Fig. 8.

Keratin 8 is normally downregulated in the lens after fiber cell differentiation, but is retained in the Sip1 cKOs. Prior studies show Keratin 8 is highly expressed in the limbus, confirmed here (A). Keratin 8 is absent from the adult lens (B); but is expressed in the embryonic head ectoderm at E9.5 (C). At the mRNA level (D), Keratin 8 is significantly increased 41 fold (+61/-25; p-value = 0.00004), while Keratin 18 is increased 5 fold (+7/-3; p-value = 0.004). In both the wild type (E) and Sip1 cKO (F), Keratin 8 protein continues to be expressed at E10.5. Expression of Keratin 8 in the wild type is decreased by E12.5 (G) and undetected by E14.5 (I) and E16.5 (K), but expression persists in the peripheral epithelium/transition zone of the Sip1 cKOs at these stages (H, J, L). Abbreviations: ce, corneal epithelium; L, limbus; he, head ectoderm; lp, lens placode; ov, optic vesicle; lv, lens vesicle; r, early retina; e, lens epithelium; pf, posterior fiber cells; f, lens fiber cells; tz, lens transition zone. Prime panels (e.g. A′) show Keratin 8 expression (Red) merged with nuclei (DRAQ5, Blue). Scale bar = 61μm.