Restraint of Human Skin Fibroblast Motility, Migration, and Cell Surface Actin Dynamics, by Pannexin 1 and P2X7 Receptor Signaling

Abstract

Wound healing is a dynamic process required to maintain skin integrity and which relies on the precise migration of different cell types. A key molecule that regulates this process is ATP. However, the mechanisms involved in extracellular ATP management are poorly understood, particularly in the human dermis. Here, we explore the role, in human fibroblast migration during wound healing, of Pannexin 1 channels and their relationship with purinergic signals and in vivo cell surface filamentous actin dynamics. Using siRNA against Panx isoforms and different Panx1 channel inhibitors, we demonstrate in cultured human dermal fibroblasts that the absence or inhibition of Panx1 channels accelerates cell migration, increases single-cell motility, and promotes actin redistribution. These changes occur through a mechanism that involves the release of ATP to the extracellular space through a Panx1-dependent mechanism and the activation of the purinergic receptor P2X7. Together, these findings point to a pivotal role of Panx1 channels in skin fibroblast migration and suggest that these channels could be a useful pharmacological target to promote damaged skin healing.

Pannexin Channel Regulation of Cell Migration: Focus on Immune Cells

“…Consequently, ATP release and associated purinergic signaling play a key role during skin inflammation and wound healing ( 108 ). In particular, PANX1 is expressed in keratinocytes and fibroblasts from human and mice skin, as discussed below ( 98 , 105 , 109 – 111 ).…”

“…In the same line, PANX1 negatively regulates human dermal fibroblast migration when kept in monocultures. Indeed, fibroblasts lacking PANX1 or those treated with PANX1 channel blockers increase their speed of collective migration in wound healing assays, a similar but smaller response occurs when cells lack PANX3 ( 105 ). The decrease in cell migration during wound healing in fibroblasts is linked to decreased ATP release and activation of purinergic receptors.…”

“…The decrease in cell migration during wound healing in fibroblasts is linked to decreased ATP release and activation of purinergic receptors. Consequently, P2X 7 receptors blockade increases the speed of migration in human dermal fibroblasts ( 105 ). However, this last data should be considered carefully depending on the working model to be compared with, as the authors also report no effect over migration with P2X 7 blockade in murine dermal fibroblasts ( 105 ).…”

“…Consequently, P2X 7 receptors blockade increases the speed of migration in human dermal fibroblasts ( 105 ). However, this last data should be considered carefully depending on the working model to be compared with, as the authors also report no effect over migration with P2X 7 blockade in murine dermal fibroblasts ( 105 ). Additionally, in vivo experiments in a mice model reveal that PANX3 was required for proper wound healing ( 89 ).…”

“…This suggests that different models of study might require different purinergic receptors. In any case, PANX1- and PANX3-dependent ATP release was consistently associated with a decrease in the collective and single migration of dermal fibroblasts, a response that relies in reorganization of the actin cytoskeleton ( 105 ).…”