Browsing by Author "Marques, Rita"
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- The nuclear levels of thioredoxin reductase 1, gamma-H2AX, and yap are modulated by primary cilia in response to high glucose levelsPublication . Marques, Rita; Paiva, Mariana; Ginete, Catarina; Nolasco, Sofia; Marinho, Susana H.; Veiga, Luisa; Brito, Miguel; Soares, Helena; Carmona, BrunoDiabetes is a condition characterized by impaired regulation of blood glucose levels, leading to various complications such as hypertension, cardiovascular disease, and retinopathy. Diabetic retinopathy (DR), caused by a disrupted retinal blood barrier, is associated with oxidative stress resulting from dysregulated glucose levels in the retina. The primary cilium, an organelle involved in energy balance and glucose homeostasis, has been implicated in the development of various diseases known as ciliopathies, which include overlapping phenotypes such as obesity, diabetes, and retinopathy. This study aims to investigate the impact of high glucose levels on primary cilia assembly in retinal pigment epithelium (RPE-1) cell cultures and explore the role of cilia in the cellular response to high glucose levels. RPE-1 cells were grown in media supplemented with different glucose concentrations (5 mM, 25 mM, and 5 mM glucose + 20 mM mannitol), and cilia assembly was induced before or after glucose supplementation. The results revealed that glucose supplementation did not affect the number of ciliated cells, but cells supplemented with 25 mM glucose exhibited shorter cilia. To understand the role of cilia in response to high glucose levels, the nuclear levels of thioredoxin reductase 1 (TRXR1), a key enzyme involved in combating oxidative stress triggered by hyperglycemia, were evaluated. Additionally, γH2AX, a marker of DNA breaks and cellular senescence, and YAP, a Hippo pathway effector, were examined. It was observed that glucose supplementation, particularly at high levels (25 mM), influenced the nuclear levels of TRXR1, γH2AX, and YAP. Notably, the presence of cilia modulated the cellular response to high glucose levels, modulating the levels of these proteins. These preliminary findings indicate that primary cilia significantly influence the cellular response to high glucose concentrations, which are known to induce oxidative stress and potentially contribute to the development of DR.
- Tubulin acetylation and the cellular mechanosensing and stress responsePublication . Carmona, Bruno; Delgado, Inês L. S.; Nolasco, Sofia; Marques, Rita; Gonçalves, João; Soares, Helena; Halasa, M.; Wawruszak, A.Microtubule (MT) acetylation has emerged as a critical regulator of cellular stress responses, integrating mechanical and oxidative stimuli to support cellular adaptability and survival. This post-translational modification (PTM) enhances MT flexibility and resilience, enabling cells to withstand mechanical challenges such as changes in extracellular matrix stiffness and applied forces. Through its impact on MT physical properties, acetylation minimizes cytoskeletal breakage, reducing the need for constant remodeling and supporting cellular integrity under mechanical stress. Furthermore, tubulin acetylation regulates intracellular trafficking by modulating interactions with molecular motors, allowing for efficient cargo transport and precise spatial organization without disrupting the MT network. In the context of oxidative stress, tubulin acetylation responds to redox imbalances by stabilizing MTs and influencing cellular pathways that regulate reactive oxygen species (ROS). This modification is linked to enhanced antioxidant responses, autophagy regulation, and mitochondrial dynamics, highlighting its role in maintaining cellular homeostasis under oxidative conditions. The dual function of tubulin acetylation, responding to and integrating signals from mechanical and oxidative stress, acts as a bridging mechanism between physical and chemical signaling pathways. Consequently, it has the potential to be a therapeutic target in diseases characterized by dysregulated stress responses, including neurodegenerative disorders, cancer, and cardiovascular conditions. Despite significant progress having been made, unanswered questions persist, particularly regarding the molecular mechanisms by which acetylated MTs encode spatial and functional information and their interplay with other tubulin PTMs.
- Tubulin acetylation: a critical regulator of microtubule functionPublication . Delgado, Inês L.; Carmona, Bruno; Nolasco, Sofia; Marques, Rita; Gonçalves, João; Soares, Helena; Halasa, M.; Wawruszak, A.The cytoskeleton is conserved throughout the eukaryotic lineage and consists of a complex dynamic network mainly composed of three distinct polymers: microtubules (MTs), actin filaments, and intermediate filaments. MTs are polymers of α/β-tubulin heterodimers, playing a myriad of distinct cellular functions, and are the main components of complex structures like the mitotic spindle, cilia, and centrioles. Post-translational modifications (PTMs) regulate the function and increase the complexity of the α/β-tubulin heterodimer pools. One of the PTMs that has been extensively studied is the acetylation of lysine 40 (K40) on α-tubulin, which specifically occurs inside the MT lumen. Acetylation plays a crucial role in controlling the stability and function of MTs in response to signals from within and outside the cell. It impacts the cytoplasm's 3D arrangement and important cellular activities like intracellular transport, cell division, polarity, and migration. Recent research has also emphasized the significance of this PTM in regulating the mechanical properties of MTs and cellular sensing. The levels and activity of MT acetyltransferases and deacetylases are tightly regulated through various transcriptional, post-transcriptional, and post-translational mechanisms, including miRNAs, phosphorylation, protein-protein interactions, and regulated localization between the nucleus and cytoplasm. These regulatory processes involve components of diverse signaling pathways, and their deregulation has been implicated in numerous diseases, including neurological disorders, cancer, and cardiac conditions.