ARHGAP29 promotes keratinocyte proliferation and migration in vitro and is dispensable for in vivo wound healing.

Background: RhoA GTPases play critical roles in actin cytoskeletal remodeling required for controlling a diverse range of cellular functions including cell proliferation, adhesion, migration and changes in cell shape, all required for cutaneous wound healing. RhoA cycles between an active GTP-bound and an inactive GDP-bound form, a process regulated by guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs). ARHGAP29 is a GAP expressed in skin keratinocytes and is decreased in the absence of interferon regulator factor 6, a critical regulator of cell proliferation, migration, and wound healing. However, the role for ARHGAP29 in keratinocyte biology is unknown.

Results: We generated ARHGAP29 knockdown keratinocyte cell lines and show they displayed increased filamentous actin, phospho-myosin regulatory light chain, cell area and population doubling time. Furthermore, we found that ARHGAP29 knockdown keratinocytes displayed significant delays in scratch wound closure in both single and collective cell migration conditions; these delays were rescued by both adding back ARHGAP29 or adding a ROCK inhibitor to ARHGAP29 knockdown cells. In vivo, however, Arhgap29 heterozygotes or keratinocyte-specific knockouts showed on-time wound healing.

Conclusions: These data demonstrate that ARHGAP29 is required for keratinocyte morphology, proliferation and migration in vitro but is dispensable during wound healing in vivo.