Decreased Galectin-3 and -7 Expressions in Old-Aged Skin and Their Differential Expression in Skin Equivalents

Peptide location fingerprinting reveals modification-associated biomarker candidates of ageing in human tissue proteomes

Although dysfunctional protein homeostasis (proteostasis) is a key factor in many age-related diseases, the untargeted identification of structurally modified proteins remains challenging. Peptide location fingerprinting is a proteomic analysis technique capable of identifying structural modification-associated differences in mass spectrometry (MS) data sets of complex biological samples. A new webtool (Manchester Peptide Location Fingerprinter), applied to photoaged and intrinsically aged skin proteomes, can relatively quantify peptides and map statistically significant differences to regions within protein structures. New photoageing biomarker candidates were identified in multiple pathways including extracellular matrix organisation (collagens and proteoglycans), protein synthesis and folding (ribosomal proteins and TRiC complex subunits), cornification (keratins) and hemidesmosome assembly (plectin and integrin α6β4). Crucially, peptide location fingerprinting uniquely identified 120 protein biomarker candidates in the dermis and 71 in the epidermis which were modified as a consequence of photoageing but did not differ significantly in relative abundance (measured by MS1 ion intensity). By applying peptide location fingerprinting to published MS data sets, (identifying biomarker candidates including collagen V and versican in ageing tendon) we demonstrate the potential of the MPLF webtool for biomarker discovery.

The Effects of the 3-OH Group of Kaempferol on Interfollicular Epidermal Stem Cell Fate

Background

Kaempferol (3,4′,5,7-tetrahydroxyflavone) is a flavonoid known to have a wide range of pharmacological activities. The 3-OH group in flavonoids has been reported to determine antioxidant activities.

Objective

We tested whether kaempferol can affect the expression of integrins and the stem cell fate of interfollicular epidermal stem cells.

Methods

Skin equivalent (SE) models were constructed, and the expression levels of stem cell markers and basement membrane-related antigens were tested. The immunohistochemical staining patterns of integrins, p63, and proliferating cell nuclear antigen (PCNA) were compared between kaempferol- and apigenin-treated SE models. Reverse transcription-polymerase chain reaction (RT-PCR) was used to evaluate the mRNA expression of integrins.

Results

Kaempferol increased the thickness of the epidermis when added to prepare SEs. In addition, the basal cells of kaempferol- treated SEs appeared more columnar. In the immunohistological study, the expression of integrins α6 and β1 and the numbers of p63- and PCNA-positive cells were markedly higher in the kaempferol-treated model. However, apigenin showed no effects on the formation of three-dimensional skin models. RT-PCR analysis also confirmed that kaempferol increased the expression of integrin α6 and integrin β1.

Conclusion

Our findings indicated that kaempferol can increase the proliferative potential of basal epidermal cells by modulating the basement membrane. In other words, kaempferol can affect the fate of interfollicular epidermal stem cells by increasing the expression of both integrins α6 and β1. These effects, in particular, might be ascribed to the 3-OH group of kaempferol.