Lhx2 differentially regulates Sox9, Tcf4 and Lgr5 in hair follicle stem cells to promote epidermal regeneration after injury

Abstract

SUMMARYThe Lhx2 transcription factor plays essential roles in morphogenesis and patterning of ectodermal derivatives as well as in controlling stem cell activity. Here, we show that during murine skin morphogenesis, Lhx2 is expressed in the hair follicle (HF) buds, whereas in postnatal telogen HFs Lhx2 + cells reside in the stem cell-enriched epithelial compartments (bulge, secondary hair germ) and co-express selected stem cell markers (Sox9, Tcf4 and Lgr5). Remarkably, Lhx2+ cells represent the vast majority of cells in the bulge and secondary hair germ that proliferate in response to skin injury. This is functionally important, as wound reepithelization is significantly retarded in heterozygous Lhx2 knockout (+/-) mice, whereas anagen onset in the HFs located closely to the wound is accelerated compared with wild-type mice. Cell proliferation in the bulge and the number of Sox9 + and Tcf4 + cells in the HFs closely adjacent to the wound in Lhx2 +/-mice are decreased in comparison with wild-type controls, whereas expression of Lgr5 and cell proliferation in the secondary hair germ are increased. Furthermore, acceleration of wound-induced anagen development in Lhx2 +/-mice is inhibited by administration of Lgr5 siRNA. Finally, Chip-on-chip/ChIP-qPCR and reporter assay analyses identified Sox9, Tcf4 and Lgr5 as direct Lhx2 targets in keratinocytes. These data strongly suggest that Lhx2 positively regulates Sox9 and Tcf4 in the bulge cells, and promotes wound re-epithelization, whereas it simultaneously negatively regulates Lgr5 in the secondary hair germ and inhibits HF cycling. Thus, Lhx2 operates as an important regulator of epithelial stem cell activity in the skin response to injury.

Transcription Factor SOX9 Plays a Key Role in the Regulation of Visual Cycle Gene Expression in the Retinal Pigment Epithelium

“…The direct relations reported in the RPE are regulation of Mitf and Otx2 by ␤-catenin (14) and regulation of Rdh5 by OTX2 (16). The direct relations reported in non-RPE cells are regulation of MITF by SOX9 in human skin melanocytes (67) and regulation of Sox9 by LHX2 in mouse skin keratinocytes (26) (Fig. 9).…”

“…The antibodies for SOX9, OTX2, and SOX10 were used in ChIP in our previous studies (17,32). The antibody for LHX2 was used in ChIP with mouse keratinocytes (26), and its specificity was confirmed (43). ChIP precipitates and diluted input (1:50) were analyzed by qPCR with primers at different genomic locations of RPE65, RLBP1, and RGR (supplemental Table S2).…”

“…In the RPE, however, the expression and function of LHX2 has not been described. Of interest, Sox9 has been identified as a direct target of LHX2 in mouse skin keratinocytes, suggesting a possible direct link between the two factors (26).…”

Cofactors of LIM Domains Associate with Estrogen Receptor α to Regulate the Expression of Noncoding RNA H19 and Corneal Epithelial Progenitor Cell Function

“…CLIMs Act through Unique Mechanisms to Modulate Progenitor Cells in Different Tissues-CLIMs play a number of roles in progenitor cell maintenance: they promote quiescence in hematopoietic stem cells (49), maintain hair follicle stem cells in the epidermis through interaction with LHX2 (7,34,42,50), and maintain the proliferative potential of basal stem cells, acting upstream of Fgfr2 in mammary epithelium (15). In our studies characterizing CLIM regulation of corneal epithelial progenitor cell maintenance, we did not find evidence for CLIM binding to the proximal Fgfr2 promoter, and motif analysis suggests that CLIM acts independently of LHX factors in the cornea.…”

The role of Nfix in the development of the embryonic and postnatal cerebral cortex

“…For example, male sex determination is coordinated via the synergistic action of Sry and Sf1 on Sox9 enhancer elements within developing Sertoli cells (Sekido and Lovell-Badge 2008). Lhx2 has also been shown to regulate Sox9 expression within hair follicle stem cells (Mardaryev et al 2011), whereas Notch1 signaling promotes Sox9 expression during chondrogenesis (Haller et al 2011). During cortical development, SHH too has been shown to induce Sox9 expression, although whether this effect is direct or indirect remains unclear .…”