title: System-wide immunohistochemical analysis of protein co-localization.
abstract: BACKGROUND
  The analysis of co-localized protein expression in a tissue section is often conducted with immunofluorescence histochemical staining which is typically visualized in localized regions. On the other hand, chromogenic immunohistochemical staining, in general, is not suitable for the detection of protein co-localization. Here, we developed a new protocol, based on chromogenic immunohistochemical stain, for system-wide detection of protein co-localization and differential expression.
  
  
  RESULTS
  In combination with a removable chromogenic stain, an efficient antibody stripping method was developed to enable sequential immunostaining with different primary antibodies regardless of antibody's host species. Sections were scanned after each staining, and the images were superimposed together for the detection of protein co-localization and differential expression. As a proof of principle, differential expression and co-localization of glutamic acid decarboxylase67 (GAD67) and parvalbumin proteins was examined in mouse cortex.
  
  
  CONCLUSIONS
  All parvalbumin-containing neurons express GAD67 protein, and GAD67-positive neurons that do not express parvalbumin were readily visualized from thousands of other neurons across mouse cortex. The method provided a global view of protein co-localization as well as differential expression across an entire tissue section. Repeated use of the same section could combine assessments of co-localization and differential expression of multiple proteins.
authors.affiliation: Department of Psychiatry, University of California San Diego, La Jolla, California, United States of America.
authors.forename: Minjung
authors.initials: M
authors.lastname: Kim
authors.forename: Virawudh
authors.initials: V
authors.lastname: Soontornniyomkij
authors.forename: Baohu
authors.initials: B
authors.lastname: Ji
authors.forename: Xianjin
authors.initials: X
authors.lastname: Zhou
mesh_terms: D000818:Animals; D064032:Calbindin 2; D002540:Cerebral Cortex / Q000166:cytology / Q000378:metabolism; D005968:Glutamate Decarboxylase / Q000378:metabolism; D007150:Immunohistochemistry / Q000379:methods*; D051379:Mice; D010320:Parvalbumins / Q000378:metabolism; D011485:Protein Binding; D021381:Protein Transport; D011506:Proteins / Q000378:metabolism*; D064030:S100 Calcium Binding Protein G
chemical_list: D064032:Calbindin 2; D010320:Parvalbumins; D011506:Proteins; D064030:S100 Calcium Binding Protein G; D005968:Glutamate Decarboxylase; C402565:glutamate decarboxylase 1