Pannexin 2 is expressed in murine skin and promotes UVB-induced apoptosis of keratinocytes

Pannexins (PANX) are a family of three channel-forming membrane glycoproteins expressed in the skin. Previous studies have focused on the role of PANX1 and PANX3 in the regulation of cellular functions in skin cells while PANX2, the largest member of this protein family, has not been investigated. In the current study, we explored the temporal PANX2 expression in murine skin and found that one Panx2 splice variant ( Panx2-202) tends to be more abundant at the protein level and is continuously expressed in developed skin. PANX2 was detected in the suprabasal layers of the mouse epidermis and upregulated in an in vitro model of rat epidermal keratinocyte differentiation. Furthermore, we showed that in apoptotic rat keratinocytes, upon UVB-induced caspase-3/7 activation, ectopically overexpressed PANX2 is cleaved in its C-terminal domain at D416 residue without increasing the apoptotic rate measured by caspase-3/7 activation. Notably, CRISPR-Cas9-mediated genetic deletion of rat Panx2 delays but does not impair caspase-3/7 activation and cytotoxicity in UVB-irradiated keratinocytes. We propose that endogenous PANX2 expression in keratinocytes promotes cell death after UVB insult and may contribute to skin homeostasis.

Hydrophilic magnetic covalent triazine frameworks fishing for differential N-glycopeptides in breast cancer plasma membrane

The alterations in plasma membrane glycoproteins (PMGs) have been identified as the hallmarks of cancer. The comparison and identification of differential PMGs is significant for finding new markers and understanding...

Expression and Impact of C1GalT1 in Cancer Development and Progression

C1GalT1 (T-synthase) is one of the key glycosyltransferases in the biosynthesis of O-linked mucin-type glycans of glycoproteins. It controls the formation of Core-1 disaccharide Galβ1,3GalNAcα- (Thomsen–Friedenreich oncofetal antigen, T or TF antigen) and Core-1-associated carbohydrate structures. Recent studies have shown that C1GalT1 is overexpressed in many cancers of epithelial origin including colon, breast, gastric, head and neck, pancreatic, esophageal, prostate, and hepatocellular cancer. Overexpression of C1GalT1 is often seen to also be associated with poorer prognosis and poorer patient survival. Change of C1GalT1 expression causes glycosylation changes of many cell membrane glycoproteins including mucin proteins, growth factor receptors, adhesion molecules, and death receptors. This leads to alteration of the interactions of these cell surface molecules with their binding ligands, resulting in changes of cancer cell activity and behaviors. This review summarizes our current understanding of the expression of C1GalT1 in various cancers and discusses the impact of C1GalT change on cancer cell activities in cancer development and progression.

Construction of lidocaine transmembrane nano-liposomes and preliminary study on its surface anesthetic effect

Lidocaine (Lido) is an amide local anesthetic that has both excitatory and inhibitory effects on the central nervous system, and is one of a group of commonly used local nerve block drugs that are used in the clinic. However, traditional Lido does not meet the transdermal performance requirements of surface anesthetic agents for treating pain in patients. Optimizing the preparation of a Lido transdermal preparation and improving the control of anesthetic depth and efficiency has become a challenge in the field of topical anesthesia. In this study, a new type of Lido nano-transdermal preparation, carboxymethyl chitosan-modified lidocaine liposomes (Lido-CMCSNLP), were constructed based on nano-liposomes. Carboxymethyl chitosan can enhance the permeability of hydrophilic macromolecular pathways by interacting with negatively charged membrane glycoproteins, which is beneficial for the transdermal absorption of Lido. Therefore, Lido-CMCS-NLP provides a new approach for research in clinical topical anesthesia and perioperative topical analgesics.

Bleeding in Patients with Antiphospholipid Antibodies

The antiphospholipid antibodies (aPL) are commonly associated with thrombotic events and obstetric complications. However, apart from the bleeding complications of antithrombotic therapy, the acquired coagulopathy caused by the aPL, particularly by lupus anticoagulant and anticardiolipin antibodies, might be occasionally manifested as a hemorrhagic syndrome with various clinical severity. Bleeding symptoms vary from mild (mucocutaneous) up to life-threatening (gastrointestinal, intracranial). The bleeding may be the first manifestation of aPL or appear concomitantly with thrombosis. The underlying hemostatic changes include thrombocytopenia, platelet function disorders, and coagulation factor inhibitors or deficiencies, namely prothrombin, FVII, FVIII, FX, and FXI. Thrombocytopenia is the most common finding, seen in up to 53% of patients with aPL, although it is usually mild to moderate and associated with significant bleeding only in a minority of cases. Of interest, patients with severe thrombocytopenia appear to be less likely to suffer from thrombotic events. The involved pathophysiological mechanisms are heterogeneous. Non-neutralizing antibodies against coagulation factors resulting in increased clearance, specific antibodies against platelet membrane glycoproteins, increasing platelet activation and aggregation with subsequent consumption, and immune-mediated platelet clearance are among those identified. Immunosuppression, preferably with corticosteroids, represents the first-choice therapeutic approach. Plasmapheresis is efficient in the case of catastrophic antiphospholipid syndrome. Antithrombotic therapy can be challenging, but its administration should continue as much as possible.

Physical tuning of galectin-3 signaling

Galectin-3 (Gal3) exhibits dynamic oligomerization and promiscuous binding, which can lead to concomitant activation of synergistic, antagonistic, or noncooperative signaling pathways that alter cell behavior. Conferring signaling pathway selectivity through mutations in the Gal3–glycan binding interface is challenged by the abundance of common carbohydrate types found on many membrane glycoproteins. Here, employing alpha-helical coiled-coils as scaffolds to create synthetic Gal3 constructs with defined valency, we demonstrate that oligomerization can physically regulate extracellular signaling activity of Gal3. Constructs with 2 to 6 Gal3 subunits (“Dimer,” “Trimer,” “Tetramer,” “Pentamer,” “Hexamer”) demonstrated glycan-binding properties and cell death–inducing potency that scaled with valency. Dimer was the minimum functional valency. Unlike wild-type Gal3, which signals apoptosis and mediates agglutination, synthetic Gal3 constructs induced cell death without agglutination. In the presence of CD45, Hexamer was distributed on the cell membrane, whereas it clustered in absence of CD45 via membrane glycans other than those found on CD7. Wild-type Gal3, Pentamer, and Hexamer required CD45 and CD7 to signal apoptosis, and the involvement of caspases in apoptogenic signaling was increased in absence of CD45. However, wild-type Gal3 depended on caspases to signal apoptosis to a greater extent than Hexamer, which had greater caspase dependence than Pentamer. Diminished caspase activation downstream of Hexamer signaling led to decreased pannexin-1 hemichannel opening and interleukin-2 secretion, events facilitated by the increased caspase activation downstream of wild-type Gal3 signaling. Thus, synthetic fixation of Gal3 multivalency can impart physical control of its outside-in signaling activity by governing membrane glycoprotein engagement and, in turn, intracellular pathway activation.

The Immunomodulatory CEA Cell Adhesion Molecule 6 (CEACAM6/CD66c) Is a Protein Receptor for the Influenza A Virus

To establish a productive infection in host cells, viruses often use one or multiple host membrane glycoproteins as their receptors. For Influenza A virus (IAV) such a glycoprotein receptor has not been described, to date. Here we show that IAV is using the host membrane glycoprotein CD66c as a receptor for entry into human epithelial lung cells. Neuraminidase (NA), a viral spike protein, binds to CD66c on the cell surface during IAV entry into the host cells. Lung cells overexpressing CD66c showed an increase in virus binding and subsequent entry into the cell. Upon comparison, CD66c demonstrated higher binding capacity than other membrane glycoproteins (EGFR and DC-SIGN) reported earlier to facilitate IAV entry into host cells. siRNA mediated knockdown of CD66c from lung cells inhibited virus binding on cell surface and entry into cells. Blocking CD66c by antibody on the cell surface resulted in decreased virus entry. We found that CD66c is a specific glycoprotein receptor for influenza A virus that did not affect entry of non-IAV RNA virus (Hepatitis C virus). Finally, IAV pre-incubated with recombinant CD66c protein when administered intranasally in mice showed decreased cytopathic effects in mice lungs. This publication is the first to report CD66c (Carcinoembryonic cell adhesion molecule 6 or CEACAM6) as a glycoprotein receptor for Influenza A virus.

Rosa canina L. Can Restore Endoplasmic Reticulum Alterations, Protein Trafficking and Membrane Integrity in a Dextran Sulfate Sodium-Induced Inflammatory Bowel Disease Phenotype

Rosa canina L. is a natural polyphenol-rich medicinal plant that exhibits antioxidant and anti-inflammatory activities. Recent in vivo studies have demonstrated that a methanol extract of Rosa canina L. (RCME) has reversed an inflammatory bowel disease (IBD)-like phenotype that has been triggered by dextran sulfate sodium (DSS) in mice. In the current study, we investigated the effects of RCME on perturbations of cellular mechanisms induced by DSS-treatment of intestinal Caco-2 cells, including stress response in the endoplasmic reticulum (ER), protein trafficking and sorting as well as lipid rafts integrity and functional capacities of an intestinal enzyme. 6 days post-confluent cells were treated for 24 h with DSS (3%) or simultaneously with DSS (3%) and RCME (100 µg/mL) or exclusively with RCME (100 µg/mL) or not treated. The results obtained demonstrate the ability of RCME to counteract the substantial increase in the expression levels of several ER stress markers in DSS-treated cells. Concomitantly, the delayed trafficking of intestinal membrane glycoproteins sucrase-isomaltase (SI) and dipeptidyl peptidase 4 (DPP4) induced by DSS between the ER and the Golgi has been compromised by RCME. Furthermore, RCME restored the partially impaired polarized sorting of SI and DPP4 to the brush border membrane. An efficient sorting mechanism of SI and DPP4 is tightly associated with intact lipid rafts structures in the trans-Golgi network (TGN), which have been distorted by DSS and normalized by RCME. Finally, the enzymatic activities of SI are enhanced in the presence of RCME. Altogether, DSS treatment has triggered ER stress, impaired trafficking and function of membrane glycoproteins and distorted lipid rafts, all of which can be compromised by RCME. These findings indicate that the antioxidants in RCME act at two major sites in Caco-2 cells, the ER and the TGN and are thus capable of maintaining the membrane integrity by correcting the sorting of membrane-associated proteins.

Ca2+ elevations disrupt interactions between intraflagellar transport and the flagella membrane in Chlamydomonas

ABSTRACTThe movement of ciliary membrane proteins is directed by transient interactions with intraflagellar transport (IFT) trains. The green alga Chlamydomonas has adapted this process for gliding motility, using retrograde IFT motors to move adhesive glycoproteins in the flagella membrane. Ca2+ signalling contributes directly to the gliding process, although uncertainty remains over the mechanism through which it acts. Here, we show that flagella Ca2+ elevations initiate the movement of paused retrograde IFT trains, which accumulate at the distal end of adherent flagella, but do not influence other IFT processes. On highly adherent surfaces, flagella exhibit high-frequency Ca2+ elevations that prevent the accumulation of paused retrograde IFT trains. Flagella Ca2+ elevations disrupt the IFT-dependent movement of microspheres along the flagella membrane, suggesting that Ca2+ acts by directly disrupting an interaction between retrograde IFT trains and flagella membrane glycoproteins. By regulating the extent to which glycoproteins on the flagella surface interact with IFT motor proteins on the axoneme, this signalling mechanism allows precise control of traction force and gliding motility in adherent flagella.