alpha1-Acid glycoprotein production in rat dorsal air pouch in response to inflammatory stimuli, dexamethasone and honey bee venom

This study shows the rapid and differential production of the 40-43 kDa and the 70-90 kDa alpha1-acid glycoprotein (AGP) fucosylated glycoforms after treatment of the dorsal air pouch with bacterial lipopolysaccharide (LPS), HgCl(2) or Freund's complete adjuvant (FCA). The 40-43 kDa and the 70-90 kDa AGP production is peaked 1-3 h post-LPS treatment. We observed that the responses to LPS and FCA are similar in that both AGP isoforms are induced whereas they differ in that the FCA exhibits a 6 h lag period. The response to HgCl(2,) however, exhibits the specific biphasic induction only of the 40-43 kDa AGP. The serum 40-43 kDa AGP glycoform gradually increases in response to all of the above stimulants and peaks by 24 h post- treatment. The increase of the 70-90 kDa AGP levels in the air pouch occurs in association with the accumulation of polymorphonuclear (PMN) cells while dexamethasone (DEX) increases only the 40-43 kDa AGP production in the absence of PMN accumulation. Macrophage-monocyte lineage cells forming the air pouch lining tissue may potentially be the cells that secrete the 40-43 kDa AGP while polymorphonuclear cells that infiltrate the air pouch secrete the 70-90 kDa AGP. The 40-43 kDa and 70-90 kDa AGP production induced by LPS in the air pouch precedes that of interleukin-1 (IL-1) or interleukin-6 (IL-6) while the 40-43 kDa AGP glycoform potentially increases IL-6 production by air pouch PMN exudate cells. These significant differences suggest a local pro-inflammatory role of AGP. Honeybee venom suppressed arthritis development and exhibited differential local or systemic regulation of AGP in serum vs. air pouch exudate or synovial fluid. This study with the air pouch model of facsimile synovium tissue suggests that local alpha1-acid glycoprotein (AGP) production may contribute to pro-inflammatory and anti-inflammatory activities during the local acute phase response or during chronic inflammatory stress as in arthritis.

Doppler-guided haemorrhoidal artery ligation, rectoanal repair, sutured haemorrhoidopexy and minimal mucocutaneous excision for grades III-IV haemorrhoids: a multicenter prospective study of safety and efficacy

OBJECTIVE

The isolated use of Doppler-guided haemorrhoidal artery ligation (DGHAL) may fail for advanced haemorrhoids (HR; grades III and IV). Suture haemorrhoidopexy (SHP) and mucopexy by rectoanal repair (RAR) result in haemorrhoidal lifting and fixation. A prospective evaluation was performed to evaluate the results of DGHAL combined with adjunctive procedures.

METHOD

The study included 147 patients with HR (male patients: 102; grade III: 95, grade IV: 52) presenting with bleeding (73%) and prolapse (62%).

RESULTS

More ligations were required for grade IV than grade III HR (10.7 + 2.8 vs 8.6 + 2.2, P < 0.001). SHP (28 patients) and RAR (18 patients) at 1-4 positions were deemed necessary in 46 (31%) patients. Minimal (muco-)cutaneous excision (MMCE) was added in 23 patients. SHP/RAR was applied more frequently in grade IV HR (60%vs 16%, P < 0.001). In patients not having MMCE, SHP/RAR was added in 57% of grade IV cases (P < 0.001). Complications included residual prolapse (10; two second surgery), bleeding (15; two second DGHAL), thrombosis (four), fissure (three) and fistula (one). Analgesia was required not at all, up to 1-3 days, 4-7 days and >7 days by 30%, 31%, 16% and 14% of the patients, respectively. SHP/RAR was associated with greater discomfort (17%vs 6%, P < 0.001). No differences were found between SHP and RAR. At an average follow-up of 15 months, 96% of patients were asymptomatic and 95% were satisfied.

CONCLUSIONS

DGHAL with the selective application of SHP/RAR is a safe and effective technique for advanced grade HR.

Immunostimulatory activity of potential probiotic yeast strains in the dorsal air pouch system and the gut mucosa

AIMS

To determine the immunostimulatory activity of 15 presumptive probiotic yeast strains in the dorsal air pouch system in comparison with their activity in the gut mucosa.

METHODS AND RESULTS

Presumptive probiotic yeast strains previously isolated from human gastrointestinal tract and Feta cheese were further characterized genotypically and biochemically. The Saccharomyces cerevisiae 982, Saccharomyces boulardii KK1 and Kluyveromyces lactis 630 strains exhibited in the air pouch increased polymorphonuclear cell influx and phagocytic activity as well as cytokine production with similar potency as the probiotics Ultra levure S. boulardii and Lactobacillus acidophilus NCFB 1748. Oral administration of these strains in mice results in differential activation of small intestine immune responses concerning IgA and cytokine production as well as Toll-like receptor expression.

CONCLUSION

Besides the Saccharomyces strains 982 and KK1, the K. lactis 630 strain could also be considered as a candidate probiotic.

SIGNIFICANCE AND IMPACT OF THE STUDY

The air pouch model may be used as an alternative and rapid method for the discrimination and selection of potential probiotic yeast strains.

Effects of endotoxin on serum chemokines in man

AIM

Endotoxin is known to be a primary initiator of sepsis and septic shock. Migration of immunocompetent cells due to chemotactic attraction plays a central role in the initiation of the immune response. Two major groups of chemokines can be distinguished: C-x-C chemokines like Interleukin-8 attract mainly neutrophils, C-C chemokines (e.g. RANTES) attract monocytes and T-cells. The aim of this study was to get further insight into chemokine profiles after a single endotoxin bolus in man.

MATERIALS AND METHODS

We investigated the effect of systemically administered endotoxin (4ng/kg BW i.v.) in 8 healthy volunteers. Clinical data (heart rate, mean arterial pressure, temperature), serum levels of IL-8, and RANTES, as well as white blood cell count were obtained before and hourly for five hours after endotoxin administration.

RESULTS

Heart rate and MAP showed significant changes (p<0.05) after 2-3 hours. All volunteers presented with low-grade fever after 2 hours. WBC was elevated 43% and 63% after 4 and 5 hours, respectively. Both chemokines were significantly different from baseline two hours after endotoxin challenge: While IL-8 was significantly increased RANTES serum levels were diminished.

CONCLUSION

From our data we conclude that this endotoxin model was effective to mimic the clinical appearance of sepsis. Chemokines like IL-8 and RANTES are integrated in the early immune response to endotoxin challenge in man.

Oxidatively damaged proteins of heart mitochondrial electron transport complexes

Protein modifications, such as carbonylation, nitration and formation of lipid peroxidation adducts, e.g. 4-hydroxynonenal (HNE), are products of oxidative damage attributed to reactive oxygen species (ROS). The mitochondrial respiratory chain Complexes I and III have been shown to be a major source of ROS in vitro. Additionally, modifications of the respiratory chain Complexes (I-V) by nitration, carbonylation and HNE adduct decrease their enzymatic activity in vitro. However, modification of these respiratory chain complex proteins due to in vivo basal level ROS generation has not been investigated. In this study, we show a basal level of oxidative damage to specific proteins of adult bovine heart submitochondrial particle (SMP) complexes, and find that most of these proteins are localized in the mitochondrial matrix. We postulate that electron leakage from respiratory chain complexes and subsequent ROS formation may cause damage to specific complex subunits and contribute to long-term accumulation of mitochondrial dysfunction.

Study of "de novo" malignancies among greek renal transplant recipients

The incidence of malignancy was estimated in 1055 renal transplant recipients, engrafted between 1983 and 2001 including 611 grafts from living and 444 from cadaveric donors. The meoplasms were 22 skin cancers, 18 Kaposi's sarcomas, 10 lymphomas nine non-Hodgkin's and one Hodgkin's lymphoma) and 24 visceral carcinomas. Skin cancers were completely excised. Patients with Kaposi sarcoma were treated by tapering the immunosuppression with cessation of cyclosporine. In addition, four patients received chemotherapy, and one of them received local radiotherapy. All patients with lymphomas were treated by cessation of calcineurin inhibitors with modulation of the immunosuppression to levels that were safe for the graft. Furthermore, five patients underwent first line chemotherapy, two patients radiotherapy and two patients, surgical removal of the tumor. The patients with visceral tumors were treated surgically with excision of the lesions when possible, without severe modification of the immunosuppressive regimen. Chemotherapy or radiotherapy was added accordingly. Disease-related mortality rate in patients with skin cancer was 4.5%; in Kaposi's Sarcoma cases 11.11%; in lymphomas 50%; and in all the other instances, 45.8%. This study shows the increased incidence of certain malignancies in transplant recipients, illustrating the importance of cancer surveillance following kidney transplantation. A substantial reduction or even cessation of immunosuppressive therapy may be necessary to achieve patient survival.

Age-associated differences in cardiovascular inflammatory gene induction during endotoxic stress

Upon physiological stress, families of stress response genes are activated as natural defense mechanisms. Here, we show that induction of specific inflammatory genes is significantly dysregulated and altered in the heart of aged (24--26-month-old) versus young (4-month-old) mice experimentally challenged with a bacterial endotoxin, lipopolysaccharide (LPS, 1.5 mg/kg of body mass). Whereas the LPS-mediated induction of cardiac mRNA for tumor necrosis factor alpha or inducible nitric-oxide synthase showed no age-associated differences, the induction of interleukin-1 beta (IL-1 beta) and intracellular adhesion molecule-1 was modestly extended with aging, and the induction of IL-6 was significantly prolonged with aging. This age-associated phenomenon occurred gradually from 4 to 17 months of age and became more evident after 23 months of age. The age-associated augmentation of the cardiac IL-6 induction was also dramatic at the protein level. Immunohistochemically, the LPS-induced cardiac IL-6 was localized mainly in the microvascular walls. Aged but not young mice showed a high mortality rate during these experiments. These results demonstrate that endotoxin-mediated induction of specific inflammatory genes in cardiovascular tissues is altered with aging, which may be causally related to the increased susceptibility of aged animals to endotoxic stress.

Regulation of CCAAT/enhancer-binding protein-beta isoform synthesis by alternative translational initiation at multiple AUG start sites

The mRNA of the intronless, single-copy CCAAT/enhancer-binding protein-beta (C/EBPbeta) gene encodes several isoforms that have truncated transcription activation domains. This occurs by the alternative translational initiation (ATI) at multiple AUG start sites. The C/EBPbeta mRNA has four in-frame AUGs and an internal out-of-frame AUG associated with a small open reading frame (sORF). Initiation of translation at the in-frame AUGs forms 40-kDa (AUG-1), 35-kDa (AUG-2), 20-kDa (AUG-3) and 8.5-kDa (AUG-4) isoforms. We show that in COS-1 cells the 20-kDa isoform is not a product of proteolysis of the higher molecular weight isoforms. The sORF contains an AUG and termination signal that may produce the oligopeptide MPPAAARRL. Our studies suggest that ATI involves three mRNA structural features: (i) the cap structure, (ii) the context of the Kozak sequences that flank the AUG and (iii) the integrity of the sORF. We propose that formation of C/EBPbeta isoforms is accomplished by a leaky ribosomal scanning mechanism that facilitates ATI of multiple internal AUGs.

Aging, oxidative responses, and proliferative capacity in cultured mouse aortic smooth muscle cells

The cellular mechanisms that contribute to the acceleration of atherosclerosis in aging populations are poorly understood, although it is hypothesized that changes in the proliferative capacity of vascular smooth muscle cells is contributory. We addressed the relationship among aging, generation of reactive oxygen species (ROS), and proliferation in primary culture smooth muscle cells (SMC) derived from the aortas of young (4 mo old) and aged (16 mo old) mice to understand the phenotypic modulation of these cells as aging occurs. SMC from aged mice had decreased proliferative capacity in response to α-thrombin stimulation, yet generated higher levels of ROS and had constitutively increased mitogen-activated protein kinase activity, in comparison with cells from younger mice. These effects may be explained by dysregulation of cell cycle-associated proteins such as cyclin D1 and p27Kip1 in SMC from aged mice. Increased ROS generation was associated with decreased endogenous antioxidant activity, increased lipid peroxidation, and mitochondrial DNA damage. Accrual of oxidant-induced damage and decreased proliferative capacity in SMC may explain, in part, the age-associated transition to plaque instability in humans with atherosclerosis.

Lifespan extension and delayed immune and collagen aging in mutant mice with defects in growth hormone production

Single-gene mutations that extend lifespan provide valuable tools for the exploration of the molecular basis for age-related changes in cell and tissue function and for the pathophysiology of age-dependent diseases. We show here that mice homozygous for loss-of-function mutations at the Pit1 (Snell dwarf) locus show a >40% increase in mean and maximal longevity on the relatively long-lived (C3H/HeJ x DW/J)F(1) background. Mutant dw(J)/dw animals show delays in age-dependent collagen cross-linking and in six age-sensitive indices of immune system status. These findings thus demonstrate that a single gene can control maximum lifespan and the timing of both cellular and extracellular senescence in a mammal. Pituitary transplantation into dwarf mice does not reverse the lifespan effect, suggesting that the effect is not due to lowered prolactin levels. In contrast, homozygosity for the Ghrhr(lit) mutation, which like the Pit1(dw) mutation lowers plasma growth hormone levels, does lead to a significant increase in longevity. Male Snell dwarf mice, unlike calorically restricted mice, become obese and exhibit proportionately high leptin levels in old age, showing that their exceptional longevity is not simply due to alterations in adiposity per se. Further studies of the Pit1(dw) mutant, and the closely related, long-lived Prop-1(df) (Ames dwarf) mutant, should provide new insights into the hormonal regulation of senescence, longevity, and late life disease.

Effects of mercuric chloride on the regulation of expression of the acute phase response components alpha(1)-acid glycoprotein and C/EBP transcription factors

We have previously shown that in response to treatment with HgCl(2), the adult mouse liver exhibits both transcriptional and translational regulation of the acute phase response genes. In this study we asked whether the heavy metal treatment affects the regulation of the C/EBP transcription factors which play a key role in regulation of the acute phase response gene. Our studies have shown that the AGP gene is transcriptionally activated while transcription of the CCAAT/enhancer-binding trans-activating protein (C/EBP)alpha gene is slightly down-regulated and that of the C/EBPbeta gene does not respond. Both the C/EBPalpha and C/EBPbeta mRNAs produce multiple isoforms possibly by alternative translation initiation (ATI) of multiple internal AUG initiation sites. The C/EBPbeta mRNA appears to be stabilized. Although similar regulatory processes occur in response HgCl(2) vs. LPS, our data suggest that the translational processes (ATI) are differentially affected. In addition, a major difference lies in the fact that the C/EBPbeta gene is not transcriptionally activated by HgCl(2). Our data show decreased binding activity and pool levels of the C/EBPalpha isoform (p42(C/EBPalpha)) and increased binding activity and pool levels of C/EBPbeta isoform (p35(C/EBPbeta)) in response to HgCl(2). We propose that this isoform may be involved in the regulation of AGP gene expression in response to heavy metals and that there is a significant difference between the HgCl(2)-mediated and LPS-mediated inflammatory response.

Expression and self-regulatory function of cardiac interleukin-6 during endotoxemia

Interleukin (IL)-6 reportedly has negative inotropic and hypertrophic effects on the heart. Here, we describe endotoxin-induced IL-6 in the heart that has not previously been well characterized. An intraperitoneal injection of a bacterial lipopolysaccharide into C57BL/6 mice induced IL-6 mRNA in the heart more strongly than in any other tissue examined. Induction of mRNA for two proinflammatory cytokines, IL-1beta and tumor necrosis factor (TNF)-alpha, occurred rapidly before the induction of IL-6 mRNA and protein. Although stimulation of isolated rat neonatal myocardial cells with IL-1beta or TNF-alpha induced IL-6 mRNA in vitro, nonmyocardial heart cells produced higher levels of IL-6 mRNA upon stimulation with IL-1beta. In situ hybridization and immunohistochemical analyses localized the IL-6 expression primarily in nonmyocardial cells in vivo. Endotoxin-induced expression of cardiac IL-1beta, TNF-alpha, and intercellular adhesion molecule 1 was augmented in IL-6-deficient mice compared with control mice. Thus cardiac IL-6, expressed mainly by nonmyocardial cells via IL-1beta action during endotoxemia, is likely to suppress expression of proinflammatory mediators and to regulate itself via a negative feedback mechanism.

Renal CCAAT/enhancer-binding proteins in experimental diabetes mellitus

There is evidence that mediators of inflammation including components of the cytokine system are present in human and experimental diabetic kidney disease. CCAAT/enhancer-binding proteins (C/EBPs) represent a family of cytokine-inducible transcription factors. C/EBPs themselves regulate cytokine expression and also the expression of acute-phase reactants and connective tissue proteins. At least three C/EBP isoforms (alpha, beta, delta) are known. Upon stimulation with cytokines or bacterial lipopolysaccharide, the expression of the alpha isoform typically decreases, and the expression of the beta and/or delta isoforms increases. In view of the fact that components of the inflammatory response are present in diabetic kidney disease, there is a potential that the expression and activity of renal C/EBPs are altered in the diabetic state. In this study we sought to examine the status of C/EBP proteins in kidneys of rats with streptozotocin-induced diabetes mellitus. Diabetes was induced in 5 male Sprague-Dawley rats. Eight weight-matched non-diabetic rats were used as controls. Animals were sacrificed after 4 weeks, and the whole kidney nuclear protein was extracted. An electrophoretic mobility shift assay showed that DNA-binding activity was present in all five kidney nuclear extracts of the diabetic animals, but in only 2 out of 8 control samples (p < 0.05). A supershift assay showed that the DNA-bound protein complex consisted mainly of the C/EBPbeta isoform. Western analysis showed an increase of the C/EBPbeta protein in renal nuclear extracts of the diabetic animals compared to controls (p < 0.05). There was a decrease of the C/EBPalpha protein in the kidney nuclear extracts of the diabetic animals compared to controls (p < 0.05). We conclude that renal C/EBP dynamics are altered in experimental diabetes mellitus and that the patterns of C/EBP changes resemble those observed after cytokine or lipopolysaccharide stimulation.

Induction of the alpha(1)-antichymotrypsin gene in the brain associated with TGF-beta1 deficiency or systemic administration of endotoxin

We report that mRNA levels for alpha(1)-antichymotrypsin (ACT), a component of beta-amyloid plaques in Alzheimer's disease, are significantly increased in the brains of two different mouse models that develop inflammation: (1) acute inflammation caused by intraperitoneal injection with lipopolysaccharide (LPS) and (2) chronic inflammation in knockout mice lacking the anti-inflammatory cytokine transforming growth factor beta1 (TGF-beta1). While brain mRNA levels for the inflammatory cytokines TNFalpha, IL-1beta, and IL-6 were all elevated in the LPS-injected mice, only the mRNA for IL-1beta increased significantly in TGF-beta1-deficient mice. The transcription factor C/EBPbeta was strongly activated in the brains of both models. These results support the hypothesis that, through induction of the ACT gene in the brain, inflammation plays an important role during the development of Alzheimer's disease and that IL-1beta and C/EBPbeta may be involved in this process.

Interference mapping of nuclear protein binding to the acute phase response element of the mouse alpha1 acid glycoprotein gene

Exchange in binding of transcription factors C/EBPalpha and C/EBPbeta at a regulatory site in the alpha1-acid glycoprotein (AGP) promoter, termed the acute phase response element (APRE), has been correlated with bacterial lipopolysaccharide (LPS) mediated induction. The APRE contains overlapping recognition sequences for C/EBP's and glucocorticoid receptor (GR). Electrophortetic mobility shift assays show that this site can bind both GR and C/EBP. However, using liver nuclear extract, which contains GR binding activity, only C/EBP binds to the APRE. Binding interference methods, using dimethyl sulfate and potassium permanganate modification of specific bases, detected interference only with modification of bases that are in the region of the C/EBP binding site that do not overlap with the GRE sequence. There are no significant differences between the interference patterns of control and LPS treated liver nuclear extracts, suggesting that the region of close contact between protein and DNA is similar for C/EBPalpha (untreated) and C/EBPbeta (treated).

Expression of the neutrophil chemokine KC in the colon of mice with enterocolitis and by intestinal epithelial cell lines: effects of flora and proinflammatory cytokines

IL-10 plays an important role in preventing excessive inflammation to the normal flora in the intestinal lumen. The purpose of this study was to compare the effect of normal flora on inflammation in mice in which the IL-10 gene was disrupted. IL-10 knock-out mice housed in germfree conditions remained healthy while those housed in conventional conditions developed colitis after weaning, suggesting that IL-10 inhibits the adverse responses to luminal Ag. Crypt abscesses were present in virtually all of the diseased animals as evidenced by flattening of the epithelial cells and a large number of neutrophils in the lumen of the crypt. Since KC is a chemokine that is capable of recruiting neutrophils in mice, mRNA and protein for KC was measured. Increased levels of both KC mRNA and protein were detected in the colon of diseased mice. To determine whether the epithelial cells were capable of synthesizing KC and contributing to neutrophil accumulation in the crypts, a murine intestinal epithelial cell line (Mode-K) was shown to express mRNA and protein for KC. Two cytokines induced in association with colitis in these mice, TNF-alpha and IFN-gamma, increased the expression of KC mRNA and protein in murine epithelial cells. However, IL-10 was incapable of decreasing the induction of KC, even though the cells expressed the IL-10 receptor. These results suggest that the neutrophil chemokine KC is produced by gastrointestinal epithelial cells in response to inflammatory mediators that are expressed following exposure to normal flora in animals lacking IL-10.

Regulation of LPS-mediated induction of C/EBP delta gene expression in livers of young and aged mice

The C/EBP family of transcription factors plays a major role in the regulation of families of stress response genes, in particular, the acute phase response genes. We have examined expression of the C/EBP delta gene during the bacterial lipopolysaccharide mediated induction of the acute phase response in livers of young (4 months) and aged (24-28 months) male C57B1/6 mice by Northern, Western, and Southwestern analyses. C/EBP delta mRNA is present at a low constitutive level, is induced by lipopolysaccharide, and reaches the same induced level in young and aged mice. Aged mice, however, show a higher constitutive, uninduced mRNA pool level and a delay in recovery to uninduced levels after lipopolysaccharide treatment. C/EBP delta mRNA is observable 30 min after lipopolysaccharide in total RNA, cytoplasmic and polysomal fractions. Specific full length 28-kDa nascent peptides are detectable in polysomes 90 min after lipopolysaccharide. mRNA and nascent peptides cosediment with large polysomes and C/EBP delta mRNA is shifted to larger polysomes in lipopolysaccharide treated aged mice, consistent with an increased rate of initiation. Specific DNA-binding activity of C/EBP delta protein in nuclear extracts was examined by electromobility shift and antibody supershift assay. The levels of C/EBP delta binding-activity, are consistent with the changes in mRNA levels in young lipopolysaccharide treated livers. These studies support our hypothesis that aged mice exhibit a state of chronic inflammation or stress in the absence of a stressor.

Effects of age on the posttranscriptional regulation of CCAAT/enhancer binding protein alpha and CCAAT/enhancer binding protein beta isoform synthesis in control and LPS-treated livers

The CCAAT/enhancer binding protein alpha (C/EBPalpha) and CCAAT/enhancer binding protein beta (C/EBPbeta) mRNAs are templates for the differential translation of several isoforms. Immunoblotting detects C/EBPalphas with molecular masses of 42, 38, 30, and 20 kDa and C/EBPbetas of 35, 20, and approximately 8.5 kDa. The DNA-binding activities and pool levels of p42(C/EBPalpha) and p30(C/EBPalpha) in control nuclear extracts decrease significantly whereas the binding activity and protein levels of the 20-kDa isoforms increase dramatically with LPS treatment. Our studies suggest that the LPS response involves alternative translational initiation at specific in-frame AUGs, producing specific C/EBPalpha and C/EBPbeta isoform patterns. We propose that alternative translational initiation occurs by a leaky ribosomal scanning mechanism. We find that nuclear extracts from normal aged mouse livers have decreased p42(C/EBPalpha) levels and binding activity, whereas those of p20(C/EBPalpha) and p20(C/EBPbeta) are increased. However, translation of 42-kDa C/EBPalpha is not down-regulated on polysomes, suggesting that aging may affect its nuclear translocation. Furthermore, recovery of the C/EBPalpha- and C/EBPbeta-binding activities and pool levels from an LPS challenge is delayed significantly in aged mouse livers. Thus, aged livers have altered steady-state levels of C/EBPalpha and C/EBPbeta isoforms. This result suggests that normal aging liver exhibits characteristics of chronic stress and a severe inability to recover from an inflammatory challenge.

Induction of a subgroup of acute phase protein genes in mouse liver by hyperthermia

We have demonstrated that two members of the acute phase reactant family of positively regulated genes, alpha 1-acid glycoprotein (AGP-1 and AGP-2) and C-reactive protein (CRP) are induced by hyperthermia, while two others, the serum amyloid A (SAA) and alpha 1-antitrypsin (AT) genes, are not. Albumin (ALB), a negative acute phase reactant gene, is also induced by hyperthermia. The AGP-1, AGP-2, and CRP genes require glucocorticoids, but not IL-6, IL-1 beta or TNF alpha in response to hyperthermia. As with LPS, the C/EBP beta mRNA levels increased, while the C/EBP alpha mRNA levels decreased in response to LPS. In contrast to the LPS response, C/EBP delta was unchanged. Protein pool levels and DNA-binding activities of the 35 and 20 kDa C/EBP beta isoforms increase, whereas protein pool levels of the 42 kDa C/EBP alpha decrease and the 30kDa remained high. These studies suggest that the synthesis of specific C/EBP alpha and C/EBP beta isoforms is induced by hyperthermia, and that the regulation of the AGP-1 and AGP-2 genes during heat stress may involve one of these isoforms. The difference between the responses to hyperthermia and LPS is that the former, may not involve the participation of cytokines. Furthermore, since cis-acting heat shock elements (HSE) are located in the promoter regions of the ALB, CRP, and C/EBP beta genes, these regulatory sequences may be involved in the in vivo activation of these genes by hyperthermia.

Age-associated alterations in hippocampal and basal forebrain nuclear factor kappa B activity

Age-related cognitive deficits are often associated with loss of cholinergic activity within the neurotrophin-dependent cholinergic neurons that project from the basal forebrain to the hippocampus. The cause of reduced cholinergic function is unknown, but alterations in transcription factor-signaling pathways causing altered gene expression may cause decreased specific tissue function, resulting in loss of cholinergic activity. We measured transcription factor Nuclear Factor kappa B by electrophoretic mobility shift assay and Western analysis in young and aged rat brain tissues and report that basal levels of Nuclear Factor kappa B DNA-binding activity increase in the hippocampus and basal forebrain with age to significantly higher levels at 30 months of age. This age-associated increase in binding activity is associated with increased translocation of p65 to the nucleus. These data show an age-associated alteration in Nuclear Factor kappa B signal transduction pathways that may contribute to age-associated decreases in specific tissue function.

Regulation of a novel gene encoding a lysyl oxidase-related protein in cellular adhesion and senescence

We report here a novel cDNA clone with a predicted protein sequence similar to lysyl oxidase. This full-length cDNA clone of 3432 base pairs (WS9-14) was isolated from human fibroblasts on the basis of its overexpression in senescent cells. It encodes an 87-kDa polypeptide, whose protein is a member of the scavenger receptor cysteine-rich family, because it contains four scavenger receptor cysteine-rich domains that are found in several secreted or cell surface proteins. The WS9-14 protein has a 48% identity with both lysyl oxidase and lysyl oxidase-like protein at a region corresponding to exons 2-6, implying the existence of a lysyl oxidase gene family. The pattern of WS9-14 gene expression by fibroblasts parallels pro-collagen I-alpha1 expression. Its mRNA level is induced by transforming growth factor beta-1 and indomethacin and inhibited by phorbol ester and retinoic acid. WS9-14 is abundantly expressed in all tumor cell lines examined that attach to culture dishes but not in cell lines that grow in suspension and is also up-regulated in senescent fibroblasts. These results suggest that WS9-14 gene encodes an extracellular protein that may be specifically involved in cell adhesion and senescence.

Early gene response to hepatic ischemia reperfusion

The purpose of this study was to define the differences in heat shock protein (hsp)70, albumin, alpha(-1)-acid glycoprotein (AGP), and CCAAT enhancer binding proteins (C/EBP) alpha and beta mRNA between hepatic ischemia and reperfusion, and to begin to explore C/EBP protein production. These genes have been found important in the hepatic response to lipopolysaccharide and inflammation. In two experiments, Sprague-Dawley rats underwent temporary occlusion of the median and left hepatic lobe vasculature. The first experiment included a single sham-operated group and ligation of the right hepatic lobes during reperfusion. It compared 30 and 60 min ischemia to 2 h reperfusion. The second experiment included a sham-operated group for every time point, and the right hepatic lobes were not ligated during reperfusion; a 30-min ischemia group was compared to 2-, 5-, and 24-h reperfusion groups. Total RNA from the ischemic lobes was analyzed by Northern hybridization for hsp70, albumin, AGP, and C/EBPalpha and beta. C/EBPalpha and beta proteins were compared by Western blotting. Differences in experimental design played an important role in interpretation of results. hsp70 mRNA began to increase during ischemia. Albumin mRNA remained constant during ischemia and reperfusion. The ischemic hepatocyte nucleus is not quiescent and retains the ability to upregulate certain genes, e.g., hsp70. Changes in mRNA in response to hepatic ischemia/reperfusion occur rapidly. Hepatic ischemia/reperfusion does not recapitulate the classic acute phase response; albumin is not down regulated during reperfusion.

Regulation of the acute phase response genes alpha 1-acid glycoprotein and alpha 1-antitrypsin correlates with sensitivity to thermal injury

BACKGROUND

The response to thermal injury is a complex physiologic process requiring communication between sites of injury and distal target organs. The liver, one of these target organs, synthesizes a family of secretory proteins, the acute phase reactants (APRs), that carries out specific protective functions. This study investigates the response of positively regulated (alpha 1-acid glycoprotein and alpha 1-antitrypsin) and negatively regulated (albumin) APR genes to severe thermal injury in three rat strains with differing abilities to survive thermal stress.

METHODS

Age and weight matched male Buffalo, Sprague-Dawley, and Fischer 344, 12- to 16-week-old rats (275 to 325 gm) received a 40% total body surface area scald burn. Total RNA was isolated from livers at 0, 2, 5, 12, 24, and 48 hours. Northern blot hybridization was performed with 32P-labeled rat alpha 1-glycoprotein, rat albumin, and mouse alpha 1-antitrypsin cDNAs. Relative amounts of alpha 1-glycoprotein, alpha 1-antitrypsin, and albumin mRNAs were determined by means of densitometric analyses.

RESULTS

All three strains elicit both a positive and negative acute phase (AP) response. Significant differences were observed in the degree and kinetics between strains. Those more sensitive to thermal injury exhibited a more intense positive AP response and possibly a delayed recovery. The AP response between these strains correlates with the variation in ability to survive severe trauma.

CONCLUSIONS

The differences in the kinetics and intensity of induction of APR genes between Buffalo, Sprague-Dawley, and Fischer rat strains suggest that the least intense AP response and its timely recovery correlated with the ability to survive a severe thermal injury and that, conversely, the more intense and prolonged response correlated with sensitivity to severe thermal injury. We propose that this may be a basis for variation in survival to thermal injury.

Effect of thermal injury on the expression of transcription factors that regulate acute phase response genes: the response of C/EBP alpha, C/EBP beta, and C/EBP delta to thermal injury

BACKGROUND

Eukaryotic organisms possess natural defense mechanisms that protect against stress stimuli. One such mechanism is the activation of families of stress response genes (e.g., the acute phase response). Transcription of many of these genes is regulated by the leucine zipper or bZIP proteins (CCAAT binding/enhancer binding proteins [C/EBPs]). The aim of this study was to show that the C/EBP transcription factor genes respond to thermal injury.

METHODS

Age- and weight-matched male Buffalo, Sprague-Dawley, and Fischer 344 12- to 16-week-old rats (275 to 325 gm) received a 40% total body surface area scald burn. Total RNA was isolated from livers at 0, 2, 5, 12, 24, and 48 hours. Northern blot hybridization was performed with 32P-labeled C/EBP alpha, C/EBP beta, and C/EBP delta cDNAs. Relative amounts of each mRNA were determined by densitometric analyses. For Western analyses liver nuclear and cytoplasmic protein extracts were prepared from burned and control rats. Nuclear protein extracts were resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, blotted onto a PVDF membrane, and detected by using an enhanced chemiluminescence detection kit.

RESULTS

Expression of C/EBP genes is regulated in response to 40% total body surface area scald burn. A simultaneous decrease in C/EBP alpha and an increase in C/EBP beta and C/EBP delta mRNA levels occur in response to thermal injury. Western analyses detect changes in C/EBP alpha and C/EBP beta pool levels that suggest a differential regulation of these genes in response to thermal injury.

CONCLUSIONS

The responses of C/EBP alpha, C/EBP beta, and C/EBP delta are similar in Buffalo, Sprague-Dawley, and Fischer rats. The induced level, however, of C/EBP beta mRNA was highest in the Sprague-Dawley strain and lowest in the Buffalo strain and correlates well with the mortality of these strains. Because C/EBP beta is associated with the transactivation of stress response genes, this may explain the intensity of the response in the susceptible strains. This agrees with our hypothesis that the higher degree of sensitivity of the Sprague-Dawley rat to stress relative to the Buffalo strain may be due to inherently higher levels of factors such as C/EBP whose functions are associated with activation of stress response genes.

Evidence for posttranscriptional regulation of C/EBPalpha and C/EBPbeta isoform expression during the lipopolysaccharide-mediated acute-phase response

The mRNAs of the CCAAT/enhancer-binding trans-activator proteins (C/EBPalpha and C/EBPbeta) serve as templates for the differential translation of several isoforms which have specific transcriptional regulatory functions. By using an oligonucleotide corresponding to the C/EBP binding site of the mouse alpha1-acid glycoprotein promoter, we detected multiple forms of C/EBPalpha and C/EBP++ beta proteins in the mouse liver that have DNA-binding activity. By using specific antisera, we detected C/EBPalphas with molecular masses of 42, 38, 30, and 20 kDa that have DNA-binding activity. The pool levels of the 42- and 30-kDa isoforms were high in control nuclear extracts and decreased significantly after lipopolysaccharide (LPS) treatment. The binding activity and protein levels of the 20-kDa isoform are low in controls and increase dramatically after LPS treatment. C/EBPbeta isoforms with molecular masses of 35, 20, and 16 kDa were also detected. The 35-kDa pool level did not change whereas the 20-kDa isoform was strongly induced in response to LPS. Western (immunoblot) and Southwestern (DNA-protein) analyses show that p42 C/EBPalpha forms specific complexes with the alpha1-acid glycoprotein oligonucleotide in control nuclear extract and that p20 C/EBP beta forms complexes in LPS-treated liver. Our studies suggest that synthesis of specific C/EBPalpha and C/EBPbeta isoforms occurred in the normal liver in vivo and that LPS mediated a differential initiation and inhibition of translation at specific AUG sites within each mRNA. The qualitative and quantitative changes in C/EBPalpha and C/EBPbeta isoform pool levels suggest that LPS or an LPS-stimulated factor can regulate the selection of AUG start sites for both activation and repression of translation. This regulation appears to involve an LPS-mediated down-regulation of initiation at the first AUG codon of the 42-kDa C/EBPalpha and dramatic translational up-regulation at the fifth AUG codon of the 20-kDa C/EBPalpha and the third AUG codon of the 20-kDa C/EBPbeta. These regulatory events suggest the existence of proteins that may act as translational trans-acting factors.

Characterization of somatic cell hybrids exhibiting extinction of AFP, albumin and an AFP-HPRT transgene

We utilized an AFP-HPRT transgene, i.e. the HPRT coding sequences under the regulation of AFP enhancer and promoter sequences, to localize the AFP extinguisher locus in intertypic somatic cell hybrids (hepatoma X fibroblast). This hybrid gene construct, which directly links AFP regulation to a reversibly selective gene, enabled the selection of stably transfected cells which express AFP, as well as cells showing extinction of AFP. Mouse hepatoma cells stably transfected with and expressing the transgene were fused to human fibroblasts, and the resulting somatic cell hybrids were characterized using Southern, Northern and karyotypic analyses. That several hybrids exhibited the proper extinction of AFP, AFP-HPRT and albumin suggests coregulation of these genes by an extinguisher. Segregant lines derived from these hybrids were selected for the loss of extinguisher activity and for reexpression of the transgene. Karyotypic analysis of hybrid and segregant lines, exhibiting proper AFP, albumin and AFP-HPRT phenotypes, revealed that the presence of human chromosome 7 was most closely associated with the AFP-extinguished state. The hybrids generated in these studies now make it possible to isolate the sequences responsible for AFP and albumin extinction.

Regulation of retinoblastoma gene expression in a mouse mammary tumor model

We initiated studies to investigate the involvement of the murine retinoblastoma (RB) gene in mammary carcinogenesis using cell lines derived from mammary glands of irradiated mice. We found that the RB mRNA levels as well as the amounts of the nuclear phosphoprotein were significantly reduced as the cells progressed in vitro from non-tumorigenic to tumorigenic stages. To further investigate RB gene expression with cellular development and tumorigenicity, we transfected malignant cells with expression vectors containing the murine RB cDNA driven by either the SV40 or the mouse metallothionein promoter sequences. The neomycin resistant gene was included in both vectors and was used as a selective marker for the transfected cells. Cells with reduced levels of endogenous RB mRNA were stably transfected and showed increased expression of RB. In addition, the morphology of these cells were altered and their growth rates in culture were reduced. Injection of the transfected cells into host mice resulted in a delayed onset of tumors compared with nontransfected parental cells. Our studies provide experimental data to confirm that loss of RB gene activity is involved in neoplastic transformation of cells and support the multistep theory of carcinogenesis.

Developmental control of transcription of the CAT reporter gene by a truncated mouse alphafetoprotein gene regulatory region in transgenic mice

A truncated mouse alphafetoprotein (AFP) gene promoter/enhancer region was tested for its ability to regulate the expression of the Escherichia coli chloramphenicol acetyltransferase (CAT) reporter gene in the livers of transgenic mice. The AFP regulatory region lacked any AFP gene structural DNA, included one enhancer sequence together with the proximal promoter sequence, and an element believed to be responsible for the postnatal repression of AFP gene transcription. The neonatal livers of AFP/CAT transgenic mice showed a high level of CAT enzyme expression, which was dramatically reduced between 7 and 14 days after birth. The staining of liver sections with anti-CAT antibodies showed that this expression was limited to hepatocytes. In one lineage, reexpression of CAT in the adult liver could be achieved by restitutive proliferation of hepatocytes following partial hepatectomy or CCl4-induced necrosis; reexpression in young animals (3-4 weeks of age) was even greater. These studies show that a truncated AFP promoter/enhancer region functions in a tissue-specific and developmental stage-specific fashion, and may be used to control the expression of other genes in the livers of transgenic mice.

Pharmacological correction of neonatal lethal hepatic dysfunction in a murine model of hereditary tyrosinaemia type I

Hereditary tyrosinaemia type I, a severe autosomal recessive metabolic disease, affects the liver and kidneys and is caused by deficiency of fumarylacetoacetate hydrolase (FAH). Mice homozygous for a FAH gene disruption have a neonatal lethal phenotype caused by liver dysfunction and do not represent an adequate model of the human disease. Here we demonstrate that treatment of affected animals with 2-(2-nitro-4-trifluoro-methylbenzyol)-1,3-cyclohexanedione abolished neonatal lethality, corrected liver function and partially normalized the altered expression pattern of hepatic mRNAs. The prolonged lifespan of affected animals resulted in a phenotype analogous to human tyrosinaemia type I including hepatocellular carcinoma. The adult FAH-/- mouse will serve as useful model for studies of the pathophysiology and treatment of hereditary tyrosinaemia type I as well as hepatic cancer.

Activation of hepatic proliferation-associated transcription factors by lipopolysaccharide

BACKGROUND

The hepatic acute-phase response is the result of reprogramming of gene expression in the liver. Similar acute-phase responses occur in regenerating liver after partial hepatectomy and are preceded by increases in the expression of a set of transcriptional regulatory proteins that are encoded by "immediate-early" genes. The purpose of this study was to determine whether acute systemic inflammation after lipopolysaccharide injection induces hepatic immediate-early genes that are induced by partial hepatectomy.

METHODS

Two- to 4-month-old Balb/c mice received intraperitoneal Escherichia coli lipopolysaccharide (0111:B4; 100 micrograms), and total liver RNA, nuclear protein extracts, or total liver protein lysates were obtained at 0, 1, 3, 12, and 24 hours. RNA blot hybridization analysis was used to determine steady-state messenger RNA levels for c-jun, jun-B, jun-D, c-fos, fos-B, fra-1, nup475, and zif268. Specific nuclear protein-binding activity was determined by gel mobility shift assay. The protein c-Jun was detected by antibody-blocking experiments, and Jun-B was detected by gel supershift assay of the activating protein (AP-1) complex. Steady-state Jun-B levels were determined by immunoblot analysis.

RESULTS

Intraperitoneal injection of lipopolysaccharide is followed by induction (from fivefold to 13-fold) of c-jun, jun-B, c-fos, zif268, and nup475 messenger RNAs in the liver. Lipopolysaccharide induced increases in AP-1 and Zif268 consensus DNA-binding activity in mouse liver. The proteins c-Jun and Jun-B are detected in the AP-1 complex after administration of lipopolysaccharide.

CONCLUSIONS

The induction of hepatic immediate-early genes after lipopolysaccharide is similar to that that follows partial hepatectomy. These transcription factors likely have important roles in the reprogramming of gene expression that leads to the acute-phase response.

Analysis of the mechanism of glucocorticoid-mediated down regulation of the mouse alpha-fetoprotein gene

Regulation of alpha-fetoprotein gene expression by dexamethasone was examined in vivo and in vitro using primary mouse fetal liver cell cultures. Dexamethasone accelerates the developmental down regulation of AFP mRNA pools. However, treatment of primary fetal liver cells in culture does not reduce the AFP mRNA pool and may stabilize both AFP and albumin gene expression. These results indicate that in vivo the effect of dexamethasone may require interaction with another tissue or cell type. The mechanism of the dexamethasone mediated inhibition of AFP was examined by DNase I footprinting and transient expression assays. Two protein-binding regions of the proximal promoter (III and IV) show significant homology to the GRE consensus sequence. DNase I footprinting shows that only region IV can bind purified GR and competition with GRE oligonucleotides indicate that, using adult liver nuclear proteins, no GR is bound in either region. Nuclear protein from adrenalectomized mice show the same protection as controls. These results indicate that GR may not bind to the AFP proximal promoter in the adult. AFP promoter-CAT expression vectors were used to further examine the effect of dexamethasone on AFP expression. AFP promoter-CAT constructs were inhibited by 10(-6) M dexamethasone; while linking of an AFP enhancer to the promoter abolished the effect. We conclude that the in vitro effects on transiently expressed AFP directed expression vectors may be a function of vector structure and/or characteristics of the cells used whereas the in vivo effect may reflect normal regulatory mechanisms.

The histidyl-tRNA synthetase from Streptococcus equisimilis: overexpression in Escherichia coli, purification, and characterization

We describe the high-level expression of the Streptococcus equisimilis histidyl-tRNA synthetase gene (hisS) in Escherichia coli and the purification and characterization of the gene product. Due to a lack of an efficient E. coli ribosome binding sequence in the hisS gene, the coding region was fused in-frame to the expression vector pT7-7, thereby creating a fusion gene construct (pT7-7recIII), which is under the control of a strong bacteriophage T7 promoter. Another construct (pT-7recII) was used for low level expression of the native histidyl-tRNA synthetase (HisRS). The plasmids were electroporated into E. coli HB101, which already contained pGP1-2. After temperature induction, the fusion HisRS, which has an extra 15 amino acids between the initiator Met and the second amino acid, Lys, was expressed at a level of approximately 18% of total cell protein (approximately 50 mg/liter of bacterial culture). The fusion HisRS was purified to > 99% by a combination of anion exchange and cation exchange chromatography of the S100 fraction. The predicted MWs of the native and fusion proteins are 47,932 and 49,717, respectively. The mass of the active fusion HisRS was estimated to be 94,000 Da by Sephacryl S-200 gel filtration chromatography and 108,200 Da by nondenaturing PAGE. Both methods show that the functional enzyme is a dimer of two identical subunits. SDS-PAGE analysis of purified fusion HisRS with or without reduction showed a single band of M(r) = 53.7 kDa.

Molecular cloning, identification, and sequence of the hyaluronan synthase gene from group A Streptococcus pyogenes

The hyaluronan (HA) synthase of Group A Streptococci has been identified by transposon mutagenesis and deletion analysis. The genes for the HA synthase and a recently identified UDP-Glc dehydrogenase (Dougherty, B. A., and van de Rijn, I. (1993) J. Biol. Chem. 268, 7118-7124) reside on a contiguous stretch of 3.2-kilobase pair DNA that can direct HA biosynthesis in Enterococcus faecalis and Escherichia coli as well as mutant Streptococcus (DeAngelis, P. L., Papaconstantinou, J., and Weigel, P. H. (1993) J. Biol. Chem. 268, 14568-14571). The synthase contains 395 residues (calculated Mr = 45,063) and migrates on SDS-PAGE with a molecular mass of 42 kDa. E. coli K5, which synthesizes UDP-glucuronic acid for production of its endogenous capsular polysaccharide, can make HA if it contains a plasmid encoding the intact 42-kDa protein. E. coli SURE or chi 1448 cells containing the same construct, however, cannot produce HA since these strains cannot make both required sugar nucleotide precursors. The HA synthase is predicted to be an integral membrane protein with four membrane-associated helices, which is consistent with the location of the enzyme activity in Streptococci. There is significant homology between the HA synthase and the Rhizobium nodC gene product, an enzyme that synthesizes chitin-like oligomers. This is the first description at the molecular level of an enzyme shown to synthesize a glycosaminoglycan.

The differential induction of alpha 1-acid glycoprotein and serum amyloid A genes by heavy metals

We have investigated the differential regulation of the mouse (Balb/c) acute phase reactants, alpha 1-acid glycoprotein and serum amyloid A by heavy metals (Hg, Cd, Pb, Cu, Ni and Zn). Mice have two distinct alpha 1-acid glycoprotein mRNAs encoded by alpha 1-acid glycoprotein gene-1, (AGP-1) and alpha 1-acid glycoprotein gene-2 (AGP-2) and 3 distinct serum amyloid A mRNAs encoded by serum amyloid A gene-1, (SAA-1), serum amyloid A gene-2 (SAA-2) and serum amyloid A gene-3 (SAA-3). Using specific oligonucleotides as probes we have demonstrated that the AGP-1 and AGP-2 genes, and the SAA-1 and SAA-2 genes are differentially induced by heavy metals in the liver. At the peak of induction, AGP-2 mRNA is 80-100-fold higher than the AGP-1 mRNA level; the SAA-1 mRNA level is approx. 40-fold higher than SAA-2, and SAA-3 mRNA is not detected. A similar differential pattern of expression is observed in bacterial lipopolysaccharide mediated inductions. However, low levels of SAA-3 are also seen in this treatment. Adrenalectomy has no effect on the inductions by heavy metals of AGP-2 and the SAAs, indicating that the glucocorticoid receptor pathway may not function in this regulation. However, AGP-1 induction is significantly delayed, indicating that glucocorticoid may be essential for a rapid response to Hg. The liver is the major site of heavy metal induction of AGP and SAA genes; Hg induces AGP-1 and 2, and SAA-1 and 2 only in the liver. Our studies clearly show that the AGP and SAA genes belong to a subgroup of acute-phase reactants that respond to heavy metals. CRP is another member of this family. Furthermore, our data suggest that the mechanism is not directly mediated by glucocorticoid or cytokine induction pathways.

trans-activation of the alpha 1-acid glycoprotein gene acute phase responsive element by multiple isoforms of C/EBP and glucocorticoid receptor

alpha 1-Acid glycoprotein (AGP) is a major acute phase protein synthesized primarily by the liver. The AGP gene is transcriptionally activated in hepatocytes during the acute phase response to bacterial lipopolysaccharide. In this study, we analyzed an acute phase responsive element (APRE) located between nucleotide residues -127 to -104 relative to the transcription initiation site of the mouse AGP gene. Binding studies show that several trans-acting factors interact with the APRE. Using monospecific antibodies we demonstrate that three isoforms of the CCAAT/enhancer-binding protein (C/EBP) family, namely C/EBP alpha, C/EBP beta, and C/EBP delta, bind to the APRE. Furthermore, with liver nuclear protein from control animals, C/EPB alpha is the predominant form that binds to the APRE, whereas with nuclear proteins from acute phase-induced animals, C/EBP alpha is replaced by C/EBP beta. The mechanism of activation of the AGP gene during the acute phase response appears to involve an exchange of C/EBP alpha by C/EBP beta. C/EBP delta does not play a role in this reaction. Interestingly, the C/EBP binding site of the APRE partially overlaps a functional glucocorticoid responsive element. We present evidence that both purified C/EBP alpha and glucocorticoid receptor bind strongly to the APRE. By site-specific mutation, we have identified the C/EBP and glucocorticoid receptor binding sites in the APRE. These mutants were used in expression vectors to demonstrate that both C/EBP and glucocorticoid receptor are essential for maximal response to interleukin-6 and dexamethasone. These results demonstrate that the APRE is a composite binding site for multiple factors that are responsible for the transcriptional control of the mouse AGP. Finally, functional analyses indicate that C/EBP alpha, C/EBP beta, and C/EBP delta are strong transcriptional trans-activators of the AGP APRE in hepatoma cells. These data suggest that the regulatory activity of the C/EBP with the APRE in the liver may require interactions with adjacent proteins.

Isolation of a Streptococcus pyogenes gene locus that directs hyaluronan biosynthesis in acapsular mutants and in heterologous bacteria

A contiguous 3-kilobase pair region of DNA was isolated from Group A Streptococcus pyogenes (GAS) that can direct hyaluronic acid (HA) capsule biosynthesis in acapsular mutants as well as heterologous bacteria. The DNA was identified by transposon 916 insertional mutagenesis and subcloned into a plasmid shuttle vector. Mutant acapsular GAS or Enterococcus faecalis containing this plasmid, but not vector alone, displayed a mucoid phenotype on agar plates, possessed a capsule as seen by light microscopy, and produced HA in quantities comparable with wild-type GAS. The polysaccharide was shown to be authentic HA based on its recognition by a specific proteoglycan and its degradation by Streptomyces hyaluronate lyase. Escherichia coli with the complementing plasmid also produced HA but at only 10% of the level made by the above cells. E. coli minicell analysis showed that two proteins, 42 and 45 kDa, are expressed by the functional DNA insert. Deletion analysis of the insert in the minicells revealed that the 42-kDa protein is essential for HA production. This is the first demonstration of reconstitution of HA capsule biosynthesis in vivo.

A sequential staining technique for karyotypic analysis of interspecific somatic cell hybrids

We describe a sequential staining technique for the karyotypic analysis of interspecific mouse x human somatic cell hybrids. Fluorescence in situ hybridization of samples, previously stained using standard trypsin/Giemsa protocols, was instrumental in the identification of human chromosomes present in hybrid lines. This procedure not only provided a simple distinction between human and mouse chromosomes, but it also allowed the visualization and monitoring of human sequences present in interspecific translocations and subchromosomal fragments.

Molecular cloning, sequence, structural analysis and expression of the histidyl-tRNA synthetase gene from Streptococcus equisimilis

The histidyl-tRNA synthetase gene (hisS) from Streptococcus equisimilis was cloned and sequenced. The gene for this aminoacyl-tRNA synthetase has an open reading frame of 1278 nucleotides. The deduced amino acid sequence encodes a protein of 426 amino acids with MW = 47,932. The protein is predicted to be soluble with a pl = 5.27. The protein sequence has extensive overall identity/similarity with the Escherichia coli and the yeast histidyl-tRNA synthetases (approximately 58% and approximately 20%, respectively). A putative promoter for gene transcription lies within two hundred nucleotides of the polypeptide start codon. The enzyme was overexpressed, to a level of about 18% of total cellular protein, as a fusion protein (containing an additional 15 amino acids) in E. coli using the pT7 expression system containing the T7 RNA polymerase/promoter (Tabor and Richardson, Proc. Natl. Acad. Sci. U.S.A. 82:1074-1078, 1985). The predicted MW for the hisS gene product is in good agreement with the size of the fusion protein determined by SDS-PAGE (M(r) = 53,700). Amino acid sequencing of the intact fusion protein and proteolytic fragments confirmed the deduced sequence of the synthetase at many positions throughout the protein. The expressed protein catalyzed the specific aminoacylation of tRNA(His) in vitro.

Posttranscriptional regulation of albumin and alpha-fetoprotein messenger RNA by transforming growth factor-beta 1 requires de novo RNA and protein synthesis

Transforming growth factor-beta (TGF beta) has been implicated in the regulation of hepatocyte function. We have examined TGF beta 1 regulation of albumin and alpha-fetoprotein (AFP) mRNA levels in a well differentiated mouse hepatoma cell line (BWTG3). TGF beta 1 reversibly decreased steady state mRNA levels of both albumin and AFP. By nuclear run-on assays, we found that TGF beta 1 caused no significant change in transcription rates for albumin or AFP. Pretreatment with actinomycin-D prevented the TGF beta 1-induced decrease in albumin and AFP mRNA levels. Also, if cells were treated with actinomycin-D after a 12-h exposure to TGF beta 1, actinomycin-D abrogated the further decrease in albumin and AFP mRNA levels that occurred after treatment with TGF beta 1 alone. Cycloheximide pretreatment blocked the TGF beta 1-induced decrease in albumin and AFP mRNA levels. TGF beta 1 altered neither the rate of BWTG3 cell growth nor the levels of mRNA for the growth-associated protooncogene c-myc. These data suggest that TGF beta 1 has regulatory effects on specific hepatocyte functions that are independent of growth regulatory effects. The decrease in albumin and AFP mRNAs caused by TGF beta 1 is posttranscriptional and dependent upon de novo RNA and protein synthesis.

Functional analysis of the mouse alpha-fetoprotein enhancers and their subfragments in primary mouse hepatocyte cultures

We have compared the activities of mouse alpha-fetoprotein (AFP) enhancers I, II, and III with their minimal enhancer fragments (Mers) I, II, and III and with the entire 7-kilobase pair enhancer domain by transient expression assay in primary fetal mouse liver cells. The level of expression directed by the AFP promoter [p(-1009)AFPcat] alone is stimulated at least 10-fold by the entire AFP enhancer domain (-1009 to -6983). Enhancer I can drive the level of chloramphenicol acetyltransferase activity equivalent to that of the entire enhancer domain, whereas the increase in activity by enhancers II and III is significantly lower (1.5-fold). MersI, II, and III all mediate a greater increase in activity than their corresponding enhancer regions. The increase with MerI is 16-fold. Using DNase I protection analyses we identified 3 protein-binding regions in MerI; site Ia binds liver and brain nuclear proteins; site Ib binds liver, kidney, and brain nuclear proteins as well as purified C/EBP; site Ic binds liver and kidney nuclear proteins. Site-specific mutation of Ia, Ib, or Ic showed a 10-25% reduction in chloramphenicol acetyltransferase expression; deletion of the C/EBP-binding site in Ib showed a 45% reduction in activity and mutation of all 3 sites (Ia, Ib, and Ic) resulted in a 75% reduction in activity. Our studies indicate no single trans-acting factor is absolutely essential for enhancer activity, and that the enhancer activity of MerI is mediated via a combinatorial and additive mechanism.

α-Fetoprotein expression in fetal kidney cells does not require enhancers

Expression of the alpha-fetoprotein (AFP) and albumin genes was examined in fetal mouse kidney by analysis of tissue mRNA pool sizes during development and transient expression assays in primary kidney tissue culture cells. AFP is expressed at a much lower level in kidney than in liver but transcription of the gene is activated early during development and repressed after birth with a time-course similar to liver. However, albumin mRNA was not detected in fetal or new born mouse kidney. Transient expression assays using AFP- and albumin-CAT (chloramphenicol acetyl transferase) vectors were employed to characterize cis-acting elements active in the regulation of AFP expression in kidney. Primary fetal liver and kidney cells in culture were used for these assays. The AFP promoter is active in kidney cells and the information necessary for tissue specific expression and developmental repression are contained within the first 1.0 kb of 5' flanking sequences of the AFP gene. In addition, the AFP upstream enhancer elements are inactive in primary kidney cells. The mouse albumin promoter is shown to be inactive in kidney cells. The results obtained using transient expression assays are consistent with the observed low level of AFP expression, developmental repression of AFP, and the absence of expression of albumin in the mouse kidney.

Interaction of acute-phase-inducible and liver-enriched nuclear factors with the promoter region of the mouse alpha 1-acid glycoprotein gene-1

The synthesis and secretion of several acute-phase proteins increases markedly following physiological stress. alpha 1-Acid glycoprotein (AGP), a major acute-phase reactant made by the liver, is strongly induced by inflammatory agents such as lipopolysaccharide (LPS). Nuclear run-on assay showed a 17-fold increase in the rate of AGP transcription 4 h following LPS injection. DNase I footprinting assays revealed multiple protein binding domains in the mouse AGP-1 promoter region. Region B (-104 to -91) is protected by a liver-enriched transcription factor that is heat labile and in limiting quantity. An adjacent region, C (-125 to -104), is well-protected by nuclear extracts from hepatocytes. Electrophoretic mobility shift assays indicated that only one DNA-protein complex can form with an oligonucleotide corresponding to region B. However, nuclear proteins from untreated mouse liver can form three strong complexes (C1, C2, and C3) and a weak one (C4) with oligonucleotide C. An acute-phase-inducible DNA-binding protein (AP-DBP) forms complex 4. A dramatic increase (over 11-fold) in AP-DBP binding activity is seen with nuclear proteins from LPS-stimulated animals. Interestingly, AP-DBP, a heat-stable factor, can form heterodimers with the transcription factor CCAAT/enhancer binding protein (C/EBP). Furthermore, purified C/EBP also binds avidly to region C. Our studies indicate that several liver-enriched nuclear factors can interact with AGP-1 promoter and that AP-DBP binds to the AGP-1 promoter with high affinity only during the acute-phase induction.

The effects of burn injury on the acute phase response

The time course of changes in the levels of acute-phase-reactant (APR) mRNAs in different tissues of rats with a 10% or a 60% total-body-surface-area (TBSA) burn and the relationship between the induction of APRs and the host's tolerance to thermal injury were studied. The acute phase response in a LPS-induced inflammation model and a burn-plus-LPS model were compared. The results of this study indicated that (1) the major site of APR synthesis is the liver; (2) even a small surface burn injury can elicit a rapid acute phase response, but the intensity of APR expression increases with the severity of the burn; (3) the down regulation of albumin mRNA, which is characteristic of the acute phase response, does not occur even though transferrin (Trf) mRNA levels are significantly decreased; (4) the resistant strain of inbred rats showed higher levels of alpha 1-antitrypsin (AT) mRNA before and after burn injury, indicating its contribution to the host's tolerance to thermal injury; (5) the increases in alpha 1-acid glycoprotein (AGP) and AT expressions are limited in the burn-plus-LPS rat model compared with either the burn model or LPS-stimulated model alone.

Differential expression of three C/EBP isoforms in multiple tissues during the acute phase response

Eucaryotic organisms possess natural defense processes triggered by stress factors such as injury, infection, and inflammation. The acute phase response is an early defense mechanism during which striking changes in protein synthesis occur in the liver and other tissues. The altered expression of many acute phase protein genes is at the transcriptional level. Some of these genes have DNA binding sites for the CCAAT/enhancer binding protein (C/EBP) family of transcription factors. We report here that in vivo expression of three isoforms of C/EBP is dramatically changed during the acute phase response. The steady-state mRNA levels of C/EBP alpha decreased significantly in the liver, lung, and fat tissues of lipopolysaccharide (LPS)-treated mice; moreover, nuclear run-off transcription assays indicated a decrease in the rate of C/EBP alpha gene transcription in isolated liver nuclei. The steady-state levels of C/EBP beta and a new isoform, C/EBP delta, were dramatically increased in many tissues within 4 h following LPS treatment. The rates of transcription of these two genes were only minimally altered in liver but significantly increased in kidney nuclei isolated from stimulated animals. Thus, the C/EBP isoforms exhibit differential mechanisms in their responses to LPS in various tissues and are likely to play an important role in mediating the transcriptional activation of genes involved in the acute phase response.

Functional analysis of the trans-acting factor binding sites of the mouse alpha-fetoprotein proximal promoter by site-directed mutagenesis

The trans-acting factors of the mouse alpha-fetoprotein proximal promoter (-202 base pairs) are aligned as follows: regions Ia (HNF-1), Ib (C/EBP), II (NF-1 or C/EBP), II' (NF-1 or HNF-1), III (NP-III), IV (NP-IV), Va (NP-Va), and Vb (C/EBP). Site-specific mutation abolished protein binding to the corresponding mutated site with the exception of the NF-1 site, in which mutation causes partial protection. Transient expression analyses indicate that chloramphenicol acetyl-transferase (CAT) activity is reduced by mutations in regions Ia, II', Ib, II, and IV. Mutation of region III causes an increased activity and mutation of regions Va and Vb shows a slight inhibitory effect. Linking alpha-fetoprotein enhancer I to the wild type promoter resulted in a 12-fold stimulation of CAT activity. The activity of promoters with mutated C/EBP-binding sites (Ib, II, and Vb), was slightly above controls, indicating that enhancer I can reverse the effect of these mutations. Inhibition or stimulation of promoter activity resulting from mutations of the HNF-1 or NP-III binding sites, respectively, persisted when enhancer I was linked to the promoters, indicating that enhancer I cannot rescue these mutations. Mutation of both HNF-1-binding sites resulted in greater than 90% inhibition of CAT expression with and without enhancer I, indicating these sites are essential for promoter activity. The stimulation of promoter activity by mutation of the NP-III site suggests that this site may be essential for repression or attenuation of the alpha-fetoprotein gene. Our studies indicate that regulation of the alpha-fetoprotein gene requires the combinatorial effect of multiple cis- and trans-acting elements in the proximal promoter and that enhancer I may provide a factor(s) that specifically rescue the promoter from the inhibitory effect of mutation in the C/EBP-binding sites.