Forms and functions of CD44

Th2 cell clonal expansion at diagnosis in human type 1 diabetes

Soon after diagnosis with type 1 diabetes (T1D), many patients experience a period of partial remission. A longer partial remission is associated with a better response to treatment, but the mechanism is not known. The frequency of CD4+CD25+CD127hi (127-hi) cells, a cell subset with an anti-inflammatory Th2 bias, correlates positively with length of partial remission. The purpose of this study was to further characterize the nature of the Th2 bias in 127-hi cells. Single cell RNA sequencing paired with TCR sequencing of sorted 127-hi memory cells identifies clonally expanded Th2 clusters in 127-hi cells from T1D, but not from healthy donors. The Th2 clusters express GATA3, GATA3-AS1, PTGDR2, IL17RB, IL4R and IL9R. The existence of 127-hi Th2 cell clonal expansion in T1D suggests that disease factors may induce clonal expansion of 127-hi Th2 cells that prolong partial remission and delay disease progression.

Targeting CD44 Receptor Pathways in Degenerative Joint Diseases: Involvement of Proteoglycan-4 (PRG4)

Rheumatoid arthritis (RA), osteoarthritis (OA), and gout are the most prevalent degenerative joint diseases (DJDs). The pathogenesis underlying joint disease in DJDs remains unclear. Considering the severe toxicities reported with anti-inflammatory and disease-modifying agents, there is a clear need to develop new treatments that are specific in their effect while not being associated with significant toxicities. A key feature in the development of joint disease is the overexpression of adhesion molecules, e.g., CD44. Expression of CD44 and its variants in the synovial tissues of patients with DJDs is strongly associated with cartilage damage and appears to be a predicting factor of synovial inflammation in DJDs. Targeting CD44 and its downstream signaling proteins has emerged as a promising therapeutic strategy. PRG4 is a mucinous glycoprotein that binds to the CD44 receptor and is physiologically involved in joint lubrication. PRG4-CD44 is a pivotal regulator of synovial lining cell hemostasis in the joint, where lack of PRG4 expression triggers chronic inflammation and fibrosis, driven by persistent activation of synovial cells. In view of the significance of CD44 in DJD pathogenesis and the potential biological role for PRG4, this review aims to summarize the involvement of PRG4-CD44 signaling in controlling synovitis, synovial hypertrophy, and tissue fibrosis in DJDs.

Transcriptome analysis of renal ischemia/reperfusion (I/R) injury in BAFF and BAFF-R deficient mice

Acute kidney injury (AKI) accompanies with high morbidity and mortality. Incomplete renal recovery can lead to chronic and finally end-stage kidney disease, which results in the requirement of lifelong dialysis or kidney transplantation. Consequently, finding predictive biomarker and therefore developing preventive therapeutic approaches is an urgent need. For this purpose, a better understanding of the mechanism underlying AKI is necessary. The cytokine BAFF (B cell activating factor) is related to AKI by supporting B cells, which in turn play an important role in inflammatory processes and the production of antibodies. In our study, we investigated the role of BAFF and its receptor BAFF-R in the early phase of AKI. Therefore, we performed the well-established ischemia/reperfusion (I/R) model in BAFF (B6.129S2-Tnfsf13btm1Msc/J) and BAFF-R (B6(Cg)-Tnfrsf13ctm1Mass/J) deficient mice. Transcriptome of ischemic and contralateral control kidneys was analyzed and compared to wildtype littermates. We detected the upregulation of Lcn2, Lyz2, Cd44, Fn1 and Il1rn in ischemic kidneys as well as the downregulation of Kl. Furthermore, we revealed different expression patterns in BAFF and BAFF-R knockout mice. Compared to wildtype littermates, up- and downregulation of each investigated gene were higher in BAFF-R knockout and lower in BAFF knockout. Our findings indicate a positive impact of BAFF knockout in early phase of AKI, while BAFF-R knockout seems to worsen I/R injury. In addition, our study shows for the first time a remarkable renal upregulation of Lyz2 in a murine I/R model. Therefore, we consider Lyz2 as conceivable predictive or early biomarker in case of I/R and AKI.

CD44 in Bone Metastasis Development: A Key Player in the Fate Decisions of the Invading Cells?

A participant in key developmental processes, the adhesion glycoprotein CD44 is also expressed in several types of malignancies and can promote metastasis. In addition, the expression of CD44 isoforms in different types of cancer such as prostate and breast cancers may facilitate bone metastases by enhancing tumorigenicity, osteomimicry, cell migration, homing to bone, and anchorage within the bone specialized domains. Moreover, there is evidence that the CD44-ICD fragments in breast cancer cells may promote the cells' osteolytic nature. Yet the mechanisms by which CD44 and its downstream effectors promote the establishment of these cells within the bone are not fully elucidated. In this review, we summarize the current data on the roles played by CD44 in cancer progression and bone metastasis and the possible effects of its interaction with the different components of the bone marrow milieu.

Defining the Versican Interactome in Lung Health and Disease

The extracellular matrix (ECM) imparts critical mechanical and biochemical information to cells in the lungs. Proteoglycans are essential constituents of the ECM and play a crucial role in controlling numerous biological processes, including regulating cellular phenotype and function. Versican, a chondroitin sulfate proteoglycan required for embryonic development, is almost absent from mature, healthy lungs and is re-expressed and accumulates in acute and chronic lung disease. Studies using genetically engineered mice show that the versican-enriched matrix can be pro- or anti-inflammatory depending on the cellular source or disease process studied. The mechanisms whereby versican develops a contextual ECM remain largely unknown. The primary goal of this review is to provide an overview of the interaction of versican with its many binding partners, the "versican interactome," and how through these interactions, versican is an integrator of complex extracellular information. Hopefully, the information provided in this review will be used to develop future studies to determine how versican and its binding partners can develop contextual ECMs that control select biological processes. While this review focuses on versican and the lungs, what is described can be extended to other proteoglycans, tissues, and organs.

Applications of nanocomposites based on zeolitic imidazolate framework-8 in photodynamic and synergistic anti-tumor therapy

Due to the limitations resulting from hypoxia and the self-aggregation of photosensitizers, photodynamic therapy (PDT) has not been applied clinically to treat most types of solid tumors. Zeolitic imidazolate framework-8 (ZIF-8) is a common metal-organic framework that has ultra-high porosity, an adjustable structure, good biocompatibility, and pH-induced biodegradability. In this review, we summarize the applications of ZIF-8 and its derivatives in PDT. This review is divided into two parts. In the first part, we summarize progress in the application of ZIF-8 to enhance PDT and realize theranostics. We discuss the use of ZIF-8 to avoid the self-aggregation of photosensitizers, alleviate hypoxia, increase the PDT penetration depth, and combine PDT with multi-modal imaging. In the second part, we summarize how ZIF-8 can achieve synergistic PDT with other anti-tumor therapies, including chemotherapy, photothermal therapy, chemodynamic therapy, starvation therapy, protein therapy, gene therapy, and immunotherapy. Finally, we highlight the challenges that must be overcome for ZIF-8 to be widely applied in PDT. To the best of our knowledge, this is the first review of ZIF-8-based nanoplatforms for PDT.

Roles of Virion-Incorporated CD162 (PSGL-1), CD43, and CD44 in HIV-1 Infection of T Cells

Nascent HIV-1 particles incorporate the viral envelope glycoprotein and multiple host transmembrane proteins during assembly at the plasma membrane. At least some of these host transmembrane proteins on the surface of virions are reported as pro-viral factors that enhance virus attachment to target cells or facilitate trans-infection of CD4⁺ T cells via interactions with non-T cells. In addition to the pro-viral factors, anti-viral transmembrane proteins are incorporated into progeny virions. These virion-incorporated transmembrane proteins inhibit HIV-1 entry at the point of attachment and fusion. In infected polarized CD4⁺ T cells, HIV-1 Gag localizes to a rear-end protrusion known as the uropod. Regardless of cell polarization, Gag colocalizes with and promotes the virion incorporation of a subset of uropod-directed host transmembrane proteins, including CD162, CD43, and CD44. Until recently, the functions of these virion-incorporated proteins had not been clear. Here, we review the recent findings about the roles played by virion-incorporated CD162, CD43, and CD44 in HIV-1 spread to CD4⁺ T cells.

NEU4 inhibits motility of HCC cells by cleaving sialic acids on CD44

Hepatocellular carcinoma (HCC) is an extremely metastatic tumor. Sialic acids (SAs) are associated with cancer development and metastasis. NEU4 is a sialidase that removes SAs from glycoconjugates, while the function of the NEU4 in HCC has not been clearly explored. In our research, we found the NEU4 expression was significantly down-regulated in HCC tissues, which was correlated with high grades and poor outcomes of HCC. The NEU4 expression could be regulated by histone acetylation. In the functional analysis of NEU4, the cell motility was inhibited when NEU4 was overexpressed, and restored when NEU4 expression was down-regulated. Similarly, NEU4 over-expressed HCC cells showed less metastasis in athymic nude mice. Further study revealed that NEU4 could inhibit cell migration by enzymatic decomposition of SAs. Our results verified a NEU4 active site (NEU4^E235) and overexpressing inactivates NEU4^E235A that weakens the inhibition ability to cell migration. Further, 70 kinds of specific interacting proteins of NEU4 including CD44 were identified through mass spectrum. Moreover, the α2,3-linked SAs on CD44 were decreased and the hyaluronic acid (HA) binding ability was increased when NEU4 over-expressed or activated. Additionally, the mutation of CD44 with six N-glycosylation sites showed less sensibility to NEU4 on cell migration compared with wild-type CD44. In summary, our results revealed the mechanism of low expression of NEU4 in HCC and its inhibitory effect on cell migration by removal of SAs on CD44, which may provide new treatment strategies to control the motility and metastasis of HCC.

Cardiovascular Effects Mediated by HMMR and CD44

Cardiovascular disease (CVD) is the leading cause of death worldwide. The most dangerous life-threatening symptoms of CVD are myocardial infarction and stroke. The causes of CVD are not entirely clear, and new therapeutic targets are still being sought. One of the factors involved in CVD development among vascular damage and oxidative stress is chronic inflammation. It is known that hyaluronic acid plays an important role in inflammation and is regulated by numerous stimuli, including proinflammatory cytokines. The main receptors for hyaluronic acid are CD44 and RHAMM. These receptors are membrane proteins that differ in structure, but it seems that they can perform similar or synergistic functions in many diseases. Both RHAMM and CD44 are involved in cell migration and wound healing. However, their close association with CVD is not fully understood. In this review, we describe the role of both receptors in CVD.

Enhanced migration of engrafted retinal progenitor cells into the host retina via disruption of glial barriers

Purpose

Migration and integration remain critical challenges for stem cell replacement therapy. Glial barriers play an important role in preventing cell migration and integration. The purpose of this study was to investigate the effect and mechanisms of chondroitinase ABC on the migration of murine retinal progenitor cells (mRPCs) transplanted into the subretinal space of B6 mice.

Methods

mRPCs were harvested from the neural retinas of P1 enhanced green fluorescent protein (GFP) B6 mice. Two μl containing 2 × 10⁵ expanded RPCs alone or combined with chondroitinase ABC in suspension were injected into the subretinal space of the recipient B6 mice. Immunohistochemistry was performed on the recipient B6 retinas to evaluate the glial barrier formation and migration of the mRPCs. Western blotting was also used to check the expression of the glial barriers.

Results

Glial fibrillary acidic protein (GFAP) and vimentin could be seen around the transplanted mRPCs in the B6 mice. Formation of glial barriers prevented the migration of donor cells into the retinal layers. Chondroitinase ABC promoted the migration and survival rates of the engrafted retinal progenitor cells in the retinal layers of recipient B6 mice. Injection induced upregulation of GFAP, chondroitin, and CD44 expression. Chondroitinase ABC disrupted the glial barriers. The CD44 around the mRPCs was much lower in the chondroitinase group. However, the CD44 in the retinal layers was considerably higher in the chondroitinase group. With the employment of chondroitinase ABC, more cells migrated into the outer nuclear layer or inner nuclear layer. The chondroitin and CD44 expression decreased 3 weeks after transplantation in the chondroitinase ABC group.

Conclusions

Chondroitinase ABC degraded glial barriers and enhanced the migration of transplanted mouse retinal progenitor cells. Chondroitinase ABC may also have induced activation of the CD44 signaling pathway to exert the effect.

Oxidized polysaccharides for anticancer-drug delivery: What is the role of structure?

Study provides an in-depth analysis of the structure-function relationship of polysaccharide anticancer drug carriers and points out benefits and potential drawbacks of differences in polysaccharide glycosidic bonding, branching and drug binding mode of the carriers. Cellulose, dextrin, dextran and hyaluronic acid have been regioselectively oxidized to respective dicarboxylated derivatives, allowing them to directly conjugate cisplatin, while preserving their major structural features intact. The structure of source polysaccharide has crucial impact on conjugation effectiveness, carrier capacity, drug release rates, in vitro cytotoxicity and cellular uptake. For example, while branched structure of dextrin-based carrier partially counter the undesirable initial burst release, it also attenuates the cellular uptake and the cytotoxicity of carried drug. Linear polysaccharides containing β-(1→4) glycosidic bonds and oxidized at C2 and C3 (cellulose and hyaluronate) have the best overall combination of structural features for improved drug delivery applications including potentiation of the cisplatin efficacy towards malignances.

Terminal Schwann Cell Aging: Implications for Age-Associated Neuromuscular Dysfunction

Action potential is transmitted to muscle fibers through specialized synaptic interfaces called neuromuscular junctions (NMJs). These structures are capped by terminal Schwann cells (tSCs), which play essential roles during formation and maintenance of the NMJ. tSCs are implicated in the correct communication between nerves and muscles, and in reinnervation upon injury. During aging, loss of muscle mass and strength (sarcopenia and dynapenia) are due, at least in part, to the progressive loss of contacts between muscle fibers and nerves. Despite the important role of tSCs in NMJ function, very little is known on their implication in the NMJ-aging process and in age-associated denervation. This review summarizes the current knowledge about the implication of tSCs in the age-associated degeneration of NMJs. We also speculate on the possible mechanisms underlying the observed phenotypes.

CD4+CD25+CD127hi cell frequency predicts disease progression in type 1 diabetes

Transient partial remission, a period of low insulin requirement experienced by most patients soon after diagnosis, has been associated with mechanisms of immune regulation. A better understanding of such natural mechanisms of immune regulation might identify new targets for immunotherapies that reverse type 1 diabetes (T1D). In this study, using Cox model multivariate analysis, we validated our previous findings that patients with the highest frequency of CD4⁺CD25⁺CD127^hi (127-hi) cells at diagnosis experience the longest partial remission, and we showed that the 127-hi cell population is a mix of Th1- and Th2-type cells, with a significant bias toward antiinflammatory Th2-type cells. In addition, we extended these findings to show that patients with the highest frequency of 127-hi cells at diagnosis were significantly more likely to maintain β cell function. Moreover, in patients treated with alefacept in the T1DAL clinical trial, the probability of responding favorably to the antiinflammatory drug was significantly higher in those with a higher frequency of 127-hi cells at diagnosis than those with a lower 127-hi cell frequency. These data are consistent with the hypothesis that 127-hi cells maintain an antiinflammatory environment that is permissive for partial remission, β cell survival, and response to antiinflammatory immunotherapy.

CD44 variant 6 is involved in the attachment and invasion of endometrial cells to peritoneum

OBJECTIVE

To study the effects of CD44 standard (CD44s), CD44v3, and CD44v6 overexpression (OE) on immortalized human endometrial epithelial (iEECs) and stroma cells (human endometrial stromal cells [hESCs]) using in vitro assays and a nude mouse xenograft model. Menstrual endometrial cells from women with endometriosis have increased adhesion and also express higher levels of CD44 variant 6 (v6), but not v3, compared to menstrual endometrial cells from women without endometriosis.

DESIGN

In vitro studies and in vivo xenograft model.

SETTING

Academic center.

PATIENTS(S)

Deidentified immortalized endometrial epithelial tissue samples of a reproductive-age woman.

INTERVENTION(S)

Overexpression of CD44s, CD44v3, and CD44v6 was carried out using lipofectamine, and their expression was verified with mRNA and protein in iEEC and hESCs. The OE cells were used in in vitro studies and an in vivo xenograft model compared to plasmid control.

MAIN OUTCOME MEASURE(S)

The effect of CD44s, CD44v3, and CD44v6 OE on attachment and invasion assays and a xenograft model with immortalized human stromal and epithelial cells.

RESULT(S)

Expression of mRNA and protein confirmed appropriate OE of CD44s, CD44v3, and CD44v6 in the different cell types. CD44v6 OE increased attachment of hESCs compared with controls. CD44v6 OE did not change the attachment of iEECs. There was no difference in attachment in iEECs or hESCs with OE of CD44s or CD44v3.

CONCLUSION(S)

Overexpression of CD44v6 increases attachment of hESCs to peritoneal mesothelial cells in an in vitro assay and an in vivo xenograft model. Menstrual endometrial cell type and CD44 variants play a complex role in the development of the early endometriotic lesion.

Emerging roles of ECM remodeling processes in cancer

Extracellular matrix (ECM) plays a central and dynamic role in the creation of tumor microenvironment. Herein we discuss the emerging biophysical and biochemical aspects of ECM buildup and proteolysis in cancer niche formation. Dysregulated ECM remodeling by cancer cells facilitate irreversible proteolysis and crosslinking, which in turn influence cell signaling, micro environmental cues, angiogenesis and tissue biomechanics. Further, we introduce the emerging roles of cancer microbiome in aberrant tumor ECM remodeling and membrane bound nano-sized vesicles called exosomes in creation of distant pre-metastatic niches. A detailed molecular and biophysical understanding of the ECM morphologies and its components such as key enzymes, structural and signaling molecules are critical in identifying the next generation of therapeutic and diagnostic targets in cancer.

Activation and Proliferation of PD-1+ Kidney Double-Negative T Cells Is Dependent on Nonclassical MHC Proteins and IL-2

BACKGROUND

CD4^- CD8^- double-negative (DN) αβ T cells with innate-like properties represent a significant component of T cells in human and mouse kidneys. They spontaneously proliferate in the steady state and protect against ischemic AKI. However, the mechanisms regulating DN T cell homeostasis and responses to external danger signals from "sterile" inflammation remain poorly understood.

METHODS

We used knockout mice, functional assays, and an established ischemic AKI model to investigate the role of various MHC class I and II molecules in regulating kidney DN T cells. We also studied human nephrectomy samples.

RESULTS

Deficiency of β2m-dependent MHC class I (but not MHC class II) molecules led to significant reduction in frequency or absolute numbers of kidney DN T cells due to impaired activation, proliferation, increased apoptosis, and loss of an NK1.1⁺ subset of DN T cells. The remaining DN T cells in β2m knockout mice mainly comprised a programmed cell death protein-1 receptor (PD-1⁺) subset that depends on IL-2 provided by conventional T cells for optimal homeostasis. However, this PD-1⁺ subset remained highly responsive to changes in milieu, demonstrated by responses to infused lymphocytes. It was also the major responder to ischemic AKI; the NK1.1⁺ subset and CD8⁺ T cells had minimal responses. We found both DN T cell subsets in normal and cancerous human kidneys, indicating possible clinical relevance.

CONCLUSIONS

DN T cells, a unique population of kidney T cells, depend on nonclassical β2m molecules for homeostasis and use MHC-independent mechanisms to respond to external stimuli. These results have important implications for understanding the role these cells play during AKI and other immune cell-mediated kidney diseases.

Molecular weight of surface immobilized hyaluronic acid influences CD44-mediated binding of gastric cancer cells

The physiological importance of the interactions between hyaluronic acid (HA) and its main membrane receptor, CD44, in pathological processes, e.g. cancer, is well recognized. However, these interactions are mainly studied in solution, whereas HA in the extracellular matrix (ECM) is partially immobilized via its interactions with other ECM components. We therefore, developed substrates in which HA is presented in an ECM-relevant manner. We immobilized HA with different molecular weights (Mw) in a Layer-by-Layer (LbL) fashion and studied the interactions of the substrates with CD44 and two human gastric cancer cell lines that overexpress this receptor, namely AGS and MKN45. We demonstrate that MKN45 cells are more sensitive to the LbL substrates as compared with AGS. This difference is due to different CD44 expression: while CD44 is detected mainly in the cytoplasm of AGS, MKN45 express CD44 predominantly at the cell membrane where it is involved in the recognition and binding of HA. The invasiveness of the studied cell lines was also evaluated as a function of HA Mw. Invasive profile characterized by low cell adhesion, high cell motility, high expression of cortactin, formation of invadopodia and cell clusters was observed for MKN45 cells when they are in contact with substrates presenting HA of high Mw.

Overexpression of CD44 Variant 9: A Novel Cancer Stem Cell Marker in Human Cholangiocarcinoma in Relation to Inflammation

Various CD44 isoforms are expressed in several cancer stem cells during tumor progression and metastasis. In particular, CD44 variant 9 (CD44v9) is highly expressed in chronic inflammation-induced cancer. We investigated the expression of CD44v9 and assessed whether CD44v9 is a selective biomarker of human cholangiocarcinoma (CCA). The expression profile of CD44v9 was evaluated in human liver fluke Opisthorchis viverrini-related CCA (OV-CCA) tissues, human CCA (independent of OV infection, non-OV-CCA) tissues, and normal liver tissues. CD44v9 overexpression was detected by immunohistochemistry (IHC) in CCA tissues. There was a higher level of CD44v9 expression and IHC score in OV-CCA tissues than in non-OV-CCA tissues, and there was no CD44v9 staining in the bile duct cells of normal liver tissues. In addition, we observed significantly higher expression of inflammation-related markers, such as S100P and COX-2, in OV-CCA tissues compared to that in non-OV and normal liver tissues. Thus, these findings suggest that CD44v9 may be a novel candidate CCA stem cell marker and may be related to inflammation-associated cancer development.

Secondary lymphoid organ fibroblastic reticular cells mediate trans-infection of HIV-1 via CD44-hyaluronan interactions

Fibroblastic reticular cells (FRCs) are stromal cells in secondary lymphoid organs, the major sites for HIV-1 infection of CD4⁺ T cells. Although FRCs regulate T cell survival, proliferation, and migration, whether they play any role in HIV-1 spread has not been studied. Here, we show that FRCs enhance HIV-1 spread via trans-infection in which FRCs capture HIV-1 and facilitate infection of T cells that come into contact with FRCs. FRCs mediate trans-infection in both two- and three-dimensional culture systems and in a manner dependent on the virus producer cells. This producer cell dependence, which was also observed for virus spread in secondary lymphoid tissues ex vivo, is accounted for by CD44 incorporated into virus particles and hyaluronan bound to such CD44 molecules. This virus-associated hyaluronan interacts with CD44 expressed on FRCs, thereby promoting virus capture by FRCs. Overall, our results reveal a novel role for FRCs in promoting HIV-1 spread.

Fibroblastic reticular cells (FRCs) are important regulators of T cell survival, proliferation, and migration in secondary lymphoid organs, but their role in HIV infection isn’t studied. Here, Murakami et al. show that FRCs enhance HIV spread via CD44- and hyaluronan-mediated trans-infection.

Aggressive Phenotype of Cells Disseminated via Hematogenous and Lymphatic Route in Breast Cancer Patients

Intratumoral heterogeneity of breast cancer remains a major challenge in successful treatment. Failure of cancer therapies can also be accredited to inability to systemically eradicate cancer stem cells (CSCs). Recent evidence points to the role of epithelial-mesenchymal transition (EMT) in expanding the pool of tumor cells with CSCs features. Thus, we assessed expression level as well as heterogeneity of CSCs markers in primary tumors (PT), lymph node metastasis (LNM), and circulating tumor cells (CTCs)-enriched blood fractions in order to correlate them with signs of EMT activation as well as clinicopathological data of breast cancer patients. Level of CSCs markers (ALDH1, CD44, CD133, OCT-4, NANOG) and EMT markers was quantified in PT (N=107), LNM (N=56), and CTCs-enriched blood fractions (N=85). Heterogeneity of CSCs markers expression within each PT and LNM was assessed by calculating Gini Index. Percentage of ALDH1-positive cells was elevated in PT in comparison to LNM (P = .005). However, heterogeneity of the four CSCs markers: ALDH1 (P = .019), CD133 (P = .009), OCT-4 (P = .027), and CD44 (P < .001) was decreased in LNM. Samples classified as mesenchymal (post-EMT) showed elevated expression of CSCs markers (OCT-4 and CD44 in PT; OCT-4 in LNM; ALDH1, OCT-4, NANOG, CD44 in CTCs). Patients with mesenchymal-like CTCs had worse prognosis than patients with epithelial-like or no CTCs (P = .0025). CSCs markers are enriched in PT, LNM, and CTCs with mesenchymal features, but their heterogeneity is decreased in metastatic lymph nodes. Mesenchymal CTCs phenotype correlates with poor prognosis of the patients.

CD44v10: An Antimetastatic Membrane Glycoprotein for Pancreatic Cancer

Aims

The aims of this study were 1) to investigate the mRNA pattern of CD44 variants in three primary (MIA PaCa 2, PANC-1, PSN-1) and two metastatic (CAPAN-1, SUIT-2) pancreatic cancer (PC) cell lines; 2) to ascertain whether the genetic transfer of CD44s and CD44v10 modifies the adhesion of PC cells to the extracellular matrix (ECM) in vitro and their metastatic behavior in vivo.

Methods

CD44 mRNA analysis was done by means of RT-PCR. Adhesion to ECM the was assessed using coated microtiter plates. For the study of CD44v10 insertion in the CAPAN-1 line, liposome-mediated DNA transfer was used. SCID mice were employed for in vivo experiments.

Results

CD44v10 mRNA was not expressed by the CAPAN-1 nor by four of the six SUIT-2-derived clones. The stable expression of CD44v10 by modified CAPAN-1 significantly enhanced fibronectin adhesion. Mice without either liver or pancreatic metastases were more frequently found among the animals injected with modified (CD44v10 expressing) than with non-modified CAPAN-1.

Conclusions

1) It is possible to differentiate between metastatic and non-metastatic PC cells on the basis of CD44v10 expression; 2) CD44v10 seems to be involved in mediating fibronectin adhesion in vitro and in counteracting metastases in vivo.

Human CD4+ CD25+ CD127hi cells and the Th1/Th2 phenotype

CD4⁺ T cells that co-express CD25 and CD127 (CD25⁺CD127⁺) make up around 20% of all circulating CD4⁺ memory T cells in healthy people. The clinical significance of these cells is that in children with type 1 diabetes their relative frequency at diagnosis is significantly and directly correlated with rate of disease progression. The purpose of this study was to further characterize the CD25⁺CD127^hi cells. We show that they are a mix of Th1 and Th2 cells however, they have a significantly higher relative frequency of pre-committed and committed Th2 cells, and secrete significantly higher levels of Th2-type cytokines than CD25^- memory T cells. Further, these cells are neither exhausted nor senescent and proliferate to the same extent as CD25^- memory cells. Thus, CD25⁺CD127^hi cells are a highly active subset of memory T cells that might play a role in controlling inflammation via anti-inflammatory Th2-type deviation.

Dually modified transmembrane proteoglycans in development and disease

Aberrant cell signaling in response to secreted growth factors has been linked to the development of multiple diseases, including cancer. As such, understanding mechanisms that control growth factor availability and receptor-growth factor interaction is vital. Dually modified transmembrane proteoglycans (DMTPs), which are classified as cell surface macromolecules composed of a core protein decorated with covalently linked heparan sulfated (HS) and/or chondroitin sulfated (CS) glycosaminoglycan (GAG) chains, provide one type of regulatory mechanism. Specifically, DMTPs betaglycan and syndecan-1 (SDC1) play crucial roles in modulating key cell signaling pathways, such as Wnt, transforming growth factor-β and fibroblast growth factor signaling, to affect epithelial cell biology and cancer progression. This review outlines current and potential functions for betaglycan and SDC1, with an emphasis on comparing individual roles for HS and CS modified DMTPs. We highlight the mutual dependence of DMTPs' GAG chains and core proteins and provide comprehensive knowledge on how these DMTPs, through regulation of ligand availability and receptor internalization, control cell signaling pathways involved in development and disease.

Myosin 1g Contributes to CD44 Adhesion Protein and Lipid Rafts Recycling and Controls CD44 Capping and Cell Migration in B Lymphocytes

Cell migration and adhesion are critical for immune system function and involve many proteins, which must be continuously transported and recycled in the cell. Recycling of adhesion molecules requires the participation of several proteins, including actin, tubulin, and GTPases, and of membrane components such as sphingolipids and cholesterol. However, roles of actin motor proteins in adhesion molecule recycling are poorly understood. In this study, we identified myosin 1g as one of the important motor proteins that drives recycling of the adhesion protein CD44 in B lymphocytes. We demonstrate that the lack of Myo1g decreases the cell-surface levels of CD44 and of the lipid raft surrogate GM1. In cells depleted of Myo1g, the recycling of CD44 was delayed, the delay seems to be caused at the level of formation of recycling complex and entry into recycling endosomes. Moreover, a defective lipid raft recycling in Myo1g-deficient cells had an impact both on the capping of CD44 and on cell migration. Both processes required the transportation of lipid rafts to the cell surface to deliver signaling components. Furthermore, the extramembrane was essential for cell expansion and remodeling of the plasma membrane topology. Therefore, Myo1g is important during the recycling of lipid rafts to the membrane and to the accompanied proteins that regulate plasma membrane plasticity. Thus, Myosin 1g contributes to cell adhesion and cell migration through CD44 recycling in B lymphocytes.

Memory T Cells in Type 1 Diabetes: the Devil is in the Detail

PURPOSE OF REVIEW

Therapies that target beta-cell antigen-specific T cells subsets have not been as successful in patients with type 1 diabetes as in mice. This might be explained by complexities in the repertoire of beta-cell antigen-specific T cells and the variety of T cell subsets involved in type 1 diabetes development in human.

RECENT FINDINGS

T cells that infiltrate islets of people with type 1 diabetes (i) react towards known islet cell antigens but also unknown antigens, (ii) differ from one patient to another, and (iii) are also present in the circulation, but not in the islets, of healthy people. Moreover, several circulating memory T cell subsets not recognized as relevant in mouse are significantly associated with clinical outcome. A more detailed understanding of the specificity, phenotype, and function of T cells that are associated with defined clinical outcomes might identify new pathways for therapeutic intervention.

Diverse properties of the mesothelial cells in health and disease

Mesothelial cells (MCs) form the superficial anatomic layer of serosal membranes, including pleura, pericardium, peritoneum, and the tunica of the reproductive organs. MCs produce a protective, non-adhesive barrier against physical and biochemical damages. MCs express a wide range of phenotypic markers, including vimentin and cytokeratins. MCs play key roles in fluid transport and inflammation, as reflected by the modulation of biochemical markers such as transporters, adhesion molecules, cytokines, growth factors, reactive oxygen species and their scavengers. MCs synthesize extracellular matrix related molecules, and the surface of MC microvilli secretes a highly hydrophilic protective barrier, "glycocalyx", consisting mainly of glycosaminoglycans. MCs maintain a balance between procoagulant and fibrinolytic activation by producing a whole range of regulators, can synthetize fibrin and therefore form adhesions. Synthesis and recognition of hyaluronan and sialic acids might be a new insight to explain immunoactive and immunoregulatory properties of MCs. Epithelial to mesenchymal transition of MCs may involve serosal repair and remodeling. MCs might also play a role in the development and remodeling of visceral adipose tissue. Taken together, MCs play important roles in health and disease in serosal cavities of the body. The mesothelium is not just a membrane and should be considered as an organ.

The Cell Surface Receptor CD44: NMR-Based Characterization of Putative Ligands

The cell surface receptor CD44 is a glycoprotein belonging to the hyaluronan-binding proteins, termed hyaladherins. CD44 is expressed in a wide variety of isoforms in many cells and, in particular, is present on the surface of malignant cells where it is involved in the onset and progression of cancer. In a first attempt to identify novel CD44-binding agents, we first characterized, with NMR spectroscopic techniques, several agents that were reported to bind to human CD44 (hCD44). To our surprise, however, none of these putative CD44-binding agents, including a peptide that is in phase 2 clinical trials (A6 peptide) and a recently reported fragment hit, were found to interact significantly with recombinant hCD44(21-178). Nonetheless, we further report that a fragment-screening campaign, with solution NMR spectroscopy as the detection method, identified a viable fragment hit that bound in a potentially functional pocket on the surface of CD44, opposite to the hyaluronic acid binding site. We hypothesize that this pocket could be indirectly associated with the cellular and in vivo activity of the A6 peptide, which would provide a novel framework for the possible development of therapeutically viable CD44 antagonists.

A pilot study showing associations between frequency of CD4(+) memory cell subsets at diagnosis and duration of partial remission in type 1 diabetes

In some patients with type 1 diabetes the dose of insulin required to achieve euglycemia is substantially reduced soon after diagnosis. This partial remission is associated with β-cell function and good glucose control. The purpose of this study was to assess whether frequencies of CD4(+) T cell subsets in children newly diagnosed with type 1 diabetes are associated with length of partial remission. We found that the frequency of CD4(+) memory cells, activated Treg cells and CD25(+) cells that express a high density of the IL-7 receptor, CD127 (CD127(hi)) are strongly associated with length of partial remission. Prediction of length of remission via Cox regression is significantly enhanced when CD25(+) CD127(hi) cell frequency is combined with either Insulin Dependent Adjusted A1c (IDAA1c), or glycosylated hemoglobin (HbA1c), or C-peptide levels at diagnosis. CD25(+) CD127(hi) cells do not express Foxp3, LAG-3 and CD49b, indicating that they are neither Treg nor Tr1 cells.

Impaired Development of Early Endometriotic Lesions in CD44 Knockout Mice

Previous studies have shown endometrial cell (EC) CD44 and peritoneal mesothelial cell (PMC)-associated hyaluronan (hyaluronic acid [HA]) are involved in the attachment of endometrial stroma and epithelial cells to peritoneal mesothelium. Here we assess the CD44-HA interaction in the formation of the early endometriotic lesion using CD44(-/-) (knockout) mice. Using an established murine model and crossover technique, endometrial tissue from donor mice (wild type [WT] and CD44(-/-)) was used to induce endometriosis in recipient mice (WT and CD44(-/-)). Endometriotic lesions were visualized by fluorescent microscopy and confirmed by hematoxylin and eosin staining. Early endometriotic lesions were decreased when CD44(-/-) endometrium was placed in WT recipients and when WT endometrium was placed in CD44(-/-) recipients (P = .002). Early endometriotic lesions were also significantly decreased when both peritoneal and endometrial tissues lacked CD44 expression (P < .01). These studies demonstrate that both EC and PMC CD44 play a role in the development of early endometriotic lesion.

Epithelial adhesion molecules and the regulation of intestinal homeostasis during neutrophil transepithelial migration

Epithelial adhesion molecules play essential roles in regulating cellular function and maintaining mucosal tissue homeostasis. Some form epithelial junctional complexes to provide structural support for epithelial monolayers and act as a selectively permeable barrier separating luminal contents from the surrounding tissue. Others serve as docking structures for invading viruses and bacteria, while also regulating the immune response. They can either obstruct or serve as footholds for the immune cells recruited to mucosal surfaces. Currently, it is well appreciated that adhesion molecules collectively serve as environmental cue sensors and trigger signaling events to regulate epithelial function through their association with the cell cytoskeleton and various intracellular adapter proteins. Immune cells, particularly neutrophils (PMN) during transepithelial migration (TEM), can modulate adhesion molecule expression, conformation, and distribution, significantly impacting epithelial function and tissue homeostasis. This review discusses the roles of key intestinal epithelial adhesion molecules in regulating PMN trafficking and outlines the potential consequences on epithelial function.

Modulation of CD44 Activity by A6-Peptide

Hyaluronan (HA) is a non-sulfated glycosaminoglycan distributed throughout the extracellular matrix that plays a major role in cell adhesion, migration, and proliferation. CD44, a multifunctional cell surface glycoprotein, is a receptor for HA. In addition, CD44 is known to interact with other receptors and ligands, and to mediate a number of cellular functions as well as disease progression. Studies have shown that binding of HA to CD44 in cancer cells activates survival pathways resulting in cancer cell survival. This effect can be blocked by anti-CD44 monoclonal antibodies. A6 is a capped, eight l-amino acid peptide (Ac-KPSSPPEE-NH2) derived from the biologically active connecting peptide domain of the serine protease, human urokinase plasminogen activator (uPA). A6 neither binds to the uPA receptor (uPAR) nor interferes with uPA/uPAR binding. A6 binds to CD44 resulting in the inhibition of migration, invasion, and metastasis of tumor cells, and the modulation of CD44-mediated cell signaling. A6 has been shown to have no dose-limiting toxicity in animal studies. A6 has demonstrated efficacy and an excellent safety profile in Phase 1a, 1b, and 2 clinical trials. In animal models, A6 has also exhibited promising results for the treatment of diabetic retinopathy and wet age-related macular degeneration through the reduction of retinal vascular permeability and inhibition of choroidal neovascularization, respectively. Recently, A6 has been shown to be directly cytotoxic for B-lymphocytes obtained from patients with chronic lymphocytic leukemia expressing the kinase, ZAP-70. This review will discuss the activity of A6, A6 modulation of HA and CD44, and a novel strategy for therapeutic intervention in disease.

Expression profile of standard and variants forms of CD44 related to prostate cancer behavior

CD44 is a transmembrane glycoprotein and is regarded as a potential marker in various tumors. The aim of our study was to analyze the expression of the standard form of CD44 (CD44s) and its isoforms in localized prostate cancer (PCa), and to correlate these data with the classical prognostic factors and biochemical recurrence.Ninety-four surgical specimens were analyzed in this study. The expression levels of CD44s and all its 9 variants were analyzed by quantitative real time PCR (qRT-PCR). The control group consisted of 14 specimens from patients with benign prostatic hyperplasia. We correlated all the expression profiles with biochemical recurrence, as defined by a PSA >0.4 ng/mL in a mean follow-up period of 53.3 months. In PCa, CD44s was underexpressed and all the other isoforms were overexpressed. The mean expression level of most variants was higher in patients who had not recurred, and a higher expression of CD44v2 independently correlated with a better recurrence-free survival rate (p=0.045). This variant was also underexpressed in metastatic PCa cell lines. There was no correlation between the expression levels of any of the CD44 isoforms and the classical prognostic factors.We here demonstrated that PCa cases are characterized by a change in the expression of CD44, with a loss of CD44s and an overexpression of all the other CD44 variants. However, during cancer progression we found a loss of expression of all CD44 variants, and a correlation between higher expression of CD44v2 and a better recurrence-free survival rate. The understanding of the CD44 expression patterns in PCa could contribute to its use as a new prognostic marker.

Tackling the cancer stem cells - what challenges do they pose?

Since their identification in 1994, cancer stem cells (CSCs) have been objects of intensive study. Their properties and mechanisms of formation have become a major focus of current cancer research, in part because of their enhanced ability to initiate and drive tumour growth and their intrinsic resistance to conventional therapeutics. The discovery that activation of the epithelial-to-mesenchymal transition (EMT) programme in carcinoma cells can give rise to cells with stem-like properties has provided one possible mechanism explaining how CSCs arise and presents a possible avenue for their therapeutic manipulation. Here we address recent developments in CSC research, focusing on carcinomas that are able to undergo EMT. We discuss the signalling pathways that create these cells, cell-intrinsic mechanisms that could be exploited for selective elimination or induction of their differentiation, and the role of the tumour microenvironment in sustaining them. Finally, we propose ways to use our current knowledge of the complex biology of CSCs to design novel therapies to eliminate them.

Effect of hyaluronan on developmental competence and quality of oocytes and obtained blastocysts from in vitro maturation of bovine oocytes

The objective of the present study was to evaluate the effect of hyaluronan (HA) during IVM on meiotic maturation, embryonic development, and the quality of oocytes, granulosa cells (GC), and obtained blastocysts. COCs were matured in vitro in control medium and medium with additional 0.035% or 0.07% of exogenous HA. The meiotic maturity did not differ between the analysed groups. The best rate and the highest quality of obtained blastocysts were observed when 0.07% HA was used. A highly significant difference (P < 0.001) was noted in the mean number of apoptotic nuclei per blastocyst and in the DCI between the 0.07% HA and the control blastocysts (P < 0.01). Our results suggest that addition of 0.035% HA and 0.07% HA to oocyte maturation media does not affect oocyte nuclear maturation and DNA fragmentation. However, the addition of 0.07% HA during IVM decreases the level of blastocysts DNA fragmentation. Finally, our results suggest that it may be risky to increase the HA concentration during IVM above 0.07% as we found significantly higher Bax mRNA expression levels in GC cultured with 0.07% HA. The final concentration of HA being supplemented to oocyte maturation media is critical for the success of the IVP procedure.

Cancer Stem Cell Markers CD44, CD133 in Primary Gastric Adenocarcinoma

Cancer stem cells (CSCs) are unique subpopulations that have the capacity to drive malignant progression with renewal abilities. Recently the role of some of CSCs in gastric adenocarcinoma has been studied. This study was performed in order to evaluate CD44 and CD133 expressions by immunohistochemistry in 95 primary gastric adenocarcinoma and their relation to clinical and pathological parameters of these tumors. There was a significant correlation between CD44 expression and cancer subtype (intestinal), tumor size (4-8 cm), depth of invasion, no lymphatic/vascular invasion and moderate differentiation. There was a significant correlation between CD133 expression and patient's age (> 65 years), cancer subtype (intestinal), tumor size (4-8 cm), depth of invasion and moderate differentiation. CSC markers like CD 44 and CD133 had high expression in primary gastric adenocarcinoma and had some relations to clinical and pathological parameters of tumors.

Evaluation of a triple combination of cytokeratin 20, p53 and CD44 for improving detection of urothelial carcinoma in urine cytology specimens

Background:

Atypical urine cytology results trigger cystoscopy or molecular tests, both of which are costly, complex and difficult to perform tests. Several immunostains are being investigated to improve cancer detection; however, cytology material is limited and restricts the use of multiple immunostains. This study was designed to determine the utility of a cocktail of three stains, cytokeratin (CK20), p53 and CD44 in urine cytology samples for improving the detection of urothelial carcinoma.

Materials and Methods:

Urine cytology specimens with cell blocks containing adequate cytologic material between 2005 and 2010 and subsequent follow-up biopsy and/or Urovysion test (102 cases including 29 negative, 56 atypical and 17 malignant) were included in the study and evaluated with the triple stain. Results were first validated on the positive and negative cases and then applied to the atypical cases to determine the utility in the diagnosis of urothelial carcinoma.

Results:

Based on the validation and published literature, two distinct immunoprofiles were defined – malignant, characterized by at least five CK20 and/or p53 positive atypical cells and reactive, all other staining patterns. The malignant immunoprofile showed 88% sensitivity, 78% specificity, 74% positive predictive value (PPV) and 90% negative predictive value (NPV) for detecting urothelial carcinoma. These values improved to 95% sensitivity and 96% NPV when low-grade urothelial carcinoma cases were excluded.

Summary:

Our results indicate that the triple stain is an inexpensive, easy to perform test most useful for differentiating high-grade urothelial carcinoma from its mimics. However Inclusion of CD44 in the cocktail did not provide additional value and is best excluded.

CD44 regulates vascular endothelial barrier integrity via a PECAM-1 dependent mechanism

Vascular integrity is a critical parameter in normal growth and development. Loss of appropriate vascular barrier function is present in various immune- and injury-mediated pathological conditions. CD44 is an adhesion molecule expressed by multiple cell types, including endothelial cells (EC). The goal of the present study was to examine how loss of CD44 affected vascular permeability. Using C57BL/6 WT and CD44-KO mice, we found no significant permeability to Evan's Blue in either strain at baseline. However, there was significantly increased histamine-induced permeability in CD44-deficient mice compared to WT counterparts. Similar results were observed in vitro, where CD44-deficient endothelial monolayers were also impermeable to 40kD-FITC dextran in the absence of vasoactive challenge, but exhibited enhanced and prolonged permeability following histamine. However, CD44-KO monolayers have reduced baseline barrier strength by electrical resistance, which correlated with increased permeability, at baseline, to smaller molecular weight 4-kD FITC-dextran, suggesting weakly formed endothelial junctions. The CD44-KO EC displayed several characteristics consistent with impaired barrier function/dysfunctional EC junctions, including differential expression, phosphorylation, and localization of endothelial junction proteins, increased matrix metalloprotease expression, and altered cellular morphology. Reduced platelet endothelial cell adhesion molecule-1 (PECAM-1) expression by CD44-KO EC in vivo and in vitro was also observed. Reconstitution of murine CD44 or PECAM-1 restored these defects to near WT status, suggesting CD44 regulates vascular permeability and integrity through a PECAM-1 dependent mechanism.

Comprehensive characterization of the N-glycosylation status of CD44s by use of multiple mass spectrometry-based techniques

The CD44 family are type-1 transmembrane glycoproteins which are important in mediating the response of cells to their microenvironment, including regulation of growth, survival, differentiation, and motility. All these important functions have been reported to be regulated by N-glycosylation; however, little is known about this process. In the CD44 family, the most prolific isoform is CD44 standard type (CD44s). In this work, an integrated strategy combining stable isotope labeling, chemical derivatization, hydrophilic-interaction liquid chromatographic (HILIC) separation, and mass spectrometric (MS) identification was used to perform a comprehensive qualitative and quantitative survey of the N-glycosylation of recombinant CD44s. Specifically, the occupation ratios of the N-glycosites were first determined by MS with (18)O labeling; the results revealed five glycosites with different occupation ratios. Next, N-glycans were profiled by chemical derivatization and exoglycosidase digestion, followed by MALDI-TOF-MS and HILIC-ESI-MS-MS analysis. Interestingly, the quantitative analysis showed that non-sialylated, fucosylated complex-type glycans dominated the N-glycans of CD44s. Furthermore, the site-specific N-glycan distributions profiled by LC-ESI-MS(E) indicated that most glycosites bore complex-type glycans, except for glycosite N100, which was occupied by high-mannose-type N-glycans. This is the first comprehensive report of the N-glycosylation of CD44s. Figure Strategies for characterization of the N-glycosylation status of CD44s.

Clinicopathologic significance of putative stem cell markers, CD44 and nestin, in gastric adenocarcinoma

Cancer stem cells (CSC) are unique subpopulations that have the capacity to drive malignant progression and mediate radio/chemoresistance. The role of nestin as a CSC marker in gastric adenocarcinoma is largely unknown. Our objective was to evaluate immunoexpression of CSC markers CD44 and nestin in gastric adenocarcinoma versus non-neoplastic gastric mucosae (NNGM) and correlate it with various clinicopathologic factors. Tissue microarray blocks from 174 cases of gastric adenocarcinoma and 41 samples of adjacent NNGM were assembled. Clinical data including patient's age and sex, tumor histologic subtype and grade, and disease stage were obtained. Expression of CD44 and nestin was assessed by immunohistochemistry. Expression of membranous CD44 (51%, 78/152) and cytoplasmic nestin (25%, 43/174) was significantly greater in gastric adenocarcinoma than in NNGM (P<0.001). A subset of cases (n=15) that co-expressed membranous CD44 and cytoplasmic nestin were significantly more frequent in Lauren intestinal histologic subtype than in diffuse subtype (P<0.05). Foci of intestinal metaplasia (n=6) showed either CD44 (3/6) or nestin (2/6) expression. This is the first study to report the clinicopathologic significance of nestin expression in gastric cancers, and to correlate the nestin expression with CD44, another stem cell marker. The study shows that nestin and CD44, are significantly expressed in a subset of gastric adenocarcinoma, particularly co-expression of nestin and CD44 is significantly revealed in Lauren intestinal histologic subtype. Their expression is also increased in intestinal metaplasia, a premalignant lesion. These findings suggest that CSCs may have a pathogenetic role in the pathway of intestinal metaplasia-intestinal type gastric adenocarcinoma.

Met receptors induce Sam68-dependent cell migration by activation of alternate extracellular signal-regulated kinase family members

The hepatocyte growth factor (HGF)/Met receptor signaling pathway is deregulated in diverse human malignancies and plays a central role in oncogenesis, tumor progression, and invasive cancer growth. Similarly, altered expression and splicing (i.e. inclusion of variant exon 5, "v5") of the cell adhesion marker, CD44, is associated with advanced cancer phenotypes. We sought to further understand how HGF regulates CD44v5 expression. Immortalized nontumorigenic keratinocyte (HaCaT) cells abundantly express both Met receptors and CD44v5 transmembrane glycoproteins. HGF stimulated CD44v5 protein expression and HaCaT cell migration; these events required activation of the ERK1/2 MAPK module and Sam68, a protein involved in RNA processing, splicing, and v5 inclusion. Similar to HaCaT cells, highly migratory MDA-MB-231 breast cancer cells also required Sam68 expression for HGF-induced migration. However, MDA-MB-231 cell migration occurred independently of ERK1/2 and CD44v5 expression and instead required ERK5 signaling to Sam68. Phospho-mutant, but not WT-Sam68, blocked HGF-induced cell migration in both cell types; MDA-MB-435 cells behaved similarly. These results suggest that Sam68 acts as a convergence point for ERK signaling to cell migration; blockade of phospho-Sam68 may provide a new avenue for therapeutic inhibition of metastatic cancers.

HIV-1 p17 matrix protein interacts with heparan sulfate side chain of CD44v3, syndecan-2, and syndecan-4 proteoglycans expressed on human activated CD4+ T cells affecting tumor necrosis factor alpha and interleukin 2 production

HIV-1 p17 contains C- and N-terminal sequences with positively charged residues and a consensus cluster for heparin binding. We have previously demonstrated by affinity chromatography that HIV-1 p17 binds strongly to heparin-agarose at physiological pH and to human activated CD4(+) T cells. In this study we demonstrated that the viral protein binds to heparan sulfate side chains of syndecan-2, syndecan-4, and CD44v3 purified from HeLa cells and that these heparan sulfate proteoglycans (HSPGs) co-localize with HIV-1 p17 on activated human CD4(+) T cells by confocal fluorescence analysis. Moreover, we observed a stimulatory or inhibitory activity when CD4(+) T cells were activated with mitogens together with nanomolar or micromolar concentrations of the matrix protein.

Interaction of Golgin-84 with the COG complex mediates the intra-Golgi retrograde transport

The coiled-coil Golgi membrane protein golgin-84 functions as a tethering factor for coat protein I (COPI) vesicles. Protein interaction analyses have revealed that golgin-84 interacts with another tether, the conserved oligomeric Golgi (COG) complex, through its subunit Cog7. Therefore, we explored the function of golgin-84 as the tether for COPI vesicles of intra-Golgi retrograde traffic. First, glycosylic maturation of both plasma membrane (CD44) and lysosomal (lamp1) glycoproteins was distorted in golgin-84 knockdown (KD) cells. The depletion of golgin-84 caused fragmentation of the Golgi with the mislocalization of Golgi resident proteins, resulting in the accumulation of vesicles carrying intra-Golgi soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) and cis-Golgi membrane protein GPP130. Similar observations were obtained by diminution of the COG complex, suggesting a strong correlation between the two tethers. Indeed, COG complex-dependent (CCD) vesicles that accumulate in Cog3 or Cog7 KD cells carried golgin-84. Surprisingly, the interaction between golgin-84 and another candidate tethering partner CASP (CDP/cut alternatively spliced product) decreased in Cog3 KD cells. These results indicate that golgin-84 on COPI vesicles interact with the COG complex before SNARE assembly, suggesting that the interaction of golgin-84 with COG plays an important role in the tethering process of intra-Golgi retrograde vesicle traffic.

Regional topographical differences of canine microglial immunophenotype and function in the healthy spinal cord

Differences in the regulation of surface molecule expression and functional activity of microglia, the resident immune effector elements of the central nervous system (CNS), might give important insights into understanding the predilection sites of some diseases within the CNS. Therefore, canine microglial cells in relation to different topographical regions within the healthy CNS were evaluated ex vivo from the brain, cervical, and thoracolumbar spinal cord using density gradient centrifugation and flow cytometry in a homogenous dog population. Immunophenotypical characterization showed physiological regional differences for B7-1, CD14, CD44, CD1c, CD18, CD11b, and CD11c. Both, phagocytosis and ROS generation revealed differences between the brain, cervical, and thoracolumbar spinal cord. Our results emphasize that microglia displays physiological topographical regional differences within the CNS. The dog seems to be an ideal model to further investigate the role of microglia in focal pathological conditions of the spinal cord.