Laminin alpha1 chain mediated reduction of laminin alpha2 chain deficient muscular dystrophy involves integrin alpha7beta1 and dystroglycan

Transgenically introduced laminin (LN) alpha1 chain prevents muscular dystrophy in LNalpha2 chain deficient mice. We now report increased integrin alpha7Bbeta1D synthesis in dystrophic LNalpha2 chain deficient muscle. Yet, immunofluorescence demonstrated a reduced expression of integrin alpha7B subunit at the sarcolemma. Transgenic expression of LNalpha1 chain reconstituted integrin alpha7B at the sarcolemma. Expression of alpha- and beta-dystroglycan is enhanced in LNalpha2 chain deficient muscle and normalized by transgenic expression of LNalpha1 chain. We suggest that LNalpha1 chain in part ameliorates the development of LNalpha2 chain deficient muscular dystrophy by retaining the binding sites for integrin alpha7Bbeta1D and alpha-dystroglycan, respectively.     

Signaling pathway of MAPK/ERK in cell proliferation,differentiation, migration,senescence and apoptosis

Abstract

The generic mitogen-activated protein kinases (MAPK) signaling pathway is shared by four distinct cascades, including the extracellular signal-related kinases (ERK1/2), Jun amino-terminal kinases (JNK1/2/3), p38-MAPK and ERK5. Mitogen-activated protein kinases/extracellular signal-regulated kinase (MAPK/ERK) pathway is reported to be associated with the cell proliferation, differentiation, migration, senescence and apoptosis. The literatures were searched extensively and this review was performed to review the role of MAPK/ERK signaling pathway in cell proliferation, differentiation, migration, senescence and apoptosis.     

Epigallocatechin-3-gallate (EGCG) inhibits PC-3 prostate cancer cell proliferation via MEK-independent ERK1/2 activation

Epigallocatechin-3-gallate (EGCG), a tea polyphenol, inhibits the proliferation of many cancer cell lines; however, the antiproliferative mechanism(s) are not well-characterized. The objective of this study is to identify the cellular signaling mechanism(s) responsible for the antiproliferative effects of EGCG in the PC-3 prostate cancer cell line. EGCG inhibited PC-3 cell proliferation in a concentration-dependent manner with an IC(50) value of 39.0 microM, but had no effect on the proliferation of a nontumorigenic prostate epithelial cell line (RWPE-1). Treatment of PC-3 cells with EGCG (0-50 microM) resulted in time and concentration-dependent activation of the extracellular signal-regulated kinase (ERK1/2) pathway. EGCG treatment did not induce ERK1/2 activity in RWPE-1 cells. The activation of ERK1/2 by EGCG was not inhibited using PD98059, a potent inhibitor of mitogen-activated protein kinase kinase (MEK), the immediate upstream kinase responsible for ERK1/2 activation; suggesting a MEK-independent signaling mechanism. Pretreatment of PC-3 cells with a phosphoinositide-3 kinase (PI3K) inhibitor partially reduced both EGCG-induced ERK1/2 activation and the antiproliferative effects of this polyphenol. These results suggest that ERK1/2 activation via a MEK-independent, PI3-K-dependent signaling pathway is partially responsible for the antiproliferative effects of EGCG in PC-3 cells.     

Laminin isoforms and their integrin receptors in glioma cell migration and invasiveness: Evidence for a role of alpha5-laminin(s) and alpha3beta1 integrin

Glioma cell infiltration of brain tissue often occurs along the basement membrane (BM) of blood vessels. In the present study we have investigated the role of laminins, major structural components of BMs and strong promoters of cell migration. Immunohistochemical studies of glioma tumor tissue demonstrated expression of alpha2-, alpha3-, alpha4- and alpha5-, but not alpha1-, laminins by the tumor vasculature. In functional assays, alpha3 (Lm-332/laminin-5)- and alpha5 (Lm-511/laminin-10)-laminins strongly promoted migration of all glioma cell lines tested. alpha1-Laminin (Lm-111/laminin-1) displayed lower activity, whereas alpha2 (Lm-211/laminin-2)- and alpha4 (Lm-411/laminin-8)-laminins were practically inactive. Global integrin phenotyping identified alpha3beta1 as the most abundant integrin in all the glioma cell lines, and this laminin-binding integrin exclusively or largely mediate the cell migration. Moreover, pretreatment of U251 glioma cells with blocking antibodies to alpha3beta1 integrin followed by intracerebral injection into nude mice inhibited invasion of the tumor cells into the brain tissue. The cell lines secreted Lm-211, Lm-411 and Lm-511, at different ratios. The results indicate that glioma cells secrete alpha2-, alpha4- and alpha5-laminins and that alpha3- and alpha5-laminins, found in brain vasculature, selectively promote glioma cell migration. They identify alpha3beta1 as the predominant integrin and laminin receptor in glioma cells, and as a brain invasion-mediating integrin.     

Specific inhibitor of MEK-mediated cross-talk between ERK and p38 MAPK during differentiation of human osteosarcoma cells

Osteosarcoma is the most common primary malignant bone tumor, accounting for approximately 20% of all primary sarcomas in bone. Although treatment modalities have been improved over the past decades, it is still a tumor with a high mortality rate in children and young adults. Based on histological considerations, osteosarcoma arises from impaired differentiation of these immature cells into more mature types and that correction of this impairment may reduce malignancy and increase the efficiency of chemotherapy. The purpose of this study was to determine the effect of specific inhibitors of MAPK extracellular signaling-regulated kinase (ERK) kinase (MEK) and p38 on the differentiation of human osteosarcoma cell line SaOS-2 cells. We found that PD98059, a specific inhibitor of MEK, inhibited the serum-stimulated proliferation of SaOS-2 cells; whereas SB203580, a specific inhibitor of p38 MAPK, had little effect on it. SB203580 suppressed ALPase activity, gene expression of type I collagen, and expression of ALP and BMP-2 mRNAs; whereas PD98059 upregulated them dose dependently. In addition, immunoblot and immunostaining analysis revealed that phosphorylation of ERK was increased by treatment with SB203580; whereas PD98059 increased the phosphorylation of p38, which implies a seesaw-like balance between ERK and p38 phosphorylation. We suggest that osteosarcoma cell differentiation is regulated by the balance between the activities of the ERK and p38 pathways and that the MEK/ERK pathway negatively regulates osteosarcoma cell differentiation, whereas the p38 pathway does so positively. MEK inhibitor may thus be a good candidate for altering the expression of the osteosarcoma malignant phenotype.     

Laminin-3B11, a Novel Vascular-type Laminin Capable of Inducing Prominent Lamellipodial Protrusions in Microvascular Endothelial Cells

The basement membrane (BM) proteins laminins, which consist of α, β, and γ chains, support tissue structures and cellular functions. To date only α4 and α5 types of laminins have been identified in the BMs of blood vessels. Our recent study suggested the presence of novel α3B-containing laminins in vascular BMs. Here we identified and characterized the third member of vascular laminins, laminin-3B11 (Lm3B11). RT-PCR analysis showed that microvascular endothelial (MVE) cells and umbilical vein endothelial cells expressed the messages for the α3B, β1, β2, and γ1 chains. In the culture of MVE cells, α3B was associated with β1 and γ1, producing Lm3B11. Recombinant Lm3B11 was overexpressed by introducing the cDNAs of the three chains into HEK-293 cells and purified to homogeneity. Purified Lm3B11 exhibited relatively weak cell adhesion activity through both α3β1 and α6β1 integrins. Most characteristically, Lm3B11 strongly stimulated MVE cells to extend many lamellipodial protrusions. This pseudopodial branching was blocked by an inhibitor for Src or phosphatidylinositol 3-kinase. Consistently, Lm3B11 stimulated the phosphorylation of Src and Akt more strongly than other laminins, suggesting that the integrin-derived signaling is mediated by these factors. The unique activity of Lm3B11 appears to be favorable to the branching of capillaries and venules.     

ERK活化对哮喘大鼠气道重塑及CyclinD1表达的影响

目的探讨细胞外信号调节蛋白激酶（ERK）对哮喘大鼠气道重塑及CyclinD1表达的作用。方法原代培养大鼠的平滑肌细胞（ASMCs）,给予ERK激动剂表皮生长因子EGF和抑制剂PD98059干预ASMCs生长,依处理方式不同分为5组：（1）正常对照组（2）哮喘对照组;（3）E组：EGF20 ng/mL;（4）P＋E组,PD98059 10μmol/L1 h后添加EGF 20 ng/mL;（5）PD组,PD98059 10μmol/L。采用四甲基偶氮唑盐（MTT）法检测气道平滑肌细胞（ASMCs）增殖能力,流式细胞术（FCM）测定细胞周期和cyclinD1的蛋白含量,RT-PCR方法检测cyclinD1mRNA表达水平。结果（1）与哮喘对照组比较,E组ASMCs S＋G2/M期比例、吸光度A值、cyclinD1蛋白阳性表达率和cyclinD1 mRNA的A值均显著升高,PD组均显著降低（P〈0.05）。P＋E组与哮喘对照在此4项指标上比较无明显差异。（2）哮喘（对照组、E组、PD组和P＋E组）组与正常对照组,其S＋G2/M期比例、吸光度A值、cyclinD1蛋白和cyclinD1 mRNA的表达均显著增高（P〈0.05）。结论ERK活性促进哮喘大鼠ASMCs的增殖,增加cyclinD1在哮喘平滑肌细胞中的表达,导致气道重塑的形成,提示ERK可能对CyclinD1的表达具有调节作用。     

Mediation of Rac1 activation by kindlin-2: an essential function in osteoblast adhesion, spreading, and proliferation

Kindlins are focal adhesion proteins that regulate integrin signaling. Although integrin activation is critical for bone development, little is known about the expression and role of kindlins in osteoblasts. We therefore investigated the function of kindlin-2 in osteoblast adhesion, spreading, and proliferation using small interfering RNA. In MC3T3-E1 cells, only kindlin-2 is highly expressed and localizes to focal adhesion. We found that kindlin-2 was involved in integrin activation in MC3T3-E1 cells and that kindlin-2 knockdown osteoblasts resulted in diminished cell adhesion, spreading, and proliferation. In this process, kindlin-2 knockdown impaired transient Rac1 activation, influencing Akt activation and AP-1 activity. In agreement with these data, pharmacological inhibition of Rac1 reduced MC3T3-E1 cell adhesion, spreading, and proliferation. Overall, these findings demonstrated that kindlin-2 governs Rac1 activation, which controls osteoblast function. Our findings provide the first insights concerning the function of kindlin-2 in osteoblast, and suggest that kindlin-2 is a critical mediator for osteoblast physiology.     

Possible involvement of a cyclic AMP-dependent mechanism in PACAP-induced proliferation and ERK activation in astrocytes

In cultured astrocytes, PACAP activates extracellular signal-regulated kinase (ERK) and induces cell proliferation at picomolar concentrations. Here, we examined the role of cyclic AMP signaling underlying the effects of PACAP. PACAP38 induced accumulation of cyclic AMP in astrocytes at concentrations as low as 10(-12)M. PACAP38 (10(-12)-10(-9)M)-stimulated cell proliferation was completely abolished by the cyclic AMP antagonist Rp-cAMP, whereas the protein kinase A (PKA) inhibitor H89 had no effect. This PACAP38-mediated effect was also abolished by the ERK kinase inhibitor PD98059, suggesting the involvement of ERK in PACAP-induced proliferation. PACAP38 (10(-12)M)-stimulated phosphorylation of ERK lasted for at least 60 min. This effect was completely abolished by Rp-cAMP but not by H89. Dibutyryl cyclic AMP maximally stimulated the incorporation of thymidine and activation of ERK at 10(-10)M. These results suggest that PACAP-mediated stimulation of ERK activity and proliferation of astrocytes may involve a cyclic AMP-dependent, but PKA-independent, pathway.     

Crystal structure of human mono-phosphorylated ERK1 at Tyr204

Extracellular signal-regulated kinase (ERK) is a member of the MAP kinase family, and can regulate several cellular responses. The isoforms ERK1 and ERK2 have markedly similar amino acid sequences, but exhibit distinctive physiological functions. As well as ERK2, ERK1 was auto- and mono-phosphorylated at Tyr204 in the activation loop during Escherichia coli production, resulting in basal level activity, approximately 500-fold less compared with fully-active ERK1 dual-phosphorylated at Thr202 and Tyr204. Crystal structure demonstrated that the mono-phosphorylated ERK1 kinase possessed a novel conformation distinguishable from the un-phosphorylated (inactive) and the dual-phosphorylated (full-active) forms. The characteristic structural features in both the C-helix and the activation loop likely contribute to the basal activity of the mono-phosphorylated ERK1. The structural dissection of ERK1 compared to ERK2 suggests that the structural differences in the D-motif binding site and in the backside binding site are putative targets for development of selective ERK1/ERK2 inhibitors.     

Regulation of adenylyl cyclase, ERK1/2, and CREB by Gz following acute and chronic activation of the delta-opioid receptor

Opioid tolerance and physical dependence in mammals can be rapidly induced by chronic exposure to opioid agonists. Recently, opioid receptors have been shown to interact with the pertussis toxin (PTX)-insensitive Gz (a member of the Gi subfamily), which inhibits adenylyl cyclase and stimulates mitogen-activated protein kinases (MAPKs). Here, we established stable human embryonic kidney 293 cell lines expressing delta-opioid receptors with or without Gz to examine the role of Gz in opioid receptor-regulated signaling systems. Each cell line was acutely or chronically treated with [D-Pen2,D-Pen5]enkephalin (DPDPE), a delta-selective agonist, in the absence or presence of PTX. Subsequently, the activities of adenylyl cyclase, cyclic AMP (cAMP)-dependent response element-binding proteins (CREBs), and MAPKs were measured by determining cAMP accumulation and phosphorylation of CREBs and the extracellular signal-regulated protein kinases (ERKs) 1 and 2. In cells coexpressing Gz, DPDPE inhibited forskolin-stimulated cAMP accumulation in a PTX-insensitive manner, but Gz could not replace Gi to mediate adenylyl cyclase supersensitization upon chronic opioid treatment. DPDPE-induced adenylyl cyclase supersensitization was not associated with an increase in the phosphorylation of CREBs. Both Gi and Gz mediated DPDPE-induced activation of ERK1/2, but these responses were abolished by chronic opioid treatment. Collectively, our results show that although Gz mediated opioid-induced inhibition of adenylyl cyclase and activation of ERK1/2, Gz alone was insufficient to mediate opioid-induced adenylyl cyclase supersensitization.     

Platelet ERK2 activation by thrombin is dependent on calcium and conventional protein kinases C but not Raf-1 or B-Raf

Extracellular signal-regulated kinase (ERK) activation pathways have been well characterized in a number of cell types but very few data are available for platelets. The thrombin-induced signaling pathway leading to ERK2 activation in platelets is largely uncharacterized. In this study, we investigated the kinases involved in thrombin-induced ERK2 activation in conditions of maximal ERK2 activation. We found that thrombin-induced mitogen-activated protein kinase/ERK kinase (MEK)1/2 activation was necessary for ERK2 phosphorylation. We obtained strong evidence that conventional protein kinase Cs (PKCs) and calcium are involved in thrombin-induced ERK2 activation. First, ERK2 and MEK1/2 phosphorylation was totally inhibited by low concentrations (1 microM) of RO318425, a specific inhibitor of conventional PKCs. Second, Ca(2+), from either intracellular pools or the extracellular medium, was necessary for ERK2 activation and conventional PKC activation, excluding the involvement of a new class of calcium-insensitive PKCs. Third, LY294002 and wortmannin had no significant effect on ERK2 activation, even at concentrations that inhibit phosphatidylinositol (PI)3-kinase (5 microM to 25 microM and 50 nM, respectively). This suggests that PI3-kinase was not necessary for ERK2 activation and therefore, that PI3-kinase-dependent atypical PKCs were not involved. Surprisingly, in contrast to proliferative cells, we found that the serine/threonine kinases Raf-1 and B-Raf were not an intermediate kinase between conventional PKCs and MEK1/2. After immunoprecipitation of Raf-1 and B-Raf, the basal glutathione S-transferase-MEK1 phosphorylation observed in resting platelets was not upregulated by thrombin and was still observed in the absence of anti-Raf-1 or anti-B-Raf antibodies. In these conditions, the in vitro cascade kinase assay did not detect any MEK activity. Thus in platelets, thrombin-induced ERK2 activation is activated by conventional PKCs independently of Raf-1 and B-Raf activation.     

Laminin alpha 5 mediates ectopic adhesion of hepatocellular carcinoma through integrins and/or Lutheran/basal cell adhesion molecule

Laminins are a diverse group of α/β/γ heterotrimers formed from five α, three β and three γ chains; they are major components of all basal laminae (BLs). One laminin chain that has garnered particular interest due to its widespread expression pattern and importance during development is laminin α5. Little is known, however, about the expression and function of laminins containing the α5 chain in human hepatocellular carcinoma (HCC). Here, using a specific antibody, we examined the expression of laminin α5 in normal liver and in HCCs. In normal liver, although laminin α5 was observed in hepatic BLs underlying blood vessels and bile ducts, it was absent from the parenchyma, which may be the origin of HCC. On the other hand, laminin α5 deposition was observed throughout all HCCs tested, regardless of tumor grade. In well-differentiated HCCs, it localized along the trabecules of the tumor. In poorly-differentiated HCCs, it was present in surrounding tumor nodules. In HCC cell lines, laminin α5 heterotrimerized with β and γ chains and was secreted into the culture media. To attempt to understand the function of laminins containing α5, the expression of its receptors in HCCs was also determined. In this regard, α3β1/α6β1 integrins and Lutheran/basal cell adhesion molecule (Lu/B-CAM) were expressed in HCC cells. In vitro studies showed that HCC cells readily attached to laminin containing the α5 chain, more so than did primary hepatocytes. In addition to α3β1/α6β1 integrins and Lu/B-CAM, laminin α5 was recognized by integrin α1β1, which also was expressed in HCC cells. These results suggest that laminins containing α5 serve as functional substrates regulating progression of HCC.     

Erythropoietin receptor Y479 couples to ERK1/2 activation via recruitment of phospholipase Cgamma

Red blood cell development is primarily controlled by erythropoietin (EPO). Several studies have revealed the importance of EPO-R Y343 and Y479 for erythroid cell growth, differentiation, and survival. In order to isolate critical signaling proteins that bind to EPO-R, we initiated a Cloning of Ligand Target (COLT) screen using a murine embryonic day 16 phage library and a biotinylated EPO-R Y343 phosphopeptide. One of the clones isolated encodes Phospholipase C (PLC)gamma1. PLCgamma1 is rapidly tyrosine phosphorylated upon EPO stimulation and associates with EPO-R in an SH2-domain-dependent manner. Although PLCgamma1 bound EPO-R Y343, Y401, Y429, Y431, and Y479 in the COLT screen, PLCgamma1 required Y479 for association with EPO-R in Ba/F3-EPO-R cells. Studies have identified EPO-R Y479 as important for ERK activation. Since PI3-kinase binds EPO-R Y479, one group has suggested that ERK activation downstream of PI3-kinase accounts for the importance of this residue in EPO signaling. However, we show that inhibition of PI3-kinase does not abolish ERK activation. Furthermore, we demonstrate interaction of PLCgamma1 with Grb2 and SOS2. Hence, we have identified a novel adapter function for PLCgamma1 in EPO signaling in which recruitment of PLCgamma1 to EPO-R may lead to activation of the ERK pathway.     

beta1 integrins modulate p66ShcA expression and EGF-induced MAP kinase activation in fetal lung cells

ShcA proteins mediate Erk1/Erk2 activation by integrins and epidermal growth factor (EGF), and are expressed as p46ShcA, p52ShcA, and p66ShcA. Although p52ShcA and p46ShcA mediate Erk1/Erk2 activation, p66ShcA antagonizes Erk activation. p66ShcA is spatially regulated during lung development, leading us to hypothesize that integrin signaling regulates p66ShcA expression and, consequently, EGF signaling. Fetal lung mesenchymal cells were isolated from E16 Swiss-Webster mice, stimulated with oligopeptide extracellular matrix analogs or anti-integrin antibodies, and subjected to ShcA Western analyses and EGF-stimulated Erk1/Erk2 kinase assays. p66ShcA expression was decreased by anti-alpha1 integrin antibody and DGEA collagen analog, and increased by anti-beta1, anti-alpha4, and anti-alpha5 integrin antibodies and RGDS fibronectin analog. Paradoxically, beta1 integrin stimulation increased EGF-induced Erk activation while increasing expression of the inhibitory p66ShcA isoform. This paradox was resolved by demonstrating that Erk inhibition attenuates integrin-mediated p66ShcA induction. These results suggest that p66ShcA is up-regulated as inhibitory feedback on integrin-mediated Erk activation.     

Gadolinium-promoted cell cycle progression with enhanced S-phase entry via activation of both ERK and PI3K signaling pathways in NIH 3T3 cells

The aim of this study was to investigate whether Gd is able to exert the proliferation-promoting effect and to explore its possible underlying mechanism. We showed that Gd promoted cell cycle progression with increased S-phase entry in a concentration- and time-dependent manner in NIH 3T3 cells. The effect was further evidenced by the expressions of key proteins in driving cells through the G₁/S transition point of the cell cycle. In the presence of Gd, the protein levels of cyclins D, E, and A were dramatically increased and demonstrated a characteristically temporal pattern of sequential mitotic events. Additionally, the levels of phosphorylated retinoblastoma protein were also significantly increased at certain time periods. To further elucidate the underlying mechanism, extracellular signal-regulated kinase and phosphatidylinositol 3-kinase signaling pathways were assessed. Both pathways were activated by Gd. Moreover, the levels of cyclin D and cyclin A were evaluated after the addition of the pharmacological inhibitors at early and late G₁ phases, correspondingly, to reveal the contribution of the two pathways in the Gd-promoted G₁/S transition. It showed that both pathways were needed for Gd-promoted cell cycle progression. The results presented here provide novel evidence to advance knowledge leading to further understanding of the mechanisms of both cell growth and death caused by Gd and may be helpful for more rational application of Gd-based compounds in the future.     

脊髓细胞外调节激酶1/2在大鼠后足切割痛中的表达和作用

目的：探讨大鼠后足切割后脊髓ERK的表达情况。方法：以大鼠右后足切割作为急性疼痛模型;用免疫组织化学法测试脊髓磷酸化ERK（pERK）表达情况。ERK抑制剂U0126（1μg）在切割前20min或切割后20min鞘内注射。用von Frey纤维测试大鼠机械性痛敏。结果：大鼠后足切割后1min,在切割侧L4-L5脊髓浅层背侧角（板层Ⅰ和板层Ⅱ）ERK被迅速地激活,并在5min达到峰值,随后恢复到基础值。切割前鞘内给予U0126能显著减轻机械性痛敏,然而,切割后鞘内给予U0126对机械性痛敏的作用并不明显。结论：脊髓ERK在大鼠后足切割痛中产生机械性痛敏发挥了重要的作用。     

Dextran sulfate sodium enhances interleukin-1 beta release via activation of p38 MAPK and ERK1/2 pathways in murine peritoneal macrophages

Interleukin (IL)-1 beta is a pro-inflammatory cytokine that has been shown to play a pivotal role in the onset of inflammatory bowel disease (IBD), however, the molecular mechanisms underlying the production of IL-1 beta in IBD are not fully understood. We investigated dextran sulfate sodium (DSS)-induced IL-1 beta production and caspase-1 activities in murine peritoneal macrophages (pM phi). Further, the activation status of p38 mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase 1/2 (ERK1/2), and c-Jun NH(2)-terminal kinase (JNK1/2), as well as their upstream target kinases, were examined by Western blotting. In addition, mRNA expression was assessed by RT-PCR and CXC chemokine ligand 16 (CXCL16) protein was detected by immunocytochemistry. DSS-treated pM phi released IL-1 beta protein in a time-dependent manner without affecting mRNA levels during 3-24 h, and caspase-1 activity peaked at 5 min (29-fold). IL-1 beta release and caspase-1 activity induced by DSS were significantly inhibited by a MAPK kinase 1/2 inhibitor, a p38 MAPK inhibitor, and NAC, however, not by JNK1/2 or a protein kinase C inhibitor. In addition, DSS strikingly induced the phosphorylation of p38 MAPK and ERK1/2 within 2 and 10 min, respectively. DSS also induced intracellular generation of reactive oxygen species (ROS). Pre-treatment with anti-CXCL16 for 24 h, but not anti-scavenger receptor-A, anti-CD36, or anti-CD68 antibodies, significantly suppressed DSS-induced IL-1 beta production. Our results suggest that DSS triggers the release of IL-1 beta protein from murine pM phi at a post-translational level through binding with CXCL16, ROS generation, and resultant activation of both p38 MAPK and ERK1/2 pathways, and finally caspase-1 activation.     

Syndecan- and integrin-binding peptides synergistically accelerate cell adhesion

Integrins and syndecans mediate cell adhesion to extracellular matrix and their synergistic cooperation is implicated in cell adhesion processes. We previously identified two active peptides, AG73 and EF1, from the laminin α1 chain LG4 module, that promote cell attachment through syndecan- and α2β1 integrin-binding, respectively. Here, we examined time-dependent cell attachment on the mixed peptides AG73/EF1. The AG73/EF1 promoted stronger and more rapid cell attachment, spreading, FAK phosphorylation that reached a maximum at 20 min than that on AG73 (40 min) or EF1 (90 min) supplied singly. Thus, the syndecan- and α2β1 integrin-binding peptides synergistically affect cells and accelerate cell adhesion.