alpha-synuclein binds to Tau and stimulates the protein kinase A-catalyzed tau phosphorylation of serine residues 262 and 356

alpha-Synuclein has been implicated in the pathogenesis of several neurodegenerative disorders based on the direct linking of missense mutations in alpha-synuclein to autosomal dominant Parkinson's disease and its presence in Lewy-like lesions. To gain insight into alpha-synuclein functions, we have investigated whether it binds neuronal proteins and modulates their functional state. The microtubule-associated protein tau was identified as a ligand by alpha-synuclein affinity chromatography of human brain cytosol. Direct binding assays using (125)I-labeled human tau40 demonstrated a reversible binding with a IC(50) about 50 pM. The interacting domains were localized to the C terminus of alpha-synuclein and the microtubule binding region of tau as determined by protein fragmentation and the use of recombinant peptides. High concentrations of tubulin inhibited the binding between tau and alpha-synuclein. Functionally, alpha-synuclein stimulated the protein kinase A-catalyzed phosphorylation of tau serine residues 262 and 356 as determined using a phospho-epitope-specific antibody. We propose that alpha-synuclein modulates the phosphorylation of soluble axonal tau and thereby indirectly affects the stability of axonal microtubules.

Immunocytochemical and immunoelectron microscopic localization of α-, β-, and γ-ENaC in rat kidney

Epithelial sodium channel (ENaC) subunit (α, β, and γ) mRNA and protein have been localized to the principal cells of the connecting tubule (CNT), cortical collecting duct (CCD), and outer medullary collecting duct (OMCD) in rat kidney. However, the subcellular localization of ENaC subunits in the principal cells of these cells is undefined. The cellular and subcellular localization of ENaC subunits in rat kidney was therefore examined. Immunocytochemistry demonstrated the presence of all three subunits in principal cells of the CNT, CCD, OMCD, and IMCD. In cortex and outer medulla, confocal microscopy demonstrated a difference in the subcellular localization of subunits. α-ENaC was localized mainly in a zone in the apical domains, whereas β- and γ-ENaC were found throughout the cytoplasm. Immunoelectron microscopy confirmed the presence of ENaC subunits in both the apical plasma membrane and intracellular vesicles. In contrast to the labeling pattern seen in cortex, α-ENaC labeling in IMCD cells was distributed throughout the cytoplasm. In the urothelium covering pelvis, ureters, and bladder, immunoperoxidase and confocal microscopy revealed differences the presence of all ENaC subunits. As seen in CCD, α-ENaC was present in a narrow zone near the apical plasma membrane, whereas β- and γ-ENaC were dispersed throughout the cytoplasm. In conclusion, all three subunits of ENaC are expressed throughout the collecting duct (CD), including the IMCD as well as in the urothelium. The intracellular vesicular pool in CD principal cells suggests ENaC trafficking as a potential mechanism for the regulation of Na+ reabsorption.

Obesity-related cardiovascular risk factors after weight loss: a clinical trial comparing gastric bypass surgery and intensive lifestyle intervention

OBJECTIVE

Weight reduction improves several obesity-related health conditions. We aimed to compare the effect of bariatric surgery and comprehensive lifestyle intervention on type 2 diabetes and obesity-related cardiovascular risk factors.

DESIGN

One-year controlled clinical trial (ClinicalTrials.gov identifier NCT00273104).

METHODS

Morbidly obese subjects (19-66 years, mean (s.d.) body mass index 45.1 kg/m(2) (5.6), 103 women) were treated with either Roux-en-Y gastric bypass surgery (n=80) or intensive lifestyle intervention at a rehabilitation centre (n=66). The dropout rate within both groups was 5%.

RESULTS

Among the 76 completers in the surgery group and the 63 completers in the lifestyle group, mean (s.d.) 1-year weight loss was 30% (8) and 8% (9) respectively. Beneficial effects on glucose metabolism, blood pressure, lipids and low-grade inflammation were observed in both groups. Remission rates of type 2 diabetes and hypertension were significantly higher in the surgery group than the lifestyle intervention group; 70 vs 33%, P=0.027, and 49 vs 23%, P=0.016. The improvements in glycaemic control and blood pressure were mediated by weight reduction. The surgery group experienced a significantly greater reduction in the prevalence of metabolic syndrome, albuminuria and electrocardiographic left ventricular hypertrophy than the lifestyle group. Gastrointestinal symptoms and symptomatic postprandial hypoglycaemia developed more frequently after gastric bypass surgery than after lifestyle intervention. There were no deaths.

CONCLUSIONS

Type 2 diabetes and obesity-related cardiovascular risk factors were improved after both treatment strategies. However, the improvements were greatest in those patients treated with gastric bypass surgery.

Characterization of an epithelial approximately 460-kDa protein that facilitates endocytosis of intrinsic factor-vitamin B12 and binds receptor-associated protein

By using receptor-associated protein (RAP) as an affinity target, an intrinsic factor-vitamin B12 (IF-B12)-binding renal epithelial protein of approximately 460 kDa was copurified together with the transcobalamin-B12-binding 600-kDa receptor, megalin. IF-B12 affinity chromatography of renal cortex membrane from rabbit and man yielded the same approximately 460-kDa protein. Binding studies including surface plasmon resonance analyses of the protein demonstrated a calcium-dependent and high affinity binding of IF-B12 to a site distinct from the RAP binding site. The high affinity binding of IF-B12 was dependent on complex formation with vitamin B12. Light and electron microscope autoradiography of rat renal cortex cryosections incubated directly with IF-57Co-B12 and rat proximal tubules microinjected in vivo with the radioligand demonstrated binding of the ligand to endocytic invaginations of proximal tubule membranes followed by endocytosis and targeting of vitamin B12 to lysosomes. Polyclonal antibodies recognizing the approximately 460-kDa receptor inhibited the uptake. Immunohistochemistry of kidney and intestine showed colocalization of the IF-B12 receptor and megalin in both tissues. In conclusion, we have identified the epithelial IF-B12-binding receptor as a approximately 460-kDa RAP-binding protein facilitating endocytosis.

Branhamella catarrhalis respiratory infections

Branhamella catarrhalis, a normal commensal of the oropharynx, is increasingly recognized as an important cause of bronchitis and bacterial pneumonia. Six patients with B. catarrhalis pneumonia documented by transtracheal aspirate or blood culture were studied, and 429 previously reported cases of B. catarrhalis bronchitis and pneumonia were reviewed. The mean age of patients with B. catarrhalis infection was 64.8 years, and preexisting chronic obstructive pulmonary disease was common. The typical clinical picture was that of purulent tracheobronchitis; patients with pneumonia were not severely ill and differed from those with bronchitis mainly by the presence of patchy lower-lobe infiltrates on chest roentgenogram. Fifty-three percent of reported strains produced beta-lactamase. Thirty-nine percent of the cultures were mixed, predominantly with Haemophilus influenzae and Streptococcus pneumoniae. The microbiologic, immunologic, and clinical features of B. catarrhalis infection, as well as the antimicrobial susceptibilities of this organism, were reviewed. The reasons for the lack of recognition of this common pathogen and possible solutions were considered.

Binding of Abeta to alpha- and beta-synucleins: identification of segments in alpha-synuclein/NAC precursor that bind Abeta and NAC

NAC, a 35-residue peptide derived from the neuronal protein alpha-synuclein/NAC precursor, is tightly associated with Abeta fibrils in Alzheimer's disease amyloid, and alpha-synuclein has recently been shown to bind Abeta in vitro. We have studied the interaction between Abeta and synucleins, aiming at determining segments in alpha-synuclein that can account for the binding, as well as identifying a possible interaction between Abeta and the beta-type synuclein. We report that Abeta binds to native and recombinant alpha-synuclein, and to beta-synuclein in an SDS-sensitive interaction (IC50 approx. 20 microM), as determined by chemical cross-linking and solid-phase binding assays. alpha-Synuclein and beta-synuclein were found to stimulate Abeta-aggregation in vitro to the same extent. The synucleins also displayed Abeta-inhibitable binding of NAC and they were capable of forming dimers. Using proteolytic fragmentation of alpha-synuclein and cross-linking to 125I-Abeta, we identified two consecutive binding domains (residues 1-56 and 57-97) by Edman degradation and mass spectrometric analysis, and a synthetic peptide comprising residues 32-57 possessed Abeta-binding activity. To test further the possible significance in pathology, alpha-synuclein was biotinylated and shown to bind specifically to amyloid plaques in a brain with Alzheimer's disease. It is proposed that the multiple Abeta-binding sites in alpha-synuclein are involved in the development of amyloid plaques.

Mannose 6-phosphate/insulin-like growth factor-II receptor targets the urokinase receptor to lysosomes via a novel binding interaction

The urokinase-type plasminogen activator receptor (uPAR) plays an important role on the cell surface in mediating extracellular degradative processes and formation of active TGF-beta, and in nonproteolytic events such as cell adhesion, migration, and transmembrane signaling. We have searched for mechanisms that determine the cellular location of uPAR and may participate in its disposal. When using purified receptor preparations, we find that uPAR binds to the cation-independent, mannose 6-phosphate/insulin-like growth factor-II (IGF-II) receptor (CIMPR) with an affinity in the low micromolar range, but not to the 46-kD, cation-dependent, mannose 6-phosphate receptor (CDMPR). The binding is not perturbed by uPA and appears to involve domains DII + DIII of the uPAR protein moiety, but not the glycosylphosphatidylinositol anchor. The binding occurs at site(s) on the CIMPR different from those engaged in binding of mannose 6-phosphate epitopes or IGF-II. To evaluate the significance of the binding, immunofluorescence and immunoelectron microscopy studies were performed in transfected cells, and the results show that wild-type CIMPR, but not CIMPR lacking an intact sorting signal, modulates the subcellular distribution of uPAR and is capable of directing it to lysosomes. We conclude that a site within CIMPR, distinct from its previously known ligand binding sites, binds uPAR and modulates its subcellular distribution.

Human calumenin localizes to the secretory pathway and is secreted to the medium

Calumenin belongs to a family of multiple EF-hand proteins that include reticulocalbin, ERC-55, and Cab45. Reticulocalbin and ERC-55 localize to the ER due to a C-terminal HDEL retrieval signal. Cab45 contains a HEEF C-terminal sequence and is localized to the Golgi apparatus. The murine homologue of calumenin is reported to be present in the ER due to a C-terminal HDEF retrieval signal. The human homologue differs from the murine at 7 amino acid positions but the HDEF signal is conserved. However, in the cultured human cell lines, HaCaT keratinocytes, normal and transformed MRC-5 fibroblasts, as well as in transfected COS-1 cells, human calumenin could be demonstrated in the ER as well as in the Golgi complex. Especially in MRC-5 cells, a certain heterogeneity was observed, with some of the cells having calumenin localized solely to the ER while in other cells calumenin could be demonstrated in the ER as well as in the Golgi complex. Immunoelectron microscopy of placental syncytiotrophoblast cells showed that a substantial fraction of calumenin is localized in close association with the ER membrane. In addition, the protein may be recovered from the medium of cultured cells in an endoglycosidase H-resistant form, suggesting that the glycosylated protein has been further modified in the Golgi apparatus and secreted to the medium.

Physiology and pathophysiology of renal aquaporins

The discovery of aquaporin-1 (AQP1) by Agre and associates answered the longstanding biophysical question of how water specifically crosses biological membranes. In the kidney at least 7 aquaporins are expressed at distinct sites. AQP1 is extremely abundant in the proximal tubule and descending thin limb and is essential for urinary concentration. AQP2 is exclusively expressed in the principal cells of the connecting tubule and collecting duct and is the predominant vasopressin-regulated water channel. AQP3 and AQP4 are both present in the basolateral plasma membrane of collecting duct principal cells and represent exit pathways for water reabsorbed apically via AQP2. Studies in patients and transgenic mice have shown that both AQP2 and AQP3 are essential for urinary concentration. Three additional aquaporins are present in the kidney. AQP6 is present in intracellular vesicles in collecting duct intercalated cells and AQP8 are present intracellularly at low abundance in proximal tubules and collecting duct principal cells but the physiological function of these 2 channels remain undefined. AQP7 is abundant in the brush border of proximal tubule cells and is likely to be involved in proximal tubule water reabsorption. A series of studies have underscored crucial roles of aquaporins for regulation of renal water metabolism and hence body water balance. Moreover it has become clear that dysregulation of aquaporins, and especially AQP2 is critically involved in many water balance disorders. Lack of functional AQP2 is seen in primary forms of diabetes insipidus, and reduced expression and targeting is seen in several diseases associated with urinary concentrating defects such as acquired nephrogenic diabetes insipidus, postobstructive polyuria, as well as acute and chronic renal failure. In contrast, in conditions with water retention such as severe congestive heart failure, pregnancy and SIADH both AQP2 expression levels and apical plasma membrane targetting is increased suggesting a role for AQP2 in the development of water retention. Continued analysis of the aquaporins is providing detailed molecular insight into the fundamental physiology and pathophysiology of water balance and water balance disorders.

Semliki forest virus: cause of a fatal case of human encephalitis

A fatal case of human encephalitis has been observed for which our results indicate that Semliki Forest virus (SFV) was the etiologic agent. This is surprising in view of the fact that this virus, which has been widely studied, was believed to be one of the arboviruses nonpathogenic for man. Described are the clinical course, the virological examinations performed, and the histopathological findings in the central nervous system.

Localization of aquaporin-7 in rat and mouse kidney using RT-PCR, immunoblotting, and immunocytochemistry

To establish the segmental, cellular, and subcellular localization of AQP7 in rat and mouse kidney, we used RT-PCR, immunocytochemical, and immunoblotting approaches. RT-PCR of rat and mouse kidney zones revealed AQP7 mRNA in cortex and outer stripe of the outer medulla. RT-PCR on microdissected nephron segments revealed AQP7 mRNA in proximal convoluted and straight tubules. Immunoblotting using peptide-derived rabbit antibodies to either rat or mouse AQP7 revealed a 28-kDa band in kidney and testes from rat and mouse, respectively. Immunocytochemistry revealed strong AQP7 labeling of segment 3 proximal tubules and weaker labeling of proximal convoluted tubules in both rat and mouse kidneys. The labeling was almost exclusively confined to the brush border with no basolateral labeling. No labeling was observed of thin descending limbs or collecting duct. Immunolabeling controls were negative. The presence of AQP7 in the proximal tubule brush border indicates a role of AQP7 in proximal tubule water reabsorption.

miR-151a induces partial EMT by regulating E-cadherin in NSCLC cells

miR-151a and its host gene, focal adhesion kinase, FAK, are located in a region of chromosome 8q that is frequently amplified in solid tumors, including lung cancer. Lung cancer is the leading cause of cancer deaths worldwide and metastasis remains the major challenge in battling lung cancer mortality. Here, we demonstrate that miR-151a is overexpressed in non-small cell lung cancer (NSCLC) patient specimens, as compared to healthy lung. In addition, miR-151a overexpression promotes proliferation, epithelial-to-mesenchymal transition (EMT) and induces tumor cell migration and invasion of NSCLC cells. Blocking miR-151a expression using anti-miR-151a approaches significantly reduced NCSLC cell proliferative and motility potential. Furthermore, we determined that miR-151a significantly regulates E-cadherin expression. Finally, functional rescue experiments determined that overexpression of E-cadherin in miR-151a NSCLC cell lines potently repressed miR-151a-induced partial EMT and cell migration of NSCLC cells. In conclusion, our findings suggest that miR-151a functions as an oncomiR in NSCLC by targeting E-cadherin mRNA and inducing proliferation, migration and partial EMT.

Molecular and functional evidence for electrogenic and electroneutral Na(+)-HCO(3)(-) cotransporters in murine duodenum

Inward Na(+)-HCO(3)(-) cotransport has previously been demonstrated in acidified duodenal epithelial cells, but the identity and localization of the mRNAs and proteins involved have not been determined. The molecular expression and localization of Na(+)-HCO(3)(-) cotransporters (NBCs) were studied by RT-PCR, sequence analysis, and immunohistochemistry. By fluorescence spectroscopy, the intracellular pH (pH(i)) was recorded in suspensions of isolated murine duodenal epithelial cells loaded with 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein. Proximal duodenal epithelial cells expressed mRNA encoding two electrogenic NBC1 isoforms and the electroneutral NBCn1. Both NBC1 and NBCn1 were localized to the basolateral membrane of proximal duodenal villus cells, whereas the crypt cells did not label with the anti-NBC antibodies. DIDS or removal of extracellular Cl(-) increased pH(i), whereas an acidification was observed on removal of Na(+) or both Na(+) and Cl(-). The effects of inhibitors and ionic dependence of acid/base transporters were consistent with both inward and outward Na(+)-HCO(3)(-) cotransport. Hence, we propose that NBCs are involved in both basolateral electroneutral HCO(3)(-) transport as well as basolateral electrogenic HCO(3)(-) transport in proximal duodenal villus cells.

Antibody-dependent enhancement of HIV-1 infection in human term syncytiotrophoblast cells cultured in vitro

We examined if Fc receptor-mediated antibody-dependent enhancement (FcR-ADE) or complement-mediated antibody-dependent enhancement (C'-ADE) of virus infection can contribute to increasing replication of HIV-1 in human syncytiotrophoblast (ST) cells. Here we report that both FcR-ADE and C'-ADE may result in enhanced virus release from HIV-1-infected ST cells. We show that FcR-ADE of HIV-1 infection in ST cells is mediated by FcRIII and other FcR(s) belonging to undetermined Fc classes and does not require CD4 receptors, whereas C'-ADE uses both CD4 and CR2-like receptors. FcR-ADE seems to be more efficient in enhancing HIV-1 replication than C'-ADE. While FcR-ADE leads to increased internalization of HIV-1, C'-ADE does not result in enhanced endocytosis of the virus. In addition, antibodies mediating FcR-ADE are reactive with the gp120 viral envelope antigen, whereas antibodies involved in C'-ADE react with the viral transmembrane glycoprotein gp41. Data suggest that both FcR-ADE and C'-ADE may contribute to the spread of HIV-1 from mother to the fetus.

Susceptibility of MHC class I expressing extravillous trophoblast cell lines to killing by natural killer cells

Purified human first trimester extravillous trophoblast (EVT) cell lines HTR-8 and HT-116 were examined for susceptibility to natural killer (NK) cell-mediated lysis. Based upon nucleic acid sequencing of an amplified fragment of cDNA, Western blot analysis and immunostaining of fixed and live cells, it was shown that both EVT cell lines expressed HLA-G mRNA and protein within the cytoplasm when cultured on laminin-coated plates. Very weak HLA-G expression was detectable on the cell surface under these conditions. However, strong cell surface expression of a classical MHC class I molecule (most likely HLA-C) was exhibited by these EVT cell lines when grown on laminin, as indicated by W6/32 FACS analysis (Ab recognizing pan MHC class I), and Western immunoblotting with HC10 (Ab recognizing HLA-B/C). When these EVT cells, cultured on laminin, were used as targets for peripheral blood natural killer (NK) cells in a standard chromium release assay, both HTR-8 and HT-116 cells were lysed by NK cells in a dose-dependent manner. The respective percentage specific lysis at an effector to target (E/T) ratio of 100 was 28+/-7, and 48+/-14. The choriocarcinoma cell lines JAR and JEG-3 which were respectively MHC class I negative and HLA-G positive were resistant to NK cell lysis. Thus, there was no clear relationship between the MHC class I expression and NK cell resistance or susceptibility among the EVT cell lines and choriocarcinoma cells. These findings raise the possibility that NK cells may take part in the surveillance of the invasive EVT cells during normal placentation.

The influence of corneal stromal matrix proteins on the migration of human corneal fibroblasts

Motivated by the alterations seen in the corneal matrix composition after photorefractive keratectomy and the migration of corneal keratocytes seen following this procedure, the locomotor response of corneal stromal fibroblasts to various extracellular matrix proteins was determined. In addition, the involvement of integrin mediated attachment to the matrix proteins was investigated. Quantitative invasion assays were performed using collagen gels, supplemented with either fibronectin, tenascin, collagen type V, collagen type VI, chondroitin sulfate or keratan sulfate. The ultrastructure of the gels was visualized by scanning electron microscopy and related to the migration results. The extent of alpha(1)beta(1), alpha(2)beta(1), alpha(3)beta(1)and alpha(5)beta(1)integrin mediated attachment to the matrix proteins was evaluated using blocking antibodies. Fibronectin increased corneal fibroblast migration significantly, and served as an excellent substrate for cellular attachment, mediated by the alpha(5)beta(1)integrin. Addition of tenascin to the fibronectin-containing gels disrupted these effects, while attachment to this matrix also involved the integrins alpha(2)beta(1)and alpha(3)beta(1). Chondroitin sulfate and collagen types V and VI primarily altered the structure of the collagen matrix, resulting in an inhibition of migration by the collagens and an increase by chondroitin sulfate. They all served as poor substrates for attachment. Thus, the migratory activity of corneal fibroblasts in vitro is influenced by the composition of the surrounding extracellular matrix, either by integrin mediated cell-matrix interactions or through matrix-matrix interactions. This study provides evidence that the provisional matrix deposited in a corneal stromal wound may facilitate the entry of migrating corneal fibroblasts.

High interferon alpha levels in placenta, maternal, and cord blood suggest a protective effect against intrauterine herpes simplex virus infection

Interferons (IFN) are produced by the placenta during pregnancy, and they can be detected in the maternal and fetal blood. Although the antiviral potential of IFNs is well established, it remains unclear whether the IFNs associated with pregnancy can prevent transplacental spread of viral infection. The present study was undertaken in order to determine the possible protective effect of placentally produced IFN-alpha on fetal acquisition of herpes simplex virus (HSV). Nine mothers with a known history of genital HSV infection were studied. In five cases IFN-alpha was detected in the placenta, maternal, and fetal blood, whereas in three cases IFN-alpha could not be detected. in the remaining case, IFN-alpha was found only in the maternal blood. As corroborated by the serological evidence of early HSV infection in the cord blood, the single case of vertical HSV transmission was observed in the group of IFN nonproducers. Furthermore, virus transmission did not occur in cases where IFN-alpha was present in the placenta and simultaneously in the maternal and fetal circulations. Thus, the present data indicate that high levels of IFN during pregnancy may protect the fetus from acquiring a possibly fatal intrauterine HSV infection.

Alanine aminotransferase in bovine brain: purification and properties

Mitochondrial and cytosolic alanine aminotransferases (EC 2.6.1.2) were partially purified (140- and 180-fold), respectively) from bovine brain cortex by means of (NH4)2SO4 precipitation, gel filtration on Sephadex G-150, and in-exchange chromatography on DEAE A-50 and characterized. The enzymes exhibited identical molecular weights (110,000 +/- 10,000) and pH optima (7.8), but were eluted from CM Sephadex C-50 at different ionic strengths. Isoelectric focusing of the enzymes indicated a pI value of 5.2 for the cytosolic enzyme and 7.2 for the mitochondrial enzyme. The Km values of the mitochondrial enzyme were 5.1 mM, 6.6 mM, 0.7 mM, and 0.4 mM and of the cytosolic isozyme were 30.3 mM, 4.3 mM, 0.7 mM, and 0.5 mM for alanine, glutamate, 2-oxoglutarate, and pyruvate, respectively. The results indicated that two forms of alanine aminotransferase exist in nerve tissue, which suggests that they may play different roles in the cellular metabolism of nerve tissue.

Epidemiology of an outbreak in a maternity unit of infections with an antigenic variant of Echovirus 11

After an 8-day-old child had died with clinical signs of septicemia, 6 other newborns fell ill. Virus was isolated from various sites from all the 6 children (28 isolations). The agent was identified by cross neutralization tests as an antigenic variant of Echovirus 11. The agent could not be isolated from mothers or nursery staff (49 people). We therefore tried to trace the path of infection by isolating specific IgM and IgG antibodies. A laboratory infection by the agent isolated enabled the time pattern of the serologic immune response to be roughly determined. The data collected indicate that the infection spread through close contact between the affected newborns and nurses working in the newborn room. Rigorous hygienic and isolation measures, initiated immediately, appeared to interrupt the spread of infection.

Interactions between human immunodeficiency virus type 1 and human cytomegalovirus in human term syncytiotrophoblast cells coinfected with both viruses

Human cytomegalovirus (HCMV) and human immunodeficiency virus type 1 (HIV-1) may interact in the pathogenesis of AIDS. The placental syncytiotrophoblast layer serves as the first line of defense of the fetus against viruses. We analyzed the patterns of replication of HIV-1 and HCMV in singly an dually infected human term syncytiotrophoblast cells cultured in vitro. Syncytiotrophoblast cells exhibited restricted permissiveness for HIV-1, while HCMV replication was restricted at the level of immediate-early and early gene products in the singly infected cells. We found that the syncytiotrophoblasts as an overlapping cell population could be coinfected with HIV-1 and HCMV. HIV-1 replication was markedly upregulated by previous or simultaneous infection of the cells with HCMV, whereas prior HIV-1 infection of the cells converted HCMV infection from a nonpermissive to a permissive one. No simultaneous enhancement of HCMV and HIV-1 expression was observed in the dually infected cell cultures. Major immediate-early proteins of HCMV were necessary for enhancement of HIV-1 replication, and interleukin-6 production induced by HCMV and further increased by replicating HIV-1 synergized with these proteins to produce this effect. Permissive replication cycle of HCMV was induced by the HIV-1 tat gene product. We were unable to detect HIV-1 (HCMV) or HCMV (HIV-1) pseudotypes in supernatant fluids from dually infected cell cultures. Our results suggest that interactions between HIV-1 and HCMV in coinfected syncytiotrophoblast cells may contribute to the transplacental transmission of both viruses.

The exon 3 encoded sequence of the intracellular serine proteinase inhibitor plasminogen activator inhibitor 2 is a protein binding domain

We have used a combination of biochemical and immunological methods to probe for proteins that interact with the cytoplasmic form of plasminogen activator inhibitor 2 (PAI-2) and to identify the structure in PAI-2 that mediates the binding. By affinity chromatography on immobilized PAI-2, we purified a collection of PAI-2-binding proteins. These proteins bound 125I-labeled PAI-2 in vitro (IC50, approximately 10-100 nM) in a calcium-independent reaction that did not abrogate the proteinase inhibitory function of PAI-2. Annexin I was identified among the eluted proteins, and purified annexins I, II, IV, and V, but not III and VI, possessed 125I-labeled PAI-2 binding activity. Immune precipitation by anti-PAI-2 monoclonal and polyclonal antibodies of metabolically labeled melanoma cells treated with a cleavable cross-linker prior to analysis revealed three prominent proteins with apparent masses of 100, 70, and 50 kDa. We localized the protein binding domain in PAI-2 between amino acid residues 66 and 98, as determined by using a PAI-2 mutant lacking this domain and a synthetic peptide spanning this region. This region of PAI-2 corresponds to exon 3 of the gene sequence thought to be critical for PAI-2 functions.