retinoid metabolic process

Definition

Target type: biologicalprocess

The chemical reactions and pathways involving retinoids, any member of a class of isoprenoids that contain or are derived from four prenyl groups linked head-to-tail. Retinoids include retinol and retinal and structurally similar natural derivatives or synthetic compounds, but need not have vitamin A activity. [ISBN:0198506732]

Retinoid metabolic process is a complex and essential biological process that involves the conversion of vitamin A and its derivatives, collectively known as retinoids, into various active forms that are critical for numerous physiological functions. The process begins with the absorption of dietary vitamin A (retinol) in the small intestine, where it is incorporated into chylomicrons and transported to the liver. In the liver, retinol is esterified to retinyl esters, which are stored in hepatic stellate cells. When needed, retinyl esters are hydrolyzed back to retinol and released into the bloodstream bound to retinol-binding protein (RBP). This complex is then transported to various target tissues, where it can be taken up by cells via specific receptors. Once inside the cell, retinol can undergo a series of enzymatic reactions to generate different retinoid forms, including retinaldehyde and retinoic acid. Retinaldehyde is a key intermediate in the visual cycle, where it is involved in the conversion of light into a nerve impulse. Retinoic acid is a potent hormone that plays critical roles in cell growth, differentiation, and development. It is also involved in regulating gene expression by binding to nuclear receptors, retinoic acid receptors (RARs) and retinoid X receptors (RXRs). These receptors act as transcription factors, modulating the expression of target genes involved in various biological processes. The enzymes involved in retinoid metabolism include retinol dehydrogenases, retinaldehyde reductases, and cytochrome P450 enzymes. These enzymes exhibit tissue-specific expression, contributing to the diverse roles of retinoids in different organs. Disruptions in retinoid metabolism can lead to various disorders, including night blindness, xerophthalmia, and developmental defects. In addition, retinoid metabolism is also implicated in cancer development, as retinoids can act as both tumor suppressors and promoters depending on the context. Overall, retinoid metabolic process is a highly regulated and vital pathway that ensures adequate levels of active retinoids for maintaining normal physiological function. This intricate process involves the conversion of retinol into various bioactive forms, their transport to target tissues, and their subsequent action in regulating gene expression and influencing various biological processes.'
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Proteins (20)

Compounds (172)