ABC transporters expression

ABC Transporters. Figure 2 ABC-transporter expression in hepatocytes and enterocytes (modified according to www.iwaki-kk.co.jp/bio/specialedition/se02.htm). 

Wagner M, Fickert P, Zollner G, Fuchsbichler A, Silbert D, Tsybrovskyy O, Zatloukal K, Guo GL, Schuetz JD, Gonzalez FJ, Marschall HU, Denk H, Trauner M. Role of farnesoid X receptor in determining hepatic ABC transporter expression and liver injury in bile duct-ligated mice. Gastroenterology 2003 125 825-838. 

Mutch, D.M., Anderle, P., Fiaux, M., Mansourian, R., Vidal, K., Wahli, W., Williamson, G., and Roberts, M.A. (2004) Regional variations in ABC transporter expression along the mouse intestinal tract. Physiolo ccd Genomics, 17 (1), 11-20. 

The blood-brain barrier (BBB) forms a physiological barrier between the central nervous system and the blood circulation. It consists of glial cells and a special species of endothelial cells, which form tight junctions between each other thereby inhibiting paracellular transport. In addition, the endothelial cells of the BBB express a variety of ABC-transporters to protect the brain tissue against toxic metabolites and xenobiotics. The BBB is permeable to water, glucose, sodium chloride and non-ionised lipid-soluble molecules but large molecules such as peptides as well as many polar substances do not readily permeate the battier. 

The multidrug resistance (MDR) phenomenon has first been described in cancer cells which were resistant against several structurally unrelated anticancer dtugs. Mechanistically a high expression of different ABC-transporters (P-gp, MRP) has been identified as the underlying factor. 

In addition to the described lipid pathways mainly operative in macrophages, two further ABC-transporteis, ABCG5 and ABCG8 have been implicated in the efflux of dietary sterols from intestinal cells back into the gut lumen and from liver to the bile duct (Fig 1). Both ABC-transporters form a functional heterodimer with highest expression levels in liver and intestine and are regulated... 

Schmitz G, Langmann T (2003) Function, expression and regulation of human ABC-transporters. In Dutta-Roy, Asim/Spener, Friedrich (eds) Proteins and their fatty acids in health and disease, 1st edn. Wiley-VCH, Weinheim... 

Mahd, B., Masclaux, C., Rauscher, L., Enard, C., and Expert, D. 1995. Differential expression of two siderophore-dependent-iron acquisition pathways in Erwinia cf santhemi 3937 characterization of a novel ferrisiderophore permease of the ABC transporter family. Mol. Microbiol. 18 33-43... 

Fig. 11.4. H uman duodenal expression variability of phosphate and ABC transporters (unpublished data). Shaded box indicates 25-75% of expression range, the line within the box marks the median, and error bars indicate 10-90% of expression range. SLC17A4, sodium phosphate cotransporter SLC25A3,...

Katiyar, S. K., Edlind, T. D., Identification and expression of multidrug resistance-related ABC transporter genes in Candida krusei, Med. Mycol. 2001, 39, 109-116. 

Becker U, Ehrhardt C, Daum N, Baldes C, Schaefer UF, Ruprecht KW, Kim KJ, Lehr CM. Expression of ABC-transporters in human corneal tissue and the transformed cell line HCE-T. J Ocul Pharmacol Ther 23(2) 172-181 (2007). 

---