RESUMEN
The mechanism that initiates autophagosome formation on the ER in multicellular organisms is elusive. Here, we showed that autophagy stimuli trigger Ca2+ transients on the outer surface of the ER membrane, whose amplitude, frequency, and duration are controlled by the metazoan-specific ER transmembrane autophagy protein EPG-4/EI24. Persistent Ca2+ transients/oscillations on the cytosolic ER surface in EI24-depleted cells cause accumulation of FIP200 autophagosome initiation complexes on the ER. This defect is suppressed by attenuating ER Ca2+ transients. Multi-modal SIM analysis revealed that Ca2+ transients on the ER trigger the formation of dynamic and fusion-prone liquid-like FIP200 puncta. Starvation-induced Ca2+ transients on lysosomes also induce FIP200 puncta that further move to the ER. Multiple FIP200 puncta on the ER, whose association depends on the ER proteins VAPA/B and ATL2/3, assemble into autophagosome formation sites. Thus, Ca2+ transients are crucial for triggering phase separation of FIP200 to specify autophagosome initiation sites in metazoans.
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Autofagosomas , Calcio , Animales , Autofagosomas/metabolismo , Calcio/metabolismo , Retículo Endoplásmico/metabolismo , Proteínas Relacionadas con la Autofagia/metabolismo , Autofagia , Proteínas de Ciclo Celular/metabolismoRESUMEN
Interferons (IFNs) induce an antimicrobial state, protecting tissues from infection. Many viruses inhibit IFN signaling, but whether bacterial pathogens evade IFN responses remains unclear. Here, we demonstrate that the Shigella OspC family of type-III-secreted effectors blocks IFN signaling independently of its cell death inhibitory activity. Rather, IFN inhibition was mediated by the binding of OspC1 and OspC3 to the Ca2+ sensor calmodulin (CaM), blocking CaM kinase II and downstream JAK/STAT signaling. The growth of Shigella lacking OspC1 and OspC3 was attenuated in epithelial cells and in a murine model of infection. This phenotype was rescued in both models by the depletion of IFN receptors. OspC homologs conserved in additional pathogens not only bound CaM but also inhibited IFN, suggesting a widespread virulence strategy. These findings reveal a conserved but previously undescribed molecular mechanism of IFN inhibition and demonstrate the critical role of Ca2+ and IFN targeting in bacterial pathogenesis.
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Interferones , Factores de Virulencia , Animales , Antivirales , Señalización del Calcio , Células Epiteliales/metabolismo , Interferones/metabolismo , Ratones , Factores de Virulencia/metabolismoRESUMEN
Plant immunity is activated upon pathogen perception and often affects growth and yield when it is constitutively active. How plants fine-tune immune homeostasis in their natural habitats remains elusive. Here, we discover a conserved immune suppression network in cereals that orchestrates immune homeostasis, centering on a Ca2+-sensor, RESISTANCE OF RICE TO DISEASES1 (ROD1). ROD1 promotes reactive oxygen species (ROS) scavenging by stimulating catalase activity, and its protein stability is regulated by ubiquitination. ROD1 disruption confers resistance to multiple pathogens, whereas a natural ROD1 allele prevalent in indica rice with agroecology-specific distribution enhances resistance without yield penalty. The fungal effector AvrPiz-t structurally mimics ROD1 and activates the same ROS-scavenging cascade to suppress host immunity and promote virulence. We thus reveal a molecular framework adopted by both host and pathogen that integrates Ca2+ sensing and ROS homeostasis to suppress plant immunity, suggesting a principle for breeding disease-resistant, high-yield crops.
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Calcio/metabolismo , Depuradores de Radicales Libres/metabolismo , Proteínas Fúngicas/metabolismo , Oryza/inmunología , Inmunidad de la Planta , Proteínas de Plantas/metabolismo , Especies Reactivas de Oxígeno/metabolismo , Sistemas CRISPR-Cas/genética , Membrana Celular/metabolismo , Resistencia a la Enfermedad/genética , Modelos Biológicos , Oryza/genética , Enfermedades de las Plantas/inmunología , Proteínas de Plantas/genética , Unión Proteica , Estabilidad Proteica , Reproducción , Especificidad de la Especie , Ubiquitina-Proteína Ligasas/metabolismo , Ubiquitinación , Zea mays/inmunologíaRESUMEN
Neural stem cells (NSCs) in the adult brain transit from the quiescent state to proliferation to produce new neurons. The mechanisms regulating this transition in freely behaving animals are, however, poorly understood. We customized in vivo imaging protocols to follow NSCs for several days up to months, observing their activation kinetics in freely behaving mice. Strikingly, NSC division is more frequent during daylight and is inhibited by darkness-induced melatonin signaling. The inhibition of melatonin receptors affected intracellular Ca2+ dynamics and promoted NSC activation. We further discovered a Ca2+ signature of quiescent versus activated NSCs and showed that several microenvironmental signals converge on intracellular Ca2+ pathways to regulate NSC quiescence and activation. In vivo NSC-specific optogenetic modulation of Ca2+ fluxes to mimic quiescent-state-like Ca2+ dynamics in freely behaving mice blocked NSC activation and maintained their quiescence, pointing to the regulatory mechanisms mediating NSC activation in freely behaving animals.
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Células Madre Adultas/metabolismo , Calcio/metabolismo , Ritmo Circadiano , Espacio Intracelular/metabolismo , Células-Madre Neurales/metabolismo , Células Madre Adultas/citología , Células Madre Adultas/efectos de los fármacos , Animales , Astrocitos/efectos de los fármacos , Astrocitos/metabolismo , Conducta Animal/efectos de los fármacos , División Celular/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Ritmo Circadiano/efectos de los fármacos , Citosol/metabolismo , Factor de Crecimiento Epidérmico/farmacología , Receptores de Inositol 1,4,5-Trifosfato/metabolismo , Melatonina/metabolismo , Ratones , Células-Madre Neurales/citología , Células-Madre Neurales/efectos de los fármacos , Optogenética , Transducción de Señal/efectos de los fármacos , Triptaminas/farmacologíaRESUMEN
Single-cell transcriptomics has been widely applied to classify neurons in the mammalian brain, while systems neuroscience has historically analyzed the encoding properties of cortical neurons without considering cell types. Here we examine how specific transcriptomic types of mouse prefrontal cortex (PFC) projection neurons relate to axonal projections and encoding properties across multiple cognitive tasks. We found that most types projected to multiple targets, and most targets received projections from multiple types, except PFCâPAG (periaqueductal gray). By comparing Ca2+ activity of the molecularly homogeneous PFCâPAG type against two heterogeneous classes in several two-alternative choice tasks in freely moving mice, we found that all task-related signals assayed were qualitatively present in all examined classes. However, PAG-projecting neurons most potently encoded choice in cued tasks, whereas contralateral PFC-projecting neurons most potently encoded reward context in an uncued task. Thus, task signals are organized redundantly, but with clear quantitative biases across cells of specific molecular-anatomical characteristics.
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Cognición/fisiología , Neuronas/fisiología , Corteza Prefrontal/fisiología , Análisis y Desempeño de Tareas , Animales , Calcio/metabolismo , Conducta de Elección , Señales (Psicología) , Imagenología Tridimensional , Integrasas/metabolismo , Ratones Endogámicos C57BL , Odorantes , Optogenética , Sustancia Gris Periacueductal/fisiología , Recompensa , Análisis de la Célula Individual , Transcriptoma/genéticaRESUMEN
P-type ATPases are found in all kingdoms of life and constitute a wide range of cation transporters, primarily for H+, Na+, K+, Ca2+, and transition metal ions such as Cu(I), Zn(II), and Cd(II). They have been studied through a wide range of techniques, and research has gained very significant insight on their transport mechanism and regulation. Here, we review the structure, function, and dynamics of P2-ATPases including Ca2+-ATPases and Na,K-ATPase. We highlight mechanisms of functional transitions that are associated with ion exchange on either side of the membrane and how the functional cycle is regulated by interaction partners, autoregulatory domains, and off-cycle states. Finally, we discuss future perspectives based on emerging techniques and insights.
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Adenosina Trifosfato/química , ATPasas Transportadoras de Cobre/química , ATPasa Intercambiadora de Hidrógeno-Potásio/química , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/química , ATPasa Intercambiadora de Sodio-Potasio/química , Adenosina Trifosfato/metabolismo , Animales , Sitios de Unión , Cationes Bivalentes , Cationes Monovalentes , ATPasas Transportadoras de Cobre/genética , ATPasas Transportadoras de Cobre/metabolismo , ATPasa Intercambiadora de Hidrógeno-Potásio/genética , ATPasa Intercambiadora de Hidrógeno-Potásio/metabolismo , Humanos , Transporte Iónico , Modelos Moleculares , Unión Proteica , Dominios y Motivos de Interacción de Proteínas , Estructura Secundaria de Proteína , Protones , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/genética , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/metabolismo , Imagen Individual de Molécula , ATPasa Intercambiadora de Sodio-Potasio/genética , ATPasa Intercambiadora de Sodio-Potasio/metabolismo , Especificidad por SustratoRESUMEN
Cognitive faculties such as imagination, planning, and decision-making entail the ability to represent hypothetical experience. Crucially, animal behavior in natural settings implies that the brain can represent hypothetical future experience not only quickly but also constantly over time, as external events continually unfold. To determine how this is possible, we recorded neural activity in the hippocampus of rats navigating a maze with multiple spatial paths. We found neural activity encoding two possible future scenarios (two upcoming maze paths) in constant alternation at 8 Hz: one scenario per â¼125-ms cycle. Further, we found that the underlying dynamics of cycling (both inter- and intra-cycle dynamics) generalized across qualitatively different representational correlates (location and direction). Notably, cycling occurred across moving behaviors, including during running. These findings identify a general dynamic process capable of quickly and continually representing hypothetical experience, including that of multiple possible futures.
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Conducta Animal/fisiología , Cognición/fisiología , Toma de Decisiones/fisiología , Hipocampo/fisiología , Potenciales de Acción/fisiología , Animales , Locomoción/fisiología , Masculino , Aprendizaje por Laberinto/fisiología , Red Nerviosa/fisiología , Neuronas/fisiología , Ratas , Ratas Long-Evans , Ritmo Teta/fisiologíaRESUMEN
Varying pH of luminal fluid along the female reproductive tract is a physiological cue that modulates sperm motility. CatSper is a sperm-specific, pH-sensitive calcium channel essential for hyperactivated motility and male fertility. Multi-subunit CatSper channel complexes organize linear Ca2+ signaling nanodomains along the sperm tail. Here, we identify EF-hand calcium-binding domain-containing protein 9 (EFCAB9) as a bifunctional, cytoplasmic machine modulating the channel activity and the domain organization of CatSper. Knockout mice studies demonstrate that EFCAB9, in complex with the CatSper subunit, CATSPERζ, is essential for pH-dependent and Ca2+-sensitive activation of the CatSper channel. In the absence of EFCAB9, sperm motility and fertility is compromised, and the linear arrangement of the Ca2+ signaling domains is disrupted. EFCAB9 interacts directly with CATSPERζ in a Ca2+-dependent manner and dissociates at elevated pH. These observations suggest that EFCAB9 is a long-sought, intracellular, pH-dependent Ca2+ sensor that triggers changes in sperm motility.
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Proteínas de Unión al Calcio/metabolismo , Motilidad Espermática/fisiología , Animales , Calcio/metabolismo , Canales de Calcio/metabolismo , Señalización del Calcio/fisiología , Proteínas de Unión al Calcio/fisiología , Línea Celular , Membrana Celular/metabolismo , Fertilidad , Células HEK293 , Humanos , Concentración de Iones de Hidrógeno , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Espermatozoides/metabolismoRESUMEN
Expansion of CAG trinucleotide repeats in ATXN1 causes spinocerebellar ataxia type 1 (SCA1), a neurodegenerative disease that impairs coordination and cognition. While ATXN1 is associated with increased Alzheimer's disease (AD) risk, CAG repeat number in AD patients is not changed. Here, we investigated the consequences of ataxin-1 loss of function and discovered that knockout of Atxn1 reduced CIC-ETV4/5-mediated inhibition of Bace1 transcription, leading to increased BACE1 levels and enhanced amyloidogenic cleavage of APP, selectively in AD-vulnerable brain regions. Elevated BACE1 expression exacerbated Aß deposition and gliosis in AD mouse models and impaired hippocampal neurogenesis and olfactory axonal targeting. In SCA1 mice, polyglutamine-expanded mutant ataxin-1 led to the increase of BACE1 post-transcriptionally, both in cerebrum and cerebellum, and caused axonal-targeting deficit and neurodegeneration in the hippocampal CA2 region. These findings suggest that loss of ataxin-1 elevates BACE1 expression and Aß pathology, rendering it a potential contributor to AD risk and pathogenesis.
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Enfermedad de Alzheimer/patología , Secretasas de la Proteína Precursora del Amiloide/metabolismo , Ataxina-1/metabolismo , Encéfalo/metabolismo , Enfermedad de Alzheimer/metabolismo , Secretasas de la Proteína Precursora del Amiloide/genética , Precursor de Proteína beta-Amiloide/metabolismo , Animales , Ataxina-1/deficiencia , Ataxina-1/genética , Encéfalo/patología , Región CA2 Hipocampal/metabolismo , Región CA2 Hipocampal/patología , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Modelos Animales de Enfermedad , Femenino , Frecuencia de los Genes , Humanos , Masculino , Ratones , Ratones Transgénicos , Neurogénesis , Proteínas Proto-Oncogénicas c-ets/genética , Proteínas Proto-Oncogénicas c-ets/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Transcripción Genética , Repeticiones de Trinucleótidos/genética , Regulación hacia ArribaRESUMEN
Calcium imaging using two-photon scanning microscopy has become an essential tool in neuroscience. However, in its typical implementation, the tradeoffs between fields of view, acquisition speeds, and depth restrictions in scattering brain tissue pose severe limitations. Here, using an integrated systems-wide optimization approach combined with multiple technical innovations, we introduce a new design paradigm for optical microscopy based on maximizing biological information while maintaining the fidelity of obtained neuron signals. Our modular design utilizes hybrid multi-photon acquisition and allows volumetric recording of neuroactivity at single-cell resolution within up to 1 × 1 × 1.22 mm volumes at up to 17 Hz in awake behaving mice. We establish the capabilities and potential of the different configurations of our imaging system at depth and across brain regions by applying it to in vivo recording of up to 12,000 neurons in mouse auditory cortex, posterior parietal cortex, and hippocampus.
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Microscopía/métodos , Imagen Molecular/métodos , Neuroimagen/métodos , Animales , Encéfalo/fisiología , Calcio/metabolismo , Femenino , Hipocampo/fisiología , Masculino , Ratones , Ratones Endogámicos C57BL , Neuronas/fisiología , Análisis de la Célula Individual/métodosRESUMEN
To decipher dynamic brain information processing, current genetically encoded calcium indicators (GECIs) are limited in single action potential (AP) detection speed, combinatorial spectral compatibility, and two-photon imaging depth. To address this, here, we rationally engineered a next-generation quadricolor GECI suite, XCaMPs. Single AP detection was achieved within 3-10 ms of spike onset, enabling measurements of fast-spike trains in parvalbumin (PV)-positive interneurons in the barrel cortex in vivo and recording three distinct (two inhibitory and one excitatory) ensembles during pre-motion activity in freely moving mice. In vivo paired recording of pre- and postsynaptic firing revealed spatiotemporal constraints of dendritic inhibition in layer 1 in vivo, between axons of somatostatin (SST)-positive interneurons and apical tufts dendrites of excitatory pyramidal neurons. Finally, non-invasive, subcortical imaging using red XCaMP-R uncovered somatosensation-evoked persistent activity in hippocampal CA1 neurons. Thus, the XCaMPs offer a critical enhancement of solution space in studies of complex neuronal circuit dynamics. VIDEO ABSTRACT.
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Potenciales de Acción/fisiología , Axones/metabolismo , Corteza Cerebral/metabolismo , Hipocampo/metabolismo , Interneuronas/metabolismo , Células Piramidales/metabolismo , Animales , Corteza Cerebral/citología , Femenino , Hipocampo/citología , Interneuronas/citología , Ratones , Ratones Transgénicos , Células Piramidales/citología , Ratas , Ratas Sprague-DawleyRESUMEN
The endoplasmic reticulum (ER) has a broad localization throughout the cell and forms direct physical contacts with all other classes of membranous organelles, including the plasma membrane (PM). A number of protein tethers that mediate these contacts have been identified, and study of these protein tethers has revealed a multiplicity of roles in cell physiology, including regulation of intracellular Ca2+ dynamics and signaling as well as control of lipid traffic and homeostasis. In this review, we discuss the cross talk between the ER and the PM mediated by direct contacts. We review factors that tether the two membranes, their properties, and their dynamics in response to the functional state of the cell. We focus in particular on the role of ER-PM contacts in nonvesicular lipid transport between the two bilayers mediated by lipid transfer proteins.
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Calcio/metabolismo , Proteínas Portadoras/metabolismo , Membrana Celular/metabolismo , Retículo Endoplásmico/metabolismo , Proteínas de la Membrana/metabolismo , Proteína ORAI1/metabolismo , Transporte Biológico , Señalización del Calcio , Proteínas Portadoras/genética , Membrana Celular/ultraestructura , Retículo Endoplásmico/ultraestructura , Células Eucariotas/metabolismo , Células Eucariotas/ultraestructura , Expresión Génica , Homeostasis , Humanos , Proteínas de la Membrana/genética , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/metabolismo , Proteína ORAI1/genética , Receptores de Esteroides/genética , Receptores de Esteroides/metabolismo , Molécula de Interacción Estromal 1/genética , Molécula de Interacción Estromal 1/metabolismo , Sinaptotagminas/genética , Sinaptotagminas/metabolismoRESUMEN
The medial amygdala (MeA) plays a critical role in processing species- and sex-specific signals that trigger social and defensive behaviors. However, the principles by which this deep brain structure encodes social information is poorly understood. We used a miniature microscope to image the Ca2+ dynamics of large neural ensembles in awake behaving mice and tracked the responses of MeA neurons over several months. These recordings revealed spatially intermingled subsets of MeA neurons with distinct temporal dynamics. The encoding of social information in the MeA differed between males and females and relied on information from both individual cells and neuronal populations. By performing long-term Ca2+ imaging across different social contexts, we found that sexual experience triggers lasting and sex-specific changes in MeA activity, which, in males, involve signaling by oxytocin. These findings reveal basic principles underlying the brain's representation of social information and its modulation by intrinsic and extrinsic factors.
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Amígdala del Cerebelo/fisiología , Neuronas/citología , Vigilia , Amígdala del Cerebelo/citología , Animales , Conducta Animal , Señales (Psicología) , Endoscopía/métodos , Femenino , Masculino , Ratones , Microscopía/métodos , Oxitocina/fisiología , Caracteres Sexuales , Conducta Sexual Animal , Conducta SocialRESUMEN
Reward-seeking behavior is fundamental to survival, but suppression of this behavior can be essential as well, even for rewards of high value. In humans and rodents, the medial prefrontal cortex (mPFC) has been implicated in suppressing reward seeking; however, despite vital significance in health and disease, the neural circuitry through which mPFC regulates reward seeking remains incompletely understood. Here, we show that a specific subset of superficial mPFC projections to a subfield of nucleus accumbens (NAc) neurons naturally encodes the decision to initiate or suppress reward seeking when faced with risk of punishment. A highly resolved subpopulation of these top-down projecting neurons, identified by 2-photon Ca2+ imaging and activity-dependent labeling to recruit the relevant neurons, was found capable of suppressing reward seeking. This natural activity-resolved mPFC-to-NAc projection displayed unique molecular-genetic and microcircuit-level features concordant with a conserved role in the regulation of reward-seeking behavior, providing cellular and anatomical identifiers of behavioral and possible therapeutic significance.
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Recompensa , Animales , Conducta Animal , Femenino , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Vías Nerviosas , Neuroimagen , Corteza Prefrontal/citología , Corteza Prefrontal/metabolismo , CastigoRESUMEN
In the last 5 years, most of the molecules that control mitochondrial Ca(2+) homeostasis have been finally identified. Mitochondrial Ca(2+) uptake is mediated by the Mitochondrial Calcium Uniporter (MCU) complex, a macromolecular structure that guarantees Ca(2+) accumulation inside mitochondrial matrix upon increases in cytosolic Ca(2+). Conversely, Ca(2+) release is under the control of the Na(+)/Ca(2+) exchanger, encoded by the NCLX gene, and of a H(+)/Ca(2+) antiporter, whose identity is still debated. The low affinity of the MCU complex, coupled to the activity of the efflux systems, protects cells from continuous futile cycles of Ca(2+) across the inner mitochondrial membrane and consequent massive energy dissipation. In this review, we discuss the basic principles that govern mitochondrial Ca(2+) homeostasis and the methods used to investigate the dynamics of Ca(2+) concentration within the organelles. We discuss the functional and structural role of the different molecules involved in mitochondrial Ca(2+) handling and their pathophysiological role.
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Canales de Calcio/metabolismo , Calcio/metabolismo , Mitocondrias/metabolismo , Intercambiador de Sodio-Calcio/metabolismo , Animales , Canales de Calcio/química , Canales de Calcio/genética , Señalización del Calcio , Regulación de la Expresión Génica , Homeostasis , Humanos , Transporte Iónico , Cinética , Mitocondrias/genética , Mitocondrias/ultraestructura , Membranas Mitocondriales/metabolismo , Membranas Mitocondriales/ultraestructura , Proteínas Mitocondriales , Modelos Moleculares , Intercambiador de Sodio-Calcio/genética , TermodinámicaRESUMEN
The gastrointestinal (GI) tract displays multiple motor patterns that move nutrients and wastes through the body. Smooth muscle cells (SMCs) provide the forces necessary for GI motility, but interstitial cells, electrically coupled to SMCs, tune SMC excitability, transduce inputs from enteric motor neurons, and generate pacemaker activity that underlies major motor patterns, such as peristalsis and segmentation. The interstitial cells regulating SMCs are interstitial cells of Cajal (ICC) and PDGF receptor (PDGFR)α+ cells. Together these cells form the SIP syncytium. ICC and PDGFRα+ cells express signature Ca2+-dependent conductances: ICC express Ca2+-activated Cl- channels, encoded by Ano1, that generate inward current, and PDGFRα+ cells express Ca2+-activated K+ channels, encoded by Kcnn3, that generate outward current. The open probabilities of interstitial cell conductances are controlled by Ca2+ release from the endoplasmic reticulum. The resulting Ca2+ transients occur spontaneously in a stochastic manner. Ca2+ transients in ICC induce spontaneous transient inward currents and spontaneous transient depolarizations (STDs). Neurotransmission increases or decreases Ca2+ transients, and the resulting depolarizing or hyperpolarizing responses conduct to other cells in the SIP syncytium. In pacemaker ICC, STDs activate voltage-dependent Ca2+ influx, which initiates a cluster of Ca2+ transients and sustains activation of ANO1 channels and depolarization during slow waves. Regulation of GI motility has traditionally been described as neurogenic and myogenic. Recent advances in understanding Ca2+ handling mechanisms in interstitial cells and how these mechanisms influence motor patterns of the GI tract suggest that the term "myogenic" should be replaced by the term "SIPgenic," as this review discusses.
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Células Intersticiales de Cajal , Humanos , Células Intersticiales de Cajal/fisiología , Receptor alfa de Factor de Crecimiento Derivado de Plaquetas , Músculo Liso/fisiología , Tracto Gastrointestinal , Intestino Delgado/fisiologíaRESUMEN
The protection of DNA replication forks under stress is essential for genome maintenance and cancer suppression. One mechanism of fork protection involves an elevation in intracellular Ca2+ ([Ca2+]i), which in turn activates CaMKK2 and AMPK to prevent uncontrolled fork processing by Exo1. How replication stress triggers [Ca2+]i elevation is unclear. Here, we report a role of cytosolic self-DNA (cytosDNA) and the ion channel TRPV2 in [Ca2+]i induction and fork protection. Replication stress leads to the generation of ssDNA and dsDNA species that, upon translocation into cytoplasm, trigger the activation of the sensor protein cGAS and the production of cGAMP. The subsequent binding of cGAMP to STING causes its dissociation from TRPV2, leading to TRPV2 derepression and Ca2+ release from the ER, which in turn activates the downstream signaling cascade to prevent fork degradation. This Ca2+-dependent genome protection pathway is also activated in response to replication stress caused by oncogene activation.
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ADN , Nucleotidiltransferasas , ADN/genética , ADN/metabolismo , Replicación del ADN , ADN de Cadena Simple , Proteínas de la Membrana , Nucleotidiltransferasas/metabolismo , Transducción de Señal/fisiología , Canales Catiónicos TRPVRESUMEN
The pulmonary circulation is a low-resistance, low-pressure, and high-compliance system that allows the lungs to receive the entire cardiac output. Pulmonary arterial pressure is a function of cardiac output and pulmonary vascular resistance, and pulmonary vascular resistance is inversely proportional to the fourth power of the intraluminal radius of the pulmonary artery. Therefore, a very small decrease of the pulmonary vascular lumen diameter results in a significant increase in pulmonary vascular resistance and pulmonary arterial pressure. Pulmonary arterial hypertension is a fatal and progressive disease with poor prognosis. Regardless of the initial pathogenic triggers, sustained pulmonary vasoconstriction, concentric vascular remodeling, occlusive intimal lesions, in situ thrombosis, and vascular wall stiffening are the major and direct causes for elevated pulmonary vascular resistance in patients with pulmonary arterial hypertension and other forms of precapillary pulmonary hypertension. In this review, we aim to discuss the basic principles and physiological mechanisms involved in the regulation of lung vascular hemodynamics and pulmonary vascular function, the changes in the pulmonary vasculature that contribute to the increased vascular resistance and arterial pressure, and the pathogenic mechanisms involved in the development and progression of pulmonary hypertension. We focus on reviewing the pathogenic roles of membrane receptors, ion channels, and intracellular Ca2+ signaling in pulmonary vascular smooth muscle cells in the development and progression of pulmonary hypertension.
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Hipertensión Pulmonar , Hipertensión Arterial Pulmonar , Humanos , Hipertensión Arterial Pulmonar/patología , Canales Iónicos , Pulmón , Vasoconstricción/fisiología , Señalización del Calcio/fisiología , Miocitos del Músculo LisoRESUMEN
Animal behavior was classically considered to be determined exclusively by neuronal activity, whereas surrounding glial cells such as astrocytes played only supportive roles. However, astrocytes are as numerous as neurons in the mammalian brain, and current findings indicate a chemically based dialog between astrocytes and neurons. Activation of astrocytes by synaptically released neurotransmitters converges on regulating intracellular Ca2+ in astrocytes, which then can regulate the efficacy of near and distant tripartite synapses at diverse timescales through gliotransmitter release. Here, we discuss recent evidence on how diverse behaviors are impacted by this dialog. These recent findings support a paradigm shift in neuroscience, in which animal behavior does not result exclusively from neuronal activity but from the coordinated activity of both astrocytes and neurons. Decoding how astrocytes and neurons interact with each other in various brain circuits will be fundamental to fully understanding how behaviors originate and become dysregulated in disease.
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Astrocitos , Transmisión Sináptica , Animales , Neuroglía , Neuronas , SinapsisRESUMEN
The emerging role of mitochondria as signaling organelles raises the question of whether individual mitochondria can initiate heterotypic communication with neighboring organelles. Using fluorescent probes targeted to the endoplasmic-reticulum-mitochondrial interface, we demonstrate that single mitochondria generate oxidative bursts, rapid redox oscillations, confined to the nanoscale environment of the interorganellar contact sites. Using probes fused to inositol 1,4,5-trisphosphate receptors (IP3Rs), we show that Ca2+ channels directly sense oxidative bursts and respond with Ca2+ transients adjacent to active mitochondria. Application of specific mitochondrial stressors or apoptotic stimuli dramatically increases the frequency and amplitude of the oxidative bursts by enhancing transient permeability transition pore openings. Conversely, blocking interface Ca2+ transport via elimination of IP3Rs or mitochondrial calcium uniporter channels suppresses ER-mitochondrial Ca2+ feedback and cell death. Thus, single mitochondria initiate local retrograde signaling by miniature oxidative bursts and, upon metabolic or apoptotic stress, may also amplify signals to the rest of the cell.