617 research outputs found

    Apoptosis and Clearance of the Secretory Mammary Epithelium

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    Universities: The Fallen Angels of Bayh-Dole?

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    The Bayh-Dole Act of 1980 established a new default rule that allowed nonprofit organizations and small businesses to own, as a routine matter, patents on inventions resulting from research sponsored by the federal government. Although universities helped get the Bayh-Dole Act through Congress, the primary goal, as reflected in the recitals at the beginning of the new statute, was not to benefit universities but to promote the commercial development and utilization of federally funded inventions. In the years since the passage of the Bayh-Dole Act, universities seem to have lost sight of this distinction. Their behavior as patent seekers, patent enforcers, and patent policy stakeholders often seems to work against the commercialization goals of the Bayh-Dole Act and is difficult to explain or justify on any basis other than the pursuit of revenue

    The impact of Autism Spectrum Disorder and alexithymia on judgments of moral acceptability

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    One’s own emotional response toward a hypothetical action can influence judgments of its moral acceptability. Some individuals with autism spectrum disorder (ASD) exhibit atypical emotional processing, and moral judgments. Research suggests, however, that emotional deficits in ASD are due to co-occurring alexithymia, meaning atypical moral judgments in ASD may be due to alexithymia also. Individuals with and without ASD (matched for alexithymia) judged the moral acceptability of emotion-evoking statements and identified the emotion evoked. Moral acceptability judgments were predicted by alexithymia. Crucially, however, this relationship held only for individuals without ASD. While ASD diagnostic status did not directly predict either judgment, those with ASD did not base their moral acceptability judgments on emotional information. Findings are consistent with evidence demonstrating that decision-making is less subject to emotional biases in those with ASD

    Epithelial cell-directed efferocytosis in the post-partum mammary gland is necessary for tissue homeostasis and future lactation

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    <p>Abstract</p> <p>Background</p> <p>Mammary glands harbor a profound burden of apoptotic cells (ACs) during post-lactational involution, but little is known regarding mechanisms by which ACs are cleared from the mammary gland, or consequences if this process is interrupted. We investigated AC clearance, also termed efferocytosis, during post-lactational remodeling, using mice deficient for MerTK, Axl, and Tyro3, three related receptor tyrosine kinases (RTKs) regulating macrophage-mediated efferocytosis in monocytes. MerTK expression, apoptosis and the accumulation of apoptotic debris were examined in histological sections of MerTK-deficient, Axl/Tyro3-deficient, and wild-type mammary glands harvested at specific time points during lactation and synchronized involution. The ability of primary mammary epithelial cells (MECs) to engulf ACs was assessed in culture. Transplant of MerTK-deficient mammary epithelium into cleared WT mammary fat pads was used to assess the contribution of WT mammary macrophages to post-lactational efferocytosis.</p> <p>Results</p> <p>ACs induced MerTK expression in MECs, resulting in elevated MerTK levels at the earliest stages of involution. Loss of MerTK resulted in AC accumulation in post-lactational MerTK-deficient mammary glands, but not in Axl and Tyro3-deficient mammary glands. Increased vascularization, fibrosis, and epithelial hyperproliferation were observed in MerTK-deficient mammary glands through at least 60 days post-weaning, due to failed efferocytosis after lactation, but did not manifest in nulliparous mice. WT host-derived macrophages failed to rescue efferocytosis in transplanted MerTK-deficient mammary epithelium.</p> <p>Conclusion</p> <p>Efferocytosis by MECs through MerTK is crucial for mammary gland homeostasis and function during the post-lactational period. Efferocytosis by MECs thus limits pathologic consequences associated with the apoptotic load following lactation.</p

    ErbB4/HER4: Role in Mammary Gland Development, Differentiation and Growth Inhibition

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    The ErbB receptor tyrosine kinase family has often been associated with increased growth of breast epithelial cells, as well as malignant transformation and progression. In contrast, ErbB4/HER4 exhibits unique attributes from a two step proteolytic cleavage which releases an 80 kilodalton, nuclear localizing, tyrosine kinase to a signal transduction mechanism that slows growth and stimulates differentiation of breast cells. This review provides an overview of ErbB4/HER4 in growth and differentiation of the mammary epithelium, including its physiologic role in development, the contrasting growth inhibition/tumor suppression and growth acceleration of distinct ErbB4/HER4 isoforms and a description of the unique cell cycle regulated pattern of nuclear HER4 ubiquitination and destruction

    Ack1 Mediated AKT/PKB Tyrosine 176 Phosphorylation Regulates Its Activation

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    The AKT/PKB kinase is a key signaling component of one of the most frequently activated pathways in cancer and is a major target of cancer drug development. Most studies have focused on its activation by Receptor Tyrosine Kinase (RTK) mediated Phosphatidylinositol-3-OH kinase (PI3K) activation or loss of Phosphatase and Tensin homolog (PTEN). We have uncovered that growth factors binding to RTKs lead to activation of a non-receptor tyrosine kinase, Ack1 (also known as ACK or TNK2), which directly phosphorylates AKT at an evolutionarily conserved tyrosine 176 in the kinase domain. Tyr176-phosphorylated AKT localizes to the plasma membrane and promotes Thr308/Ser473-phosphorylation leading to AKT activation. Mice expressing activated Ack1 specifically in the prostate exhibit AKT Tyr176-phosphorylation and develop murine prostatic intraepithelial neoplasia (mPINs). Further, expression levels of Tyr176-phosphorylated-AKT and Tyr284-phosphorylated-Ack1 were positively correlated with the severity of disease progression, and inversely correlated with the survival of breast cancer patients. Thus, RTK/Ack1/AKT pathway provides a novel target for drug discovery

    The HER4 Cytoplasmic Domain, But Not Its C Terminus, Inhibits Mammary Cell Proliferation

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    Unlike the proliferative action of other EGF receptor family members, HER4/ErbB4 is often associated with growth inhibitory and differentiation signaling. These actions may involve HER4 two-step proteolytic processing by intra-membraneous Ξ³-secretase, releasing the soluble, intracellular 80kDa HER4 cytoplasmic domain, s80HER4. We demonstrate that pharmacologic inhibition of either Ξ³-secretase activity or HER4 tyrosine kinase activity blocked heregulin-dependent growth inhibition of SUM44 breast cancer cells. We next generated breast cell lines stably expressing GFP-s80HER4 (GFP fused to the N-terminus of the HER4 cytoplasmic domain, residues 676–1308), GFP-CTHER4 (GFP fused to N-terminus of the HER4 C-terminus distal to the tyrosine kinase domain, residues 989–1308) or GFP alone. Both GFP-s80HER4 and GFP-CTHER4 were found in the nucleus, but GFP-s80HER4 accumulated to a greater extent and sustained its nuclear localization. s80HER4 was constitutively tyrosine phosphorylated and treatment of cells with a specific HER family tyrosine kinase inhibitor i) blocked tyrosine phosphorylation; ii) markedly diminished GFP-s80HER4 nuclear localization, and iii) reduced STAT5A tyrosine phosphorylation and nuclear localization as well as GFP-s80HER4:STAT5A interaction. Multiple normal mammary and breast cancer cell lines, stably expressing GFP-s80HER4 (SUM44, MDA-MB-453, MCF10A, SUM102, and HC11) were growth inhibited compared to the same cell line expressing GFP-CTHER4, or GFP alone. The s80HER4-induced cell number reduction was due to slower growth, as rates of apoptosis were equivalent in GFP, GFP-CTHER4, and GFP-s80HER4 expressing cells. Lastly, GFP-s80HER4 enhanced differentiation signaling as indicated by increased basal and prolactin-dependent β–casein expression. These results indicate that surface HER4 tyrosine phosphorylation and ligand-dependent release of s80HER4 are necessary, and s80HER4 signaling is sufficient for HER4-dependent growth inhibition

    Environmental change: prospects for conservation and agriculture in a southwest Australia biodiversity hotspot

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    Accelerating environmental change is perhaps the greatest challenge for natural resource management; successful strategies need to be effective for decades to come. Our objective is to identify opportunities that new environmental conditions may provide for conservation, restoration, and resource use in a globally recognized biodiversity hotspot in southwestern Australia. We describe a variety of changes to key taxonomic groups and system-scale characteristics as a consequence of environmental change (climate and land use), and outline strategies for conserving and restoring important ecological and agricultural characteristics. Opportunities for conservation and economic adaptation are substantial because of gradients in rainfall, temperature, and land use, extensive areas of remnant native vegetation, the ability to reduce and ameliorate areas affected by secondary salinization, and the existence of large national parks and an extensive network of nature reserves. Opportunities presented by the predicted environmental changes encompass agricultural as well as natural ecosystems. These may include expansion of aquaculture, transformation of agricultural systems to adapt to drier autumns and winters, and potential increases in spring and summer rain, carbon-offset plantings, and improving the network of conservation reserves. A central management dilemma is whether restoration/preservation efforts should have a commercial or biodiversity focus, and how they could be integrated. Although the grand challenge is conserving, protecting, restoring, and managing for a future environment, one that balances economic, social, and environmental values, the ultimate goal is to establish a regional culture that values the unique regional environment and balances the utilization of natural resources against protecting remaining natural ecosystems

    Missense Mutation in Exon 2 of SLC36A1 Responsible for Champagne Dilution in Horses

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    Champagne coat color in horses is controlled by a single, autosomal-dominant gene (CH). The phenotype produced by this gene is valued by many horse breeders, but can be difficult to distinguish from the effect produced by the Cream coat color dilution gene (CR). Three sires and their families segregating for CH were tested by genome scanning with microsatellite markers. The CH gene was mapped within a 6 cM region on horse chromosome 14 (LODβ€Š=β€Š11.74 for ΞΈβ€Š=β€Š0.00). Four candidate genes were identified within the region, namely SPARC [Secreted protein, acidic, cysteine-rich (osteonectin)], SLC36A1 (Solute Carrier 36 family A1), SLC36A2 (Solute Carrier 36 family A2), and SLC36A3 (Solute Carrier 36 family A3). SLC36A3 was not expressed in skin tissue and therefore not considered further. The other three genes were sequenced in homozygotes for CH and homozygotes for the absence of the dilution allele (ch). SLC36A1 had a nucleotide substitution in exon 2 for horses with the champagne phenotype, which resulted in a transition from a threonine amino acid to an arginine amino acid (T63R). The association of the single nucleotide polymorphism (SNP) with the champagne dilution phenotype was complete, as determined by the presence of the nucleotide variant among all 85 horses with the champagne dilution phenotype and its absence among all 97 horses without the champagne phenotype. This is the first description of a phenotype associated with the SLC36A1 gene

    HER4 D-Box Sequences Regulate Mitotic Progression and Degradation of the Nuclear HER4 Cleavage Product s80HER4

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    Heregulin-mediated activation of HER4 initiates receptor cleavage (releasing an 80-kDa HER4 intracellular domain, s80HER4, containing nuclear localization sequences) and results in G2/M delay by unknown signaling mechanisms. We report herein that s80HER4 contains a functional cyclin B-like sequence known as a D-box, which targets proteins for degradation by APC/C, a multisubunit ubiquitin ligase. s80HER4 ubiquitination and ptoteosomal degradation occurred during mitosis but not during S-phase. Inhibition of an APC subunit (APC2) using siRNA knock-down impaired s80HER4 degradation. Mutation of the s80HER4 D-box sequence stabilized s80HER4 during mitosis, and s80HER4-dependent growth inhibition via G2/M delay was significantly greater with the D-box mutant. Polyomvirus middle-T antigen-transformed HC11 cells expressing s80HER4 resulted in smaller, less proliferative, more differentiated tumors in vivo than those expressing kinase-dead s80HER4 or the empty vector. Cells expressing s80HER4 with a disrupted D-box did not form tumors, instead forming differentiated ductal structures. These results suggest that cell cycle-dependent degradation of s80HER4 limits its growth inhibitory action, and stabilization of s80HER4 enhances tumor suppression, thus providing a link between HER4-mediated growth inhibition and cell cycle control
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