Fig 2: NM2 isoforms have selective expression and localization pattern with actin filaments in the renal tubules. Confocal analysis of sections stained for phalloidin and NM2 isoforms showed that NM2 isoforms did not colocalize with all the filamentous actin structures in the tubules. Myh9 colocalized with actin filaments on the apical membrane (A–C, arrowhead). Myh10 (D–F) and Myh14 (G–I) colocalized with actin filaments on both the apical (arrowhead) and basolateral membranes (arrow). NM2 isoforms appeared as punctate structures or short filaments on the membrane. Sections were mounted with vectashield containing DAPI to stain the nucleus (blue; C, F & I). Scale bar = 10 µm.

Fig 3: Myh10 and Myh14 isoforms show unique expression and localization pattern in the collecting duct. Kidney sections were stained with Aqp2 to identify the collecting duct segment and costained for the NM2 isoforms. Analysis showed that Myh9 (A–C) was not present in the collecting duct, Myh9 staining was present in the adjacent tubule (arrowhead). Myh10 (D–F) was the most abundant of the isoforms expressed in the collecting duct and localized to apical (arrowhead) and basolateral membrane as well as cell–cell adhesions. Myh14 (G–I) expression in the collecting duct was limited to the apical membranes (arrowhead) of cells not expressing Aqp2 (intercalated cells). Sections were mounted with vectashield containing DAPI to stain the nucleus (blue; C, F, and I). Scale bar = 10 µm.

Fig 4: Myh10 and Myh14 are the NM2 isoforms expressed in the proximal tubular segment. Confocal fluorescence microscopy of the adult mouse kidney sections stained for megalin (proximal tubule marker) and one of the NM2 isoforms revealed that Myh10 and Myh14 are the prominent isoforms of NM2 in the proximal tubules. Myh9 (red) is not expressed in the megalin (green)-positive proximal tubules (arrowheads, A–F); however, Myh9 expression is present in the adjacent tubules and the glomerulus (arrows, D–F). Myh10 localized to apical (arrowhead) and basolateral (arrow) membranes in the megalin-positive proximal tubular segments (G–I). Myh14 was expressed in the megalin-positive tubules on the apical membrane (arrowhead); punctate structures were also observed on the basolateral membrane and within the epithelial cells (J–L). The majority of Myh10 and Myh14 does not colocalize with megalin on the apical membrane, and appear to be above the megalin staining on the membrane. However, there are a few regions (microdomains) on the apical membrane (yellow arrowhead, I&L) where we observe partial colocalization. Sections were mounted with vectashield containing DAPI to stain the nuclei (blue; C, F, I & L). Scale bar = 10 µm.

Fig 5: Myh9 and Myh10 are the NM2 proteins expressed in the thick ascending limb of the loop of Henle segment. Confocal fluorescence microscopy of the adult mouse kidney sections stained for uromodulin (TAL marker) along with the NM2 proteins individually revealed that Myh9 and Myh10 are the major NM2 proteins in TAL segment of the Loop of Henle tubules. Myh9 (red) is highly expressed in the majority of the uromodulin (green) TAL tubules, with strong localization on the apical membrane (A–C, arrowhead). Myh10 localized to the apical (arrowhead) and basolateral membranes (arrow) in most of the uromodulin-positive TAL segments (D–F). Myh14 was not expressed in the TAL tubules, although several of the adjacent uromodulin-negative tubules expressed Myh14 (G–I). Sections were mounted with vectashield containing DAPI to stain the nucleus (blue; C, F & I). Scale bar = 10 µm.