Evidence for common sites of contact between the antisigma factor SpoIIAB and its partners SpoIIAA and the developmental transcription factor sigmaF in Bacillus subtilis

The activity of the developmental transcription factor sigmaF in Bacillus subtilis is governed by a switch involving the dual function protein SpoIIAB. SpoIIAB is an antisigma factor that forms complexes with sigmaF and with an alternative partner protein SpoIIAA. SpoIIAB is also a protein kinase that can inactivate SpoIIAA by phosphorylating it on a serine residue. We sought to identify amino acids in SpoIIAB that are involved in the formation of the SpoIIAB-SpoIIAA complex by screening for mutants that were defective in the activation of sigmaF. This genetic screen, in combination with biochemical analysis and the construction of loss-of-side-chain (alanine substitution) mutants, led to the identification of amino acid side-chains in the N-terminal region of SpoIIAB that could contact SpoIIAA. Unexpectedly, the same amino acid side-chains (R20 and N50) that appear to touch SpoIIAA are required for binding to, and may represent sites of contact with, sigmaF. We propose that the N-terminal region of SpoIIAB forms a binding surface that is responsible for the formation of both the SpoIIAB-SpoIIAA and the SpoIIAB-sigmaF complexes, and that in some cases the same amino acid side-chains contact both partner proteins. N50 is also the defining residue of a region of amino acid sequence homology known as the N-box that is shared by SpoIIAB and related serine protein kinases, as well as by members of a mechanistically dissimilar family of protein kinases that undergo autophosphorylation at a histidine residue. We discuss the implications of this finding for the mechanism of histidine autophosphorylation.

The kinase activity of the antisigma factor SpoIIAB is required for activation as well as inhibition of transcription factor sigmaF during sporulation in Bacillus subtilis

The activity of the developmental transcription factor sigmaF in the spore-forming bacterium Bacillus subtilis is controlled by SpoIIAB, which sequesters sigmaF in an inactive complex. sigmaF is released from the SpoIIAB-sigmaF complex by the action of SpoIIAA, which triggers the dissociation of the complex. SpoIIAB is also a protein kinase that phosphorylates SpoIIAA on serine residue 58 (S58). This phosphorylation inactivates SpoIIAA and thus indirectly prevents the activation of sigmaF. Here, we report the identification of a patch of amino acid residues located in the vicinity of the adenosine nucleotide binding pocket of SpoIIAB that is required for the phosphorylation of SpoIIAA. A lysine substitution (E104K) at one of these residues (Glu104) markedly impaired the capacity of SpoIIAB to phosphorylate SpoIIAA in vitro as well as during sporulation. Kinetic analysis and evidence from the construction of alanine substitution mutants indicates that the side-chains of these amino acids could be contact sites for the SpoIIAA substrate during the phosphorylation reaction. Importantly, E104K and other kinase mutants blocked the activation of sigmaF during sporulation. This is paradoxical, because a mutant of SpoIIAA (S58A) that cannot be phosphorylated is known to cause higher than normal levels of sigmaF activity during sporulation. In resolution of this paradox, we present biochemical evidence indicating that SpoIIAA directly attacks the SpoIIAB-sigmaF complex and that SpoIIAA is phosphorylated as a result of this reaction. Consistent with this idea, mutations impairing kinase function of SpoIIAB were found to be epistatic to a mutation causing the S58A substitution in SpoIIAA; that is, cells producing mutant forms of both proteins were blocked in the activation of sigmaF. We conclude that phosphorylation of SpoIIAA plays a dual role in the sigmaF pathway, and that the kinase function of SpoIIAB is required for the activation as well as the inhibition of sigmaF during sporulation.

Neutralizing TNF-alpha activity modulates T-cell phenotype and function in experimental autoimmune uveoretinitis

Inhibiting TNF-alpha activity prevents tissue destruction without inhibiting retinal T cell infiltration in experimental autoimmune uveoretinitis (EAU) in Lewis rats. To further determine the role of TNF-alpha in autoimmune uveitis we characterized T cells isolated from retinae after treatment with a TNF-alpha antagonist. TNF-alpha activity was neutralized in vivo with a p55 TNF-alpha receptor-Ig fusion protein (sTNFr-Ig), administered 8 and 10 days after induction of EAU with heterologous retinal antigens. Retinal T-cell phenotype expression was examined by flow cytometry with respect to OX22 status (CD45RBlow or CD45RBhigh), activation (OX40 and CD25 expression) and rate of T-cell apoptosis (Annexin V+PI- expression). Lymphocyte reactivity was assessed by proliferation responses and cytokine production to retinal antigens. Despite greater than 40% of CD4+ T cells being activated at the height of disease, the proportion of OX22low expression was reduced and T cells exhibited reduced IFN-gamma and elevated IL-4 production. Retinal T cells maintained antigen-specific proliferation and demonstrated a low apoptotic rate. Although in both animal groups, comparable numbers of T cells were isolated, neutralizing TNF activity suppressed Th1 effector mechanisms protecting against target organ damage.

Squamous cell carcinoma in a patient with chronic lymphocytic leukemia. An intraoperative diagnostic challenge for the Mohs surgeon

BACKGROUND

Chronic lymphocytic leukemia (CLL) is the most common form of chronic leukemia in the US. CLL patients have an increased risk of developing other malignant neoplasms, especially skin cancer. Lymphoma-associated squamous cell carcinomas (SCCs) tend to behave more aggressively and therefore are often treated with Mohs micrographic surgery (MMS).

OBJECTIVE

To elucidate the potential difficulty of distinguishing perineural infiltrates as leukemic infiltrates versus inflammatory infiltrates associated with SCC on frozen tissue sections during MMS.

METHODS

This is a case report illustrating a patient with CLL who develops a SCC on the posterior ear. MMS was employed to treat the patient. Special immunohistochemical stains were performed to help distinguish the type of perineural infiltrate present.

RESULTS

The perineural infiltrate was shown by immunohistochemistry to be leukemic in origin. Special stains for keratin revealed no residual SCC hidden in the infiltrate.

CONCLUSION

CLL is a malignancy that primarily effects the elderly population and markedly increases their risk of developing skin cancers, especially SCC. An intense infiltrate may be present surrounding the tumor. This case report demonstrates one of the potential challenges the Mohs surgeon may face in interpreting histologic frozen section. Immunohistochemistry may be helpful in providing a more definitive answer to this problem.

Combining tabular, rule-based, and procedural knowledge in computer-based guidelines for childhood immunization

IMM/Serve is a computer program which implements the clinical guidelines for childhood immunization. IMM/Serve accepts as input a child's immunization history. It then indicates which vaccinations are due and which vaccinations should be scheduled next. The clinical guidelines for immunization are quite complex and are modified quite frequently. As a result, it is important that IMM/Serve's knowledge be represented in a format that facilitates the maintenance of that knowledge as the field evolves over time. To achieve this goal, IMM/Serve uses four representations for different parts of its knowledge base: (1) Immunization forecasting parameters that specify the minimum ages and wait-intervals for each dose are stored in tabular form. (2) The clinical logic that determines which set of forecasting parameters applies for a particular patient in each vaccine series is represented using if-then rules. (3) The temporal logic that combines dates, ages, and intervals to calculate recommended dates, is expressed procedurally. (4) The screening logic that checks each previous dose for validity is performed using a decision table that combines minimum ages and wait intervals with a small amount of clinical logic. A knowledge maintenance tool, IMM/Def, has been developed to help maintain the rule-based logic. The paper describes the design of IMM/Serve and the rationale and role of the different forms of knowledge used.

Role of adenosine nucleotides in the regulation of a stress-response transcription factor in Bacillus subtilis

The RNA polymerase sigma factor sigma B is a stress-response regulatory protein in Bacillus subtilis. The activity of sigma B is controlled in part by RsbW, a protein that inhibits sigma B, and RsbV, a protein that counteracts this inhibition. We now demonstrate that purified RsbW is capable of forming alternative complexes with either sigma B or RsbV. Sigma B in the RsbW. sigma B complex was transcriptionally inactive. RsbV reversed this inhibition by sequestering RsbW in a RsbW-RsbV complex, thereby allowing sigma B to remain free and active. In contrast to interactions among the components of the homologous regulatory system for the sporulation transcription factor sigma F, the binding of RsbW to RsbV and sigma B did not require adenosine nucleotides. Experiments involving the exchange of proteins between the two regulatory systems demonstrated that RsbW and its homolog in the sigma F system, SpoIIAB, exhibit strong preference in binding to RsbV and sigma B, and SpoIIAA and sigma F, respectively, and that the difference in nucleotide-dependence of binding between these two systems is attributable to a difference between RsbW and SpoIIAB. In confirmation and extension of previous results, we show that RsbW is also a protein kinase that uses ATP to phosphorylate RsbV, thereby blocking the capacity of RsbV to bind to RsbW and activate transcription. A close correlation was observed between the concentration of ATP required for efficient RsbW-mediated phosphorylation of RsbV, inhibition of RsbW.RsbV comlex formation, and inhibition of sigma B-directed transcription. These results are consistent with the hypothesis that activation of sigma B under certain stress condition is due to a decrease in cellular ATP levels.

SpoIIAA governs the release of the cell-type specific transcription factor sigma F from its anti-sigma factor SpoIIAB

The Bacillus subtilis transcription factor sigma F is a cell-type specific regulatory protein whose activity is governed by SpoIIAB and SpoIIAA and the nucleotides ATP and ADP. SpoIIAB is an anti-sigma factor that binds to sigma F in a manner that is stimulated by ATP, thereby trapping sigma F in an inactive complex. Alternatively, SpoIIAB binds to SpoIIAA in a manner that is stimulated by ADP to form a SpoIIAB.SpoIIAA complex in which SpoIIAB is sequestered from sigma F. SpoIIAB is also a protein kinase that uses ATP to phosphorylate, and thereby inactivate, SpoIIAA. Thus, ATP inhibits sigma F activity both by promoting formation of the SpoIIAB.sigma F complex and by phosphorylation of SpoIIAA. In extension of previous results, we use affinity chromatography to show that SpoIIAB is capable of forming long-lived complexes with sigma F and SpoIIAA and that the formation of these complexes is dependent on ATP and ADP, respectively. Using a DNA template lacking adenosine residues on the non-transcribed strand, we demonstrate that ATP is required for SpoIIAB-mediated inhibition of sigma F-directed RNA synthesis and that this inhibition is prevented by SpoIIAA in a manner that is stimulated by ADP. We show that ADP acts by protecting SpoIIAA from phosphorylation by SpoIIAB and that a mutant protein bearing an amino acid substitution at the site of phosphorylation in SpoIIAA is capable of preventing the inhibition of sigma F in a manner that does not depend on ADP. A principal finding from the investigation is that SpoIIAA restores activity to sigma F that had previously been inhibited by SpoIIAB. This is demonstrated both by the capacity of SpoIIAA to reverse SpoIIAB-mediated inhibition of sigma F-directed RNA synthesis and by its capacity to interact with and disrupt the SpoIIAB. sigma F complex. The results are consistent with a model in which sigma F is controlled by the cellular concentration of unphosphorylated SpoIIAA.

Health practices among Russian and Ukrainian immigrants

Since 1990, due to political and legislative changes, immigration from the former Soviet Union to the United States has increased significantly. Population reports from 1988 indicate that there were approximately 406,000 Soviet immigrants in the United States at that time. This number is expected to increase due to the Immigration Reform Act of 1990, which raised the Soviet refugee ceiling to 50,000 per year. Currently, very little is known about the health status and health practices of this population, although some published data indicate that life expectancy and infant mortality rates compare poorly with those of the general population in the United States. Although the former Soviet republics experienced universal health care coverage, there was little emphasis on promoting a healthy lifestyle. Heavy cigarette use, high alcohol intake, poor dietary intake, little attention to physical fitness, and crowded living conditions have been described. Environmental pollution and poor occupational safety are common and have contributed to the health problems of the population. As the influx of immigrants continues, the consequences of these health conditions will impose a burden on health care services in this country. As with any immigrant group, an understanding of the potential health conditions and cultural values can facilitate appropriate medical care. This research was conducted to explore these issues. Interviews and a physical assessment were conducted with 30 adults from the former Soviet Union. The major health problems identified included various dental conditions requiring treatment, obesity, and the absence of basic health screening measures such as cholesterol testing, high blood pressure screening, Pap smears, and mammograms. The authors also identified a need for translators and for education regarding preventative self-care, such as breast self-examinations.

SpoIIE governs the phosphorylation state of a protein regulating transcription factor sigma F during sporulation in Bacillus subtilis

Cell-specific activation of the transcription factor sigma F during sporulation in Bacillus subtilis is controlled by a regulatory pathway involving the proteins SpoIIE, SpoIIAA, and SpoIIAB. SpoIIAB is an antagonist of sigma F, and SpoIIAA, which is capable of overcoming SpoIIAB-mediated inhibition of sigma F, is an antagonist of SpoIIAB. SpoIIAA is, in turn, negatively regulated by SpoIIAB, which phosphorylates SpoIIAA on serine 58. SpoIIAA is also positively regulated by SpoIIE, which dephosphorylates SpoIIAA-P, the phosphorylated form of SpoIIAA. Here, isoelectric focusing and Western blot analysis were used to examine the phosphorylation state of SpoIIAA in vivo. SpoIIAA was found to be largely in the phosphorylated state during sporulation in wild-type cells but a significant portion of the protein that was unphosphorylated could also be detected. Consistent with the idea that SpoIIE governs dephosphorylation of SpoIIAA-P, SpoIIAA was entirely in the phosphorylated state in spoIIE mutant cells. Conversely, overexpression of spoIIE led to an increase in the ratio of unphosphorylated SpoIIAA to SpoIIAA-P and caused inappropriate activation of sigma F in the predivisional sporangium. We also show that a mutant form of SpoIIAA (SpoIIAA-S58T) in which serine 58 was replaced with threonine was present exclusively as SpoIIAA-P, a finding that confirms previous biochemical evidence that the mutant protein is an effective substrate for the SpoIIAB kinase but that SpoIIAA-S58T-P cannot be dephosphorylated by SpoIIE. We conclude that SpoIIE plays a crucial role in controlling the phosphorylation state of SpoIIAA during sporulation and thus in governing the cell-specific activation of sigma F.

IMM/Serve: a rule-based program for childhood immunization

A rule-based program, IMM/Serve, is being developed to help guide childhood immunization for initial use, within Oregon. The program is designed primarily for automated use with an online immunization registry, but can also be used interactively by a single user. The paper describes IMM/Serve and discusses 1) the sources of complexity in immunization logic, 2) the potential advantages of a rule-based approach for representing that logic, and 3) the potential advantage of such a program evolving to become the standard of care. Related projects include 1) a computer-based tool to help verify the completeness of the logic, 2) a tool that allows a central part of the logic to be generated automatically, and 3) an approach that allows visualization of the logic graphically.

Activation of cell-specific transcription by a serine phosphatase at the site of asymmetric division

Cell fate is determined by cell-specific activation of transcription factor sigma F after asymmetric division during sporulation by Bacillus subtilis. The activity of sigma F is governed by SpoIIAA, SpoIIAB, and SpoIIE, a membrane protein localized at the polar septum. SpoIIAB binds to and inhibits sigma F, and SpoIIAA inhibits SpoIIAB, which prevents SpoIIAB from binding to sigma F. SpoIIAB is also a serine kinase that inactivates SpoIIAA. Here, it is demonstrated that SpoIIE dephosphorylates SpoIIAA-P and overcomes SpoIIAB-mediated inhibition of sigma F. The finding that SpoIIE is a serine phosphatase links asymmetric division to the pathway governing cell-specific gene transcription.

Aromatase activity and interleukin-6 production by normal and malignant breast tissues

The aromatase enzyme complex, which regulates the conversion of androstenedione to estrone, may have an important role in regulating estrogen synthesis in breast tissues. In this study the effect of tumor location on aromatase activity in adjacent tissue was examined and related to interleukin-6 (IL-6) production, which has been shown to stimulate aromatase activity in breast cancer cells. Samples of normal and malignant breast tissues were obtained from 11 women undergoing mastectomy. In 7 patients, aromatase activity was highest in the quadrant in which the tumor was located or on which the tumor impinged. Aromatase activity in tumor-bearing quadrants was significantly higher than that in adjacent and opposite quadrants. Aromatase activity and IL-6 production, expressed in terms of tissue weight, were significantly higher for tumor tissue compared with normal breast adipose tissue. A significant correlation was found between aromatase activity and IL-6 production for breast tumor tissue (rs = 0.56; P < 0.05), but not for adipose tissue from the breast quadrants. Aromatase activity and IL-6 production were also measured in tissue obtained from a normal woman undergoing reduction mammoplasty who had previously had breast augmentation by silicone injection, not contained within a capsule. In tissue from this patient there was evidence of chronic inflammation and a marked macrophage response. Aromatase activity in this tissue was considerably higher than that detected in mastectomy adipose tissue samples, and a significant correlation was found between aromatase activity and IL-6 production (rs = 0.77; P < 0.05). A preliminary study to examine the potential role of cells of the immune system in regulating breast tissue aromatase activity revealed that conditioned medium collected from macrophages and lymphocytes could markedly stimulate aromatase activity in tumor-derived fibroblasts. The results of this study confirmed that breast tumor location can influence aromatase activity in adjacent tissues and showed that aromatase activity is increased in tumor-bearing quadrants. The increased production of IL-6 by tumor tissue and its correlation with aromatase activity suggest that tumors may be the major source of IL-6, which is able to influence aromatase activity in adjacent tissues.

Synthetic oligonucleotide cocktails as probes for detection of human parvovirus B19

A cocktail of 10 oligonucleotides selected at intervals along the length of the genome of human parvovirus B19 was labelled enzymically with digoxigenin and chemically with either digoxigenin (DIG) or dinitrophenyl (DNP). Chemical labelling was easier and more practical for the production of large quantities of probe. Pools labelled with either digoxigenin or DNP could detect 10 fg of B19 DNA in a dot blot reaction using an alkaline phosphatase antibody conjugate and colorimetric detection. Formalin fixed tissue from 11 consecutive cases of fetal hydrops were examined by in situ hybridisation (ISH). Both probe cocktails detected human parvovirus B19 DNA in 3 cases, with positive cells in all tissues examined and with equal sensitivity. The DNP pool is significantly cheaper and simpler to produce and could provide an inexpensive reagent suitable for diagnostic detection of viral nucleic acid in histopathological material.

Establishment of cell type specific gene transcription during sporulation in Bacillus subtilis

Asymmetric cell division during the process of sporulation in the bacterium Bacillus subtilis generates dissimilar progeny that exhibit distinct programs of gene transcription. Recent work reveals a partner switching mechanism that governs the activity of the sporulation regulatory protein sigma F and that may be responsible for the establishment of cell type specific gene transcription.

An adenosine nucleotide switch controlling the activity of a cell type-specific transcription factor in B. subtilis

The sigma F factor establishes cell type-specific gene transcription during sporulation in B. subtilis. sigma F is negatively regulated by SpollAB, which forms complexes with sigma F or SpollAA. ATP and its nonhydrolyzable analogs stimulate the formation of the SpollAB.sigma F complex, whereas ADP stimulates the formation of the SpollAB.SpollAA complex. Which protein SpollAB associates with is determined by the concentrations of the two nucleotides, on which basis we propose a partner-switching model for the regulation of sigma F: [formula: see text] Consistent with this model, SpollAA reverses SpollAB-mediated inhibition of sigma F-directed transcription in a manner that depends on ADP. Cell-specific activation of sigma F could be due to an alteration in adenosine nucleotide levels in one cell of the sporangium.

Co-amplification of the gene for parathyroid hormone-related protein (PTHRP) and KRAS2 in a human lung cancer cell line

Parathyroid hormone-related protein (PTHRP) is expressed in a large number of tumors and is the mediator of parathyroid hormone-like effects seen in humoral hypercalcemia of malignancy. The gene coding for PTHRP has been localised to the short arm of chromosome 12. This is at the same region as the oncogene KRAS2, and amplification of KRAS2 has previously been found in human lung cancer. The BEN cell line which is known to express PTHRP was established from a patient who had squamous cell carcinoma of the lung with hypercalcemia. Cytogenetic analysis of the BEN cell line revealed a very complex karyotype with many marker chromosomes. Chromosomal in situ hybridization with biotinylated DNA probes visualized by a biotin-streptavidin-polyalkaline-phosphatase complex was used to analyse two dicentric marker chromosomes containing homogeneously staining regions (hsr) in BEN. The hsr were found to contain amplified PTHRP and KRAS2 at levels of 30-fold and 14-fold per cell, respectively. The higher level of amplification of the PTHRP gene would suggest that PTHRP is the target gene of amplification in the amplicon. This is the first report of gene amplification of PTHRP and in addition its co-amplification with KRAS2.

SpoIIAB is an anti-sigma factor that binds to and inhibits transcription by regulatory protein sigma F from Bacillus subtilis

The sigma F factor is a regulatory protein that is responsible for directing gene expression in the forespore compartment of developing cells of the spore-forming soil bacterium Bacillus subtilis. The sigma F factor is encoded by the promoter-distal member of sporulation operon spoIIA, which consists of cistrons called spoIIAA, spoIIAB, and spoIIAC. Genetic evidence indicates that the activity of sigma F is negatively regulated by the product (SpoIIAB) of the spoIIAB cistron. We now report that SpoIIAB is capable of binding to sigma F and inhibiting its capacity to direct transcription by core RNA polymerase from the promoter for a forespore-expressed gene. SpoIIAB is an anti-sigma factor that may be directly involved in the compartmentalization of sigma F-directed gene expression.

Sexual function in women. Do antihypertensive drugs have an impact?

Drug-induced sexual dysfunction is well known to occur with antihypertensive drugs in men. There are much less data on the effects of drugs on female sexual function. The physiology of the female sexual response has similarities to that of the male sexual response and there are therefore good reasons for suspecting that antihypertensive drugs are likely to adversely affect sexual function in women. Present evidence suggests that clonidine, methyldopa, guanethidine and reserpine are associated with adverse effects on sexual function. In healthy volunteers, labetalol appears to reduce vaginal lubrication, but there are no studies in patients receiving the drug therapeutically. Thiazide diuretics may be associated with the worsening of sexual problems, which interestingly appear to be ameliorated by weight reduction. Present evidence on the effects of vasodilators is limited but the evidence suggests that sexual function in women receiving calcium antagonists is not altered by changing to an angiotensin converting enzyme (ACE) inhibitor. Although present evidence suggests that effects on female sexual function may not be very great, it should be recognised that there are very few data in this area. Further work is clearly necessary.

Inhibition of estrone sulfatase activity by estrone-3-methylthiophosphonate: a potential therapeutic agent in breast cancer

Many breast tumors are hormone dependent, and there is evidence that hydrolysis of estrone sulfate (E1S) to estrone, by estrone sulfatase, is an important source of the estrogen which is found in tumors. In this study, we have developed a novel pathway for the synthesis of estrone-3-methylthiophosphonate (E1-3-MTP) and examined its ability to inhibit estrone sulfatase activity in MCF-7 breast cancer cells and human placental and breast tumor preparations. In MCF-7 breast cancer cells, E1-3-MTP, 100 nM and 10 microM, inhibited estrone sulfatase activity by 52 and > 98%, respectively. The apparent Km and Vmax for E1S were 4.8 microM and 148 pmol/min/mg for placental and 16.9 microM and 38 pmol/min/mg for breast tumor preparations. Kinetic studies revealed that E1-3-MTP inhibited estrone sulfatase in a competitive manner with the Ki values for placental and tumor preparations being 14.6 and 32.8 microM, respectively. A comparison of the metabolism of [3H]E1S and [3H]E1-3-MTP by human placenta or rat liver revealed that, whereas 50-60% of [3H]E1S was converted to [3H]estrone, < 3% of [3H]E1-3-MTP was hydrolyzed. The development of an efficient inhibitor of estrone sulfatase, which is resistant to metabolism, will allow the importance of the estrone sulfatase pathway of estrogen formation in breast tumors to be assessed and such an inhibitor may have considerable potential as a therapeutic agent.