Breeding of a Near-Isogenic Wheat Line Resistant to Wheat Blast at Both Seedling and Heading Stages Through Incorporation of Rmg8.

Wheat blast caused by Pyricularia oryzae pathotype Triticum (MoT) has been transmitted from South America to Bangladesh and Zambia and is now spreading in these countries. To prepare against its further spread to Asian countries, we introduced Rmg8, a gene for resistance to wheat blast, into a Japanese elite cultivar, Chikugoizumi (ChI), through recurrent backcrosses and established ChI near-isogenic lines, #2-1-10 with the Rmg8/Rmg8 genotype and #4-2-10 with the rmg8/rmg8 genotype. A molecular analysis suggested that at least 96.6% of the #2-1-10 genome was derived from the recurrent parent ChI. The #2-1-10 line was resistant to MoT not only in primary leaves at the seedling stage but also in spikes and flag leaves at the heading stage. The strength of the resistance in spikes of this Rmg8 carrier was comparable to that of a carrier of the 2NS segment, which has been the only genetic resource released to farmers' fields for wheat blast resistance. On the other hand, the 2NS resistance was not expressed on leaves at the seedling stage nor flag leaves at the heading stage. Considering that leaf blast has been increasingly reported and regarded as an important inoculum source for spike blast, Rmg8 expressed at both the seedling and heading stages, or more strictly in both leaves and spikes, is suggested to be useful to prevent the spread of MoT in Asia and Africa.

Population pharmacokinetic analysis of peficitinib in patients with rheumatoid arthritis.

AIMS: To analyse the population pharmacokinetics (PK) of peficitinib in patients with rheumatoid arthritis (RA) and assess the potential PK covariates to identify the requirement for dose adjustment in RA patients. METHODS: The analysis incorporated 2464 observations from 98 healthy volunteers and 4919 observations from 989 RA patients. A population PK model for peficitinib in RA patients was constructed by a nonlinear mixed effect model using NONMEM with prior information from a healthy volunteer model. RESULTS: A 2-compartment model with sequential zero- and first-order absorption and lag time was constructed for RA patients. Covariate exploration in the RA patient model revealed that estimated glomerular filtration rate (eGFR) and lymphocyte count had a significant effect on apparent total systemic clearance (CL), which was 91.7 L/h (2.3% relative standard error). Compared with the mean population CL, the model predicted mean changes in CL of 12.3 and -10.7% in patients with observed minimum and maximum lymphocyte count of 500 and 4600 106 /L, respectively, and mean changes in CL of -17.8 and 16.7% in patients with minimum and maximum eGFR of 36.4 and 188 mL/min/1.73m2 , respectively. The simulated population mean area under plasma concentration-time curve for 24 hours after dosing showed a 1.35-fold increase in patients with severe renal impairment (eGFR 22.5 mL/min/1.73m2 ) compared with patients with reference eGFR (91.5 mL/min/1.73m2 ). CONCLUSION: The population PK model identified eGFR and lymphocyte count as covariates for CL. The magnitude of changes was not considered clinically relevant, indicating no requirement for dose adjustment.

Brief Exposure of Skin to Near-Infrared Laser Modulates Mast Cell Function and Augments the Immune Response.

The treatment of skin with a low-power continuous-wave (CW) near-infrared (NIR) laser prior to vaccination is an emerging strategy to augment the immune response to intradermal vaccine, potentially substituting for chemical adjuvant, which has been linked to adverse effects of vaccines. This approach proved to be low cost, simple, small, and readily translatable compared with the previously explored pulsed-wave medical lasers. However, little is known on the mode of laser-tissue interaction eliciting the adjuvant effect. In this study, we sought to identify the pathways leading to the immunological events by examining the alteration of responses resulting from genetic ablation of innate subsets including mast cells and specific dendritic cell populations in an established model of intradermal vaccination and analyzing functional changes of skin microcirculation upon the CW NIR laser treatment in mice. We found that a CW NIR laser transiently stimulates mast cells via generation of reactive oxygen species, establishes an immunostimulatory milieu in the exposed tissue, and provides migration cues for dermal CD103+ dendritic cells without inducing prolonged inflammation, ultimately augmenting the adaptive immune response. These results indicate that use of an NIR laser with distinct wavelength and power is a safe and effective tool to reproducibly modulate innate programs in skin. These mechanistic findings would accelerate the clinical translation of this technology and warrant further explorations into the broader application of NIR lasers to the treatment of immune-related skin diseases.

A drug-drug interaction study to evaluate the impact of peficitinib on OCT1- and MATE1-mediated transport of metformin in healthy volunteers.

PURPOSE: Peficitinib is an oral pan-Janus kinase inhibitor for the treatment of rheumatoid arthritis. Co-administration of peficitinib with metformin, a type 2 diabetes therapy, can occur in clinical practice. Hepatic and renal uptake of metformin is mediated by organic cation transporter 1 (OCT1) and OCT2, respectively, and its renal excretion by multidrug and toxin extrusion 1 (MATE1) and MATE2-K. This study investigated the effect of peficitinib on metformin pharmacokinetics in vitro and in healthy volunteers. METHODS: Inhibitory effects of peficitinib and its metabolite H2 on metformin uptake into human OCT1/2- and MATE1/2-K-expressing cells were assessed in vitro. In an open-label, drug-drug interaction study, 24 healthy volunteers received a single dose of metformin 750 mg on Days 1 and 10, and a single dose of peficitinib 150 mg on Days 3 and 5-11. Blood and urine samples were collected pre-dose on Days 1 and 10, and at intervals ≤ 48 h post-dose. Metformin concentration was determined by liquid chromatography-tandem mass spectrometry and its pharmacokinetic parameters calculated. RESULTS: Peficitinib, but not H2, inhibited metformin uptake into OCT1- and MATE1/2-K-expressing cells. Repeated-dose administration of peficitinib reduced metformin area under the concentration-time curve from 0 h extrapolated to infinity (AUCinf) by 17.4%, maximum plasma concentration (Cmax) by 17.0%, and renal clearance (CLR) by 12.9%. Co-administration of peficitinib with metformin was generally well tolerated. CONCLUSION: Slight changes in AUCinf, Cmax and CLR of metformin were observed when co-administered with peficitinib; however, these changes were considered not clinically relevant.

Near-Infrared 1064 nm Laser Modulates Migratory Dendritic Cells To Augment the Immune Response to Intradermal Influenza Vaccine.

Brief exposure of skin to near-infrared (NIR) laser light has been shown to augment the immune response to intradermal vaccination and thus act as an immunologic adjuvant. Although evidence indicates that the NIR laser adjuvant has the capacity to activate innate subsets including dendritic cells (DCs) in skin as conventional adjuvants do, the precise immunological mechanism by which the NIR laser adjuvant acts is largely unknown. In this study we sought to identify the cellular target of the NIR laser adjuvant by using an established mouse model of intradermal influenza vaccination and examining the alteration of responses resulting from genetic ablation of specific DC populations. We found that a continuous wave (CW) NIR laser adjuvant broadly modulates migratory DC (migDC) populations, specifically increasing and activating the Lang+ and CD11b-Lang- subsets in skin, and that the Ab responses augmented by the CW NIR laser are dependent on DC subsets expressing CCR2 and Langerin. In comparison, a pulsed wave NIR laser adjuvant showed limited effects on the migDC subsets. Our vaccination study demonstrated that the efficacy of the CW NIR laser is significantly better than that of the pulsed wave laser, indicating that the CW NIR laser offers a desirable immunostimulatory microenvironment for migDCs. These results demonstrate the unique ability of the NIR laser adjuvant to selectively target specific migDC populations in skin depending on its parameters, and highlight the importance of optimization of laser parameters for desirable immune protection induced by an NIR laser-adjuvanted vaccine.

Involvement of Reactive Metabolites of Diclofenac in Cytotoxicity in Sandwich-Cultured Rat Hepatocytes.

BACKGROUND AND OBJECTIVES: Diclofenac (DIC) is metabolized to reactive metabolites such as diclofenac acyl-ß-d-glucuronide (DIC-AG). It is possible that such reactive metabolites could cause tissue damage by formation of covalent protein adducts and other modification of cellular proteins or by induction of immune responses against its covalent protein adducts. However, the detailed mechanisms of idiosyncratic drug-induced liver injury (DILI) have been unclear. The objective is to clarify the involvement of DIC-AG and 4'hydroxydiclofenac (4'OH-DIC) in acute DILI. METHODS: We examined the effects of inhibiting DIC-AG and 4'OH-DIC production on covalent protein adduct formation and lactate dehydrogenase leakage using sandwich-cultured rat hepatocytes (SCRHs). RESULTS: After pretreatment of SCRH with (-)-borneol (BOR, a uridine diphosphate (UDP)-glucuronosyltransferase inhibitor) or sulfaphenazole (SUL, a cytochrome P450 2C9 inhibitor) for 30 minutes, intracellular concentrations of DIC, DIC-AG, and 4'OH-DIC were determined after further treating cells with 300 µM DIC for 3 hours. The decreased levels of reactive metabolites caused by BOR or SUL pretreatment resulted in decreased lactate dehydrogenase leakage from SCRH, although the formation of covalent protein adducts was not affected. CONCLUSION: These results suggested that both DIC-AG and 4'OH-DIC may be involved in acute cytotoxicity by DIC.

Effect of CYP2C19 polymorphisms on the clinical outcome of low-dose clobazam therapy in Japanese patients with epilepsy.

PURPOSE: Clobazam (CLB) is metabolized by cytochrome P450 (CYP) 3A4 to yield N-desmethylclobazam (N-CLB), which is further inactivated by CYP2C19. The aim of this study was to retrospectively evaluate the relationship between CYP2C19 polymorphisms and the efficacy of low-dose, add-on CLB therapy in Japanese patients with epilepsy. METHODS: Fifty patients were divided into three groups according to their CYP2C19 polymorphism. CLB and N-CLB serum concentrations and seizure frequency before and after starting CLB were analyzed. RESULTS: Extensive metabolizers (EMs, n=11), intermediate metabolizers (IMs, n=22), and poor metabolizers (PMs, n=17) were included. Although the dose-normalized CLB serum concentrations were not significantly different, the dose-normalized N-CLB serum concentrations were significantly higher in PMs than in EMs or IMs. Seizure frequency was significantly decreased by the CLB therapy in PMs (p<0.01), but not in EMs or IMs. CLB serum concentrations did not correlate with seizure reduction rate, but median N-CLB serum concentrations were significantly higher in patients with excellent seizure control (≧ 90 % seizure reduction) compared to those with ≧50 % seizure reduction or with <50 % seizure reduction (1103, 341, and 570 ng/mL, respectively). CONCLUSIONS: The efficacy of low-dose CLB therapy was significantly influenced by CYP2C19 polymorphisms. Ideally, CLB therapy should be started with a low dose (2.5 mg/day) and dosage increased until N-CLB serum concentration reaches 1100 ng/mL or until the desired effect is acquired, a recommendation that is particularly important for PMs.

Evolution of wheat blast resistance gene Rmg8 accompanied by differentiation of variants recognizing the powdery mildew fungus.

Wheat blast, a devastating disease having spread recently from South America to Asia and Africa, is caused by Pyricularia oryzae (synonym of Magnaporthe oryzae) pathotype Triticum, which first emerged in Brazil in 1985. Rmg8 and Rmg7, genes for resistance to wheat blast found in common wheat and tetraploid wheat, respectively, recognize the same avirulence gene, AVR-Rmg8. Here we show that an ancestral resistance gene, which had obtained an ability to recognize AVR-Rmg8 before the differentiation of Triticum and Aegilops, has expanded its target pathogens. Molecular cloning revealed that Rmg7 was an allele of Pm4, a gene for resistance to wheat powdery mildew on 2AL, whereas Rmg8 was its homoeologue on 2BL ineffective against wheat powdery mildew. Rmg8 variants with the ability to recognize AVR-Rmg8 were distributed not only in Triticum spp. but also in Aegilops speltoides, Aegilops umbellulata and Aegilops comosa. This result suggests that the origin of resistance gene(s) recognizing AVR-Rmg8 dates back to the time before differentiation of A, B, S, U and M genomes, that is, ~5 Myr before the emergence of its current target, the wheat blast fungus. Phylogenetic analyses suggested that, in the evolutionary process thereafter, some of their variants gained the ability to recognize the wheat powdery mildew fungus and evolved into genes controlling dual resistance to wheat powdery mildew and wheat blast.

Detection of 22 antiepileptic drugs by ultra-performance liquid chromatography coupled with tandem mass spectrometry applicable to routine therapeutic drug monitoring.

The purpose of this study was to develop an ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method of 22 antiepileptics for routine therapeutic monitoring. The antiepileptics used in the analyses were carbamazepine, carbamazepine-10,11-epoxide, clobazam, N-desmethylclobazam, clonazepam, diazepam, N-desmethyldiazepam, ethosuximide, felbamate, gabapentin, lamotrigine, levetiracetam, N-desmethylmesuximide, nitrazepam, phenobarbital, phenytoin, primidone, tiagabine, topiramate, valproic acid, vigabatrin and zonisamide. After protein precipitation of 50 µL plasma with methanol, the supernatant was diluted with water or was evaporated to dryness and reconstituted with mobile phase in the case of benzodiazepines. Separation was achieved on an Acquity UPLC BEH C18 column with a gradient mobile phase of 10 mm ammonium acetate containing 0.1% formic acid and methanol at a flow rate of 0.4 mL/min. An Acquity TQD instrument in multiple reaction monitoring mode with ion mode switching was used for detection. All antiepileptics were detected and quantified within 10 min, with no endogenous interference. All the calibration curves showed good linearity in the therapeutic range (r² < 0.99). The precision and accuracy values for intra- and inter-assays were within ±15% except for phenobarbital and tiagabine. A good correlation was observed between the concentration of clinical samples measured by the new method described here and the conventional methods. The values of carbamazepine and phenytoin by UPLC-MS/MS were lower than those detected by the immunoassays, which might be caused by the cross-reaction of antibodies with their metabolites. In conclusion, we developed a simple and selective UPLC-MS/MS method suitable for routine therapeutic monitoring of antiepileptics.

Exposure-response modeling of peficitinib efficacy in patients with rheumatoid arthritis.

The aim was to analyze the relationship between peficitinib exposure and efficacy response according to American College of Rheumatology (ACR) 20 criteria and 28-joint disease activity score based on C-reactive protein (DAS28-CRP) in rheumatoid arthritis (RA) patients, and to identify relevant covariates by developing exposure-response models. The analysis incorporated results from three multicenter, placebo-controlled, double-blind studies. As an exposure parameter, individual post hoc pharmacokinetic (PK) parameters were obtained from a previously constructed population PK model. Longitudinal ACR20 response rate and individual longitudinal DAS28-CRP measurements were modeled by a non-linear mixed effect model. Influential covariates were explored, and their effects on efficacy were quantitatively assessed and compared. The exposure-response models of effect of peficitinib on duration-dependent increase in ACR20 response rate and decrease in DAS28-CRP were adequately described by a continuous time Markov model and an indirect response model, respectively, with a sigmoidal Emax saturable of drug exposure in RA patients. The significant covariates were DAS28-CRP and total bilirubin at baseline for the ACR20 response model, and CRP at baseline and concomitant methotrexate treatment for the DAS28-CRP model. The covariate effects were highly consistent between the two models. Our exposure-response models of peficitinib in RA patients satisfactorily described duration-dependent improvements in ACR20 response rates and DAS28-CRP measurements, and provided consistent covariate effects. Only the ACR20 model incorporated a patient's subjective high expectations just after the start of the treatment. Therefore, due to their similarities and differences, both models may have relevant applications in the development of RA treatment. CLINICAL TRIAL REGISTRATION: NCT01649999 (RAJ1), NCT02308163 (RAJ3), NCT02305849 (RAJ4).

The Bioequivalence of Two Peficitinib Formulations, and the Effect of Food on the Pharmacokinetics of Peficitinib: Two-Way Crossover Studies of a Single Dose of 150 mg Peficitinib in Healthy Volunteers.

The marketed tablet formulation of peficitinib differs from the tablet used during the clinical trials. The bioequivalence of the marketed formulation and developmental tablet, and the food effect on the marketed formulation, were analyzed in 2 Japanese open-label, randomized, 2-way crossover studies in healthy male volunteers. Volunteers received a single oral dose of the marketed 150-mg peficitinib tablet under fasted conditions (bioequivalence), and under fed or fasted conditions (food effect). Bioequivalence was compared with the developmental 150-mg tablet. Samples for pharmacokinetic analysis were collected before dose and ≤72 hours after dose. Safety assessments included adverse events, vital signs, and laboratory variables. In total, 40 and 18 subjects were randomized to the bioequivalence and food effect studies, respectively. The 2 peficitinib formulations were bioequivalent (90% confidence intervals of the geometric mean ratios for Cmax and AUCt of peficitinib were within predefined limits of 0.8 to 1.25). The AUClast and the Cmax of the marketed tablet were 36.8% and 56.4% higher, respectively, under fed versus fasted conditions. Peficitinib was well tolerated. The marketed 150-mg tablet formulation of peficitinib was bioequivalent to the developmental 150-mg formulation, with no discernible safety differences. Bioavailability increased under fed conditions with the marketed tablet formulation.

[Influence of a liquid diet on the jaw-closing muscle spindles in growing rats].

Recently, it has been shown that prolonged feeding of a liquid diet after being weaned impedes the functional development and leads to immature mastication in growing rats. Since the jaw muscle spindles play an important role in the control of the jaw movement during the normal masticatory function, in this study we investigated the effects of prolonged feeding of a liquid diet after being weaned on the functional development of the jaw-closing muscle spindles in growing rats. Soon after weaning, 40 female Wistar rats were divided into two equal groups. The control group was fed a solid diet and the experimental group was fed a liquid diet. At 5, 7, 9 and 11 weeks, the rats were anesthetized and the response of the masseter muscle spindles to ramp-and-hold jaw stretches were recorded from the mesencephalic trigeminal nucleus. In the experimental groups, both the dynamic and the static indices were significantly lower than those of the control groups at the age of 5, 7, 9 and 11 weeks old. There was no significant change within the same group during the experimental period in both indices. These results suggest that the long-term masticatory functional change due to feeding of a liquid diet may impede the maturation of the functional properties of the jaw-closing muscle spindles, leading to immature mastication in growing rats.

Pharmacokinetics, Pharmacodynamics, and Safety of Peficitinib (ASP015K) in Healthy Male Caucasian and Japanese Subjects.

BACKGROUND AND OBJECTIVE: Peficitinib pharmacokinetics and pharmacodynamics have been characterized mainly in Caucasian subjects. This study investigated the pharmacokinetics, pharmacodynamics, safety, and tolerability of peficitinib in healthy Japanese subjects compared with Caucasian subjects. METHODS: In this single-center, randomized, double-blind, placebo-controlled study, a cohort of healthy Japanese (n = 24) and Caucasian (n = 24) men received a single oral dose of peficitinib (20, 60, or 200 mg) or placebo. Another cohort of Japanese men (n = 24) received peficitinib (10, 30, or 100 mg) or placebo twice daily for 7 days. Pharmacokinetic and pharmacodynamic parameters were assessed, and adverse events (AEs) monitored throughout. RESULTS: Dose proportionality of maximum plasma drug concentration (Cmax) and area under the plasma concentration-time curve extrapolated to infinity (AUCinf) was demonstrated for both ethnicities. The geometric mean ratio for dose-normalized Cmax was 45.7-98.8% higher and AUCinf was 33.8-66.4% higher in Japanese versus Caucasian subjects. Mean peak inhibition of STAT5 phosphorylation was higher in Japanese than Caucasian subjects for a given peficitinib dose, but inhibition was comparable across ethnicities for a given plasma peficitinib concentration. In the multiple-dose study, plasma peficitinib concentrations were similar on day 1 and day 7. All AEs were mild, and none resulted in study discontinuation. CONCLUSIONS: Peficitinib was well tolerated at doses up to 200 mg daily for 7 days in healthy Japanese subjects. Dose-proportional exposure was demonstrated across the single-dose range of 20-200 mg, with greater peficitinib exposure in Japanese compared with Caucasian subjects. The pharmacokinetic/pharmacodynamic relationships were considered comparable between these populations. CLINICALTRIALS. GOV IDENTIFIER: NCT01225224.

Pharmacokinetics and Safety of a Single Oral Dose of Peficitinib (ASP015K) in Japanese Subjects with Normal and Impaired Renal Function.

BACKGROUND AND OBJECTIVE: This study measured and compared the exposure and safety of peficitinib (ASP015K), a novel oral Janus kinase inhibitor, in subjects with normal and impaired renal function after a single oral, clinically relevant peficitinib dose. METHODS: This was an open-label, parallel-group study conducted at two centres in Japan. Subjects with normal and mildly, moderately, or severely impaired renal function received a single oral dose of peficitinib (one 150 mg tablet) under fasting conditions in a hospital setting. Blood samples were collected prior to administration and up to 72 h post-dose for pharmacokinetic assessment. Safety was assessed up to 7 days post-dose. RESULTS: Peficitinib plasma concentration-time profiles were similar between those with normal and impaired renal function. In subjects with impaired renal function, area under the plasma concentration-time curve and maximum concentration were 0.8- to 1.1-fold those in subjects with no impairment. Two subjects (one in the normal group and one in the mildly impaired group) each experienced a treatment-emergent adverse event (TEAE). There were no serious TEAEs, deaths or TEAEs leading to treatment withdrawal. CONCLUSIONS: Peficitinib exposure and TEAEs were similar in subjects with and without renal impairment after a single oral 150 mg dose. Based on these findings, it is not expected that peficitinib dose adjustment will be required in clinical practice, according to the degree of renal impairment. CLINICALTRIALS. GOV IDENTIFIER: NCT02603497.

Effects of nasal obstruction on maturation of the jaw-opening reflex in growing rats.

OBJECTIVE: Nasal obstruction during growth changes craniofacial morphology and function. However, the etiological mechanisms of these changes are unknown. The aim of the present study was to investigate the effects of nasal obstruction during growth on the maturation of the jaw-opening reflex (JOR) using an electrophysiological technique. We focused on the oral sensory receptors that regulate the activities and reflexes of the orofacial muscles. DESIGN: Sixty 6-day-old male Wistar rats were randomly divided into control and experimental groups (n = 30 each). The experimental group underwent unilateral nasal obstruction at 8 days of age. The JOR was evoked by bilateral, low-intensity electrical stimulation of the inferior alveolar nerve. The electromyographic responses were recorded bilaterally from the digastric muscles at 5, 7, and 9 weeks of age. RESULTS: The latency of the JOR was significantly longer and the peak-to-peak amplitude was significantly smaller in the experimental group than in the control group at each age, while the duration was not significantly different. Intragroup comparison of the latency, peak-to-peak amplitude, and duration at 5, 7, and 9 weeks of age revealed no significant differences in either the control or experimental groups. CONCLUSIONS: Unilateral nasal obstruction during growth may have significant effects on maturation of craniofacial function.

Functional adaptability of temporomandibular joint mechanoreceptors after an increase in the occlusal vertical dimension in rats.

OBJECTIVE: To investigate the effects of an experimentally-induced increase in the occlusal vertical dimension (iOVD) on the functional characteristics of temporomandibular joint (TMJ) mechanoreceptors in rats. MATERIALS AND METHODS: Sixty 13-week-old male albino Wistar rats were divided into control and iOVD groups (30 animals each). The vertical dimension between the maxillary and mandibular molars in the iOVD group was increased by 2.0 mm with a build-up of resin on the maxillary molars. Single-unit activities of TMJ mechanoreceptors were evoked by passive jaw movement. Recording was performed from the gasserian ganglion 1 day and 1, 3, 5, 7, and 9 weeks after the establishment of iOVD. RESULTS: Compared with the control group, the firing threshold was significantly lower at 1, 3, and 5 weeks after iOVD in the iOVD group. There were no significant differences in the firing threshold at 1 day, or 7 or 9 weeks. The maximum instantaneous firing frequency was significantly higher at 1, 3, and 5 weeks after iOVD in the iOVD group, but there were no significant differences at 1 day, or 7 or 9 weeks. There were no significant differences in the average firing frequency during the experimental period. CONCLUSIONS: The present study findings suggest that TMJ mechanoreceptors in adult rats may ultimately adapt to iOVD.

alpha-Catenin as a tension transducer that induces adherens junction development.

Adherens junctions (AJs), which are organized by adhesion proteins and the underlying actin cytoskeleton, probably sense pulling forces from adjacent cells and modulate opposing forces to maintain tissue integrity, but the regulatory mechanism remains unknown at the molecular level. Although the possibility that alpha-catenin acts as a direct linker between the membrane and the actin cytoskeleton for AJ formation and function has been minimized, here we show that alpha-catenin recruits vinculin, another main actin-binding protein of AJs, through force-dependent changes in alpha-catenin conformation. We identified regions in the alpha-catenin molecule that are required for its force-dependent binding of vinculin by introducing mutant alpha-catenin into cells and using in vitro binding assays. Fluorescence recovery after photobleaching analysis for alpha-catenin mobility and the existence of an antibody recognizing alpha-catenin in a force-dependent manner further supported the notion that alpha-catenin is a tension transducer that translates mechanical stimuli into a chemical response, resulting in AJ development.