The role of glycosylation in amyloid fibril formation of bovine κ-casein

Integrative genomics unveils basement membrane-related diagnostic markers and therapeutic targets in esophageal squamous cell carcinoma

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) is often diagnosed at advanced stages due to the inherent limitations of current screening methodologies. Central to evaluating tumor invasion and prognostic assessment in ESCC is the integrity of the basement membrane (BM). However, current research on the implications of BM-related genes (BMRGs) in diagnosing ESCC remains sparse.

METHODS

We performed a comprehensive analysis using single-cell RNA-sequencing (scRNA-seq) data from the Gene Expression Omnibus (GEO) database, alongside gene expression profiles acquired from GEO and The Cancer Genome Atlas (TCGA) databases. This identified differentially expressed BMRGs in ESCC. Employing LASSO, RF, and SVM-RFE, we selected potential BM biomarkers and crafted a diagnostic nomogram for ESCC, validated by ROC curves and AUC values. We also explored immune infiltration and biological mechanisms through consensus clustering and GSVA, and utilized single cell trajectory analysis and GSCALite to study gene distributions and pathways. In vitro experiments further elucidated the role of these genes in ESCC carcinogenesis.

RESULTS

Here, we discovered that ESCC cell types exhibited markedly elevated BM-related scores. Our analysis pinpointed seven BM genes upregulated and linked to immune infiltration, showcasing unique gene expression profiles and varying immune cell densities across the BM-related subtypes. Furthermore, a robust positive correlation was observed between these genes expression and EMT activity. The knockdown of BGN significantly suppressed cell proliferation, migration, invasion, while also augmenting cell viability following chemotherapy drug treatment.

CONCLUSION

Our study identified seven key BMRGs (BGN, LAMB3, SPARC, MMP1, LUM, COL4A1, and NELL2) and established a diagnostic nomogram for ESCC. Of noteworthy significance is the discovery of BGN as a promising drug target, indicating a novel strategy for future clinical combination therapies in ESCC.

Invited review: Modeling milk stability

Novel insights into the stability of milk and milk products during storage and processing result from describing caseins near neutral pH as hydrophilic, intrinsically disordered, proteins. Casein solubility is strongly influenced by pH and multivalent ion binding. Solubility is high at a neutral pH or above, but decreases as the casein net charge approaches zero, allowing a condensed casein phase or gel to form, then increases at lower pH. Of particular importance for casein micelle stability near neutral pH is the proportion of free caseins in the micelle (i.e., caseins not bound directly to nanoclusters of calcium phosphate). Free caseins are more soluble and better able to act as molecular chaperones (to prevent casein and whey protein aggregation) than bound caseins. Some free caseins are highly phosphorylated and can also act as mineral chaperones to inhibit the growth of calcium phosphate phases and prevent mineralized deposits from forming on membranes or heat exchangers. Thus, casein micelle stability is reduced when free caseins bind to amyloid fibrils, destabilized whey proteins or calcium phosphate. The multivalent-binding model of the casein micelle quantitatively describes these and other factors affecting the stability of milk and milk protein products during manufacture and storage.

Effect of composition, casein genetic variants and glycosylation degree on bovine milk whipping properties

This study investigated the individual and combined effects of ĸ-Casein (ĸ-CN; AA, AB, BB), β-Casein (β-CN; A1A1, A1A2, A2A2) and high and low ratios of glycosylated ĸ-CN to total ĸ-CN, referred to as the glycosylation degree (GD), on bovine cream whipping properties. The genetic variants of individual cows were identified using reversed-phase high-performance liquid chromatography (RP-HPLC) and verified through liquid chromatography-mass spectrometry (LC-MS). A previously discovered relationship between days-in-milk and GD was validated and used to obtain high and low GD milk. Whipped creams were created through the mechanical agitation of fat standardised cream from milk of different ĸ-CN, β-CN, and GD combinations, and whipping properties (the ability to whip, overrun, whipping time and firmness) were evaluated. No significant correlation was measured in whipping properties for cream samples from milks with different ĸ-CN and β-CN genetic variants. However, 80 % of samples exhibiting good whipping properties (i.e., the production of a stiffened peak) were from milk with low GD suggesting a correlation between whipping properties and levels of glycosylation. Moreover, cream separated from skim milk of larger casein micelle size showed superior whipping properties with shorter whipping times (<5 min), and higher firmness and overrun. Milk fat globule (MFG) size, on the other hand, did not affect whipping properties. Results indicate that the GD of κ-CN and casein micelle size may play a role in MFG adsorption at the protein and air interface of air bubbles formed during whipping; hence, they govern the dynamics of fat network formation and influencing whipping properties.