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TY - JOUR

T1 - High-Throughput Screen Fails to Identify Compounds That Enhance Residual Enzyme Activity of Mutant N-Acetyl-α-Glucosaminidase in Mucopolysaccharidosis Type IIIB

AU - Meijer, O. L. M.

AU - van den Biggelaar, P.

AU - Ofman, R.

AU - Wijburg, F. A.

AU - van Vlies, N.

PY - 2017

Y1 - 2017

N2 - In the severe neurodegenerative disorder mucopolysaccharidosis type IIIB (MPSIIIB or Sanfilippo disease type B), deficiency of the lysosomal enzyme N-acetyl-α-glucosaminidase (NAGLU) results in accumulation of heparan sulfate. Patients present with a severe, rapidly progressing phenotype (RP) or a more attenuated, slowly progressing phenotype (SP). In a previous study, residual NAGLU activity in fibroblasts of SP patients could be increased by culturing at 30°C, probably as a result of improved protein folding and lysosomal targeting under these conditions. Chaperones are molecules which influence protein folding and could therefore have therapeutic potential in SP MPSIIIB patients. Here we studied the effects of 1,302 different compounds on residual NAGLU activity in SP MPSIIIB patient fibroblasts including 1,280 approved compounds from the Prestwick Chemical Library. Skin fibroblasts of healthy controls, an SP MPSIIIB patient (homozygous for the temperature sensitive mutation p.S612G) and an RP MPSIIIB patient (homozygous for the p.R297* mutation and non-temperature sensitive), were used. A high-throughput assay for measurement of NAGLU activity was developed and validated, after which 1,302 different molecules were tested for their potential to increase NAGLU activity. None of the compounds tested were able to enhance NAGLU activity. This high-throughput screen failed to identify compounds that could enhance residual activity of mutant NAGLU in fibroblasts of SP MPSIIIB patients with temperature sensitive mutations. To therapeutically simulate the positive effect of lower temperatures on residual NAGLU activity, first more insight is needed into the mechanisms underlying this temperature dependent increase

AB - In the severe neurodegenerative disorder mucopolysaccharidosis type IIIB (MPSIIIB or Sanfilippo disease type B), deficiency of the lysosomal enzyme N-acetyl-α-glucosaminidase (NAGLU) results in accumulation of heparan sulfate. Patients present with a severe, rapidly progressing phenotype (RP) or a more attenuated, slowly progressing phenotype (SP). In a previous study, residual NAGLU activity in fibroblasts of SP patients could be increased by culturing at 30°C, probably as a result of improved protein folding and lysosomal targeting under these conditions. Chaperones are molecules which influence protein folding and could therefore have therapeutic potential in SP MPSIIIB patients. Here we studied the effects of 1,302 different compounds on residual NAGLU activity in SP MPSIIIB patient fibroblasts including 1,280 approved compounds from the Prestwick Chemical Library. Skin fibroblasts of healthy controls, an SP MPSIIIB patient (homozygous for the temperature sensitive mutation p.S612G) and an RP MPSIIIB patient (homozygous for the p.R297* mutation and non-temperature sensitive), were used. A high-throughput assay for measurement of NAGLU activity was developed and validated, after which 1,302 different molecules were tested for their potential to increase NAGLU activity. None of the compounds tested were able to enhance NAGLU activity. This high-throughput screen failed to identify compounds that could enhance residual activity of mutant NAGLU in fibroblasts of SP MPSIIIB patients with temperature sensitive mutations. To therapeutically simulate the positive effect of lower temperatures on residual NAGLU activity, first more insight is needed into the mechanisms underlying this temperature dependent increase

U2 - 10.1007/8904_2017_51

DO - 10.1007/8904_2017_51

M3 - Article

C2 - 28836185

VL - 39

SP - 97

EP - 106

JO - JIMD reports

JF - JIMD reports

SN - 2192-8304

ER -