Actin Filament Remodeling Research Articles

Rab7b at the intersection of intracellular trafficking and cell migration

Rab proteins are small GTPases essential for controlling and coordinating intracellular traffic. The small GTPase Rab7b regulates the retrograde transport from late endosomes toward the Trans-Golgi Network (TGN), and is important for the proper trafficking of several receptors such as Toll-like receptors (TLRs) and sorting receptors. We recently identified the actin motor protein myosin II as a new interaction partner for Rab7b, and found that Rab7b transport is dependent on myosin II. Interestingly, we also discovered that Rab7b influences the phosphorylation state of myosin II by controlling the activation status of the small GTPase RhoA. Consequently, Rab7b is important for the remodeling of actin filaments in processes such as stress fiber formation, cell adhesion, polarization and cell migration. Our finding that Rab7b can control actomyosin reorganization reveals yet another important role for Rab proteins, in addition to their already established role as master regulators of intracellular transport. Here we discuss our findings and speculate how they can explain the importance of Rab7b in dendritic cells (DCs).

SMIFH2 has effects on Formins and p53 that perturb the cell cytoskeleton.

Formin proteins are key regulators of the cytoskeleton involved in developmental and homeostatic programs, and human disease. For these reasons, small molecules interfering with Formins’ activity have gained increasing attention. Among them, small molecule inhibitor of Formin Homology 2 domains (SMIFH2) is often used as a pharmacological Formin blocker. Although SMIFH2 inhibits actin polymerization by Formins and affects the actin cytoskeleton, its cellular mechanism of action and target specificity remain unclear.Here we show that SMIFH2 induces remodelling of actin filaments, microtubules and the Golgi complex as a result of its effects on Formins and p53.We found that SMIFH2 triggers alternated depolymerization-repolymerization cycles of actin and tubulin, increases cell migration, causes scattering of the Golgi complex, and also cytotoxicity at high dose. Moreover, SMIFH2 reduces expression and activity of p53 through a post-transcriptional, proteasome-independent mechanism that influences remodelling of the cytoskeleton.As the action of SMIFH2 may go beyond Formin inhibition, only short-term and low-dose SMIFH2 treatments minimize confounding effects induced by loss of p53 and cytotoxicity.

A Novel Approach against Vascular Intimal Hyperplasia Through the Suppression of Girdin.

Intimal hyperplasia is an impediment to patency in both arteries after percutaneous angioplasty (PTA) and veingraft. It is well known that migration and proliferation of vascular smooth muscle cells (SMCs) influence the vascular remodeling process, there are no therapies to prevent intimal hyperplasia of post-PTA arteries and vein grafts. Girdin (girders of actin filaments), also known as Gα-interacting vesicle associated protein (GIV) is a novel actin-binding Akt substrate.Girdin is highly expressed in limited types of cells such as smooth muscle cells, neuroblasts, and cancer cells. Girdin is involved in the cell migration, proliferation and remodeling of actin filaments. This study revealed that Girdin is involved with intimal hyperplasia in carotid arteries after balloon injury and vein grafts and vascular SMCs migration and proliferation. There are suggestions that Girdin has pivotal roles in migration and proliferation of vascular SMCs and that gene therapy targeting Girdin could be a novel therapeutic strategy for restenosis after PTA and vein graft failure.

Thrombospondin-1 Modulates Actin Filament Remodeling and Cell Motility in Mouse Mammary Tumor cells in Vitro.

It is well established that the secretion of thrombospondin-1 (TSP-1) by activated stromal cells and its accumulation in the tumor microenvironment during dysplasia inhibits primary tumor growth through inhibition of angiogenesis. This inhibitory function of TSP-1 is actuated either by inhibiting MMP9 activation and the release of VEGF from extracellular matrix or by an interaction with CD36 on the surface of endothelial cells resulting in an increase in apoptosis. In contrast, several published articles have also shown that as tumor cells become more invasive and enter the early stage of carcinoma, they up-regulate TSP-1 expression, which may promote invasion and migration. In our in vivo studies using the polyoma middle T antigen (PyT) transgenic mouse model of breast cancer, we observed that the absence of TSP-1 significantly increased the growth of primary tumors, but delayed metastasis to the lungs. In this study, we propose a mechanism for the promigratory function of TSP-1 in mouse mammary tumor cells in vitro. We demonstrate the correlations between expression of TSP-1 and its receptor integrin α3β1, which is considered a promigratory protein in cancer cells. In addition we propose that binding of TSP-1 to integrin α3β1 is important for mediating actin filament polymerization and therefore, cell motility. These findings can help explain the dual functionality of TSP-1 in cancer progression.

LY2157299-loaded carriers inhibiting wound healing in hepatocellular carcinoma

post-translational modifications, of many proteins involved in the cytoskeleton organization with respect to controls. In particular, higher levels of phosphorylated cofilin (p-COF)weredetected in the patient. p-COF was reported to be essential for the remodelling of cellular actin filaments. Here we show that higher levels of pCOF in PDfibroblasts coincidewithanhigher amountof stressfibreswhich appeared randomly oriented with consequent dramatic effects on both the cell morphology and the cell elasticity, as revealed by confocal laser scanning microscopy and atomic force microscopy measurements. Taken together, our results point out an important role of the cofilin pathway in the cellular homeostasis impairment in parkin-mutant human primary fibroblasts.

Ezrin is required for epithelial-mesenchymal transition induced by TGF-β1 in A549 cells

Epithelial mesenchymal transition (EMT) has been shown to play a role in cellular differentiation during deve-lopment and tumor invasion. However, the precise molecular mechanisms of EMT are not fully elucidated. Previous studies suggested that the mechanism underlying the possible involvement of ezrin in EMT process might be different from that of moesin, another ERM protein. In our study, we examined the role of ezrin in actin filament reorganization and cell meta-stasis during TGF-β1-induced alveolar EMT. Suppressing ezrin expression limited morphological changes and actin filament remodeling, decreased cell migration and invasion during EMT. Immunofluorescence experiments indicated that EMT characteristics in lung cancer cells are associated to differential ezrin subcellular localization. We also found that podocalyxin interacted with ezrin after TGF-β1 induction. Therefore, ezrin is an important regulator of the EMT process, and its function might possibly be mediated by the ezrin-podocalyxin interaction during TGF-β1-induced alveolar EMT. Our finding provides important new insights into the mechanisms of action of the ERM proteins in the TGF-β1-induced alveolar EMT.

Tropomodulin3 as the link between insulin-activated AKT2 and cortical actin remodeling in preparation of GLUT4 exocytosis.

It is well established that insulin-induced remodeling of actin filaments into a cortical mesh is required for insulin-stimulated GLUT4 exocytosis. Akt2 and its downstream effectors play a pivotal role in mediating the translocation and membrane fusion of GLUT4-storage vesicle (GSV). However, the direct downstream effector underlying the event of cortical actin reorganization has not been elucidated. In a recent study in Nature Communications, (1) Lim etal identify Tropomodulin3 (Tmod3) as a downstream target of the Akt2 kinase and describe the role of this pointed-end actin-capping protein in regulating insulin-dependent exocytosis of GSVs in adipocytes through the remodeling of the cortical actin network. Phosphorylation of Tmod3 by Akt2 on Ser71 modulates insulin-induced actin remodeling, a key step for GSV fusion with the plasma membrane (PM). Furthermore, the authors establish Tm5NM1 (Tpm3.1 in new nomenclature) (2) as the cognate tropomyosin partner of Tmod3, and an essential role of Tmod3-Tm5NM1 interaction for GSV exocytosis and glucose uptake. This study elucidates a novel effector of Akt2 that provides a direct mechanistic link between Akt2 signaling and actin reorganization essential for vesicle fusion, and suggests that a subset of actin filaments with specific molecular compositions may be dedicated for the process of vesicle fusion.

Dynamin2 organizes lamellipodial actin networks to orchestrate lamellar actomyosin.

Actin networks in migrating cells exist as several interdependent structures: sheet-like networks of branched actin filaments in lamellipodia; arrays of bundled actin filaments co-assembled with myosin II in lamellae; and actin filaments that engage focal adhesions. How these dynamic networks are integrated and coordinated to maintain a coherent actin cytoskeleton in migrating cells is not known. We show that the large GTPase dynamin2 is enriched in the distal lamellipod where it regulates lamellipodial actin networks as they form and flow in U2-OS cells. Within lamellipodia, dynamin2 regulated the spatiotemporal distributions of α-actinin and cortactin, two actin-binding proteins that specify actin network architecture. Dynamin2's action on lamellipodial F-actin influenced the formation and retrograde flow of lamellar actomyosin via direct and indirect interactions with actin filaments and a finely tuned GTP hydrolysis activity. Expression in dynamin2-depleted cells of a mutant dynamin2 protein that restores endocytic activity, but not activities that remodel actin filaments, demonstrated that actin filament remodeling by dynamin2 did not depend of its functions in endocytosis. Thus, dynamin2 acts within lamellipodia to organize actin filaments and regulate assembly and flow of lamellar actomyosin. We hypothesize that through its actions on lamellipodial F-actin, dynamin2 generates F-actin structures that give rise to lamellar actomyosin and for efficient coupling of F-actin at focal adhesions. In this way, dynamin2 orchestrates the global actin cytoskeleton.

Tracking and quantifying focal adhesion kinase and paxillin at lamellipodial protrusion in migrating endothelial cells (696.5)

Focal adhesion kinase (FAK) and paxillin are involved in focal adhesion (FA) disassembly and formation, which can regulate cell migration, intracellular signaling, and remodeling of actin filaments. We used time‐lapse double‐color imaging to monitor concurrently the spatial‐temporal dynamics of FAK and paxillin in live endothelial cells (ECs) co‐transfected with GFP‐FAK and DsRed‐paxillin, and the fluorescence intensities (FI) of paxillin and FAK at FAs were determined in cell front, center and rear. The mean FAK/Paxillin FI ratio is highest at cell front (mean±SEM: 4.73±0.48), near 1 at cell center (0.95±0.11), and lowest at cell rear (0.64±0.05) (P<0.01). Determination of the time difference between the assemblies of FAK and paxillin at FAs in lamellipodial protrusion (LP) showed that FAK assembly occurs ahead of that of paxillin at individual FAs. Computational analysis indicates that FAK reaches its maximum intensity earlier than paxillin by about 4 min. The assembly of FAK is at LP ahead of paxillin Indicates that, while both molecules play important roles in modulating FA dynamics during cell migration, FAK promotes FA formation ahead of paxillin at the cell leading edge. This work was supported by NHLBI Research Grants HL‐104402 and HL‐106579 (S.C.).

The β-actin mRNA zipcode regulates epithelial adherens junction assembly but not maintenance

Epithelial cell-cell contact stimulates actin cytoskeleton remodeling to down-regulate branched filament polymerization-driven lamellar protrusion and subsequently to assemble linear actin filaments required for E-cadherin anchoring during adherens junction complex assembly. In this manuscript, we demonstrate that de novo protein synthesis, the β-actin 3' UTR, and the β-actin mRNA zipcode are required for epithelial adherens junction complex assembly but not maintenance. Specifically, we demonstrate that perturbing cell-cell contact-localized β-actin monomer synthesis causes epithelial adherens junction assembly defects. Consequently, inhibiting β-actin mRNA zipcode/ZBP1 interactions with β-actin mRNA zipcode antisense oligonucleotides, to intentionally delocalize β-actin monomer synthesis, is sufficient to perturb adherens junction assembly following epithelial cell-cell contact. Additionally, we demonstrate active RhoA, the signal required to drive zipcode-mediated β-actin mRNA targeting, is localized at epithelial cell-cell contact sites in a β-actin mRNA zipcode-dependent manner. Moreover, chemically inhibiting Src kinase activity prevents the local stimulation of β-actin monomer synthesis at cell-cell contact sites while inhibiting epithelial adherens junction assembly. Together, these data demonstrate that epithelial cell-cell contact stimulates β-actin mRNA zipcode-mediated monomer synthesis to spatially regulate actin filament remodeling, thereby controlling adherens junction assembly to modulate cell and tissue adhesion.

Abstract B3: HSP27 is required for invasion and metastasis triggered by hepatocyte growth factor

Abstract The Hepatocyte Growth Factor (HGF) also known as Scatter Factor, activates cancer cell invasion and metastasis. We show that in ovarian cancer cells HGF induced the phosphorylation of the small heat shock protein of 27KDa (HSP27) by activating the p38MAPK. HSP27 is increased in many cancers at advanced stage including ovarian cancer and associated with cancer resistance to therapy and poor patients' survival. The phosphorylation of HSP27 regulates both its chaperone activity and its control of cytoskeletal stability. We show that HSP27 was necessary for the motility in vitro and the remodeling of actin filaments induced by HGF. In vivo, HSP27 silencing impaired the ability of the highly metastatic, HGF-secreting ovarian cancer cells to give rise to spontaneous metastases. This was due to defective motility across the vessel wall and reduced growth. Indeed, HSP27 silencing impaired both the ability of ovarian cancer cells to form experimental haematogenous metastases and to grow as subcutaneous xenografts. Moreover, HSP27 suppression resulted in the sensitization of xenografts to low doses of the chemotherapeutic Paclitaxel, likely because HSP27 protected microtubules from bundling caused by the drug. Altogether, these data show that the HSP27 is required for the pro-invasive and pro-metastatic activity of HGF and suggest that HSP27 might be not only a marker of progression of ovarian cancer, but also a suitable target for therapy. Grant sponsors: This work has been supported by grants to M.F.D.: 2012 IG grant and 2010 Special Program Molecular Clinical Oncology 5xMille of the Italian Association of Cancer Research (AIRC), Project n° 9970, and Grant of the CARIPLO Foundation. Citation Format: Simona Pavan, Daniele Musiani, Erica Torchiaro, Giorgia Migliardi, Jessica Erriquez, Martina Olivero, Maria Flavia Di Renzo. HSP27 is required for invasion and metastasis triggered by hepatocyte growth factor. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: From Concept to Clinic; Sep 18-21, 2013; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2013;19(19 Suppl):Abstract nr B3.

HSP27 is required for invasion and metastasis triggered by hepatocyte growth factor

The hepatocyte growth factor (HGF) also known as scatter factor activates cancer cell invasion and metastasis. We show that in ovarian cancer cells HGF induced the phosphorylation of the small heat shock protein of 27 kDa (HSP27) by activating the p38MAPK. HSP27 is increased in many cancers at advanced stage including ovarian cancer and associated with cancer resistance to therapy and poor patients' survival. The phosphorylation of HSP27 regulates both its chaperone activity and its control of cytoskeletal stability. We show that HSP27 was necessary for the remodeling of actin filaments induced by HGF and that motility in vitro depended on the p38MAPK-MK2 axis. In vivo, HSP27 silencing impaired the ability of the highly metastatic, HGF-secreting ovarian cancer cells to give rise to spontaneous metastases. This was due to defective motility across the vessel wall and reduced growth. Indeed, HSP27 silencing impaired the ability of circulating ovarian cancer cells to home to the lungs and to form experimental hematogenous metastases and the capability of cancer cells to grow as subcutaneous xenografts. Moreover, HSP27 suppression resulted in the sensitization of xenografts to low doses of the chemotherapeutic paclitaxel, likely because HSP27 protected microtubules from bundling caused by the drug. Altogether, these data show that the HSP27 is required for the proinvasive and prometastatic activity of HGF and suggest that HSP27 might be not only a marker of progression of ovarian cancer, but also a suitable target for therapy.

Putting Rac1 on the Path to Glucose Uptake

In spite of numerous and key advances in our understanding of insulin signaling, the molecular basis for impaired insulin-stimulated glucose uptake underlying insulin resistance remains unclear. Because skeletal muscle accounts for the majority of glucose utilization in the postprandial insulin-regulated state, defects in insulin action in muscle can determine whole-body glucose utilization. In muscle and fat cells, overall similarities exist in the signals emanating from the insulin receptor that mobilize glucose transporter GLUT4 to the membrane. Importantly, defects in the signaling network connecting the activated insulin receptor to GLUT4 vesicles are of particular consequence to insulin resistance in muscle, where, unlike the case of fat cells, GLUT4 expression is not significantly reduced. The complex structural organization of muscle tissue and its associated cells have limited the molecular scrutiny of glucose uptake regulation. Instead, cell culture systems have been instrumental in revealing intricacies in the signals and traffic machinery mobilizing GLUT4 to the membrane. This signaling relay is initiated by insulin receptor substrate (IRS)-1 (and not IRS-2)–associated activation of class I phosphatidylinositol-3-kinase (PI3K). At this point, a signal bifurcation takes place, one arm leading to Akt2 activation, inhibition of its substrate AS160 (a GTPase-activating protein for Rabs) and consequent activation of its target Rab GTPases, which in skeletal muscle cells are Rab8A and Rab13 (1). The other arm leads to Rac1, a Rho-family GTPase (2,3) that enacts a dynamic cycle of cortical actin filament remodeling through the Arp2/3 complex and cofilin (4). Joint activation of these distinct signaling arms is required …

The Effect of Mild Hyperthermia on Morphology, Ultrastructure and F-Actin Organization in HL-60 Cell Line

Introduction. Hyperthermia is a well-established physical stimulus, which is applied as an adjunctive therapy with various cancer treatments, such as radiotherapy and chemotherapy. However, the precise mechanism of heat action at the cellular level remains to be elucidated, and appears to be multi-dimensional. The purpose of the current study was to determine the effect of mild hyperthermia on the actin cytoskeleton in the HL-60 cell line. In addition, the morphological and ultrastructural approaches were used to determine the type of hyperthermia-induced cell death. Material and methods. All studies were performed using human promyelocytic leukemia cell line (HL-60). Actin filaments were visualized with phalloidin conjugated to Alexa Fluor® 488 using fluorescence microscopy. Morphological and ultrastructural changes in the HL-60 cells were analysed by light and electron microscopy, respectively. Results. Exposure of HL-60 cells to mild hyperthermia resulted in the reorganization of the actin cytoskeleton and the appearance of characteristic apoptotic features, including cell shrinkage, chromatin condensation and margination. In addition, swollen mitochondria were observed. The morphological and ultrastructural changes increased in severity with an increase in recovery time. Similarly, actin filament remodeling was observed immediately after the heat shock and was more evident 3 and 6 hrs after the treatment. These effects were mainly reflected by a higher definition of the dense cortical F-actin ring as well as the appearance of brightly fluorescent F-actin dots and networks scattered throughout the cytoplasm. Conclusions. Presented data suggest that actin filament reorganization is involved in the process of apoptosis initiated by mild hyperthermia. Furthermore, the results of our studies showed that the severity of hyperthermia-induced morphological and ultrastructural changes as well as alterations in actin organization depend not only on the temperature treatment but also on the duration of post heat shock recovery

1P206 引っ張り刺激による細胞シート中のアクチンフィラメント再編成(12.細胞生物的課題,ポスター,日本生物物理学会年会第51回(2013年度))

1P206 引っ張り刺激による細胞シート中のアクチンフィラメント再編成(12.細胞生物的課題,ポスター,日本生物物理学会年会第51回(2013年度))

Elevated tropomyosin expression is associated with epithelial–mesenchymal transition of lens epithelial cells

Injury to lens epithelial cells (LECs) leads to epithelial–mesenchymal transition (EMT) with resultant fibrosis. The tropomyosin (Tpm) family of cytoskeleton proteins is involved in regulating and stabilizing actin microfilaments. Aberrant expression of Tpms leads to abnormal morphological changes with disintegration of epithelial integrity. The EMT of LECs has been proposed as a major cause of posterior capsule opacification (PCO) after cataract surgery. Using in vivo rodent PCO and human cataractous LECs, we demonstrated that the aberrant expression of rat Tpm and human Tpm1α/2β suggested their association in remodelling of the actin cytoskeleton during EMT of LECs. Expression analysis from abnormally growing LECs after lens extraction revealed elevated expression of α-smooth muscle actin (α-SMA), a marker for EMT. Importantly, these cells displayed increased expression of Tpm1α/2β following EMT/PCO formation. Expression of Tpm1α/2β was up-regulated in LECs isolated from cataractous lenses of Shumiya Cataract Rats (SCRs), compared with non-cataractous lenses. Also, LECs from human patients with nuclear cataract and anterior subcapsular fibrosis (ASF) displayed significantly increased expression of Tpm2β mRNA, suggesting that similar signalling invokes the expression of these molecules in LECs of cataractous SCR and human lenses. EMT was observed in LECs overexpressed with Tpm1α/2β, as evidenced by increased expression of α-SMA. These conditions were correlated with remodelling of actin filaments, possibly leading to EMT/PCO and ASF. The present findings may help clarify the condition of the actin cytoskeleton during morphogenetic EMT, and may contribute to development of Tpm-based inhibitors for postponing PCO and cataractogenesis.

Myo1c binding to submembrane actin mediates insulin-induced tethering of GLUT4 vesicles

GLUT4-containing vesicles cycle between the plasma membrane and intracellular compartments. Insulin promotes GLUT4 exocytosis by regulating GLUT4 vesicle arrival at the cell periphery and its subsequent tethering, docking, and fusion with the plasma membrane. The molecular machinery involved in GLUT4 vesicle tethering is unknown. We show here that Myo1c, an actin-based motor protein that associates with membranes and actin filaments, is required for insulin-induced vesicle tethering in muscle cells. Myo1c was found to associate with both mobile and tethered GLUT4 vesicles and to be required for vesicle capture in the total internal reflection fluorescence (TIRF) zone beneath the plasma membrane. Myo1c knockdown or overexpression of an actin binding-deficient Myo1c mutant abolished insulin-induced vesicle immobilization, increased GLUT4 vesicle velocity in the TIRF zone, and prevented their externalization. Conversely, Myo1c overexpression immobilized GLUT4 vesicles in the TIRF zone and promoted insulin-induced GLUT4 exposure to the extracellular milieu. Myo1c also contributed to insulin-dependent actin filament remodeling. Thus we propose that interaction of vesicular Myo1c with cortical actin filaments is required for insulin-mediated tethering of GLUT4 vesicles and for efficient GLUT4 surface delivery in muscle cells.

Molecular Cooperativity of Drebrin1-300 Binding and Structural Remodeling of F-Actin

Drebrin A, an actin-binding protein, is a key regulatory element in synaptic plasticity of neuronal dendrites. Understanding how drebrin binds and remodels F-actin is important for a functional analysis of their interactions. Conventionally, molecular models for protein-protein interactions use binding parameters derived from bulk solution measurements with limited spatial resolution, and the inherent assumption of homogeneous binding sites. In the case of actin filaments, their structural and dynamic states—as well as local changes in those states—may influence their binding parameters and interaction cooperativity. Here, we probed the structural remodeling of single actin filaments and the binding cooperativity of DrebrinA1-300 –F–actin using AFM imaging. We show direct evidence of DrebrinA1-300-induced cooperative changes in the helical structure of F-actin and observe the binding cooperativity of drebrin to F-actin with nanometer resolution. The data confirm at the in vitro molecular level that variations in the F-actin helical structure can be modulated by cooperative binding of actin-binding proteins.

Insulin-Induced Endothelial Cell Cortical Actin Filament Remodeling: A Requirement for Trans-Endothelial Insulin Transport

Insulin's trans-endothelial transport (TET) is critical for its metabolic action on muscle and involves trafficking of insulin bound to its receptor (or at high insulin concentrations, the IGF-I receptor) via caveolae. However, whether caveolae-mediated insulin TET involves actin cytoskeleton organization is unknown. Here we address whether insulin regulates actin filament organization in bovine aortic endothelial cells (bAEC) and whether this affects insulin uptake and TET. We found that insulin induced extensive cortical actin filament remodeling within 5 min. This remodeling was inhibited not only by disruption of actin microfilament organization but also by inhibition of phosphatidylinositol 3-kinase (PI3K) or by disruption of lipid rafts using respective specific inhibitors. Knockdown of either caveolin-1 or Akt using specific small interfering RNA also eliminated the insulin-induced cortical actin filament remodeling. Blocking either actin microfilament organization or PI3K pathway signaling inhibited both insulin uptake and TET. Disruption of actin microfilament organization also reduced the caveolin-1, insulin receptor, and IGF-I receptor located at the plasma membrane. Exposing bAEC for 6 h to either TNFα or IL-6 blocked insulin-induced cortical actin remodeling. Extended exposure (24 h) also inhibited actin expression at both mRNA and protein levels. We conclude that insulin-induced cortical actin filament remodeling in bAEC is required for insulin's TET in a PI3K/Akt and plasma membrane lipid rafts/caveolae-dependent fashion, and proinflammatory cytokines TNFα and IL-6 block this process.

The influence of surfactants and hydrolyzed proteins on keratinocytes viability and elasticity

The knowledge how surfactants and hydrolyzed proteins influence the elastic properties of living epidermal keratinocytes is sparse. We demonstrate that the stiffness of cells measured by atomic force microscope (AFM) can be correlated with viability test. The effects of sodium lauryl sulphate (SLS) and hydrolyzed collagen (HK) of molecular weight 9 kDa were examined with respect to human keratinocytes viability and elasticity. MTT assay was applied to determine the survival fraction of keratinocytes treated with SLS and HK solutions of various molar ratios. The AFM measurements of the keratinocytes stiffness were carried out immediately after the exposure of cells to the SLS and HK, respectively. The increase of the SLS concentration resulted in the decrease of cells proliferation and this effect was inhibited by addition of HK. The strongest inhibition was observed for the SLS:HK molar ratio equals to 2:1. AFM study shows decrease in the cell stiffness for cells treated with SLS. Fluorescence microscopy reveals remodeling of actin filaments of SLS-treated cells. SLS:HK mixture treatment results in mechanical stiffness close to untreated cells. These results provide possible correlations between mechanical properties and viability of keratinocytes when the chemical stress occurs.