Histidine decarboxylase

Abstract

The mammalian histidine decarboxylasecDNA encodes for a protein with a molecularmass of 74 kDa that is converted into a 53-55kDa form during post-translational proteolyticprocessing through the ubiquitin-proteasomesystem. The resulting enzyme, histidine decarboxylase,converts L-histidine to histamine. Inthe brain, histamine is an important neurotransmitterand modulator which has beenimplicated in a wide range of physiologicalfunctions and behaviours, such as immunefunction, gastric acid secretion, nutrition, sleep,anxiety, reward and memory. Furthermore,histamine plays a role in human diseases suchas allergy, cancer, epilepsy and autoimmunedisorders. The first part of this chapter focuseson the histamine synthesizing enzyme histidinedecarboxylase, and summarizes what isknown about its molecular structure and catalyticfunction, its distribution in peripheraland central tissues, its cellular localization, thecell types in which it is expressed, and its genestructure, as well as the regulation of its transcriptionand translation. The second part ofthis chapter reviews the literature on neurophysiologicaland behavioural effects of pharmacologicalhistidine decarboxylase inhibitionin the rat, and histidine decarboxylase geneknockout in the mouse. Finally, evidenceimplicating the brain's histamine system inAlzheimer's disease is discussed.© CAB International 2012.