Tyrosine hydroxylase variants influence protein expression, cellular localization, stability, enzymatic activity and the physical interaction between tyrosine hydroxylase and GTP cyclohydrolase 1.

Tyrosine hydroxylase (TH) is the rate-limiting enzyme in dopamine biosynthesis catalyzing the tetrahydrobiopterin (BH4 )-dependent hydroxylation of tyrosine to L-DOPA. Here, we analyzed 25 TH variants associated with various degrees of dopa-responsive dystonia and evaluate the effect of each variant on protein stability, activity and cellular localization. Furthermore, we investigated the physical interaction between TH and human wildtype (wt) GTP cyclohydrolase 1 (GTPCH) and the effect of variants on this interaction. Our in vitro results classify variants according to their resistance to proteinase K digestion into three groups (stable, intermediate, unstable). Based on their cellular localization, two groups of variants can be identified, variant group one with cytoplasmic distribution and variant group two forming aggregates. These aggregates do not correlate with loss of enzymatic activity but nevertheless might be a good target for molecular chaperones. Unfortunately, no obvious correlation between the half-life of a variant and its enzymatic activity or between solubility, stability and enzymatic activity of a given variant could be found. Excitingly, some variants disrupt the physical interaction between TH and human wildtype GTPCH, thereby interfering with enzymatic activity and offering new druggable targets for therapy. Taken together, our results highlight the importance of an in-depth molecular analysis of each variant in order to be able to classify groups of disease variants and to find specific therapies for each subgroup. Stand-alone in silico analyses predict less precise the effect of specific variants and should be combined with other in vitro analyses in cellular model systems.

Phenotypic prediction in glutaric aciduria type 1 combining in silico and in vitro modeling with real-world data.

Glutaric aciduria type 1 (GA1) is caused by inherited deficiency of glutaryl-CoA dehydrogenase (GCDH). To further understand the unclear genotype-phenotype correlation, we transfected mutated GCDH into COS-7 cells resembling known biallelic GCDH variants of 47 individuals with GA1. In total, we modeled 36 genotypes with 32 missense variants. Spectrophotometry demonstrated an inverse correlation between residual enzyme activity and the urinary concentration of glutaric acid and 3-hydroxyglutaric acid, confirming previous studies (Pearson correlation, r = -0.34 and r = -0.49, p = 0.045 and p = 0.002, respectively). In silico modeling predicted high pathogenicity for all genotypes, which caused a low enzyme activity. Western blotting revealed a 2.6-times higher GCDH protein amount in patients with an acute encephalopathic crisis (t-test, p = 0.015), and high protein expression correlated with high in silico protein stability (Pearson correlation, r = -0.42, p = 0.011). The protein amount was not correlated with the enzyme activity (Pearson correlation, r = 0.09, p = 0.59). To further assess protein stability, proteolysis was performed, showing that the p.Arg88Cys variant stabilized a heterozygous less stable variant. We conclude that an integration of different data sources helps to predict the complex clinical phenotype in individuals with GA1.

Fabrication and Characterization of a Microscale Piezoelectric Vibrator Based on Electrohydrodynamic Jet Printed PZT Thick Film.

This paper proposes a novel way of preparing a PZT thick film micro vibrator using the electrohydrodynamic jet (E-Jet) printing technique. Initially, a micro piezoelectric vibrator was simulated and designed for obtaining optimized structure, which has a total thickness of less than 600 µm. Subsequently, the PZT thick film element was directly printed on the elastic body using the E-Jet printing. This method avoids the glue fabrication process involved in the bulk piezoelectric fabrication, thus avoiding the limits of voltage drops, isolating and absorbing amplitude usually occurred in the vibrator having glue interface. It was observed that B02 and B03 modes were generated at frequencies of 29.74 and 79.14 kHz, respectively, and the amplitudes of B02 and B03 modes were 406 and 176 nm, respectively. The error between the simulation and test result in the B03 modal is only 0.35%, which indicates the accuracy of the simulation analysis and the fabrication process. The PZT thick film traveling-wave micro vibrator successfully realized bidirectional rotation of a rotor, with a maximum speed of 681 rpm, which also shows a linear relationship between excitation voltage and rotary speed. This paper provides an effective method for preparing a micro piezoelectric vibrator for MEMS ultrasonic devices, which simplifies the manufacturing process and enhances the performance of the piezoelectric vibrator.

Clinical and genetic characteristics of 17 Chinese patients with glycogen storage disease type IXa.

Glycogen storage disease (GSD) type IXa is caused by PHKA2 mutation, which accounts for about 75% of all the GSD type IX cases. Here we first summarized the clinical data and analyzed the PHKA2 gene of 17 Chinese male patients suspected of having GSD type IXa. Clinical symptoms of our patients included hepatomegaly, growth retardation, and liver dysfunction. The clinical and biochemical manifestations improved and even disappeared with age. We detected 14 mutations in 17 patients, including 8 novel mutations; exons 2 and 4 were hot spots in this research. In conclusion, glycogen storage disease type IXa is a mild disorder with a favorable prognosis, and there was no relationship between genotype and phenotype of this disease.

[SMARCAL1 gene analysis of 2 Chinese Schimke immuno-osseous dysplasia children].

OBJECTIVE: Schimke immuno-osseous dysplasia (SIOD), is an autosomal recessive inherited disease caused by SMARCAL1 (MIM:20606622) mutations, while in about half of the patients no any mutation in SMARCAL1 could be found. This disease involves multiple systems and is characterized by short and dissymmetric stature with spondyloepiphyseal dysplasia, progressive renal failure, lymphopenia with recurrent infections, and hyperpigmented macules. This study aimed to analyze SMARCAL1 gene of 2 unrelated suspected SIOD children, to make definite diagnosis, and find more SMARCAL1 mutation types of Chinese SIOD. METHOD: Two suspected Chinese Han male SIOD children who visited our hospital from 2008 to 2014, aged 3 y 6 m and 7 y 8 m, both were short and had spondyloepiphyseal dysplasia, progressive renal failure, lymphopenia with recurrent infections. After informed consent, they and their parents's DNA were extracted from blood. PCRs for all 16 exons of SMARCAL1 were performed and PCR products were purified by 2% gel electrophoresis and sequenced directly. Pathogenicity of missense variations was confirmed by SIFT and sequencing SMARCAL1 of fifty normal controls. RESULT: (1) Four gene variations were found in the two children: Two reported missense mutations c.1129G>C, p.Glu377Gln and c.1933C>T, p. Arg645Cys. Two splicing mutations c.1334+1G>A and c.2142-1 G>A were detected. (2) c.1129G>C, p.Glu377Gln were reported as a disease-causing mutations before, but it was an single nucleotide polymorphism (SNP) which was found in 15 of 50 normal controls. (3) Two novel splicing mutations were found in this study: c.1334+1G>A and c.2142-1 G>A. CONCLUSION: (1) We detected 3 disease-causing mutations in 2 SIOD children by SMARCAL1 gene analysis, while 2 splicing mutations were novel mutations. (2) c.1129G>C, p.Glu377Gln was a SNP but not a disease-causing mutation at least in Chinese population.