses of shockwave stimulation caused a more sustained calcium increase and a decrease in FAK activity. Similarly, tuning the degree of Piezo1 activation by titrating either the dosage of Piezo1 ligand Yoda1 or the expression level of Piezo1 produced a similar bimodal pattern of FAK responses. Further investigations revealed that SHP2 serves as an intermediate regulator mediating this bimodal pattern in Piezo1 sensing and signaling. These results suggest that the degrees of Piezo1 activation induced by both mechanical LIS and chemical ligand stimulation may determine downstream signaling characteristics.
Synopsis
How activation of the mechano‐sensitive Piezo1 cation channel transmits signals remains incompletely understood. Here, the degree of Piezo1 activation induced by mechanical force or chemical ligand stimulation is found to determine downstream signaling characteristics.
FRET imaging in live cells monitors the effects of laser‐induced shockwaves (LIS) and their associated shear stress, and of Piezo1 stimulation by its chemical ligand Yoda1.
Mechanical or chemical activation of Piezo1 induces transient intracellular calcium elevation, accompanied by an increase in FAK activity.
Multiple pulses of shockwave stimulation cause a more sustained calcium increase and a decrease in FAK activity.
SHP2 can serve as an intermediate regulator mediating this bimodal pattern in Piezo1 sensing and signaling.
Combination of mechanical laser‐induced shockwave or chemical ligand Yoda1 stimulation and FRET imaging in live cells reveals that transient versus sustained calcium influx through mechano‐activatable channels has opposite effects on FAK kinase activity.
Nutrient signalling integrates and coordinates gene expression, metabolism and growth. However, its primary molecular mechanisms remain incompletely understood in plants and animals. Here we report ...unique Ca
signalling triggered by nitrate with live imaging of an ultrasensitive biosensor in Arabidopsis leaves and roots. A nitrate-sensitized and targeted functional genomic screen identifies subgroup III Ca
-sensor protein kinases (CPKs) as master regulators that orchestrate primary nitrate responses. A chemical switch with the engineered mutant CPK10(M141G) circumvents embryo lethality and enables conditional analyses of cpk10 cpk30 cpk32 triple mutants to define comprehensive nitrate-associated regulatory and developmental programs. Nitrate-coupled CPK signalling phosphorylates conserved NIN-LIKE PROTEIN (NLP) transcription factors to specify the reprogramming of gene sets for downstream transcription factors, transporters, nitrogen assimilation, carbon/nitrogen metabolism, redox, signalling, hormones and proliferation. Conditional cpk10 cpk30 cpk32 and nlp7 mutants similarly impair nitrate-stimulated system-wide shoot growth and root establishment. The nutrient-coupled Ca
signalling network integrates transcriptome and cellular metabolism with shoot-root coordination and developmental plasticity in shaping organ biomass and architecture.
The beating heart possesses the intrinsic ability to adapt cardiac output to changes in mechanical load. The century-old Frank-Starling law and Anrep effect have documented that stretching the heart ...during diastolic filling increases its contractile force. However, the molecular mechanotransduction mechanism and its impact on cardiac health and disease remain elusive. Here we show that the mechanically activated Piezo1 channel converts mechanical stretch of cardiomyocytes into Ca
and reactive oxygen species (ROS) signaling, which critically determines the mechanical activity of the heart. Either cardiac-specific knockout or overexpression of Piezo1 in mice results in defective Ca
and ROS signaling and the development of cardiomyopathy, demonstrating a homeostatic role of Piezo1. Piezo1 is pathologically upregulated in both mouse and human diseased hearts via an autonomic response of cardiomyocytes. Thus, Piezo1 serves as a key cardiac mechanotransducer for initiating mechano-chemo transduction and consequently maintaining normal heart function, and might represent a novel therapeutic target for treating human heart diseases.
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