High-Throughput Microscopy Analysis of Mitochondrial Membrane Potential in 2D and 3D Models.

Recent proteomic, metabolomic, and transcriptomic studies have highlighted a connection between changes in mitochondria physiology and cellular pathophysiological mechanisms. Secondary assays to assess the function of these organelles appear fundamental to validate these -omics findings. Although mitochondrial membrane potential is widely recognized as an indicator of mitochondrial activity, high-content imaging-based approaches coupled to multiparametric to measure it have not been established yet.

Overexpression of , a Gene on Human Chromosome , Alters Cell Redox and Mitochondrial Function in Enamel Cells.

The regulator of calcineurin (RCAN1) has been implicated in the pathogenesis of Down syndrome (DS). Individuals with DS show dental abnormalities for unknown reasons, and RCAN1 levels have been found to be elevated in several tissues of DS patients. A previous microarray analysis comparing cells of the two main formative stages of dental enamel, secretory and maturation, showed a significant increase in RCAN1 expression in the latter.

Mitochondria modulate ameloblast Ca signaling.

The role of mitochondria in enamel, the most mineralized tissue in the body, is poorly defined. Enamel is formed by ameloblast cells in two main sequential stages known as secretory and maturation. Defining the physiological features of each stage is essential to understand mineralization.

Calcium Transport in Specialized Dental Epithelia and Its Modulation by Fluoride.

Most cells use calcium (Ca) as a second messenger to convey signals that affect a multitude of biological processes. The ability of Ca to bind to proteins to alter their charge and conformation is essential to achieve its signaling role. Cytosolic Ca (Ca) concentration is maintained low at ~100 nM so that the impact of elevations in Ca is readily sensed and transduced by cells.

Mitochondrial Function in Enamel Development.

Enamel is the most calcified tissue in vertebrates. Enamel formation and mineralization is a two-step process that is mediated by ameloblast cells during their secretory and maturation stages. In these two stages, ameloblasts are characterized by different morphology and function, which is fundamental for proper mineral growth in the extracellular space.

TRPM7 activation potentiates SOCE in enamel cells but requires ORAI.

Calcium (Ca) release-activated Ca (CRAC) channels mediated by STIM1/2 and ORAI (ORAI1-3) proteins form the dominant store-operated Ca entry (SOCE) pathway in a wide variety of cells. Among these, the enamel-forming cells known as ameloblasts rely on CRAC channel function to enable Ca influx, which is important for enamel mineralization. This key role of the CRAC channel is supported by human mutations and animal models lacking STIM1 and ORAI1, which results in enamel defects and hypomineralization.

Fluoride exposure alters Ca signaling and mitochondrial function in enamel cells.

Fluoride ions are highly reactive, and their incorporation in forming dental enamel at low concentrations promotes mineralization. In contrast, excessive fluoride intake causes dental fluorosis, visually recognizable enamel defects that can increase the risk of caries. To investigate the molecular bases of dental fluorosis, we analyzed the effects of fluoride exposure in enamel cells to assess its impact on Ca signaling.

Differential regulation of Ca influx by ORAI channels mediates enamel mineralization.

Store-operated Ca entry (SOCE) channels are highly selective Ca channels activated by the endoplasmic reticulum (ER) sensors STIM1 and STIM2. Their direct interaction with the pore-forming plasma membrane ORAI proteins (ORAI1, ORAI2, and ORAI3) leads to sustained Ca fluxes that are critical for many cellular functions. Mutations in the human gene result in immunodeficiency, anhidrotic ectodermal dysplasia, and enamel defects.

Monoamine oxidase-dependent histamine catabolism accounts for post-ischemic cardiac redox imbalance and injury.

Monoamine oxidase (MAO), a mitochondrial enzyme that oxidizes biogenic amines generating hydrogen peroxide, is a major source of oxidative stress in cardiac injury. However, the molecular mechanisms underlying its overactivation in pathological conditions are still poorly characterized. Here, we investigated whether the enhanced MAO-dependent hydrogen peroxide production can be due to increased substrate availability using a metabolomic profiling method.

Protein Localization at Mitochondria-ER Contact Sites in Basal and Stress Conditions.

Mitochondria-endoplasmic reticulum (ER) contacts (MERCs) are sites at which the outer mitochondria membrane and the Endoplasmic Reticulum surface run in parallel at a constant distance. The juxtaposition between these organelles determines several intracellular processes such as to name a few, Ca and lipid homeostasis or autophagy. These specific tasks can be exploited thanks to the enrichment (or re-localization) of dedicated proteins at these interfaces.

Calcium Handling by Endoplasmic Reticulum and Mitochondria in a Cell Model of Huntington's Disease.

Huntington disease (HD) is caused by the CAG (Q) expansion in exon 1 of the IT15 gene encoding a polyglutamine (poly-Q) stretch of the Huntingtin protein (Htt). In the wild type protein, the repeats specify a stretch of up 34 Q in the N-terminal portion of Htt. In the pathological protein (mHtt) the poly-Q tract is longer.