The relationships between leader emotional intelligence, transformational leadership, and transactional leadership and job performance: A mediator model of trust

This study utilized the hierarchical linear model and trust as a mediator; designated leader emotional intelligence as a team-level dimension; and designated transformational leadership, transactional leadership, and trust in supervisor as individual-level dimensions. An analysis was performed to explore the relationships between these individual- and team-level variables and the job performance of real estate brokers, as well as the potential role of trust-oriented leadership as a mediator for the relationships between leader emotional intelligence, transformational leadership, and transactional leadership and individual job performance. The empirical results revealed that leader emotional intelligence, transformational leadership, and transactional leadership had direct, significant, and positive relationships with individual job performance. Furthermore, it was also discovered that, with trust in supervisor serving as a mediator, these three variables also had indirect, significant, and positive relationships with employee job performance.

The Impact of Living Arrangements and Social Capital on the Well-Being of the Elderly

This study examines the impact of living arrangements and social capital on the subjective well-being of the elderly, as well as the mutual effects and relationships between the well-being and self-rated health status of the elderly. A total of 369 questionnaires were administered, and the effective recovery rate was 98.10%. The results indicate three key findings: (1) the current location for aging in place, social support, social activities, house ownership, and self-rated health status are indispensable factors affecting the well-being of the elderly. The best location for aging in place was the community, where the elderly's sense of well-being was highest-the next best options were aging at home and institutional care. (2) Elderly people with sole ownership of their homes were more likely to have higher levels of well-being than those owning jointly or who were tenants. (3) There was significant interaction between subjective well-being and self-rated health status.

IMPACTS OF SOCIAL CAPITAL ON HOUSING PRICES: THE CASE OF SPECIAL RELATIONSHIP-BASED TRANSACTIONS

In Taiwan, many housing transactions are special relationship-based transactions that involve family and friends, debt relations, urgent purchases and sales, and government agencies. As such, the prices in such transactions should differ from those in what we consider to be normal arm’s length transactions. In this regard, social capital theory can be used to analyze these transactions. The empirical data on housing transactions conducted in Taipei City from January 1, 2012 to December 31, 2018 were collected for this study. The empirical results showed that the prices in transactions involving debt relations and urgent purchases and sales were 22.6% lower than those in normal arm’s length transactions. The prices in transactions with government agencies were 48.9% lower than those in normal arm’s length transactions. The prices in transactions with first-degree, second-degree, and third-degree relatives were respectively, 57.3%, 53.1%, and 50.3% lower than those in normal arm’s length transactions. The prices in transactions involving friends were 28.0% lower than those in normal arm’s length transactions. The empirical results highlight the importance of the impacts of personal relationships or social relations on housing prices in special relationship-based transactions. The results also supported the social capital hypothesis.

The influence of real estate brokers' personalities, psychological empowerment, social capital, and knowledge sharing on their innovation performance: The moderating effect of moral hazard

This study proposed and examined a conceptual framework on the influence of real estate brokers' personalities, psychological empowerment, social capital, and knowledge sharing on their innovation performance, and used moral hazard as a moderating variable. We used structural equation modeling (SEM) for data analysis and estimation. The participants were real estate brokers in Kaohsiung City. A total of 1,000 questionnaires were administered to 100 branch offices of real estate companies, 571 of which were later recovered from 80 branch offices. After removing 52 for being invalid, we were left with 519 valid questionnaires, indicating a 51.9% recovery rate. The empirical results suggest that the real estate brokers' personalities and psychological empowerment positively and significantly influence social capital; personality and psychological empowerment also positively and significantly influence their innovation performance; and social capital significantly influences knowledge sharing, which in turn positively and significantly influences the brokers' innovation performance. In environments with higher levels of moral hazard, the influence of social capital on the brokers' knowledge sharing is significantly diminished.

THE IMPACTS OF TASK COMPLEXITY, OVERCONFIDENCE, CONFIRMATION BIAS, CUSTOMER INFLUENCE, AND ANCHORING ON VARIATIONS IN REAL ESTATE VALUATIONS

Real estate valuation relies on real estate appraisers’ accurate assessments, which reflects the need to improve the objectivity of the valuation process. From the perspective of behavioral economics, appraisers are prone to numerous behavioral conflicts that could result in variations in their valuations. This study investigates the impacts of task complexity, overconfidence, confirmation bias, client influence, and anchoring on variations in real estate valuations. An online questionnaire was administered to 272 members of the Taiwan Real Estate Appraisers Association LINE group. Structural equation modeling was employed for analysis. A total of 150 valid responses were collected, yielding a valid response rate of 55.15%. The empirical results revealed that cognitive bias and client influence have significant and positive impacts on anchoring. Task complexity, overconfidence, and customer influence have significant and positive impacts on valuation variation. In addition to being the first study to explore the relationship between task complexity and valuation variation, this study also explored unconventional issues, such as the relationships between overconfidence, confirmation bias, and valuation variation. The results highlight the salience and value of behavioral economics-based analyses in empirical research on real estate valuation.

THE IMPACT OF URBAN RENEWAL ON NEIGHBORING HOUSING PRICES: AN APPLICATION OF HIERARCHICAL LINEAR MODELING

This study explored the impacts of urban renewal projects on neighboring housing prices. Hierarchical linear modeling (HLM) was employed to analyze urban renewal projects in Taipei City. The Level 1 independent variables pertained to a house itself (19,157 pieces of data), such as its structure and neighborhood attributes. The Level 2 variable pertained to an urban renewal project (23 cases of urban renewal), and the explanatory variable was the scale of each urban renewal project. The study examined whether differences exist between the impacts of various urban renewal projects on neighboring housing prices, and analyzed the extent to which the differences in neighboring housing prices are caused by the differences between urban renewal projects. The empirical results showed that the mean housing price varies significantly between each urban renewal project. In regard to the variance in the mean house price, 31.46% was caused by the differences between the urban renewal projects. The estimated coefficient of the grand floor area of urban renewal (FLAREA) had a positive value and attained a 1% level of significance. This indicates that the larger the scale of an urban renewal project, the larger its effects on neighboring housing prices. The empirical results of this study could better explain the impacts of the scale of an urban renewal project on the externalities of urban renewal.

THE INFLUENCE OF THE TECHNICAL DIMENSION, FUNCTIONAL DIMENSION, AND TENANT SATISFACTION ON TENANT LOYALTY: AN ANALYSIS BASED ON THE THEORY OF PLANNED BEHAVIOR

This study primarily explored the influence of the technical dimension, functional dimension, and tenant satisfaction on tenant loyalty. The theory of planned behavior served as the basis of this study, and the three aforementioned factors (the technical dimension, the functional dimension, and tenant satisfaction) were incorporated into a conceptual framework for tenant loyalty. Structural equation modeling (SEM) was employed for parameter estimation. The participants consisted of tenants residing in eight administrative districts in Kaohsiung City. 315 questionnaires were administered, all of which were returned. After removing 15 invalid responses, there were 300 valid responses, which indicated an effective recovery rate of 95.2%. The results showed that the technical dimension, the functional dimension, and attitude significantly and positively influenced tenant satisfaction. Tenant satisfaction, perceived behavioral control, and social norms significantly and positively influenced tenant loyalty. Tenant satisfaction mediated the influence of the technical dimension and the functional dimension on tenant loyalty; the mediating effect of the functional dimension on tenant loyalty was greater than that of the technical dimension. The findings of this study highlight the measures rental companies should adopt in order to enhance the technical dimension, functional dimension, and tenant satisfaction, as this is crucial to maintaining sustainable operations.

THE IMPACT OF LUXURY HOUSING ON NEIGHBORHOOD HOUSING PRICES: AN APPLICATION OF THE SPATIAL DIFFERENCE-IN-DIFFERENCES METHOD

This study investigated the spatial spillover effects of luxury housing during and after construction, in regards to increases in housing prices in neighboring areas as well as the spatial dependence of neighboring housing. This study focused on already completed luxury housing in Taipei, Taiwan. First, the nearest-neighbor matching approach of propensity score matching was used to overcome the problem of data heterogeneity. The difference-in-differences (DD) method and spatial econometrics were used for analysis. The empirical results indicated that the spatial error model had the best goodness of fit. This indicated that housing prices increased by 13.0% during construction of luxury housing nearby. This indicated that housing prices increased by 5.8% after the construction of luxury housing nearby. The empirical results showed that the ongoing and completed construction of luxury housing had spillover effects on housing prices. The effect of ongoing construction of luxury housing was particularly large in scope, indicating its role as a predictor of psychological reaction in the market.

Exploring the Factors Influencing Kaohsiung Residents' Intentions to Choose Age-Friendly Housing

Taiwan’s declining birthrate has changed the housing market, which should become more consumer-oriented in the future. In particular, age-friendly housing has become a salient housing choice among buyers. Age-friendly housing consists of housing units that are suitable for occupants of any age. There are three concepts underlying such housing: aging in place, multigenerational-multiunit living arrangements, and lifetime homes. This study aimed to examine the factors affecting consumers’ choice of age-friendly housing. The participants were residents of Kaohsiung City, and data analysis was performed using a binary logistic model. The empirical results indicated that adult sons/daughters, residents who currently live in the city center, residents who have a high or medium monthly family income, residents who are currently part of a stem family, residents who desire to live under multigenerational-multiunit living arrangements, residents who desire to be a part of a stem family, and residents who prioritize housing type when house-buying are significantly more likely to choose age-friendly housing. These results can serve as a reference regarding age-friendly housing investments for investors, as well as for house buyers who are deliberating between age-friendly housing and ordinary housing.

M(1)-like muscarinic acetylcholine receptors regulate fast-spiking interneuron excitability in rat dentate gyrus

Cholinergic transmission through muscarinic acetylcholine receptors (mAChRs) plays a key role in cortical oscillations. Although fast-spiking (FS), parvalbumin-expressing basket cells (BCs) are proposed to be the cellular substrates of gamma oscillations, previous studies reported that FS nonpyramidal cells in neocortical areas are unresponsive to cholinergic modulation. Dentate gyrus (DG) is an independent gamma oscillator in the hippocampal formation. However, in contrast to other cortical regions, the direct impact of mAChR activation on FS BC excitability in this area has not been investigated. Here, we show that bath-applied muscarine or carbachol, two mAChR agonists, depolarize DG BCs in the acute brain slices, leading to action potential firing in the theta-gamma bands in the presence of blockers of ionotropic glutamate and gamma-aminobutyric acid type A receptors at physiological temperatures. The depolarizing action persists in the presence of tetrodotoxin, a voltage-gated Na(+) channel blocker. In voltage-clamp recordings, muscarine markedly reduces background K(+) currents. These effects are mimicked by oxotremorine methiodide, an mAChR-specific agonist, and largely reversed by atropine, a non-selective mAChR antagonist, or pirenzepine, an M(1) receptor antagonist, but not by gallamine, an M(2/4) receptor antagonist. Interestingly, in contrast to M(1)-receptor-mediated depolarization, M(2) receptor activation by the specific agonist arecaidine but-2-ynyl ester tosylate down-regulates GABA release at BC axons-the effect is occluded by gallamine, an M(2) receptor antagonist. Overall, muscarinic activation results in a net increase in phasic inhibitory output to the target cells. Thus, cholinergic activation through M(1)-like receptor enhances BC activity and promotes the generation of nested theta and gamma rhythms, thereby enhancing hippocampal function and associated performance.

Critical roles of TRAF2 and TRAF5 in tumor necrosis factor-induced NF-kappa B activation and protection from cell death

Tumor necrosis factor (TNF) receptor-associated factors (TRAFs) were identified as signal transducers for the TNF receptor superfamily. However, the exact roles of TRAF2 and TRAF5 in TNF-induced NF-kappaB activation still remain controversial. To address this issue, we generated TRAF2 and TRAF5 double knockout (DKO) mice. TNF- but not interleukin-1-induced nuclear translocation of NF-kappaB was severely impaired in murine embryonic fibroblasts (MEFs) derived from DKO mice. Moreover, DKO MEFs were more susceptible to TNF-induced cytotoxicity than TRAF2 knockout MEFs. Collectively, these results indicate that both TRAF2 and TRAF5 are involved in TNF-induced NF-kappaB activation and protection from cell death.

FADD Null Mouse Embryonic Fibroblasts Undergo Apoptosis after Photosensitization with the Silicon Phthalocyanine Pc 4

Oxidative stress, such as photodynamic therapy with the silicon phthalocyanine Pc 4 (Pc 4-PDT), can induce apoptosis and tumor necrosis factor alpha (TNF) production. TNF receptors, as well as other death receptors, have been implicated in stress-induced apoptosis. To assess directly the role of FADD, a death receptor-associated protein, in induction of apoptosis post-Pc 4-PDT, embryonic fibroblasts from FADD knock out (k/o) and wild-type (wt) mice were used. Pc 4-PDT induced casp-3 activation and apoptosis in both cell types. In the presence of zVAD, a pancaspase inhibitor, Pc 4-PDT-induced apoptosis was abrogated in both cell lines. Fumonisin B1 (FB), an inhibitor of ceramide synthase, had no effect on apoptosis after Pc 4-PDT in either cell line. Similar to Pc 4-PDT, exogenous C6-ceramide bypassed FADD deficiency and induced zVAD-sensitive apoptosis. In contrast to Pc 4 photosensitization, TNF did not induce either apoptosis or ceramide accumulation in FADD k/o cells. In the absence of FADD deficiency, TNF-induced apoptosis was zVAD-sensitive and FB-insensitive. Induced ceramide levels remained elevated after cotreatment with TNF and zVAD in FADD wt cells. Taken together, these data provide genetic evidence for a lack of FADD requirement in Pc 4-PDT- or C6-ceramide-induced apoptosis. FB-sensitive ceramide production accompanies, but does not suffice, for apoptosis after Pc 4 photosensitization or TNF.

Tumor necrosis factor receptor-associated factor 6 (TRAF6) deficiency results in exencephaly and is required for apoptosis within the developing CNS

Tumor necrosis factor receptor-associated factors (TRAFs) are adaptor proteins important in mediating intracellular signaling. We report here that targeted deletion of traf6 greatly increases the frequency of failure of neural tube closure and exencephaly in traf6 (-/-) mice. The penetrance of this defect is influenced by genetic background. Neural tube fusion requires the coordination of several biological processes, including cell migration invoked by contact-dependent signaling, cell proliferation, and programmed cell death (PCD). To gain greater insight into the role of TRAF6 in these processes, neural development and migration within the CNS of traf6 (-/-) mice and controls were assessed through temporal examination of a number of immunohistochemical markers. In addition, relative levels of cellular proliferation and PCD were examined throughout embryonic development using bromodeoxyuridine (BrdU) and in situ terminal deoxynucleotidyl transferase-mediated dUTP biotinylated nick end labeling (TUNEL), respectively. The data suggest that loss of TRAF6 does not significantly alter the level of cellular proliferation or the pattern of neural differentiation per se, but rather regulates the level of PCD within specific regions of the developing CNS. Substantial reductions in TUNEL were observed within the ventral diencephalon and mesencephalon in exencephalic traf6 (-/-) embryos. Our results demonstrate a novel and prominent role for TRAF6 in the regional control of PCD within the developing CNS.

Deficiency of T2K leads to apoptotic liver degeneration and impaired NF-kappaB-dependent gene transcription

Induction of NF-kappaB-dependent transcription requires phosphorylation and subsequent degradation of I-kappaB, an inhibitor of NF-kappaB, followed by nuclear translocation and DNA binding of NF-kappaB. Tumor necrosis factor receptor-associated factor 2 (TRAF2) plays a role in NF-kappaB activation in response to cytokines such as tumor necrosis factor alpha (TNFalpha). In this study, we purified and characterized a novel kinase (T2K, also known as TBK1 or NAK), which associates with TRAF2 and exhibits kinase activity towards I-kappaBalpha in vitro. The physiological function of T2K was investigated using T2K-deficient mice. Heterozygotes appear normal, but t2k(-/-) animals die at approximately E14.5 of massive liver degeneration and apoptosis. Never theless, hematopoietic progenitors from T2K-deficient fetal liver support normal lymphocyte development. Furthermore, t2k(-/-) embryonic fibroblasts and thymocytes do not display increased sensitivity to TNFalpha-induced apoptosis. In response to either TNFalpha or IL-1 induction, t2k(-/-) embryonic fibroblasts exhibit normal degradation of I-kappaB and kappaB-binding activity. However, NF-kappaB-directed transcription is dramatically reduced. These results demonstrate that, like I-kappaB kinase beta and the RelA subunit of NF-kappaB, T2K is critical in protecting embryonic liver from apoptosis. However, T2K has a unique role in the activation of NF-kappaB-directed transcription, apparently independent of I-kappaB degradation and NF-kappaB DNA binding.

Low frequency of bacteremia after endoscopic mucosal resection

BACKGROUND

Endoscopic mucosal resection has become a popular alternative for the treatment of early-stage neoplasia of the gastrointestinal tract. However, there are still no data on the frequency of bacteremia associated with this form of treatment.

METHODS

We conducted a prospective study of 21 men and 17 women undergoing endoscopic mucosal resection with a cap-fitted panendoscope for upper gastrointestinal lesions. Blood cultures were performed before, 10 minutes after, and 4 hours after the procedure for both aerobic and anaerobic bacteria.

RESULTS

Blood culture at baseline was negative in all the patients. Two of 38 patients (5.3 %) had positive blood culture at 10 minutes after the procedure. The isolated microorganisms were Streptococcus salivarius and Corynebacterium species. All patients had negative blood cultures 4 hours later. None of these 38 patients had any symptoms or signs associated with infection.

CONCLUSIONS

Bacteremia associated with endoscopic mucosal resection is infrequent and transient.

Requirement for Casper (c-FLIP) in regulation of death receptor-induced apoptosis and embryonic development

Casper (c-FLIP) associates with FADD and caspase-8 in signaling complexes downstream of death receptors like Fas. We generated Casper-deficient mice and cells and noted a duality in the physiological functions of this molecule. casper-/- embryos do not survive past day 10.5 of embryogenesis and exhibit impaired heart development. This phenotype is reminiscent of that reported for FADD-/- and caspase-8-/- embryos. However, unlike FADD-/- and caspase-8-/- cells, casper-/- embryonic fibroblasts are highly sensitive to FasL- or TNF-induced apoptosis and show rapid induction of caspase activities. NF-kappaB and JNK/SAPK activation is intact in TNF-stimulated casper-/- cells. These results suggest that Casper has two distinct roles: to cooperate with FADD and caspase-8 during embryonic development and to mediate cytoprotection against death factor-induced apoptosis.

Severe liver degeneration and lack of NF-kappaB activation in NEMO/IKKgamma-deficient mice

Phosphorylation of IkappaB, an inhibitor of NF-kappaB, is an important step in the activation of the transcription factor NF-kappaB. Phosphorylation is mediated by the IkappaB kinase (IKK) complex, known to contain two catalytic subunits: IKKalpha and IKKbeta. A novel, noncatalytic component of this kinase complex called NEMO (NF-kappaB essential modulator)/IKKgamma was identified recently. We have generated NEMO/IKKgamma-deficient mice by gene targeting. Mutant embryos die at E12.5-E13.0 from severe liver damage due to apoptosis. NEMO/IKKgamma-deficient primary murine embryonic fibroblasts (MEFs) lack detectable NF-kappaB DNA-binding activity in response to TNFalpha, IL-1, LPS, and Poly(IC) and do not show stimulus-dependent IkappaB kinase activity, which correlates with a lack of phosphorylation and degradation of IkappaBalpha. Consistent with these data, mutant MEFs show increased sensitivity to TNFalpha-induced apoptosis. Our data provide in vivo evidence that NEMO/IKKgamma is the first essential, noncatalytic component of the IKK complex.

Mediation of TNF receptor-associated factor effector functions by apoptosis signal-regulating kinase-1 (ASK1)

Tumor necrosis factor-alpha (TNF), a major inflammatory cytokine, generates a wide variety of cellular responses via key cytoplasmic adaptor molecules named TNF receptor-associated factors (TRAFs). We report that TRAF2, TRAF5 and TRAF6 associate with apoptosis signal-regulating kinase 1 (ASK1), and a catalytically-inactive ASK1 mutant blocks stress-activated protein kinase (SAPK)/Jun NH2-terminal kinase (JNK) activation by these TRAFs. A truncated derivative of TRAF2, which inhibits SAPK activation by TNF, blocks TNF-induced ASK1 activation. Furthermore, protection from TNF-induced cell death conferred by an ASK1 mutant is dependent upon TRAF2. Hence, ASK1 is a common mediator of TRAF-regulated SAPK and apoptosis signaling, and the TRAF2 - ASK1 connection completes the signaling cascade from TNF to SAPK/JNK activation.

TRAF2 deficiency results in hyperactivity of certain TNFR1 signals and impairment of CD40-mediated responses

Tumor necrosis factor (TNF) receptor-associated factor 2 (TRAF2) can interact with various members of the TNF receptor family. Previously, we reported that TRAF2-deficient mice die prematurely and have elevated serum TNF levels. In this study, we demonstrate that TRAF2-deficient macrophages produce increased amounts of nitric oxide (NO) and TNF in response to TNF stimulation. Furthermore, we could enhance the survival of TRAF2-deficient mice by eliminating either TNF or TNFR1. Using these double-knockout mice, we show that in the absence of TRAF2, the T helper-dependent antibody response, CD40-mediated proliferation, and NF-kappaB activation are defective. These data demonstrate two important roles of TRAF2, one as a negative regulator of certain TNFR1 signals and the other as a positive mediator of CD40 signaling.

Interleukin 13 is secreted by and stimulates the growth of Hodgkin and Reed-Sternberg cells

Gene expression patterns can provide vital clues to the pathogenesis of neoplastic diseases. We investigated the expression of 950 genes in Hodgkin's disease (HD) by analyzing differential mRNA expression using microarrays. In two independent microarray experiments, the HD-derived cell lines L428 and KMH2 were compared with an Epstein-Barr virus (EBV)-immortalized lymphoblastoid B cell line, LCL-GK. Interleukin (IL)-13 and IL-5 were found to be highly expressed in the HD-derived cell lines. Examination of IL-13 and IL-5 expression by Northern blot analysis and enzyme-linked immunosorbent assay confirmed these results and revealed the expression of IL-13 in a third HD-derived cell line, HDLM2. Control LCL and EBV-negative non-Hodgkin lymphoma-derived cell lines did not express IL-13. In situ hybridization of lymph node tissue from HD patients showed that elevated levels of IL-13 were specifically expressed by Hodgkin/Reed-Sternberg (H/RS) tumor cells. Treatment of a HD-derived cell line with a neutralizing antibody to IL-13 resulted in a dose-dependent inhibition of H/RS cell proliferation. These data suggest that H/RS cells produce IL-13 and that IL-13 plays an important role in the stimulation of H/RS cell growth, possibly by an autocrine mechanism. Modulation of the IL-13 signaling pathway may be a logical objective for future therapeutic strategies.

Gene targeting in the analysis of mammalian apoptosis and TNF receptor superfamily signaling

Apoptosis, or programmed cell death (PCD), is the subject of much current investigative interest. Developing embryos and many adult organ systems require the tight coupling of cellular proliferation and PCD to ensure proper organogenesis and optimal tissue function. Over the past decade, our knowledge of the genetic basis underlying the execution of apoptosis in mammals has progressed enormously, thanks largely to groundbreaking studies performed in the nematode Caenorhabditis elegans. In contrast, the components of the signaling apparatus that links the various death stimuli and the receptors they stimulate to the execution mechanism remain relatively unknown. It is only in the past 4 years that studies of signal transduction via members of the tumor necrosis factor (TNF) receptor superfamily have identified a plethora of novel signaling proteins, including molecules that are directly involved in apoptosis signaling, and others that regulate the induction of cell death. This two-part review focuses on the biology of apoptosis and signaling through members of the TNF receptor superfamily as revealed by the study of gene-targeted "knockout" mice. These genetic mutant animals are invaluable tools not only for confirming or refuting a proposed function of a particular gene in an in vivo setting, but also for uncovering novel functions for a gene that were not anticipated from conventional in vitro experiments. In the field of apoptosis, as for many other areas of biomedical research, knockout mice and cell lines can be used as models for studying human disease, with the ultimate goal of developing therapeutic strategies.

Preoperative sonographic diagnosis of midgut malrotation with volvulus in adults: the "whirlpool" sign

Midgut malrotation and volvulus, found mostly in children, are rare and difficult to diagnose preoperatively in adults. We report 2 cases in which a 68-year-old man and a 75-year-old woman presented with intermittent cramping abdominal pain, abdominal distention, and vomiting. Abdominal sonography demonstrated wrapping of the superior mesenteric vein and bowel loops around the superior mesenteric artery (the "whirlpool sign") in both patients. Abdominal CT revealed similar findings. The diagnoses of midgut volvulus and mesenteric malrotation were made, and the patients underwent laparotomy. The man was confirmed to have duodenojejunal malrotation and volvulus, and the woman had cecal volvulus. The whirlpool sign is valuable for the preoperative diagnosis of mesenteric vessel malrotation and midgut volvulus.

TRAF6 deficiency results in osteopetrosis and defective interleukin-1, CD40, and LPS signaling

Bone resorption and remodeling is an intricately controlled, physiological process that requires the function of osteoclasts. The processes governing both the differentiation and activation of osteoclasts involve signals induced by osteoprotegerin ligand (OPGL), a member of tumor necrosis factor (TNF) superfamily, and its cognate receptor RANK. The molecular mechanisms of the intracellular signal transduction remain to be elucidated. Here we report that mice deficient in TNF receptor-associated factor 6 (TRAF6) are osteopetrotic with defects in bone remodeling and tooth eruption due to impaired osteoclast function. Using in vitro assays, we demonstrate that TRAF6 is crucial not only in IL-1 and CD40 signaling but also, surprisingly, in LPS signaling. Furthermore, like TRAF2 and TRAF3, TRAF6 is essential for perinatal and postnatal survival. These findings establish unexpectedly diverse and critical roles for TRAF6 in perinatal and postnatal survival, bone metabolism, LPS, and cytokine signaling.

Requirement of FADD for tumor necrosis factor-induced activation of acid sphingomyelinase

The generation of mice strains deficient for select members of the signaling complex of the 55-kDa tumor necrosis factor receptor (TNF-R55) has allowed the assignment of specific cellular responses to distinct TNF-R55-associated proteins. In particular, the TNF-R55-associated protein FADD seems to be responsible for recruitment and subsequent activation of caspase 8. In this report we demonstrate the requirement of FADD for TNF-induced activation of endosomal acid sphingomyelinase (A-SMase). In primary embryonic fibroblasts from FADD-deficient mice the activation of A-SMase by TNF-R55 ligation was almost completely impaired. This effect is specific in that other TNF responses like activation of NF-kappaB or neutral (N-)SMase remained unaffected. In addition, interleukin-1-induced activation of A-SMase in FADD-deficient cells was unaltered. In FADD-/- embryonic fibroblasts reconstituted by transfection with a FADD cDNA expression construct, the TNF responsiveness of A-SMase was restored. The results of this study suggest that FADD, in addition to its role in triggering a proapoptotic caspase cascade, is required for TNF-induced activation of A-SMase.

E1A-induced processing of procaspase-8 can occur independently of FADD and is inhibited by Bcl-2

Expression of the 243-residue form of the adenovirus E1A protein in the absence of other viral proteins triggers apoptosis by a pathway that requires p53. This pathway includes processing and activation of initiator procaspase-8, redistribution of cytochrome c, and activation of procaspase-3. Bcl-2 functions at or upstream of procaspase-8 processing to inhibit all of these events and prevent cell death. This contrasts with the anti-apoptotic influence of Bcl-2 family proteins in the cell death pathway induced by Fas ligand or tumor necrosis factor (TNF), in which Bcl-2 typically acts downstream of Fas/TNFR1-mediated activation of caspase-8. Moreover, E1A induces procaspase-8 processing and cell death in cells deleted of FADD, an adaptor protein critical for Fas/TNFR1 activation of caspase-8. The results indicate that E1A is capable of activating caspase-8 by a Bcl-2-inhibitable pathway that does not involve autocrine stimulation of FADD-dependent death receptor pathways.

Activation of the dsRNA-dependent protein kinase, PKR, induces apoptosis through FADD-mediated death signaling

The dsRNA-dependent protein kinase (PKR) is considered to play a key role in interferon-mediated host defense against viral infection and conceivably malignant transformation. To investigate further the mechanisms of PKR-induced growth inhibition, we have developed tetracycline-inducible murine cell lines that express wild-type PKR or a catalytically inactive PKR variant, PKRdelta6. Following induction, the growth of the wild-type PKR-expressing cells was similar to that of cells transfected with vector alone, while cells expressing PKRdelta6 became malignantly transformed. Significantly, treatment with dsRNA caused the wild-type PKR-overexpressing cells to undergo programed cell death while, conversely, cells expressing PKRdelta6 were completely resistant. Our studies demonstrated that activation of PKR induces the expression of members of the tumor necrosis factor receptor (TNFR) family, including Fas (CD95/Apo-1) and pro-apopotic Bax. In contrast, transcripts representing Fas, TNFR-1, FADD (Fas-associated death domain), FLICE, Bad and Bax were ablated in cells expressing PKRdelta6. The involvement of the death receptors in PKR-induced apoptosis was underscored by demonstrating that murine fibroblasts lacking FADD were almost completely resistant to dsRNA-mediated cell death. Thus, PKR, a key cellular target for viral repression, is a receptor/inducer for the induction of pro-apoptotic genes by dsRNA and probably functions in interferon-mediated host defense to trigger cell death in response to virus infection and perhaps tumorigenesis.

CD28-independent, TRAF2-dependent costimulation of resting T cells by 4-1BB ligand

4-1BB ligand (4-1BBL) is a member of the tumor necrosis factor (TNF) family expressed on activated antigen-presenting cells. Its receptor, 4-1BB, is a member of the TNF receptor family expressed on activated CD4 and CD8 T cells. We have produced a soluble form of 4-1BBL using the baculovirus expression system. When coimmobilized on plastic with anti-CD3, soluble 4-1BBL induces interleukin (IL)-2 production by resting CD28+ or CD28- T cells, indicating that 4-1BBL can function independently of other cell surface molecules, including CD28, in costimulation of resting T cell activation. At low concentrations of anti-CD3, 4-1BBL is inferior to anti-CD28 in T cell activation. However, when 4-1BB ligand is provided together with strong TCR signals, then 4-1BBL and anti-CD28 are equally potent in stimulation of IL-2 production by resting T cells. We find that TNF receptor-associated factor (TRAF)1 or TRAF2 associate with a glutathione S-transferase-4-1BB cytoplasmic domain fusion protein in vitro. In T cells, we find that association of TRAF1 and TRAF2 with 4-1BB requires 4-1BB cross-linking. In support of a functional role for TRAF2 in 4-1BB signaling, we find that resting T cells isolated from TRAF2-deficient mice or from mice expressing a dominant negative form of TRAF2 fail to augment IL-2 production in response to soluble 4-1BBL. Thus 4-1BB, via the TRAF2 molecule, can provide CD28-independent costimulatory signals to resting T cells.

FADD: essential for embryo development and signaling from some, but not all, inducers of apoptosis

FADD (also known as Mort-1) is a signal transducer downstream of cell death receptor CD95 (also called Fas). CD95, tumor necrosis factor receptor type 1 (TNFR-1), and death receptor 3 (DR3) did not induce apoptosis in FADD-deficient embryonic fibroblasts, whereas DR4, oncogenes E1A and c-myc, and chemotherapeutic agent adriamycin did. Mice with a deletion in the FADD gene did not survive beyond day 11.5 of embryogenesis; these mice showed signs of cardiac failure and abdominal hemorrhage. Chimeric embryos showing a high contribution of FADD null mutant cells to the heart reproduce the phenotype of FADD-deficient mutants. Thus, not only death receptors, but also receptors that couple to developmental programs, may use FADD for signaling.

Early lethality, functional NF-kappaB activation, and increased sensitivity to TNF-induced cell death in TRAF2-deficient mice

TRAF2 is an intracellular signal-transducing protein recruited to the TNFR1 and TNFR2 receptors following TNF stimulation. To investigate the physiological role of TRAF2, we generated TRAF2-deficient mice. traf2-/- mice appeared normal at birth but became progressively runted and died prematurely. Atrophy of the thymus and spleen and depletion of B cell precursors also were observed. Thymocytes and other hematopoietic progenitors were highly sensitive to TNF-induced cell death and serum TNF levels were elevated in these TRAF2-deficient animals. Examination of traf2-/- cells revealed a severe reduction in TNF-mediated JNK/SAPK activation but a mild effect on NF-kappaB activation. These results suggest that TRAF2-independent pathways of NF-kappaB activation exist and that TRAF2 is required for an NF-kappaB-independent signal that protects against TNF-induced apoptosis.

Regulation of adipose maturation and energy homeostasis

The adipose tissue of mammals represents a dynamic organ disseminated throughout the body. It fluctuates in abundance according to the availability of metabolic energy supplies. Mature adipose tissue communicates with the central nervous system via a hormonal circuit that controls satiety. Adipogenesis can be recapitulated in cell culture, thus facilitating molecular biological studies of the regulatory proteins that control this process. Such studies have led to the identification of two families of transcription factors that regulate adipogenesis and mammalian energy homeostasis.

Rapamycin inhibits clonal expansion and adipogenic differentiation of 3T3-L1 cells

Differentiating 3T3-L1 cells express an immunophilin early during the adipocyte conversion program as described in this issue [Yeh, W.-C., Li, T.-K., Bierer, B. E. & McKnight, S. L. (1995) Proc. Natl. Acad. Sci. USA 92, 11081-11085]. The temporal expression profile of this protein, designated FK506-binding protein (FKBP) 51, is concordant with the clonal-expansion period undertaken by 3T3-L1 cells after exposure to adipogenic hormones. Having observed FKBP51 synthesis early during adipogenesis, we tested the effects of three immunosuppressive drugs--cyclosporin A, FK506, and rapamycin--on the terminal-differentiation process. Adipocyte conversion was not affected by either cyclosporin A or FK506 and yet was significantly reduced by rapamycin at drug concentrations as low as 10 nM. Clonal expansion was impeded in drug-treated cultures, as was the accumulation of cytoplasmic lipid droplets normally seen late during differentiation. Rapamycin treatment likewise inhibited the expression of CCAAT/enhancer binding protein alpha, a transcription factor required for 3T3-L1 cell differentiation. All three of these effects were reversed by high FK506 concentrations, indicating that the operative inhibitory event was mediated by an immunophilin-rapamycin complex.

Identification and characterization of an immunophilin expressed during the clonal expansion phase of adipocyte differentiation

Mouse 3T3-L1 cells differentiate into fat-laden adipocytes in response to a cocktail of adipogenic hormones. This conversion process occurs in two discrete steps. During an early clonal expansion phase, confluent 3T3-L1 cells proliferate and express the products of the beta and delta members of the CCAAT/enhancer binding protein (C/EBP) family of transcription factors. The cells subsequently arrest mitotic growth, induce the expression of the alpha form of C/EBP, and acquire the morphology of fully differentiated adipocytes. Many of the genes induced during the terminal phase of adipocyte conversion are directly activated by C/EBP alpha, and gratuitous expression of this transcription factor is capable of catalyzing adipose conversion in a number of different cultured cell lines. The genetic program undertaken during the clonal expansion phase of 3T3-L1 differentiation, controlled in part by C/EBP beta and C/EBP delta, is less clearly understood. To study the molecular events occurring during clonal expansion, we have identified mRNAs that selectively accumulate during this phase of adipocyte conversion. One such mRNA encodes an immunophilin hereby designated FKBP51. In this report we provide the initial molecular characterization of FKBP51.

Cascade regulation of terminal adipocyte differentiation by three members of the C/EBP family of leucine zipper proteins

Terminal differentiation of cultured 3T3-L1 fibroblasts to the adipogenic phenotype is potently stimulated by dexamethasone (DEX) and methylisobutylxanthine (MIX). Previous studies have shown that these hormones induce the expression of genes encoding two members of the CCAAT/enhancer binding protein (C/EBP) family of transcription factors. In the absence of new protein synthesis DEX activates the gene encoding C/EBP delta. Likewise, MIX is a direct inducer of C/EBP beta gene expression. Optimal conditions for differentiation entail a 2-day period wherein confluent fibroblasts are exposed to DEX and MIX, followed by removal of the hormones and subsequent culture in the presence of insulin and fetal bovine serum. During the early phase of differentiation, high levels of C/EBP delta and C/EBP beta accumulate. These transcription factors diminish during the terminal phase of differentiation and come to be replaced by a third member of the C/EBP family, C/EBP alpha. Conclusive evidence has already shown that C/EBP alpha regulates terminal adipocyte differentiation, turning on the battery of fat-specific genes required for the synthesis, uptake, and storage of long chain fatty acids. Here we provide evidence that C/EBP delta and C/EBP beta play early catalytic roles in the differentiation pathway, relaying the effects of the hormonal stimulants DEX and MIX in a cascade-like fashion, leading to the activation of the gene encoding C/EBP alpha. Conditions facilitating the precocious expression of either C/EBP delta or C/EBP beta were observed to accelerate adipogenesis and, in the case of C/EBP beta, relieve dependence on the early hormonal stimulants. Likewise, conditions that prevented the expression of functional C/EBP beta effectively blocked terminal differentiation. Finally, we have discovered that ectopic expression of C/EBP beta in multipotential NIH-3T3 cells results in their conversion into committed adipoblasts capable, upon hormonal stimulation, of synchronous and uniform differentiation into fat-laden adipocytes.