Melatonin-induced stimulation of rat corpus epididymal epithelial cell proliferation.

Stimulation of rat epididymal epithelial cell proliferation by melatonin was demonstrated by thymidine incorporation and flow cytometric analyses. The stimulatory effect of melatonin was dependent on the hormone concentration and the duration of cell exposure to the hormone. Maximal stimulation of [3H]thymidine incorporation into epididymal epithelial cells by melatonin was observed at 1 x 10(-9) M 5alpha-dihydrotestosterone in medium, while lower or higher concentrations of androgen attenuated the stimulatory effect of melatonin. Interestingly, a nuclear melatonin receptor agonist (1-[3-allyl-4-oxothiazolidine-2-ylidene]-4-methyl-thiosemi-carb azone, CGP 52608) induced opposite effect on epithelial cell proliferation to that produced by melatonin. Our data suggest that melatonin-induced stimulation of rat epididymal epithelial cell proliferation is not likely to be mediated by nuclear receptor. Furthermore, sequential changes of cell cycle distribution with melatonin treatment also supports a stimulatory action of melatonin on epididymal epithelial cell proliferation.     

Enhancement of DNA uptake in FUT8‐deleted CHO cells for transient production of afucosylated antibodies

Removal of the core α1,6 fucose from the glycans in the Fc region of IgG1 antibodies has been demonstrated to improve antibody‐dependent cellular cytotoxicity (ADCC) activity. In order to produce afucosylated antibodies using transient transfection, a FUT8 knockout (FUT8KO) cell line was generated in a CHO host cell line using the zinc finger nuclease technology. Transient transfection of DNA into mammalian cells using the cationic polymer, polyethylenimine (PEI), is commonly used for rapid generation of recombinant proteins. FUT8KO cells evaluated in PEI transfections yielded lower titers than parental CHO WT cells. FACS and HPLC analyses revealed that the FUT8KO cells had lower cell surface heparan sulfate (HS) levels than CHO WT. Removal of cell surface HS resulted in reduced uptake of PEI‐transfected DNA (PEI:DNA) and lower transfection titers suggesting that PEI:DNA relies on HS for binding and cellular entry. The absence of cell surface HS did not severely impact transfections performed with cationic liposomes. We undertook two approaches to improve transient production of afucosylated antibodies. First, we evaluated transfection of FUT8KO cells with cationic liposomes, which were observed to be less dependent on HS levels for uptake. Transfection of FUT8KO cells using the cationic liposome, DMRIE‐C, produced similar titers to CHO WT in both shake flask and large‐scale 10 L bioreactors. The second approach was to engineer a cell line overexpressing exostosin‐1 (EXT1), an enzyme responsible for HS chain elongation, to increase HS content. EXT1‐FUT8KO and CHO WT cells produced comparable levels of antibody from PEI transfections. Biotechnol. Bioeng. 2010;106: 751–763. © 2010 Wiley Periodicals, Inc.     

Activation of human bronchial epithelial cells by inflammatory cytokines IL‐27 and TNF‐α: Implications for immunopathophysiology of airway inflammation

Interleukin (IL)‐27 is a member of IL‐6/IL‐12 family cytokines produced by antigen‐presenting cells in immune responses. IL‐27 can drive the commitment of naive T cells to a T helper type 1 (Th1) phenotype and inhibit inflammation in later phases of infection. Human bronchial epithelial cells have been shown to express IL‐27 receptor complex. In this study, we investigated the in vitro effects of IL‐27, alone or in combination with inflammatory cytokine tumor necrosis factor (TNF)‐α on the pro‐inflammatory activation of human primary bronchial epithelial cells and the underlying intracellular signaling mechanisms. IL‐27 was found to enhance intercellular adhesion molecule 1 (ICAM‐1) expression on the surface of human bronchial epithelial cells, and a synergistic effect was observed in the combined treatment of IL‐27 and TNF‐α on the expression of ICAM‐1. Although IL‐27 did not alter the basal IL‐6 secretion from bronchial epithelial cells, it could significantly augment TNF‐α‐induced IL‐6 release. These synergistic effects on the up‐regulation of ICAM‐1 and IL‐6 were partially due to the elevated expression of TNF‐α receptor (p55TNFR) induced by IL‐27. Further investigations showed that the elevation of ICAM‐1 and IL‐6 in human bronchial epithelial cells stimulated by IL‐27 and TNF‐α was differentially regulated by phosphatidylinositol 3‐OH kinase (PI3K)‐Akt, p38 mitogen‐activated protein kinase, and nuclear factor‐κB pathways. Our results therefore provide a new insight into the molecular mechanisms involved in airway inflammation. J. Cell. Physiol. 223:788–797, 2010. © 2010 Wiley‐Liss, Inc.     

SARS-CoV-2 RNA screening in routine pathology specimens

Virus detection methods are important to cope with the SARS-CoV-2 pandemics. Apart from the lung, SARS-CoV-2 was detected in multiple organs in severe cases. Less is known on organ tropism in patients developing mild or no symptoms, and some of such patients might be missed in symptom-indicated swab testing. Here, we tested and validated several approaches and selected the most reliable RT-PCR protocol for the detection of SARS-CoV-2 RNA in patients’ routine diagnostic formalin-fixed and paraffin-embedded (FFPE) specimens available in pathology, to assess (i) organ tropism in samples from COVID-19-positive patients, (ii) unrecognized cases in selected tissues from negative or not-tested patients during a pandemic peak, and (iii) retrospectively, pre-pandemic lung samples. We identified SARS-CoV-2 RNA in seven samples from confirmed COVID-19 patients, in two gastric biopsies, one small bowel and one colon resection, one lung biopsy, one pleural resection and one pleural effusion specimen, while all other specimens were negative. In the pandemic peak cohort, we identified one previously unrecognized COVID-19 case in tonsillectomy samples. All pre-pandemic lung samples were negative. In conclusion, SARS-CoV-2 RNA detection in FFPE pathology specimens can potentially improve surveillance of COVID-19, allow retrospective studies, and advance our understanding of SARS-CoV-2 organ tropism and effects.     

Pharmacology of insect GABA receptors

A GABA-operated Cl^– channel that is bicuculline-insensitive is abundant in the nervous tissue of cockroach, in housefly head preparations and thorax/abdomen preparations, and in similar preparations from several insect species. Bicuculline-insensitive GABA-operated Cl^– channels, which are rare in vertebrates, possess sites of action of benzodiazepines, steroids and insecticides that are pharmacologically-distinct from corresponding sites on vertebrate GABA_A receptors. The pharmacological profile of the benzodiazepine-binding site linked to an insect CNS GABA-operated Cl^– channel resembles more closely that of vertebrate peripheral benzodiazepine-binding sites. Six pregnane steroids and certain polychlorocycloalkane insecticides, which are active att-butylbicy-clophosphorothionate (TBPS)-binding sites, also differ in their effectiveness on vertebrate and insect GABA receptors. Radioligand binding and physiological studies indicate that in insects there may be subtypes of the GABA receptor. Molecular biology offers experimental approaches to understanding the basis of this diversity.Special issue dedicated to Dr. Eugene Roberts     

cDNA and gene structure for a human subtilisin-like protease with cleavage specificity for paired basic amino acid residues.

A cDNA encoding the human fur gene product was isolated from a human hepatoma cell line. The cDNA encodes a protein with significant amino acid sequence identity to the prokaryotic subtilisin family of serine proteases. More extensive sequence identity was found when the protein was compared with eukaryotic proteases such as PRB1 of Saccharomyces cerevisiae, and with PC2 and PC3, the only other known mammalian subtilisin-like proteases. In contrast to these proteins, however, the fur gene product shares a more extensive topographic and functional homology with the KEX2 endoprotease of S. cerevisiae. Each protease contains a signal peptide, a glycosylated extra cytoplasmic domain, a hydrophobic membrane-spanning region, and a short, hydrophilic "tail" sequence. As with KEX2, the expressed human protease was shown to cleave mammalian proproteins at their paired basic amino acid processing sites. We have, therefore, proposed the function-based acronym PACE (paired basic amino acid cleaving enzyme) for this prototypic mammalian proprotein processing enzyme.     

Holding back the microfilament--structural insights into actin and the actin-monomer-binding proteins of apicomplexan parasites

Parasites from the phylum Apicomplexa are responsible for several major diseases of man, including malaria and toxoplasmosis. These highly motile protozoa use a conserved actomyosin-based mode of movement to power tissue traversal and host cell invasion. The mode termed as 'gliding motility' relies on the dynamic turnover of actin, whose polymerisation state is controlled by a markedly limited number of identifiable regulators when compared with other eukaryotic cells. Recent studies of apicomplexan actin regulator structure-in particular those of the core triad of monomer-binding proteins, actin-depolymerising factor/cofilin, cyclase-associated protein/Srv2, and profilin-have provided new insights into possible mechanisms of actin regulation in parasite cells, highlighting divergent structural features and functions to regulators from other cellular systems. Furthermore, the unusual nature of apicomplexan actin itself is increasingly coming into the spotlight. Here, we review recent advances in understanding of the structure and function of actin and its regulators in apicomplexan parasites. In particular we explore the paradox between there being an abundance of unpolymerised actin, its having a seemingly increased potential to form filaments relative to vertebrate actin, and the apparent lack of visible, stable filaments in parasite cells.     

The development, application and limitations of breast cancer cell lines to study tamoxifen and aromatase inhibitor resistance

Estrogen plays important roles in hormone receptor-positive breast cancer. Endocrine therapies, such as the antiestrogen tamoxifen, antagonize the binding of estrogen to estrogen receptor (ER), whereas aromatase inhibitors (AIs) directly inhibit the production of estrogen. Understanding the mechanisms of endocrine resistance and the ways in which we may better treat these types of resistance has been aided by the development of cellular models for resistant breast cancers. In this review, we will discuss what is known thus far regarding both de novo and acquired resistance to tamoxifen or AIs. Our laboratory has generated a collection of AI- and tamoxifen-resistant cell lines in order to comprehensively study the individual types of resistance mechanisms. Through the use of microarray analysis, we have determined that our cell lines resistant to a particular AI (anastrozole, letrozole, or exemestane) or tamoxifen are distinct from each other, indicating that these mechanisms can be quite complex. Furthermore, we will describe two novel de novo AI-resistant cell lines that were generated from our laboratory. Initial characterization of these cells reveals that they are distinct from our acquired AI-resistant cell models. In addition, we will review potential therapies which may be useful for overcoming resistant breast cancers through studies using endocrine resistant cell lines. Finally, we will discuss the benefits and shortcomings of cell models. Together, the information presented in this review will provide us a better understanding of acquired and de novo resistance to tamoxifen and AI therapies, the use of appropriate cell models to better study these types of breast cancer, which are valuable for identifying novel treatments and strategies for overcoming both tamoxifen and AI-resistant breast cancers.     

Gestational hypertension and the developmental origins of cardiac hypertrophy and diastolic dysfunction

The developmental origins of health and disease refer to the theory that adverse maternal environments influence fetal development and the risk of cardiovascular disease in adulthood. We used the chronically hypertensive atrial natriuretic peptide knockout (ANP?/?) mouse as a model of gestational hypertension, and attempted to determine the effect of gestational hypertension on left ventricular (LV) structure and function in adult offspring. We crossed normotensive ANP+/+ females with ANP?/? males (yielding ANP+/?^WT offspring) and hypertensive ANP?/? females with ANP+/+ males (yielding ANP+/?^KO offspring). Cardiac gene expression was measured using real-time quantitative PCR. Cardiac function was assessed using echocardiography. Daily injections of isoproterenol (ISO) were used to induce cardiac stress. Collagen deposition was assessed using picrosirius red staining. All mice were 10 weeks of age. Gestational hypertension resulted in significant LV hypertrophy in offspring, with no change in LV function. Treatment with ISO resulted in significant LV diastolic dysfunction with a restrictive filling pattern (increased E/A ratio and E/e′) and interstitial myocardial fibrosis only in ANP+/?^KO and not ANP+/?^WT offspring. Gestational hypertension programs adverse LV structural and functional remodeling in offspring. These data suggest that adverse maternal environments may increase the risk of heart failure in offspring later in life.