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PubMed2001

Nitric oxide synthase inhibitors decrease coronary sinus-free radical concentration and ameliorate myocardial stunning in an ischemia-reperfusion model.

OBJECTIVES: Our objective was to determine the effect of a nitric oxide synthase inhibitor, NG-nitro-L-arginine (L-NNA) on free radical generation and myocardial contractility after ischemia-reperfusion. BACKGROUND: Cardiotoxic free radicals are generated by ischemia-reperfusion sequences. Nitric oxide reacts with superoxide radical to form peroxynitrite, which generates additional free radicals. Our hypothesis was that by inhibiting NO production, free radical formation will be diminished, which should be cardioprotective. METHODS: We studied 32 dogs. Coronary occlusion-reperfusion (20 min each) sequences were created by intracoronary balloon angioplasty inflation-deflation. Using electron paramagnetic resonance, we monitored the coronary sinus concentration of ascorbate free radical (Asc*-), a measure of total oxidative flux. The L-NNA (4.8 mg/kg total) was infused intravenously during occlusion-reperfusion; control dogs received saline. Immunohistochemical staining demonstrated the peroxynitration product nitrotyrosine. RESULTS: In the control dogs Asc*- rose from 3.2 +/- SD 0.5 nmol/l to 4.8 +/- 1.1 nmol/l with reperfusion, a 50% rise. With L-NNA the Asc*- rose from 3.2 +/- 0.9 nmol/l to 4.0 +/- 1.2 nmol/l, a 25% rise (p < 0.01, L-NNA vs. control). Echocardiographic left ventricular fractional area shortening (FAS) in the control dogs declined from 38 +/- 19% (baseline) to 26 +/- 14% (ischemia), and to 22 +/- 11% with reperfusion (p < 0.01 vs. baseline). With L-NNA, FAS declined from 36 +/- 13% (baseline) to 27 +/- 12% (ischemia) but then rose to 33 +/- 14 with reperfusion (p = NS vs. baseline). Nitrotyrosine was present in the myocardium subjected to ischemia-reperfusion, but almost absent in dogs receiving L-NNA. Myocardial perfusion was not altered by L-NNA. CONCLUSIONS: The NO synthase inhibitors decrease coronary sinus free radical concentration and ameliorate myocardial stunning after ischemia-reperfusion.

Animals↗

PubMed2025

Investigation of a Mycobacterium fortuitum prosthetic joint infection outbreak at two ambulatory surgery centers in Tennessee.

OBJECTIVE: This study outlines the investigation into an outbreak of Mycobacterium fortuitum infections involving 17 cases undergoing hip or knee surgeries at two ambulatory surgery centers (ASCs) in Tennessee from January 2023 to November 2024. Notably, the outbreak could not be attributed to contaminated water sources, which are typically associated with non-tuberculous mycobacteria (NTM) outbreaks, presenting a unique challenge. METHODS: Outbreak investigation steps included Infection Prevention (IP) assessments, case-control study, environmental sampling, whole genome sequencing, and a healthcare personnel (HCP) exposure questionnaire. RESULTS: IP assessment highlighted several concerns, including no formal facility water management program (WMP), a lack of dedicated IP personnel and certified sterile processing staff, the absence of a formalized system for tracking surgical site infections, and a notable gap in understanding the requirements for reporting diseases. The case-control findings revealed a significant association between the presence of a surgical technologist in the operating room during the procedures and the occurrence of NTM infections, indicated by an odds ratio of 55.77 (95% CI [3.16-985.44]; P = 0.0097). Thirteen clinical isolates collected at one ASC and three additional isolates collected at a second ASC were highly related by whole genome sequencing. CONCLUSION: The study further elucidates valuable insights gained from the outbreak response, including the gaps in surveillance within the ambulatory surgical setting and systematic collection of cultures from environmental sources. It emphasizes the importance of thorough vetting, onboarding, continuing education, and practice monitoring for HCP.

Humans↗

PubMed1998

Detection of conformational changes in an immobilized protein using surface plasmon resonance.

Utilizing surface plasmon resonance (SPR), we have developed novel methodology for the detection of conformational change(s) in immobilized proteins. A genetically altered E. coli dihydrofolate reductase (DHFR-ASC) was attached to a carboxymethyldextran matrix layer covering the sensor surface of an SPR biosensor through a disulfide linkage at the engineered protein's C-terminus. The DHFR-ASC-immobilized surface exhibited a larger response to acid treatment than reference surfaces lacking immobilized proteins. The SPR signal of the tethered protein and the molar ellipticity of DHFR-ASC in solution responded similarly to pH changes, consistent with the interpretation that changes in the SPR signal reflect conformational changes occurring during acid denaturation. A pH shift observed between the SPR signal and ellipticity changes may reflect a difference between surface and bulk pH. The tethered protein sensor surface was stable to repeated acid treatment using solutions in the pH range of 0.12-7.80 and yielded reproducible measurements. This is the first demonstration of detection of conformational changes in an immobilized protein using an SPR biosensor. This technique has potential for developing novel sensors and/or switching devices in response to protein conformational changes.

Biosensing Techniques↗

PubMed2003

Immunomodulatory effects of tetrachlorobenzoquinone, a reactive metabolite of hexachlorobenzene.

Hexachlorobenzene (HCB) is an environmental pollutant that causes autoimmune-like effects in humans and rats. It is not completely clear whether T cells are involved and, if so, how they are stimulated after oral exposure to HCB. HCB as a rather inert chemical is not likely to bind covalently to macromolecules. The oxidative metabolite of HCB, tetrachlorobenzoquinone (TCBQ), which is in a redox equilibrium with tetrachlorohydroquinone (TCHQ), can bind to macromolecules, hence may form hapten-carrier complexes in vivo. We have assessed in the reporter antigen-popliteal lymph node assay whether HCB or TCHQ and TCBQ are able to induce a 2,4,6-trinitrophenyl (TNP) specific IgG1 response to the T cell-independent antigen TNP-Ficoll, which is indicative of neoantigen specific T cell help. To this end, these compounds and silica were injected into the footpad of Balb/c mice. Silica was included as an inert model compound, which causes autoimmune-like effects by activating macrophages. Seven days later, cell number and TNP specific antibody-secreting cells (ASC) in the popliteal lymph node (PLN) were determined. Furthermore, a secondary PLNA was performed to find out if TCHQ was capable of eliciting a memory response. Silica, TCHQ, and TCBQ, but not HCB, increased PLN cellularity and the number of IgM-producing ASC by ELISPOT. Both oxidative metabolites were able to induce the formation of germinal centers as assessed by immunohistochemistry and an IgG1 response to TNP-Ficoll. In the secondary PLNA, only mice primed with TCHQ and challenged with TCHQ together with TNP-Ficoll showed a significant increase in TNP specific IgG1 ASC. Present data show that TCHQ and TCBQ are capable of inducing neoantigen specific T cell help and that TCHQ can induce a compound specific memory response.

Adjuvants, Immunologic↗

PubMed1999

Asthma symptoms: influence of personality versus clinical status.

The hypothesis that symptom-reporting in asthmatics does not necessarily correspond with clinical status, but is related to negative affectivity was investigated. One hundred and sixteen asthmatic patients filled out the Asthma Symptom Checklist (ASC), the Negative Emotionality Scale (NEM), and the McMaster-Asthma Quality-of-Life Questionnaire (AQLQ). The patients were grouped as either hospitalized, outpatient previously hospitalized or outpatient not previously hospitalized for asthma. Lung function data and Asthma Severity Scores (ASS) were also collected. The hospitalized group was retested after 3 months. The hospitalized group had lower AQLQ scores, higher ASS scores and worse lung function than both outpatient groups. However, the hospitalized group and the outpatients previously hospitalized group had higher ASC scores and NEM scores than the outpatients not previously hospitalized group. After discharge, when the hospitalized group had become clinically stable, their ASC and NEM scores remained comparable to those of the outpatient previously hospitalized group. Symptom-reporting in asthmatics is not necessarily in accordance with clinical status, but may be directly or indirectly mediated by personality, such as negative affectivity.

Adult↗

PubMed2003

Homing of antibody secreting cells.

As activated B cells differentiate into plasma cells they complete a final series of migration steps that take them to locations where they can efficiently carry out their effector function, secreting immunoglobulin (Ig) M or IgG into circulation or releasing dimeric IgA adjacent to the epithelium for transcytosis. Recent experiments have established a key role for chemokines in directing antibody secreting cell (ASC) movement within the secondary lymphoid organs where they are generated, as well as in guiding the cells to the bone marrow or mucosal surfaces. This review discusses the chemokines involved in directing ASC movements, particularly focusing on the role of CXCR4 and CXCL12/SDF1. The function of CCR9 and CCR10 in IgA ASC homing and contributions made by integrins and lectins are also discussed.

Animals↗

PubMed1991

Glutamine transport by basolateral plasma-membrane vesicles prepared from rabbit intestine.

L-Glutamine, a major energy substrate for intestinal epithelial cells, can be extracted from intraluminal contents across the brush-border membrane and from arterial blood via the basolateral membrane. The purpose of the present study was to characterize glutamine transport by the basolateral membrane of rabbit epithelial cells. Transport of glutamine by isolated basolateral-membrane vesicles was mediated by both Na(+)-dependent and Na(+)-independent carriers. Tests were performed to distinguish glutamine uptake by likely transport agencies, including Systems A, ASC, N, IMINO, NBB, L and asc. The Na(+)-dependent glutamine uptake was strongly inhibited by an excess of 2-(methylamino)isobutyric acid (MeAIB), and glutamine was equally effective in inhibiting MeAIB transport. The reciprocal inhibition analysis, as well as a sensitivity to increased H+ concentration, indicates that Na(+)-dependent glutamine transport across the basolateral membrane is mediated by System A. The saturable Na(+)-independent glutamine transport was markedly inhibited by 2-aminobicyclo-[2,2,1]-heptane-2-carboxylic acid ('BCH') and insensitive to changes in assay pH, suggesting uptake via System L rather than System asc. The presence of a Na(+)-dependent carrier to mediate active transport of glutamine across the basolateral membrane is probably essential to ensure a continuous supply of this vital substrate to the enterocyte in the post-absorptive state.

Animals↗

PubMed1998

The immunosuppressive activity of Ascaris suum is due to high molecular weight components.

The role of isolated components obtained by gel filtration chromatography of Ascaris suum body extract (Asc) on the modulation of the immune response to ovalbumin (OvA) was evaluated and correlated with the immunogenic properties of such components. We showed that high (PI), but not low (PIII), molecular weight components have the ability to inhibit OvA-induced immediate and DTH reactions, lymph node (LN) cell proliferation, cytokine (IL-2, interferon-gamma (IFN-gamma), IL-4 and IL-10) and antibody (IgG1, IgG2a, IgM and IgE) production in mice concomitantly immunized with OvA and these high mol. wt components. The pattern of cytokines synthesized in response to PI or PIII was totally different: the former induced more IL-4 and IL-10 and the latter more IL-2 and IFN-gamma. The levels of Asc-specific IgG1 antibodies were higher in mice immunized with OvA plus PI and IgG2a anti-Asc antibodies predominated in those immunized with PIII. IgE antibody production, however, was low in the former group of mice. These results indicate that the high mol. wt components present in the body extract from the helminth A. suum are responsible for its suppressive effect upon Th1- and Th2-dependent immune responses to an unrelated antigen. The suppression of the Th1-dependent parameters could be related to high-level expression of IL-4 and IL-10 induced by such components.

Animals↗

PubMed2000

Frequent presence of neuroendocrine small cells in thymic carcinoma: a light microscopic and immunohistochemical study.

AIMS: Neuroendocrine differentiation has been described in conventional carcinomas of various organs. Small cells postulated to be neuroendocrine cells were observed previously in some thymic carcinomas. This study was conducted to confirm and characterize the presence of neuroendocrine small cells in thymic carcinomas by light microscopy and immunohistochemistry. METHODS AND RESULTS: Twenty-two thymic carcinomas were studied by light microscopy to detect the presence of small neuroendocrine-like cells. They were found in four of 10 squamous cell carcinomas (SCC) and seven of eight adenosquamous carcinomas (ASC). No small cells were observed in three lymphoepithelioma-like carcinomas (LELC) and one adenocarcinoma. The small cells were located within the tumour nests and constituted less than 1% of the entire tumour. In one case, small cells also extended outside the tumour nests. Rosette formation was seen in three cases. They were proved to be neuroendocrine cells by their immunoreactivity to neuron-specific enolase, chromogranin A, and/or synaptophysin. A few scattered neuroendocrine small cells were found only by immunohistochemistry in one case each of SCC, ASC, and LELC. The small cells were also strongly positive for cytokeratin (CK) 8 and CK18 but negative for CK19 and CK20. The predominant carcinoma cells other than the neuroendocrine small cells also displayed neuroendocrine markers in 68% of the cases studied. CONCLUSIONS: Neuroendocrine small cells can be recognized by light microscopic examination in approximately 61% of thymic SCC and ASC. Neuroendocrine markers, CK8 and CK18 can aid in confirming their presence. The neuroendocrine small cells present in thymic carcinomas are different from the main carcinoma cells displaying immunohistochemical neuroendocrine markers. The presence of neuroendocrine small cells could be an useful marker for the differentiation of thymic carcinomas from thymomas and carcinomas of other sites.

Adenocarcinoma↗

PubMed1997

Nasal lymphoid tissue (NALT) as a mucosal immune inductive site.

Intranasal (i.n.) immunization is a very effective route for inducing mucosal immunity, but the cellular mechanism responsible for regulating and disseminating these responses is not fully understood. The authors studied the role of nasal lymphoid tissue (NALT) as a mucosal inductive site by using highly purified NALT cells obtained by a new method of mechanical isolation. The NALT cells, like Peyer's patch (PP) cells, were smaller in size and less granular than lymphocytes from salivary glands (SG) and small intestinal lamina propria (LP). The NALT cells isolated from i.n. immunized mice contained antigen-specific antibody-secreting cells (ASC) predominantly of immunoglobulin (Ig)A isotype, similar to those also recovered from salivary glands in a time course study. However, the higher proportion of smaller sized sports formed by NALT cells in ELISPOT assays suggested that these cells were less differentiated precursors of those found in salivary glands. This was supported by the fact that after i.n. immunization, IgA ASC appeared in NALT, as well as in mucosal effector sites SG and LP, but none or very few in another mucosal inductive site, PP. In contrast, after intragastric (i.g.) immunization, IgA ASC were detected in PP, along with the SG and LP, but none or very few in NALT. Furthermore, after i.n. immunization, lymphocytes from NALT but not PP proliferated in response to the specific antigen in culture. These findings imply that NALT served as an inductive site for IgA antibody responses at mucosal effector sites.

Administration, Intranasal↗

PubMed1996

Glutamine transport in mouse cerebral astrocytes.

We measured initial influx and exchange of [14C]glutamine in primary astrocyte cultures in the presence and absence of Na+. Kinetic analysis of transport in Na+ -free solution indicated two saturable Na+ -independent components, one of which was identifiable functionally as system L1 transport. In the presence of Na+, multiple hyperbolic components were not resolvable from the kinetic data. Nevertheless, other evidence supported participation by at least three Na+ -dependent neutral amino acid transporters (systems A, ASC, and N). System A transport of glutamine was usually absent or minimal, based on lack of inhibition by alpha-(methylamino) isobutyric acid. However, vigorous system A-mediated transport emerged after derepression by substrate deprivation. Participation by system ASC was indicated by trans-acceleration of Na+ -dependent uptake, preferential inhibition of an Li+ -intolerant component of uptake by cysteine, and inhibition by cysteine of a component resistant to inhibition by histidine and alpha-(methylamino) isobutyric acid. Because nonsaturable transport of glutamine appeared negligible, and system L transport of glutamine was suppressed in the presence of Na+, low-affinity system ASC transport may be the major route of export of glutamine from astrocytes. At 700 microM glutamine, the primary uptake route was system N transport, identified on the basis of selective inhibition by histidine and asparagine, pH sensitivity, and tolerance of Li+ in place of Na+.

Amino Acids↗

PubMed2001

Use of capecitabine as first-line therapy in patients with metastatic breast cancer relapsing after high-dose chemotherapy and autologous stem cell support.

High-dose chemotherapy with autologous stem cell support (HDC-ASCS) can produce high complete remission rates in patients with metastatic breast cancer (MBC). However, the majority of those so treated will relapse within 3 years. The ability of such patients to tolerate further myelosuppressive chemotherapy may be limited and the best therapy is undefined. In this retrospective study we assessed the role of capecitabine as initial therapy after relapse. Ten patients (median age = 47 years; oestrogen receptor-positive, n = 4; visceral disease, n = 6; prior anthracycline, n = 8, prior taxanes, n = 10), whose disease progressed at a median of 246 days (range 69-480) after HDC-ASCS and who were treated with capecitabine (2500 mg/m2 per day for 2 weeks of a 3-week cycle) as initial therapy for relapse, were assessed retrospectively for response and toxicity. They received a median of eight cycles (range 4-24) of capecitabine. The toxicities encountered while receiving capecitabine were: hand-foot syndrome (grade 1, n = 3; grade 2, n = 4; grade 3, n = 1); diarrhoea (grade 1, n = 1; grade 2, n = 3); nausea (n = 2) and fatigue (n = 5). Haematological toxicity was seen in only one patient. No patient required hospitalization for toxicity. Three achieved a complete remission, four a partial remission and three disease stabilization. After a median follow-up of 183 days from commencing capecitabine (range 97-540), all patients were alive and five were in remission. Five progressed after remissions that lasted between 63 and 252 days. Oral capecitabine is an active and well-tolerated agent when used alone as first-line therapy in patients who have relapsed after HDC-ASCS for MBC.

Adult↗

PubMed2005

Static and dynamic thermal quantities near the consolute point of the binary liquid mixture aniline-cyclohexane studied with a photopyroelectric technique and adiabatic scanning calorimetry.

We studied the thermal conductivity, thermal effusivity, and specific heat capacity at constant pressure of the critical binary liquid mixture aniline-cyclohexane near the consolute point, using a photopyroelectric (PPE) technique and adiabatic scanning calorimetry (ASC). According to recent theoretical predictions based on renormalization group theory calculations, a substantial (but not diverging) enhancement in the thermal conductivity in the homogeneous phase near the critical temperature was expected for this binary system near the consolute point. However, within an experimental precision of 0.05%, we found no deviation from linear behavior in the range of 5 K above Tc down to Tc. The specific heat capacity calculated from the results for the thermal conductivity and effusivity is in good agreement with that measured by ASC. For the ASC results, the theoretical power law expression with the Ising critical exponent was fitted to the specific heat capacity both above and below the transition temperature. Good agreement with theory was found both for the amplitude ratio and the two-scale universality.

Journal Article↗

PubMed1993

Congenital absence of vas deferens treated by artificial spermatocele constructed from the tunica vaginalis; report of six cases.

Six patients with congenital absence of the vas deferens were treated by artificial spermatoceles (ASCs) in an attempt to collect sperm for subsequent artificial insemination (AI). The ASC was constructed from a flap of tunica vaginalis from the patient. Sperm were aspirated from the ASC each month; there was wide variation in the concentration of sperm recovered [33.0 +/- 48.2 x 10(6) mL-1 (range 0.1-200)] and motility and normal morphology of the sperm were 19.0 +/- 17.9% and 48.8 +/- 23.4% respectively. Although a total of 14 cycles of AI was performed using the aspirated sperm, pregnancy did not result. Both poor sperm recovery and poor motility contributed to this failure. The condition of the epididymis observed during scrotum examination is reported. It is suggested that in some patients with congenital absence of vas deferens, the paired Wolffian ducts may differ from each other in their development.

Adult↗

PubMed2006

The B30.2 domain of pyrin, the familial Mediterranean fever protein, interacts directly with caspase-1 to modulate IL-1beta production.

Familial Mediterranean fever (FMF) is a recessively inherited autoinflammatory disorder with high carrier frequencies in the Middle East. Pyrin, the protein mutated in FMF, regulates caspase-1 activation and consequently IL-1beta production through cognate interaction of its N-terminal PYRIN motif with the ASC adaptor protein. However, the preponderance of mutations reside in pyrin's C-terminal B30.2 domain. Here we demonstrate direct interaction of this domain with caspase-1. In lysates from cells not expressing ASC, reciprocal GST pull-downs demonstrated the interaction of pyrin with the p20 and p10 catalytic subunits of caspase-1. Coimmunoprecipitations of pyrin and caspase-1 from THP-1 human monocytic cells were consistent with the interaction of endogenous proteins. The C-terminal B30.2 domain of pyrin is necessary and sufficient for the interaction, and binding was reduced by FMF-associated B30.2 mutations. Full-length pyrin attenuated IL-1beta production in cells transfected with a caspase-1/IL-1beta construct, an effect diminished by FMF-associated B30.2 mutations and in B30.2 deletion mutants. Modeling of the crystal structure of caspase-1 with the deduced structure of the pyrin B30.2 domain corroborated both the interaction and the importance of M694V and M680I pyrin mutations. Consistent with a net inhibitory effect of pyrin on IL-1beta activation, small interfering RNA (siRNA)-mediated pyrin knockdown in THP-1 cells augmented IL-1beta production in response to bacterial LPS. Moreover, the IL-1 receptor antagonist anakinra suppressed acute-phase proteins in a patient with FMF and amyloidosis. Our data support a direct, ASC-independent effect of pyrin on IL-1beta activation and suggest heightened IL-1 responsiveness as one factor selecting for pyrin mutations.

Caspase 1↗

PubMed2002

Identification of a novel Na+-independent acidic amino acid transporter with structural similarity to the member of a heterodimeric amino acid transporter family associated with unknown heavy chains.

We identified a novel Na(+)-independent acidic amino acid transporter designated AGT1 (aspartate/glutamate transporter 1). AGT1 exhibits the highest sequence similarity (48% identity) to the Na(+)-independent small neutral amino acid transporter Asc (asc-type amino acid transporter)-2 a member of the heterodimeric amino acid transporter family presumed to be associated with unknown heavy chains (Chairoungdua, A., Kanai, Y., Matsuo, H., Inatomi, J., Kim, D. K., and Endou, H. (2001) J. Biol. Chem. 276, 49390-49399). The cysteine residue responsible for the disulfide bond formation between transporters (light chains) and heavy chain subunits of the heterodimeric amino acid transporter family is conserved for AGT1. Because AGT1 solely expressed or coexpressed with already known heavy chain 4F2hc (4F2 heavy chain) or rBAT (related to b(0,+)-amino acid transporter) did not induce functional activity, we generated fusion proteins in which AGT1 was connected with 4F2hc or rBAT. The fusion proteins were sorted to the plasma membrane and expressed the Na(+)-independent transport activity for acidic amino acids. Distinct from the Na(+)-independent cystine/glutamate transporter xCT structurally related to AGT1, AGT1 did not accept cystine, homocysteate, and l-alpha-aminoadipate and exhibited high affinity to aspartate as well as glutamate, suggesting that the negative charge recognition site in the side chain-binding site of AGT1 would be closer to the alpha-carbon binding site compared with that of xCT. The AGT1 message was predominantly expressed in kidney. In mouse kidney, AGT1 protein was present in the basolateral membrane of the proximal straight tubules and distal convoluted tubules. In the Western blot analysis, AGT1 was detected as a high molecular mass band in the nonreducing condition, whereas the band shifted to a 40-kDa band corresponding to the AGT1 monomer in the reducing condition, suggesting the association of AGT1 with other protein via a disulfide bond. The finding of AGT1 and Asc-2 has established a new subgroup of the heterodimeric amino acid transporter family whose members associate not with 4F2hc or rBAT but with other unknown heavy chains.

Amino Acid Sequence↗

PubMed2004

PAN1/NALP2/PYPAF2, an inducible inflammatory mediator that regulates NF-kappaB and caspase-1 activation in macrophages.

Genes encoding proteins with PYRIN/PAAD/DAPIN domains, a nucleotide binding fold (NACHT), and leucine rich repeats have recently been recognized as important mediators in autoimmune inflammatory disorders. Here we characterize the expression and function of a member of the PYRIN and NACHT domain (PAN) family, PAN1 (also known as NALP2 and PYPAF2). PAN1 protein expression is regulated by lipopolysaccharide (LPS) and interferons (IFNbeta and IFNgamma) in THP-1 macrophage cells. In gene transfection studies PAN1 manifests an inhibitory influence on NF-kappaB activation induced by various pro-inflammatory stimuli, including tumor necrosis factor TNFalpha and interleukin-1beta (IL-1beta). Gene transfer-mediated elevations in PAN1 protein also suppressed activation of IkappaB kinases induced by inflammatory cytokines. Conversely, reducing endogenous levels of PAN1 using small interfering RNA enhanced LPS-induced production of ICAM-1 (intercellular adhesion molecule 1), an NF-kappaB-dependent gene. We also show here that PAN1 binds via its PYRIN domain to ASC, an adapter protein involved in caspase-1 activation. This binding is disrupted by mutation of the alpha1 helix of ASC. In gene transfer experiments PAN1 enhances caspase-1 activation and IL-1beta secretion in collaboration with ASC. Conversely, reducing endogenous levels of PAN1 using small interfering RNA significantly reduced LPS-induced secretion of IL-1beta in monocytes. We propose that PAN1 functions as a modulator of the activation of NF-kappaB and pro-caspase-1 in macrophages.

Adaptor Proteins, Signal Transducing↗

PubMed2004

Analysis of an Arabidopsis thaliana protein family, structurally related to cytochromes b561 and potentially involved in catecholamine biochemistry in plants.

Cytochromes b561 (cyts b561) constitute a family of eukaryotic membrane proteins, catalysing ascorbate (Asc)-mediated trans-membrane electron transport, and hence likely involved in Asc regeneration. A class of proteins (DoH-CB) has been identified in plants and animals, containing the cyt b561 electron-transport domain (CB), combined with the catecholamine-binding regulatory domain of dopamine-beta-hydroxylase (DoH). A mammalian DoH-CB protein was previously reported to function as a cell-derived growth factor receptor (SDR2). We have performed an in silico analysis on DoH-CB proteins from Arabidopsis thaliana and demonstrate that structural features of both CB and DoH domains are well conserved. The combination of both domains may have evolved from a functional interaction between a cyt b561 and a DoH-containing protein, illustrating the so-called "Rosetta Stone" evolutionary principle, and this hypothesis is supported by sequence comparisons. DoH-CB proteins form a newly identified group of proteins, likely to play a key role in catecholamine action in plants. It is suggested that these proteins may function as trans-membrane electron shuttles, possibly regulated by catecholamines. The role and action of catecholamines in plants is poorly documented, but it is clear that they are involved in many aspects of growth and development. Whether the DoH-CB proteins functionally interact with Asc, as is the case for cyts b561, remains to be determined.

Amino Acid Sequence↗