Double-stranded RNA-induced dopaminergic neuronal loss in the substantia nigra in the presence of Mac1 receptor.

BACKGROUND: The underlying mechanism of viral infection as a risk factor for Parkinson's disease (PD), the second most common neurodegenerative disease, remains unclear. OBJECTIVE: We used Mac-1-/- and gp91phox-/- transgene animal models to investigate the mechanisms by which poly I:C, a mimic of virus double-stranded RNA, induces PD neurodegeneration. METHOD: Poly I:C was stereotaxically injected into the substantia nigra (SN) of wild-type (WT), Mac-1-knockout (Mac-1-/-) and gp91 phox-knockout (gp91 phox-/-) mice (10 µg/µl), and nigral dopaminergic neurodegeneration, α-synuclein accumulation and neuroinflammation were evaluated. RESULT: Dopaminergic neurons in the nigra and striatum were markedly reduced in WT mice after administration of poly I:C together with abundant microglial activation in the SN, and the expression of α-synuclein was also elevated. However, these pathological changes were greatly dampened in Mac-1-/- and gp91 phox-/- mice. CONCLUSIONS: Our findings demonstrated that viral infection could result in the activation of microglia as well as NADPH oxidase, which may lead to neuron loss and the development of Parkinson's-like symptoms. Mac-1 is a key receptor during this process.

Ultrafine carbon particles promote rotenone-induced dopamine neuronal loss through activating microglial NADPH oxidase.

BACKGROUND: Atmospheric ultrafine particles (UFPs) and pesticide rotenone were considered as potential environmental risk factors for Parkinson's disease (PD). However, whether and how UFPs alone and in combination with rotenone affect the pathogenesis of PD remains largely unknown. METHODS: Ultrafine carbon black (ufCB, a surrogate of UFPs) and rotenone were used individually or in combination to determine their roles in chronic dopaminergic (DA) loss in neuron-glia, and neuron-enriched, mix-glia cultures. Immunochemistry using antibody against tyrosine hydroxylase was performed to detect DA neuronal loss. Measurement of extracellular superoxide and intracellular reactive oxygen species (ROS) were performed to examine activation of NADPH oxidase. Genetic deletion and pharmacological inhibition of NADPH oxidase and MAC-1 receptor in microglia were employed to examine their role in DA neuronal loss triggered by ufCB and rotenone. RESULTS: In rodent midbrain neuron-glia cultures, ufCB and rotenone alone caused neuronal death in a dose-dependent manner. In particularly, ufCB at doses of 50 and 100µg/cm2 induced significant loss of DA neurons. More importantly, nontoxic doses of ufCB (10µg/cm2) and rotenone (2nM) induced synergistic toxicity to DA neurons. Microglial activation was essential in this process. Furthermore, superoxide production from microglial NADPH oxidase was critical in ufCB/rotenone-induced neurotoxicity. Studies in mix-glia cultures showed that ufCB treatment activated microglial NADPH oxidase to induce superoxide production. Firstly, ufCB enhanced the expression of NADPH oxidase subunits (gp91phox, p47phox and p40phox); secondly, ufCB was recognized by microglial surface MAC-1 receptor and consequently promoted rotenone-induced p47phox and p67phox translocation assembling active NADPH oxidase. CONCLUSION: ufCB and rotenone worked in synergy to activate NADPH oxidase in microglia, leading to oxidative damage to DA neurons. Our findings delineated the potential role of ultrafine particles alone and in combination with pesticide rotenone in the pathogenesis of PD.

CD11b/CD18 (Mac-1) is a novel surface receptor for extracellular double-stranded RNA to mediate cellular inflammatory responses.

During viral infection, extracellular dsRNA is a potent signaling molecule that activates many innate immune cells, including macrophages. TLR3 is a well-known receptor for extracellular dsRNA, and internalization of extracellular dsRNA is required for endosomal TLR3 activation. Preserved inflammatory responses of TLR3-deficient macrophages to extracellular dsRNA strongly support a TLR3-independent mechanism in dsRNA-mediated immune responses. The present study demonstrated that CD11b/CD18 (Mac-1 [macrophage-1 Ag]), a surface integrin receptor, recognized extracellular dsRNA and induced macrophage immune responses. CD11b deficiency reduced inflammatory cytokine induction elicited by polyinosinic:polycytidylic acid (poly I:C; a synthetic dsRNA) in mouse sera and livers, as well as in cultured peritoneal macrophages. dsRNA-binding assay and confocal immunofluorescence showed that Mac-1, especially the CD11b subunit, interacted and colocalized with poly I:C on the surface of macrophages. Further mechanistic studies revealed two distinct signaling events following dsRNA recognition by Mac-1. First, Mac-1 facilitated poly I:C internalization through the activation of PI3K signaling and enhanced TLR3-dependent activation of IRF3 in macrophages. Second, poly I:C induced activation of phagocyte NADPH oxidase in a TLR3-independent, but Mac-1-dependent, manner. Subsequently, phagocyte NADPH oxidase-derived intracellular reactive oxygen species activated MAPK and NF-κB pathways. Our results indicate that extracellular dsRNA activates Mac-1 to enhance TLR3-dependent signaling and to trigger TLR3-independent, but Mac-1-dependent, inflammatory oxidative signaling, identifying a novel mechanistic basis for macrophages to recognize extracellular dsRNA to regulate innate immune responses. This study identifies Mac-1 as a novel surface receptor for extracellular dsRNA and implicates it as a potential therapeutic target for virus-related inflammatory diseases.

The influence of community park characteristics on satisfaction in Guangzhou: Moderating and mediating effects analysis.

Community parks in old urban areas have problems such as outdated facilities and low quality, which inhibit the development of healthy aging. However, limited research has examined the correlation between such park characteristics and park satisfaction among elderly individuals. Additionally, the mechanisms underlying this association remain unclear. In this investigation, a moderated mediation framework grounded in self-determination theory was formulated to probe the interplay between these variables, with a specific focus on the mediating influence of social self-efficacy among the elderly and the moderating effect of use intention. A questionnaire survey (N = 319) was conducted in Shamian Park, Guangzhou, employing structural equation modeling for data analysis. Findings indicate that, even after controlling for demographic factors, park characteristics not only exert a direct influence on satisfaction but also exhibit an indirect impact through the mediation of social self-efficacy, with both pathways being moderated by use intention. This study has implications for how to improve the design of community parks in old urban areas in developing countries to better meet the basic needs of the elderly and promote healthy aging.

The Effect of Appearance Anxiety on Social Anxiety among College Students: Sequential Mediating Effects of Self-Efficacy and Self-Esteem.

Social anxiety is a serious psychological problem prevalent among Chinese college students, and appearance anxiety plays an important role in its development. Although some studies have explored the relationship between the two, the mediating mechanism is unclear. This study constructed a sequential mediation model based on the cognitive-behavioral theory of body image disorder and social phobia to explore the mediating role of self-efficacy and self-esteem. A total of 234 college students were recruited using the convenience sampling method, including 68 males (29.10%) and 166 females (70.90%), with an average age of 21.25 years (SD = 1.75). Data were collected using the Social Appearance Anxiety Scale, the General Self-Efficacy Scale, the Self-Esteem Scale, and the Interaction Anxiety Scale. The study's results demonstrated a significant and positive predictive relationship between appearance anxiety and social anxiety (effect = 0.21, SE = 0.04, 95% CI = [0.13, 0.29], p < 0.001). Appearance anxiety not only directly affects social anxiety but also has three indirect paths affecting social anxiety: the independent mediating effect of self-efficacy (effect = 0.03, SE = 0.01, 95% CI = [0.00, 0.06], p < 0.001), the independent mediating effect of self-esteem (effect = 0.03, SE = 0.02, 95% CI = [0.01, 0.07], p < 0.001), and the serial mediation effect of self-efficacy and self-esteem (effect = 0.01, SE = 0.01, 95% CI = [0.00, 0.03], p < 0.001). Direct and indirect effects accounted for 73.81% and 26.19% of the total effect, respectively. These findings provide new perspectives on the intervention with and treatment of social anxiety in college students.

Sensory and autonomic innervation of the local tissues at traditional acupuncture point locations GB14, ST2 and ST6.

OBJECTIVE: To visualize and compare the sensory and autonomic innervation of the local tissues at the sites of different traditional acupuncture points in the rat forehead and face by histochemical examination. METHODS: GB14 (Yangbai), ST2 (Sibai) and ST6 (Jiache) were selected as the representative traditional acupuncture points in this study, and the local tissues at these sites were dissected in rats after perfusion followed by double or triple fluorescent histochemical staining. Here, calcitonin gene-related peptide (CGRP), tyrosine hydroxylase (TH) and vesicular acetylcholine transporter (VAChT) were used to label the sensory, sympathetic and parasympathetic nerve fibers, respectively. RESULTS: The CGRP+ sensory, TH+ sympathetic and VAChT+ parasympathetic nerve fibers were simultaneously demonstrated in the local tissues at GB14, ST2 and ST6. Although the three kinds of nerve fibers ran in parallel or intermingled with each other, by the analysis from the view of three-dimensional reconstruction, it was clear that each of them distributed in an independent pattern to their corresponding target tissues including the blood vessels, hair follicles, arrector pili and subcutaneous muscles, as well as sebaceous glands. CONCLUSION: Our study demonstrated the sensory and autonomic innervation of the local tissues at GB14, ST2 and ST6, providing neurochemical evidence indicating that the CGRP+ sensory, TH+ sympathetic and VAChT+ parasympathetic nerve fibers form a neural network at these point locations that may respond to acupuncture stimulation.

Comparison of Sensory and Motor Innervation Between the Acupoints LR3 and LR8 in the Rat With Regional Anatomy and Neural Tract Tracing.

OBJECTIVE: This study aimed to investigate the sensory and motor innervation of "Taichong" (LR3) and "Ququan" (LR8) in the rat and provide an insight into the neural relationship between the different acupoints in the same meridian. METHODS: The LR3 and LR8 were selected as the representative acupoints from the Liver Meridian and examined by using the techniques of regional anatomy and neural tract tracing in this study. For both acupoints, their local nerves were observed with regional anatomy, and their sensory and motor pathways were traced using neural tract tracing with single cholera toxin subunit B (CTB) and dual Alexa Fluor 594/488 conjugates with CTB (AF594/488-CTB). RESULTS: Using the regional anatomy, the branches of the deep peroneal nerve and saphenous nerve were separately found under the LR3 and LR8. Using single CTB, the sensory neurons, transganglionic axon terminals, and motor neurons associated with both LR3 and LR8 were demonstrated on the dorsal root ganglia (DRG), spinal dorsal horn, Clarke's nucleus, gracile nucleus, and spinal ventral horn corresponding to their own spinal segments and target regions, respectively. Using dual AF594/488-CTB tracing, it was shown that the sensory and motor neurons associated with LR3 were separated from that of LR8. CONCLUSION: This study demonstrates that LR3 and LR8 are innervated by different peripheral nerves, which originated from or terminated in their corresponding spinal segments and target regions independently through the sensory and motor pathways. These results provide an example for understanding the differential innervation between the different acupoints in the same meridian.

Effects of joy and sorrow on pulse-graph parameters in healthy female college students based on emotion-evoked experiments.

OBJECTIVE: To explore the effects of joy and sorrow on pulse-graph parameters in healthy subjects and analyze their potential effect to provide preliminary evidence that pulse diagnosis can identify human emotional changes. DESIGN AND INTERVENTION: Forty healthy female college students from Beijing University of Chinese Medicine were recruited. The emotion-evoking experiment was conducted to observe the effects of joy and sorrow on pulse-graph parameters, taking neutral emotion as a control. The experiment included the following criteria. (1) Emotions evoked and evaluated: the same subjects watched three emotional videos which were, respectively, neutral, joyful and sorrowful to evoke the corresponding emotions. They completed the "subjective emotion evaluation form" (SEEF) before watching each video (T0), immediately after watching the video (T1) and 15 min after watching the video (T2) to conduct subjective emotion evaluation. Simultaneously, their heart rate, galvanic skin response and heart rate variability were collected with a 16-lead physiological recorder to conduct an objective evaluation of emotional arousal. (2) Collection of pulse-graph parameters: pulse-graph parameters of the subjects at T0, T1 and T2 were collected with a pulse condition analyzer. RESULTS: When watching the joy video, the rapid ejection phase extended significantly, both the left ventricular diastole and the cardiac cycle shortened significantly. When watching the sorrow video, the left ventricular diastole extended significantly, the cardiac cycle showed an upward trend, and heart rate showed a downward trend. CONCLUSION: Joy and sorrow have a certain effect on pulse-graph parameters of the subjects. The mechanisms may be that joy contributes to rapid ejection phase extension and a shortening of the left ventricular diastole and the cardiac cycle, while sorrow extends the left ventricular diastole. According to the theory of Traditional Chinese Medicine (TCM), the visceral functions can be mediated through human qi flow. Moderate joy and sorrow can promote, respectively, the smooth qi flow of the heart and the lung. However, excessive or long-term joy and sorrow can lead to disharmonious qi flow of the two viscera. Therefore, maintaining moderate emotions is beneficial to the physiological functions of the viscera. Great emotional fluctuations may damage the visceral functions. Future studies with effects of other emotions on pulse-graph parameters are warranted to determine the reliability of the association of emotions and pulse diagnosis.

Polydopamine-doped virus-like mesoporous silica coated reduced graphene oxide nanosheets for chemo-photothermal synergetic therapy.

Multifunctional nanocarriers have been widely accepted and utilized for biomedical applications, because of their structural regularity, convenient post-modification and controllable structure and morphology. Herein, we reported polydopamine-doped virus-like mesoporous silica coated reduced graphene oxide nanosheets (rGO@PVMSNs) nanocomposites by a facile oil-water biphase stratification method. The synthesized rGO@PVMSNs nanocomposites performed excellent biocompatibility and photothermal performance. They could be employed as photoacoustic imaging contrast in vivo. Furthermore, the rGO@PVMSNs nanocarriers were used for loading the antitumor drug doxorubicin (DOX), the rGO@PVMSNs@DOX nanocomposites were also demonstrated to be with high inhibition of HepG2 cancer cells, especially with the help of near-infrared irradiation, which were more efficient than single chemotherapy or photothermal therapy. The rGO@PVMSNs@DOX nanocomposites of this work could be used as photoacoustic imaging and chemo-photothermal synergetic therapy agents, which show a new perspective for clinical tumor diagnosis and therapy.

Experiences and views of people with diabetes during Ramadan fasting: A qualitative meta-synthesis.

OBJECTIVES: To review and appraise the existing qualitative studies on Ramadan fasting in participants with diabetes and to integrate valuable qualitative evidence for optimizing diabetes management. METHODS: Twelve databases (PubMed, Embase, Cochrane Library, Science Direct, CINAHL, PsycINFO, JBI (Joanna Briggs institute), Web of Science, and four Chinese databases) were searched to identify qualitative studies on experiences and perspectives of Ramadan fasting in participants with diabetes. CASP (Critical Appraisal Skills Program) Qualitative Checklists were applied to appraise the included studies. A meta-synthesis approach was used to analyze the included studies. Through the strategy of inductive thematic synthesis and reciprocal interpretation, the findings and quotations of the included studies were integrated into new themes and categories. The CERQual (Confidence in the Evidence from Reviews of Qualitative Research) tool was used to grade the confidence of the new themes. RESULTS: A total of 11 qualitative studies were included, and 43 findings were isolated. Ten new themes were identified and synthesized from the findings. Finally, four new categories were integrated, including the knowledge and understanding of observing Ramadan fasting, well-being and challenges, self-efficacy, and needs and expectations of participants with diabetes during Ramadan. CONCLUSIONS: Insulin-dependent individuals call for special concern during Ramadan fasting. Ramadan-focused education needs to be developed and generalized, and existing guidelines should be improved to optimize the management of diabetes. Professional HCPs contribute to weigh the health risks and mental satisfaction for their patients, partly, to balance health and religion. Participants' psychological construction is another concern for religious scholars and psychologists.

Single-molecule study of lateral mobility of epidermal growth factor receptor 2/HER2 on activation.

The transmembrane protein HER2, a member of the epidermal growth factor receptor family of tyrosine kinase, plays important roles in many fundamental cellular processes as well as the pathogenesis of many cancers. In this work, we have applied the single-molecule fluorescence microscopic method to study lateral mobility change of HER2 on activation by imaging and tracking individual GFP-tagged HER2 molecules on the membrane of living cells. The single HER2 molecules displayed different diffusion rates and modes. It was interesting to find that the mobility of HER2 increased upon stimulation by heregulin beta1, the specific ligand of HER3. The faster diffusion was related to the tyrosine phosphorylation of HER2 or EGFR. The results provided new information for the understanding of HER2 activation and molecular mechanism of signal transduction through HER2/HER3 heterodimerization.

A study on the fundamental factors determining the efficacy of siRNAs with high C/G contents.

Although there are many reports about the efficacy of siRNAs, it is not clear whether those siRNAs with high C/G contents can be used to silence their target mRNAs efficiently. In this study, we investigated the structure and function of a group of siRNAs with high C/G contents. The results showed that single siRNAs against the Calpain, Otoferlin and Her2 mRNAs could induce different silencing effects on their targets, suggesting that the accessibility to target sequences influences the efficacy of siRNA. Unexpectedly, a single siRNA could target its cognate sequence in the 3'UTR of EEF1D or the 5'UTR of hTRF2 or CDC6. Their interaction induced different modes of gene silencing. Furthermore, the introduction of mutations into the 3' end of the passenger strand showed that the position and number of mutated nucleotides could exert some influence on the efficacy of siRNA. However, these mutations did not completely block the passenger strand from exerting its RNAi effect. Interestingly, our findings also indicated that the target mRNA might play essential roles in maintaining or discarding the guide strand in RISCs. Thus, the conclusion could be drawn that favorable siRNA sequences, accessible target structures and the fast cleavage mode are necessary and sufficient prerequisites for efficient RNAi.

Association between B vitamins and schizophrenia: A population-based case-control study.

To explore the association between schizophrenia and six types of B vitamins, including choline, biotin, riboflavin, pyridoxamine, pyridoxine and nicotinamide, based on the hydrophilic interaction liquid chromatography column (HILIC) Liquid Chromatography-Mass Spectrometry (LC-MS) platform. We conducted the case-control study between November 2015 and September 2016 in Weifang, Shandong Province, China. Blood samples from 128 cases of schizophrenia and 101 controls were collected, and B vitamin were measured by LC-MS coupled with HILIC. The HILIC UPLC-MS based analysis of serum B vitamins levels from 128 cases (30 cases with first-episode, 98 cases with relapse) and 101 controls were performed. The results indicated that lower pyridoxine level and schizophrenia was related. (total cases versus controls: ß= -0.215, 95% CI: -0.271, -0.125, p < 0.001; first-episode cases versus controls: ß = -0.190, 95% CI: -0.277, -0.103, p < 0.001). Higher nicotinamide level was also associated with schizophrenia after adjusting confounders (ß = 0.343, 95% CI: 0.022, 0.664, p = 0.036). Other four B vitamins, including biotin, riboflavin, pridoxamine and choline, were showed no statistically difference in cases versus controls, first episode cases versus relapse cases. Two types of B Vitamins, pyridoxine and nicotinamide, show significant association with the schizophrenia.

The ubiquitin ligase MuRF1 regulates PPARα activity in the heart by enhancing nuclear export via monoubiquitination.

The transcriptional regulation of peroxisome proliferator-activated receptor (PPAR) α by post-translational modification, such as ubiquitin, has not been described. We report here for the first time an ubiquitin ligase (muscle ring finger-1/MuRF1) that inhibits fatty acid oxidation by inhibiting PPARα, but not PPARß/δ or PPARγ in cardiomyocytes in vitro. Similarly, MuRF1 Tg+ hearts showed significant decreases in nuclear PPARα activity and acyl-carnitine intermediates, while MuRF1-/- hearts exhibited increased PPARα activity and acyl-carnitine intermediates. MuRF1 directly interacts with PPARα, mono-ubiquitinates it, and targets it for nuclear export to inhibit fatty acid oxidation in a proteasome independent manner. We then identified a previously undescribed nuclear export sequence in PPARα, along with three specific lysines (292, 310, 388) required for MuRF1's targeting of nuclear export. These studies identify the role of ubiquitination in regulating cardiac PPARα, including the ubiquitin ligase that may be responsible for this critical regulation of cardiac metabolism in heart failure.

Completion of the life cycle of Sarcocystis zuoi , a parasite from the Norway rat, Rattus norvegicus.

Transmission experiments were performed to elucidate the life cycle of Sarcocystis zuoi found in Norway rats ( Rattus norvegicus ) in China. Two king rat snakes ( Elaphe carinata ) fed sarcocysts from the muscles of 4 naturally infected Norway rats shed sporocysts measuring 10.8 ± 0.7 × 8.0 ± 0.7 µm, with a prepatent period of 8-9 days. Sporocysts from the intestine of 2 experimentally infected king rat snakes were given to the laboratory Sprague-Dawley (SD) rats ( R. norvegicus ) and Kunming (KM) mice ( Mus musculus ). Microscopic sarcocysts developed in the skeletal muscles of SD rats. No sarcocysts were observed in KM mice. Characters of ultrastructure and molecule of sarcocysts from SD rats were confirmed as S. zuoi . Our results indicate that king rat snake is the definitive host of S. zuoi .

Identification of Sarcocystis cymruensis in wild Rattus flavipectus and Rattus norvegicus from Peoples Republic of China and its transmission to rats and cats.

Sarcocystis cymruensis was initially identified in skeletal muscles of 22 (11.6%) of 189 wild rats (Rattus spp.) captured in 2008 in Anning and Kunming, Peoples Republic of China. Sarcocyst walls were thin (<1 µm) and smooth. Ultrastructurally, the parasitophorous vacuolar membrane had small, osmiophilic knob-like invaginations covered with numerous vesicle-like invaginations toward the interior of the cyst. Domestic cats (Felis catus) fed sarcocysts shed sporocysts measuring 10.3 (9.8-11.0) × 7.6 (7.2-9.5) µm with a prepatent period of 6 to 8 days. Sarcocysts were infective orally to Norway rats, and oocysts and sporocysts developed in the lamina propria of the small intestine of rats fed sarcocysts. Thus, rats were both intermediate and definitive hosts for S. cymruensis.

Inosine-containing RNA is a novel innate immune recognition element and reduces RSV infection.

During viral infections, single- and double-stranded RNA (ssRNA and dsRNA) are recognized by the host and induce innate immune responses. The cellular enzyme ADAR-1 (adenosine deaminase acting on RNA-1) activation in virally infected cells leads to presence of inosine-containing RNA (Ino-RNA). Here we report that ss-Ino-RNA is a novel viral recognition element. We synthesized unmodified ssRNA and ssRNA that had 6% to16% inosine residues. The results showed that in primary human cells, or in mice, 10% ss-Ino-RNA rapidly and potently induced a significant increase in inflammatory cytokines, such as interferon (IFN)-ß (35 fold), tumor necrosis factor (TNF)-α (9.7 fold), and interleukin (IL)-6 (11.3 fold) (p<0.01). Flow cytometry data revealed a corresponding 4-fold increase in influx of neutrophils into the lungs by ss-Ino-RNA treatment. In our in vitro experiments, treatment of epithelial cells with ss-Ino-RNA reduced replication of respiratory syncytial virus (RSV). Interestingly, RNA structural analysis showed that ss-Ino-RNA had increased formation of secondary structures. Our data further revealed that extracellular ss-Ino-RNA was taken up by scavenger receptor class-A (SR-A) which activated downstream MAP Kinase pathways through Toll-like receptor 3 (TLR3) and dsRNA-activated protein kinase (PKR). Our data suggests that ss-Ino-RNA is an as yet undescribed virus-associated innate immune stimulus.

Heregulinbeta activates store-operated Ca2+ channels through c-erbB2 receptor level-dependent pathway in human breast cancer cells.

The heregulinbeta (HRGbeta) is a ligand to activate c-erbB2/c-erbB3 interaction and can subsequently increases cytosolic [Ca(2+)](i). In the two human breast cancer cell lines, MCF-7 shows a low c-erbB2 expression level, whereas SK-BR-3 overexpress c-erbB2 receptor. In this article, we have found that in MCF-7, HRGbeta induced Ca(2+) release from the endoplasmic reticulums (ER) and subsequently activated Ca(2+) entry via store-operated Ca(2+) channel (SOC). However, in SK-BR-3, HRGbeta failed to induce Ca(2+) release and Ca(2+)entry. RNA interference to decrease c-erbB2 level in SK-BR-3 resulted in reactivation of HRGbeta-evoked Ca(2+) release and Ca(2+) entry via SOC, which was similar to that of MCF-7. In addition, in the absence of HRGbeta, a constitutive activation of SOC was observed in SK-BR-3 rather than in MCF-7 and c-erbB2-siRNA treated SK-BR-3. Compared to the cells with low c-erbB2 level, c-erbB2 might tend to interact with c-erbB3 in the resting state in the cells with high c-erbB2 level, which resulted in different [Ca(2+)](i) responses to HRGbeta. In SK-BR-3, the Ca(2+) mobilization in the presence or in the absence of HRGbeta was completely blocked by PLC inhibitor U73122. In summary, our results indicate that HRGbeta-induced SOC was regulated by c-erbB2 level and dependent on activation of PLC in human breast cancer cells.