Disorders of synaptic vesicle fusion machinery.

The revolution in genetic technology has ushered in a new age for our understanding of the underlying causes of neurodevelopmental, neuromuscular and neurodegenerative disorders, revealing that the presynaptic machinery governing synaptic vesicle fusion is compromised in many of these neurological disorders. This builds upon decades of research showing that disturbance to neurotransmitter release via toxins can cause acute neurological dysfunction. In this review, we focus on disorders of synaptic vesicle fusion caused either by toxic insult to the presynapse or alterations to genes encoding the key proteins that control and regulate fusion: the SNARE proteins (synaptobrevin, syntaxin-1 and SNAP-25), Munc18, Munc13, synaptotagmin, complexin, CSPα, α-synuclein, PRRT2 and tomosyn. We discuss the roles of these proteins and the cellular and molecular mechanisms underpinning neurological deficits in these disorders.

Severe Impairment of TNF Post-transcriptional Regulation Leads to Embryonic Death.

Post-transcriptional regulation mechanisms control mRNA stability or translational efficiency via ribosomes, and recent evidence indicates that it is a major determinant of the accurate levels of cytokine mRNAs. Transcriptional regulation of Tnf has been well studied and found to be important for the rapid induction of Tnf mRNA and regulation of the acute phase of inflammation, whereas study of its post-transcriptional regulation has been largely limited to the role of the AU-rich element (ARE), and to a lesser extent, to that of the constitutive decay element (CDE). We have identified another regulatory element (NRE) in the 3' UTR of Tnf and demonstrate that ARE, CDE, and NRE cooperate in vivo to efficiently downregulate Tnf expression and prevent autoimmune inflammatory diseases. We also show that excessive TNF may lead to embryonic death.

Constitutive overexpression of TNF in BPSM1 mice causes iBALT and bone marrow nodular lymphocytic hyperplasia.

BPSM1 (Bone phenotype spontaneous mutant 1) mice develop severe polyarthritis and heart valve disease as a result of a spontaneous mutation in the Tnf gene. In these mice, the insertion of a retrotransposon in the 3' untranslated region of Tnf causes a large increase in the expression of the cytokine. We have found that these mice also develop inducible bronchus-associated lymphoid tissue (iBALT), as well as nodular lymphoid hyperplasia (NLH) in the bone marrow. Loss of TNFR1 prevents the development of both types of follicles, but deficiency of TNFR1 in the hematopoietic compartment only prevents the iBALT and not the NLH phenotype. We show that the development of arthritis and heart valve disease does not depend on the presence of the tertiary lymphoid tissues. Interestingly, while loss of IL-17 or IL-23 limits iBALT and NLH development to some extent, it has no effect on polyarthritis or heart valve disease in BPSM1 mice.

Decreased MEFV gene expression in rheumatoid arthritis patients.

Rheumatoid arthritis (RA) is a major cause of adult chronic inflammatory arthritis and an autoimmune disease of unknown etiology in which the inflammatory pathology involves T cell activation. Genetic mutations in the Mediterranean fever (MEFV) gene, encoding pyrin, influence the severity of RA, but the underlying mechanisms are not completely understood. In this study, we investigated whether the full-length MEFV gene (MEFV-fl) and the exon 2-deleted splice isoform (MEFV-d2) expression are associated with or responsible for the clinical conditions of RA. This study include 47 patients with RA and 47 age- and gender-matched healthy controls. Quantitative real-time polymerase chain reaction analysis was performed to examine transcriptional changes in MEFV gene expression from peripheral blood samples. Reverse transcription-polymerase chain reaction of peripheral blood cells revealed the downregulation of MEFV-fl mRNA in non-treated patients compared with healthy controls and treated patients. MEFV-d2 expression was not different between groups. This is the first study to investigate the expression of MEFV transcript in RA. Deregulation of the MEFV gene is likely to result in uncontrolled inflammation as observed in RA. Therefore, downregulation of MEFV-fl may be involved in the pathogenesis of early-stage RA and treatment and may ameliorate MEFV-fl expression.

Genetic anomalies in patients with severe oligozoospermia and azoospermia in eastern Turkey: a prospective study.

Infertility is defined as the inability to conceive a child after one year of regular unprotected intercourse; it is a major health problem affecting about 10-15% of all couples. Infertility is due to a male factor in approximately 50% of cases. The human Y chromosome contains genes necessary for gonadal differentiation into a testis and genes for complete spermatogenesis. We examined the frequency and type of both chromosomal abnormalities and Y chromosome microdeletions in 90 patients with severe male factor infertility and 75 fertile control men. Thirty of the infertile patients had nonobstructive azoospermia, 30 had oligozoospermia and 30 had normozoospermia. Five of 30 were azoospermic, four of 30 were oligozoospermic and two of 30 were normozoospermic with Y chromosome microdeletions. The AZFc locus was the most frequently deleted region (64%). Ten cases with azoospermia, four cases with oligozoospermia and four cases with normozoospermia had chromosomal abnormalities. The 75 men with proven fertility were genetically normal. We conclude that various chromosomal abnormalities and deletions of the Y chromosome can cause infertility; therefore, genetic screening is indicated for infertile patients.