The Interaction between Collagen 1 and High Mannose Type CD133 Up-Regulates Glutamine Transporter SLC1A5 to Promote the Tumorigenesis of Glioblastoma Stem Cells.

Targeting the niche components surrounding glioblastoma stem cells (GSCs) helps to develop more effective glioblastoma treatments. However, the mechanisms underlying the crosstalk between GSCs and microenvironment remain largely unknown. Clarifying the extracellular molecules binding to GSCs marker CD133 helps to elucidate the mechanism of the communication between GSCs and the microenvironment. Here, it is found that the extracellular domain of high mannose type CD133 physically interacts with Collagen 1 (COL1) in GSCs. COL1, mainly secreted by cancer-associated fibroblasts, is a niche component for GSCs. COL1 enhances the interaction between CD133 and p85 and activates Akt phosphorylation. Activation of Akt pathway increases transcription factor ATF4 protein level, subsequently enhances SLC1A5-dependent glutamine uptake and glutathione synthesis. The inhibition of CD133-COL1 interaction or down-regulation of SLC1A5 reduces COL1-accelerated GSCs self-renewal and tumorigenesis. Analysis of glioma samples reveals that the level of COL1 is correlated with histopathological grade of glioma and the expression of SLC1A5. Collectively, COL1, a niche component for GSCs, enhances the tumorigenesis of GSCs partially through CD133-Akt-SLC1A5 signaling axis, providing a new mechanism underlying the cross-talk between GSCs and extracellular matrix (ECM) microenvironment.

Comparative Analysis of Free and Glycoconjugates Oligosaccharide Content in Milk from Different Species.

Human milk is important for infant growth, and oligosaccharides are one of its main functional nutrients. To enable a systematic comparison of free oligosaccharide and glycoconjugate content in milk from different species, the phenol-sulfuric acid and resorcinol assays were combined to determine the content. Using real samples, the method revealed that human milk contained the highest amount of total, neutral (9.84 ± 0.31 g/L), and sialylated (3.21 ± 0.11 g/L) free oligosaccharides, followed by goat milk, with neutral (0.135 ± 0.015 g/L) and sialylated (0.192 ± 0.016 g/L) free oligosaccharides and at a distance by bovine and yak milk. The highest total glycoconjugate content was detected in yak milk (0.798 ± 0.011 g/L), followed by human, bovine, and goat milk. These findings suggest that goat milk is the best source of free oligosaccharides in infant formula and functional dairy products and yak milk is the best source of glycoconjugates.

Siglec15 promotes the migration of thyroid carcinoma cells by enhancing the EGFR protein stability.

PURPOSE: Sialic acid-bound immunoglobulin-like lectin 15 (Siglec15) has emerged as a novel therapeutic target in tumor immunotherapy. This study is designed to investigate the function and mechanism of Siglec15 in thyroid carcinoma (THCA). MATERIALS AND METHODS: The information on patients with THCA from TGCA and GEO database were used to analyze the expression of Siglec15 in THCA. THCA cells were treated with Siglec15-mFc, a recombinant fusion protein consisting of the extracellular domain of human Siglec15 and murine IgG Fc. THP-1 cells expressing human Siglec15 and its mutant were co-cultured with THCA cells to mimic the contact between Siglec15-expressing tumor-associated macrophages and THCA cells. Wound-healing assay and transwell migration assay were used to examine the migration abilities of BCPAP and C643 cells. Pull-down assay was performed to examine the interaction between Siglec15 and epidermal growth factor receptor (EGFR) on the cancer cells. Cycloheximide (CHX) assay was used to evaluate the stability of the protein. RESULTS: The expression of Siglec15 in thyroid carcinoma tissues is higher than in normal tissues. Siglec15 promotes the migration of THCA cells by binding to EGFR in a sialic acid-dependent manner and increases EGFR protein expression. Inhibition of the EGFR pathway blocks the effect of Siglec15 on the migration of THCA cells. CONCLUSIONS: Our findings reveals that Siglec15 promotes the migration of thyroid carcinoma cells by enhancing the EGFR protein stability.

Comparative analysis of yak milk and bovine milk glycoprotein N/O-glycome by online HILIC-UV-ESI-MS/MS.

Yak milk (YM) has higher protein content than other bovine milk (BM) varieties. The bioactivity of milk glycoproteins is related to N/O-glycans. We qualitatively and quantitatively compared the N/O-glycome of YM and BM glycoproteins using stable isotope labeling combined with hydrophilic interaction chromatography and electrospray ionization mass spectrometry. We identified 79 and 78 N-glycans in YM and BM, respectively. Two N-glycans (H4N5F1A1; H5N4F1) were exclusive to YM. The content ratios of different types of N-glycans differed significantly between YM and BM, with sialylated N-glycans 2.33 times more abundant in YM. Five and seven O-glycans were detected in YM and BM, respectively. Two O-glycans (H1N2; H1N2A1) were exclusive to BM. The bi-sialylated O-glycan, H1N1A2, accounted for 56.1% of O-glycans in YM; it was 5.97 times more abundant in YM than in BM (equal volume basis). This study provides a theoretical basis for the future utilization of YM as a functional food.

Alteration of the goat milk glycoproteins N/O-glycome at different lactation stages.

Goat milk oligosaccharides represent an unexplored multi-functional ingredient for the dairy industry. Here, we qualitatively and quantitatively compared the N/O-glycome at different lactation stages via online hydrophilic interaction chromatography-tandem mass spectrometry. Complex N-glycans and high mannose N-glycans constituted 82.1% and 17.9% of the glycan pool, respectively. N-glycans with isomers containing non-bisected antenna complex structures accounted for 30.8%. N-glycans modified with Neu5Ac, Neu5Gc and fucosylated were 3.7%, 5.3% and 35.3%. The triantennary trifucosylated complex N-glycan (H5N5F3) was reported for the first time. A comparison between colostrum and mature milk revealed a 1.20-fold decrease in total N-glycans and 1.66-fold decrease in fucosylation with ongoing lactation, echoing the trend in human milk. Similarly, Neu5Ac- and Neu5Gc-modified sialylation decreased by 1.69 and 3.62 times, respectively. In the O-glycome, 46.2% of structures were O-linked core 1, 23.1% were O-linked core 2, 7.7% were O-linked core 3 and core 4. As lactation progressed, overall O-glycans content decreased by 1.26-fold. Unlike human milk, Neu5Ac- and Neu5Gc-modified sialylation increased by 4.4 and 2 times, respectively. These findings will facilitate research on the structure-function relationship of goat milk oligosaccharides and the development of formula food targeting different age groups.

Online LC-UV-ESI-MS/MS Comparative Analysis of Changes in Goat Colostrum N/O-Glycopatterns at Different Parities.

Goat milk oligosaccharides are complex carbohydrates with a variety of biological functions. Free oligosaccharides from goat milk show more similarity to human milk than cow milk. At present, changes in goat milk glycoconjugates at different parities remain poorly studied. Herein, we qualitatively and quantitatively compared the goat milk glycoprotein N/O-glycome at different parities using a stable isotope labeling followed by electrospray ionization mass spectrometry and online hydrophilic interaction chromatography. N-Glycans were mainly fucosylated and nonfucosylated nonsialylated, and both fucosylation and sialylation gradually increased with parity, amounting (at the third parity) to 1.25 times and 3.3 times those of the first parity, respectively. O-Glycans were mostly nonfucosylated and nonsialylated, and sialylation increased with increasing parity, and Neu5Ac-sialylated was up to 9 times higher in the third parity than in the first parity, whereas Neu5Gc-sialylated was 5.5 times higher. This study provides a reference for exploring an alternative milk source closest to human milk and for the development of humanized formula milk.

Mass Spectrometry Analysis of Changes in Human Milk N/O-Glycopatterns at Different Lactation Stages.

Human milk oligosaccharides are complex carbohydrates with multibiofunctional health benefits to newborns. Human milk free oligosaccharides (HMOs) are well characterized. However, changes in the N/O-glycome during lactation are poorly reported. Herein, we qualitatively and quantitatively investigated N/O-glycome profiles and their alteration in human milk at different lactation stages. N-Glycans were mainly fucosylated and nonsialylated, nonfucosylated throughout lactation. O-Glycans mainly consisted of sialylated and nonsialylated, nonfucosylated in colostrum and transitional milk, and fucosylated and nonfucosylated, nonsialylated in mature milk. Fucosylated and sialylated N-glycans gradually decreased and increased, respectively, as lactation progressed; O-glycans showed the reverse. Interestingly, changes in HMO abundance decreased during lactation, complementing HMG N/O-glycome changes. In conclusion, temporal HMG glycosylation changes provide the groundwork for developing infant formula that is closer to breast milk at different lactation stages.