The designer aminoglycoside NB84 significantly reduces glycosaminoglycan accumulation associated with MPS I-H in the Idua-W392X mouse

Abstract

Suppression therapy utilizes compounds that suppress translation termination at in-frame premature termination codons (PTCs) to restore full-length, functional protein. This approach may provide a treatment for diseases caused by nonsense mutations such as mucopolysaccharidosis type I-Hurler (MPS I-H). MPS I-H is a lysosomal storage disease caused by severe α-L-iduronidase deficiency and subsequent lysosomal glycosaminoglycan (GAG) accumulation. MPS I-H represents a good target for suppression therapy because the majority of MPS I-H patients carry nonsense mutations, and restoration of even a small amount of functional α-L-iduronidase may attenuate the MPS I-H phenotype. In this study, we investigated the efficiency of suppression therapy agents to suppress the Idua-W392X nonsense mutation in an MPS I-H mouse model. The drugs tested included the conventional aminoglycosides gentamicin, G418, amikacin, and paromomycin. In addition, the designer aminoglycosides NB54 and NB84, two compounds previously designed to mediate efficient PTC suppression with reduced toxicity, were also examined. Overall, NB84 suppressed the Idua-W392X nonsense mutation much more efficiently than any of the other compounds tested. NB84 treatment restored enough functional α-L-iduronidase activity to partially reverse abnormal GAG accumulation and lysosomal abundance in mouse embryonic fibroblasts derived from the Idua-W392X mouse. Finally, in vivo administration of NB84 to Idua-W392X mice significantly reduced urine GAG excretion and tissue GAG storage. Together, these results suggest that NB84-mediated suppression therapy has the potential to attenuate the MPS I-H disease phenotype.

Effect of Readthrough Treatment in Fibroblasts of Patients Affected by Lysosomal Diseases Caused by Premature Termination Codons

“…Hurler disease) no biochemical improvement was observed after gentamicin administration [19]. Accordingly, we observed a similar effect in cultured fibroblasts derived from 3 patients carrying the analogous human mutation (mutation p.Trp402* of IDUA; Hurler disease), as no increase in enzymatic activity was detected.…”

“…In the last few years, other potential strategies such as pharmacological chaperones [8], or the suppression of pathogenic nonsense mutations through the induction of translational readthrough have emerged [2,[9][10][11][12][13][14][15][16][17][18]. To this effect, aminoglycoside antibiotics such as gentamicin [16,17], and small molecules such as PTC124 [18] and NB84 [19], have been described to induce PTC readthrough, eluding the NMD mechanism and allowing the formation of stable mRNAs encoding for full-length mutant, but probably still quite active, proteins [20,21]. These products reduce proofreading of codon-anticodon recognition in the ribosome, allowing the suppression of PTCs and, as a general rule, the insertion of glutamine or tryptophan at premature UAG/UAA or UGA codons, respectively, occurs [17].…”

Synthetic Aminoglycosides Efficiently Suppress Cystic Fibrosis Transmembrane Conductance Regulator Nonsense Mutations and Are Enhanced by Ivacaftor

“…Other approaches to augment rescue of CFTR nonsense mutations, such as the coadministration of polyanions, such as poly-L-aspartic acid, or NMD inhibitors, such as NMDI-1, are other options that could be tested in the future (13,55). Furthermore, time-dependent increases in activity have been observed with prolonged administration of NB84 in a mouse model of Hurler's syndrome (38), a finding also observed in patients with CF administered ataluren in an open label trial (16), suggesting that enhanced readthrough with these agents may be possible with chronic administration in vivo.…”

Designer Aminoglycosides That Selectively Inhibit Cytoplasmic Rather than Mitochondrial Ribosomes Show Decreased Ototoxicity

“…In this context, we have recently demonstrated the ability of some of our recent lead compounds of the NB series, including NB74 and NB84, to partially restore protein function in various clinically relevant cellular and animal models of genetic diseases, including cystic fibrosis (46), Rett syndrome (47,48), Usher syndrome (49 -51), and Hurler syndrome (52,53). These observations, together with the relatively low toxicity of NB74 and NB84, encourage the further testing of these novel designer AGs in animal models and human subjects to maximize the translational impact of our work.…”