Notch signaling in thyrocytes is essential for adult thyroid function and mammalian homeostasis

Phthalates and Non-Phthalate Plasticizers and Thyroid Dysfunction: Current Evidence and Novel Strategies to Reduce Their Spread in Food Industry and Environment

Thyroid hormones (THs) play a crucial role in various biological functions, including metabolism, cell growth, and nervous system development, and any alteration involving the structure of the thyroid gland and TH secretion may result in thyroid disease. Growing evidence suggests that phthalate plasticizers, which are commonly used in a wide range of products (e.g., food packaging materials, children's toys, cosmetics, medical devices), can impact thyroid function, primarily affecting serum levels of THs and TH-related gene expression. Like phthalate compounds, recently introduced alternative plasticizers can leach from their source material into the environment, particularly into foods, although so far only a very limited number of studies have investigated their thyroid toxicity. This review aimed at summarizing the current knowledge on the role of phthalate and non-phthalate plasticizers in thyroid dysfunction and disease, describing the major biological mechanisms underlying this relationship. We will also focus on the food industry as one of the main players for the massive spread of such compounds in the human body, in turn conveyed by edible compounds. Given the increasing worldwide use of plasticizers and the essential role of THs in humans, novel strategies should be envisaged to reduce this burden on the thyroid and, in general, on human health.

The Jag2/Notch1 signaling axis promotes sebaceous gland differentiation and controls progenitor proliferation

The sebaceous gland (SG) is a vital appendage of the epidermis, and its normal homeostasis and function is crucial for effective maintenance of the skin barrier. Notch signaling is a well-known regulator of epidermal differentiation, and has also been shown to be involved in postnatal maintenance of SGs. However, the precise role of Notch signaling in regulating SG differentiation in the adult homeostatic skin remains unclear. While there is evidence to suggest that Notch1 is the primary Notch receptor involved in regulating the differentiation process, the ligand remains unknown. Using monoclonal therapeutic antibodies designed to specifically inhibit of each of the Notch ligands or receptors, we have identified the Jag2/Notch1 signaling axis as the primary regulator of sebocyte differentiation in mouse homeostatic skin. Mature sebocytes are lost upon specific inhibition of the Jag2 ligand or Notch1 receptor, resulting in the accumulation of proliferative stem/progenitor cells in the SG. Strikingly, this phenotype is reversible, as these stem/progenitor cells re-enter differentiation when the inhibition of Notch activity is lifted. Thus, Notch activity promotes correct sebocyte differentiation, and is required to restrict progenitor proliferation.