Subcellular dynamics of estrogen-related receptors involved in transrepression through interactions with scaffold attachment factor B1

FoxP2 protein decreases at a specific region in the chick midbrain after hatching

Forkhead-box subclass P member 2 (FOXP2/FoxP2) protein, a transcription factor, regulates the development of certain brain functions, including human speech and animal vocalization. Although rapid progress has been made in demonstrating a relationship between FoxP2 expression in the brain and vocalization of the zebra finch, a typical vocal learner, the relationship in avian vocal non-learners, including chickens remains elusive. Because the midbrain plays a key role in innate vocalization development, we analyzed the FoxP2 protein in the midbrain of chicks, which do not cheep before hatching but cheep and call after hatching. Western blot analyses showed a significant reduction in FoxP2 protein in the chick midbrain after hatching compared with the findings before hatching. Quantitative immunohistochemistry revealed that FoxP2-immunoreactive (ir) cells significantly decreased at the stratum gris fibrosum (SGFS) of the optic tectum in the chick midbrain after hatching compared with the findings before hatching. These findings support the notion that FoxP2-ir cell numbers decrease at a specific region in the midbrain after hatching may be involved in innate vocalization of avian vocal non-learners.

Tox21-Based Comparative Analyses for the Identification of Potential Toxic Effects of Environmental Pollutants

Chemical pollution has become a prominent environmental problem. In recent years, quantitative high-throughput screening (qHTS) assays have been developed for the fast assessment of chemicals' toxic effects. Toxicology in the 21st Century (Tox21) is a well-known and continuously developing qHTS project. Recent reports utilizing Tox21 data have mainly focused on setting up mathematical models for in vivo toxicity predictions, with less attention to intuitive qHTS data visualization. In this study, we attempted to reveal and summarize the toxic effects of environmental pollutants by analyzing and visualizing Tox21 qHTS data. Via PubMed text mining, toxicity/structure clustering, and manual classification, we detected a total of 158 chemicals of environmental concern (COECs) from the Tox21 library that we classified into 13 COEC groups based on structure and activity similarities. By visualizing these COEC groups' bioactivities, we demonstrated that COECs frequently displayed androgen and progesterone antagonistic effects, xenobiotic receptor agonistic roles, and mitochondrial toxicity. We also revealed many other potential targets of the 13 COEC groups, which were not well illustrated yet, and that current Tox21 assays may not correctly classify known teratogens. In conclusion, we provide a feasible method to intuitively understand qHTS data.

Molecular dynamics of estrogen-related receptors and their regulatory proteins: roles in transcriptional control for endocrine and metabolic signaling

Estrogen-related receptor (ERR) is a member of the nuclear receptor (NR) superfamily and has three subtypes α, β, and γ. Despite their strong homology with estrogen receptor (ER) α, ERRs cannot accommodate endogenous hormones. However, they are able to regulate gene expression without ligand binding. ERRα and ERRγ orchestrate the expression of genes involved in bioenergetic pathways, while ERRβ controls placental development and stem cell maintenance. Evidence from recent studies, including clinical research, has also demonstrated close associations of ERRs with the pathophysiology of hormone-related cancers and metabolic disorders including type 2 diabetes mellitus. This review summarizes the basic knowledge and recent advances in ERRs and their associated proteins, focusing on the subcellular dynamics involved in transcriptional regulation. Fluorescent protein labeling enabled monitoring of ERRs in living cells and revealed previously unrecognized characteristics. Using this technique, we demonstrated a role of ERRβ in controlling estrogen signaling by regulating the subnuclear dynamics of ligand-activated ERα. Visualization of ERRs and related proteins and subsequent analyses also revealed a function of ERRγ in promoting liver lactate metabolism in association with LRPGC1, a recently identified lactic acid-responsive protein. These findings suggest that ERRs activate unique transregulation mechanisms in response to extracellular stimuli such as hormones and metabolic signals, implying an adaptive system behind the cellular homeostatic regulation by orphan NRs. Control of subcellular ERR dynamics will contribute toward the development of therapeutic approaches to treat various diseases including hormone-related cancers and metabolic disorders associated with abnormal ERR signaling pathways.