Author: Komada, Masayuki

Source: Current Drug Discovery Technologies, Volume 5, Number 1, March 2008 , pp. 78-84(7)

Publisher: Bentham Science Publishers

Abstract:

Growth factor-activated receptor tyrosine kinases (RTKs) undergo rapid endocytosis and degradation in lysosomes. This process, known as receptor downregulation, is essential to prevent the overgrowth of cells by terminating signal transduction from activated RTKs. Thus, defects in RTK downergulation lead to cell proliferative disorders such as cancer. Upon endocytosis, RTKs are delivered to endosomes, from where they are further transported to lysosomes. Ubiquitin serves as a sorting signal that is tagged on activated RTKs and directs their trafficking from endosomes to lysosomes. On the endosomal membrane, ubiquitinated RTKs are sorted by coordinated actions of the class E vacuolar protein sorting (Vps) proteins some of which form complexes that directly recognize the ubiquitin moieties of RTKs. UBPY and AMSH in mammals, as well as Doa4 in yeast, are deubiquitinating enzymes (DUBs) that associate with class E Vps proteins on endosomes. Here I review the recently unveiled roles and regulatory mechanisms of these DUBs in the endosomal sorting of ubiquitinated cargo proteins. These findings suggest that RTK downregulation is controlled not only by ubiquitination but also by deubiquitination of RTKs as well as other endosomal proteins. Therefore, elucidating the entire functions and regulation of the endosomal DUBs potentially provides novel molecular targets for the treatment of cancer accompanied by overexpression or constitutive activation of RTKs.

Keywords: Deubiquitinating enzyme; deubiquitination; endosome; growth factor; protein sorting; receptor downregulation; receptor tyrosine kinase; ubiquitination

Document Type: Research article

Publication date: 2008-03-01

More about this publication?

• Due to the plethora of new approaches being used in modern drug discovery by the pharmaceutical industry, Current Drug Discovery Technologies has been established to provide comprehensive overviews of all the major modern techniques and technologies used in drug design and discovery. The journal is the forum for publishing both original research papers and reviews describing novel approaches and cutting edge technologies used in all stages of drug discovery. The journal addresses the multidimensional challenges of drug discovery science including integration issues of the drug discovery process.
  
  Current Drug Discovery Technologies is an essential journal for all scientists and research managers involved in drug discovery who wish to keep abreast of all the modern techniques and technologies used in drug discovery.

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