Alternative splicing (AS) of protein-coding messenger RNAs is an essential regulatory mechanism in eukaryotic gene expression that controls the proper function of proteins. It is also implicated in the physiological regulation of mitochondria and various ion channels. Considering that mis-splicing can result in various human diseases by modifying or abrogating important physiological protein functions, a fine-tuned balance of AS is essential for human health. Accumulated data highlight the importance of alternatively spliced isoforms in various diseases, including neurodegenerative disorders, cancer, immune and infectious diseases, cardiovascular diseases, and metabolic conditions. However, basic understanding of disease mechanisms and development of clinical applications still require the integration and interpretation of physiological roles of AS. This review discusses the roles of AS in health and various diseases, while highlighting potential AS-targeting therapeutic applications.

Aims Little is known about the prevalence of aortic aneurysms among people living with HIV (PLWH). We investigated whether HIV status is independently associated with having aortic aneurysms. Furthermore, we determined risk factors associated with aortic aneurysms in PLWH. Methods and results PLWH aged ≥40 years (n = 594) were recruited from the Copenhagen Comorbidity in HIV Infection study and matched for age and sex with uninfected controls (n = 1188) from the Copenhagen General Population Study. Aortic dimensions were assessed using contrast enhanced computed tomography. Aortic aneurysms were defined according to the European Society of Cardiology guidelines, i.e. an aortic dilation of ≥50% or an infrarenal aortic diameter of ≥30 mm. Among PLWH and uninfected controls, the median (interquartile range) age was 52 (47–60) and 52 (48–61) and 88% and 90% were male, respectively. We found 46 aneurysms in 42 (7.1%) PLWH and 31 aneurysms in 29 (2.4%) uninfected controls (P < 0.001). PLWH had a significantly higher prevalence of ascending aortic aneurysms and infrarenal aortic aneurysms. In an adjusted model, HIV was independently associated with aortic aneurysms (adjusted odds ratio; 4.51 [95% confidence interval 2.56–8.08], P < 0.001). Within PLWH, obesity and hepatitis B co-infection were associated with aortic aneurysms. Conclusion PLWH had four-fold higher odds of aortic aneurysms compared to uninfected controls, and HIV status was independently associated with aortic aneurysms. Among PLWH, age, obesity and hepatitis B co-infection were associated with higher odds of aortic aneurysms. Our findings suggest that increased attention to aortic aneurysms in PLWH may be beneficial.

BackgroundA critical need exists to better understand the physiological sequel of vitamin D supplementation in obese individuals and African Americans. The aim was to comprehensively evaluate dose- and time-responses of a panel of vitamin D biomarkers to vitamin D supplements in this population.MethodsWe conducted a 16-week randomized, double-blinded, and placebo-controlled clinical trial. Seventy overweight/obese African Americans (age 13–45 years, 84 % females) with 25-hydroxyvitamin D [25(OH)D] concentrations ≤20 ng/mL were randomly assigned to receive a supervised monthly oral vitamin D3 of 18,000 IU (~600 IU/day, n = 17), 60,000 IU (~2000 IU/day, n = 18), 120,000 IU (~4000 IU/day, n = 18), or placebo (n = 17).ResultsThere were significant dose- and time-responses of circulating 25(OH)D, 1,25-dihydroxyvitamin D [1,25(OH)2D], and intact parathyroid hormone (iPTH), but not fibroblast growth factor-23 (FGF-23), phosphorus and urine calcium to the vitamin D supplements. The mean 25(OH)D concentrations in the 2000 IU and 4000 IU groups reached ≥30 ng/mL as early as 8-weeks and remained at similar level at 16-weeks. The increase of 25(OH)D was significantly higher in the 4000 IU group than all the other groups at 8-weeks. The increase of 1,25(OH)2D was significantly higher in the 2000 IU and 4000 IU groups than the placebo at 8-weeks. Only the 4000 IU compared to the placebo significantly reduced iPTH at 8- and 16-weeks.ConclusionsOur RCT, for the first time, comprehensively evaluated time- and dose- responses of vitamin D supplementation in overweight/obese African Americans with suboptimal vitamin D status. Circulating 25(OH)D, 1,25(OH)2D, and iPTH, but not FGF-23, phosphorus and urine calcium, respond to vitamin D supplementation in a time- and dose–response manner. By monthly dosing, 2000 IU appears to be sufficient in achieving a 25(OH)D level of 30 ng/mL in this population. However, importantly, 4000 IU, rather than 2000 IU, seems to suppress iPTH. If replicated, these data might be informative in optimizing vitamin D status and providing individualized dosing recommendation in overweight/obese African Americans.Trial registrationClinicalTrials.gov number: NCT01583621, Registered on April 3, 2012.