title: Acetylcholine content and viability of cholinergic neurons are influenced by the activity of protein histidine phosphatase.
abstract: BACKGROUND
  The first mammalian protein histidine phosphatase (PHP) was discovered in the late 90s of the last century. One of the known substrates of PHP is ATP-citrate lyase (ACL), which is responsible--amongst other functions--for providing acetyl-CoA for acetylcholine synthesis in neuronal tissues. It has been shown in previous studies that PHP downregulates the activity of ACL by dephosphorylation. According to this our present work focused on the influence of PHP activity on the acetylcholine level in cholinergic neurons.
  
  
  RESULTS
  The amount of PHP in SN56 cholinergic neuroblastoma cells was increased after overexpression of PHP by using pIRES2-AcGFP1-PHP as a vector. We demonstrated that PHP overexpression reduced the acetylcholine level and induced cell death. The acetylcholine content of SN56 cells was measured by fast liquid chromatography-tandem mass spectrometry method. Overexpression of the inactive H53A-PHP mutant also induced cell damage, but in a significantly reduced manner. However, this overexpression of the inactive PHP mutant did not change the acetylcholine content of SN56 cells significantly. In contrast, PHP downregulation, performed by RNAi-technique, did not induce cell death, but significantly increased the acetylcholine content in SN56 cells.
  
  
  CONCLUSIONS
  We could show for the first time that PHP downregulation increased the acetylcholine level in SN56 cells. This might be a potential therapeutic strategy for diseases involving cholinergic deficits like Alzheimer's disease.
authors.affiliation: Institut fuer Pharmazeutische und Medizinische Chemie, Westfaelische Wilhelms-Universitaet, Muenster, Germany.
authors.forename: Anna
authors.initials: A
authors.lastname: Eißing
authors.forename: Daniel
authors.initials: D
authors.lastname: Fischer
authors.forename: Ilka
authors.initials: I
authors.lastname: Rauch
authors.forename: Anne
authors.initials: A
authors.lastname: Baumann
authors.forename: Nils-Helge
authors.initials: NH
authors.lastname: Schebb
authors.forename: Uwe
authors.initials: U
authors.lastname: Karst
authors.forename: Karsten
authors.initials: K
authors.lastname: Rose
authors.forename: Susanne
authors.initials: S
authors.lastname: Klumpp
authors.forename: Josef
authors.initials: J
authors.lastname: Krieglstein
mesh_terms: D000105:Acetyl Coenzyme A / Q000378:metabolism; D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000502:physiology*; D059329:Cholinergic Neurons / Q000378:metabolism*; D051379:Mice; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D010766:Phosphorylation; D014407:Tumor Cells, Cultured
chemical_list: D000105:Acetyl Coenzyme A; D010744:Phosphoric Monoester Hydrolases; D000109:Acetylcholine