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Enlargement of high density lipoprotein in mice via liver X receptor activation requires apolipoprotein E and is abolished by cholesteryl ester transfer protein expression.

The factors involved in the generation of larger high density lipoprotein (HDL) particles, HDL1 and HDLc, are still not well understood. Administration of a specific synthetic liver X receptor (LXR) agonist, T0901317, in mice resulted in an increase of not only HDL cholesterol but also HDL particle size (Cao, G., Beyer, T. P., Yang, X. P., Schmidt, R. J., Zhang, Y., Bensch, W. R., Kauffman, R. F., Gao, H., Ryan, T. P., Liang, Y., Eacho, P. I., and Jiang, X. C. (2002) J. Biol. Chem. 277, 39561-39565). We have investigated the roles that apoE and CETP may play in this process. We treated apoE-deficient, cholesterol ester transport protein (CETP) transgenic, and wild type mice with various doses of the LXR agonist and monitored their HDL levels. Fast protein liquid chromatography and apolipoprotein analysis revealed that in apoE knockout mouse plasma, there was neither induction of larger HDL formation nor increase of HDL cholesterol, suggesting that apoE is essential for the LXR agonist effects on HDL metabolism. In CETP transgenic mice, CETP expression completely abolished LXR agonist-mediated HDL enlargement and greatly attenuated HDL cholesterol levels. Analysis of HDL particles by electron microscope and nondenaturing gel electrophoresis revealed similar findings. In apoE-deficient mice, LXR agonist also produced a significant increase in very low density lipoprotein/low density lipoprotein cholesterol and apolipoprotein B content. Our studies provide direct evidence that apoE and CETP are intimately involved in the accumulation of the enlarged HDL (HDL1 or HDLc) particles in mice.

Animals↗

Loss of tolerance associated with disappearance of B cells in a patient sequentially transplanted with paternal and maternal bone marrow for the treatment of severe combined immunodeficiency disease.

We have studied the tolerance of engrafted T cells from a severe combined immunodeficiency disease patient sequentially transplanted with T-cell-depleted bone marrow from both HLA haploidentical parents. The T cells from this patient were shown by HLA typing and cytogenetic analysis to be of material origin (donor of the second graft) while HLA typing of peripheral E--populations and of an Epstein-Barr virus-transformed B-cell line established 2 1/2 years after transplantation revealed the presence of host, maternal, and paternal (donor of the first graft) HLA antigens. When tested at 30 and 60 months after the last transplant, engrafted T cells from this patient had only weak mixed lymphocyte culture reactivity to paternal cells which could be inhibited by monoclonal antibodies to HLA-DQ and DR but not by anti-DP. T cells obtained 60 months after transplant were stimulated with paternal cells in both bulk and limiting dilution cultures and failed to generate typical allocytotoxic cells to paternal T- or B-cell targets. Mixed lymphocyte cultures performed at 71 months revealed an increased proliferative response by patient cells to paternal antigens; however, the engrafted T cells remained tolerant to maternal and host antigens. Limiting dilution analysis performed at this time revealed the presence of cytolytic cells directed to paternal antigens. There were no detectable B cells (only identified source of paternal antigen) as measured by immunofluorescent analysis of peripheral blood, nor any evidence of B-cell function as assessed by in vitro assays (proliferation to staphylococcus aureus Cowen strain A and mitogen-stimulated immunoglobulin production) or in vivo production of serum immunoglobulin at 60 and 71 months. The appearance of alloreactivity associated with the loss of B cells in this patient further supports the conclusion that the maintenance of tolerance to major histocompatibility complex disparate cells requires the continued in vivo presence of cells bearing the tolerizing antigens.

Antibody Formation↗

Normal hypermutation in antibody genes from congenic mice defective for DNA polymerase iota.

Several low fidelity DNA polymerases participate in generating mutations in immunoglobulin genes. Polymerase eta is clearly involved in the process by causing substitutions of A:T base pairs, whereas polymerase iota has a controversial role. Although the frequency of mutations was decreased in the BL2 cell line deficient for polymerase iota, hypermutation was normal in the 129 strain of mice, which has a natural nonsense mutation in the Poli gene. It is possible that the mice compensated for the defect over time, or that polymerase eta substituted in the absence of polymerase iota. To examine polymerase iota in a genetically defined background, we backcrossed the 129 nonsense mutation to the C57BL/6 strain for six generations. Class switch recombination and hypermutation were studied in these mice and in congenic mice doubly deficient for both polymerases iota and eta. The absence of both polymerases did not affect production of IgG1, indicating that these enzymes are not involved in switch recombination. Poli(-/-F6) mice had the same types of nucleotide substitutions in variable genes as their C57BL/6 counterparts, and mice doubly deficient for polymerases iota and eta had the same mutational spectrum as Polh-/- mice. Thus, polymerase iota did not contribute to the mutational spectra, even in the absence of polymerase eta.

Animals↗

Management of hereditary angioedema: a Canadian approach.

C1 esterase inhibitor (C1-INH) deficiency is a rare disorder that lacks consensus for diagnosis therapy and management. Recognizing that Canada is behind the European approach to this disorder, we have formed the Canadian Hereditary Angioedema Society (CHAES)/Société d'angioédème héréditaire du Canada (SAHC) to foster knowledge of this disorder in Canada and to advance care of patients with this disorder in Canada. We here present a review of treatment of this disorder in Canada including prevention of angioedema events and use of replacement therapy and present an algorithm for diagnosis therapy and management of C1-INH deficiency in Canada for discussion at our International Conference on Hereditary Angioedema to be held in Toronto, Canada, October 24th to 26th, 2003.

Algorithms↗

Charting host structural variations in cervical cancer by long-read sequencing pinpoints a functional deletion in PIAS1.

Host structural variations (SVs) are critical in cancer development but their landscape and interaction with HPV integration in cervical carcinogenesis remain unclear. In this study, we performed Nanopore long-read sequencing on five HPV-positive cervical cancer tissues and two cell lines to profile host SVs. We identified thousands of SVs and statistically demonstrated their significant enrichment in genomic windows ±25 to ±50 kb from HPV integration sites. Cross-sample analysis revealed 60 shared SVs, including a recurrent deletion within the PIAS1 gene. Multi-omics integration (Hi-C, H3K27ac ChIP-seq, and TCGA data) showed that this deletion is associated with reduced PIAS1 expression, disruption of local topologically associating domains, advanced pathological tumor stage, and poorer overall survival. Functional assays confirmed that PIAS1 deficiency inhibits cervical cancer cell proliferation and migration. Our findings identify a PIAS1 deletion as a candidate driver event, and underscore the pivotal role of host genomic instability in HPV-associated oncogenesis.

Cervical cancer↗

Genomic structure and expression of the mouse ESET gene encoding an ERG-associated histone methyltransferase with a SET domain.

ESET (ERG-associated protein with a SET domain, also called SETDB1) is a novel histone methyltransferase that catalyzes methylation of histone H3-lysine 9 (H3-K9). Here we describe the genomic structure and expression of the mouse ESET gene that gives rise to ESET protein and its alternative splicing product. ESET is a 36-kb single copy gene and full-length ESET transcript consisting of 22 exons. The splicing variant retains only the first 12 exons and thus lacks sequences encoding the methyl CpG-binding domain and the catalytic SET domain. The U2 type conserved GT/AG consensus sequence is present at all of the splicing junctions within the ESET gene. The transcription initiation site of the ESET gene was determined by 5'-RACE experiment and by primer extension. The 5'-flanking sequence of the ESET gene does not contain the consensus TATA box. Instead, this ESET promoter region has features such as SP1-binding sites that are typical of housekeeping genes. The ESET promoter was functionally active when tested in transfection and luciferase assay. Full-length ESET transcript appears to be ubiquitously expressed. While the SET domain-deficient splicing variant is present in immortalized cell lines, it is undetectable by RT-PCR in the majority of normal mouse tissues.

Alternative Splicing↗

SEK1/MKK4 is required for maintenance of a normal peripheral lymphoid compartment but not for lymphocyte development.

SAPK is a member of the group of evolutionary conserved stress-activated kinases that mediate control of cellular death and proliferation. In lymphocytes, the SAPK pathway has been implicated in signaling from antigen, costimulatory, and death receptors; SEK1, which directly activates SAPK, is required for early embryonic development and has also been reported to be essential for normal lymphocyte development. In contrast to the latter findings, we have used RAG-2-deficient blastocyst complementation to show that SEK1-deficient embryonic stem cells support unimpaired T and B lymphocyte development. Moreover, mature SEK1-deficient lymphocytes are capable of SAPK activation. Surprisingly, however, aging SEK1-deficient chimeric mice frequently develop lymphadenopathy and polyclonal B and T cell expansions. Thus, SEK1 is not required for lymphocyte development, but is required for maintaining peripheral lymphoid homeostasis.

Animals↗

The future of plasma-derived clotting factor concentrates.

In developed countries, preferred treatments for both haemophilia A and B have moved toward recombinant clotting factor concentrates, while plasma-derived replacement therapies are still required by many patients. Great improvements have been made in producing relatively pathogen-free clotting factor replacements from pooled plasma. The fluidity and complexity of the worldwide plasma product market are discussed in the context of the 'yin and yang' of plasma therapeutics, showing how multiple issues can influence the safety and availability of clotting factor concentrates. Use of plasma-derived products will likely continue for the next decade for patients with inhibitors, patients with von Willebrand disease, those requiring bypassing agents, in immune tolerance induction, and for treatment of rare inherited deficiencies of procoagulant or anticoagulant proteins. Furthermore, in developing countries many of the most advanced therapies are not available for the majority of haemophilia patients, and thus plasma-derived replacement concentrates will continue to be used even for noninhibitor patients.

Blood Coagulation Factors↗

Heterogeneity of the human H blood group alpha(1,2)fucosyltransferase gene among para-Bombay individuals.

BACKGROUND AND OBJECTIVES: The para-Bombay phenotype has a relatively high frequency of about 1 in 8,000 Taiwanese. Studies were carried out on eight healthy and unrelated Taiwanese with the para-Bombay phenotype to cast light on its immunogenetic basis. MATERIALS AND METHODS: Blood and saliva samples were tested with standard hemagglutination techniques. Salivary ABH substances were determined by hemagglutination inhibition. PCR techniques were used to amplify the coding region of the H genes. RESULTS: Five different h alleles, designated as h1, h2, h3, h4 and h5, were identified in the Taiwanese with the para-Bombay phenotype. The h1 allele loses one of the three AG repeats located at the nucleotides 547-552 of the H gene, whereas two of the three T repeats located at the nucleotides 880-882 are deleted in the h2 allele. The h3 allele contains a C658 to T missense mutation, whereas two missense mutations, C35 to T and A980 to C were identified in the h4 allele. A T460 to C missense is present in the h5 allele. The h5 allele was identified in an individual whose red blood cells contain blood group A antigen but not H antigen, and thus may be considered a weak variant of the H gene. CONCLUSIONS: So far no biologic relevance of the H antigen has been discovered, and its deficiency does not seem to produce any deleterious effects. There may be better understanding of the evolutionary basis for the polymorphisms at these loci after systematic study of different ethnic populations.

ABO Blood-Group System↗

Murine leptin deficiency alters Kupffer cell production of cytokines that regulate the innate immune system.

BACKGROUND & AIMS: ob/ob mice are used to study the mechanisms that regulate the progression from steatosis to nonalcoholic steatohepatitis. The livers of ob/ob mice are depleted of CD4-positive natural killer cells, components of the innate immune system that induce anti-inflammatory cytokines. Although this may explain the sensitivity of fatty livers to lipopolysaccharide, why such hepatic CD4-positive natural killer cell depletion occurs is uncertain. Because leptin regulates macrophages, our hypothesis is that leptin deficiency alters Kupffer cell production of cytokines that inhibit (e.g., interleukin [IL]-12) or enhance (e.g., IL-15) hepatic CD4-positive natural killer cell viability. METHODS: Kupffer cell cytokine production and the hepatic content of CD4-positive natural killer cells were compared in ob/ob and lean mice. ob/ob mice were then treated with IL-15 or leptin to determine whether either factor improved their immunologic abnormalities. RESULTS: Compared with control Kupffer cells, ob/ob Kupffer cells produced less IL-15 basally and more IL-12 after lipopolysaccharide stimulation. Treatment of ob/ob mice with IL-15 for 1 week normalizes their hepatic CD4-positive natural killer cell content. Leptin increases the hepatic expression of IL-15 in ob/ob mice and partially replenishes their hepatic CD4-positive natural killer cells. CONCLUSIONS: Leptin deficiency increases hepatic IL-12 and reduces hepatic IL-15 expression. The abnormal production of these Kupffer cell factors promotes hepatic CD4-positive natural killer cell depletion in ob/ob livers.

Animals↗

Molecular cloning of the human gene, PNKP, encoding a polynucleotide kinase 3'-phosphatase and evidence for its role in repair of DNA strand breaks caused by oxidative damage.

Mammalian polynucleotide kinases catalyze the 5'-phosphorylation of nucleic acids and can have associated 3'-phosphatase activity, predictive of an important function in DNA repair following ionizing radiation or oxidative damage. The sequences of three tryptic peptides from a bovine 60-kDa polypeptide that correlated with 5'-DNA kinase and 3'-phosphatase activities identified human and murine dbEST clones. The 57.1-kDa conceptual translation product of this gene, polynucleotide kinase 3'-phosphatase (PNKP), contained a putative ATP binding site and a potential 3'-phosphatase domain with similarity to L-2-haloacid dehalogenases. BLAST searches identified possible homologs in Caenorhabditis elegans, Schizosaccharomyces pombe, and Drosophila melanogaster. The gene was localized to chromosome 19q13.3-13.4. Northern analysis indicated a 2-kilobase mRNA in eight human tissues. A glutathione S-transferase-PNKP fusion protein displayed 5'-DNA kinase and 3'-phosphatase activities. PNKP is the first gene for a DNA-specific kinase from any organism. PNKP expression partially rescued the sensitivity to oxidative damaging agents of the Escherichia coli DNA repair-deficient xth nfo double mutant. PNKP gene function restored termini suitable for DNA polymerase, consistent with in vivo removal of 3'-phosphate groups, facilitating DNA repair.

Amino Acid Sequence↗

Matricellular proteins as modulators of cell-matrix interactions: adhesive defect in thrombospondin 2-null fibroblasts is a consequence of increased levels of matrix metalloproteinase-2.

Thrombospondin 2 (TSP2)-null mice, generated by disruption of the Thbs2 gene, display a variety of connective tissue abnormalities, including fragile skin and the presence of abnormally large collagen fibrils with irregular contours in skin and tendon. In this study we demonstrate that TSP2-null skin fibroblasts show a defect in attachment to a number of matrix proteins, and a reduction in cell spreading. To investigate the molecular mechanisms responsible for these abnormal cell-matrix interactions, we compared the levels of matrix metalloproteinases (MMPs) in wild-type and mutant fibroblasts. Isolation and analysis of gelatinases from conditioned media by gelatin-agarose affinity chromatography and gelatinolytic assays demonstrated that TSP2-null fibroblasts produce a 2-fold increase in gelatinase A (MMP2) compared with wild-type cells. The adhesive defect was corrected by treatment of TSP2-null fibroblasts with soluble TSP2, with the MMP inhibitors BB94 and tissue inhibitor of metalloproteinase-2, and with a neutralizing antibody to MMP2. Moreover, stable transfection of TSP2-null fibroblasts with mouse TSP2 cDNA corrected both the adhesive defect and the altered expression of MMP2. Finally, MMP2 was shown to interact with TSP2 in a direct-binding plate assay. We conclude that TSP2 plays an important role in cell-matrix interactions, and that a deficiency in the protein results in increased levels of MMP2 that contribute to the adhesive defect in TSP2-null fibroblasts and could play a role in the complex phenotype of TSP2-null mice.

Animals↗

Deficiency of growth hormone receptor does not affect male reproduction in dwarf chickens.

Sex-linked dwarf chickens caused by the mutation of the growth hormone receptor gene are characterized by normal growth hormone (GH), very low insulin-like growth factor I (IGF-I) level in the blood, and reduced growth. It has been demonstrated that the sex-linked dwarfing gene has negative effects on female reproduction. In the current study, dwarf cocks and their phenotypic normal siblings were used to investigate the effects of dwarf gene on male reproduction. Dwarf cocks grew slower than the normal cocks did, and at 20 wk of age, their BW were 36.4% smaller. However, all parameters for semen quality, including volume, sperm concentration, viability, mobility, pH, and percentage of abnormal sperms, examined at 30 wk of age showed no significant difference between normal and dwarf cocks. The fertility of dwarf cocks was 95.2%, and the normal was 92.4%. The concentrations of GH and IGF-I in serum and seminal plasma were measured with RIA and ELISA, respectively. The serum GH in the dwarf cocks was significantly higher than their normal siblings (P < 0.05), whereas the serum IGF-I in the dwarf cocks was very low. However, the concentration of seminal IGF-I in dwarf cocks was similar to that of their normal siblings, indicating that IGF-I might be produced and acted independently in testis. In conclusion, the deficiency in GH receptor did not affect the male reproduction in dwarf chickens, and the fertility of dwarf cocks could be satisfactory for production when artificial insemination was adopted.

Animals↗

Auxin-induced ethylene production as related to auxin metabolism in leaf discs of tobacco and sugar beet.

Exogenously supplied indole-3-acetic acid (IAA) stimulated ethylene production in tobacco (Nicotiana glauca) leaf discs but not in those of sugar beet (Beta vulgaris L.). The stimulatory effect of IAA in tobacco was relatively small during the first 24 hours of incubation but became greater during the next 24 hours. It was found that leaf discs of these two species metabolized [1-(14)C]IAA quite differently. The rate of decarboxylation in sugar beet discs was much higher than in tobacco. The latter contained much less free IAA but a markedly higher level of IAA conjugates. The major conjugate in the sugar beet extracts was indole-3-acetylaspartic acid, whereas tobacco extracts contained mainly three polar IAA conjugates which were not found in the sugar beet extracts. The accumulation of the unidentified conjugates corresponded with the rise of ethylene production in the tobacco leaf discs. Reapplication of all the extracted IAA conjugates resulted in a great stimulation of ethylene production by tobacco leaf discs which was accompanied by decarboxylation of the IAA conjugates. The results suggest that in tobacco IAA-treated leaf discs the IAA conjugates could stimulate ethylene production by a slow release of free IAA. The inability of the exogenously supplied IAA to stimulate ethylene production in the sugar beet leaf discs was not due to a deficiency of free IAA within the tissue but rather to the lack of responsiveness of this tissue to IAA, probably because of an autoinhibitory mechanism existing in the sugar beet leaf discs.

Journal Article↗

Biallelic Variants in ATP1A4 Are Associated with Oligoasthenoteratozoospermia and Male Infertility.

Male infertility, often caused by structural and functional sperm defects, remains genetically unexplained in a substantial proportion of cases. ATP1A4 encodes a testis-specific isoform of the Na+, K+-ATPase, a membrane enzyme crucial for maintaining cellular ionic homeostasis. Previous studies on Atp1a4 knockout mice have demonstrated severe defects in sperm motility and flagellar architecture; however, the contribution of ATP1A4 variants to human male reproduction remains to be elucidated. In this study, we identified compound biallelic variants in ATP1A4, a missense variant (c.2578&#x2009;T>A, p.Tyr860Asn) and a frameshift variant (c.2582del, p.Gly861Aspfs*5), in a patient presenting with severe oligoasthenoteratozoospermia. Both variants markedly affected ATP1A4 protein expression. Morphological analyses revealed coiled and folded flagella, disrupted mitochondrial sheaths, and irregular head morphology in the patient's spermatozoa. Expression profiling revealed that ATP1A4 was highly enriched in post-meiotic spermatids and localized along the entire flagellum of mature sperm in both humans and mice, indicating a critical role in flagellar assembly and structural integrity. Notably, intracytoplasmic sperm injection (ICSI) in this patient resulted in low fertilization efficiency and failed implantation, suggesting a potential adverse impact of ATP1A4 deficiency on sperm functional competence beyond motility. These findings broaden the genetic spectrum of oligoasthenoteratozoospermia and highlight ATP1A4 as a potential gene associated with human male infertility.

Male↗

Poly(ADP-Ribose) polymerase promotes cardiac remodeling, contractile failure, and translocation of apoptosis-inducing factor in a murine experimental model of aortic banding and heart failure.

Oxidant stress-induced activation of poly(ADP-ribose) polymerase (PARP) plays a role in the pathogenesis of various cardiovascular diseases. We have now investigated the role of PARP in the process of cardiac remodeling and heart failure in a mouse model of heart failure induced by transverse aortic constriction (banding). The catalytic activity of PARP was inhibited by the potent isoindolinone-based PARP inhibitor INO-1001 or by PARP-1 genetic deficiency. PARP inhibition prevented the pressure overload-induced decrease in cardiac contractile function, despite the pressure gradient between both carotid arteries being comparable in the two experimental groups. The development of hypertrophy, the formation of collagen in the hearts, and the mitochondrial-to-nuclear translocation of the cell death factor apoptosis-inducing factor (AIF) were attenuated by PARP inhibition. The ability of the inhibitor to block the catalytic activity of PARP was confirmed by immunohistochemical detection of poly(ADP-ribose), the product of the enzyme in the heart. Plasma levels of INO-1001, as measured at the end of the experiments, were in the concentration range sufficient to block the oxidant-mediated activation of PARP in murine cardiac myocytes in vitro. Myocardial hypertrophy and AIF translocation was also reduced in PARP-1-deficient mice undergoing aortic banding, compared with their wild-type counterparts. Overall, the current results demonstrate the importance of poly(ADP-ribos)ylation in the pathogenesis of banding-induced heart failure.

Animals↗

Mature adipocytes and perivascular adipose tissue stimulate vascular smooth muscle cell proliferation: effects of aging and obesity.

Adipocytes and perivascular adipose tissue are emerging as regulators of vascular function. The effects of adipocytes and perivascular adipose tissue on human smooth muscle cell (SMC) proliferation were investigated. Conditioned medium was prepared from cultured premature and differentiated 3T3-L1 adipocytes and from periaortic adipose tissue from young (3 mo) and old (24 mo) Wistar-Kyoto (WKY) rats, lean and obese Zucker rats (3 mo), and WKY rats fed normal chow or a high-fat diet for 3 mo. Conditioned medium from differentiated (but not premature) adipocytes stimulated SMC proliferation, which was abolished by charcoal and proteinase K treatment but was resistant to heat, trypsin, or phospholipase B (to hydrolyze lysophosphatidic acid). Further experiments demonstrated that the growth factor(s) are hydrosoluble and present in the fraction of molecular mass >100 kDa. Moreover, conditioned medium from periaortic adipose tissue stimulated SMC proliferation, which was significantly enhanced in aged rats and in rats fed a high-fat diet but not in obese Zucker rats deficient in functional leptin receptors. In conclusion, mature adipocytes release hydrosoluble protein growth factor(s) with a molecular mass >100 kDa for SMCs. Perivascular adipose tissue stimulates SMC proliferation, which is enhanced in aged WKY and in high-fat, diet-induced obesity but not in leptin receptor-deficient obese Zucker rats. These adipocyte-derived growth factor(s) and the effect of perivascular adipose tissue may be involved in vascular disease associated with aging and obesity.

Adipocytes↗