CD44 protein, human OR C497483 Dotaz Zobrazit nápovědu
Hyaluronan is a polyanionic, megadalton-scale polysaccharide, which initiates cell signaling by interacting with several receptor proteins including CD44 involved in cell-cell interactions and cell adhesion. Previous studies of the CD44 hyaluronan binding domain have identified multiple widespread residues to be responsible for its recognition capacity. In contrast, the X-ray structural characterization of CD44 has revealed a single binding mode associated with interactions that involve just a fraction of these residues. In this study, we show through atomistic molecular dynamics simulations that hyaluronan can bind CD44 with three topographically different binding modes that in unison define an interaction fingerprint, thus providing a plausible explanation for the disagreement between the earlier studies. Our results confirm that the known crystallographic mode is the strongest of the three binding modes. The other two modes represent metastable configurations that are readily available in the initial stages of the binding, and they are also the most frequently observed modes in our unbiased simulations. We further discuss how CD44, fostered by the weaker binding modes, diffuses along HA when attached. This 1D diffusion combined with the constrained relative orientation of the diffusing proteins is likely to influence the aggregation kinetics of CD44. Importantly, CD44 aggregation has been suggested to be a possible mechanism in CD44-mediated signaling.
CD44 is a hyaluronan binding cell surface signal transducing receptor that influences motility, cell survival and proliferation as well as the formation of tumor microenvironment. CD44 contains two variable regions encoded by variable exons. Alternative splicing, which is often deregulated in cancer, can produce various isoforms of CD44 with properties that may have different tissue specific effects and therefore even diverse effects on cancer progression. This review summarizes and puts together all major regulators of alternative splicing of CD44 in cancer that have been documented so far and that have an experimentally proved effect on CD44 isoform switching. It is important to better understand the mechanisms of alternative splicing of CD44, where all the variability of CD44 originates, to be able to explain the isoform switching and occurrence of variant isoforms of CD44 (CD44v) in cancer.
- MeSH
- alternativní sestřih MeSH
- antigeny CD44 genetika metabolismus MeSH
- epitelo-mezenchymální tranzice MeSH
- lidé MeSH
- nádorové kmenové buňky metabolismus MeSH
- nádory metabolismus patologie MeSH
- protein - isoformy genetika metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
Bronchial asthma (BA) is chronic inflammation of the respiratory tract with a role played by a variety of cells, particularly mast cells, eosinophils (Eo), and T lymphocytes. The serum levels of Eo cationic protein (S-ECP) reflect the severity of bronchial inflammation and the level of bronchial hyperreactivity in asthma patients. One of the most important adhesion molecules is CD44. We examined S-ECP, the percentage of Eo with surface CD44 expression (EoCD44), and Eo count in the peripheral blood of newly diagnosed pediatric atopic patients with intermittent and persistent mild BA according to the Global Iniative for Asthma 2002, in a proportion of patients 3 months after initiation of montelukast therapy. Ninety-seven children with BA had their medical history taken, and S-ECP, with the percentage of EoCD44 determined by direct fluorescence from whole blood using flow cytometry with a Coulter EPICS XL cytometer, and Eo count, total serum immunoglobulin E levels (S-IgE) were determined. Therapy with montelukast (5 mg daily) was started in 23 children. Three months after the first collection, a second S-ECP level and EoCD44 count determinations were made. An inverse correlation between S-ECP and EoCD44 (-0.602; p < 0.0001) was found in the 97 children with BA. In the 23 children receiving montelukast we documented inverse correlation of fluctuation on S-ECP and EoCD44 after 3 months. These results were not significant. An inverse correlation between S-ECP and percent of EoCD44 was established in the 97 children with asthma before therapy initiation. The lower percentage of EoCD44 in peripheral blood in asthmatic children is due to Eo inflammation activity and attests to massive Eo invasion into the airways. Determination of the percentage proportion of EoCD44 is another potential indirect marker of the multiple features of Eo inflammation.
- MeSH
- acetáty aplikace a dávkování terapeutické užití MeSH
- antagonisté leukotrienů aplikace a dávkování terapeutické užití MeSH
- antigeny CD44 krev MeSH
- bronchiální astma farmakoterapie krev MeSH
- chinoliny aplikace a dávkování terapeutické užití MeSH
- dítě MeSH
- eozinofilní kationtový protein krev MeSH
- eozinofily MeSH
- imunoglobulin E krev MeSH
- lidé MeSH
- mladiství MeSH
- následné studie MeSH
- počet leukocytů MeSH
- předškolní dítě MeSH
- rozvrh dávkování léků MeSH
- Check Tag
- dítě MeSH
- lidé MeSH
- mladiství MeSH
- mužské pohlaví MeSH
- předškolní dítě MeSH
- ženské pohlaví MeSH
The hyaluronate receptor CD44 plays role in cell adhesion and migration and is involved in tumor metastasis. The extracellular domain of CD44 comprises the hyaluronate-binding domain (HABD) and the membrane-proximal stem region; the short intracellular portion interacts with adaptor proteins and triggers signaling pathways. Binding of hyaluronate to CD44 HABD induces an allosteric conformational change, which results in CD44 shedding. A poorly characterized epitope in human CD44 HABD is recognized by the murine monoclonal antibody MEM-85, which cross-blocks hyaluronate binding to CD44 and also induces CD44 shedding. MEM-85 is of therapeutic interest, as it inhibits growth of lung cancer cells in murine models. In this work, we employed a combination of biophysical methods to determine the MEM-85 binding epitope in CD44 HABD and to provide detailed insight into the mechanism of MEM-85 action. In particular, we constructed a single-chain variable fragment (scFv) of MEM-85 as a tool for detailed characterization of the CD44 HABD-antibody complex and identified residues within CD44 HABD involved in the interaction with scFv MEM-85 by NMR spectroscopy and mutational analysis. In addition, we built a rigid body model of the CD44 HABD-scFv MEM-85 complex using a low-resolution structure obtained by small-angle X-ray scattering. The MEM-85 epitope is situated in the C-terminal part of CD44 HABD, rather than the hyaluronate-binding groove, and the binding of MEM-85 induces a structural reorganization similar to that induced by hyaluronate. Therefore, the mechanism of MEM-85 cross-blocking of hyaluronate binding is likely of an allosteric, relay-like nature.
- MeSH
- antigeny CD44 chemie MeSH
- Jurkat buňky MeSH
- kyselina hyaluronová chemie MeSH
- lidé MeSH
- mapování epitopu MeSH
- molekulární modely MeSH
- monoklonální protilátky chemie MeSH
- mutace MeSH
- nukleární magnetická rezonance biomolekulární MeSH
- terciární struktura proteinů MeSH
- vazebná místa MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- MeSH
- antigeny CD44 analýza fyziologie MeSH
- finanční podpora výzkumu jako téma MeSH
- karcinoembryonální antigen analýza fyziologie MeSH
- lidé MeSH
- molekuly buněčné adheze nervové analýza fyziologie MeSH
- nádory plic imunologie patologie MeSH
- přežití MeSH
- prognóza MeSH
- protein - isoformy analýza fyziologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- srovnávací studie MeSH
Complex regulation of the wound healing process involves multiple interactions among stromal tissue cells, inflammatory cells, and the extracellular matrix. Low molecular weight hyaluronan (LMW HA) derived from the degradation of high molecular weight hyaluronan (HMW HA) is suggested to activate cells involved in wound healing through interaction with HA receptors. In particular, receptor CD44 is suggested to mediate cell response to HA of different MW, being the main cell surface HA receptor in stromal tissue and immune cells. However, the response of dermal fibroblasts, the key players in granulation tissue formation within the wound healing process, to LMW HA and their importance for the activation of immune cells is unclear. In this study we show that LMW HA (4.3kDa) induced pro-inflammatory cytokine IL-6 and chemokines IL-8, CXCL1, CXCL2, CXCL6 and CCL8 gene expression in normal human dermal fibroblasts (NHDF) that was further confirmed by increased levels of IL-6 and IL-8 in cell culture supernatants. Conversely, NHDF treated by HMW HA revealed a tendency to decrease the gene expression of these cytokine and chemokines when compared to untreated control. The blockage of CD44 expression by siRNA resulted in the attenuation of IL-6 and chemokines expression in LMW HA treated NHDF suggesting the involvement of CD44 in LMW HA mediated NHDF activation. The importance of pro-inflammatory mediators produced by LMW HA triggered NHDF was evaluated by significant activation of blood leukocytes exhibited as increased production of IL-6 and TNF-α. Conclusively, we demonstrated a pro-inflammatory response of dermal fibroblasts to LMW HA that was transferred to leukocytes indicating the significance of LMW HA in the inflammatory process development during the wound healing process.
- MeSH
- antigeny CD44 metabolismus MeSH
- chemokiny biosyntéza genetika MeSH
- fibroblasty účinky léků imunologie MeSH
- interleukin-6 biosyntéza genetika metabolismus MeSH
- interleukin-8 biosyntéza MeSH
- kyselina hyaluronová farmakologie MeSH
- leukocyty účinky léků metabolismus MeSH
- lidé MeSH
- malá interferující RNA metabolismus MeSH
- mediátory zánětu metabolismus MeSH
- messenger RNA genetika metabolismus MeSH
- molekulová hmotnost MeSH
- přirozená imunita účinky léků genetika MeSH
- signální transdukce účinky léků genetika MeSH
- škára cytologie MeSH
- TNF-alfa biosyntéza MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Pro- and anti-inflammatory cytokines may influence proliferation, migration, invasion, and other cellular events of prostate cancer (PCa) cells. The hyaluronan receptor CD44, which is regulated by Interleukin (IL)-4, is a prostate basal cell marker. CD44high /CD49bhigh expressing cells have been demonstrated to have tumor-initiating characteristics. Here, we aimed to analyze the effects of long-term IL-4 treatment on CD44/CD49b expression, migration, proliferation, and clonogenic potential of basal-like PCa cells. To this end PC3 cells were treated over 30 passages with 5 ng/mL IL-4 (PC3-IL4) resulting in an increased population of CD44high expressing cells. This was concurrent with a clonal outgrowth of cuboid-shaped cells, with increased size and light absorbance properties. Flow cytometry revealed that the PC3-IL4 CD44high expressing subpopulation corresponds to the CD49bhigh population. Isolation of the PC3-IL4 CD44high /CD49bhigh subpopulation via fluorescence-associated cell sorting showed increased migrative, proliferative, and clonogenic potential compared to the CD44low /CD49blow subpopulation. In conclusion, IL-4 increases a PC3 subpopulation with tumor-initiating characteristics. Thus, IL-4, similar to other cytokines may be a regulator of tumor-initiation and hence, may present a suitable therapy target in combination with current treatment options.
- MeSH
- antigeny CD44 biosyntéza MeSH
- buňky PC-3 MeSH
- integrin alfa2 biosyntéza MeSH
- interleukin-4 metabolismus MeSH
- lidé MeSH
- nádorová transformace buněk metabolismus patologie MeSH
- nádorové proteiny metabolismus MeSH
- nádory prostaty metabolismus patologie MeSH
- Check Tag
- lidé MeSH
- mužské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
This work aimed to provide, in one isolation and separation step, an overview of the content of proteins with different solubility after treatment with all-trans retinoic acid, which is considered to be an important therapeutic agent, predominantly in acute promyelocytic leukemia. Breast, ovarian, bladder, and skin cancers have been demonstrated to be suppressed by retinoic acid, as well. The bottom-up proteomic strategies were applied for the analysis of proteins extracted from triple-negative breast cancer MDA-MB-231 cells utilizing a commercially manufactured kit. The gel electrophoresis followed by MALDI-TOF MS analysis was used for protein determination. By employing PDQuest™ software, we identified several proteins affected by all-trans retinoic acid. Two proteins, vimentin and CD44, which are associated with the epithelial-mesenchymal transition, were selected for a detailed study. We have found that all-trans retinoic acid results in significantly reduced levels of vimentin and CD44 in both the cytoplasmic and membrane fractions. A significant effect was particularly evident in CD44, where protein level in the cytoplasmic fraction was almost completely suppressed.
