title: Phospholemman expression in extraglomerular mesangium and afferent arteriole of the juxtaglomerular apparatus.
abstract: The molecular mechanisms with which the juxtaglomerular apparatus accomplishes its twin functions, acute regulation of glomerular blood flow and secretion of renin, are still not clearly understood. Least understood is the role of the extraglomerular mesangial (EM) cells, also known as lacis or Goormaghtigh cells, which lie sandwiched between the macula densa and the afferent and efferent arterioles. Here, we report that immunoreactivity for phospholemman (FXYD1), a single-span membrane protein homologous to the gamma (gamma) sub-unit of the Na,K-ATPase, is found in the kidney in EM cells with the Na,K-ATPase beta2-subunit and in cortical blood vessels and the afferent arteriole with Na,K-ATPase alpha2 and beta2. Phospholemman's distribution in EM cells is distinct from that of the Na,K-ATPase gamma-subunit, which is found on the basolateral surface of macula densa cells with Na,K-ATPase alpha1 and beta1. Phospholemman is a major kinase target, and its location in the juxtaglomerular apparatus suggests that it is involved in tubuloglomerular feedback.
authors.affiliation: Laboratory of Membrane Biology, Neuroscience Center, Massachusetts General Hospital, Charlestown, Massachusetts 02129, USA.
authors.forename: Randall K
authors.initials: RK
authors.lastname: Wetzel
authors.forename: Kathleen J
authors.initials: KJ
authors.lastname: Sweadner
mesh_terms: D000818:Animals; D001160:Arterioles / Q000378:metabolism*; D015870:Gene Expression; D005920:Glomerular Mesangium / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D007606:Juxtaglomerular Apparatus / Q000098:blood supply* / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism*; D051381:Rats; D012079:Renal Circulation; D015398:Signal Transduction; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
chemical_list: D008565:Membrane Proteins; D010750:Phosphoproteins; C069141:phospholemman; D000254:Sodium-Potassium-Exchanging ATPase