• TRPV Cation Channels/metabolism
• TRPV Cation Channels/antagonists & inhibitors
• Humans
• Calcium/metabolism
• Human Umbilical Vein Endothelial Cells/metabolism
• Endothelial Cells/metabolism
• Endothelial Cells/drug effects
• Nanoparticles/chemistry
• Gold/chemistry
• Gold/pharmacology
• Particle Size
• Metal Nanoparticles/chemistry
• Cells, Cultured

• CP: Immunology
• CP: Metabolism
• T cells
• autoimmune disease
• glucose metabolism
• histone acetylation
• juvenile idiopathic arthritis
• pyruvate dehydrogenase

As the major hub of metabolic activity and an organelle sequestering pro-apoptogenic intermediates, mitochondria lie at the crossroads of cellular decisions of death and survival. Intracellular calcium is a key regulator of these outcomes with rapid, uncontrolled uptake into mitochondria, activating pro-apoptotic cascades that trigger cell death. Here, we show that calcium uptake and mitochondrial metabolism in murine T-regulatory cells (Tregs) is tuned by Notch1 activity. Based on analysis of Tregs and the HEK cell line, we present evidence that modulation of cellular calcium dynamics underpins Notch1 regulation of mitochondrial homeostasis and consequently anti-apoptotic activity. Targeted siRNA-mediated ablations reveal dependency on molecules controlling calcium release from the endoplasmic reticulum (ER) and the chaperone, glucose-regulated protein 75 (Grp75), the associated protein Voltage Dependent Anion Channel (VDAC)1 and the Mitochondrial Calcium Uniporter (MCU), which together facilitate ER calcium transfer and uptake into the mitochondria. Endogenous Notch1 is detected in immune-complexes with Grp75 and VDAC1. Deficits in mitochondrial oxidative and survival in Notch1 deficient Tregs, were corrected by the expression of recombinant Notch1 intracellular domain, and in part by recombinant Grp75. Thus, the modulation of calcium dynamics and consequently mitochondrial metabolism underlies Treg survival in conditions of nutrient stress. This work positions a key role for Notch1 activity in these outcomes.

• Grp75
• NOTCH1
• Tregs
• apoptosis
• calcium
• mammalian cells
• mitochondria
• oxphos

The G-protein–coupled estrogen receptor (GPER) mediates non-genomic action of estrogen. Due to its differential expression in some tumors as compared to the original healthy tissues, the GPER has been proposed as a therapeutic target. Accordingly, the non-steroidal GPER agonist G-1, which has often demonstrated marked cytotoxicity in experimental models, has been suggested as a novel anticancer agent for several sensitive tumors. We recently revealed that cell lines derived from acute T-cell (query) lymphoblastic leukemia (T-ALL) express the GPER. Here, we address the question whether G-1 is cytotoxic to T-ALL. We have shown that G-1 causes an early rise of intracellular Ca²⁺, arrests the cell cycle in G2/M, reduces viability, and provokes apoptosis in T-ALL cell lines. Importantly, G-1 caused destabilization and depolymerization of microtubules. We assume that it is a disturbance of the cytoskeleton that causes G-1 cytotoxic and cytostatic effects in our model. The observed cytotoxic effects, apparently, were not triggered by the interaction of G-1 with the GPER as pre-incubation with the highly selective GPER antagonist G-36 was ineffective in preventing the cytotoxicity of G-1. However, G-36 prevented the intracellular Ca²⁺ rise provoked by G-1. Finally, G-1 showed only a moderate negative effect on the activation of non-leukemic CD4⁺ lymphocytes. We suggest G-1 as a potential antileukemic drug.

• Consejo Nacional de Ciencia y Tecnología

• cancer
• metabolomics
• photodynamic therapy
• rhodium nanoparticles
• transcriptomics

Gamma-aminobutyric acid (GABA) is considered the primary inhibitory neurotransmitter in the human cortex. However, whether GABA regulates melanogenesis has not been comprehensively elucidated. In this study, we reveal that GABA (20 mM) significantly inhibited α-melanocyte-stimulating hormone (α-MSH)-induced extracellular (from 354.9% ± 28.4% to 126.5% ± 16.0%) and intracellular melanin contents (from 236.7% ± 11.1% to 102.7% ± 23.1%) in B16F10 melanoma cells, without inducing cytotoxicity. In addition, α-MSH-induced hyperpigmentation in zebrafish larvae was inhibited from 246.3% ± 5.4% to 116.3% ± 3.1% at 40 mM GABA, displaying no apparent cardiotoxicity. We also clarify that the GABA-mediated antimelanogenic properties were related to the direct inhibition of microphthalmia-associated transcription factor (MITF) and tyrosinase expression by inhibiting cyclic adenosine monophosphate (cAMP) and cAMP response element-binding protein (CREB). Furthermore, under α-MSH stimulation, GABA-related antimelanogenic effects were mediated through the GABA_A and GABA_B receptors, with subsequent inhibition of Ca²⁺ accumulation. In B16F10 melanoma cells and zebrafish larvae, pretreatment with bicuculline, a GABA_A receptor antagonist, and CGP 46381, a GABA_B receptor antagonist, reversed the antimelanogenic effect of GABA following α-MSH treatment by upregulating Ca²⁺ accumulation. In conclusion, our results indicate that GABA inhibits α-MSH-induced melanogenesis. Hence, in addition to the health benefits of GABA in the central nervous system, it could ameliorate hyperpigmentation disorders.

• Ca2+
• GABA
• GABA receptor
• melanogenesis

• calcium cycling
• cardiotoxicity
• cholesterol
• neuronal function
• polycyclic aromatic hydrocarbons
• sensory function

• Animals
• Ecosystem
• Fishes/physiology
• Heart/drug effects
• Nervous System/drug effects
• Oxidative Stress/drug effects
• Petroleum/analysis
• Petroleum/toxicity
• Petroleum Pollution/analysis
• Polycyclic Aromatic Hydrocarbons/analysis
• Polycyclic Aromatic Hydrocarbons/toxicity
• Water Pollutants, Chemical/analysis
• Water Pollutants, Chemical/toxicity