Fig. 7.

PERK promotes autophagy and survival in lactating mammary glands. Detection of P-PERK (A), LC3 (B), p62 (C), and BimEL and cleaved caspase-3 (D) in day 12 lactating mammary glands sections from control PERK^loxP/loxP and mammary gland-specific PERK knockout (PERK^Δ/Δ) mice was done by immunohistochemistry (A, B, and D) and immunofluorescence (C). (A) Images showing enhanced P-PERK staining in the control tissues along with strong staining in detaching (middle panels and insets) and luminal cells (arrow, lower panels), which is lost in PERK^Δ/Δ tissues. (B) Images showing enhanced LC3 staining (upper panels and insets) and detachment-induced LC3 expression (lower panels) in PERK^loxP/loxP control tissues, which is lost in PERK^Δ/Δ tissues. (C) Images showing enhanced p62 punctate staining in PERK^Δ/Δ versus control tissues. Insets show magnification to illustrate the accumulation of p62 in autophagosomes. Arrows show p62 punctate staining in both basal (arrowheads) and ECM-detached (arrow) cells in PERK^Δ/Δ tissues. (D) Upper and middle rows, images showing enhanced BimEL staining in PERK^Δ/Δ versus control tissues. Insets show magnification details. The middle panels show strong BimEL staining of PERK^Δ/Δ detached cells located within the lumen (arrows). Lower panels show cleaved caspase-3 staining in PERK^Δ/Δ and control tissues, which displayed more cellularity than the KO mammary epithelium. Numbers in the lower left corners are the means ± standard errors of the means (SEM) of the percentages of cleaved caspase-3-positive luminal cells per field; ∼1,000 total luminal cells were scored. Blue, hematoxylin and eosin (H&E) staining.