User:Akash Bhadra/Structural Analysis and Development of Notum Fragment Screening Hits
Introduction
Wnt signalling is implicated in processes involved in animal embryonic development, adult tissue homeostasis, and regeneration. [1] As the enzyme Notum can render Wnt inactive, it is a biologically and medically important target. In Structural Analysis and Development of Notum Fragment Screening Hits[2], the authors aim to discover small-molecule inhibitors of Notum, which suppresses Wnt signaling by removing a lipid modification from Wnt proteins. ContentsBiological role of the Wnt pathwaySignalling proteins are used by cells during development and adult homeostasis to facilitate communication and coordinate their activities. Wnt is a family of such signalling pathways, which are important as they represent links between normal development and tumorigenesis, and Wn proteins control a wide range of physiological functions, such as vertebrate axis specification, stem cell maintenance, and synaptogenesis. [3] Wnt ligands bind Frizzled receptors and co-receptors (such as LRP5/6) to stabilize β-catenin and direct context-dependent transcriptional programs that control proliferation, differentiation and morphogenesis. [4] Problems in Wnt signalling are associated with various diseases, including cancer, vascular disease, Alzheimer’s disease, and developmental defects. Notum significance in Wnt signallingNotum is a negative regulator in both development and adult tissues. Notum is a secreted carboxylesterase that plays a key extracellular role in shaping Wnt signaling domains. It specifically removes the O-linked palmitoleate from Wnt ligands, a lipid modification required for receptor engagement. By deacylating Wnt proteins, Notum suppresses their signaling capacity, thereby modulating morphogen gradients and restraining Wnt-dependent proliferation. This enzymatic activity was structurally established in work showing how Notum accommodates the Wnt lipid within its catalytic pocket and catalyzes its hydrolysis. RelevanceStructural highlights
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