Fig. 5: FAN1 slows the rate of HTT CAG repeat expansions in a nuclease-dependent manner in an iPSC model of HD. | Nature Neuroscience

Fig. 5: FAN1 slows the rate of HTT CAG repeat expansions in a nuclease-dependent manner in an iPSC model of HD.

From: Exome sequencing of individuals with Huntington’s disease implicates FAN1 nuclease activity in slowing CAG expansion and disease onset

Fig. 5

a, Immunoblot of FAN1 in Q109 HD iPSC lines. Parent Q109 lines with wild-type FAN1 (Q109-n5 (lane 1) and Q109-n1 (lane 5)); Q109 lines with D960A variant (heterozygous (lane 2) and homozygous (lane 3)); and Q109 FAN1 knockout lines (Q109-n5 (lane 4) and Q109-n1 (lane 6)). Blots were repeated twice to confirm results. b, Representative electropherograms of fluorescent PCR and capillary electrophoresis of the HTT CAG repeat in 109-FAN1+/+, 109-FAN1−/−, 109-FAN1+/D960A and 109-FAN1D960A/D960A iPSCs at baseline and after time in culture. The red dotted line indicates baseline HTT CAG repeat length. c, 109-FAN1−/− iPSCs (n = 6 clones) exhibit significantly faster HTT CAG repeat expansion rates than 109-FAN1+/+ iPSCs (n = 7 clones) (0.0661 CAG per day) (P = 1.5 × 10−5). Genome editing performed in Q109-n1 iPSCs. d, Change in modal HTT CAG repeat in post-mitotic neurons generated from 109-FAN1+/+ iPSCs (n = 5) and 109-FAN1−/− iPSCs (n = 4 clones). 109-FAN1−/− neurons demonstrate significantly faster rates of HTT CAG repeat expansion than 109-FAN1+/+ neurons (P = 1.1 × 10−2). e, FAN1D960A HD-iPSCs show dose-dependent increase in HTT CAG repeat expansion over time in culture (n = 3 clones per genotype, each cultured in triplicate wells). Genome editing performed in Q109-n5 iPSCs. f, D960A mutations enhance HTT CAG repeat expansions in a dose-dependent manner in NPCs derived from 109-FAN1+/+, 109-FAN1+/D960A and 109-FAN1D960A/D960A iPSCs (n = 1 clone per genotype, cultured in triplicate wells). Values are expressed as mean ± s.e.m.

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