FIGURE 10:

Mitochondrial LDs are also present in uroplakin-KO urothelia. (A–C) Paraffin sections of (A) control, (B) UPII-KO, and (C) UPIIIa-KO mouse urothelia were stained using antibodies to UPIa, II, Ib, IIIa, and IIIb as indicated; note in C that UPIIIa-KO leads to the formation of cytoplasmic aggregates containing all the remaining uroplakin types (arrows). (D–G) TEM of UPIIIa-KO urothelial superficial cells showing the perinuclear accumulation of LD-containing mitochondria (stages I and II; * and **, respectively); some appear to be interacting with isolation membranes (arrowheads). (H1, H2) The quick-freeze deep-etch (QFDE) images of the apical surface of a UPIIIa-KO superficial cell (the E face) showing small patches of hexagonally packed 16-nm uroplakin particles, as well as a patch of abnormal 3–4-nm particles containing UPIa/II-Ib/IIIb (bracketed). (J1, J2) Immunogold EM of a UPII-KO superficial cell showing the UP-positive intramitochondrial LDs (*). (K) An occasional wild-type umbrella cell showing a mitochondrion containing a small intramitochondrial LD (white arrow). (L–Q) Paraffin sections of the UPIIIa-KO urothelium were double stained using antibodies to uroplakins and (L) PLIN2, (M) AIF and LC3, (N) PINK1, (O) N-BiP (ER stress), and (P) LAMP1. “Mer” denotes a merged image. (Q1, Q2) TUNEL assay for paraffin sections of (Q1) UPIIIa-KO and (Q2) UPII-KO urothelium. Note the colocalization of these UP-KO–related intramitochondrial LDs with markers of (L) lipid droplet, (M) mitochondria, (N) mitophagy, and (O) ER stress marker, but not with (M) markers for autophagy or (P) lysosome. Scale bars = 50 nm in H; 0.2 µm in E and F; 0.5 µm in D, G, J, and K; 10 µm in L–P; 50 µm in A–C and Q.