Interferon regulatory factor 6 is required for proper wound healing in vivo

Abstract

Background Van der Woude syndrome (VWS) is the most common form of syndromic orofacial cleft caused predominantly by mutations in Interferon Regulatory Factor 6 (IRF6). We previously reported that individuals with VWS have increased risk of wound healing complications following cleft repair compared with individuals with nonsyndromic orofacial clefts (nonsyndromic cleft lip and palate—NSCLP). In vitro, absence of IRF6 leads to impaired keratinocyte migration and embryonic wound healing. However, there is currently no data on tissue repair in adult animals and cells with reduced levels of IRF6 like in VWS. Results Excisional wounds of Irf6+/− and wild‐type animals were analyzed 4 and 7 days post‐wounding. Although all wounds were reepithelialized after 7 days, the epidermal and wound volume of repaired wounds was larger in Irf6+/−. These data were supported by increased keratinocyte proliferation in the neoformed epidermis and a less mature granulation tissue with increased cytokine levels. This effect was not cell autonomous, as Irf6+/− neonatal keratinocytes in vitro did not exhibit defects in scratch wound closure or proliferation. Keratinocytes from individuals with VWS also migrated similarly to keratinocytes from NSCLP individuals. Conclusions These data support a role for IRF6 in wound healing by regulating keratinocyte proliferation, granulation tissue maturation, and cytokine levels.

A Novel Van der Woude Syndrome-Causing IRF6 Variant Is Subject to Incomplete Non-sense-Mediated mRNA Decay Affecting the Phenotype of Keratinocytes

“…These circumstances reflect the situation in our VWS case: (1) the aberrant IRF6 transcript contains an NMD-triggering PTC in the third last exon (exon 7) of IRF6 (Figure 2) and (2) the IRF6_VWS protein still harbors some physiological transcription factor activity as it is able to induce the endogenous transcription factors GRHL3, KLF4, and OVOL1 as well as IRF6 itself (Figure 8). There is increasing evidence that a IRF6 threshold level is required for its full physiological activity during craniofacial development (Ingraham et al, 2006;Richardson et al, 2006), neurulation (Kousa et al, 2019), and keratinocyte migration and wound healing (Rhea et al, 2020). Therefore, the efficiency of the NMD process might be a crucial modulator of the clinical manifestation of VWS, a condition often associated with truncating IRF6 variants (de Lima et al, 2009).…”

Lack of IRF6 Disrupts Human Epithelial Homeostasis by Altering Colony Morphology, Migration Pattern, and Differentiation Potential of Keratinocytes

“…IRF6 might represent such a candidate gene. Indeed, particular wound healing defects like reduced speed and directionality during wound re-epithelialization, as well as impaired maturation of the granulation tissue, have been described in embryonic Irf6 – / – keratinocytes in vitro ( Biggs et al, 2014 ) and in Irf6 + / – mice in vivo ( Rhea et al, 2020 ), respectively. These observations might also provide the molecular rationale for the increased likelihood of wound healing complications experienced by VWS patients harboring IRF6 variants in comparison to non-syndromic cleft patients ( Jones et al, 2010 ).…”

The dynamics of epidermal stratification during post‐larval development in zebrafish

“…68 This is a fine controlled process at the molecular level. 69 A similar process takes place in the wounded epidermis of grown zebrafish. 70 Keratinocytes migrate to the wound from the adjoining epidermis.…”

“…During this process, cell‐cell junctions are lost, cells change shape, and motility is enhanced 68 . This is a fine controlled process at the molecular level 69 . A similar process takes place in the wounded epidermis of grown zebrafish 70 .…”