Alzheimer's disease-associated R47H TREM2 increases, but wild-type TREM2 decreases, microglial phagocytosis of synaptosomes and neuronal loss

Triggering receptor on myeloid cells 2 (TREM2) is an innate immune receptor, upregulated on the surface of microglia associated with amyloid plaques in Alzheimer's disease (AD). Individuals heterozygous for the R47H variant of TREM2 have greatly increased risk of developing AD. We examined the effects of wild-type (WT), R47H and knock-out (KO) of human TREM2 expression in three microglial cell systems. Addition of mouse BV-2 microglia expressing R47H TREM2 to primary mouse neuronal cultures caused neuronal loss, not observed with WT TREM2. Neuronal loss was prevented by using annexin V to block exposed phosphatidylserine, an eat-me signal and ligand of TREM2, suggesting loss was mediated by microglial phagocytosis of neurons exposing phosphatidylserine. Addition of human CHME-3 microglia expressing R47H TREM2 to LUHMES neuronal-like cells also caused loss compared to WT TREM2. Expression of R47H TREM2 in BV-2 and CHME-3 microglia increased their uptake of phosphatidylserine-beads and synaptosomes versus WT TREM2. Human iPSC-derived microglia with heterozygous R47H TREM2 had increased phagocytosis of synaptosomes vs common-variant TREM2. Additionally, phosphatidylserine liposomes increased activation of human iPSC-derived microglia expressing homozygous R47H TREM2 versus common-variant TREM2. Finally, overexpression of TREM2 in CHME-3 microglia caused increased expression of cystatin F, a cysteine protease inhibitor, and knock-down of cystatin F increased CHME-3 uptake of phosphatidylserine-beads. Together, these data suggest that R47H TREM2 may increase AD risk by increasing phagocytosis of synapses and neurons via greater activation by phosphatidylserine and that WT TREM2 may decrease microglial phagocytosis of synapses and neurons via cystatin F.

Novel potent liposome agonists of triggering receptor expressed on myeloid cells 2 phenocopy antibody treatment in cells

The receptor Triggering Receptor Expressed on Myeloid cells 2 (TREM2) is associated with several neurodegenerative diseases including Alzheimer's Disease and TREM2 stimulation represents a novel therapeutic opportunity. TREM2 can be activated by antibodies targeting the stalk region, most likely through receptor dimerization. Endogenous ligands of TREM2 are suggested to be negatively charged apoptotic bodies, mimicked by phosphatidylserine incorporated in liposomes and other polyanionic molecules likely binding to TREM2 IgV fold. However, there has been much discrepancy in the literature on the nature of phospholipids (PLs) that can activate TREM2 and on the stability of the corresponding liposomes over time. We describe optimized liposomes as robust agonists selective for TREM2 over TREM1 in cellular system. The detailed structure/activity relationship studies of lipid polar heads indicate that negatively charged lipid heads are required for activity and we identified the shortest maximally active PL sidechain. Optimized liposomes are active on both TREM2 common variant and TREM2 R47H mutant. Activity and selectivity were further confirmed in different native TREM2 expressing cell types including on integrated cellular responses such as stimulation of phagocytic activity. Such tool agonists will be useful in further studies of TREM2 biology in cellular systems alongside antibodies, and in the design of small molecule synthetic TREM2 agonists.

Parallel All-Optical Assay to Study Use-Dependent Functioning of Voltage-Gated Ion Channels in a Miniaturized Format

Voltage-gated ion channels produce rapid transmembrane currents responsible for action potential generation and propagation at the neuronal, muscular, and cardiac levels. They represent attractive clinical targets because their altered firing frequency is often the hallmark of pathological signaling leading to several neuromuscular disorders. Therefore, a method to study their functioning upon repeated triggers at different frequencies is desired to develop new drug molecules selectively targeting pathological phenotype. Optogenetics provides powerful tools for millisecond switch of cellular excitability in contactless, physiological, and low-cost settings. Nevertheless, its application to large-scale drug-screening operations is still limited by long processing time (due to sequential well read), rigid flashing pattern, lack of online compound addition, or high consumable costs of existing methods. Here, we developed a method that enables simultaneous analysis of 384-well plates with optical pacing, fluorescence recording, and liquid injection. We used our method to deliver programmable millisecond-switched depolarization through light-activated opsin in concomitance with continuous optical recording by a fluorescent indicator. We obtained 384-well pacing of recombinant voltage-activated sodium or calcium channels, as well as induced pluripotent stem cell (iPSC)-derived cardiomyocytes, in all-optical parallel settings. Furthermore, we demonstrated the use-dependent behavior of known ion channel blockers by optogenetic pacing at normal or pathological firing frequencies, obtaining very good signal reproducibility and accordance with electrophysiology data. Our method provides a novel physiological approach to study frequency-dependent drug behavior using reversible programmable triggers. The all-optical parallel settings combined with contained operational costs make our method particularly suited for large-scale drug-screening campaigns as well as cardiac liability studies.

Three-Dimensional Control of Ion Channel Function through Optogenetics and Co-Culture

The lack of miniaturized and cost-effective methods to control cellular excitability with dosable and temporally precise electrical perturbations represents a long-lasting and unsolved bottleneck for ion channel drug discovery pipelines. Here we developed a high-throughput-compatible fluorescent-based cellular assay that combines optogenetics and co-culture approaches to obtain spatial, temporal, and quantitative control of ion channel activity. The modularity and increased flexibility of control of this light-tandem assay, combined with contained costs and compatibility with conventional drug-screening platforms, make this system suitable for temporally precise screening of ion channel function in controlled conformations and can also be used to recapitulate other complexly regulated biological processes.

A new electro-optical approach for conductance measurement: an assay for the study of drugs acting on ligand-gated ion channels

Ligand gated ion channels are involved in many pathophysiological processes and represent a relevant, although challenging, target for drug discovery. We propose an innovative electro-optical approach to their analysis able to derive membrane conductance values from the local membrane potential changes imposed by test current pulses and measured by fast voltage-sensitive fluorescent dyes. We exploited the potential of this proprietary method by developing a drug testing system called “ionChannel Optical High-content Microscope” (ionChannelΩ). This automated platform was validated by testing the responses of reference drugs on cells expressing different ligand-gated ion channels. Furthermore, a double-blind comparison with FLIPR and automated patch-clamp was performed on molecules designed to act as antagonists of the P2RX7 receptor. ionChannelΩ proved highly reliable in all tests, resulting faster and more cost-effective than electrophysiological techniques. Overall, ionChannelΩ is amenable to the study of ligand gated ion channels that are receiving less attention due to limitations in current assays.

GPR133 (ADGRD1), an adhesion G-protein-coupled receptor, is necessary for glioblastoma growth

Glioblastoma (GBM) is a deadly primary brain malignancy with extensive intratumoral hypoxia. Hypoxic regions of GBM contain stem-like cells and are associated with tumor growth and angiogenesis. The molecular mechanisms that regulate tumor growth in hypoxic conditions are incompletely understood. Here, we use primary human tumor biospecimens and cultures to identify GPR133 (ADGRD1), an orphan member of the adhesion family of G-protein-coupled receptors, as a critical regulator of the response to hypoxia and tumor growth in GBM. GPR133 is selectively expressed in CD133+ GBM stem cells (GSCs) and within the hypoxic areas of PPN in human biospecimens. GPR133 mRNA is transcriptionally upregulated by hypoxia in hypoxia-inducible factor 1α (Hif1α)-dependent manner. Genetic inhibition of GPR133 with short hairpin RNA reduces the prevalence of CD133+ GSCs, tumor cell proliferation and tumorsphere formation in vitro. Forskolin rescues the GPR133 knockdown phenotype, suggesting that GPR133 signaling is mediated by cAMP. Implantation of GBM cells with short hairpin RNA-mediated knockdown of GPR133 in the mouse brain markedly reduces tumor xenograft formation and increases host survival. Analysis of the TCGA data shows that GPR133 expression levels are inversely correlated with patient survival. These findings indicate that GPR133 is an important mediator of the hypoxic response in GBM and has significant protumorigenic functions. We propose that GPR133 represents a novel molecular target in GBM and possibly other malignancies where hypoxia is fundamental to pathogenesis.

A platform for high-throughput expression of recombinant human enzymes secreted by insect cells

Functional genomics and proteomics have been fields of intense investigation, since the disclosure of the sequence of the human genome. To contribute to the assignment of a physiological role to the vast number of coding genes with unknown function, we have undertaken a program to clone, express, purify and determine the catalytic activity of those enzymes predicted to enter the secretory pathway, focusing our efforts on human peptidases. Our strategy to promote high-throughput expression and purification of recombinant proteins secreted by insect cells relies on the expression of the target enzymes with their native leader sequences and on the carboxyl-terminal fusion with a poly-histidine tag. Growth of host cells were optimized in 24-well format to achieve highly paralleled culture conditions with production yields comparable to shake flask. The purification was performed by a robotic system in 96-well format using either magnetic beads or minicolumns. In a pilot study using reference peptidases and lipases, the high-throughput approach demonstrated to support the secretion in the insect cell medium of 85% of the sample enzymes. Of them, 66% have been proven to be catalytically active using fluorescent homogeneous assays in 384-well format compatible with the high-throughput screening criteria. The implications of these results are discussed in light of the application of this procedure to genomic-predicted peptidases.

Spontaneous uterine rupture with amniotic sac protrusion at 28 weeks subsequent to previous hysteroscopic metroplasty

BACKGROUND

Hysteroscopic metroplasty improves pregnancy outcome in case of uterine septum. Uterine rupture during a pregnancy following this procedure may occur.

CASE

A patient with a history of hysteroscopic resection of a uterine septum complicated by fundal perforation, presented at 28 weeks a spontaneous uterine rupture with amniotic sac protrusion through the uterine wall disruption.

CONCLUSION

Uterine rupture during pregnancy following a hysteroscopic metroplasty may occur even though it appears to be a very uncommon event. Patients who have had this procedure should be aware of this potential risk in case of future pregnancies. How to avoid such complication is still unclear.

[Endometrial carcinoma: prognostic significance of cellular ploidy]

BACKGROUND

The aim of the paper is to compare ploidy status with the traditional prognostic factors (grading, myometrial invasion, cytology of peritoneal fluid and node invasion) in 118 women affected by endometrial carcinoma and treated by hysterectomy in our department in order to evaluate a relationship between these parameters.

METHODS

Since January 1988 and August 1996 127 women (average age: 61) affected by endometrial carcinoma and not previously treated have been submitted to abdominal or vaginal hysterectomy. A retrospective study was carried out on 118 of these women evaluating DNA ploidy on fixed neoplastic samples through flow cytometry (Coulter Elite with Argon Laser). Aneuploidy was defined as cell population containing at the same time two or more moderate peaks in G0/G1. Histology of neoplastic tissues could evaluate grading and myometrial invasion in all cases. Cytology of peritoneal fluids and nodal state were evaluated respectively in 99 and 56 patients. The results obtained have been compared by Fisher's statistical test.

RESULTS

70.3% of evaluated neoplasias were diploid, while 29.7% were aneuploid. No statistical difference was observed comparing ploidy status with every considered parameter.

CONCLUSIONS

The results obtained show that DNA ploidy doesn't seem to be positively correlated with any traditional histopathological factors. The literature about this matter is questionable. Histopathological analysis is the only prognostic factor and it is the only parameter to personalize treatment.

Chromosomal localization and molecular characterization of 53 cosmid-derived bovine microsatellites

Gene mapping in cattle has progressed rapidly in recent years largely owing to the introduction of powerful genetic markers, such as the microsatellites, and through advances in physical mapping techniques such as synteny mapping and fluorescence in situ hybridization (FISH). Microsatellite markers are often not physically mapped because they are generally isolated from small insert plasmid libraries, which makes their chromosomal localization inefficient. In this report we describe the FISH mapping of a large group of cosmid-derived bovine microsatellite markers, as our contribution to the European mapping initiative, BovMap. One objective of BovMap is to develop a set of anchored loci for the cattle genome map. Two cosmid libraries were screened with probes corresponding to the (AC)n microsatellite motif. Positive clones were mapped by FISH, and then a subset was further analyzed by sequencing the region flanking the microsatellite repeat. In total, 58 clones were hybridized with chromosomes and identified loci on 22 of the 31 different bovine chromosomes. Three clones contained satellite DNA. Two or more markers were placed on 12 chromosomes. Sequencing of the microsatellites and flanking regions was performed directly from 43 cosmids, as previously reported (Ferretti et al. Anim. Genet. 25, 209-214, 1994). Primers were developed for 39 markers and used to describe the polymorphism associated with the corresponding loci.

Overexpression of p185 is not related to erbB2 amplification in ovarian cancer

BACKGROUND

While in breast cancer the amplification and overexpression of the erbB2 gene has been reported in numerous studies and found to be correlated to poor prognosis, information about this oncogene with respect to ovarian cancer is still limited. A recent study reported that approximately 30% of tumor biopsies from ovarian cancer patients exhibited erbB2 amplification and overexpression and suggested that the overexpression of this oncogene is an indicator of bad prognosis in ovarian cancer. The purpose of our studies was to investigate amplification of the erbB2 gene, the levels of erbB2 m-RNA and the erbB2 product (p185) in ovarian cancer, and the correlation between these findings and the pathological and clinical features.

RESULTS

Amplification of the erbB2 gene was investigated by Southern blot analysis in 75 samples from 62 patients; mRNA levels were evaluated by Northern blot analysis in 58 samples from 48 patients; and p185 was determined by immunohistochemistry in 65 samples from 65 patients. The erbB2 gene was amplified in only one case (1.6%), and a marked increase in erbB2 mRNA was found only in the same case. Staining for p185 was positive in 12 cases (18.5%). The staining was always confined to the cytoplasm except in the case that showed amplification of erbB2 in which p185 was localized in the membrane. No correlation was found between p185 positivity and pathological and clinical features or response to chemotherapy. Western blot analysis showed that the molecular weight of p185 in positive ovarian cancer cells was approximately 10 KDa lower than in breast cancer.

CONCLUSION

In contrast to breast cancer, in ovarian cancer the amplification of erbB2 appears infrequent. The levels of p185 detected by immunohistochemistry were not related to the amplification of the gene or to the increase in mRNA, suggesting the possibility of a longer half-life of the protein in the positive cases. The finding that erbB2 product in ovarian cancer is mostly localised in cytoplasm and not in the membrane as in breast cancer and that it has a lower molecular weight than the p185 in breast cancer suggest that this oncogene plays a different biological role in these two neoplasms.

Cis dichlorodiammine platinum induced DNA interstrand cross-links in primary cultures of human ovarian cancer

We quantified and examined the kinetics of DNA interstrand cross links (DNA-ISC) caused by Cis dichlorodiammine platinum (DDP) using the method of alkaline elution in 58 highly purified human ovarian tumours growing in primary culture. A large heterogeneity in both the quantity and kinetics of DDP induced DNA-ISC was observed in cultures derived from neoplasms of different patients and from different lesions of the same patient. In the majority of cases. DNA-ISC lasted for prolonged time intervals after 1 h drug exposure, being significantly repaired only 48 or 72 h following drug washout. The persistence of DNA-ISC is probably due to a prolonged formation of these lesions for up to 24 h as assessed by the change in the repair kinetics that occurred after preventing new DNA-ISC formation by quenching of monoadducts with thiourea. The inefficient repair of DDP monoadducts appears therefore to be a possible reason for the permanence of DNA-ISC. These studies suggest that the long permanence of DNA-ISC in human ovarian cancer could be the basis for the high selectivity of DDP for this human malignancy.