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Exosomes continue to attract interest as a promising nanocarrier drug delivery technology. They are naturally derived nanoscale extracellular vesicles with innate properties well suited to shuttle proteins, lipids, and nucleic acids between cells. Nonetheless, their clinical utility is currently limited by several major challenges, such as their inability to target tumor cells and a high proportion of clearance by the mononuclear phagocyte system (MPS) of the liver and spleen. To overcome these limitations, we developed "Smart Exosomes" that co-display RGD and CD47 p110–130 through CD9 engineering (Exo Smart ). The resultant Exo Smart demonstrates enhanced binding capacity to αvβ3 on pancreatic ductal adenocarcinoma (PDAC) cells, resulting in amplified cellular uptake in in vitro and in vivo models and increased chemotherapeutic efficacies. Simultaneously, Exo Smart significantly reduced liver and spleen clearance of exosomes by inhibiting macrophage phagocytosis via CD47 p110–130 interaction with signal regulatory proteins (SIRPα) on macrophages. These studies demonstrate that an engineered exosome drug delivery system increases PDAC therapeutic efficacy by enhancing active PDAC targeting and prolonging circulation times, and their findings hold tremendous translational potential for cancer therapy while providing a concrete foundation for future work utilizing novel peptide-engineered exosome strategies. Schematic illustration of ExoSmart enhances pancreatic cancer (PDAC) targeting while increase of evasion of mononuclear phagocyte system (MPS) clearance. (A) Diagram of ExoSmart; (B) Schematic diagram of ExoSmart working model; (C) Fluorescence imaging of liver, spleen and tumors of PDAC orthotopic mice that receive DiR stained exosomes via i.v. injection; (D) Immunofluorescence analysis of exosome in liver, spleen and tumors using anti-hemagglutinin (HA) antibody. [Display omitted] • A "Smart Exosome" that co-display RGD and CD47 p110–130 through CD9 engineering (Exo Smart ) was created. • The Exo Smart enhanced binding capacity to αvβ3 on PDAC cells, resulting in amplified cellular uptake in PDAC. • The Exo Smart significantly reduced liver and spleen clearance of exosomes by inhibiting macrophage phagocytosis. • The Exo Smart drug delivery system significantly increased PDAC therapeutic efficacy. [ABSTRACT FROM AUTHOR]

Recently, exosomes that are derived from bone marrow mesenchymal stem cells (BMSCs) have garnered considerable interest due to their significant roles in the processes of bone regeneration and repair. Among the various molecular components present within these exosomes, miR-668-3p has emerged as a pivotal microRNA that may be instrumental in modulating the function and proliferation of osteoblasts, the cells responsible for bone formation. The primary objective of this research was to examine the enhancing effects of BMSC-derived exosomes that are enriched with miR-668-3p on the advancement of osteoblasts in the context of osteonecrosis of the femoral head. Furthermore, the study aimed to analyze how the expression of specific exosomal proteins, namely CD63 and CD9, influences this biological process. To conduct the investigation, BMSCs were isolated from healthy rat models, followed by the extraction of their secreted exosomes. The subsequent phase of the study involved assessing the proliferation and differentiation of osteoblasts by introducing the exosomes enriched with miR-668-3p into an experimental setup representing osteonecrosis of the femoral head. The findings revealed that exosomes derived from BMSCs, which contained miR-668-3p, significantly enhanced the proliferation of osteoblasts as well as the expression of key osteogenic marker genes. Notably, the levels of CD63 and CD9 proteins were markedly increased in the treated groups, indicating that the mechanisms underlying this promotion might involve cell adhesion and the endocytic uptake of exosomes. [ABSTRACT FROM AUTHOR]

Advancing age is a negative prognostic factor for cutaneous melanoma. However, the role of extracellular vesicles (EVs) within the melanoma tumor microenvironment (TME) has remained unexplored in the context of aging. While the size and morphology of the EVs isolated from young vs. aged fibroblasts remained unaltered, the contents of the protein cargo were changed. Aging reduced the expression of the tetraspanin CD9 in both the dermal fibroblasts and released EVs. CD9 is a crucial regulator of EV cargo sorting. Modulating the CD9 expression in fibroblasts was sufficient to alter its levels in EVs. Mass spectrometry analysis of EVs released by CD9 knockdown (KD) vs. control cells revealed a significant increase in angiopoietin-like protein 2 (ANGPTL2), an angiogenesis promoter. Analysis of primary endothelial cells confirmed increased sprouting under CD9 KD conditions. Together, our data indicate that aged EVs play an important role in promoting a tumor-permissive microenvironment. [Display omitted] • Aging promotes a decline in CD9 expression in dermal fibroblast extracellular vesicles • Loss of CD9 drives secretion of the angiogenesis promotor ANGPTL2 in extracellular vesicles • Extracellular vesicles increase angiogenesis in melanoma in an age-dependent manner Hüser et al. show that an age-associated decline in CD9 expression in dermal fibroblasts promotes the secretion of CD9-low and ANGPTL2-high extracellular vesicles. The loss of CD9 promotes angiogenesis and presents an age-related mechanism, which could drive melanoma progression. [ABSTRACT FROM AUTHOR]

[Display omitted] • Schistosome infection could expand regulatory B cells (Bregs) in mice. • CD19±CD9± B cells produced more IL-10 than conventional B10 cells. • Adoptive transfer of CD9± B cells from infected mice had the capacity to markedly alleviate obesity-related inflammation. • CD9± B cells induced by helminth infection play a role in regulation of host metabolic disorders through IL-10 production. It has been shown that helminth infection can protect against obesity and improve insulin sensitivity to a certain extent, based on epidemiological investigations and animal experiments. Meanwhile, helminths induce a network of regulatory immune cells, including regulatory B cells (Bregs). However, the molecule characteristics and function of these Bregs in improving whole-body metabolic homeostasis remains largely unclear. We established a mouse model with chronic Schistosoma japonicum infection, and compared the differences in B10 cells (CD19+CD5+CD1dhi) and B10− cells (CD19+CD5−CD1d−) from splenic B cells of infected mice using RNA-seq. A unique Breg population was identified. Furthermore, these Bregs were evaluated for their ability to produce inhibitory cytokines in vitro and suppress obesity when adoptively transferred into mice on a high-fat diet. We found that schistosome infection could expand Breg cell populations in mice. CD9 was demonstrated to be a key surface marker for most murine IL-10+ B cells in spleen. CD19+CD9+ B cells produced more IL-10 than conventional B10 cells. Adoptive transfer of CD9+ B cells had the capacity to alleviate obesity-associated inflammation via promoting Tregs, Th2 cells and decreasing Th1, Th17 cells in high-fat diet mice. In conclusion, schistosome infection can induce regulatory CD9+ B cell production, which plays a critical role in the regulation of metabolic disorders through IL-10 production. [ABSTRACT FROM AUTHOR]

Abstract Tetraspanins are multifunctional molecules located in specific microdomains on the plasma membrane. Thanks to their ability to form networks with other proteins they can participate in many cellular functions. Tetraspanins are part of the interactive network in gametes; however, their precise role in fertilization is not yet clear. The aim of this study was to compare the localization of CD9 and CD81 tetraspanins during oocyte maturation and early development of the embryos in bovine and porcine model. CD9 was detected on the oocyte plasma membrane and vesicles in the perivitelline space of bovine oocytes and embryos. We suggest that CD9 could be a component involved in transzonal projections. Based on the results of in vitro fertilization assay, CD9 and CD81 seem to be part of a more complex fusion network on the plasma membrane of bovine oocytes. On the other hand, both tetraspanins showed a clustered expression pattern on the plasma membrane and inner margin of zona pellucida (ZP) in porcine oocytes and embryos. We found a new species-specific pattern of CD9 and CD81 distribution in ZP which could reflect their specialized role in processes associated with cell adhesion and intercellular communication upon fertilization. [ABSTRACT FROM AUTHOR]

The objectives of the present study were to evaluate the developmental competence of buffalo denuded oocytes (DOs) cocultured with cumulus cells (CCs) during in vitro maturation, and to investigate the mechanisms by which CCs promote oocyte maturation and development. Buffalo oocytes were matured in vitro for 24 h in three groups: (1) intact cumulus–oocyte complexes (COCs) (2) DOs cocultured with CCs (DOsCC), and (3) DOs cultured alone (DOs). Matured oocytes were used to determine the relative mRNA abundance of Gdf-9 , Bmp15 , Zar1 , Caspase-3 , Bcl-2 , Zp2 , Zp3 , Cd9 and Pde3a by Rt-qPCR and CASPASE-3 protein expression by immunofluorescence. The intracellular content of cGMP, cAMP and MPF activity and the rate of embryonic development were also assessed. Results of the present study showed that in DOs, the relative mRNA abundance of Gdf-9 , Bmp15, and Cd9 significantly ( P  < 0.05) decreased, whereas Caspase-3 (mRNA and protein levels), Bcl-2 , and Pde3a exhibited higher expression than DOsCC and COCs. However, there was no significant difference among the groups in the expression level of Zar-1 , Zp2 , and Zp3 . The intracellular content of cAMP and MPF activity was notably higher ( P  < 0.05) in DOs compared to COCs and DOsCC. There was no significant difference between COCs and DOsCC in cGMP content, which was significantly lower ( P  < 0.05) in DOs. Moreover, the cleavage and blastocyst rates were 58.4 ± 1.8%, 43.7 ± 1.1%, 18.4 ± 0.9% and 18.0 ± 1.3%, 11.0 ± 0.9% and 4.5 ± 0.6% in COCs, DOsCC and DOs groups, respectively. In conclusion, the presence of CCs protects buffalo DOs from apoptosis and promotes maturation through regulation of the intracellular content of cAMP and MPF activity and improves the fertilizing capacity of oocytes through modulation of the gamete fusion gene, Cd9 . [ABSTRACT FROM AUTHOR]

CD9 is a member of the tetraspanin family, which is characterised by a unique domain structure and conserved motifs. In mammals, CD9 is found in tetraspanin-enriched microdomains (TEMs) on the surface of virtually every cell type. CD9 has a wide variety of roles, including functions within the immune system. Here we show the first in-depth analysis of the cd9 gene family in salmonids, showing that this gene has expanded to six paralogues in three groups (cd9a , cd9b , cd9c) through whole genome duplication events. We suggest that through genome duplications, cd9 has undergone subfunctionalisation in the paralogues and that cd9c1 and cd9c2 in particular are involved in antiviral responses in salmonid fish. We show that these paralogues are significantly upregulated in parallel to classic interferon-stimulated genes (ISGs) active in the antiviral response. Expression analysis of cd9 may therefore become an interesting target to assess teleost responses to viruses. • Salmonids have six CD9 paralogues organised in three clades (cd9a, cd9b and cd9c). • Phylogenetic analysis indicate cd9a and cd9b clades appeared prior to the teleost specific whole genome duplication (Ts3R). • The cd9c clade, however, may have appeared first after Ts3R. • Promoter analysis and RNAseq gene expression suggest an antiviral role of cd9c1 and cd9c2. [ABSTRACT FROM AUTHOR]

The most prevalent locations for head and neck cancer is the tongue. The surviving patients who are receiving therapy have considerably compromised speech, taste, chewing, and swallowing. CD9 is a cell surface protein that has contradictory role in cancer progression. The objective of the study is to analyze the Cluster of Differentiation 9(CD9), Epidermal Growth Factor Receptor (EGFR) and Phosphorylated Akt (p-Akt) expression in tongue cancer specimens and its clinical significance.50 tongue cancer sections were used to analyze the expression of CD9,EGFR and p-Akt by immunohistochemistry. Data regarding the histological grade of the tumor, age, sex, and habits were recorded, and relation with CD9,EGFR and p-Akt expression was assessed. Data were expressed as mean ± SEM. Categorical data was analyzed by Chi-square test. Student t-test was used to check the significance of data between two groups.A significant increase in the CD9,EGFR and p-Akt expression (1.8 ± 0.11, 2.06 ± 0.18 and 2.3 ± 0.15 respectively) was seen in the tongue cancer specimens. CD9 and p-Akt expression had a significant association with the histological grade (p < 0.004 and p < 0.006 respectively). CD9 expression was higher in patients with the combination of addiction/habit compared to patients with single addictions(1.08 ± 0.11 and 0.75 ± 0.47). Overall a poor rate of survival was observed in CD9 positive patients(p < 0.039). EGFR and p-Akt expression increased with increasing expression of CD9, suggesting its use as a biomarker to track the development of TSCC. [ABSTRACT FROM AUTHOR]

During human placentation, the extravillous trophoblast (EVT) invades the maternal decidua and reconstructs maternal spiral arteries. However, the precise mechanisms that control EVT behavior have not yet been elucidated in detail. CD9 has been reported to be a cell-motility-related molecule. Since we previously observed that CD9 was expressed on human EVT, we examined the possible involvement of CD9 in the invasion process of EVT. Placental and umbilical samples were obtained from patients who underwent legal abortions, normal delivery, or hysterectomy. The expression of CD9 at the implantation site and on isolated EVT from a villous explant culture, an EVT-derived immortalized cell line, Swan71, and HUVEC was examined by immunocytochemical staining, flow cytometry, and RT-PCR. The effects of anti-CD9 functional antibody (ALB6) on EVT and Swan71 cell invasion were further examined by matrigel invasion assay along with shRNAmir gene knockdown treatment. CD9 was highly expressed on EVT at the boundary region of EVT invasion and intravascular EVT. EVT and Swan71 cell invasions were promoted by ALB6 or shRNAmir treatment. CD9 expression on Swan71 cells was reduced under hypo-oxygenic conditions, while its expression was increased by the co-culture with HUVEC. These findings suggest that CD9 could attenuate EVT invasion under the influence of an oxygen environment and maternal endothelial cells, proposing that CD9 is a potential regulator of human placental formation. [ABSTRACT FROM AUTHOR]

The oolemma of the second metaphase mouse oocyte has a relatively large domain in the peri-polar body region that is non-permissive for sperm attachment. In this study, certain biochemical components of this non-permissive domain were examined and compared with permissive regions to investigate the molecular basis of an oolemma that becomes functionally polarized during fertilization; an attempt was also made to determine whether similarities exist in the formation of abnormally occurring non-permissive domains in human oocytes. In the present study, microdomains composed of lipid rafts enriched in the ganglioside GM1 provided a platform for sperm docking at the initial stage of fertilization and their disruption led to sperm attachment defects resembling those associated with fertilization failure in human IVF. The regulation of GM1 microdomain density is suggested to involve the oolemmal protein annexin 2 and the magnitude of the inner mitochondrial membrane potential (ΔΨm) in the adjacent subplasmalemmal cytoplasm. These studies also showed that a rapid focal reduction in GM1, f-actin, annexin 2 and cholesterol occurs at the site of sperm docking and attachment whereas the distribution of fertilization-associated proteins CD9 and FOLR4 remains unchanged, suggesting that they may not participate in the earliest phases of fertilization. [ABSTRACT FROM AUTHOR]

Virus-like particles (VLPs) are a particular subset of subunit vaccines which are currently explored as safer alternatives to live attenuated or inactivated vaccines. VLPs derived from retrovirus (retroVLPs) are commonly used as scaffolds for vaccine candidates due to their ability to incorporate heterologous envelope proteins. Pseudotyping retroVLPs is however not a selective process therefore, host cellular proteins such as tetraspanins are also included in the membrane. The contribution of these host-proteins to retrovirus immunogenicity remains unclear. In this work, human cells silenced and not silenced for tetraspanin CD81 were used to produce CD81 − or CD81 + retroVLPs. We first analyzed mice immune response against human CD81. Despite effective silencing of CD81 in retroVLP producing cells, both humoral and cellular immune responses showed persistent anti-CD81 immunogenicity, suggesting cross reactivity to related antigens. We thus compared the incorporation of related tetraspanins in retroVLPs and showed that decreased CD81 incorporation in CD81 − retro-VLPs is compensated by an increased incorporation of CD9 and CD63 tetraspanins. These results highlight the dynamic nature of host-derived proteins incorporation in retroVLPs membrane, which should be considered when retrovirus-based biopharmaceuticals are produced in xenogeneic cells. [ABSTRACT FROM AUTHOR]

Acute lymphoblastic leukemias (ALL) are the most frequent cancer in children and derive most often from B-cell precursors. Current survival rates roughly reach 90% at 10 years from diagnosis. However, 15–20% of children still relapse with a significant risk of death. Our previous work showed that the transmembrane protein CD9 plays a major role in lymphoblasts migration into sanctuary sites, especially in testis, through the activation of RAC1 signaling upon blasts stimulation with C-X-C chemokine ligand 12 (CXCL12). Here, we identified common factors shared by the bone marrow and extramedullary niches which could upregulate CD9 expression and function. We found that low oxygen levels enhance CD9 expression both at mRNA and protein levels. We further determined that Hypoxia Inducible Factor 1α (HIF1α), the master transcription factor involved in hypoxia response, binds directly CD9 promoter and induce CD9 transcription. We also showed that CD9 protein is crucial for leukemic cell adhesion and migration at low oxygen levels, possibly through its action on RAC1 signaling. Mouse xenograft experiments indicate that HIF1α signaling pathway promotes ALL cells engraftment in a CD9-dependent manner. The present work increments our understanding of CD9 implication in ALL pathogenesis. • Tetraspanin CD9 expression is regulated by low O 2. • The Hypoxia Inducible Factor 1α (HIF1α) signaling pathway is directly involved. • CD9-mediated migration and dissemination depends on the HIF1α signaling pathway. [ABSTRACT FROM AUTHOR]

The tetraspanin CD9 has been shown to interact with different members of the β1 and β3 subfamilies of integrins, regulating through these interactions cell adhesion, migration and signaling. Based on confocal microscopy co-localization and on co-immunoprecipitation results, we report here that CD9 associates with the β2 integrin LFA-1 in different types of leukocytes including T, B and monocytic cells. This association is resistant to stringent solubilization conditions which, together with data from chemical crosslinking, in situ Proximity Ligation Assays and pull-down experiments, suggest a primary/direct type of interaction mediated by the Large Extracellular Loop of the tetraspanin. CD9 exerts inhibitory effects on the adhesive function of LFA-1 and on LFA-1-dependent leukocyte cytotoxic activity. The mechanism responsible for this negative regulation exerted by CD9 on LFA-1 adhesion does not involve changes in the affinity state of this integrin but seems to be related to alterations in its state of aggregation. [ABSTRACT FROM AUTHOR]

Tetraspanins are a family of membrane-organizing proteins, characterized by the presence of four highly conserved transmembrane regions that mediate diverse physiological functions. In the current study, we have identified two novel tetraspanin members in rainbow trout ( Oncorhynchus mykiss ), homologs to mammalian CD9 and CD63. Both genes were expressed in muscle, skin, gills, hindgut, gonad, liver, spleen, head kidney, thymus and peripheral blood leukocytes. Throughout the early life cycle stages, CD9 mRNA levels significantly increased after first feeding, whereas CD63 transcription remained constant during all the developmental stages analyzed. In response to an experimental bath infection with viral hemorrhagic septicemia virus (VHSV), CD9 transcription was down-regulated in the gills, while CD63 mRNA levels were down-regulated in the head kidney. Instead, when the virus was intraperitoneally injected, the transcription of both genes was significantly up-regulated in peritoneal cells at several days post-infection. Additionally, both genes were transcriptionally up-regulated in the muscle of trout injected with a VHSV DNA vaccine. To gain insight on the relation of these tetraspanins with B cell activity we determined their constitutive expression in naive IgM + populations from different sources and observed that both molecules were being transcribed by IgM + cells in different tissues. Furthermore, CD9 transcription was significantly down-regulated in splenic IgM + cells in response to in vitro VHSV exposure. Our results provide insights on the potential role of these tetraspanins on teleost B cell and antiviral immunity. [ABSTRACT FROM AUTHOR]

In this report, we describe the characterization of a new monoclonal antibody, named 4H5CR4, against porcine CD9. Its use in combination with antibodies to CD4, CD8α, and 2E3 allows to distinguish at least five main CD4+ T cell subsets. Analysis on these subsets of CD45RA, CD27, CD29, CD95, CCR7, and SLA-DR markers depicts a progressive model of CD4+ T cell development. CD4+ 2E3+ CD8α− CD9− cells are the least differentiated population of naïve cells, whereas the CD4+ 2E3− CD8α+CD9+ and CD4+ 2E3− CD8α+ CD9− cells display phenotypic features of central and effector memory T helper cells, respectively. The latter subsets were able to produce IFN-γ after polyclonal activation with PMA/Ionomycin; however, in vitro virus-specific IFN-γ production of PBMCs collected at 38–44 days after pseudorabies virus vaccination was dominated by cells with a CD9+ phenotype. Therefore, CD9 appears to be a useful marker to investigate CD4+ T cell heterogeneity in swine. • A new anti-porcine CD9 mAb has been characterized. • Expression of CD9, 2E3 and CD8α markers delineates a CD4+ T cell development pathway. • CD4+ CD8α+ 2E3- CD9+ T cells display phenotypic features of central memory T cells. • CD4+ CD8α+ 2E3- CD9− T cells display phenotypic features of effector memory T cells. [ABSTRACT FROM AUTHOR]

Abstract: CD9 and CD82, members of the tetraspanin family, act as metastasis suppressors in many human malignant tumors, but the role of these molecules is not well known in clear cell renal cell carcinoma (CCRCC). This study was designed to evaluate the immunohistochemical expression of CD9 and CD82 in 644 cases of CCRCC and to determine the clinicopathologic and prognostic significance of their expression. The percentage of positive tumor cells was evaluated, and the expression was classified into 2 categories: low expression (less than 10% positive cells) or high expression (more than 10% positive cells) for CD9 expression and negative (no positive cells) or positive for CD82 expression. CD9 high expression was found in 303 (47.0%) patients, and CD82 positivity was found in 98 (15.2%) patients. High expression of CD9 was statistically associated with older patients (p =0.003). The cases showing positive immunoreactivity for CD82 exhibited a high stage (p <0.001) and high nuclear grade (p <0.001). The overall, cancer-specific and progression-free survival rates were significantly higher in patients with a CD82-negative profile compared to patients with a CD82-positive profile (p <0.001). Although the biological function of CD82 in CCRCC remains unclear, the CCRCC patients with CD82 positive expression show poor prognosis. [Copyright &y& Elsevier]

The emerging notion of hematopoietic stem and progenitor cells (HSPCs) as a low-primed cloud without sharply demarcated gene expression programs raises the question on how cellular-fate options emerge and at which stem-like stage lineage priming is initiated. Here, we investigate single-cell chromatin accessibility of Lineage−, cKit+, and Sca1+ (LSK) HSPCs spanning the early differentiation landscape. Application of a signal-processing algorithm to detect transition points corresponding to massive alterations in accessibility of 571 transcription factor motifs reveals a population of LSK FMS-like tyrosine kinase 3 (Flt3)intCD9high cells that concurrently display stem-like and lineage-affiliated chromatin signatures, pointing to a simultaneous gain of both lympho-myeloid and megakaryocyte-erythroid programs. Molecularly and functionally, these cells position between stem cells and committed progenitors and display multi-lineage capacity in vitro and in vivo but lack self-renewal activity. This integrative molecular analysis resolves the heterogeneity of cells along hematopoietic differentiation and permits investigation of chromatin-mediated transition between multipotency and lineage restriction. [Display omitted] • Distinct chromatin landscapes separate hematopoietic stem and progenitor populations • LSKFlt3intCD9high cells display concurrent stem- and multi-lineage chromatin • LSKFlt3intCD9high cells bridge multipotency and lineage restriction Safi et al. reveal a unique hematopoietic transition state, displaying concurrent stem- and multi-lineage chromatin-accessibility signatures captured by LSKFlt3intCD9high immunophenotype. LSKFlt3intCD9high cells represent extensively primed progenitors lacking self-renewal but bridging multipotency and lineage restriction. These findings permit analysis of how self-renewal and multipotency are lost in favor of lineage commitment. [ABSTRACT FROM AUTHOR]

The roles of oolemmal lipid raft microdomains enriched in the ganglioside GM1 and the tetraspanin protein CD9 were investigated as causative agents in fertilization failure in human IVF where spermatozoa progress to the oolemma but fail to attach or, if attached, to penetrate. The findings show that specific configurations of GM1 lipid raft microdomains are consistent with attachment and penetration, while microdomains composed of CD9 lipid rafts, a protein known to be critical for penetration, do not appear to have a central role in the initial stages of attachment. The relative magnitude of the potential difference across the inner membrane (ΔΨm) in mitochondria localized to a stable subplasmalemmal domain appears to influence the organization of GM1 but not CD9 lipid raft microdomains in the corresponding oolemma. The findings present a novel view of how fertilization competence may be established in the human oocyte and a means by which certain fertilization failures that occur after conventional clinical IVF can be identified and explained in the unfortunate instance of fertilization arrest at the oolemma. [ABSTRACT FROM AUTHOR]

Abstract: Osteoclast differentiation is influenced by receptor activator of the NF-κB ligand (RANKL), macrophage colony-stimulating factor (M-CSF), and CD9, which are expressed on bone marrow stromal cells and osteoblasts. In addition, osteoprotegerin (OPG) is known as an osteoclastogenesis inhibitory factor. In this study, we investigated whether bisphosphonates and statins increase OPG expression and inhibit the expression of CD9, M-CSF, and RANKL in the bone marrow-derived stromal cell line ST2. We found that bisphosphonates and statins enhanced OPG mRNA expression and inhibited the expression of CD9, M-CSF, and RANKL mRNA. Futhermore, bisphosphonates and statins decreased the membrane localization of Ras and phosphorylated ERK1/2, and activated the p38MAPK. This indicates that bisphosphonates and statins enhanced OPG expression, and inhibited the expression of CD9, M-CSF, and RANKL through blocking the Ras/ERK pathway and activating p38MAPK. Accordingly, we believe that its clinical applications will be investigated in the future for the development of osteoporosis therapy. [Copyright &y& Elsevier]

Objective: To determine the physiological role of IGSF8 for fertility. Design: Experimental prospective study. Setting: Academic basic research laboratory. Animal(s): C57BL/6J and hybrid B6D2F1 mice, as well as Cd9 and Igsf8 knockout mice (C57BL/6J and 129/SvJ mix background), were used for this study. Intervention(s): None. Main Outcome Measure(s): In vitro and in vivo fertility tests of Igsf8 knockout mice. Result(s): Tetraspanin family member CD9 plays an important role in sperm-egg fusion. Recently, some researchers have reported that CD9 tightly associates with the immunoglobulin superfamily member IGSF8 on the egg surface and that IGSF8 is undetectable on the surface of Cd9-deficient eggs. This led us to hypothesize that IGSF8 participates in sperm-egg fusion together with CD9. To examine the physiological role of IGSF8 in vivo, we generated Igsf8-deficient mice by homologous recombination and examined the fertility of the females. Conclusion(s): The Igsf8-deficient female mice showed no fertilization defect in vitro or in vivo. We observed that Igsf8-deficient eggs retained the normal level and localization of CD9, resulting in normal microvilli formation, which indicates that IGSF8 is dispensable in fertility. [ABSTRACT FROM AUTHOR]

Abstract: In primates and rodents, trophoblast cells synthesize and secrete into the maternal circulation a family of proteins known as pregnancy specific glycoproteins (PSG). The current study was undertaken to characterize the receptor for two members of the murine PSG family, PSG17 and PSG23. Binding of recombinant PSG17 and PSG23 to CHO-K1 and L929 cells and their derived mutants was performed to determine whether these proteins bound to cell surface proteoglycans. We also examined binding of these proteins to cells transfected with syndecans and glypican-1 by flow cytometry. The interaction with glycosaminoglycans was confirmed in solid phase assays. Our results show that PSG17 binds to CD9 and to cell surface proteoglycans while PSG23 binds only to the latter. We found that the amino acids involved in CD9 binding reside in the region of highest divergence between the N1-domains of murine PSGs. For both proteins, the N-terminal domain (designated as N1) is sufficient for binding to cells and the ability to bind cell surface proteoglycans is affected by the cell line employed to generate the recombinant proteins. We conclude that while substantially different at the amino acid level, some murine PSGs share with human PSG1 the ability to bind to cell surface proteoglycans and that at least one PSG binds to more than one type of molecule on the cell surface. [Copyright &y& Elsevier]

Abstract: Abnormal gene promoter methylation contributes to deregulate gene expression of hematopoietic progenitors in myelodysplastic syndromes (MDS). We analyzed the gene expression profile of myelodysplastic and normal CD34+ hematopoietic stem cells (HSCs) treated in vitro with decitabine. We identified a list of candidate tumor suppressor genes, expressed at low levels in MDS HSCs and induced by hypomethylating treatment only in MDS, but not in normal HSCs. Real-time RT-PCR confirmed reduced CD9 expression in MDS CD34+ and bone marrow mononuclear cells, compared to normal controls. CD9 was specifically up-regulated by decitabine treatment in myelodysplastic CD34+ cells. [Copyright &y& Elsevier]

Abstract: CD9 is a member of the tetraspanin family and is widely expressed in the plasma membrane of several cell types as well as malignant cells. CD9 associates with a number of transmembrane proteins, which facilitates biological processes, including cell signaling, adhesion, migration and proliferation. DDR1 is activated by native type IV collagen and overexpressed in human breast cancer. Type IV collagen is the main component of basement membranes, and may interact with cell surface biomolecules, promoting adhesion and motility. However, the role of DDR1 and type IV collagen in the regulation of CD9-cell surface levels and migration in breast cancer cells has not been studied in detail. We demonstrate here that native type IV collagen induces a transient increase of CD9-cell surface levels through a DDR1-dependent pathway in MDA-MB-231 breast cancer cells, as revealed by flow cytometry and Western blotting using specific antibodies that recognize CD9. In contrast, type IV collagen does not induce any increase of CD9-cell surface levels in the mammary non-tumorigenic epithelial cells MCF10A and MCF12A. Transient increase of CD9-cell surface levels is coupled with clathrin-mediated endocytosis and it is dependent of DDR1 expression. In addition, type IV collagen induces cell migration through a DDR1 and CD9-dependent pathway. In summary, our data demonstrate, for the first time, that native type IV collagen induces a transient increase of CD9-cell surface levels and cell migration through a DDR1 and CD9-dependent pathway in MDA-MB-231 breast cancer cells. [Copyright &y& Elsevier]

Abstract: CD9 has been shown to be differentially expressed in childhood TEL/AML1-positive acute lymphoblastic leukemia (ALL). We confirmed this finding in large Affymetrix data sets and in 80 new cases at both RNA and protein levels. Moreover, we showed that mean fluorescence intensity of CD9 by flow cytometry can distinguish TEL/AML1-positive ALL from other BCP-ALL. Using ROC analysis, the most efficient model for predicting TEL/AML1-positive ALL combined CD9 (mean fluorescence intensity ≤20) and CD10 values (positive cells >40%). Finally, we propose a faster procedure for optimizing the diagnosis of childhood BCP-ALL subgroups. [Copyright &y& Elsevier]

Summary: Squamous cell carcinoma of the oral cavity (OSCC) is a malignancy characterized by a high degree of local aggression and metastasis to cervical lymph nodes. Tetraspanins are proteins with functional roles in a wide array of cellular processes and are reported to be associated with tumor progression. The present study investigated the expression of the CD9, CD37, CD63, CD81 and CD82 tetraspanins in OSCC using immunohistochemistry (IHC) and quantitative Real Time-PCR (qRT-PCR). Tissue microarray (TMA) analysis of samples from 179 cases of OSCC and 10 normal samples oral mucosa were evaluated immunomorphologically. We analyzed CD9 and CD82 expression by qRT-PCR in 66 OSCC cases and 4 normal samples of oral mucosa. Expression of CD63, CD37 and CD81 was not detected in the samples studied. CD82 was downregulated or negative in 127 of 179 (80%) specimens; no correlation was observed between CD82 expression, clinicopathological parameters, disease-free survival and 5-year overall survival. CD9 expression was downregulated or negative in 75 of 129 (42%) OSCC samples. Loss of CD9 expression in OSCC samples correlated with the incidence of lymph node metastasis (p =0.017). Disease-free survival and the 5-year overall survival of patients with downregulated or negative CD9 expression were significantly lower than in patients with positive CD9 expression (p =0.010 and p =0.071, respectively). No correlation was found between CD9 or CD82 expression and clinicopathological parameters by qRT-PCR. Our results suggest that the downregulation or lack of expression of the CD9 protein might indicate a more aggressive of OSCC. [Copyright &y& Elsevier]

Abstract: CD63 and CD9 are members of the tetraspanin superfamily of integral membrane proteins that function as organizers of multi-molecular signaling complexes involved in cell morphology, motility and proliferation. Tetraspanin complexes cluster dynamically in unique cholesterol-rich tetraspanin-enriched microdomains (TEMs). In resting platelets, CD63 is located in the membranes of lysosomes and dense granules. Following platelet activation and granule exocytosis, CD63 is expressed on the plasma membrane, co-localizes with the αIIbβ3-CD9 complex and is incorporated into the Triton-insoluble actin cytoskeleton, dependent on fibrinogen binding to αIIbβ3. In nucleated cell lines, the assembly and maintenance of TEMs depends on the palmitoylation of both tetraspanins and some partner proteins. This study investigated the role of palmitoylation in platelet TEM assembly and maintenance. [3H]-palmitate-labeled, washed human platelets were studied at rest, or following activation with thrombin (0.1 U/ml). CD63 and CD9 were separated by density gradient centrifugation, isolated by immunoprecipitation, and [3H]-palmitate was measured in each fraction. Palmitate levels increased in all fractions following thrombin activation. However, the relative inter-fraction distribution of the tetraspanins did not change. 2-bromopalmitate (2-BP), an inhibitor of protein palmitoylation as demonstrated by decreased [3H]-palmitate labeling of platelet proteins, blocked both thrombin-induced platelet aggregation and platelet spreading on immobilized fibrinogen in a dose-dependent manner. 2-BP also inhibited the activation-dependent association of CD63 with CD9, and the incorporation of CD63 into the Triton-insoluble actin cytoskeleton. In contrast, 2-BP had no effect on the incorporation of αIIbβ3 into the activated platelet cytoskeleton. These results demonstrate that palmitoylation is required for platelet tetraspanin-tetraspanin and tetraspanin-integrin interaction and for complete platelet spreading on a fibrinogen substrate. [Copyright &y& Elsevier]

Abstract: In this study, a CD9 homologue in a reptile, Chinese soft-shelled turtle, has been cloned and identified for the first time. The full-length cDNA of turtle CD9 was 1146bp and contained a 672bp open reading frame (ORF) coding for a protein of 224 amino acids. Four transmembrane domains (TMs) divided the turtle CD9 into several parts: short N-, C-termini, an intracellular loop and two (small and large) extracellular loops (SEL and LEL). A CCG motif, a potential N-linked glycosylation site and 10 cysteine residues were well conserved. The deduced amino acid sequence analysis showed that the turtle CD9 shared 82% identity to duck CD9. Most of the differences were found in the LEL. Phylogenetic analysis showed that the turtle CD9 sequence clustered together with bird CD9 sequence. RT-PCR analysis showed that turtle CD9 was ubiquitously expressed in liver, spleen, kidney, heart, blood and intestine tissues of un-infected turtles. Real-time PCR analysis further indicated that after Aeromonas hydrophila infection, the turtle CD9 mRNA was up-regulated in various tissues at 8h, and significantly up-regulated during 8h to 7d. These results indicated that turtle CD9 may be involved in anti-bacterial immune response. [Copyright &y& Elsevier]

Abstract: Vascular smooth muscle cell (VSMC) migration and proliferation are critical events in the development of neointima following vascular injury. In this study, we found that CD9 is constitutively expressed in the VSMC of the neointima of injured carotid arteries. The in vitro migration and proliferation of human coronary artery smooth muscle (hCASM) cells were reduced by 40% and 63%, respectively, by treatment with a CD9 specific monoclonal antibody mAb7 when compared to control antibody treatment. In a mouse carotid ligation injury model, a single application of a neutralizing anti-mouse CD9 antibody resulted in a 31% (day 14, n =8, p <0.05), and 32% (day 28, n =5, p <0.01) reduction in neointima formation. In support of these findings, exogenous expression of human CD9 by CD9-adenoviral transduction led to 43% increases in neointima (p <0.05, n =6). Upon investigation of the mechanisms underlying CD9 mediated VSMC phenotypic events we found that integrin α5β1 was a constitutive partner of CD9 and that CD9 significantly augmented PI-3 kinase dependent Akt phosphorylation. Furthermore, enhanced Akt phosphorylation was attenuated by mAb7 binding. Cumulatively, a functional link between CD9, α5β1, PI3-K/Akt activity and enhanced VSMC migratory and proliferative phenotypes has been demonstrated. These studies suggest that agents that modulate CD9 mediated VSMC phenotypes may emerge as novel strategies for the treatment of abnormal vascular injury response. [Copyright &y& Elsevier]

Objective: To examine the spatiotemporal expression of CD9 protein in the peri-implantation mouse uterus as well as the effects of ovarian steroid hormones on CD9. Design: Experimental animal study. Setting: Reproductive biological center of Chinese Academy of Sciences. Animal(s): Female Kunming white strain mice (6–8 weeks old). Intervention(s): Subcutaneous injection of P4/E2; uterine tissues were collected at different times after injection. Main Outcome Measure(s): The levels of protein and mRNA were detected in mouse uterus during peri-implantation and after steroid hormones treatment. Result(s): CD9 protein was expressed intensely in the stromal cells on days 1 and 2 of pregnancy. On days 3 and 4, the glandular and luminal epithelial cells exhibited accumulation of CD9 protein. After the initial attachment reaction on day 5, luminal epithelial and stromal cells immediately surrounding the blastocysts exhibited distinct accumulation of CD9. On days 6–8, the accumulation of CD9 occurred in decidual cells. Using ovariectomized mice, we also observed that both progesterone and estrogen upregulated uterine CD9 expression. Conclusion(s): The results of the current investigation showed that CD9 was differentially expressed in the uterus depending on the stage of implantation and was upregulated in ovarian steroid hormone–dependent manner, implicating multiple roles of CD9 in the regulation of embryo implantation during the peri-implantation period. [Copyright &y& Elsevier]

Abstract: CD9 is a glycoprotein of the transmembrane 4 superfamily (TM4SF) and is involved in various cellular processes. In this study, we describe the isolation of the full-length cDNA encoding for CD9 molecule (daCD9) of red stingray, Dasyatis akajei. This 1252bp cDNA was isolated from leukocyte cDNA library and contains 681bp open reading frame encoding 226 amino acid residues. Amino acid sequences analysis and structure prediction display approximately 50% identity to higher vertebrates with the presence of conserved structures, including the four transmembrane domains and certain characteristic residues. Southern blot analysis shows that daCD9 exists as a single copy gene. Northern blot analysis reveals that daCD9 is highly expressed in gill and spleen although its expression can be found in other tissues suggesting daCD9 might play an important role in immune defense in this fish. [Copyright &y& Elsevier]

Tetraspanins CD9 and CD151 have been implicated in cellular motility and intercellular adhesion in several cellular types. Here, we have studied the subcellular localization and the functional role of these molecules in primary melanocytes. We found that endogenous tetraspanins preferentially clustered in areas of melanocyte homotypic intercellular contacts and at the tips of dendrites. These observations were further confirmed using time-lapse fluorescence confocal microscopy of melanocytes transfected with CD9– and CD151–GFP (green fluorescent protein) constructs, suggesting an involvement of these proteins in cellular contacts and migration. Cell adhesion and migration assays performed using blocking monoclonal antibodies against CD9 and CD151 showed no significant effect on cell–extracellular matrix adhesion, whereas the migration of melanocytes was significantly enhanced. The regulation of the migratory capacity of melanocytes by CD9 and CD151 was further confirmed knocking down the endogenous expression of these tetraspanins with small interference RNA oligonucleotides. Therefore, tetraspanin molecules are localized at motile structures in primary human melanocytes regulating the migratory capacity of these cells. [ABSTRACT FROM AUTHOR]

Abstract: The number of endoprosthesis revision operations is increasing. In a previous analysis using cDNA microarrays, differentially expressed genes were detected in the wear-particle-induced membrane and in the infectious periprosthetic membrane. This study aims at validation of these gene expression profiles in order to find genes that are potentially relevant for the pathogenesis, diagnosis, or therapy of endoprosthesis loosening. Tissue samples from 16 wear-particle-induced and 20 infectious periprosthetic membranes were analyzed by reverse transcription polymerase chain reaction (RT-PCR), in situ hybridization, and immunohistochemistry with regard to the expression of CD9, CD11b, CD18, CD52, and platelet-derived growth factor (PDGFR)-?. RT-PCR demonstrated cd9, cd11b, cd18, cd52, and pdgfr-? RNA in all samples. Macrophages and multinuclear giant cells in the wear-particle-induced membranes showed intense immunohistochemical staining for CD9, CD11b, and CD52. The staining of PDGFR-? was stronger in the infectious membranes, whereas there were no differences for CD18. Using RT-PCR and immunohistochemical analysis, the cDNA-microarray data of cd9, cd11b, cd52, and pdgfr-? could be validated, whereas the differential expression of cd18 was not confirmed. The potential relevance of these genes for prosthesis loosening is discussed. [Copyright &y& Elsevier]

CD 9, also known as Motility-Related Protein-1 (MRP-1), is a member of the transmembrane four superfamily and plays a crucial role in cell adhesion, motility and signalling events. Downregulation of CD 9 has been reported to be associated with tumour progression, metastasis and clinical outcome in various kinds of solid tumours.Although prognosis of osteosarcoma has been improved by chemotherapy during the last decades, the problem of non-responders remains. At the present time prognostic factors at diagnosis have not been clearly identified. Furthermore, there is a need for markers that predict the response to chemotherapy at the time of biopsy, allowing stratification of osteosarcoma patients. In this study we investigated the effect of CD9 expression on the response to chemotherapy and survival in osteosarcoma. The expression of CD9 was examined immunohistochemically in 52 patients with high grade osteosarcoma and the results were correlated with histologic response to chemotherapy, 5 year disease free and 5 year overall survival. In patients with osteosarcoma 22 of 52 cases (42%) were positive for CD 9 expression, the rest were negative. CD 9 expression status showed no statistically significant correlation with response to chemotherapy; 41% had a poor response and 59% a good response in the CD9 positive group. In the CD9 negative group 57% had a good and 47% had a bad response. No significant difference was found when comparing disease free survival (58.9% in CD9 positive- versus 69.3% in CD9 negative tumours; P=0.99) and overall survival of patients (54.0% in CD9 positive- versus 58.1% in CD9 negative tumours; P=0.90) with CD9 expressing tumours to those with reduced CD9 expression. In conclusion our findings suggest that in contrast to solid tumours, CD9 is unlikely to provide any additional prognostic information for clinical purposes in osteosarcoma patients. [Copyright &y& Elsevier]

Objective: CD9 is a member of the tetra-membrane-spanning glycoprotein family called tetraspanin. CD9 suppresses breeding and motion in some types of cancer cells. At present, the expression of CD9 in the salivary gland has not yet been elucidated. Methods: We examined the expression of CD9 not only in the normal salivary glands of human embryo and adults but also in the parotid gland tumors using immunohistochemical staining. Results: CD9 was not detected in embryos at 18 weeks of gestation, but was observed at 24 weeks in the salivary gland. CD9 was constantly detected in the adult normal parotid gland. In benign parotid gland tumors, CD9 was present in the 11 of 16 pleomorphic adenomas, every Warthin tumors (18/18) and basal cell adenoma (1/1). In contrast, positive staining for CD9 in malignant parotid tumors was observed in only the case of mucoepidermoid carcinomas. Neither acinic cell carcinomas or adenoid cystic carcinomas did show positive reaction in examined cases. The localization of CD9 was also observed in intercalated duct cells. Conclusion: There was a statistically significant reduced expression of CD9 in malignant parotid gland tumors as compared to benign parotid gland tumors (P=0.003). [Copyright &y& Elsevier]

[Display omitted] • Slc44a2 is required for strong adhesion of cultured lung mesenchymal cells. • Absent or reduced Slc44a2 diminishes CD9 membrane foci in mesenchymal cells. • Loss of Slc44a2 causes tight cytoplasmic clustering of CD81 in mesenchymal cells. • Loss of Slc44a2 causes redistribution of N-cadherin in mesenchymal cells. • Mesenchymal cells with absent or reduced Slc44a2 proliferate more rapidly. Slc44a2 is reported to interact with tetraspanins CD9 and CD81. To investigate how Slc44a2 affects adhesion protein expression, cells from wild-type (WT) Slc44a2+/+ , heterozygous (HET) Slc44a2 +/-, and knockout (KO) Slc44a2- /- mice were cultured from lung tissue. The cultured cells expressed vimentin, N-cadherin, p120 catenin, beta-catenin, actin, CD9, and CD81, but not E-cadherin. Vimentin expression with lack of E-cadherin indicated that the cultured cells were of mesenchymal origin. Slc44a2 KO cells and HET cells demonstrated lower adherence and faster proliferation than the WT cells. All three groups displayed dramatically altered intracellular distribution of N-cadherin, CD9, and CD81. The CD9 membrane foci observed in WT cell membranes were less frequent and diminished in size in HET cells and KO cells. N-cadherin was dispersed throughout both the cytoplasm and membrane in WT cells, with similar yet weaker distribution in HET cells; however, in KO cells, N-cadherin was densely aggregated in the perinuclear cytoplasm. CD81 had a distribution pattern in WT, HET, and KO cells similar to that of N-cadherin with dense cytoplasmic clusters in the cells. KO cells also exhibited reduced filamentous actin as compared to WT cells. These results suggest that Slc44a2 is necessary for proper cellular localization of adhesion proteins and growth regulation that may be related to altered adhesion signals. [ABSTRACT FROM AUTHOR]

Tubo-ovarian high-grade serous carcinoma (HGSC) is unresponsive to immune checkpoint blockade despite significant frequencies of exhausted T cells. Here we apply mass cytometry and uncover decidual-like natural killer (dl-NK) cell subpopulations (CD56+CD9+CXCR3+KIR+CD3−CD16−) in newly diagnosed HGSC samples that correlate with both tumor and transitioning epithelial-mesenchymal cell abundance. We show different combinatorial expression patterns of ligands for activating and inhibitory NK receptors within three HGSC tumor compartments: epithelial (E), transitioning epithelial-mesenchymal (EV), and mesenchymal (vimentin expressing [V]), with a more inhibitory ligand phenotype in V cells. In cocultures, NK-92 natural killer cells acquire CD9 from HGSC tumor cells by trogocytosis, resulting in reduced anti-tumor cytokine production and cytotoxicity. Cytotoxicity in these cocultures is restored with a CD9-blocking antibody or CD9 CRISPR knockout, thereby identifying mechanisms of immune suppression in HGSC. CD9 is widely expressed in HGSC tumors and so represents an important new therapeutic target with immediate relevance for NK immunotherapy. [Display omitted] • Decidual-like NK cells correlate with tumor cell abundance in tubo-ovarian HGSC • Combinatorial NK receptor ligand expression levels differ across tumor compartments • NK cells acquire CD9 from HGSC tumor cells via trogocytosis • CD9 suppresses anti-tumor cytokine production and cytotoxicity in NK-92 cells In their mass cytometry study of newly diagnosed tubo-ovarian HGSC, Gonzalez et al. identify decidual-like NK cells that correlate with tumor cell abundance. CD9 distinguishes decidual NK cells from other NK cell phenotypes. In coculture, CD9 trogocytosis from ovarian tumor to NK cells confers NK cells with immune-suppressive properties. [ABSTRACT FROM AUTHOR]

In this work, we report on two novel monoclonal antibodies, specific for porcine CD9. CD9 is a tetraspanin that is expressed on a wide variety of cells. We phenotyped porcine immune cell subsets and found that CD9 was expressed on all monocytes as well as a subset of B cells. CD9 was variably expressed on T cells, with CD4 T cells containing the highest frequency of CD9+ cells. CD9 expression positively correlated with the frequency of central memory CD4 T cells in ex vivo PBMC. Therefore, we proceeded to explore CD9 as a marker of T cell function. Here we observed that CD9 was expressed on the vast majority of long-lived influenza A virus-specific effector cells that retained the capacity for cytokine production in response to in vitro recall antigen. Therefore, the new antibodies enable the detection of a cell surface molecule with functional relevance to T cells. Considering the importance of CD9 in membrane remodelling across many cell types, they will also benefit the wider field of swine biomedical research. • Two new monoclonal antibody clones (VIV–3B3 and VIV-2E12) are specific for porcine CD9. • Porcine CD9 is expressed on all monocytes and is variably expressed on lymphocytes. • The frequency of CD9+ CD4 T cells correlates with central memory CD4 T cells. • Long-lived T cells which respond to influenza A virus recall antigen express CD9. [ABSTRACT FROM AUTHOR]

Senescent cells drive atherosclerosis at all stages and contribute to cardiovascular disease. However, the markers in these senescent aortic plaques have not been well studied, creating a huge obstacle in the exploration of a precise and efficient system for atherosclerosis treatment. Recently, CD9 has been found to induce cellular senescence and aggravated atherosclerotic plaque formation in apolipoprotein E knockout (ApoE −/− ) mice. In the present study, this result has been leveraged to develop CD9 antibody-modified, hyaluronic acid-coated mesoporous silica nanoparticles with a hyaluronidase-responsive drug release profile. In in vitro models of senescent foamy macrophages and senescent endothelial cells stimulated with oxidized high-density-lipoprotein, the CD9 antibody-modified mesoporous silica nanoparticles exhibit high cellular uptake; reduce the reactive oxygen species level, high-density lipoprotein oxidation, and production of TNF-α and IL-6; and attenuate the senescence process, contributing to improved cell viability. In vivo experiment demonstrated that these nanoparticles can successfully target the senescent lesion areas, deliver the anti-senescence drug rosuvastatin to the senescent atherosclerotic plaques (mainly endothelial cells and macrophages), and alleviate the progression of atherosclerosis in ApoE −/− mice. By providing deep insight regarding the markers in senescent atherosclerotic plaque and developing a nano-system targeting this lesion area, the study proposes a novel and an accurate therapeutic approach for mitigating atherosclerosis through senescent cell clearance. [ABSTRACT FROM AUTHOR]

Lymphoblastic lymphoma (LBL) is a clinically aggressive disease, representing approximately 2% of all non-Hodgkin lymphoma cases. In the oral and maxillofacial (OMF) region, approximately 39 cases, diagnosed as LBL, acute lymphoblastic leukemia (ALL) or ALL/LBL, have been reported to date. Noteworthy, the CD9 expression, which indicates a poor outcome in ALL, has not been reported in LBL and lymphoblastic neoplasms of the OMF region. Herein, we report an additional maxillary intraosseous B-cell LBL, affecting a 14-year-old girl, which also showed positivity for CD9, Bcl-6 and MUM1/IRF4. Aiming at diagnostic and prognostic criteria, further studies focusing CD9 expression in LBL is recommended. [ABSTRACT FROM AUTHOR]

During keratinocyte stratification and wound healing, keratinocytes undergo a switch between differentiation and motility. However, limited knowledge exists on the mechanisms of the switch. We have previously demonstrated that the expression of CD9 was changed in different wound stages and involved in the regulation of keratinocyte migration. In this study, we showed that CD9 expression was increased in both human and mouse keratinocytes undergoing differentiation. CD9 overexpression in keratinocytes stimulated terminal differentiation and reduced cell motility. CD9 silencing inhibited calcium-induced keratinocyte differentiation and increased cell motility. Furthermore, CD9 overexpression recruited E-cadherin to the plasma membrane and subsequently activated PI3K/Akt signaling, while CD9 knockdown inhibited the recruitment of E-cadherin to the plasma membrane and PI3K/Akt activation. Importantly, silencing E-cadherin expression or inhibiting PI3K/Akt signaling reversed CD9 overexpression-induced differentiation and -reduced motility. These results demonstrate that CD9 acts as an important node that regulates keratinocyte differentiation and motility. The recruitment of E-cadherin to the plasma membrane and activation of the PI3K/Akt signaling pathway mediated by CD9 play an important role in these processes. • CD9 expression is increased in keratinocytes undergoing differentiation. • CD9 acts as an important node that regulates keratinocyte differentiation and motility. • CD9 recruits E-cadherin to the plasma membrane and activates PI3K/Akt signaling. • E-cadherin/PI3K/Akt pathway is involved in CD9-regulated keratinocyte differentiation and motility. [ABSTRACT FROM AUTHOR]