Unfolded Protein Response Signaling in Liver Disorders: A 2023 Updated Review

• Published in: International journal of molecular sciences Vol. 24; no. 18; p. 14066
• Main Authors: Shreya, Smriti, Grosset, Christophe F., Jain, Buddhi Prakash
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 14.09.2023; MDPI
• Subjects: Alzheimer's disease; B cells; Biochemistry, Molecular Biology; Biosensors; Carbohydrates; Cellular Biology; Chemical bonds; Development and progression; Endoplasmic reticulum; Enzymes; Fatty liver; Genes; Genetic transcription; Health aspects; Hepatitis; Homeostasis; Inositol; Kinases; Life Sciences; Liver; Liver cancer; Localization; Medical research; Medicine, Experimental; Membrane proteins; Metabolism; Molecular biology; Neurophysiology; Phosphorylation; Physiological aspects; Polypeptides; Protein biosynthesis; Protein folding; Protein kinases; Review; Ribonucleic acid; RNA; Sensors; Transcription factors; Virus diseases; Well being; unfolded protein response; non-alcoholic fatty liver disease; liver disorders; endoplasmic reticulum; hepatocellular carcinoma
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms241814066

Endoplasmic reticulum (ER) is the site for synthesis and folding of secreted and transmembrane proteins. Disturbance in the functioning of ER leads to the accumulation of unfolded and misfolded proteins, which finally activate the unfolded protein response (UPR) signaling. The three branches of UPR—IRE1 (Inositol requiring enzyme 1), PERK (Protein kinase RNA-activated (PKR)-like ER kinase), and ATF6 (Activating transcription factor 6)—modulate the gene expression pattern through increased expression of chaperones and restore ER homeostasis by enhancing ER protein folding capacity. The liver is a central organ which performs a variety of functions which help in maintaining the overall well-being of our body. The liver plays many roles in cellular physiology, blood homeostasis, and detoxification, and is the main site at which protein synthesis occurs. Disturbance in ER homeostasis is triggered by calcium level imbalance, change in redox status, viral infection, and so on. ER dysfunction and subsequent UPR signaling participate in various hepatic disorders like metabolic (dysfunction) associated fatty liver disease, liver cancer, viral hepatitis, and cholestasis. The exact role of ER stress and UPR signaling in various liver diseases is not fully understood and needs further investigation. Targeting UPR signaling with drugs is the subject of intensive research for therapeutic use in liver diseases. The present review summarizes the role of UPR signaling in liver disorders and describes why UPR regulators are promising therapeutic targets.