Mitochondrial Gene Therapy: Advances in Mitochondrial Gene Cloning, Plasmid Production, and Nanosystems Targeted to Mitochondria.

Mitochondrial gene therapy seems to be a valuable and promising strategy to treat mitochondrial disorders. The use of a therapeutic vector based on mitochondrial DNA, along with its affinity to the site of mitochondria, can be considered a powerful tool in the reestablishment of normal mitochondrial function. In line with this and for the first time, we successfully cloned the mitochondrial gene ND1 that was stably maintained in multicopy pCAG-GFP plasmid, which is used to transform E. coli. This mitochondrial-gene-based plasmid was encapsulated into nanoparticles. Furthermore, the functionalization of nanoparticles with polymers, such as cellulose or gelatin, enhances their overall properties and performance for gene therapy. The fluorescence arising from rhodamine nanoparticles in mitochondria and a fluorescence microscopy study show pCAG-GFP-ND1-based nanoparticles' cell internalization and mitochondria targeting. The quantification of GFP expression strongly supports this finding. This work highlights the viability of gene therapy based on mitochondrial DNA instigating further in vitro research and clinical translation.

Promoter Demethylation Upregulates STEAP1 Gene Expression in Human Prostate Cancer: In Vitro and In Silico Analysis.

The Six Transmembrane Epithelial Antigen of the Prostate (STEAP1) is an oncogene overexpressed in several human tumors, particularly in prostate cancer (PCa). However, the mechanisms involved in its overexpression remain unknown. It is well known that epigenetic modifications may result in abnormal gene expression patterns, contributing to tumor initiation and progression. Therefore, this study aimed to analyze the methylation pattern of the STEAP1 gene in PCa versus non-neoplastic cells. Bisulfite amplicon sequencing of the CpG island at the STEAP1 gene promoter showed a higher methylation level in non-neoplastic PNT1A prostate cells than in human PCa samples. Bioinformatic analysis of the GEO datasets also showed the STEAP1 gene promoter as being demethylated in human PCa, and a negative association with STEAP1 mRNA expression was observed. These results are supported by the treatment of non-neoplastic PNT1A cells with DNMT and HDAC inhibitors, which induced a significant increase in STEAP1 mRNA expression. In addition, the involvement of HDAC in the regulation of STEAP1 mRNA expression was corroborated by a negative association between STEAP1 mRNA expression and HDAC4,5,7 and 9 in human PCa. In conclusion, our work indicates that STEAP1 overexpression in PCa can be driven by the hypomethylation of STEAP1 gene promoter.

Neonatal presentation of growth hormone deficiency in CHARGE syndrome: the benefit of early treatment on long-term growth.

CHARGE syndrome is a complex disorder involving multiple congenital anomalies and is caused by heterozygous mutations in the CHD7 gene. Growth retardation is a characteristic finding and about 10% of cases present growth hormone (GH) deficiency. GH treatment of short stature in CHARGE syndrome has shown some benefit, but normal height is rarely attained. We report a girl with CHARGE syndrome due to a de novo frameshift mutation in the CHD7 gene (c.2509_2512delCATT), in whom recurrent hypoglycaemia led to the diagnosis of GH deficiency in the second month of life. Early initiation of treatment with recombinant GH resulted in normal growth over ten years of follow-up. This case is the youngest reported CHARGE patient to be diagnosed and treated for GH deficiency and demonstrates that GH deficiency in CHARGE syndrome may manifest early in life through hypoglycaemia, before growth retardation is noted, and can be successfully treated with recombinant GH.

Maturity-Onset Diabetes of the Young (MODY) in Portugal: Novel GCK, HNFA1 and HNFA4 Mutations.

Maturity-onset diabetes of the young (MODY) is a frequently misdiagnosed type of diabetes, which is characterized by early onset, autosomal dominant inheritance, and absence of insulin dependence. The most frequent subtypes are due to mutations of the GCK (MODY 2), HNF1A (MODY 3), and HNF4A (MODY 1) genes. We undertook the first multicenter genetic study of MODY in the Portuguese population. The GCK, HNF1A, and HNF4A genes were sequenced in 46 unrelated patients that had at least two of the three classical clinical criteria for MODY (age at diagnosis, family history, and clinical presentation). The functional consequences of the mutations were predicted by bioinformatics analysis. Mutations were identified in 23 (50%) families. Twelve families had mutations in the GCK gene, eight in the HNF1A gene, and three in the HNF4A gene. These included seven novel mutations (GCK c.494T>C, GCK c.563C>G, HNF1A c.1623G>A, HNF1A c.1729C>G, HNF4A c.68delG, HNF4A c.422G>C, HNF4A c.602A>C). Mutation-positive patients were younger at the time of diagnosis when compared to mutation-negative patients (14.3 vs. 23.0 years, p = 0.011). This study further expands the spectrum of known mutations associated with MODY, and may contribute to a better understanding of this type of diabetes and a more personalized clinical management of affected individuals.

Combined Pituitary Hormone Deficiency Caused by a Synonymous HESX1 Gene Mutation.

CONTEXT: Mutations in the HESX1 gene can give rise to complex phenotypes that involve variable pituitary hormone deficiencies and other developmental defects. CASE DESCRIPTION: A 14-year-old boy presented with short stature and delayed puberty and received a diagnosis of GH deficiency, central hypothyroidism, hypogonadotropic hypogonadism, and secondary adrenal insufficiency. He had anterior pituitary hypoplasia, ectopic posterior pituitary, and an interrupted pituitary stalk. Genetic studies uncovered a heterozygous variant in exon 2 of the HESX1 gene (c.219C>T; p.Ser73Ser). This single base change was predicted to be synonymous at the translational level but was shown to cause skipping of exon 2 in the RNA transcript. CONCLUSIONS: This study of a patient with combined pituitary hormone deficiency revealed an unusual synonymous mutation of the HESX1 gene leading to abnormal RNA processing and indicates the importance of investigating silent variants that at first glance appear to be benign.

Lack of association of vitamin D receptor gene polymorphisms with susceptibility to type 1 diabetes mellitus in the Portuguese population.

The vitamin D receptor (VDR) gene is a candidate gene for susceptibility to autoimmune disorders. Association studies of VDR polymorphisms and risk of type 1 diabetes often produced conflicting results in different ethnic backgrounds. The aim of this study was to test for association between common VDR polymorphisms and the genetic susceptibility to type 1 diabetes in the Portuguese population. We genotyped 207 patients with type 1 diabetes and 249 controls for the FokI T>C (rs10735810), BsmI A>G (rs1544410), ApaI G>T (rs7975232), and TaqI C>T (rs731236) single nucleotide polymorphisms by polymerase chain reaction and restriction fragment length polymorphism analysis. The distribution of VDR genotype, allele, and haplotype frequencies did not differ significantly between patients and controls. These data suggest that the single nucleotide polymorphisms of the VDR gene are unlikely to contribute significantly to type 1 diabetes susceptibility in the Portuguese population.

Neonatal presentation of growth hormone deficiency in CHARGE syndrome: the benefit of early treatment on long-term growth

SUMMARY CHARGE syndrome is a complex disorder involving multiple congenital anomalies and is caused by heterozygous mutations in the CHD7 gene. Growth retardation is a characteristic finding and about 10% of cases present growth hormone (GH) deficiency. GH treatment of short stature in CHARGE syndrome has shown some benefit, but normal height is rarely attained. We report a girl with CHARGE syndrome due to a de novo frameshift mutation in the CHD7 gene (c.2509_2512delCATT), in whom recurrent hypoglycaemia led to the diagnosis of GH deficiency in the second month of life. Early initiation of treatment with recombinant GH resulted in normal growth over ten years of follow-up. This case is the youngest reported CHARGE patient to be diagnosed and treated for GH deficiency and demonstrates that GH deficiency in CHARGE syndrome may manifest early in life through hypoglycaemia, before growth retardation is noted, and can be successfully treated with recombinant GH.

Genetic polymorphism of CYP2D6 influences susceptibility to papillary thyroid cancer.

OBJECTIVE: Xenobiotic-metabolizing enzymes are widely polymorphic and confer interindividual variation in the ability to detoxify carcinogens or to activate pro-carcinogens. A common polymorphism of cytochrome P450 2D6 (CYP2D6) results in lack of enzyme activity and has been associated with an altered susceptibility to several cancers. The aim of this study was to investigate the association between the CYP2D6 poor metaboliser genotype and the risk of papillary thyroid cancer (PTC). DESIGN: Retrospective case-control study. PATIENTS: One hundred and eighty-seven patients with PTC and 256 controls. MEASUREMENTS: Genotyping was performed by PCR and restriction enzyme analysis to detect the presence of the common CYP2D6*4 poor metaboliser allele. RESULTS: The frequency of individuals with the homozygous poor metaboliser genotype was lower in the patient group [1.6 vs. 5.5%, P = 0.037, OR = 0.28 (95% CI 0.09-0.93)]. The CYP2D6*4 allele frequency was also lower in the patient group [13.4 vs. 21.7%, P = 0.002, OR = 0.56 (95% CI 0.39-0.80)]. CONCLUSIONS: The results suggest that the poor metaboliser genotype is associated with a protective effect against PTC. This could be explained by a possible role of CYP2D6 on the metabolic activation of putative environmental chemical thyroid carcinogens or by linkage to another cancer-causing gene. Further research may allow the identification of metabolic risk factors and contribute towards understanding the molecular mechanisms involved in thyroid carcinogenesis.

O jato de ar quente como estímulo punidor em rattus norvegicus / The hot air blast as punisher stimulus in rattus norvegicus

Na pesquisa experimental sobre controle aversivo, o choque elétrico tem sido predominantemente utilizado como estímulo punidor. O presente trabalho descreve o uso de um equipamento que emite um jato de ar quente o qual pode ser um estímulo alternativo a ser usado em estudos sobre contingências aversivas. A função punidora do jato de ar quente foi avaliada tanto quando aplicado continuamente (CRF) quanto intermitentemente (FR3) e nos dois casos foi registrada supressão parcial (98,4 por cento e 71,15 por cento, respectivamente) da resposta de pressão à barra previamente fortalecida de forma contínua. A supressão foi maior na punição contínua, corroborando os dados com choque elétrico descritos na literatura. O equipamento e o estímulo mostraram-se adequados do ponto de vista técnico e científico e o aparato pode ser uma alternativa atraente do ponto de vista econômico.

In experimental research on aversive control, electric shock has been predominantly used as a punisher stimulus. The present work describes the use of an apparatus that produces a hot air blast which can be an alternative stimulus to be used in research on aversive contingencies. The punishing function of the hot air blast was evaluated in both continuous (CRF) and intermittent (FR3) schedules and, in both cases, a partial suppression (98,4 percent and 71,15 percent, respectively) of the lever press responding was found, after a history of the continuous reinforcement. Suppression was bigger when the punishing stimulus was applied continuously and these data corroborate the data obtained with electric shock, described in the literature. Both the apparatus and the stimulus seemed to be appropriate from a technical and scientific perspective and the apparatus may become an attractive alternative from a financial standpoint.