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Alkaline Ceramidase 3 Deficiency Results in Purkinje Cell Degeneration and Cerebellar Ataxia Due to Dyshomeostasis of Sphingolipids in the Brain.

Wang K, Xu R, Schrandt J, Shah P, Gong YZ, Preston C, Wang L, Yi JK, Lin CL, Sun W, Spyropoulos DD, Rhee S, Li M, Zhou J, Ge S, Zhang G, Snider AJ, Hannun YA, Obeid LM, Mao C - PLoS Genet. (2015)

Bottom Line: However, mechanisms that maintain the homeostasis of these bioactive sphingolipids in the brain remain unclear.Acer3 knockout causes an age-dependent accumulation of various ceramides and C18:1-monohexosylceramide and abolishes the age-related increase in the levels of sphingosine and S1P in the brain; thereby resulting in Purkinje cell degeneration in the cerebellum and deficits in motor coordination and balance.Our results indicate that Acer3 plays critically protective roles in controlling the homeostasis of various sphingolipids, including ceramides, sphingosine, S1P, and certain complex sphingolipids in the brain and protects Purkinje cells from premature degeneration.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, Stony Brook University, Stony Brook, New York, United States of America; Stony Brook Cancer Center, Stony Brook, New York, United States of America; Department of Hepatobiliary Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, China.

ABSTRACT
Dyshomeostasis of both ceramides and sphingosine-1-phosphate (S1P) in the brain has been implicated in aging-associated neurodegenerative disorders in humans. However, mechanisms that maintain the homeostasis of these bioactive sphingolipids in the brain remain unclear. Mouse alkaline ceramidase 3 (Acer3), which preferentially catalyzes the hydrolysis of C18:1-ceramide, a major unsaturated long-chain ceramide species in the brain, is upregulated with age in the mouse brain. Acer3 knockout causes an age-dependent accumulation of various ceramides and C18:1-monohexosylceramide and abolishes the age-related increase in the levels of sphingosine and S1P in the brain; thereby resulting in Purkinje cell degeneration in the cerebellum and deficits in motor coordination and balance. Our results indicate that Acer3 plays critically protective roles in controlling the homeostasis of various sphingolipids, including ceramides, sphingosine, S1P, and certain complex sphingolipids in the brain and protects Purkinje cells from premature degeneration.

No MeSH data available.


Related in: MedlinePlus

Acer3 knockout induces premature degeneration of PCs.A and B. PC loss in Acer3 knockout mice at 8M of age. Immunostaining of cerebellar sagittal sections with antibody against calbindin D-28K, a PC marker (A). Red arrowheads indicate the regions where PCs were lost. Quantification of PCs (B). Images in A are the results from a representative mouse in each group. C. TUNEL assays for apoptosis in the cerebellum from Acer3+/+ and Acer3-/- mice. The cerebellar sections of Acer3+/+ and Acer3-/- mice at 8M of age were co-stained with the TUNEL assay reagent (green fluorescence) and anti-calbindin D28K antibody (red fluorescence). The images in A and C are the results from a representative mouse in each group. The data in B represent mean values ± SD, n = 4.
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pgen.1005591.g009: Acer3 knockout induces premature degeneration of PCs.A and B. PC loss in Acer3 knockout mice at 8M of age. Immunostaining of cerebellar sagittal sections with antibody against calbindin D-28K, a PC marker (A). Red arrowheads indicate the regions where PCs were lost. Quantification of PCs (B). Images in A are the results from a representative mouse in each group. C. TUNEL assays for apoptosis in the cerebellum from Acer3+/+ and Acer3-/- mice. The cerebellar sections of Acer3+/+ and Acer3-/- mice at 8M of age were co-stained with the TUNEL assay reagent (green fluorescence) and anti-calbindin D28K antibody (red fluorescence). The images in A and C are the results from a representative mouse in each group. The data in B represent mean values ± SD, n = 4.

Mentions: The impairment of motor coordination and balance capacity reflects a dysfunction of the cerebellum [44]. PCs are the exclusive output neurons in the cerebellar cortex [45] and are shown to be sensitive to age-related damage in the cerebellum [45,46]. These observations prompted us to test if Acer3 deficiency caused pathological effects on PCs in this brain region. We examined PCs in Acer3+/+ and Acer3-/- mice at 6 weeks or 8 months of age by immunohistochemical (IHC) staining with an antibody against calbindin D-28K, a PC marker. As shown in Fig 9A, calbindin D staining revealed well-arranged PCs between the molecular layer and granular layer of the cerebellum in both Acer3+/+ and Acer3-/- mice at 6 weeks of age with a similar cell number. At 8 months of age, while Acer3+/+ mice still maintained a similar number and pattern of PCs to 6-week-old mice, Acer3-/- mice exhibited a significant decrease in the number of PCs compared to their WT littermates and young animals (Fig 9A and 9B). Since Acer3 deficiency results in the accumulation of brain ceramides, which have been suggested to be pro-death bioactive lipids [47], we investigated if Acer3 deficiency induces apoptosis in PCs by performing terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assays. Interestingly, no apoptotic PCs were seen in the cerebellum of either 8-month-old Acer3-/- mice or their WT littermates (Fig 9C). These results suggest that Acer3 knockout induces premature degeneration of PCs through apoptosis that escapes from detection by TUNEL assays or through a mechanism other than apoptosis.


Alkaline Ceramidase 3 Deficiency Results in Purkinje Cell Degeneration and Cerebellar Ataxia Due to Dyshomeostasis of Sphingolipids in the Brain.

Wang K, Xu R, Schrandt J, Shah P, Gong YZ, Preston C, Wang L, Yi JK, Lin CL, Sun W, Spyropoulos DD, Rhee S, Li M, Zhou J, Ge S, Zhang G, Snider AJ, Hannun YA, Obeid LM, Mao C - PLoS Genet. (2015)

Acer3 knockout induces premature degeneration of PCs.A and B. PC loss in Acer3 knockout mice at 8M of age. Immunostaining of cerebellar sagittal sections with antibody against calbindin D-28K, a PC marker (A). Red arrowheads indicate the regions where PCs were lost. Quantification of PCs (B). Images in A are the results from a representative mouse in each group. C. TUNEL assays for apoptosis in the cerebellum from Acer3+/+ and Acer3-/- mice. The cerebellar sections of Acer3+/+ and Acer3-/- mice at 8M of age were co-stained with the TUNEL assay reagent (green fluorescence) and anti-calbindin D28K antibody (red fluorescence). The images in A and C are the results from a representative mouse in each group. The data in B represent mean values ± SD, n = 4.
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pgen.1005591.g009: Acer3 knockout induces premature degeneration of PCs.A and B. PC loss in Acer3 knockout mice at 8M of age. Immunostaining of cerebellar sagittal sections with antibody against calbindin D-28K, a PC marker (A). Red arrowheads indicate the regions where PCs were lost. Quantification of PCs (B). Images in A are the results from a representative mouse in each group. C. TUNEL assays for apoptosis in the cerebellum from Acer3+/+ and Acer3-/- mice. The cerebellar sections of Acer3+/+ and Acer3-/- mice at 8M of age were co-stained with the TUNEL assay reagent (green fluorescence) and anti-calbindin D28K antibody (red fluorescence). The images in A and C are the results from a representative mouse in each group. The data in B represent mean values ± SD, n = 4.
Mentions: The impairment of motor coordination and balance capacity reflects a dysfunction of the cerebellum [44]. PCs are the exclusive output neurons in the cerebellar cortex [45] and are shown to be sensitive to age-related damage in the cerebellum [45,46]. These observations prompted us to test if Acer3 deficiency caused pathological effects on PCs in this brain region. We examined PCs in Acer3+/+ and Acer3-/- mice at 6 weeks or 8 months of age by immunohistochemical (IHC) staining with an antibody against calbindin D-28K, a PC marker. As shown in Fig 9A, calbindin D staining revealed well-arranged PCs between the molecular layer and granular layer of the cerebellum in both Acer3+/+ and Acer3-/- mice at 6 weeks of age with a similar cell number. At 8 months of age, while Acer3+/+ mice still maintained a similar number and pattern of PCs to 6-week-old mice, Acer3-/- mice exhibited a significant decrease in the number of PCs compared to their WT littermates and young animals (Fig 9A and 9B). Since Acer3 deficiency results in the accumulation of brain ceramides, which have been suggested to be pro-death bioactive lipids [47], we investigated if Acer3 deficiency induces apoptosis in PCs by performing terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assays. Interestingly, no apoptotic PCs were seen in the cerebellum of either 8-month-old Acer3-/- mice or their WT littermates (Fig 9C). These results suggest that Acer3 knockout induces premature degeneration of PCs through apoptosis that escapes from detection by TUNEL assays or through a mechanism other than apoptosis.

Bottom Line: However, mechanisms that maintain the homeostasis of these bioactive sphingolipids in the brain remain unclear.Acer3 knockout causes an age-dependent accumulation of various ceramides and C18:1-monohexosylceramide and abolishes the age-related increase in the levels of sphingosine and S1P in the brain; thereby resulting in Purkinje cell degeneration in the cerebellum and deficits in motor coordination and balance.Our results indicate that Acer3 plays critically protective roles in controlling the homeostasis of various sphingolipids, including ceramides, sphingosine, S1P, and certain complex sphingolipids in the brain and protects Purkinje cells from premature degeneration.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, Stony Brook University, Stony Brook, New York, United States of America; Stony Brook Cancer Center, Stony Brook, New York, United States of America; Department of Hepatobiliary Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, China.

ABSTRACT
Dyshomeostasis of both ceramides and sphingosine-1-phosphate (S1P) in the brain has been implicated in aging-associated neurodegenerative disorders in humans. However, mechanisms that maintain the homeostasis of these bioactive sphingolipids in the brain remain unclear. Mouse alkaline ceramidase 3 (Acer3), which preferentially catalyzes the hydrolysis of C18:1-ceramide, a major unsaturated long-chain ceramide species in the brain, is upregulated with age in the mouse brain. Acer3 knockout causes an age-dependent accumulation of various ceramides and C18:1-monohexosylceramide and abolishes the age-related increase in the levels of sphingosine and S1P in the brain; thereby resulting in Purkinje cell degeneration in the cerebellum and deficits in motor coordination and balance. Our results indicate that Acer3 plays critically protective roles in controlling the homeostasis of various sphingolipids, including ceramides, sphingosine, S1P, and certain complex sphingolipids in the brain and protects Purkinje cells from premature degeneration.

No MeSH data available.


Related in: MedlinePlus