Determinants of DNA sequence specificity of the androgen, progesterone, and glucocorticoid receptors: evidence for differential steroid receptor response elements.

While androgen, progesterone, and glucocorticoid receptors perform distinct physiological functions by regulating unique sets of genes, in vitro they can transactivate a common high-affinity DNA-binding target. Naturally occurring steroid response elements display nucleotide divergence that lowers binding affinity in comparison to the optimal binding element, but enhances receptor-type specificity. We investigated the role of nucleotide deviations within the DNA-binding site for contribution to steroid receptor specificity. We hypothesized that receptor specificity drives the evolution of binding site sequence, rather than strictly receptor-binding affinity. Receptor-selective targets can evolve by some nucleotides selected on the basis of additional bond energy, and others may be selected by differential tolerance to discourage binding from inappropriate receptors. To identify receptor-specific binding sites, we mimicked these dual selection pressures in a receptor-competitive environment in which DNA binding sites for the androgen or progesterone receptors were selected in the presence of the glucocorticoid receptor. These analyses also demonstrated that steroid receptors strongly select nucleotides in the spacer and flanking regions of the half-site and do so in an asymmetric fashion, indicating that steroid receptors interact with DNA in an allosteric manner that affects the transcriptional activation potential.

Identification of rubella virus T-cell epitopes recognized in anamnestic response to RA27/3 vaccine: associations with boost in neutralizing antibody titer.

Rubella virus (RV)-specific cell-mediated immunity (CMI) and antibodies were measured in healthy adolescents reimmunized with measles-mumps-rubella (MMR) vaccine. Lymphocyte proliferation to RV synthetic peptides was determined before and at 2, 4 and 10 weeks after, MMR. After MMR, increased CMI was observed with 16 peptides, including six containing antibody neutralization (NT) domains. Positive CMI (stimulation index > or =2.0) to E1(254-285) and C(1-29) before vaccination was significantly associated with a boost in NT titers, while positive CMI at weeks 2 or 4 to E1(254-285), E1(301-314), E1(389-408), E1(462-481), E2(134-150), E2(140-156), E2(168-179), C(1-29) and C(88-111) showed the same association.

Early diet influences hepatic hydroxymethyl glutaryl coenzyme A reductase and 7alpha-hydroxylase mRNA but not low-density lipoprotein receptor mRNA during development.

Plasma cholesterol levels increase after birth, and to a greater extent in breast-fed versus formula-fed infants. This increase is believed to be due to the high fat and cholesterol content of the infant diet, but little is known about the effects of early diet on the expression of proteins involved in regulating cholesterol metabolism. This study examined changes in the expression of hepatic proteins regulating cholesterol metabolism during development. Newborn piglets were fed sow milk or one of four formulas for 18 days. The formulas had similar levels of palmitic acid (16:0) as in milk, supplied as palm olein oil with 16:0 esterified predominantly to the sn-1,3 position or as synthesized triglyceride (TG) with 16:0 esterified mainly to the sn-2 position of glycerol, each with no cholesterol (<0.10 mmol/L) or 0.65 mmol/L cholesterol added. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of mRNA levels was used to assess the effects of diet on hepatic hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase, low-density lipoprotein (LDL) receptor, and 7alpha-hydroxylase (C7H). LDL receptor mRNA levels showed no appreciable difference between milk- and formula-fed piglets. However, the levels of HMG-CoA reductase and C7H mRNA were higher (P < .05) in all formula-fed versus milk-fed piglets, irrespective of the formula TG source or cholesterol content. The lower levels of HMG-CoA reductase and C7H mRNA in milk-fed piglets were accompanied by higher (P < .05) plasma total, high-density lipoprotein (HDL), and apolipoprotein (apo) B-containing cholesterol. These studies show that the levels of hepatic HMG-CoA reductase and C7H mRNA, but probably not LDL receptor mRNA, are altered by early diet.

Chronic rubella vaccine-associated arthropathy.

Rubella immunization or infection is an uncommonly recognized cause of acute, recurrent, or persistent musculoskeletal manifestations. After routine rubella immunization, two women presented with the onset of polyarthralgia, arthritis, maculopapular rash, fever, paresthesia, and malaise with persistent or recurrent manifestations lasting longer than 24 months after vaccination. The patients expressed rubella virus RNA in peripheral-blood leukocytes 10 and 8 months after vaccination, respectively, in contrast to repeated negative results in asymptomatic rubella-immunized controls. One patient developed significantly depressed antibody responses to rubella virus after vaccination and experienced a prolonged clinical improvement after a 3-month course of intravenous immune globulin. The second patient had normal antibody responses to rubella virus and underwent no clinical improvement during or after intravenous immune globulin therapy. Rubella immunization or infection should be considered as additional causative factors in evaluation of acute and continuing musculoskeletal syndromes.

Cellular hyperimmunoreactivity to rubella virus synthetic peptides in chronic rubella associated arthritis.

OBJECTIVES: Immune recognition of the major structural proteins of rubella virus by peripheral blood mononuclear cells and synovial inflammatory infiltrates of a patient with documented chronic rubella associated arthritis was compared with responses of normal healthy rubella virus immunoreactive subjects to establish if there were unusual response patterns associated with rubella associated arthritis in this subject. METHODS: Synthetic peptides (16-33 amino acids in length) representing selected amino acid sequences of the rubella virus envelope (E1 and E2) and capsid (C) proteins were used in lymphocyte stimulation assays with peripheral blood mononuclear cells or synovial inflammatory infiltrates to determine T lymphocyte recognition of antigenic sites within the synthetic peptides. A rubella virus specific polymerase chain reaction was used to determine the persistence of rubella virus in the patient's cells. RESULTS: The patient's peripheral blood mononuclear cells showed abnormally increased lymphoproliferative responses to three E1 synthetic peptides encompassing residues 219-234, 389-411, and 462-481, and one E2 synthetic peptide containing the sequence 50-72, of which the last three were predicted to contain T cell antigenic sites. Although the patient's peripheral blood mononuclear cells showed positive proliferative responses to C synthetic peptides, these were not unusual. The number of synthetic peptides within the E1, E2, and C panels recognised by the patient's peripheral blood mononuclear cells was greater than was previously observed in normal healthy subjects. The recognition of synthetic peptides by synovial inflammatory infiltrates was similar to peripheral blood mononuclear cells but the responses measured were lower. The polymerase chain reaction was negative for rubella virus detection in peripheral blood mononuclear cells and synovial inflammatory infiltrates. CONCLUSIONS: Abnormally increased T cell recognition of antigenic sites within rubella virus E1 and E2 proteins observed in this patient with rubella associated arthritis suggests chronic antigenaemia due to persistent rubella virus in tissue sites other than peripheral blood mononuclear cells or synovial inflammatory infiltrates.

pH-dependent solubility shift of rubella virus capsid protein.

The mechanism of capsid uncoating in rubella virus and other togaviridae is not well understood. This study presents data which suggest that rubella virus capsid undergoes a structural change from having hydrophilic to hydrophobic properties, between pH 5 and 5.5. Such a conformational change would allow capsid uncoating to occur within the lysosome, allowing RNA penetration to occur upon fusion of the viral envelope with the limiting membrane of the lysosome.

Translocation of rubella virus glycoprotein E1 into the endoplasmic reticulum.

Rubella virus (RV) contains four structural proteins, C (capsid), E2a, E2b, and E1, which are derived from posttranslational processing of a single polyprotein precursor, p110. C protein is nonglycosylated and is thought to interact with RV RNA to form a nucleocapsid. E1 and E2 are membrane glycoproteins that form the spike complexes located on the virion exterior. Two different E1 cDNAs were used to analyze the requirements for translocation of E1 into the endoplasmic reticulum. Analysis of expression of these cDNAs both in vivo and in vitro showed that RV E1 was stably expressed and glycosylated in COS cells and correctly targeted into microsomes in the absence of E2 glycoprotein. The results provide experimental evidence that translocation of RV E1 glycoprotein into the endoplasmic reticulum is mediated by a signal peptide contained within the 69 carboxyl-terminal residues of E2.

A grandpaternally derived de novo deletion within Xp21 initially presenting in carrier females diagnosed as Kugelberg-Welander syndrome.

We report on two sisters with a history of muscle weakness and an electromyogram (EMG) diagnosis of Kugelberg-Welander syndrome (KWS) or juvenile spinal muscular atrophy. A half-brother to these women was diagnosed to have Duchenne muscular dystrophy (DMD). Using molecular probes, we identified a deletion within Xp21 in this isolated case of DMD. Sequences detected by pXJ1.1 are deleted, while fragments detected by pERT87 are intact. Both of these probes are derived from the DMD locus. We have shown that the affected sisters share with their half-brother DNA markers that are linked to the DMD gene and inherited from their maternal grandfather. Dosage analysis of Southern blots show monosomy for pXJ1.1, which has allowed us to determine carrier status within this family and to show that the half-sisters are manifesting DMD carriers.

Prenatal diagnosis in Becker muscular dystrophy.

Prenatal diagnosis in a pregnancy at risk for Becker muscular dystrophy is reported. The diagnosis was made prior to 12 weeks of gestation by typing a CVS sample for DNA markers.

Isolation and characterization of DNA probes from a flow-sorted human chromosome 8 library that detect restriction fragment length polymorphism (RFLP).

We have used a recombinant DNA library constructed from flow-sorted human chromosome 8 as a source of single-copy human probes. These probes have been screened for restriction fragment length polymorphism (RFLP) by hybridization to Southern transfers of genomic DNA from five unrelated individuals. We have detected six RFLPs distributed among four probes after screening 741 base pairs for restriction site variation. These RFLPs all behave as codominant Mendelian alleles. Two of the probes detect rare variants, while the other two detect RFLPs with PIC values of .36 and .16. Informative probes will be useful for the construction of a linkage map for chromosome 8 and for the localization of mutant alleles to this chromosome.