Cell Adhesion Molecules and Ubiquitination-Functions and Significance

N-BAR and F-BAR proteins-endophilin-A3 and PSTPIP1-control clathrin-independent endocytosis of L1CAM

Recent advances in the field demonstrate the high diversity and complexity of endocytic pathways. In the current study, we focus on the endocytosis of L1CAM. This glycoprotein plays a major role in the development of the nervous system, and is involved in cancer development and is associated with metastases and poor prognosis. Two L1CAM isoforms are subject to endocytosis: isoform 1, described as a clathrin-mediated cargo; isoform 2, whose endocytosis has never been studied. Deciphering the molecular machinery of isoform 2 internalisation should contribute to a better understanding of its pathophysiological role. First, we demonstrated in our cellular context that both isoforms of L1CAM are mainly a clathrin-independent cargo, which was not expected for isoform 1. Second, the mechanism of L1CAM endocytosis is specifically mediated by the N-BAR domain protein endophilin-A3. Third, we discovered PSTPIP1, an F-BAR domain protein, as a novel actor in this endocytic process. Finally, we identified galectins as endocytic partners and negative regulators of L1CAM endocytosis. In summary, the interplay of the BAR proteins endophilin-A3 and PSTPIP1, and galectins fine tune the clathrin-independent endocytosis of L1CAM.

Altering Cell-Cell Interaction in Prenatal Alcohol Exposure Models: Insight on Cell-Adhesion Molecules During Brain Development

Alcohol exposure during pregnancy disrupts the development of the brain and produces long lasting behavioral and cognitive impairments collectively known as Fetal Alcohol Spectrum Disorders (FASDs). FASDs are characterized by alterations in learning, working memory, social behavior and executive function. A large body of literature using preclinical prenatal alcohol exposure models reports alcohol-induced changes in architecture and activity in specific brain regions affecting cognition. While multiple putative mechanisms of alcohol’s long-lasting effects on morphology and behavior have been investigated, an area that has received less attention is the effect of alcohol on cell adhesion molecules (CAMs). The embryo/fetal development represents a crucial period for Central Nervous System (CNS) development during which the cell-cell interaction plays an important role. CAMs play a critical role in neuronal migration and differentiation, synaptic organization and function which may be disrupted by alcohol. In this review, we summarize the physiological structure and role of CAMs involved in brain development, review the current literature on prenatal alcohol exposure effects on CAM function in different experimental models and pinpoint areas needed for future study to better understand how CAMs may mediate the morphological, sensory and behavioral outcomes in FASDs.

Magnetic Resonance Imaging of Perineural Spread of Head and Neck Cancer

Perineural tumor spread (PNTS) is one of the important methods of tumoral spread in head and neck cancers. It consists of a complex process that entails the production of certain chemicals or the production of certain cell receptors. Histologic type and primary tumor site play an important role in PNTS. Any nerve could be affected; however, the trigeminal and facial nerves are the most involved nerves. Magnetic resonance imaging and computed tomography detect the primary and secondary signs of PNTS. Functional imaging such as diffusion-weighted imaging and hybrid imaging act as problem-solving techniques.

NEDD4 regulates ubiquitination and stability of the cell adhesion molecule IGPR-1 via lysosomal pathway

Background

The cell adhesion molecule IGPR-1 regulates various critical cellular processes including, cell–cell adhesion, mechanosensing and autophagy and plays important roles in angiogenesis and tumor growth; however, the molecular mechanism governing the cell surface levels of IGPR-1 remains unknown.

Results

In the present study, we used an in vitro ubiquitination assay and identified ubiquitin E3 ligase NEDD4 and the ubiquitin conjugating enzyme UbcH6 involved in the ubiquitination of IGPR-1. In vitro GST-pulldown and in vivo co-immunoprecipitation assays demonstrated that NEDD4 binds to IGPR-1. Over-expression of wild-type NEDD4 downregulated IGPR-1 and deletion of WW domains (1–4) of NEDD4 revoked its effects on IGPR-1. Knockdown of NEDD4 increased IGPR-1 levels in A375 melanoma cells. Deletion of 57 amino acids encompassing the polyproline rich (PPR) motifs on the C-terminus of IGPR-1 nullified its binding with NEDD4. Furthermore, we demonstrate that NEDD4 promotes K48- and K63-dependent polyubiquitination of IGPR-1. The NEDD4-mediated polyubiquitination of IGPR-1 stimulates lysosomal-dependent degradation of IGPR-1 as the treatment of cells with the lysosomal inhibitors, bafilomycine or ammonium chloride increased IGPR-1 levels ectopically expressed in HEK-293 cells and in multiple endogenously IGPR-1 expressing human skin melanoma cell lines.

Conclusions

NEDD4 ubiquitin E3 ligase binds to and mediates polyubiquitination of IGPR-1 leading to its lysosomal-dependent degradation. NEDD4 is a key regulator of IGPR-1 expression with implication in the therapeutic targeting of IGPR-1 in human cancers.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12929-021-00731-9.

Phage-Based Artificial Niche: The Recent Progress and Future Opportunities in Stem Cell Therapy

Self-renewal and differentiation of stem cells can be the best option for treating intractable diseases in regenerative medicine, and they occur when these cells reside in a special microenvironment, called the "stem cell niche." Thus, the niche is crucial for the effective performance of the stem cells in both in vivo and in vitro since the niche provides its functional cues by interacting with stem cells chemically, physically, or topologically. This review provides a perspective on the different types of artificial niches including engineered phage and how they could be used to recapitulate or manipulate stem cell niches. Phage-based artificial niche engineering as a promising therapeutic strategy for repair and regeneration of tissues is also discussed.

Rat Glioma Cell-Based Functional Characterization of Anti-Stress and Protein Deaggregation Activities in the Marine Carotenoids, Astaxanthin and Fucoxanthin

Stress, protein aggregation, and loss of functional properties of cells have been shown to contribute to several deleterious pathologies including cancer and neurodegeneration. The incidence of these pathologies has also been shown to increase with age and are often presented as evidence to the cumulative effect of stress and protein aggregation. Prevention or delay of onset of these diseases may prove to be unprecedentedly beneficial. In this study, we explored the anti-stress and differentiation-inducing potential of two marine bioactive carotenoids (astaxanthin and fucoxanthin) using rat glioma cells as a model. We found that the low (nontoxic) doses of both protected cells against UV-induced DNA damage, heavy metal, and heat-induced protein misfolding and aggregation of proteins. Their long-term treatment in glioma cells caused the induction of physiological differentiation into astrocytes. These phenotypes were supported by upregulation of proteins that regulate cell proliferation, DNA damage repair mechanism, and glial differentiation, suggesting their potential for prevention and treatment of stress, protein aggregation, and age-related pathologies.

Resveratrol inhibits Erk1/2-mediated adhesion of cancer cells via activating PP2A-PTEN signaling network

Resveratrol, a natural polyphenol compound, has been shown to possess anticancer activity. However, how resveratrol inhibits cancer cell adhesion has not been fully elucidated. Here, we show that resveratrol suppressed the basal or type I insulin-like growth factor (IGF)-1-stimulated adhesion of cancer cells (Rh1, Rh30, HT29, and HeLa cells) by inhibiting the extracellular signal-regulated kinase 1/2 (Erk1/2) pathway. Inhibition of Erk1/2 with U0126, knockdown of Erk1/2, or overexpression of dominant-negative mitogen-activated protein kinase kinase 1 (MKK1) strengthened resveratrol's inhibition of the basal or IGF-1-stimulated of Erk1/2 phosphorylation and cell adhesion, whereas ectopic expression of constitutively active MKK1 attenuated the inhibitory effects of resveratrol. Further research revealed that both protein phosphatase 2A (PP2A) and phosphatase and tensin homolog (PTEN)-Akt were implicated in resveratrol-inactivated Erk1/2-dependent cell adhesion. Inhibition of PP2A with okadaic acid or overexpression of dominant-negative PP2A rendered resistance to resveratrol's suppression of the basal or IGF-1-stimulated phospho-Erk1/2 and cell adhesion, whereas expression of wild-type PP2A enhanced resveratrol's inhibitory effects. Overexpression of wild-type PTEN or dominant-negative Akt or inhibition of Akt with Akt inhibitor X strengthened resveratrol's inhibition of the basal or IGF-1-stimulated Erk1/2 phosphorylation and cell adhesion. Furthermore, inhibition of mechanistic/mammalian target of rapamycin (mTOR) with rapamycin or silencing mTOR enhanced resveratrol's inhibitory effects on the basal and IGF-1-induced inhibition of PP2A-PTEN, activation of Akt-Erk1/2, and cell adhesion. The results indicate that resveratrol inhibits Erk1/2-mediated adhesion of cancer cells via activating PP2A-PTEN signaling network. Our data highlight that resveratrol has a great potential in the prevention of cancer cell adhesion.

Biochemical Characterization and Analyses of Polysialic-Acid-Associated Carrier Proteins and Genes in Piglets during Neonatal Development

Polysialic acid plays a key role in cancer metastasis and neurodevelopment. Our aim was to determine the developmental gene-expression profiles for the two polysialyltransferases ST8Sia II and ST8Sia IV, neural cell-adhesion molecules (NCAMs), SynCAM 1, neuropilin-2 (NRP2) and their polysialylated cognate glycans in different regions of the piglet brain during postnatal development. Our findings show that: 1) the cellular levels of mRNA coding for ST8Sia II and ST8Sia IV, NCAMs, SynCAM 1, NRP2 and polySia are age-dependent and cell-type-specific during neonatal brain development, 2) there was a lack of correlation between abundance level of mRNA coding for ST8Sia II and ST8Sia IV and the abundance level of the post-translation expression of polySia in all nine brain regions, 3) expression levels of polySia did not correlate with the levels of the carrier proteins NCAM-140, SynCAM 1 and NRP2 in nine brain regions, and 4) the cellular abundance of ST8Sia II and ST8Sia IV in nine subregions of piglet brain is regulated at the level of translation/post-translation, and not at the level of transcription. Collectively, our findings suggest that neuronal and glial cells within different regions of the brain have different transcriptional programs that can direct cell division at different rates based on the activity levels of ST8Sia II and ST8Sia IV and the level of their carrier proteins during neurodevelopment.

Cell Recognition Molecule L1 Regulates Cell Surface Glycosylation to Modulate Cell Survival and Migration

Background: Cell recognition molecule L1 (L1) plays an important role in cancer cell differentiation, proliferation, migration and survival, but its mechanism remains unclear. Methodology/Principal: Our previous study has demonstrated that L1 enhanced cell survival and migration in neural cells by regulating cell surface glycosylation. In the present study, we show that L1 affected cell migration and survival in CHO (Chinese hamster ovary) cell line by modulation of sialylation and fucosylation at the cell surface via the PI3K (phosphoinositide 3-kinase) and Erk (extracellularsignal-regulated kinase) signaling pathways. Flow cytometry analysis indicated that L1 modulated cell surface sialylation and fucosylation in CHO cells. Activated L1 upregulated the protein expressions of ST6Gal1 (β-galactoside α-2,6-sialyltransferase 1) and FUT9 (Fucosyltransferase 9) in CHO cells. Furthermore, activated L1 promoted CHO cells migration and survival as shown by transwell assay and MTT assay. Inhibitors of sialylation and fucosylation blocked L1-induced cell migration and survival, while decreasing FUT9 and ST6Gal1 expressions via the PI3K-dependent and Erk-dependent signaling pathways. Conclusion : L1 modulated cell migration and survival by regulation of cell surface sialylation and fucosylation via the PI3K-dependent and Erk-dependent signaling pathways.

Adhering towards tumorigenicity: altered adhesion mechanisms in glioblastoma cancer stem cells

Glioblastoma (GBM) is the most aggressive malignant primary brain tumor in adults with a high recurrence and mortality rate. GBM tumors contain a high degree of cellular heterogeneity, with cells exhibiting stem-like properties (cancer stem cells; CSCs) that are highly efficient at tumor initiation and are resistant to conventional therapies. CSCs interact with their tumor microenvironment by a large group of diverse cell adhesion molecules (CAMs) that participate in intercellular, intracellular and cell-extracellular matrix interactions. Despite the initial description of CAMs as tumor suppressors, recent work has highlighted specific CAMs that are essential for CSC maintenance and tumor progression. This review will highlight recent findings that provide support for a context-specific role of CAMs in CSC function and GBM progression.