Search

To identify novel genes associated with intellectual disability (ID) in four unrelated families.

ATP6V1B2encodes a subunit of the lysosomal transmembrane proton pump necessary for adequate functioning of several acid hydrolases. De novomonoallelic variants of this gene have been associated with two distinct phenotypes: Zimmermann‐Laband syndrome 2 (ZLS2), an intellectual deficiency/multiple malformation syndrome, and dominant deafness onychodystrophy (DDOD), a multiple malformation syndrome without cognitive involvement. Epilepsy is not observed in DDOD, is variably present in ZLS2, but is a common feature in Zimmermann‐Laband syndrome 1 (ZLS1) (caused by monoallelic pathogenic variants in KCNH1) and Zimmermann‐Laband syndrome‐like (ZLSL) (associated with KCNK4variants). Herein, we report a case of an infant with severe epileptic encephalopathy with microcephaly and profound developmental delay, associated with a novel de novoloss‐of‐function variant in ATP6V1B2, diagnosed by whole‐exome sequencing. This finding expands the spectrum of ATP6V1B2‐associated disorders and adds ATP6V1B2as a new member for the growing list of early‐onset epileptic encephalopathy genes. [Published with video sequence].

This study aims to comprehensively delineate the phenotypic spectrum of ACTL6B-related disorders, previously associated with both autosomal recessive and autosomal dominant neurodevelopmental disorders. Molecularly, the role of the nucleolar protein ACTL6B in contributing to the disease has remained unclear.

Maleimides consist of an important class of compounds easily synthesized with multiple functional group modification that provides expressive pharmacological properties including, antitumoral activity, mediated mainly by oxidative stress. For this reason, the present study was designed to evaluate the cytotoxicity and the role of reactive oxygen species (ROS) in maleimide-induced cell death. Cell viability assays were performed to determine the cell death type in leukemia cell line induced by the compounds. The oxidative stress in maleimidetreated cells was characterized by antioxidant enzymes activities, intracellular ROS generation, and lipid peroxidation. In addition, we evaluated mitochondrial membrane potential and ATP level. Maleimide derivatives exhibited cytotoxic effects in leukemia cells with significantly increased ROS generation. However, cell viability was partly restored by catalase-treated cells. Caspases activities and caspase-independent key genes related to apoptosis were not altered by maleimides, suggesting necrosis as the main cell death process. Maleimide-induced necrosis was associated with oxidative stress, as an imbalance between ROS levels and glutathione reductase (GR) activity. This damage was also demonstrated by loss of mitochondrial membrane potential (MMP) and ATP depletion in cells treated with maleimide derivatives. These findings strongly confirmed that maleimide derivatives promoted cell death in leukemia cells triggered by oxidative stress, indicating that these compounds might be promising antitumor agents or lead molecules.

Melanoma is a very aggressive type of skin cancer. Mutation in BRAF and NRAS are often found in patients with this disease. Therefore, in recent years the search for new molecules that inhibit these proteins has been intensified. After many years with no new treatments for melanoma, the U.S. Food and Drug Administration (FDA) recently approved vemurafenib. However, many patients have already acquired resistance and have experienced severe side effects. Therefore, this work aims to evaluate a new set of compounds including allylic isothiouronium salts (1, 2 and 3), N-phenyl-substituted analog (4) and isothiosemicarbazide salts (5 and 6) for their potential antimelanoma activity. To this end, viability assay, cell cycle analysis, expression of NRAS and BRAF, as well as migration and invasion assay were performed with different melanoma cell lines. Isothiouronium salts 1-3 presented CC50 (concentration required to reduce the cell number by 50%) in a range of 7-28 μM. Furthermore, salt 1 significantly decreased the expression of NRAS. However, cells incubated with these salts did not disturb the cell cycle phases; instead, an increase in the number of apoptotic cells was observed. Regarding potential antiinvasion effects, both 1 and 2 prevented cell migration as well as cell invasion. Finally, when salts 1 and 2 were associated with vemurafenib, a marked decrease in cell viability was observed when compared to the compounds incubated alone. Briefly, the salts exhibited interesting results, especially 1, which decreased the expression of NRAS, increased apoptotic cells and, when combined with vemurafenib, resulted in a synergistic effect. Therefore, we intend to test compound 1 in pre-clinical studies.

The Melanocortin-4 Receptor (MC4R) plays a pivotal role in energy homeostasis. We used human MC4Rmutations associated with an increased or decreased risk of obesity to dissect mechanisms that regulate MC4R function. Most obesity-associated mutations impair trafficking to the plasma membrane (PM), whereas obesity-protecting mutations either accelerate recycling to the PM or decrease internalization, resulting in enhanced signaling. MC4R mutations that do not affect canonical Gαsprotein-mediated signaling, previously considered to be non-pathogenic, nonetheless disrupt agonist-induced internalization, β-arrestin recruitment, and/or coupling to Gαs, establishing their causal role in severe obesity. Structural mapping reveals ligand-accessible sites by which MC4R couples to effectors and residues involved in the homodimerization of MC4R, which is disrupted by multiple obesity-associated mutations. Human genetic studies reveal that endocytosis, intracellular trafficking, and homodimerization regulate MC4R function to a level that is physiologically relevant, supporting the development of chaperones, agonists, and allosteric modulators of MC4R for weight loss therapy.