Human TMEM2 is not a catalytic hyaluronidase, but a regulator of hyaluronan metabolism via HYBID (KIAA1199/CEMIP) and HAS2 expression.

Cutaneous hyaluronan (HA) is depolymerized to intermediate sizes in the extracellular matrix, and further fragmented in the regional lymph nodes. Previously, we showed that the HA-binding protein involved in HA depolymerization (HYBID), also known as KIAA1199/CEMIP, is responsible for the first step of HA depolymerization. Recently, mouse transmembrane 2 (mTMEM2) with high structural similarity to HYBID was proposed to be a membrane-bound hyaluronidase. However, we showed that the knockdown of human TMEM2 (hTMEM2) conversely promoted HA depolymerization in normal human dermal fibroblasts (NHDFs). Therefore, we examined the HA-degrading activity and function of hTMEM2 using HEK293T cells. We found that human HYBID and mTMEM2, but not hTMEM2, degraded extracellular HA, indicating that hTMEM2 does not function as a catalytic hyaluronidase. Analysis of the HA-degrading activity of chimeric TMEM2 in HEK293T cells suggested the importance of the mouse GG domain. Therefore, we focused on the amino acid residues that are conserved in active mouse and human HYBID and mTMEM2 but are substituted in hTMEM2. The HA-degrading activity of mTMEM2 was abolished when its His248 and Ala303 were simultaneously replaced by the corresponding residues of inactive hTMEM2 (Asn248 and Phe303). In NHDFs, enhancement of hTMEM2 expression by proinflammatory cytokines decreased HYBID expression and increased hyaluronan synthase 2-dependent HA production. The effects of proinflammatory cytokines were abrogated by hTMEM2 knockdown. A decreased HYBID expression by interleukin-1ß and transforming growth factor-ß was canceled by hTMEM2 knockdown. In conclusion, these results indicate that hTMEM2 is not a catalytic hyaluronidase, but a regulator of HA metabolism.

ALKBH5 regulates paclitaxel resistance in NSCLC via inhibiting CEMIP-mediated EMT.

N6-methyladenosine (m6A) is the most prevalent mRNA modification, and it is verified to be closely correlated with cancer occurrence and progression. The m6A demethylase ALKBH5 (alkB homolog 5) is dysregulated in various cancers. However, the role and underlying mechanism of ALKBH5 in the pathogenesis and especially the chemo-resistance of non-small cell lung cancer (NSCLC) is poorly elucidated. The current study shows that ALKBH5 expression is reduced in paclitaxel (PTX) resistant NSCLC cells and down-regulation of ALKBH5 usually implies poor prognosis of NSCLC patients. Over-expression of ALKBH5 in PTX-resistant cells can suppress cell proliferation and enhance chemo-sensitivity, while knockdown of ALKBH5 exerts the opposite effect, which further supports the tumor suppressive role of ALKBH5. Over-expression of ALKBH5 can also reverse the epithelial-mesenchymal transition (EMT) process in PTX-resistant cancer cells. Mechanistically, data from RNA-seq, real-time PCR and western blotting indicate that CEMIP (cell migration inducing hyaluronidase 1), also known as KIAA1199, may be the downstream target of ALKBH5. Furthermore, ALKBH5 negatively regulates the CEMIP level by reducing the stability of CEMIP mRNA. Collectively, the current data demonstrate that the ALKBH5/CEMIP axis modulates the EMT process in NSCLC, which in turn regulates the chemo-sensitivity of cancer cells to PTX.

CCDC88C, an O-GalNAc glycosylation substrate of GALNT6, drives breast cancer metastasis by promoting c-JUN-mediated CEMIP transcription.

Coiled-coil domain containing 88C (CCDC88C) is a component of non-canonical Wnt signaling, and its dysregulation causes colorectal cancer metastasis. Dysregulated expression of CCDC88C was observed in lymph node metastatic tumor tissues of breast cancer. However, the role of CCDC88C in breast cancer metastasis remains unclear. To address this, the stable BT549 and SKBR3 cell lines with CCDC88C overexpression or knockdown were developed. Loss/gain-of-function experiments suggested that CCDC88C drove breast cancer cell motility in vitro and lung and liver metastasis in vivo. We found that CCDC88C led to c-JUN-induced transcription activation. Overlapping genes were identified from the genes modulated by CCDC88C and c-JUN. CEMIP, one of these overlapping genes, has been confirmed to confer breast cancer metastasis. We found that CCDC88C regulated CEMIP mRNA levels via c-JUN and it exerted pro-metastatic capabilities in a CEMIP-dependent manner. Moreover, we identified the CCDC88C as a substrate of polypeptide N-acetylgalactosaminyltransferase 6 (GALNT6). GALNT6 was positively correlated with CCDC88C protein abundance in the normal breast and breast cancer tissues, indicating that GALNT6 might be associated with expression patterns of CCDC88C in breast cancer. Our data demonstrated that GALNT6 maintained CCDC88C stability by promoting its O-linked glycosylation, and the modification was critical for the pro-metastatic potential of CCDC88C. CCDC88C also could mediate the pro-metastatic potential of GALNT6 in breast cancer. Collectively, our findings uncover that CCDC88C may increase the risk of breast cancer metastasis and elucidate the underlying molecular mechanisms.

Naked mole-rat TMEM2 lacks physiological hyaluronan-degrading activity.

Mouse transmembrane protein 2 (mTMEM2) has been identified as a hyaluronidase, which has extracellularly G8 and GG domains and PbH1 repeats; however, our previously study showed that human TMEM2 (hTMEM2) is not a catalytic hyaluronidase due to the absence of the critical amino acid residues (His248/Ala303) in the GG domain. Naked mole-rats (NMRs) accumulate abundant high-molecular weight hyaluronan (HA) in their tissues, suggesting decreased HA degradation. Therefore, we aimed to evaluate the HA-degrading activity of NMR TMEM2 (nmrTMEM2) and compare it with those of mTMEM2 and hTMEM2. The amino acid residues of nmrTMEM2 (Asn247/Val302) are similar to Asn248/Phe303 of hTMEM2, and nmrTMEM2-expressing HEK293T cells showed negligible activity. We confirmed the significance of these amino acid residues using an inactive chimeric TMEM2 with the human GG domain, which acquired catalytic activity when Asn248/Phe303 was substituted with His248/Ala303. Semi-quantitative comparison of the activities of the membrane-fractions derived from m/h/nmrTMEM2-expressing HEK293T cells revealed that at least 20- and 14-fold higher amounts of nmr/hTMEM2 were required to degrade HA to the same extent as by mTMEM2. Thus, unlike mTMEM2, nmrTMEM2 is not a physiological hyaluronidase. The inability of nmrTMEM2 to degrade HA might partially account for the high-molecular-weight HA accumulation in NMR tissues.

Adaptor protein CEMIP reduces the chemosensitivity of small cell lung cancer via activation of an SRC-YAP oncogenic module.

Small cell lung cancer (SCLC) is a recalcitrant malignancy with dismal prognosis due to rapid relapse after an initial treatment response. More effective treatments for SCLC are desperately needed. Our previous studies showed that cell migration-inducing hyaluronan binding protein (CEMIP) functionally promotes SCLC cell proliferation and metastasis. In this study, we investigated whether and how CEMIP regulates the chemosensitivity of SCLC. Through the GDSC database, we found that CEMIP expression levels were positively correlated with the IC50 values of several commonly used chemotherapeutic drugs in SCLC cells (cisplatin, gemcitabine, 5-fluorouracil and cyclophosphamide). We demonstrated that overexpression or knockdown of CEMIP in SCLC cells resulted in a notable increase or reduction in the IC50 value of cisplatin or etoposide, respectively. We further revealed that CEMIP functions as an adaptor protein in SCLC cells to interact with SRC and YAP through the 1-177 aa domain and 820-1361 aa domain, respectively, allowing the autophosphorylation of Y416 and activation of SRC, thus facilitating the interaction between YAP and activated SRC, and resulting in increased phosphorylation of Y357, protein stability, nuclear accumulation and transcriptional activation of YAP. Overexpressing SRC or YAP counteracted the CEMIP knockdown-mediated increase in the sensitivity of SCLC cells to cisplatin and etoposide. The combination of the SRC inhibitor dasatinib or the YAP inhibitor verteporfin and cisplatin/etoposide (EP regimen) displayed excellent synergistic antitumor effects on SCLC both in vitro and in vivo. This study demonstrated that targeted therapy against the CEMIP/SRC/YAP complex is a potential strategy for SCLC and provides a rationale for the development of future clinical trials with translational prospects.

Expression and significance of CEMIP and CYP11B2 in serum in women with foetal growth restriction.

BACKGROUND: Foetal growth restriction (FGR) occurs when a foetus fails to reach its growth potential. This observational study assessed the expression and significance of cell migration-including protein (CEMIP) and aldosterone synthase (CYP11B2) in the serum of pregnant women with FGR. METHODS: 40 singleton FGR-suffered pregnant women, as well as 40 normal singleton pregnant women, were enrolled. The expression of CEMIP and CYP11B2 in serum was detected in early pregnancy. The correlations between parameters were evaluated. The predictive variables for FGR were determined. The diagnostic value of CEMIP and CYP11B2 for FGR was analysed. RESULTS: CEMIP and CYP11B2 mRNA expression in the serum of pregnant women with FGR decreased (both P < 0.001). CEMIP (95%CI: 0.802-0.921, P < 0.001) and CYP11B2 (95%CI: 0.795-0.907, P < 0.001) mRNA expression in serum and soluble fms like tyrosine kinase-1 (sFLT1)/placental growth factor (PlGF) ratio (95%CI: 0.866-0.974, P < 0.001) were independent predictors of FGR, and CEMIP (r = -0.578, P = 0.001) and CYP11B2 (r = -0.602, P < 0.001) mRNA expression in serum were negatively correlated with sFLT1/PlGF ratio. CEMIP (AUC = 0.741) and CYP11B2 (AUC = 0.764) mRNA expression in serum had good diagnostic value for FGR. CONCLUSION: The expression of CEMIP and CYP11B2 is reduced in the serum of pregnant women with FGR and may become new diagnostic markers for FGR.

Foetal growth restriction is the inability of the foetus to reach its growth potential in the uterus due to various factors. This study aimed to investigate the expression and significance of cell migration-including protein and aldosterone synthase in serum of pregnant women with foetal growth restriction. In our study, we found that the expression of cell migration-including protein and aldosterone synthase in serum of pregnant women with foetal growth restriction were decreased. Cell migration-including protein and aldosterone synthase expression was negatively correlated with soluble fms like tyrosine kinase-1/placental growth factor ratio. In addition, the study also found that cell migration-including protein and aldosterone synthase expression in serum had good diagnostic value for foetal growth restriction.

CEMIP (KIAA1199) regulates inflammation, hyperplasia and fibrosis in osteoarthritis synovial membrane.

Osteoarthritis (OA) synovial membrane is mainly characterized by low-grade inflammation, hyperplasia with increased cell proliferation and fibrosis. We previously underscored a critical role for CEMIP in fibrosis of OA cartilage. However, its role in OA synovial membrane remains unknown. An in vitro model with fibroblast-like synoviocytes from OA patients and an in vivo model with collagenase-induced OA mice were used to evaluate CEMIP-silencing effects on inflammation, hyperplasia and fibrosis. Our results showed that i. CEMIP expression was increased in human and mouse inflamed synovial membrane; ii. CEMIP regulated the inflammatory response pathway and inflammatory cytokines production in vitro and in vivo; iii. CEMIP induced epithelial to mesenchymal transition pathway and fibrotic markers in vitro and in vivo; iv. CEMIP increased cell proliferation and synovial hyperplasia; v. CEMIP expression was increased by inflammatory cytokines and by TGF-ß signaling; vi. anti-fibrotic drugs decreased CEMIP expression. All these findings highlighted the central role of CEMIP in OA synovial membrane development and underscored that targeting CEMIP could be a new therapeutic approach.

CEMIP promotes extracellular matrix-detached prostate cancer cell survival by inhibiting ferroptosis.

Cells detached from the extracellular matrix (ECM) can trigger different modes of cell death, and the survival of ECM-detached cells is one of the prerequisites for the metastatic cascade. Ferroptosis, a form of iron-dependent programmed cell death, has recently been found to be involved in matrix-detached cancer cells. However, the molecular mechanisms by which ECM-detached cells escape ferroptosis are not fully understood. Here, we observed that cell migration-inducing protein (CEMIP) upregulation facilitates ferroptosis resistance during ECM detachment by promoting cystine uptake in prostate cancer (PCa) cells. Meanwhile, silencing CEMIP causes it to lose its ability to promote cystine uptake and inhibit ferroptosis. Mechanistically, the interaction of CEMIP with inositol 1,4,5-trisphosphate receptor type 3 (ITPR3) modulates calcium ion (Ca2+ ) leakage from the endoplasmic reticulum, activating calcium/calmodulin-dependent protein kinase II (CaMKII), which further facilitates nuclear factor erythroid 2-related factor 2 (NRF2) phosphorylation and nuclear localization, leading to elevated transcription of solute carrier family 7 member 11 (SLC7A11), a glutamate/cystine antiporter, in PCa cells. Our findings delineate a novel role of CEMIP in ferroptosis resistance during ECM detachment and provide new insights into therapeutic strategies for metastatic PCa.

Loss of REST in breast cancer promotes tumor progression through estrogen sensitization, MMP24 and CEMIP overexpression.

BACKGROUND: Breast cancer is the most common malignancy in women, and is both pathologically and genetically heterogeneous, making early detection and treatment difficult. A subset of breast cancers express normal levels of REST (repressor element 1 silencing transcription factor) mRNA but lack functional REST protein. Loss of REST function is seen in ~ 20% of breast cancers and is associated with a more aggressive phenotype and poor prognosis. Despite the frequent loss of REST, little is known about the role of REST in the molecular pathogenesis of breast cancer. METHODS: TCGA data was analyzed for the expression of REST target genes in breast cancer patient samples. We then utilized gene knockdown in MCF-7 cells in the presence or absence of steroid hormones estrogen and/ progesterone followed by RNA sequencing, as well as chromatin immunoprecipitation and PCR in an attempt to understand the tumor suppressor role of REST in breast cancer. RESULTS: We show that REST directly regulates CEMIP (cell migration-inducing and hyaluronan-binding protein, KIAA1199) and MMP24 (matrix metallopeptidase 24), genes known to have roles in invasion and metastasis. REST knockdown in breast cancer cells leads to significant upregulation of CEMIP and MMP24. In addition, we found REST binds to RE-1 sites (repressor element-1) within the genes and influences their transcription. Furthermore, we found that the estrogen receptor (ESR1) signaling pathway is activated in the absence of REST, regardless of hormone treatment. CONCLUSIONS: We demonstrate a critical role for the loss of REST in aggressive breast cancer pathogenesis and provide evidence for REST as an important diagnostic marker for personalized treatment plans.

CEMIP as a potential biomarker and therapeutic target for breast cancer patients.

Purpose: We aimed to evaluate whether CEMIP plays any role in the survival outcome of breast cancer (BC) patients, as well as to explore the regulatory mechanism of CEMIP in BC. Methods: We evaluated the expression and prognostic effect of CEMIP in BC patients using the Oncomine, GEPIA, UALCAN, and Kaplan-Meier plotter databases. Additionally, we detected CEMIP mRNA and protein levels in BC and normal tissues via PCR and western blotting analyses. Through immunochemistry analysis, we quantified CEMIP expression in 233 samples from BC patients. We then analyzed the link between the survival outcomes and CEMIP expression based on these clinical samples. Furthermore, we explored the immune-related molecules regulated by CEMIP and its coexpressed genes using the STRING database. Results: CEMIP expression was higher in BC tissues than in normal tissues. Patients with high CEMIP mRNA levels had a worse survival outcome. Similarly, patients expressing CEMIP had significantly shorter overall survival and disease-free survival than those not expressing the protein (P < 0.01). Some lymphocytes, immune inhibitors, immune stimulators, MHC molecules, chemokines, and chemokine receptors can be regulated by CEMIP, and CEMIP and its coexpressed genes can participate in the hyaluronan biosynthetic process, hyaluronan catabolic process, and other related biological processes in the progression of BC. Conclusion: Compared to normal tissues, BC tissues had higher number of CEMIP transcripts. CEMIP expression was associated with an adverse prognosis. CEMIP and its coexpressed genes can participate in the progression of BC. Therefore, CEMIP may be a potential biomarker for the treatment of BC patients.

circ-BPTF serves as a miR-486-5p sponge to regulate CEMIP and promotes hypoxic pulmonary arterial smooth muscle cell proliferation in COPD.

Hypoxia plays a crucial role in pulmonary vascular remodelling at the early stage of chronic obstructive pulmonary disease (COPD). Circle RNA (circRNA) has been identified to play a critical role in multiple diseases. However, the role of circRNAs in pulmonary vascular remodelling in COPD remains unclear. In this study, we aim to investigate the role of circRNAs in pulmonary arterial smooth muscle cell proliferation and pulmonary vascular remodelling in COPD. COPD patients show lower partial pressure of arterial oxygen and pulmonary arterial remodeling as compared with controls. circRNA microarray and real-time PCR analyses show significantly higher level of circ-BPTF and lower miR-486-5p level in the pulmonary arteries of COPD patients as compared with controls. Hypoxia suppresses miR-486-5p expression but promotes expressions of circ-BPTF and cell migration inducing protein (CEMIP) in human pulmonary arterial smooth muscle cells (PASMCs) in vitro. Loss- and gain-of-function experiments show that circ-BPTF promotes PASMC proliferation in vitro. Moreover, luciferase reporter assay results indicate that circ-BPTF regulates PASMC proliferation by acting as an miR-486-5p sponge. CEMIP is identified as a candidate target gene of miR-486-5p by luciferase reporter assay. Overall, our study shows that circ-BPTF serves as a miR-486-5p sponge to regulate CEMIP and promote hypoxic PASMC proliferation in pulmonary vascular remodelling in COPD.

Possible Repositioning of an Oral Anti-Osteoporotic Drug, Ipriflavone, for Treatment of Inflammatory Arthritis via Inhibitory Activity of KIAA1199, a Novel Potent Hyaluronidase.

KIAA1199 has a strong hyaluronidase activity in inflammatory arthritis. This study aimed to identify a drug that could reduce KIAA1199 activity and clarify its effects on inflammatory arthritis. Rat chondrosarcoma (RCS) cells were strongly stained with Alcian blue (AB). Its stainability was reduced in RCS cells, which were over-expressed with the KIAA1199 gene (RCS-KIAA). We screened the drugs that restore the AB stainability in RCS-KIAA. The effects of the drug were evaluated by particle exclusion assay, HA ELISA, RT-PCR, and Western blotting. We further evaluated the HA accumulation and the MMP1 and three expressions in fibroblast-like synoviocytes (FLS). In vivo, the effects of the drug on symptoms and serum concentration of HA in a collagen-induced arthritis mouse were evaluated. Ipriflavone was identified to restore AB stainability at 23%. Extracellular matrix formation was significantly increased in a dose-dependent manner (p = 0.006). Ipriflavone increased the HA accumulation and suppressed the MMP1 and MMP3 expression on TNF-α stimulated FLS. In vivo, Ipriflavone significantly improved the symptoms and reduced the serum concentrations of HA. Conclusions: We identified Ipriflavone, which has inhibitory effects on KIAA1199 activity. Ipriflavone may be a therapeutic candidate based on its reduction of KIAA1199 activity in inflammatory arthritis.

MiR-148a-3p targets CEMIP to suppress the genesis of gastric cancer cells.

BACKGROUND: Gastric cancer is the sixth common malignancy worldwide. Dysregulation of Cell Migration Inducing Hyaluronidase 1 (CEMIP) gene and microRNA-148a -3p (miR-148a-3p) expressions has been found in gastric cancer genesis. However, the underlying molecular mechanism in gastric cancer needs further investigation. METHODS: The expression of gastric cancer tissues' and cells' CEMIP and miR-148a-3p were examined by RT-qPCR. The interaction between miR-148a-3p and CEMIP was verified by luciferase activity detection. Cell viability, proliferation, adhesion, and apoptosis in gastric cancer GTL-16 and AGS cells were analyzed by CCK8, BrdU, cell adhesion, and FITC assay. RESULTS: CEMIP expression was significantly elevated, but the miR-148a-3p level was downregulated in gastric cancer tissues and cell lines. Overexpression of CEMIP accelerated cell viability, proliferation, and adhesion, but attenuated cell apoptosis of gastric cancer cells. In addition, upregulation of miR-148a-3p repressed the development of gastric cancer in vitro. Moreover, miR-148a-3p suppressed gastric cancer tumorigenesis by inhibiting the expression of CEMIP. CONCLUSION: The study clarified that miR-148a-3p suppressed gastric cancer tumorigenesis by inhibiting CEMIP, which may be effective targets for the clinical treatment of gastric cancer.

Pro-inflammatory cytokines suppress HYBID (hyaluronan (HA) -binding protein involved in HA depolymerization/KIAA1199/CEMIP) -mediated HA metabolism in human skin fibroblasts.

In the skin, the metabolism of hyaluronan (HA) is highly regulated. Aging leads to chronic low-grade inflammation, which is characterized by elevated levels of pro-inflammatory cytokines; however, the relationship between inflammation and HA metabolism is not clear. Herein, we investigated the effects of a mixture of pro-inflammatory cytokines containing TNF-α, IL-1ß, and IL-6 on HA metabolism in human skin fibroblasts. Treatment with the cytokine mixture for 24 h suppressed HA depolymerization via downregulation of HYBID (HA-binding protein involved in HA depolymerization/KIAA1199/CEMIP) and promoted HA synthesis via upregulation of HAS2 in human skin fibroblasts. Moreover, HAS2-dependent HA synthesis was driven mainly by IL-1ß with partial contribution from TNF-α. Transmembrane protein 2 (TMEM2/CEMIP2), which was previously reported as a candidate hyaluronidase, was upregulated by the cytokine mixture, suggesting that TMEM2 might not function as a hyaluronidase in human skin fibroblasts. Furthermore, the effects of the cytokine mixture on HA metabolism were observed in fibroblasts after 8 days of treatment with cytokines during three passages. Thus, we have shown that HYBID-mediated HA metabolism is negatively regulated by the pro-inflammatory cytokine mixture, providing novel insights into the relationship between inflammation and HA metabolism in the skin.

Cell migration inducing hyaluronidase 1 (CEMIP) activates STAT3 pathway to facilitate cell proliferation and migration in breast cancer.

PURPOSE: This paper aims to assess the role of CEMIP in human breast cancer, and explore the potential mechanisms of CEMIP in the progression of breast cancer. METHODS: We examined the expression levels of CEMIP in breast cancer tissues and cell lines by quantitative PCR and immunohistochemical assays. The effects of CEMIP on the proliferation, migration and invasion of breast cancer cells were determined through colony formation assay, flow cytometry (FCM) assay, wound healing assay and transwell assay, respectively. Additionally, the downstream targets of CEMIP were examined by Immunoblot assays. RESULTS: CEMIP expression was upregulated in both breast cancer tissues and cell lines. Patients with higher CEMIP expression displayed shorter survival time than those with lower expression. In addition, CEMIP knockdown inhibited breast cancer cell proliferation, migration, and invasion in vitro. Our data further confirmed that CEMIP promoted the proliferation and migration of breast cancer cells via GRP78-STAT3 axis. CONCLUSION: Our data demonstrated the role of CEMIP in breast cancer was associated with STAT3 signaling pathway. Therefore, CEMIP might act as a possible therapeutic target for breast cancer.

CEMIP regulates the proliferation and migration of vascular smooth muscle cells in atherosclerosis through the WNT-beta-catenin signaling pathway.

In this study we investigated the regulatory role of cell-migration-inducing and hyaluronan-binding protein (CEMIP) in the proliferation and migration of vascular smooth muscle cells (VSMCs). The mRNA and protein levels of CEMIP were upregulated in the plasma samples from patients with atherosclerosis, and in VSMCs stimulated with platelet-derived growth factor-BB (PDGF-BB), compared with plasma from healthy subjects and untreated VSMCs. Silencing CEMIP suppressed PDGF-BB-induced cell migration and proliferation in VSMCs, as determined using a Cell Counting Kit-8 assays, 5-ethynyl-2'-deocyuridine (EDU) assays, flow cytometry, wound healing assays, and Transwell assays. Overexpression of CEMIP promoted the proliferation and migration of VSMCs via activation of the Wnt-ß-catenin signaling pathway and the upregulation of its target genes, including matrix metalloproteinase-2, matrix metalloproteinase-7, cyclin D1, and c-myc, whereas CEMIP deficiency showed the opposite effects. The knockdown of CEMIP in ApoE-/- mice by intravenous injection of lentiviral vector expressing si-CEMIP protected against high-fat-diet-induced atherosclerosis, as shown by the reduced aortic lesion areas, aortic sinus lesion areas, and the concentration of blood lipids compared with mice normally expressing CEMIP. These results demonstrated that CEMIP regulates the proliferation and migration of VSMCs in atherosclerosis by activating the WNT-ß-catenin signaling pathway, which suggests the therapeutic potential of CEMIP for the management of atherosclerosis.

Induction of CEMIP in Chondrocytes by Inflammatory Cytokines: Underlying Mechanisms and Potential Involvement in Osteoarthritis.

In patients with osteoarthritis (OA), there is a decrease in both the concentration and molecular size of hyaluronan (HA) in the synovial fluid and cartilage. Cell migration-inducing hyaluronidase 1 (CEMIP), also known as hyaluronan (HA)-binding protein involved in HA depolymerization (HYBID), was recently reported as an HA depolymerization-related molecule expressed in the cartilage of patients with OA. However, the underlying mechanism of CEMIP regulation is not well understood. We found that CEMIP expression was transiently increased by interleukine-1ß (IL-1ß) stimulation in chondrocytic cells. We also observed that ERK activation and NF-κB nuclear translocation were involved in the induction of CEMIP by IL-1ß. In addition, both administration of HA and mechanical strain attenuated the CEMIP induction in IL-1ß-stimulated chondrocytes. In conclusion, we clarified the regulatory mechanism of CEMIP in chondrocytes by inflammatory cytokines and suggested the potential involvement in osteoarthritis development.

Tmem2 restricts atrioventricular canal differentiation by regulating degradation of hyaluronic acid.

BACKGROUND: Atrioventricular valve development relies upon the precisely defined dimensions of the atrioventricular canal (AVC). Current models suggest that Wnt signaling plays an important role atop a pathway that promotes AVC development. The factors that confine AVC differentiation to the appropriate location, however, are less well understood. RESULTS: Transmembrane protein 2 (Tmem2) is a key player in restricting AVC differentiation: in zebrafish, tmem2 mutants display an expansion of AVC characteristics, but the molecular mechanism of Tmem2 function in this context remains unclear. Through structure-function analysis, we demonstrate that the extracellular portion of Tmem2 is crucial for its role in restricting AVC boundaries. Importantly, the Tmem2 ectodomain contains regions implicated in the depolymerization of hyaluronic acid (HA). We find that tmem2 mutant hearts exhibit excess HA deposition alongside broadened distribution of Wnt signaling. Moreover, addition of ectopic hyaluronidase can restore the restriction of AVC differentiation in tmem2 mutants. Finally, we show that alteration of a residue important for HA depolymerization impairs the efficacy of Tmem2 function during AVC development. CONCLUSIONS: Taken together, our data support a model in which HA degradation, regulated by Tmem2, limits the distribution of Wnt signaling and thereby confines the differentiation of the AVC.

Role of HYBID (Hyaluronan Binding Protein Involved in Hyaluronan Depolymerization), Alias KIAA1199/CEMIP, in Hyaluronan Degradation in Normal and Photoaged Skin.

Photoaged skin is characterized clinically by apparent manifestations such as wrinkles and sagging, and histologically by an accumulation of abnormal elastin and a severe loss of collagen fibers in the dermis. Quantitative and qualitative alterations in elastin and collagens are considered to be responsible for the formation of wrinkles and sagging. However, since the integrity of elastin and collagen fibers in the dermis is maintained by their interactions with hyaluronan (HA) and a proteoglycan network structure, HA degradation may be the initial process, prior to the breakdown of the fibrillary components, leading to wrinkles and sagging in photoaged skin. We have recently discovered a new HA-degrading mechanism mediated by HYBID (hyaluronan binding protein involved in hyaluronan depolymerization), alias KIAA1199/CEMIP, in human skin fibroblasts, and examined the implication of HYBID for skin photoaging. In this review, we give an overview of the characteristics of HYBID and its prospective roles in HA turnover in normal skin and excessive HA degradation in photoaged skin. In addition, we describe our data on the inhibition of HYBID activity and expression by plant extracts in skin fibroblasts; and propose novel strategies to prevent or improve photoaging symptoms, such as skin wrinkling, by inhibition of HYBID-mediated HA degradation.

A mammalian homolog of the zebrafish transmembrane protein 2 (TMEM2) is the long-sought-after cell-surface hyaluronidase.

Hyaluronan (HA) is an extremely large polysaccharide (glycosaminoglycan) involved in many cellular functions. HA catabolism is thought to involve the initial cleavage of extracellular high-molecular-weight (HMW) HA into intermediate-size HA by an extracellular or cell-surface hyaluronidase, internalization of intermediate-size HA, and complete degradation into monosaccharides in lysosomes. Despite considerable research, the identity of the hyaluronidase responsible for the initial HA cleavage in the extracellular space remains elusive. HYAL1 and HYAL2 have properties more consistent with lysosomal hyaluronidases, whereas CEMIP/KIAA1199, a recently identified HA-binding molecule that has HA-degrading activity, requires the participation of the clathrin-coated pit pathway of live cells for HA degradation. Here we show that transmembrane protein 2 (TMEM2), a mammalian homolog of a protein playing a role in zebrafish endocardial cushion development, is a cell-surface hyaluronidase. Live immunostaining and surface biotinylation assays confirmed that mouse TMEM2 is expressed on the cell surface in a type II transmembrane topology. TMEM2 degraded HMW-HA into ∼5-kDa fragments but did not cleave chondroitin sulfate or dermatan sulfate, indicating its specificity to HA. The hyaluronidase activity of TMEM2 was Ca2+-dependent; the enzyme's pH optimum is around 6-7, and unlike CEMIP/KIAA1199, TMEM2 does not require the participation of live cells for its hyaluronidase activity. Moreover, TMEM2-expressing cells could eliminate HA immobilized on a glass surface in a contact-dependent manner. Together, these data suggest that TMEM2 is the long-sought-after hyaluronidase that cleaves extracellular HMW-HA into intermediate-size fragments before internalization and degradation in the lysosome.