title: Protein phosphatase 4--from obscurity to vital functions.
abstract: Protein phosphatase 4 (Ppp4) is a ubiquitous serine/threonine phosphatase in the PPP family that is now recognised to regulate a variety of cellular functions independently of protein phosphatase 2A (PP2A). Regulatory subunits (R1 and R2) have been identified in mammals that interact with the catalytic subunit of Ppp4 (Ppp4c) and control its activity. Ppp4c-R2 complexes play roles in organelle assembly; not only are they essential for maturation of the centrosome, but they are also involved in spliceosomal assembly via interaction with the survival of motor neurons (SMNs) complex. Several cellular signalling routes, including NF-kappaB and the target of rapamycin (TOR) pathways appear to be regulated by Ppp4. Emerging evidence indicates that Ppp4 may play a role in the DNA damage response and that Ppp4c-R1 complexes decrease the activity of a histone deacetylase, implicating Ppp4 in the regulation of chromatin activities. Antitumour agents, cantharidin and fostriecin, potently inhibit the activity of Ppp4. Orthologues of mammalian Ppp4 subunits in Saccharomyces cerevisiae confer resistance to the anticancer, DNA-binding drugs, cisplatin and oxaliplatin.
authors.affiliation: Medical Research Council Protein Phosphorylation Unit, School of Life Sciences, MSI/WTB Complex, University of Dundee, Dow Street, Dundee DD1 5EH, UK. p.t.w.cohen@dundee.ac.uk
authors.forename: Patricia T W
authors.initials: PT
authors.lastname: Cohen
authors.forename: Amanda
authors.initials: A
authors.lastname: Philp
authors.forename: Cristina
authors.initials: C
authors.lastname: Vázquez-Martin
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D002467:Cell Nucleus / Q000378:metabolism; D006801:Humans; D015388:Organelles / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D054648:Protein Phosphatase 2; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D000970:Antineoplastic Agents; D021122:Protein Subunits; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2; C080406:protein phosphatase 4