Three novel variants (p.Glu178Lys, p.Val245Met, p.Ser250Phe) of the phenylalanine hydroxylase (PAH) gene impair protein expression and function in vitro

The c.503A>G polymorphism in ZIP1-II of Pacific oyster Crassostrea gigas associated with zinc content

The Pacific oyster Crassostrea gigas is renowned for its high zinc content, but the significant variation among individuals diminishes its value as a reliable source of zinc supplementation. The Zrt/Irt-like protein 1 (ZIP1), a pivotal zinc transporter that facilitates zinc uptake in various organisms, plays crucial roles in regulating zinc content. In the present study, polymorphisms of a ZIP1 gene in C. gigas (CgZIP1-II) were investigated, and their association with zinc content was evaluated through preliminary association analysis in 41 oysters and verification analysis in another 200 oysters. A total of 17 single nucleotide polymorphisms (SNPs) were identified in the exonic region of CgZIP1-II gene, with c.503A>G significantly associated with zinc content. Protein sequence and structure prediction showed that c.503A>G caused a p.Met110Val nonsynonymous mutation located in the metal-binding region of CgZIP1-II, which could influence its affinity for zinc ions, thereby modulating its zinc transport functionality. These results indicate the potential influence of CgZIP1-II polymorphisms on zinc content and provide candidate markers for selecting C. gigas with high zinc content.

[In vitro expression and functional analyses of the mutants p.R243Q, p.R241C and p.Y356X of the human phenylalanine hydroxylase]

OBJECTIVES

To study the in vitro expression of three phenylalanine hydroxylase (PAH) mutants (p.R243Q, p.R241C, and p.Y356X) and determine their pathogenicity.

METHODS

Bioinformatics techniques were used to predict the impact of PAH mutants on the structure and function of PAH protein. Corresponding mutant plasmids of PAH were constructed and expressed in HEK293T cells. Quantitative reverse transcription polymerase chain reaction was used to measure the mRNA expression levels of the three PAH mutants, and their protein levels were assessed using Western blot and enzyme-linked immunosorbent assay.

RESULTS

Bioinformatics analysis predicted that all three mutants were pathogenic. The mRNA expression levels of the p.R243Q and p.R241C mutants in HEK293T cells were similar to the mRNA expression level of the wild-type control (P>0.05), while the mRNA expression level of the p.Y356X mutant significantly decreased (P<0.05). The PAH protein expression levels of all three mutants were significantly reduced compared to the wild-type control (P<0.05). The extracellular concentration of PAH protein was reduced in the p.R241C and p.Y356X mutants compared to the wild-type control (P<0.05), while there was no significant difference between the p.R243Q mutant and the wild type control (P>0.05).

CONCLUSIONS

p.R243Q, p.R241C and p.Y356X mutants lead to reduced expression levels of PAH protein in eukaryotic cells, with p.R241C and p.Y356X mutants also affecting the function of PAH protein. These three PAH mutants are to be pathogenic.