Pregnane X receptor (PXR) represses osteoblast differentiation through repression of the Hedgehog signaling pathway

Pregnane X Receptor Signaling Pathway and Vitamin K: Molecular Mechanisms and Clinical Relevance in Human Health

This review explores the likely clinical impact of Pregnane X Receptor (PXR) activation by vitamin K on human health. PXR, initially recognized as a master regulator of xenobiotic metabolism in liver, emerges as a key regulator influencing intestinal homeostasis, inflammation, oxidative stress, and autophagy. The activation of PXR by vitamin K highlights its role as a potent endogenous and local agonist with diverse clinical implications. Recent research suggests that the vitamin K-mediated activation of PXR highlights this vitamin's potential in addressing pathophysiological conditions by promoting hepatic detoxification, fortifying gut barrier integrity, and controlling pro-inflammatory and apoptotic pathways. PXR activation by vitamin K provides an intricate association with cancer cell survival, particularly in colorectal and liver cancers, to provide new insights into potential novel therapeutic strategies. Understanding the clinical implications of PXR activation by vitamin K bridges molecular mechanisms with health outcomes, further offering personalized therapeutic approaches for complex diseases.

Environmental endocrine disruptors and pregnane X receptor action: A review

The pregnane X receptor (PXR) is a kind of orphan nuclear receptor activated by a series of ligands. Environmental endocrine disruptors (EEDs) are a wide class of molecules present in the environment that are suspected to have adverse effects on the endocrine system by interfering with the synthesis, transport, degradation, or action of endogenous hormones. Since EEDs may modulate human/rodent PXR, this review aims to summarize EEDs as PXR modulators, including agonists and antagonists. The modular structure of PXR is also described, interestingly, the pharmacology of PXR have been confirmed to vary among different species. Furthermore, PXR play a key role in the regulation of endocrine function. Endocrine disruption of EEDs via PXR and its related pathways are systematically summarized. In brief, this review may provide a way to understand the roles of EEDs in interaction with the nuclear receptors (such as PXR) and the related pathways.

Kruppel-like Factors in Skeletal Physiology and Pathologies

Kruppel-like factors (KLFs) belong to a large group of zinc finger-containing transcription factors with amino acid sequences resembling the Drosophila gap gene Krüppel. Since the first report of molecular cloning of the KLF family gene, the number of KLFs has increased rapidly. Currently, 17 murine and human KLFs are known to play crucial roles in the regulation of transcription, cell proliferation, cellular differentiation, stem cell maintenance, and tissue and organ pathogenesis. Recent evidence has shown that many KLF family molecules affect skeletal cells and regulate their differentiation and function. This review summarizes the current understanding of the unique roles of each KLF in skeletal cells during normal development and skeletal pathologies.

The role of pregnane X receptor (PXR) in substance metabolism

As a member of the nuclear receptor (NR) superfamily, pregnane X receptor (PXR; NR1I2) is a ligand-activated transcription factor that plays a crucial role in the metabolism of xenobiotics and endobiotics in mammals. The tissue distribution of PXR is parallel to its function with high expression in the liver and small intestine and moderate expression in the kidney, stomach, skin, and blood-brain barrier, which are organs and tissues in frequent contact with xenobiotics. PXR was first recognized as an exogenous substance receptor regulating metabolizing enzymes and transporters and functioning in detoxification and drug metabolism in the liver. However, further research revealed that PXR acts as an equally important endogenous substance receptor in the metabolism and homeostasis of endogenous substances. In this review, we summarized the functions of PXR in metabolism of different substances such as glucose, lipid, bile acid, vitamin, minerals, and endocrines, and also included insights of the application of PXR ligands (drugs) in specific diseases.