Dynamic changes in the functions of Klf5 in maturing mouse corneas revealed by the changes in its target genes at postnatal days 11 and 56

Purpose: Klf5 plays a critical role in the mouse ocular surface (Kenchegowda et al., 2011. Dev Biol. 356:5-18). Here, we compare wild-type (WT) and Klf5-conditional null (Klf5CN) corneal gene expression at postnatal day-11 (PN11) and PN56 to identify the Klf5-target genes. Methods: Gene expression was compared using Affymetrix microarrays with QPCR validation. Transient transfection assays examined the effect of Klf5 on selected target gene promoter activities. Whole-mount corneal immunofluorescent staining examined neovascularization and CD45+ macrophage influx. Results: Expression of 714 and 753 genes was increased, and 299 and 210 genes decreased in PN11 and PN56 Klf5CN corneas, respectively, with 366 concordant increases, 72 concordant decreases and 3 discordant changes. Canonical pathway analysis identified 35 and 34 significantly (p<0.001) enriched pathways at PN11 and PN56, respectively, with 24 common pathways. PN56 Klf5CN corneas shared 327 increases and 91 decreases with the previously described Klf4CN corneas (Swamynathan et al., 2008. IOVS 49:3360-70). Angiogenesis and immune response-related genes were affected consistent with lymphangiogenesis and macrophage influx in Klf5CN corneas, respectively. Expression of 1574 genes was increased and 1915 decreased, in the WT PN56 compared with PN11 corneas. Expression of many collagens, matrix metalloproteinases and other extracellular matrix associated genes decreased in WT corneas between PN11 and PN56, while that of solute carrier family members increased. Conclusions: Differences in PN11 and PN56 corneal Klf5-target genes reveal dynamic changes in Klf5 functions during corneal maturation. Klf4- and Klf5-target genes do not overlap, consistent with their non-redundant roles in the mouse cornea.

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Kenchegowda D, Harvey SA, Swamynathan S, Lathrop KL, Swamynathan SK