Fig. 1.

Glomeruli of diacylglycerol kinase-ε (Dgke) knockout (KO) mice have submicroscopic signs of endothelial impairment that worsen with age. A: representative light microscopy images of Dgke KO mice glomeruli compared with wild-type (WT) littermates at 6 wk of age. Dgke KO glomeruli are apparently normal and indistinguishable from WT controls. Hematoxylin and eosin (H&E), scale bars = 20 μm. B: on transmission electron microscopy (TEM), in the glomeruli of Dgke KOs, some capillaries show modest signs of endothelial stress with loss of fenestrae and swelling of the endothelial rim (black arrowheads; left). Segments of the glomerular basal membranes (GBMs) appear inspissated (black arrow, left) or duplicated for the interposition of appendices of mesangial cells (white arrows, left and inset). The epithelial compartment is relatively well preserved, and only minimal podocyte foot process effacement is observed (white arrowheads, left and inset). Notice the presence of fenestrae (black arrowheads, right) and the normal foot processes (white arrowheads, right and inset) in a WT littermate. Scale bars = 5 μm. Insets show boxed areas at higher magnification. C: quantification of the number of stressed endothelial cells per number of capillary loops examined. Values are means ± SE; n = 20 consecutive capillary loops form multiple glomeruli, with 2 mice per experimental group. D: urinary albumin-to-creatinine ratio (ACR) in 24-h urine of Dgke KO and WT mice. Values are means ± SE; n = 3 mice per group. ns, Nonsignificant. E: light microscopy images of Dgke KO mice glomeruli compared with WT littermates at 1 yr of age. Glomerular congestion and focal capillary obliteration (arrows) with thickening of the GBM (arrowheads) are detectable in some glomeruli of Dgke KOs compared with WT controls. Scale bars = 20 μm. Insets show boxed areas at higher magnification. F: TEM images of Dgke KO mice glomeruli compared with WT littermates at 1 yr of age. Swelling of the endothelial rim (black arrowheads) is frequently accompanied by mesangial interposition (white asterisks) and splitting of the basal membrane (white arrowhead), which are indicative of chronic glomerular repair. Scale bars = 1 μm. G: quantification of the number of stressed endothelial cells per number of capillary loops examined. Values are means ± SE; n = 20 consecutive capillary loops form multiple glomeruli, with 2 mice per experimental group. H: urinary ACR in 24-h urine of Dgke KO and WT mice. Values are means ± SE; n = 3 WT and 3 Dgke^−/− mice. P values were calculated by Student's t-test.