An Upsurge of Measles Cases in Mali-a Consequence of Pandemic-associated Disruption in Routine Immunization.

Measles deaths highlight immunization program gaps. In the Child Health and Mortality Prevention Surveillance study in Mali, we observed a rise in under-5 measles-related deaths in 2022 that corresponded with increased measles cases at the same time and a decline in measles vaccine coverage in Mali in 2020.

Regulatory haplotypes in ARG1 are associated with altered bronchodilator response.

RATIONALE: ß2-agonists, the most common treatment for asthma, have a wide interindividual variability in response, which is partially attributed to genetic factors. We previously identified single nucleotide polymorphisms in the arginase 1 (ARG1) gene, which are associated with ß2-agonist bronchodilator response (BDR). OBJECTIVES: To identify cis-acting haplotypes in the ARG1 locus that are associated with BDR in patients with asthma and regulate gene expression in vitro. METHODS: We resequenced ARG1 in 96 individuals and identified three common, 5' haplotypes (denoted 1, 2, and 3). A haplotype-based association analysis of BDR was performed in three independent, adult asthma drug trial populations. Next, each haplotype was cloned into vectors containing a luciferase reporter gene and transfected into human airway epithelial cells (BEAS-2B) to ascertain its effect on gene expression. MEASUREMENTS AND MAIN RESULTS: BDR varied by haplotype in each of the three populations with asthma. Individuals with haplotype 1 were more likely to have higher BDR, compared to those with haplotypes 2 and 3, which is supported by odds ratios of 1.25 (95% confidence interval, 1.03-1.71) and 2.18 (95% confidence interval, 1.34-2.52), respectively. Luciferase expression was 50% greater in cells transfected with haplotype 1 compared to haplotypes 2 and 3. CONCLUSIONS: The identified ARG1 haplotypes seem to alter BDR and differentially regulate gene expression with a concordance of decreased BDR and reporter activity from haplotypes 2 and 3. These findings may facilitate pharmacogenetic tests to predict individuals who may benefit from other therapeutic agents in addition to ß(2)-agonists for optimal asthma management. Clinical trial registered with www.clinicaltrials.gov (NCT00156819, NCT00046644, and NCT00073840).

Differential coupling of Arg- and Gly389 polymorphic forms of the beta1-adrenergic receptor leads to pathogenic cardiac gene regulatory programs.

The beta(1)-adrenergic receptor (beta(1)AR; ADRB1) polymorphism Arg389Gly is located in an intracellular loop and is associated with distinct human and mouse cardiovascular phenotypes. To test the hypothesis that beta(1)-Arg389 and beta(1)-Gly389 alleles could differentially couple to pathways beyond that of classic G(s)-adenylyl cyclase (AC)/cAMP signaling, we performed comparative gene expression profile analyses on hearts from wild-type and transgenic mice that expressed either human beta(1)-Arg389 or beta(1)-Gly389 receptors, or AC5, sampling at an early age prior to the onset of pathological features. All three models upregulated the expression of genes associated with RNA metabolism and translation and downregulated genes associated with mitochondria and energy metabolism, consistent with shared cAMP-driven increase in cardiac contractility, protein synthesis, and compensatory downregulation of mitochondrial energy production. Both beta(1)AR alleles activated additional genes associated with other pathways. Uniquely, beta(1)-Arg389 hearts exhibited upregulated expression of genes associated with inflammation, programmed cell death, and extracellular matrix. These observations expand the scope of 7-transmembrane domain receptor signaling propagation beyond known cognate G protein couplings. Moreover, they implicate alterations of a repertoire of processes evoked by a single amino acid variation in the cardiac beta(1)AR that might be exploited for genotype-specific heart failure diagnostics and therapeutics.

Bitransgenesis with beta(2)-adrenergic receptors or adenylyl cyclase fails to improve beta(1)-adrenergic receptor cardiomyopathy.

Cardiomyopathic effects of beta-adrenergic receptor (betaAR) signaling are primarily due to the beta(1)AR subtype. beta(1)/beta(2)AR and beta(1)/adenylyl cyclase type 5 (AC5) bitransgenic mice were created to test the hypothesis that beta(2)AR or AC5 co-overexpression has beneficial effects in beta(1)AR-mediated cardiomyopathy. In young mice, beta(1)/beta(2) hearts had a greater increase in basal and isoproterenol-stimulated contractility compared to beta(1)/AC5 and beta(1)AR hearts. By 6 months, beta(1)AR and beta(1)/beta(2) hearts retained elevated basal contractility but were unresponsive to agonist. In contrast, beta(1)/AC5 hearts maintained a small degree of agonist responsiveness, which may be due to a lack of beta(1)AR downregulation that was noted in beta(1)- and beta(1)/beta(2) hearts. However, by 9 -months, beta(1), beta(1)/beta(2), and beta(1)/AC5 mice had all developed severely depressed fractional shortening in vivo and little response to agonist. p38 mitogen activated protein kinase (MAPK) was minimally activated by beta(1)AR, but was markedly enhanced in the bitransgenics. Akt activation was only found with the bitransgenics. The small increase in cystosolic second mitochondria-derived activator of caspase (Smac), indicative of apoptosis in 9-month beta(1)AR hearts, was suppressed in beta(1)/AC5, but not in beta(1)/beta(2), hearts. Taken together, the unique signaling effects of enhanced beta(2)AR and AC5, which have the potential to afford benefit in heart failure, failed to salvage ventricular function in beta(1)AR-mediated cardiomyopathy.

Bcl-x(L) sequesters its C-terminal membrane anchor in soluble, cytosolic homodimers.

Bcl-x(L) is a potent inhibitor of apoptosis. While Bcl-x(L) can be bound to mitochondria, a substantial fraction, depending on the cell type or tissue, is found in the cytosol of healthy cells. Gel filtration and crosslinking experiments reveal that, unlike monomeric Bax, Bcl-x(L) migrates in a complex of approximately 50 kDa in the cytosol. Co-immunoprecipitation experiments indicate that Bcl-x(L) in the cytosol forms homodimers. The C-terminal hydrophobic tails of two Bcl-x(L) molecules are involved in homodimer formation, and analysis of mutants demonstrates that the C-terminal lysine residue and the G138 residue lining the BH3-binding pocket are required for homodimerization. The flexible loop preceding the C-terminal tail in Bcl-x(L) is longer than that of several monomeric Bcl-2 family members and is a requisite for the homodimer formation. Bad binding to Bcl-x(L) dissociates the homodimers and triggers Bcl-x(L) binding to mitochondrial membranes. The C-terminal tail of Bcl-x(L) is also required to mediate Bcl-x(L)/Bax heterodimer formation. Both mitochondrial import and antiapoptotic activity of different Bcl-x(L) mutants correlate with their ability to form homodimers.

Mitochondrial release of AIF and EndoG requires caspase activation downstream of Bax/Bak-mediated permeabilization.

Mitochondrial outer-membrane permeabilization by pro-apoptotic Bcl-2 family members plays a crucial role in apoptosis induction. However, whether this directly causes the release of the different mitochondrial apoptogenic factors simultaneously is currently unknown. Here we report that in cells or with isolated mitochondria, pro-apoptotic Bcl-2 proteins cause the release of cytochrome c, Smac/Diablo and HtrA2/Omi but not endonuclease G (EndoG) and apoptosis-inducing factor (AIF). In cells treated with Bax/Bak-dependent pro-apoptotic drugs, neither the caspase inhibitor zVAD-fmk nor loss of Apaf-1 affected the efflux of cytochrome c, Smac/Diablo and HtrA2/Omi, but both prevented the release of EndoG and AIF. Our findings identify the mitochondrial response to pro-apoptotic stimuli as a selective process leading to a hierarchical ordering of the effectors involved in cell death induction. Moreover, as in Caenorhabditis elegans, EndoG and AIF act downstream of caspase activation. Thus EndoG and AIF seem to define a 'caspase-dependent' mitochondria-initiated apoptotic DNA degradation pathway that is conserved between mammals and nematodes.

Mitofusin-1 protein is a generally expressed mediator of mitochondrial fusion in mammalian cells.

Mitochondrial fusion may regulate mitochondrial morphogenesis and underlie complementation between mitochondrial genomes in mammalian cells. The nuclear encoded mitochondrial proteins Mfn1 and Mfn2 are human homologues of the only known protein mediators of mitochondrial fusion, the Drosophila Fzo GTPase and Saccharomyces cerevisiae yFzo1p. Although the Mfn1 and Mfn2 genes were broadly expressed, the two genes showed different levels of mRNA expression in different tissues. Two Mfn1 transcripts were detected at similar levels in a variety of human tissues and were dramatically elevated in heart, while Mfn2 mRNA was abundantly expressed in heart and muscle tissue but present only at low levels in many other tissues. Human Mfn1 protein localized to mitochondria and participated in a high molecular weight, detergent extractable protein complex. Forced expression of Mfn1 in cultured cells caused formation of characteristic networks of mitochondria. Introduction of a point mutation in the conserved G1 region of the predicted GTPase domain (Mfn1K88T) dramatically decreased formation of mitochondrial networks upon Mfn1 overexpression, suggesting that network formation required completion of the Mfn1 GTPase cycle. Conversely, a protein variant carrying a point mutation in the G2 motif of the Mfn1 GTPase domain acted as a dominant negative: overexpression of Mfn1T109A resulted in fragmentation of mitochondria. We propose that Mfn1T109A interferes with fusion activity of endogenous Mfn1 protein, possibly by binding necessary cofactors, so to allow unopposed mitochondrial fission. Thus, Mfn1 appears to be a key player in mediating mitochondrial fusion and morphology in mammalian cells.

Spatial and temporal association of Bax with mitochondrial fission sites, Drp1, and Mfn2 during apoptosis.

We find that Bax, a proapoptotic member of the Bcl-2 family, translocates to discrete foci on mitochondria during the initial stages of apoptosis, which subsequently become mitochondrial scission sites. A dominant negative mutant of Drp1, Drp1K38A, inhibits apoptotic scission of mitochondria, but does not inhibit Bax translocation or coalescence into foci. However, Drp1K38A causes the accumulation of mitochondrial fission intermediates that are associated with clusters of Bax. Surprisingly, Drp1 and Mfn2, but not other proteins implicated in the regulation of mitochondrial morphology, colocalize with Bax in these foci. We suggest that Bax participates in apoptotic fragmentation of mitochondria.