Differentiated hamster sebocytes exhibit apoptosis‐resistant phenotype by the augmentation of intracellular calcium level in vitro

Abstract

Sebaceous glands play important roles in the maintenance of the skin barrier function by secreting sebum onto the skin surface. In our study, we demonstrated that differentiated hamster sebocytes (DHS) exhibited apoptosis resistance and the loss of Ca 2+ influx against a calcium ionophore, A23187 treatment, which induced both apoptosis and Ca 2+ influx in undifferentiated hamster sebocytes (unDHS). The Fluo-3-related signal of intracellular Ca 2+ in the DHS was higher than that in unDHS and was sustained even though there was a depletion of Ca 2+ from the culture medium.Furthermore, the intracellular Ca 2+ chelator, BAPTA-AM, was found to decrease the Ca 2+ signal in the DHS, which induced apoptosis. Thus, these results provide novel evidence that the cell differentiation-dependent increase in store-operated Ca 2+ release is associated with apoptosis resistance in the DHS. Moreover, these findings should accelerate the understanding of the mechanisms of sebogenesis and/or sebum production and secretion under physiological conditions.Abbreviations: TG, triacylglycerol; DHS, differentiated hamster sebocytes; unDHS, undifferentiated hamster sebocytes; BAPTA-AM, 1,2-bis (2-aminophenoxy) ethane-N,N,N′,N′-tetraacetic acid tetrakis acetoxymethyl ester; FITC, fluorescein isothiocyanate; PI, propidium iodide; PS phosphatidylserine; 2-APB, 2-aminoethyl diphenylborinate.

Effects of Extracellular Calcium and 1,25 dihydroxyvitamin D3 on Sebaceous Gland Cells In vitro and In vivo

“…In addition, α-melanocyte-stimulating hormone increases lipogenesis in SZ95 sebocytes (19,20), and regulates icCa 2+ levels, in parallel (19). Moreover, icCa 2+ chelation induced apoptosis in hamster sebocytes (21). Although keratinocytes and sebocytes are both epithelial cells, they are antipodes regarding their mode of differentiation, as shown in our previous studies (22,23).…”

“…SZ95 sebocytes express the vitamin D receptor (VDR) at mRNA and protein levels and possess all enzymes required for the synthesis and metabolism of 1,25(OH)2D3, the biologically active metabolite of vitamin D (25). An anti-inflammatory effect of 1,25(OH)2D3 on human sebocytes has been shown, as 1,25(OH)2D3 reduced interleukin (IL)-6 and IL-8 as well as metalloproteinase-9 expression and secretion (25,26) at ecCa 2+ levels of 0.4 mM (21). Since neither the exact "Ca 2+ switch" concentration in human sebocytes nor the ecCa 2+ levels/1,25(OH)2D3 interaction on sebocyte differentiation, lipogenesis, and apoptosis are known, it was the aim of our in vitro study to elucidate these events.…”

A practical guide for the study of human and murine sebaceous glands in situ

“…These are lipid‐laden and feature pyknotic nuclei before cell rupture and dispersion of the cell contents, completing the process of holocrine secretion , a unique method of secretion employed by the SG . The mechanisms of holocrine secretion are still hypothetical, but include the lysis of sebocytes by hydrolytic enzymes within lysosomes , apoptosis‐induced cell lysis and/or the release of sebum via an ABCB1 transporter‐dependent mechanism .…”

“…Therefore, we also encourage the standardisation of histomorphometric techniques to evaluate changes in SG size/activities, thus hoping to improve the inter-observer reproducibility of published histological data, for example in trials of SG disorders (31). The techniques described here are transferable to isolated/specialised SGs and are relevant to other SG research models, for example hamster SGs and cultured sebocytes (24,25,32).…”

“…The SG is one of the most intriguing mammalian skin structures as it can serve as a model for studying numerous central life sciences issues, for example in cell biology and in skin, lipid or hormone research . Moreover, the SG is unique in at least two ways: its main cellular component, sebocytes, is of epithelial origin, yet engage in lipid production and metabolism, a feature usually associated with adipocytes; and sebum is produced by holocrine secretion, that is, via an unusual mode of cell suicide that sebocytes undergo .…”