Human immunodeficiency virus type 1 Rev activation can be achieved without Rev-responsive element RNA if Rev is directed to the target as a Rev/MS2 fusion protein which tethers the MS2 operator RNA

The posttranscriptional trans activation of unspliced or partially spliced human immunodeficiency virus RNAs by the Rev regulatory protein is crucial for virus replication and is dependent on sequence-specific RNA binding by Rev. The cognate RNA target of Rev is contained within a highly structured, 244-nucleotide Rev-responsive element (RRE) RNA in the viral env gene. Here, we show that specific interaction with the RRE is not an absolute requirement for Rev function. When the RRE is replaced by a heterologous MS2 phage operator sequence, Rev will facilitate the cytoplasmic expression of human immunodeficiency virus mRNAs containing this sequence if directed to the MS2 operator via the RNA binding motif of the MS2 phage coat protein (MS-C) as a Rev/MS-C fusion protein. Rev/MS-C efficiently activated both RRE and MS2 targets. A mutation in the MS2 operator that abolished the coat protein binding in vitro rendered the mutant RNA nonresponsive to the fusion protein in vivo. Notwithstanding that Rev can be tethered to the viral RNAs via another RNA binding motif, the structural integrity of the N terminus of Rev was still required for optimal trans activation.

Rheumatoid cachexia: depletion of lean body mass in rheumatoid arthritis. Possible association with tumor necrosis factor

OBJECTIVE

To investigate body composition and serum tumor necrosis factor (TNF) levels in a series of 24 patients with rheumatoid arthritis (RA).

METHODS

Body composition assessment by anthropometric measures and bioelectrical impedance. Cytokine determination in serum by ELISA:

RESULTS

When compared to United States population norms, 16 of the subjects (67%) were cachectic. In regression models, lean body mass (LBM) was inversely associated with the number of swollen joints (p < 0.025). Elevated TNF-alpha was found in 3 of 5 flaring patients vs 0 of 18 patients with less active disease (p = 0.001). These 3 were all cachectic, while the 2 flaring patients without detectable TNF had normal LBM (p < 0.03). Among the whole group, there was a trend toward increasing disability with decreased LBM after adjusting for joint pain and disease duration (p < 0.07).

CONCLUSION

Cachexia is common in RA, and may be cytokine driven. Given the prognostic impact of LBM wasting in other diseases, the effect of rheumatoid cachexia on outcome in RA deserves further study.

A specific sequence with a bulged guanosine residue(s) in a stem-bulge-stem structure of Rev-responsive element RNA is required for trans activation by human immunodeficiency virus type 1 Rev

We demonstrate that both the in vitro RNA binding and in vivo trans activation functions of human immunodeficiency virus type 1 Rev regulatory protein Rev require the presence of a 9-nucleotide 5'-CACUAUGGG-3' RNA motif on its cognate target, the Rev-responsive element RNA. For optimal Rev recognition, this sequence must be presented as a stem-bulge-stem structure and must contain at least two G's, one of which must be unpaired, and include some or all of the CACUAU sequence upstream of the three G's. Distal mutations which result in the base pairing of the G's eliminate the Rev response. The first G is crucial, but changes at the other G's are tolerated if at least one G is unpaired. The secondary structure or the three-dimensional orientation of the B1 and B2 stem-loops of the Rev-responsive element are not relevant as long as the 5'-CACUAUGGG-3' sequence is preserved, with at least one bulged G residue.

Demonstration of chlamydial RNA and DNA during a culture-negative state

Trachoma is a common blinding disease of humans caused by ocular infections with Chlamydia trachomatis. The cynomolgus monkey is a valuable primate model for the detection, pathobiology, and treatment of this infection. We have used this model system to compare the relative ability of tissue culture, direct fluorescence cytology, a modified polymerase chain reaction, and RNA blotting to detect C. trachomatis following primary infection and reinfection over 34 weeks. Six cynomolgus monkeys were given a primary ocular chlamydia infection, and 20 weeks later they were reinoculated with the same organism. All animals showed brisk inflammatory responses to the primary infection and milder inflammatory reactions to reinfection. All four diagnostic techniques detected chlamydia at 1 week after primary infection, but both nucleic acid detection methods suggested that organisms were present longer after primary infection than did either tissue culture or direct fluorescence cytology (16 weeks for RNA blotting versus 12 weeks for tissue culture). Following reinoculation at 20 weeks, the period of C. trachomatis detection by tissue culture or direct fluorescence cytology (4 weeks) was much shorter than after primary infection. In contrast, nucleic acid detection was positive for up to 5 weeks longer than tissue culture or direct fluorescence cytology. Both polymerase chain reaction and RNA blotting, which involved no amplification step, indicated the presence of organisms during the culture-negative period. These data suggest that live chlamydiae may remain at a site of infection and produce inflammation beyond the time at which standard microbiological techniques are able to detect them.

Human immunodeficiency virus type 1 (HIV-1) provirus expression and LTR transcription are repressed in NEF-expressing cell lines

Human immunodeficiency virus type 1 (HIV-1) NEF protein has been demonstrated to be a negative regulator of HIV-1 replication and HIV-1 LTR transcription under transient expression conditions. The difficulty of several laboratories to reproduce these findings led us to reexamine the role of NEF in HIV-1 provirus expression and HIV-1 LTR transcription. Basal transcription from the HIV-1 LTR in the presence of a NEF expression vector was compared to that in the presence of a mutated NEF vector. NEF expression led to a greater than 10-fold repression of LTR transcription under these conditions. HeLa and Jurkat cell lines carrying the nef gene linked to the CMV promoter or the HIV-1 LTR were isolated by coselection for neomycin resistance. Single cell isolates were further selected for the expression of nef transcripts. With the exception of the anti-sense nef cell lines, all the nef cell lines expressed the 27-kDa NEF protein, detectable by immunoprecipitation. NEF+ HeLa cell lines were at least 5-fold less efficient than NEF- HeLa cell lines in transient proviral expression. Provirus expression was also repressed in the NEF+ Jurkat cell lines. TAT-activated LTR transcription from an HIV-1 LTR-linked CAT expression vector was repressed 10-fold in the NEF+ HeLa and NEF+ Jurkat cell lines. When infected with HIV-1, NEF expressing T lymphoid cell lines showed moderate delays in onset and peak of reverse transcriptase production. However, none of these cell lines completely arrested virus replication. Our data confirm a negative regulatory effect of NEF on both virus production and LTR driven CAT expression in the cell lines tested. It is possible that cell specific factors may influence NEF activity.

Human immunodeficiency virus rev protein recognizes a target sequence in rev-responsive element RNA within the context of RNA secondary structure

Human immunodeficiency virus type 1 Rev protein modulates the distribution of viral mRNAs from the nucleus to the cytoplasm by interaction with a highly structured viral RNA sequence, the Rev-responsive element (RRE). To identify the minimal functional elements of RRE, we evaluated mutant RREs for Rev binding in vitro and Rev response in vivo in the context of a Gag expression plasmid. The critical functional elements fold into a structure composed of a stem-loop A, formed by the ends of the RRE, joined to a branched stem-loop B/B1/B2, between bases 49 and 113. The 5' 132 nucleotides of RRE, RREDDE, which possessed a similar structure, bound Rev efficiently but were nonfunctional in vivo, implying separate binding and functional domains within the RRE. Excision of stem-loop A reduced Rev binding significantly and abolished the in vivo Rev response. The B2 branch could be removed without severe impairment of binding, but deletions in the B1 branch significantly reduced binding and function. However, deletion of 12 nucleotides, including the 5' strand of stem B, abolished both binding and function, while excision of the 3' strand of stem B only reduced them. Maintenance of the native RRE secondary structure alone was not sufficient for Rev recognition. Many mutations that altered the primary structure of the critical region while preserving the original RNA conformation were Rev responsive. However, mutations that changed a 5'..CACUAUGGG..3' sequence in the B stem, without affecting the overall structure abolished both in vitro Rev binding and the in vivo Rev response.

Detection and differentiation of Chlamydia trachomatis, Chlamydia psittaci, and Chlamydia pneumoniae by DNA amplification

The polymerase chain reaction was used to detect major outer membrane protein (MOMP) gene sequences from the three species of Chlamydia. Using three primer pairs and one restriction enzyme digestion, three distinct genotypes, corresponding to the three species, Chlamydia trachomatis, Chlamydia pneumoniae, and Chlamydia psittaci, were demonstrated. C. trachomatis was amplified by all three primer pairs and the amplified fragment was digested by EcoRI. C. pneumoniae was amplified by only two of the three primer pairs, and the amplified fragment was digested by EcoRI. C. psittaci was amplified by only two of the pairs and the amplified fragment was EcoRI-resistant. C. trachomatis was detected in direct patient specimens, tissue culture specimens, and fixed specimens, and all serovars of C. trachomatis were detectable. The polymerase chain reaction can detect and differentiate the three species of Chlamydia and may prove a valuable diagnostic tool.

The cDNA sequence of mouse LAMP-2. Evidence for two classes of lysosomal membrane glycoproteins

We describe the isolation and sequencing of a cDNA encoding the mouse lysosomal membrane glycoprotein mLAMP-2 and the sequence differences that distinguish this molecule from the LAMP-1 class of proteins. An oligonucleotide probe corresponding to the NH2-terminal amino acid sequence of purified mLAMP-2 was synthesized by the polymerase chain reaction and used to screen several cDNA libraries. cDNA clones with an insert of 1,700 nucleotides were identified and sequenced. The deduced amino acid sequence of mLAMP-2 comprises a signal sequence of 25 residues and a 390-amino acid polypeptide (Mr 43,017) with the following putative domains: a large intraluminal region (residues 1-354) with 17 N-linked glycosylation sites (Asn-X-Ser/Thr), a hydrophobic transmembrane-spanning region of 24 residues (355-378), and a COOH-terminal cytoplasmic tail of 12 residues (379-390). When this sequence is compared with those of other lysosomal membrane glycoproteins, it is apparent that mouse LAMP-2 and human LAMP-2 form one homology class (LAMP-2) that is separated from the LAMP-1 class of proteins. The sequence differences in these two classes provide a basis for comparing the structure of the proteins with their biochemical and biological properties.

The cDNA sequence of mouse Pgp-1 and homology to human CD44 cell surface antigen and proteoglycan core/link proteins

We describe the isolation and sequencing of a cDNA encoding mouse Pgp-1. An oligonucleotide probe corresponding to the NH2-terminal sequence of the purified protein was synthesized by the polymerase chain reaction and used to screen a mouse macrophage lambda gt11 library. A cDNA clone with an insert of 1.2 kilobases was selected and sequenced. In Northern blot analysis, only cells expressing Pgp-1 contained mRNA species that hybridized with this Pgp-1 cDNA. The nucleotide sequence of the cDNA has a single open reading frame that yields a protein-coding sequence of 1076 base pairs followed by a 132-base pair 3'-untranslated sequence that includes a putative polyadenylation signal but no poly(A) tail. The translated sequence comprises a 13-amino acid signal peptide followed by a polypeptide core of 345 residues corresponding to an Mr of 37,800. Portions of the deduced amino acid sequence were identical to those obtained by amino acid sequence analysis from the purified glycoprotein, confirming that the cDNA encodes Pgp-1. The predicted structure of Pgp-1 includes an NH2-terminal extracellular domain (residues 14-265), a transmembrane domain (residues 266-286), and a cytoplasmic tail (residues 287-358). Portions of the mouse Pgp-1 sequence are highly similar to that of the human CD44 cell surface glycoprotein implicated in cell adhesion. The protein also shows sequence similarity to the proteoglycan tandem repeat sequences found in cartilage link protein and cartilage proteoglycan core protein which are thought to be involved in binding to hyaluronic acid.

Extraction and characterization of a cytochemically assayable Na+/K+-ATPase inhibitor/glucose-6-phosphate dehydrogenase stimulator in the hypothalamus and plasma of man and the rat

Some physicochemical properties of partially purified hypothalamic material from the spontaneously hypertensive rat, and of plasma from man and the rat, have been characterized using a validated cytochemical bioassay which measures the ability of biological fluids to stimulate fresh guinea-pig kidney glucose-6-phosphate dehydrogenase (G6PD) after 2 min of exposure to the test substance, as an indication of their ability to inhibit Na+/K+ adenosine triphosphatase (Na+/K+-ATPase) after 4-6 min of exposure. The G6PD-stimulating activity of both hypothalamic extract and plasma is soluble in water and insoluble in chloroform. During electrophoresis the activity from both sites appears in the same fractions and travels considerably further than lysine. After high-pressure liquid chromatography the activity of hypothalamic extract appears in a discreet fraction which does not absorb u.v. light. The activity of both the hypothalamic extract and plasma survives boiling and acid hydrolysis, but is substantially inhibited by prior incubation with digoxin antibody. From ultrafiltration studies, the substance responsible for the ability to stimulate G6PD appears to have a molecular weight of less than 500. The G6PD-stimulating activity of hypothalamic extracts was destroyed by ashing and by base hydrolysis. The ability of plasma of high activity to stimulate G6PD is considerably increased by incubating at 37 degrees C for 15 min and destroyed by incubation for 45 min. It is concluded that these and several other previously noted similarities suggest that the cytochemically assayable Na+/K+-ATPase-inhibiting/G6PD-stimulating activity in the plasma and hypothalamus may be due to the same ouabain-like substance.

Na-K-ATPase-inhibiting and glucose-6-phosphate dehydrogenase-stimulating activity of plasma and hypothalamus of the Okamoto spontaneously hypertensive rat

The plasma of normal man and the rat, and an acetone extract of hypothalamus from the rat, have an ability to inhibit Na-K-ATPase which is related directly to salt intake. The ability of the plasma to inhibit Na-K-ATPase is raised in essential hypertension. The ability of plasma and of an acetone extract of hypothalamus from six spontaneously hypertensive (SHR) rats and six normotensive control (WKY) rats to inhibit Na-K-ATPase of fresh guinea-pig kidney was studied using cytochemical bioassay techniques. With a validated assay, which measures the capacity of biological samples to stimulate glucose-6-phosphate dehydrogenase (G6PD) as an index of their capacity to inhibit Na-K-ATPase, the mean G6PD-stimulating ability of the plasma from the SHR and the WKY rat was 772.3 +/- 48.1 units/ml and 12.5 +/- 2.6 units/ml respectively (P less than 0.01) and of the hypothalamic extracts it was 2.2 +/- 1.7 X 10(8) and 4.5 +/- 1.8 X 10(4) units/hypothalamus (P less than 0.01). With a semi-quantitative cytochemical assay, which measures Na-K-ATPase activity directly, plasma and an acetone extract of hypothalamus from the spontaneously hypertensive rat had much greater capacities to inhibit Na-K-ATPase than plasma and extract from the WKY rat. These raised levels of Na-K-ATPase inhibitory activity in the plasma of the SHR rat are similar to the highest values found in the plasma of patients with essential hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

Investigation of hirsutism: testosterone is not enough

In a consecutive series of 41 hirsute women clinically classified as benign androgen excess, only 34% were found to have elevated plasma 'total' testosterone (T), 22% having subnormal sex hormone binding globulin (SHBG). When expressed as the ratio T/SHBG ('free androgen index'), 85% of the patients had values above the normal range. It is concluded that this index is more reliable than total testosterone in assessing androgen status in female patients.