title: Differential cellular expression of FXYD1 (phospholemman) and FXYD2 (gamma subunit of Na, K-ATPase) in normal human tissues: a study using high density human tissue microarrays.
abstract: FXYD proteins have been proposed to function as regulators of Na, K-ATPase function by lowering affinities of the system for potassium and sodium. However, their distribution in normal human tissues has not been studied. We have therefore used immunohistochemistry and semi-quantitative histomorphometric analysis to determine the relative expression at the protein level and distribution of FXYD1 (phospholemman) and FXYD2 (gamma subunit of Na, K-ATPase) in human Tissue MicroArrays (TMAs). Expression of FXYD1 was abundant in heart, kidney, placenta, skeletal muscle, gastric and anal mucosa, small intestine and colon. Lower FXYD1 expression was detected in uterine, intestinal and bladder smooth muscle, choroid plexus, liver, gallbladder, spleen, breast, prostate and epididymis. The tissue distribution of FXYD2 was less extensive compared to that of FXYD1. There was an abundant expression in kidney and choroid plexus and moderate expression in placenta, amniotic membranes, breast epithelium, salivary glands, pancreas and uterine endometrium. Weaker FXYD2 expression was detected in the adrenal medulla, liver, gallbladder, bladder and pancreas. The common denominator in the distribution of FXYD1 and FXYD2 was expression in highly active transport epithelia of the kidney, choroid plexus, placenta and salivary glands. This study reveals, in human tissues, the specific expression of FXYD proteins, which may associate with Na, K-ATPase in selected cell types and modulate its catalytic properties.
authors.affiliation: Physiological Laboratory, Department of Physiology, School of Biomedical Sciences, Faculty of Health and Life Sciences, University of Liverpool, Liverpool, UK.
authors.forename: Rachel V
authors.initials: RV
authors.lastname: Floyd
authors.forename: Susan
authors.initials: S
authors.lastname: Wray
authors.forename: Pablo
authors.initials: P
authors.lastname: Martín-Vasallo
authors.forename: Ali
authors.initials: A
authors.lastname: Mobasheri
mesh_terms: D000313:Adrenal Medulla / Q000378:metabolism; D001940:Breast / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D007150:Immunohistochemistry; D008099:Liver / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D009928:Organ Specificity; D014066:Palatine Tonsil / Q000378:metabolism; D010179:Pancreas / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics*; D010920:Placenta / Q000378:metabolism; D011247:Pregnancy; D012016:Reference Values; D012469:Salivary Glands / Q000378:metabolism; D012867:Skin / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000235:genetics*; D014599:Uterus / Q000378:metabolism
chemical_list: D008565:Membrane Proteins; D010750:Phosphoproteins; C069141:phospholemman; C416502:FXYD2 protein, human; D000254:Sodium-Potassium-Exchanging ATPase