mCherry Expression Research Articles

Plasmodium transcription repressor AP2-O3 regulates sex-specific identity of gene expression in female gametocytes.

Male and female gametocytes are sexual precursor cells essential for mosquito transmission of malaria parasite. Differentiation of gametocytes into fertile gametes (known as gametogenesis) relies on the gender‐specific transcription program. How the parasites establish distinct repertoires of transcription in the male and female gametocytes remains largely unknown. Here, we report that an Apetala2 family transcription factor AP2‐O3 operates as a transcription repressor in the female gametocytes. AP2‐O3 is specifically expressed in the female gametocytes. AP2‐O3‐deficient parasites produce apparently normal female gametocytes. Nevertheless, these gametocytes fail to differentiate into fully fertile female gametes, leading to developmental arrest in fertilization and early development post‐fertilization. AP2‐O3 disruption causes massive upregulation of transcriptionally dormant male genes and simultaneously downregulation of highly transcribed female genes in the female gametocytes. AP2‐O3 targets a substantial proportion of the male genes by recognizing an 8‐base DNA motif. In addition, the maternal AP2‐O3 is removed after fertilization, which is required for the zygote to ookinete development. Therefore, the global transcriptional repression of the male genes in the female gametocytes is required for safeguarding female‐specific transcriptome and essential for the mosquito transmission of Plasmodium.

Generation of an EFNB2-2A-mCherry reporter human embryonic stem cell line using CRISPR/Cas9-mediated site-specific homologous recombination.

Ephrin B2 (EFNB2) is the first identified and most widely used marker for arterial endothelial cells (AECs). We generated a heterozygous EFNB2-2A-mCherry reporter H1 cell line, H1-EFNB2-2A-mCherry+/- (WAe001-A-57), by CRISPR/Cas9-mediated insertion of 2A-mCherry cassette into the EFNB2 gene locus, immediately before the translation stop codon. The H1-EFNB2-2A-mCherry reporter cells were pluripotent and could differentiate into all three germ layer lineages. Simultaneous expression of mCherry was observed when expression of EFNB2 was increased during endothelial cell differentiation. Thus, the generated reporter cells enable live identification of EFNB2-positive AECs, and screening of small molecule compound and target genes that promote AEC differentiation.

Untersuchung von molekularen Mechanismen der Virusreplikation in Echtzeit

Viral replication is a crucial step in the virus life cycle and for the determination of its pathogenicity and can be investigated in a microplate assay by monitoring viral gene expression. As an illustrative example, the Sindbis virus (SINV, Alphavirus genus) with an engineered genome containing the coding sequence for mCherry fluorescent protein was used. Expression of mCherry can be used as a proxy for viral gene expression and can be measured at regular intervals throughout the infection to simulate viral replication.

Lentiviral transduction facilitates RNA interference in the nematode parasite Nippostrongylus brasiliensis.

Animal-parasitic nematodes have thus far been largely refractory to genetic manipulation, and methods employed to effect RNA interference (RNAi) have been ineffective or inconsistent in most cases. We describe here a new approach for genetic manipulation of Nippostrongylus brasiliensis, a widely used laboratory model of gastrointestinal nematode infection. N. brasiliensis was successfully transduced with Vesicular Stomatitis Virus glycoprotein G (VSV-G)-pseudotyped lentivirus. The virus was taken up via the nematode intestine, RNA reverse transcribed into proviral DNA, and transgene transcripts produced stably in infective larvae, which resulted in expression of the reporter protein mCherry. Improved transgene expression was achieved by incorporating the C. elegans hlh11 promoter and the tbb2 3´-UTR into viral constructs. MicroRNA-adapted short hairpin RNAs delivered in this manner were processed correctly and resulted in partial knockdown of β-tubulin isotype-1 (tbb-iso-1) and secreted acetylcholinesterase B (ache-B). The system was further refined by lentiviral delivery of double stranded RNAs, which acted as a trigger for RNAi following processing and generation of 22G-RNAs. Virus-encoded sequences were detectable in F1 eggs and third stage larvae, demonstrating that proviral DNA entered the germline and was heritable. Lentiviral transduction thus provides a new means for genetic manipulation of parasitic nematodes, including gene silencing and expression of exogenous genes.

AAV vectors to study the functional consequences of neuronal and astrocytic tau pathology using in vivo 2‐photon imaging

AbstractBackgroundTau pathology is a defining histopathological feature of Alzheimer’s disease (AD) and primary tauopathies such as progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD). Whereas AD is mostly characterized by neuronal tau pathology, primary tauopathies such as PSP and CBD also present with glial tau pathology. How tau pathology affects the activity of distinct neuronal cell types (e.g. interneurons) or glial cells (e.g. astrocytes) is currently unknown. We have developed adeno‐associated virus (AAV)‐based tauopathy models of neuronal and astrocytic tau pathology to study the functional consequences of tau pathology using in vivo 2‐photon imaging.MethodWe present AAV vectors expressing human truncated tau (amino acids 151‐391/4R) and red fluorophore mCherry in equal ratio under the neuronal human synapsin promotor (AAV‐hSyn‐htTau) or the astrocytic GFAP promotor (AAV‐GFAP‐htTau). AAVs expressing only mCherry under the same promotors were used as controls. AAVs were injected into the hippocampus of wild‐type mice for histological, biochemical, and behavioral characterization.AAV‐hSyn‐htTau was injected intracerebroventricularly in PV‐Cre mice to study the effects of tau pathology on pyramidal neurons or interneurons using in vivo 2‐photon calcium imaging. AAV‐GFAP‐htTau was injected into the cortex of wild‐type or CX3CR1‐YFP mice to study the effects of astrocytic tau pathology on neuronal activity or microglia using in vivo imaging, respectively.ResultAAV‐hSyn‐htTau and AAV‐GFAP‐htTau both induced widespread expression of mCherry and hyperphosphorylated tau in neurons or astrocytes, respectively. Only the neuronal model induced abundant sarkosyl insoluble tau and methoxy‐XO4+ aggregated tau. In vivo 2‐photon calcium imaging of cortical neurons revealed increased spiking activity in truncated tau‐expressing PV+ interneurons, but not in pyramidal cells, suggesting that tau‐mediated alteration of interneuron activity is an early pathological event. No cognitive impairments were detected at early timepoints.Astrocytic tau pathology led to inflammatory changes of blood vessels, such as upregulation of adhesion molecules VCAM1 and ICAM1. No changes in cognition or neuronal spiking activity were detected at the examined timepoints. Analysis of microglial morphology and motility is currently ongoing.ConclusionAAV‐based tauopathy models are attractive tools to study the consequences of neuronal and glial tau pathology in vivo. Funding: VEGA 2/0135/18 and SyDAD (Horizon 2020, 676144)

Encapsulation of mRNA into Artificial Viral Capsids via Hybridization of a β-Annulus-dT20 Conjugate and the Poly(A) Tail of mRNA

Messenger RNA (mRNA) drugs have attracted considerable attention as promising tools with many therapeutic applications. The efficient delivery of mRNA drugs using non-viral materials is currently being explored. We demonstrate a novel concept where mCherry mRNA bearing a poly(A) tail is encapsulated into capsids co-assembled from viral β-annulus peptides bearing a 20-mer oligothymine (dT20) at the N-terminus and unmodified peptides via hybridization of dT20 and poly(A). Dynamic light scattering measurements and transmission electron microscopy images of the mRNA-encapsulated capsids show the formation of spherical assemblies of approximately 50 nm. The encapsulated mRNA shows remarkable ribonuclease resistance. Further, modification by a cell-penetrating peptide (His16) on the capsid enables the intracellular expression of mCherry of encapsulated mRNA.

Development and characterization of recombinant tick-borne encephalitis virus expressing mCherry reporter protein: A new tool for high-throughput screening of antiviral compounds, and neutralizing antibody assays

The flavivirus, tick-borne encephalitis virus (TBEV) is transmitted by Ixodes spp. ticks and may cause severe and potentially lethal neurological tick-borne encephalitis (TBE) in humans. Studying TBEV requires the use of secondary methodologies to detect the virus in infected cells. To overcome this problem, we rationally designed and constructed a recombinant reporter TBEV that stably expressed the mCherry reporter protein. The resulting TBEV reporter virus (named mCherry-TBEV) and wild-type parental TBEV exhibited similar growth kinetics in cultured cells; however, the mCherry-TBEV virus produced smaller plaques. The magnitude of mCherry expression correlated well with progeny virus production but remained stable over <4 passages in cell culture. Using well-characterized antiviral compounds known to inhibit TBEV, 2′-C-methyladenosine and 2′-deoxy-2′-β-hydroxy-4′-azidocytidine (RO-9187), we demonstrated that mCherry-TBEV is suitable for high-throughput screening of antiviral drugs. Serum samples from a TBEV-vaccinated human and a TBEV-infected dog were used to evaluate the mCherry-based neutralization test. Collectively, recombinant mCherry-TBEV reporter virus described here provides a powerful tool to facilitate the identification of potential antiviral agents, and to measure levels of neutralizing antibodies in human and animal sera.

Development of matured hiPSCs-derived 3D cardiac tissue using ERR gamma agonist and mechanical stress and application for Hypertrophic Cardiomyopathy (HCM) model

Abstract Introduction Tissue engineering using human induced pluripotent stem cells-derived cardiomyocytes (hiPSCs-CMs) is one of the potential tools to replicate human heart in vitro. Although there are many publications on 3 dimensional (3D) heart tissues (1), these tissues show fetal like phenotypes. For that reason, several maturation methods such as electrical stimulation and mechanical stress have been investigated (2, 3). However, these methods have been inadequate in differentiating fetal like phenotype tissue from adult tissues. Previously, we identified a novel compound, T112, which induced hiPSCs-CMs maturation from approximately 9,000 compounds using Troponin I1-EmGFP and Troponin I3-mCherry double reporter hiPSCs-CMs. This compound enhanced morphological and metabolic maturation of hiPSCs-CMs via estrogen-rerated receptor gamma activation Purpose We hypothesized that our novel compound, T112, in combination with mechanical stress could result in further maturation of 3D heart tissue. Therefore, our specific aim is to develop a novel maturation method applicable to genetic disease model of HCM using 3D heart tissue combined with T112. Methods We constructed 3D heart tissue mixed with fibroblast and double reporter hiPSCs-CMs by the hydrogel methods using Flex cell system®. We added T112 with or without mechanical stretching to 3D tissue from 7 to 15 days after 3D heart tissue was constructed. Then we measured maturation related phenotype such as sarcomere gene expression, mitochondrial DNA content and cell size. Results Similar to hiPSCs-CM, the addition of T112 to the constructed 3D heart tissue significantly increased TNNI3 mRNA compared to that of DMSO. Furthermore, T112 treated 3D heart tissue showed increased cell size and oblong shape. Next, in order to promote more maturation of 3D heart tissue, we performed mechanical stretching with the addition of T112. The combination of T112 with mechanical stretching showed higher expression of mCherry, a reporter protein for TNNI3 expression, and higher isotropy of sarcomere alignment in 3D heart tissue than that with the static condition. Furthermore, 3D heart tissue in the treatment of T112 with or without mechanical stretching showed higher mitochondrial DNA content compared to the respective DMSO controls. Interestingly, we applied this combination method to hiPSCs carrying MYH7 R719Q mutation which is known to cause hypertrophic cardiomyopathy, and the 3D heart tissue composed of cardiomyocytes derived from mutant iPSCs demonstrated increased sarcomere disarray compared to isogenic wild-type 3D heart tissue. Conclusion These results suggest that the combination of T112 and mechanical stretching promotes metabolic and structural maturation of 3D heart tissue and would be useful for creating a HCM disease model. Funding Acknowledgement Type of funding source: Private company. Main funding source(s): T-CiRA project, Takeda Pharmaceutical Company Limited

Leishmania infantum transfected with toxic plasmid induces protection in mice infected with wild type L. infantum or L. amazonensis

Leishmania infantum infection may cause visceral leishmaniasis (VL), a fatal disease having worldwide distribution, that may be silent or asymptomatic. The latter indicates that immunity is naturally developed in some individuals, and, therefore, a vaccine against VL would be possible. Molecular mechanisms of gene expression are being understood in Leishmania, and this knowledge may be useful for vaccine development. The aim of this study was developing an attenuated strain by regulating the expression of toxic proteins in a stage specific manner. For that purpose, the 3’ UTR of an amastin gene, known by its increased expression in the amastigote phase, was selected for direct the expression of exogenous proteins. This construct (pFL-AMA), firstly, was proved effective for the expression of mCherry specifically in the intracellular form of L. infantum, as demonstrated by fluorescence microscopy, flow cytometry and Western blotting. Afterwards, mCherry coding sequence was replaced, in the pFL-AMA plasmid, by either egg avidin or the active form of bovine trypsin. Viability of transfected parasites was evaluated in promastigote axenic cultures and in in vitro infection of macrophages. Both lines of transfected parasites showed a limited capacity to multiply inside macrophages. BALB/c mice were inoculated intraperitoneally (i.p.) with a single dose consisting of 2 × 106L. infantum promastigotes transfected with plasmids bearing the toxic genes. After 10 weeks post-inoculation, no parasites were recovered by limiting dilution in either liver or spleen, but a specific immunological response was detected. The immunization with transfected parasites induced cellular and humoral immune responses with activation of TCD4+, TCD8+ and B cells, having a TH1-type response with increased levels of pro-inflammatory cytokines such as IFN-γ, TNF-α and IL-6. In parallel groups of mice, a challenge consisting on 1 × 106 virulent parasites of either L. infantum (inoculated i.p.) or L. amazonensis subcutaneously (s.c.) was performed. Vaccinated mice, challenged with L. infantum, showed lower parasite burdens in liver, spleen and bone marrow than infected mice with WT L. infantum (non-vaccinated); similarly, vaccinated mice developed smaller footpad inflammation than control group. These data support this strategy as an efficient immunization system aimed to the development of vaccines against different forms of leishmaniasis.

TATA Binding Protein (TBP) Promoter Drives Ubiquitous Expression of Marker Transgene in the Adult Sea Anemone Nematostella vectensis.

Nematostella vectensis has emerged as one as the most established models of the phylum Cnidaria (sea anemones, corals, hydroids and jellyfish) for studying animal evolution. The availability of a reference genome and the relative ease of culturing and genetically manipulating this organism make it an attractive model for addressing questions regarding the evolution of venom, development, regeneration and other interesting understudied questions. We and others have previously reported the use of tissue-specific promoters for investigating the function of a tissue or a cell type of interest in vivo. However, to our knowledge, genetic regulators at the whole organism level have not been reported yet. Here we report the identification and utilization of a ubiquitous promoter to drive a wide and robust expression of the fluorescent protein mCherry. We generated animals containing a TATA binding protein (TBP) promoter upstream of the mCherry gene. Flow cytometry and fluorescent microscopy revealed expression of mCherry in diverse cell types, accounting for more than 90% of adult animal cells. Furthermore, we detected a stable mCherry expression at different life stages and throughout generations. This tool will expand the existing experimental toolbox to facilitate genetic engineering and functional studies at the whole organism level.

A dengue type 2 reporter virus assay amenable to high-throughput screening

Dengue virus (DV) is an important mosquito-borne flavivirus threatening almost half of the world's population. Prophylaxis and potent anti-DV drugs are urgently needed. Here, we developed a high content imaging-based (HCI) assay with DV type 2 expressing the fluorescent protein mCherry (DV2/mCherry) to improve the efficiency and robustness of the drug discovery process. For the construction of the reporter virus, the mCherry gene followed by the ribosome-skipping 2A sequence of the Thosea asigna virus (T2A) was placed upstream of the full DV2 open reading frame. The biological characteristics including mCherry expression, virus replication rate, and plaque phenotype was examined and validated in BHK-21, Vero and C6/36 cells. A robust image-based antiviral assay combined with an automated robotic system was then developed, with a Z′ factor of 0.73. To validate the image-based antiviral assay, a panel of reference compounds with different molecular mechanisms of anti-DV activity was assessed: (i) the glycosylation inhibitor, Celgosivir, (ii) two NS4b-targeting compounds: a 3-Acyl-indole derivative and NITD618, and (iii) two nucleoside viral polymerase inhibitors, 2′CMC and 7DMA. The inhibition profiles were quantified and obtained by means of HCI and RT-qPCR. Both methods resulted in very comparable inhibition profiles. In conclusion, a powerful and robust assay was developed with a fully automated data generation and processing pipeline. It makes the new reporter virus assay amenable to high-throughput screening of large libraries of small molecules.

Development of a novel secondary phenotypic screen to identify hits within the mycobacterial protein synthesis pipeline.

BackgroundWhole‐cell phenotypic screening is the driving force behind modern anti‐tubercular drug discovery efforts. Focus has shifted from screening for bactericidal scaffolds to screens incorporating target deconvolution. Target‐based screening aims to direct drug discovery toward known effective targets and avoid investing resources into unproductive lines of enquiry. The protein synthesis pipeline, including RNA polymerase and the ribosome, is a clinically proven target in Mycobacterium tuberculosis. Screening for new hits of this effective target pathway is an invaluable tool in the drug discovery arsenal.MethodsUsing M. tuberculosis H37Rv augmented with anhydrotetracycline‐inducible expression of mCherry, a phenotypic screen was developed for the identification of protein synthesis inhibitors in a medium throughput screening format.ResultsThe assay was validated using known inhibitors of protein synthesis to show a dose‐dependent reduction in mCherry fluorescence. This was expanded to a proprietary screen of hypothetical protein synthesis hits and modified to include quantitative viability measurement of cells using resazurin.ConclusionFollowing the success of the proprietary screen, a larger scale screen of the GlaxoSmithKline anti‐tubercular library containing 2799 compounds was conducted. Combined single shot and dose‐response screening yielded 18 hits, 0.64% of all screened compounds.

A novel approach to genetic engineering of T-cell subsets by hematopoietic stem cell infection with a bicistronic lentivirus

Lentiviral modification of hematopoietic stem cells (HSCs) paved the way for in vivo experimentation and therapeutic approaches in patients with genetic disease. A disadvantage of this method is the use of a ubiquitous promoter leads not only to genetic modification of the leukocyte subset of interest e.g. T-cells, but also all other subsequent leukocyte progeny of the parent HSCs. To overcome this limitation we tested a bicistronic lentivirus, enabling subset specific modifications. Designed novel lentiviral constructs harbor a global promoter (mPGK) regulating mCherry for HSCs selection and a T-cell specific promoter upstream of eGFP. Two T-cell specific promoters were assessed: the distal Lck—(dLck) and the CD3δ-promoter. Transduced HSCs were FACS sorted by mCherry expression and transferred into sublethally irradiated C57/BL6 mice. Successful transplantation and T-cell specific expression of eGFP was monitored by peripheral blood assessment. Furthermore, recruitment response of lentiviral engineered leukocytes to the site of inflammation was tested in a peritonitis model without functional impairment. Our constructed lentivirus enables fast generation of subset specific leukocyte transgenesis as shown in T-cells in vivo and opens new opportunities to modify other HSCs derived subsets in the future.

Heat-shock-induced tyrosinase gene ablation with CRISPR in zebrafish.

Tyrosinase (TYR) converts L-tyrosine into 3,4-dihydroxyphenylalanine (L-DOPA) and L-DOPA into L-dopaquinone, which can produce melanin pigment. The abrogation of the functional activity of TYR can result in albino skin and eye diseases because of a deficiency in melanin pigment production. In this study, we developed and characterized an inducible knockout TYR platform comprising the heat-inducible heat-shock-promoter-70-driving CRISPR/Cas9 system and a zU6-promoter-driving tyr single guide RNA (sgRNA) system to investigate the temporal expression of TYR genes. To overcome the difficulty of identifying zebrafish germline integrations and facilitate the observation of Cas9 expression, heart-specific cmlc2:enhanced green fluorescent protein (EGFP; used to confirm tyr sgRNA expression) and two selectable markers (P2A-mCherry and internal ribosomal entry site-EGFP) were applied in our system. Heat shock treatment administered to Cas9 transgenic embryos induced mCherry or EGFP fluorescence expression throughout the embryos' bodies, and Cas9 protein was detected 1h after heat shock treatment. Mutations were created by direct injection and line crossing, which led to mosaic and complete depigmentation phenotypes in approximately 50% and 100% of the embryos, respectively. Using our system, conditional TYR knockout in zebrafish was achieved efficiently and simply.

Construction of a Novel, Dual, Self-Replicating Minicircle; an Efficient Tool in Transdifferentiation

Background & Aim Minicircles (MCs) are circular DNAs contain minimal eukaryotic expression cassette (EEC) devoid of bacterial backbone (BB). Due to low-toxicity and Immunogenicity of Minicircles, these vectors could serve as an attractive alternative in therapeutic applications such as DNA vaccines, pluripotent cells or gene-based therapies. The inclusion of scaffold/matrix attachment region (S/MAR) elements in minicircles can increase long-term expression of transgene in the dividing cells. In this study we constructed a dual reporter minicircle (DR-MC) containing an S/MAR element and two different reporter genes, mCherry and EGFP, which express in different stages after transfection into eukaryotic cells. First reporter gene is flanked by two Lox recognition sites and after adequate level of expression removes by the intramolecular Cre-madiated recombination. So, the second reporter locate adjacent to promoter and express. Reporter genes could be replaced by the gene of interests, involving in transdifferentiation. Methods, Results & Conclusion Two different fragments were amplified by PCR, loxP-mCherry-BGHpA-loxH (LML) and EGFP-SMAR-SV40pA-SV40promoter (ESS), which respectively were cloned between attB-attP sites of parental plasmid (PP-LML-ESS). Minicircle producing bacteria (ZYCY10P3S2T) were transformed with PP-LML-ESS, producing DR-MCs after induction by L-Arabinose. DR-MCs were transfected into HEK293T cells and mCherry expression was assessed by fluorescent microscopy and Flow cytometry. Tat-NLS-Cre recombinase was added to transfected cell's culture medium and EGFP expression was measured in several time points. Reporter-expressing cells were picked up to generate stable cell lines, evaluated by qRT-PCR and FISH analysis to determine the episomal state of MCs and copy numbers. The accuracy of constructed PP-LML-ESS and DR-MC was determined by restriction digestion. mCherry expression in transfected HEK293T cells confirmed the elimination of BB. Tat-NLS-Cre recombinase led to mCherry excision and EGFP expression. By tracking reporter-expressing cell lines after several passages we realized that DR-MC could replicate episomaly with maintained copy numbers. In conclusion DR-MCs propose safe, long-term and efficient systems which could carry several genes with adjustable expression time points. These characteristics enable DR-MCs to be used in cell's lineage reprogramming, in which one mature somatic cell transforms into another mature somatic cell with different gene expression profile.

A Fluorescent Based System to Monitor 2‐micron Copy Number in Saccharomyces cerevisiae

The 2‐micron plasmid is a small genetic element that persists in Saccharomyces cerevisiae with chromosome like stability. It encodes for four proteins (Rep1, Rep2, Raf1, and Flp) that appear to provide no advantage for the host cell, but instead have a role in replicating and maintaining a steady state concentration of the plasmid‐‐ 1. Flp recombinase is known to promote amplification of the 2‐micron; disruption of the FLP gene is a valid way of preventing the necessary amplification of the plasmid to pass itself on. The 2‐micron is a selfish DNA element that is able to maintain a copy number of 40–60, however its ability to maintain these levels is not completely understood. To study this regulation we have established a quantitative and efficient means to monitor copy number. We used CRISPR‐Cas9 to replace ADE2 (encoded on 2‐micron/ADE22) with mCherry, enabling copy number to be monitored using flow cytometry. Preparation of the strains required no additional staining, allowing for quick processing and analysis. To establish the sensitivity of the system, mCherry expression was monitored in strains that had ectopic expression of the flp‐H305L mutant, which destabilizes the 2‐micron plasmid 2. We observed a decrease in mCherry expression in these strains, consistent with the role Flp plays in 2‐micron amplification. This reduction in copy number was confirmed using quantitative PCR to examine expression of mCherry from the 2‐micron. Current studies are employing this system to monitor how copy number is affected by two long non‐coding RNAs (lncRNA), which are expressed from the plasmid and regulated by Rrp6p and the TRAMP complex, components of the nuclear RNA surveillance pathway.Support or Funding InformationSJFC internal funds

The ciliary localized GPCR, MCHR1, modulates odor responses in the olfactory bulb

The sense of smell is essential for maintaining full human health and quality of life. It plays an important role in the detection of environmental dangers as well guiding decisions such as what foods to eat. However, olfactory processing is influenced by the physiological state of an organism. Physiological changes such can be integrated in the hypothalamus, through populations of neurons expressing various neuropeptides. One of these peptides is melanin‐concentrating hormone (MCH) which functions in both promoting feeding and sleep. Neurons expressing MCH project to several areas of the brain including the olfactory bulb (OB), where the MCH receptor, MCHR1, a g‐protein coupled receptor, is expressed. MCH signaling has been implicated in olfactory driven behaviors, however the mechanism by which it does so is unknown. In rodents, there is a single MCH receptor, MCHR1, which is enriched in neuronal primary cilia. To better understand the mechanism by which MCHR1 signaling affects olfactory behaviors we have first analyzed its distribution in the OB. Using antibody labeling, we find that MCHR1 localizes to cilia of interneurons in the granule cell and glomerular layers. To further confirm this, and generate a potential tool for future studies, we used CRISPR/CAS9 to fuse mCherry to the n‐terminus of MCHR1 (mCherry:MCHR1). Expression of mCherry:MCHR1 matches that of endogenous MCHR1, localizing to the primary cilium of granule cells and a subset of periglomerular cells. MCHR1, and mCherry:MCHR1, is not detected in the primary cilia of mitral cells, the primary output neurons of the olfactory bulb. To test the neuromodulatory role of MCHR1 in olfactory signaling, we have performed functional imaging experiments of the OB in response to odorant stimulation. Using epifluorescence calcium imaging, we find that glomerular responses of mitral/tufted cells are enhanced following administration of an MCHR1 antagonist, SNAP‐94847, (t(157) = 5.425, p &lt;0.0001) while application of MCH decreases glomerular responses (t(99) = 10.98, p &lt;0.0001). Together these data suggest that the ciliary GPCR, MCHR1 contributes to modulation of olfactory function. Furthermore, our newly generated mouse line will aid in studying the role of MCHR1 in other brain regions and will aid in determining the importance of ciliary localization of specific GPCRs in modulating neuronal function.Support or Funding InformationSupport was provided by R00DC013555 and pilot grans from the University of Florida Center for Smell and Taste, and a UF MBI pilot project (JCM), T32DC015994 (KRJ) F31DC 016485 (JMR) and R01DC004553 (RRR)

SPARC: Development of Pigs with mCherry‐CRE Recombinase Fusion Proteins in Cholinergic Neurons

Large animals are increasingly utilized in biomedical research and offer an advantage in that their anatomy and physiology closely parallel humans. Yet despite these advantages, rodent models dominate many areas of research, including neuroscience. This might be due in part to the greater number of technologies available to rodent researchers. Here we describe the development of pigs with mCherry and CRE‐recombinase proteins expressed in cholinergic neurons. We first cloned a 5,972 bp DNA fragment containing the predicted choline acetyltransferase (ChAT) promoter from porcine genomic DNA and placed into a pGlow TOPO™ TA expression system. We then tested for promoter activity by transfecting the expression system into porcine hippocampal slices and assessed for green fluorescent protein (GFP). We observed GFP at 60–72 hours post transfection. Confirmation of specificity was achieved by using antibody detection of ChAT. To optimize the expression system, we relied upon proven strategies used in rodents, and added an additional 535 bp of predicted promoter to the 5’ end. We then used this sequence to drive production of a mCherry‐P2A‐CRE recombinase fusion protein (ChAT‐mCherry‐P2A‐CRE). We transfected brain slice cultures from the pig hippocampus, striatum and brainstem with ChAT‐mCherry‐P2A‐CRE. Approximately 60 hours later, we isolated RNA and froze brain slices from transfected and non‐transfected samples. qRT‐PCR revealed mCherry and CRE recombinase mRNA in all transfected tissues. Expression of mCherry protein was also visible in discreet subsets of neurons in transfected samples. Studies are ongoing to confirm mCherry expression in cholinergic neurons. Key next steps include engineering our ChAT‐mCherry‐P2A‐CRE to contain GGTA1 homology arms for placement into the GGTA1 safe harbor in the pig genome, providing in vivo validation of ChAT‐mCherry‐P2A‐CRE using lentivirus pseudotyped with rabies glycoprotein, and targeting porcine fetal fibroblasts for somatic cell nuclear transfer. If successful, this model will allow for simultaneous visualization of neurons (and their innervation), and the ability to control or monitor neural activity through CRE‐mediated recombination.Support or Funding InformationHL119560, 1OT2OD026582

Construction of a RFP-lacZα bicistronic reporter system and its application in lead biosensing.

The combination of a fluorescent reporter and enzymatic reporter provides a flexible and versatile way for the study of diverse biological processes, such as the detection of transcription and translation. Thus, there is an urgent need to develop this novel bifunctional reporter system. This study reports the design, construction, and validation of a new dicistronic mCherry-lacZα reporter system by artificial lac operon and pbr operon models in lacZM15-producing E. coli. It allows two reporter genes to be co-transcribed into a dicistronic mRNA strand, followed by coupled expression of mCherry and lacZα. In artificial lac operons, expression of the downstream lacZα was demonstrated to be positively related to expression of the upstream ORF. In artificial pbr operons, compared with the insertion of downstream full-length lacZ, the insertion of downstream lacZα exerted a slight effect on the response from the upstream mCherry. Furthermore, the downstream lacZα reporter showed stronger response to Pb(II) than the downstream full-length lacZ. Importantly, the response sensitivity of downstream lacZα was still higher than that of upstream mCherry in a dual RFP-lacZα reporter construct. The highly efficient expression profile of the reporter lacZα peptide makes it a preferred downstream reporter in polycistronic constructs. This novel bifunctional reporter system offers a robust tool for biological studies.

Targeted viral vector transduction of relaxin-3 neurons in the rat nucleus incertus using a novel cell-type specific promoter

Modern neuroscience utilizes transgenic techniques extensively to study the activity and function of brain neural networks. A key feature of this approach is its compatibility with molecular methods for selective transgene expression in neuronal circuits of interest. Until now, such targeted transgenic approaches have not been applied to the extensive circuitry involving the neuropeptide, relaxin-3. Pharmacological and gene knock-out studies have revealed relaxin-3 signalling modulates interrelated behaviours and cognitive processes, including stress and anxiety, food and alcohol consumption, and spatial and social memory, highlighting the potential of this system as a therapeutic target. In the present study, we aimed to identify a promoter sequence capable of regulating cell-type specific transgene expression from an adeno-associated viral (AAV) vector in relaxin-3 neurons of the rat nucleus incertus (NI). In parallel to relaxin-3 promoter sequences, we also tested an AAV vector containing promoter elements for the tropomyosin receptor kinase A (TrkA) gene, as TrkA is co-expressed with relaxin-3 in rat NI neurons. Stereotaxic injection of an mCherry-expressing AAV vector revealed widespread non-specific TrkA promoter (880 bp) activity in and adjacent to the NI at 8 weeks post-treatment. In contrast, mCherry expression was successfully restricted to relaxin-3 NI neurons with 98% specificity using a 1736 bp relaxin-3 promoter. In addition to detailed anatomical mapping of NI relaxin-3 networks, illustrated here in association with GABAergic medial septum neurons, this method for targeted transgene delivery offers a versatile tool for ongoing preclinical studies of relaxin-3 circuitry.