ABSTRACT
The abundance of proteins in human urine is low and easily to be masked by high-abundance proteins during mass spectrometry analysis. Development of efficient and highly selective enrichment methods is therefore a prerequisite for achieving deep coverage of urine protein markers. Notably, different experimental methods would affect the urine protein enrichment efficacy and the coverage of urine proteome. In this study, ultrafiltration, nitrocellulose membrane enrichment and saturated ammonium sulfate precipitation were used to process 10 mL urine samples from five healthy volunteers and five bladder cancer patients. The urine proteins were enriched and separate by SDS-PAGE to compare the purification efficiency of different methods. Moreover, the peptide identification effects of different purification methods were analyzed by mass spectrometry to determine the best method for enriching urine protein histones. Saturated ammonium sulfate precipitation method outperformed the ultrafiltration and the nitrocellulose membrane enrichment methods in terms of the protein enrichment efficacy and quality. The interference of highly abundant albumin was reduced, whereas the amount of low-abundance protein was increased, and the sensitivity of mass spectrometry identification was increased. The saturated ammonium sulfate precipitation method may be applied for large-scale urine processing for screening clinical diagnostic markers through proteomics.
Subject(s)
Humans , Histones , Mass Spectrometry , Proteome , Proteomics , UrinalysisABSTRACT
Biomarkers are the detectable changes associated with physiological or pathological changes. Urine as excreta of the body, without the mechanisms to maintain a homeostatic internal environment, can reflect a variety of changes in the body. Using animal models can simulate human disease processes, monitor disease changes, and provide clues to early diagnosis. Rats as commonly used model animals are not the dominant models for all disease, thus comparing the urinary proteins of rats with other animals to provide clues to the selection of other animal dominant models. In this study, urinary proteins were digested and profiled by liquid chromatography and tandem mass spectrometry (LC-MS/MS). The urinary proteins of rats, guinea pigs and golden hamsters were compared. The results showed that the number of urine proteins in the three different animals was different, and also different in every system of the body. This provides a basis for selecting the best animal models for different diseases.
ABSTRACT
PURPOSE: Interstitial cystitis/painful bladder syndrome (IC/PBS) is characterized by chronic pain, pressure and discomfort felt in the pelvis or bladder. An in-depth shotgun proteomics study was carried out to profile the urinary proteome of women with IC/PBS to identify possible specific proteins and networks associated with IC/PBS. MATERIALS AND METHODS: Urine samples from ten female IC/PBS patients and ten female asymptomatic, healthy control subjects were analyzed in quadruplicate by liquid chromatography-tandem mass spectrometry (LC-MS/MS) on a hybrid linear ion trap-orbitrap mass spectrometer. Gas-phase fractionation (GPF) was used to enhance protein identification. Differences in protein quantity were determined by peptide spectral counting. RESULTS: a-1B-glycoprotein (A1BG) and orosomucoid-1 (ORM1) were detected in all IC/PBS patients, and = 60 percent of these patients had elevated expression of these two proteins compared to control subjects. Transthyretin (TTR) and hemopexin (HPX) were detected in all control individuals, but = 60 percent of the IC/PBS patients had decreased expression levels of these two proteins. Enrichment functional analysis showed cell adhesion and response to stimuli were down-regulated whereas response to inflammation, wounding, and tissue degradation were up-regulated in IC/PBS. Activation of neurophysiological processes in synaptic inhibition, and lack of DNA damage repair may also be key components of IC/PBS. CONCLUSION: There are qualitative and quantitative differences between the urinary proteomes of women with and without IC/PBS. We identified a number of proteins as well as pathways/networks that might contribute to the pathology of IC/PBS or result from perturbations induced by this condition.