Genetically polymorphic alpha-L-fucosidase (FUCA1) isozymes detected in blood plasma

Molecularly Targeted Fluorescent Sensors for Visualizing and Tracking Cellular Senescence

Specific identification and monitoring of senescent cells are essential for the in-depth understanding and regulation of senescence-related life processes and diseases. Fluorescent sensors providing real-time and in situ information with spatiotemporal resolution are unparalleled tools and have contributed greatly to this field. This review focuses on the recent progress in fluorescent sensors for molecularly targeted imaging and real-time tracking of cellular senescence. The molecular design, sensing mechanisms, and biological activities of the sensors are discussed. The sensors are categorized by the types of markers and targeting ligands. Accordingly, their molecular recognition and fluorescent performance towards senescence biomarkers are summarized. Finally, the perspective and challenges in this field are discussed, which are expected to assist future design of next-generation sensors for monitoring cellular senescence.

Dual role of fucosidase in cancers and its clinical potential

Glycosidases and glycosyltransferases greatly impact malignant phenotype of tumors though genetics and epigenetics mechanisms. As the member of glycoside hydrolase (GH) families 29A, α-L-fucosidases (AFUs) are involved in the hydrolysis of terminal L-fucose residues linked via α-1,2, α-1,3, α-1,4 or α-1,6 to the reducing end of N-acetyl glucosamine (GlcNAc) of oligosaccharide chains. The defucosylation process mediated by AFUs contributes to the development of various diseases, such as chronic inflammatory diseases, immune disorders, and autoimmune diseases by reducing the interaction between fucosylated adhesion molecules supporting leukocyte extravasation. AFUs also impair crucial cell-extracellular matrix (ECM) interactions and presumably subsequent cell signaling pathways, which lead to changes in tumor function and behavior. There are two isoforms of AFUs in human, namely α-L-fucosidase 1 (FUCA1) and α-L-fucosidase 2 (FUCA2), respectively. FUCA1 is a p53 target gene and can hydrolyze different fucosylation sites on epidermal growth factor receptor (EGFR), thereby determining the activation of EGFR. FUCA2 mediates the adhesion between Helicobacter pylori and gastric mucosa and is upregulated in 24 tumor types. Besides, based on the participation of AFU in signaling pathways and tumor progression, we discuss the prospect of AFU as a therapeutic target.

Harnessing α-l-fucosidase for in vivo cellular senescence imaging

Precise detection of cellular senescence may allow its role in biological systems to be evaluated more effectively, while supporting studies of therapeutic candidates designed to evade its detrimental effect on physical function. We report here studies of α-l-fucosidase (α-fuc) as a biomarker for cellular senescence and the development of an α-fuc-responsive aggregation induced emission (AIE) probe, termed QM-NHαfuc designed to complement more conventional probes based on β-galactosidase (β-gal). Using QM-NHαfuc, the onset of replicative-, reactive oxygen species (ROS)-, ultraviolet A (UVA)-, and drug-induced senescence could be probed effectively. QM-NHαfuc also proved capable of identifying senescent cells lacking β-gal expression. The non-invasive real-time senescence tracking provided by QM-NHαfuc was validated in an in vivo senescence model. The results presented in this study lead us to suggest that the QM-NHαfuc could emerge as a useful tool for investigating senescence processes in biological systems.

Evidence of close association of α-fuc with senescence induction highlights the potential of α-fuc as a novel biomarker for cellular senescence. Here, an α-fuc-responsive AIE probe (QM-NHαfuc) allows for the identification of senescent cell in vivo.

Cell surface human alpha-L-fucosidase

The acid alpha-L-fucosidase is usually found as a soluble component of lysosomes where fucoglycoconjugates are degraded. In the present investigation, we have demonstrated the existence of a cell surface protein with enzymatic alpha-L-fucosidase activity that crossreacts specifically with a rabbit anti-(alpha-L-fucosidase) Ig. By different approaches, this alpha-L-fucosidase, which represents 10-20% of the total cellular fucosidase activity, was detected in all the tested human cells (hemopoietic, epithelial, mesenchymal). Two bands of approximately 43-49 kDa were observed, although theoretical data support the possibility of having the same genetic origin that the known 50 to 55-kDa Mr alpha-L-fucosidase. We speculate about an alternative traffic pathway for the plasma membrane alpha-L-fucosidase to work on the rapid turnover of glycoproteins.

Forensic applications of genetic polymorphisms detected in human body fluids (urine, semen and blood)

The development of a new genetic marker with forensic usefulness is difficult and costly work, but it is necessary. We discovered several new markers detected in urine, semen and blood. In particular, deoxyribonuclease I-polymorphism is one of the most useful markers for practical purposes, since it has a well-balanced gene frequency, high concentration in body fluids, stability against severe conditions, and easy and accurate detectability.