Ceramide induces expression of the senescence histochemical marker, β-galactosidase, in human fibroblasts

Abstract

We recently showed that ceramide is elevated in senescence and that when administered to low-passage cells induces biochemical changes characteristic of senescence. The in situ histochemical marker β-galactosidase (β-Gal) has provided an important tool in the study of cellular senescence. We investigated the ability of ceramide to induce the expression of β-Gal and correlated this with cell proliferation. We find that d-e-C 6-ceramide, induces the expression of acidic β-Gal in fetal lung-derived Wi-38 human diploid fibroblasts. Our results show that this induction is: (1) time and concentration dependent; and (2) reversible upon ceramide removal. We also find that concomitant with the onset of β-Gal staining, DNA synthesis is blocked. These conditions are reversible. The induction of β-Gal expression is specific to C 6-ceramide. We discuss a potential role of β-Gal in the regulation of senescence. Although signal transduction of senescence is still not fully understood, this new evidence strengthens the hypothesis that ceramide plays a key role in signaling down stream biochemical changes in cellular senescence.