Additive reductions in zebrafish PRPS1 activity result in a spectrum of deficiencies modeling several human PRPS1-associated diseases

Abstract

Phosphoribosyl pyrophosphate synthetase-1 (PRPS1) is a key enzyme in nucleotide biosynthesis, and mutations in PRPS1 are found in several human diseases including nonsyndromic sensorineural deafness, Charcot-Marie-Tooth disease-5, and Arts Syndrome. We utilized zebrafish as a model to confirm that mutations in PRPS1 result in phenotypic deficiencies in zebrafish similar to those in the associated human diseases. We found two paralogs in zebrafish, prps1a and prps1b and characterized each paralogous mutant individually as well as the double mutant fish. Zebrafish prps1a mutants and prps1a;prps1b double mutants showed similar morphological phenotypes with increasingly severe phenotypes as the number of mutant alleles increased. Phenotypes included smaller eyes and reduced hair cell numbers, consistent with the optic atrophy and hearing impairment observed in human patients. The double mutant also showed abnormal development of primary motor neurons, hair cell innervation, and reduced leukocytes, consistent with the neuropathy and recurrent infection of the human patients possessing the most severe reductions of PRPS1 activity. Further analyses indicated the phenotypes were associated with a prolonged cell cycle likely resulting from reduced nucleotide synthesis and energy production in the mutant embryos. We further demonstrated the phenotypes were caused by delays in the tissues most highly expressing the prps1 genes.

Zebrafish Model for Nonsyndromic X‐Linked Sensorineural Deafness, DFNX1

“…With these stable mutants, a deeper understanding of the mechanisms underlying this reduction of hair cell count could be established. Pei et al (2016) reported a reduced number of hair cells in lateral line neuromasts in prps1a mutants, which is consistent with our findings of reduced inner ear hair cells in the present study. However, they did not find such phenotype in prps1b mutants.…”

A subset of SMN complex members have a specific role in tissue regeneration via ERBB pathway-mediated proliferation

“…Hair cell staining and quantification were as described (53). Briefly, for analyzing hair cell development, embryos from heterozygotic incrosses were cultured until 5 dpf, and then placed in a cell strainer (BD Falcon) for staining with 2 µM YoPro-1 for 30 minutes.…”

Patient-derivedphosphoribosyl pyrophosphate synthetasemutations inDrosophilaresult in autophagy and lysosome dysfunction

“…Interestingly, while PRPS2 is non-essential for development, PRPS2 knockout mice are resistant to Eµ-Myc-driven cancer development, suggesting that PRPS2 is specifically required for tumorigenesis (Cunningham et al 2014). A zebrafish model of PRPS deficiency has also been recently generated (Pei et al 2016). The prps1a and prps1b double mutant animals fail to properly develop but show some phenotypic similarity to human PRPS1-associated diseases.…”