Glucosylceramide accumulates preferentially in lamellar bodies in differentiated keratinocytes

• DOI: 10.1111/j.1365-2133.2004.06333.x
• Publication Date: 2005-03-17T21:43:06Z
• Authors: S. Hamanaka; S. Nakazawa; M. Yamanaka; Y. Uchida; F. Otsuka
• Keywords: Sphingolipid; Lamellar granule; Stratum granulosum; Lactosylceramide; Cuboidal Cell; Glycosphingolipid

Background Sphingolipids, e.g. ceramide (Cer), glucosylceramide (GlcCer) and sphingomyelin (SM), are important bulk constituents of plasma membranes in mammalian cells. In addition, these lipids also enriched certain intracellular organelles, as well the epidermal lamellar bodies (LBs) differentiating keratinocytes (KCs). Epidermal Cer, which comprises a heterogeneous family at least 10 members, is key component stratum corneum (SC) lipids, regulates permeability barrier function. Levels GlcCer, but not SM, significantly increase during differentiation, then both GlcCer SM enzymatically hydrolysed to Cer just above transition from granulosum SC. Objectives To determine: (i) whether contained different pools, i.e. membrane fraction or LB fraction, has metabolic fates; (ii) specific molecular species localize distinct subcellular pools. Methods study fate fractions we first ascertained full spectrum present cultured normal human KCs (CHK) differentiated condition shown vivo epidermis. were analysed CHK using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Next, was studied by pulse-labelling with L-[14C]-serine. Results The undifferentiated comprised B NS (or 2), contain nonhydroxy fatty acid (FA) amide-linked FA, while displayed further heterogeneity including presence acylGlcCer acylCer. fates sphingolipids determined. level decreased over 2 days plateaued between 3 5 following for 24 h. As declined, (Cer 2) increased similar time-dependent manner. contrast, acylCer continuously parallel this experimental period. Conclusions Distinct pools segregated those that either hydrolysable nonhydrolysable KCs. We assume latter pool appears be enriched, sequestrates other cellular fractions.