Ceramides form the backbone of all sphingolipids, and they have emerged as important regulators and mediators of cellular stress responses. Recently, however, significant complexity has arisen in ceramide metabolism and biology. Therefore, the long-term goal of this proposal is to understand specific pathways of ceramide metabolism involved in cell stress responses. Recent work in our laboratory has focused on a newly identified family of enzymes; namely ceramide synthases (CerS), which demonstrate selective preferences for the fatty acyl chains that they incorporate into ceramide. In addition, very recent and exciting work in our laboratory using proteomic approaches has led us to discover CerS-interacting proteins, and one of the most credible and exciting of these proteins is the long chain fatty acyl CoA synthetase (ACSL5). In compelling preliminary data, we demonstrate that this interaction defines a novel pathway of ceramide metabolism by which ACSL5 provides the long chain fatty acids to acylate ceramides at the 1 position to generate O-acylceramides. We also demonstrate that this likely occurs by the diacylglycerol acyltransferase DGAT2. Evidence strongly suggests storage of O-acylceramides in lipid droplets (LD), and functionally, this causes sequestration of ceramide in a pool that is biologically inaccessible for regulation of cell death pathways. This proposal, therefore, addresses the hypothesis that Ceramide is metabolized to O-acylceramide by a previously unappreciated ACSL5/DGAT2 dependent mechanism and stored in LD and that this metabolic pathway is a key regulator of ceramide-mediated biologies. To test this hypothesis we propose the following specific aims:
Aim 1. Define a novel pathway of ceramide metabolism to O- acylceramide by ACSL5/DGAT2 dependent mechanism.
Aim 2. Define a role for O- acylceramides (in LD) in the regulation of ceramide-mediated responses.
Aim 3. Determine the mechanism of CerS/ACSL5 protein-protein interaction. Taken together these studies will uncover a novel ceramide metabolic pathway to O-acylceramide by ACSL5 and DGAT2 with important implications for cell regulation.

Public Health Relevance

This proposal seeks to uncover a novel metabolic pathway for ceramide to O- acylceramide by the addition of a fatty acid, and its consequent storage in lipid droplets within cells thus making it inaccessible for its biologic activity in cell stress response and cell death.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
2R01GM097741-18
Application #
8961641
Study Section
Biochemistry and Biophysics of Membranes Study Section (BBM)
Program Officer
Chin, Jean
Project Start
1998-07-01
Project End
2019-06-30
Budget Start
2015-08-01
Budget End
2016-06-30
Support Year
18
Fiscal Year
2015
Total Cost
Indirect Cost
Name
State University New York Stony Brook
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
804878247
City
Stony Brook
State
NY
Country
United States
Zip Code
11794
Espaillat, Mel Pilar; Kew, Richard R; Obeid, Lina M (2017) Sphingolipids in neutrophil function and inflammatory responses: Mechanisms and implications for intestinal immunity and inflammation in ulcerative colitis. Adv Biol Regul 63:140-155
Hernández-Corbacho, María José; Salama, Mohamed F; Canals, Daniel et al. (2017) Sphingolipids in mitochondria. Biochim Biophys Acta 1862:56-68
Dupre, Tess V; Doll, Mark A; Shah, Parag P et al. (2017) Inhibiting glucosylceramide synthase exacerbates cisplatin-induced acute kidney injury. J Lipid Res 58:1439-1452
Senkal, Can E; Salama, Mohamed F; Snider, Ashley J et al. (2017) Ceramide Is Metabolized to Acylceramide and Stored in Lipid Droplets. Cell Metab 25:686-697
Snider, Ashley J; Bialkowska, Agnieszka B; Ghaleb, Amr M et al. (2016) Murine Model for Colitis-Associated Cancer of the Colon. Methods Mol Biol 1438:245-54
Carroll, Brittany L; Pulkoski-Gross, Michael J; Hannun, Yusuf A et al. (2016) CHK1 regulates NF-?B signaling upon DNA damage in p53- deficient cells and associated tumor-derived microvesicles. Oncotarget 7:18159-70
Xu, Ruijuan; Wang, Kai; Mileva, Izolda et al. (2016) Alkaline ceramidase 2 and its bioactive product sphingosine are novel regulators of the DNA damage response. Oncotarget 7:18440-57
Wang, K; Xu, R; Snider, A J et al. (2016) Alkaline ceramidase 3 deficiency aggravates colitis and colitis-associated tumorigenesis in mice by hyperactivating the innate immune system. Cell Death Dis 7:e2124
Yi, Jae Kyo; Xu, Ruijuan; Jeong, Eunmi et al. (2016) Aging-related elevation of sphingoid bases shortens yeast chronological life span by compromising mitochondrial function. Oncotarget 7:21124-44
Sundaram, Kumaran; Mather, Andrew R; Marimuthu, Subathra et al. (2016) Loss of neutral ceramidase protects cells from nutrient- and energy -deprivation-induced cell death. Biochem J 473:743-55

Showing the most recent 10 out of 28 publications