Genome-Wide Identification of Alternative Splice Forms Down-Regulated by Nonsense-Mediated mRNA Decay in Drosophila

Alternative mRNA splicing adds a layer of regulation to the expression of thousands of genes in Drosophila melanogaster. Not all alternative splicing results in functional protein; it can also yield mRNA isoforms with premature stop codons that are degraded by the nonsense-mediated mRNA decay (NMD) pathway. This coupling of alternative splicing and NMD provides a mechanism for gene regulation that is highly conserved in mammals. NMD is also active in Drosophila, but its effect on the repertoire of alternative splice forms has been unknown, as has the mechanism by which it recognizes targets. Here, we have employed a custom splicing-sensitive microarray to globally measure the effect of alternative mRNA processing and NMD on Drosophila gene expression. We have developed a new algorithm to infer the expression change of each mRNA isoform of a gene based on the microarray measurements. This method is of general utility for interpreting splicing-sensitive microarrays and high-throughput sequence data. Using this approach, we have identified a high-confidence set of 45 genes where NMD has a differential effect on distinct alternative isoforms, including numerous RNA–binding and ribosomal proteins. Coupled alternative splicing and NMD decrease expression of these genes, which may in turn have a downstream effect on expression of other genes. The NMD–affected genes are enriched for roles in translation and mitosis, perhaps underlying the previously observed role of NMD factors in cell cycle progression. Our results have general implications for understanding the NMD mechanism in fly. Most notably, we found that the NMD–target mRNAs had significantly longer 3′ untranslated regions (UTRs) than the nontarget isoforms of the same genes, supporting a role for 3′ UTR length in the recognition of NMD targets in fly

ICAR: endoscopic skull‐base surgery

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The cardiovascular system in growth hormone excess and growth hormone deficiency.

The clinical conditions associated with GH excess and GH deficiency (GHD) are known to be associated with an increased risk for the cardiovascular morbidity and mortality, suggesting that either an excess or a deficiency in GH and/or IGF-I is deleterious for cardiovascular system. In patients with acromegaly, chronic GH and IGF-I excess commonly causes a specific cardiomyopathy characterized by a concentric cardiac hypertrophy associated with diastolic dysfunction and, in later stages, with systolic dysfunction ending in heart failure if GH/IGF-I excess is not controlled. Abnormalities of cardiac rhythm and anomalies of cardiac valves can also occur. Moreover, the increased prevalence of cardiovascular risk factors, such as hypertension, diabetes mellitus, and insulin resistance, as well as dyslipidemia, confer an increased risk for vascular atherosclerosis. Successful control of the disease is accompanied by a decrease of the cardiac mass and improvement of cardiac function and an improvement in cardiovascular risk factors. In patients with hypopituitarism, GHD has been considered the underlying factor of the increased mortality when appropriate standard replacement of the pituitary hormones deficiencies is given. Either childhood-onset or adulthood-onset GHD are characterized by a cluster of abnormalities associated with an increased cardiovascular risk, including altered body composition, unfavorable lipid profile, insulin resistance, endothelial dysfunction and vascular atherosclerosis, a decrease in cardiac mass together with an impairment of systolic function mainly after exercise. Treatment with recombinant GH in patients with GHD is followed by an improvement of the cardiovascular risk factors and an increase in cardiac mass together with an improvement in cardiac performance. In conclusion, acromegaly and GHD are associated with an increased risk for cardiovascular morbidity and mortality, but the control of GH/IGF-I secretion reverses cardiovascular abnormalities and restores the normal life expectancy

Clinical outcome and evidence of high rate post-surgical anterior hypopituitarism in a cohort of TSH-secreting adenoma patients: Might somatostatin analogs have a role as first-line therapy?

PURPOSE: Thyrotropin-secreting pituitary adenomas (TSHomas) represent a rare subtype of pituitary tumors. Neurosurgery (NCH) is still considered the first-line therapy. In this study we aimed to investigate the outcome of different treatment modalities, including first line somatostatin analogs (SSA) treatment, with a specific focus on neurosurgery-related complications. METHODS: We retrospectively evaluated thirteen patients diagnosed for TSHomas (9 M; age range 27-61). Ten patients had a magnetic resonance evidence of macroadenoma, three with slight visual field impairment. In the majority of patients, thyroid ultrasonography showed the presence of goiter and/or increased gland vascularization. Median TSH value at diagnosis was 3.29 mU/L (normal ranges 0.2-4.2 mIU/L), with median fT4 2.52 ng/dL (0.9-1.7 ng/dL). RESULTS: Three patients (two microadenoma) were primarily treated with NCH and achieved disease remission, whereas ten patients (nine macroadenomas) were initially treated with SSA. Despite the optimal biochemical response observed during medical treatment in most patients (mean TSH decrease -72 %), only two stayed on medical therapy alone, achieving stable biochemical control at the end of the follow-up. The remaining patients (n = 7) underwent NCH later on during their clinical history, followed by radiotherapy or adjuvant SSA treatment in two cases. Noteworthy, five of them developed hypopituitarism. All patients reached a biochemical control, after a multimodal therapeutic approach. CONCLUSIONS: Neurosurgery ultimately led to complete disease remission or to biochemical control in majority of patients, whereas resulting in a considerable percentage of post-operative complications (mainly hypopituitarism, 50 %). In the light of the optimal results unanimously reported for medical treatment with SSA, our experience suggests that a careful evaluation of risk/benefit ratio should be taken into consideration when directing the treatment approach in patients with TSHoma