Publications by authors named "Joao Relvas"

Contrary to the adult central nervous system, the peripheral nervous system has an intrinsic ability to regenerate that relies on the expression of regeneration-associated genes, such as some kinesin family members. Kinesins contribute to nerve regeneration through the transport of specific cargo, such as proteins and membrane components, from the cell body towards the axon periphery. We show here that KIF4A, associated with neurodevelopmental disorders and previously believed to be only expressed during development, is also expressed in the adult vertebrate nervous system and up-regulated in injured peripheral nervous system cells.

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Timely differentiation and myelin formation by oligodendrocytes are essential for the physiological functioning of the central nervous system (CNS). While the Rho GTPase RhoA has been hinted as a negative regulator of myelin sheath formation, the precise in vivo mechanisms have remained elusive. Here we show that RhoA controls the timing and progression of myelination by oligodendrocytes through a fine-tuned balance between cortical tension, membrane tension and cell shape.

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Methamphetamine (Meth) use is known to induce complex neuroinflammatory responses, particularly involving astrocytes and microglia. Building upon our previous research, which demonstrated that Meth stimulates astrocytes to release tumor necrosis factor (TNF) and glutamate, leading to microglial activation, this study investigates the role of the anti-inflammatory cytokine interleukin-10 (IL-10) in this process. Our findings reveal that the presence of recombinant IL-10 (rIL-10) counteracts Meth-induced excessive glutamate release in astrocyte cultures, which significantly reduces microglial activation.

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The influence of gut microbiota in the onset and development of several metabolic diseases has gained attention over the last few years. Diet plays an essential role in gut microbiota modulation. Western diet (WD), characterized by high-sugar and high-fat consumption, alters gut microbiome composition, diversity index, microbial relative levels, and functional pathways.

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Mushroom polysaccharides are recognized as "biological response modifiers". Besides several bioactivities, a growing interest in their prebiotic potential has been raised due to the gut microbiota modulation potential. This review comprehensively summarizes mushroom polysaccharides' biological properties, structure-function relationship, and underlying mechanisms.

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Microglia dynamically reorganize their cytoskeleton to perform essential functions such as phagocytosis of toxic protein aggregates, surveillance of the brain parenchyma, and regulation of synaptic plasticity during neuronal activity bursts. Recent studies have shed light on the critical role of the microtubule cytoskeleton in microglial reactivity and function, revealing key regulators like cyclin-dependent kinase 1 and centrosomal nucleation in the remodeling of microtubules in activated microglia. Concurrently, the role of the actin cytoskeleton is also pivotal, particularly in the context of small GTPases like RhoA, Rac1, and Cdc42 and actin-binding molecules such as profilin-1 and cofilin.

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Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease, involving the selective degeneration of cortical upper synapses in the primary motor cortex (M1). Excitotoxicity in ALS occurs due to an imbalance between excitation and inhibition, closely linked to the loss/gain of astrocytic function. Using the ALS SOD1 mice, we investigated the astrocytic contribution for the electrophysiological alterations observed in the M1 of SOD1 mice, throughout disease progression.

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Microglia, the largest population of brain immune cells, continuously interact with synapses to maintain brain homeostasis. In this study, we use conditional cell-specific gene targeting in mice with multi-omics approaches and demonstrate that the RhoGTPase Rac1 is an essential requirement for microglia to sense and interpret the brain microenvironment. This is crucial for microglia-synapse crosstalk that drives experience-dependent plasticity, a fundamental brain property impaired in several neuropsychiatric disorders.

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Microglia are the largest myeloid cell population in the brain. During injury, disease, or inflammation, microglia adopt different functional states primarily involved in restoring brain homeostasis. However, sustained or exacerbated microglia inflammatory reactivity can lead to brain damage.

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Myelin improves axonal conduction velocity and is essential for nerve development and regeneration. In peripheral nerves, Schwann cells depend on bidirectional mechanical and biochemical signaling to form the myelin sheath but the mechanism underlying this process is not understood. Rho GTPases are integrators of "outside-in" signaling that link cytoskeletal dynamics with cellular architecture to regulate morphology and adhesion.

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The loss of the myelin sheath insulating axons is the hallmark of demyelinating diseases. These pathologies often lead to irreversible neurological impairment and patient disability. No effective therapies are currently available to promote remyelination.

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Article Synopsis
  • Lycopene, known for its antioxidant and anti-inflammatory properties, was studied in a drug delivery system (nanoLPG) derived from red guava to investigate its effects on human skin cells (HaCaT).
  • NanoLPG showed promising characteristics, with stable physical properties and demonstrated antioxidant capacity, effectively preventing DNA damage.
  • The study found that nanoLPG inhibited key enzymes linked to skin aging and maintained cell viability and morphology, suggesting it could be a beneficial ingredient for skin health products.
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Microglia cells dynamically survey the central nervous system microenvironment and, in response to tissue damage inflicted by radiation therapy, disease or infection, undergo morphological and functional changes that culminate in microglia activation. Cell shape transformation can be assessed descriptively or, alternatively, it can be quantified as a continuous variable for parameters including total cell size as well as protrusion length, ramification and complexity. The purpose of the MorphoMacro method is to quantitatively profile multiple and single microglia cells using the available ImageJ platform.

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Microglia are the most prominent immune resident cell population in the central nervous system (CNS). In the healthy CNS, microglia survey their surrounding microenvironment, through recurrent extension and retraction of filopodia-like membrane protrusions, without evident cell body displacement. Microglia undergo dramatic transcriptomic and shape changes upon brain insults or neurodegenerative disease states and adopt a classical immune effector function (producing an extensive array of inflammatory mediators such as cytokines, chemokines, and reactive oxygen species) to re-establish tissue homeostasis.

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Article Synopsis
  • - The IPP protein complex plays a critical role in the myelination process of oligodendrocytes, facilitating communication between cell receptors and the cytoskeleton through mechanical and biochemical signals.
  • - Conditional gene ablation studies in mice highlight the unique function of the Pinch2 isoform, which prevents excessive myelination and aides in myelin stability, in contrast to the effects of Pinch1.
  • - Pinch2 controls myelin formation by regulating RhoA and Cdc42 activities, indicating its essential role as a molecular hub in the signaling pathways necessary for proper oligodendrocyte development and myelin sheath integrity.
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Cells are continuously exposed to physical forces and the central nervous system (CNS) is no exception. Cells dynamically adapt their behavior and remodel the surrounding environment in response to forces. The importance of mechanotransduction in the CNS is illustrated by exploring its role in CNS pathology development and progression.

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Microglia have been increasingly implicated in neurodegenerative diseases (NDs), and specific disease associated microglia (DAM) profiles have been defined for several of these NDs. Yet, the microglial profile in Machado-Joseph disease (MJD) remains unexplored. Here, we characterized the profile of microglia in the CMVMJD135 mouse model of MJD.

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Article Synopsis
  • Exposure to methamphetamine leads to damage in neuronal terminals, but recent findings highlight the key role of glial cells, particularly microglia and astrocytes, in addiction mechanisms.
  • Research indicates that microglial activation from binge meth exposure is mediated through glutamate release from astrocytes and is dependent on TNF/IPR2-Ca signaling.
  • Neurons, while not activating microglia directly, can play a protective role against Meth-induced microglial activation by enhancing certain pathways (arginase 1 expression and CD200/CD200r), suggesting that neuron-glia interactions can mitigate inflammation.
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In addition to the morphophysiological changes experienced by amphibians during metamorphosis, they must also deal with a different set of environmental constraints when they shift from the water to the land. We found that secretes a single peptide ([M + H]+ = 658.38 Da) at the developmental stage that precedes the onset of terrestrial behaviour.

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c-Src was the first protein kinase to be described as capable of phosphorylating tyrosine residues. Subsequent identification of other tyrosine-phosphorylating protein kinases with a similar structure to c-Src gave rise to the concept of Src family kinases (SFKs). Microglia are the resident innate immune cell population of the CNS.

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Methamphetamine (Meth) is a powerful illicit psychostimulant, widely used for recreational purposes. Besides disrupting the monoaminergic system and promoting oxidative brain damage, Meth also causes neuroinflammation, contributing to synaptic dysfunction and behavioral deficits. Aberrant activation of microglia, the largest myeloid cell population in the brain, is a common feature in neurological disorders triggered by neuroinflammation.

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The ramified morphology of microglia and the dynamics of their membrane protrusions are essential for their functions in central nervous system development, homeostasis, and disease. Although their ability to change and control shape critically depends on the actin and actomyosin cytoskeleton, the underlying regulatory mechanisms remain largely unknown. In this study, we systematically analyzed the actomyosin cytoskeleton and regulators downstream of the small GTPase RhoA in the control of microglia shape and function.

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