The heterogeneous
populations of exosomes with distinct nanosize
have impeded our understanding of their corresponding function as
intercellular communication agents. Profiling signaling proteins packaged
in each size-dependent subtype can disclose this heterogeneity of
exosomes. Herein, new strategy was developed for deconstructing heterogeneity
of distinct-size urine exosome subpopulations by profiling N-glycoproteomics
and phosphoproteomics simultaneously. Two-dimension size exclusion
liquid chromatography (SEC) was utilized to isolate large exosomes
(L-Exo), medium exosomes (M-Exo), and small exosomes (S-Exo) from
human urine samples. Then, hydrophilic carbonyl-functionalized magnetic
zirconium-organic framework (CFMZOF) was developed as probe for capturing
the two kinds of post-translational modification (PTM) peptides simultaneously.
Finally, liquid chromatography-tandem mass spectrometry (LC-MS/MS)
combined with database search was used to characterize PTM protein
contents. We identified 144 glycoproteins and 44 phosphoproteins from
L-Exo, 156 glycoproteins, and 46 phosphoproteins from M-Exo and 134
glycoproteins and 10 phosphoproteins from S-Exo. The ratio of the
proteins with simultaneous glycosylation and phosphorylation is 11%,
9%, and 3% in L-Exo, M-Exo, and S-Exo, respectively. Based on label-free
quantification intensity results, both principal component analysis
and Pearson’s correlation coefficients indicate that distinct-size
exosome subpopulations exist significant differences in PTM protein
contents. Analysis of high abundance PTM proteins in each exosome
subset reveals that the preferentially packaged PTM proteins in L-Exo,
M-Exo, and S-Exo are associated with immune response, biological metabolism,
and molecule transport processes, respectively. Our PTM proteomics
study based on size-dependent exosome subtypes opens a new avenue
for deconstructing the heterogeneity of exosomes.
BackgroundEach year in China, 30,000 babies are born with congenital hearing impairment. However, the molecular etiology of hearing impairment in the Yunnan Province population where more than 52 minorities live has not been thoroughly investigated. To provide appropriate genetic testing and counseling to these families, we investigated the molecular etiology of nonsyndromic deafness in this population.MethodsUnrelated students with hearing loss (n = 235) who attended Kunming Huaxia secondary specialized school in Yunnan enrolled in this study. Three prominent deafness-related genes, GJB2, SLC26A4 and mtDNA 12S rRNA, were analyzed. High-resolution temporal bone computed tomography (CT) scan examinations were performed in 100 cases, including 16 cases with SLC26A4 gene variants, and 37 minorities and 47 Han cases without any SLC26A4 gene mutation.ResultsThe GJB2 mutation was detected in 16.67% (7/42) of minority patients and 17.62% (34/193) of Chinese Han patients (P > 0.05). 235delC was the hotspot mutation in nonsyndromic hearing loss (NSHL) patients, whereas 35delG was not found. The 431_450del19 mutation was detected for the first time in Han NSHL patients, which resulted in a premature stop codon and changed the protein. The SLC26A4 mutation was found in 9.52% (4/42) of minority patients and 9.84% (19/193) of Han Chinese patients (P > 0.05). The frequencies of mtDNA 12S rRNA mutation in minority and Han Chinese patients were 11.90% (5/42) and 7.77% (15/193; P > 0.05), respectively. Sixteen (16/23, 69.57%) patients with SLC26A4 mutations received temporal bone CT scan, and 14 patients were diagnosed with enlarged vestibular aqueducts (EVAs); the other 2 patients had normal inner ear development. The ratio of EVA in the minorities was 14.63% (6/41).ConclusionsIn this study, a total of 35.74% deaf patients showed evidence of genetic involvement, based on either genetic screening or family history; 17.45%, 9.79%, and 8.51% of the patients were determined to have inherited hearing impairment caused by GJB2, SLC26A4, and mtDNA 1555A > G mutations. There was no significant difference in deafness associated gene mutational spectrum and frequency between the Yunnan minority and Han patients.
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