Ethylenedioxy-PIP2 Oxalate Reduces Ganglioside Storage in Juvenile Sandhoff Disease Mice

Abstract

Sandhoff disease is an incurable neurodegenerative disorder caused by mutations in the lysosomal hydrolase β-hexosaminidase. Deficiency in this enzyme leads to excessive accumulation of ganglioside GM2 and its asialo derivative, GA2, in brain and visceral tissues. Small molecule inhibitors of ceramide-specific glucosyltransferase, the first committed step in ganglioside biosynthesis, reduce storage of GM2 and GA2. Limited brain access or adverse effects have hampered the therapeutic efficacy of the clinically approved substrate reduction molecules, eliglustat tartrate and the imino sugar NB-DNJ (Miglustat). The novel eliglustat tartrate analog, 2-(2,3-dihydro-1H-inden-2-yl)-N-((1R,2R)-1-(2,3-dihydrobenzo[b][1, 4]dioxin-6-yl)-1-hydroxy-3-(pyrrolidin-1-yl)propan-2-yl)acetamide (EtDO-PIP2, CCG-203586 or "3h"), was recently reported to reduce glucosylceramide in murine brain. Here we assessed the therapeutic efficacy of 3h in juvenile Sandhoff (Hexb-/-) mice. Sandhoff mice received intraperitoneal injections of phosphate buffered saline (PBS) or 3h (60 mg/kg/day) from postnatal day 9 (p-9) to postnatal day 15 (p-15). Brain weight and brain water content was similar in 3h and PBS-treated mice. 3h significantly reduced total ganglioside sialic acid, GM2, and GA2 content in cerebrum, cerebellum and liver of Sandhoff mice. Data from the liver showed that 3h reduced the key upstream ganglioside precursor (glucosylceramide), providing evidence for an on target mechanism of action. No significant differences were seen in the distribution of cholesterol or of neutral and acidic phospholipids. These data suggest that 3h can be an effective alternative to existing substrate reduction molecules for ganglioside storage diseases.

The development and use of small molecule inhibitors of glycosphingolipid metabolism for lysosomal storage diseases

“…A signifi cant reduction in ganglioside GM2 and GA2 was observed in the cerebrums and cerebellums of the mice, a response not observed with eliglustat ( 54 ). These data support the view that PDMP-based homologs can be designed to lower GSLs within the CNS.…”

Bis(monoacylglycero)phosphate: a secondary storage lipid in the gangliosidoses

“…To address this possibility, we analyzed BMP levels in young Hex ␤ ( Ϫ / Ϫ ) mice at p15, well before the onset of behavioral symptoms and infl ammation. However, GM2 ganglioside storage is observable in the p15 Hex ␤ ( Ϫ / Ϫ ) mice ( 58 ). We found that brain levels of BMP were higher in the p15 Hex ␤ ( Ϫ / Ϫ ) mice than in the normal age-matched controls.…”

“…In our BMP storage was observed in the livers of SD mice ( Table 1 ), where N-glycolylneuraminic acid-GM2 is also stored ( 58 ). This observation indicates that BMP co-accumulates with ganglioside storage, rather than as a downstream by-product of a nonfunctional enzyme.…”

“…GM1 is not stored in the livers of ␤ -gal ( Ϫ / Ϫ ) mice, as GM1 synthesis does not occur in mouse liver ( 58 ). On the other hand, Rockwell, and Sam Eaton for assistance with lipid analysis and Joseph Alroy for gifting bear brain tissues.…”

Development of targeted therapies for Parkinson's disease and related synucleinopathies

“…Although anecdotal reports in individual patients suggest an impact on neurological manifestations in type 3 GD, a controlled clinical trial involving 25 subjects over a two year time course failed to demonstrate effectiveness on neurological endpoints such as saccadic eye movements ( 28 ). However, newer small molecule modulators with the potential to gain access to the CNS and impact glycolipid metabolism are now emerging (29)(30)(31)(32).…”