Single-cell omics analyses with single molecular detection: challenges and perspectives

Native N-glycome profiling of single cells and ng-level blood isolates using label-free capillary electrophoresis-mass spectrometry

The development of reliable single-cell dispensers and substantial sensitivity improvement in mass spectrometry made proteomic profiling of individual cells achievable. Yet, there are no established methods for single-cell glycome analysis due to the inability to amplify glycans and sample losses associated with sample processing and glycan labeling. In this work, we present an integrated platform coupling online in-capillary sample processing with high-sensitivity label-free capillary electrophoresis-mass spectrometry for N-glycan profiling of single mammalian cells. Direct and unbiased quantitative characterization of single-cell surface N-glycomes are demonstrated for HeLa and U87 cells, with the detection of up to 100 N-glycans per single cell. Interestingly, N-glycome alterations are unequivocally detected at the single-cell level in HeLa and U87 cells stimulated with lipopolysaccharide. The developed workflow is also applied to the profiling of ng-level amounts (5-500 ng) of blood-derived protein, extracellular vesicle, and total plasma isolates, resulting in over 170, 220, and 370 quantitated N-glycans, respectively.

Galectin-14 promotes hepatocellular carcinoma tumor growth via enhancing heparan sulfate proteoglycan modification

Hepatocellular carcinoma (HCC) is a highly heterogeneous malignancy and lacks effective treatment. Bulk-sequencing of different gene transcripts by comparing HCC tissues and adjacent normal tissues provides some clues for investigating the mechanisms or identifying potential targets for tumor progression. However, genes that are exclusively expressed in a subpopulation of HCC may not be enriched or detected through such a screening. In the current study, we performed a single cell-clone-based screening and identified galectin-14 as an essential molecule in the regulation of tumor growth. The aberrant expression of galectin-14 was significantly associated with a poor overall survival of liver cancer patients with database analysis. Knocking down galectin-14 inhibited the proliferation of tumor growth, whereas overexpressing galectin-14 promoted tumor growth in vivo. Non-targeted metabolomics analysis indicated that knocking down galectin-14 decreased glycometabolism; specifically that glycoside synthesis was significantly changed. Further study found that galectin-14 promoted the expression of cell surface heparan sulfate proteoglycans (HSPGs) that functioned as co-receptors, thereby increasing the responsiveness of HCC cells to growth factors, such as epidermal growth factor and transforming growth factor-alpha. In conclusion, the current study identifies a novel HCC-specific molecule galectin-14, which increases the expression of cell surface HSPGs and the uptake of growth factors to promote HCC cell proliferation.

In-capillary sample processing coupled to label-free capillary electrophoresis-mass spectrometry to decipher the native N-glycome of single mammalian cells and ng-level blood isolates

The development of reliable single-cell dispensers and substantial sensitivity improvement in mass spectrometry made proteomic profiling of individual cells achievable. Yet, there are no established methods for single-cell glycome analysis due to the inability to amplify glycans and sample losses associated with sample processing and glycan labeling. In this work, we developed an integrated platform coupling online in-capillary sample processing with high-sensitivity label-free capillary electrophoresis-mass spectrometry for N-glycan profiling of single mammalian cells. Direct and unbiased characterization and quantification of single-cell surface N-glycomes were demonstrated for HeLa and U87 cells, with the detection of up to 100 N-glycans per single cell. Interestingly, N-glycome alterations were unequivocally detected at the single-cell level in HeLa and U87 cells stimulated with lipopolysaccharide. The developed workflow was also applied to the profiling of ng-level amounts of blood-derived protein, extracellular vesicle, and total plasma isolates, resulting in over 170, 220, and 370 quantitated N-glycans, respectively.

Immunometabolic alterations in lupus: where do they come from and where do we go from there?

Systemic lupus erythematosus (SLE) is an autoimmune disease in which the overactivation of the immune system has been associated with metabolic alterations. Targeting the altered immunometabolism has been proposed to treat SLE patients based on their results obtained and mouse models of the disease. Here, we review the recent literature to discuss the possible origins of the alterations in the metabolism of immune cells in lupus, the dominant role of mitochondrial defects, technological advances that may move the field forward, as well as how targeting lupus immunometabolism may have therapeutic potential.