Perlecan expression influences the keratin 15-positive cell population fate in the epidermis of aging skin.

The epidermis is continuously renewed by stem cell proliferation and differentiation. Basal keratinocytes append the dermal-epidermal junction, a cell surface-associated, extracellular matrix that provides structural support and influences their behaviour. It consists of laminins, type IV collagen, nidogens, and perlecan, which are necessary for tissue organization and structural integrity.

Cell surface proteoglycans syndecan-1 and -4 bind overlapping but distinct sites in laminin α3 LG45 protein domain.

Keratinocyte migration during epidermal repair depends on interactions between cellular heparan sulfate proteoglycan receptors, syndecan-1 and -4, and the C-terminal globular domains (LG45) of the extracellular matrix protein laminin 332. This study investigates the molecular basis of the binding specificity of the syndecan-1 and -4 receptors expressed by human keratinocytes. We used site-directed mutagenesis to alter a recombinant LG45 protein by substituting the most critical basic residues with glutamine.