Retinoic acids

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The retinoic acid ( synonym : vitamin A acids ) are a group of substances consisting of isoprenoid carboxylic acids exist. They form a subgroup of the retinoids and are therefore terpenoids .

presentation

Retinoic acids result from the oxidation of retinal and are therefore oxidation products of retinol :

Vitamin A synthesis

All- trans -retinic acid and 13- cis -retinic acid are formed in the vitamin A metabolism in small amounts .

biochemistry

In addition to the long-known effect of (11-cis-) retinal on the visual process, the influence on gene expression has only been examined in more detail in the last two decades. The active compound here is a retinoic acid, for which the cell has receptors . Retinoic acids exert an influence on growth and cell differentiation - mechanisms that play an important role in embryogenesis and tumor development. Therefore retinoic acids are in conditions such as acne , psoriasis locally therapeutically or tumors used as drugs. They have a strong teratogenic effect in systemic therapy . Retinoic acids bind to the Retinoic Acid Orphan Receptor , with effects on metabolism , the immune system , embryonic development , angiogenesis and the circadian rhythm . Retinoic acids activate regulatory T cells . There is also a non-canonical role for the retinoic acid receptor subtype RARα at neuronal synapses. In the synapse , (RARα) promotes local translation of AMPA receptors in response to persistent low neuronal activity. Increasing the AMPA receptors in this way strengthens the synapses in the form of homeostatic synaptic neuronal plasticity (HSP). HSP shifts total synaptic strengths across the neuron while maintaining relative synaptic weights. HSP is bidirectional; the synapse may "enlarge" in response to decreased neural activity or "decrease" in response to increased neural activity. It is assumed that HSP plays an important role in keeping synaptic activity in the physiological range and in preventing information loss through a "maxed-out" signal. The mechanistic basis of HSP is poorly understood, especially when it comes to synaptic downscaling.

Web links

Individual evidence

  1. ↑ S. Shimozono, T. Iimura et al. a .: Visualization of an endogenous retinoic acid gradient across embryonic development. In: Nature. Volume 496, number 7445, April 2013, pp. 363-366, doi : 10.1038 / nature12037 . PMID 23563268 .
  2. ↑ KomNet NRW: Evaluation of tretinoin as a medicinal and hazardous substance
  3. ↑ HS Ranhotra: The interplay between retinoic acid receptor-related orphan receptors and human diseases. In: J Recept Signal Transduct Res. (2012), Vol. 32, No. 4, pp. 181-189. doi : 10.3109 / 10799893.2012.692120 . PMID 22686165 .
  4. ^ AC Ross: Vitamin A and retinoic acid in T cell-related immunity. In: Am J Clin Nutr. (2012), Vol. 96, No. 5, pp. 1166S-1172S. doi : 10.3945 / ajcn.112.034637 . PMID 23053562 ; PMC 3471201 (free full text).
  5. ↑ Brandon J. Walters and Sheena A. Josselyn: Retinoic acid receptor plays both sides of homeostatic plasticity. In: Proceedings of the National Academy of Sciences. 2019, doi : 10.1073 / pnas.1902400116 .