Extraction of DNA from mouse tails

Role of the Beta and Gamma Isoforms of the Adapter Protein SH2B1 in Regulating Energy Balance

Human variants of the adapter protein SH2B1 are associated with severe childhood obesity, hyperphagia, and insulin resistance-phenotypes mimicked by mice lacking Sh2b1. SH2B1β and γ isoforms are expressed ubiquitously, whereas SH2B1α and δ isoforms are expressed primarily in the brain. Restoring SH2B1β driven by the neuron-specific enolase promoter largely reverses the metabolic phenotype of Sh2b1-null mice, suggesting crucial roles for neuronal SH2B1β in energy balance control. Here we test this hypothesis by using CRISPR/Cas9 gene editing to delete the β and γ isoforms from the neurons of mice (SH2B1βγ neuron-specific knockout [NKO] mice) or throughout the body (SH2B1βγ knockout [KO] mice). While parameters of energy balance were normal in both male and female SH2B1βγ NKO mice, food intake, body weight, and adiposity were increased in male (but not female) SH2B1βγ KO mice. Analysis of long-read single-cell RNA seq data from wild-type mouse brain revealed that neurons express almost exclusively the α and δ isoforms, whereas neuroglial cells express almost exclusively the β and γ isoforms. Our work suggests that neuronal SH2B1β and γ are not primary regulators of energy balance. Rather, non-neuronal SH2B1β and γ in combination with neuronal SH2B1α and δ suffice for body weight maintenance. While SH2B1β/γ and SH2B1α/δ share some functionality, SH2B1β/γ appears to play a larger role in promoting leanness.

A 5′ UTR Mutation Contributes to Down-Regulation of Bbs7 in the Berlin Fat Mouse

The Bardet–Biedl Syndrome 7 (Bbs7) gene was identified as the most likely candidate gene causing juvenile obesity in the Berlin Fat Mouse Inbred (BFMI) line. Bbs7 expression is significantly lower in the brain, adipose tissue, and liver of BFMI mice compared to lean C57BL/6NCrl (B6N) mice. A DNA sequence comparison between BFMI and B6N revealed 16 sequence variants in the Bbs7 promoter region. Here, we tested if these mutations contribute to the observed differential expression of Bbs7. In a cell-based dual-luciferase assay, we compared the effects of the BFMI and the B6N haplotypes of different regions of the Bbs7 promotor on the reporter gene expression. A single-nucleotide polymorphism (SNP) was identified causing a significant reduction in the reporter gene expression. This SNP (rs29947545) is located in the 5′ UTR of Bbs7 at Chr3:36.613.350. The SNP is not unique to BFMI mice but also occurs in several other mouse strains, where the BFMI allele is not associated with lower Bbs7 transcript amounts. Thus, we suggest a compensatory mutation in the other mouse strains that keeps Bbs7 expression at the normal level. This compensatory mechanism is missing in BFMI mice and the cell lines tested.

BMP3 Affects Cortical and Trabecular Long Bone Development in Mice

Bone morphogenetic proteins (BMPs) have a major role in tissue development. BMP3 is synthesized in osteocytes and mature osteoblasts and has an antagonistic effect on other BMPs in bone tissue. The main aim of this study was to fully characterize cortical bone and trabecular bone of long bones in both male and female Bmp3^−/− mice. To investigate the effect of Bmp3 from birth to maturity, we compared Bmp3^−/− mice with wild-type littermates at the following stages of postnatal development: 1 day (P0), 2 weeks (P14), 8 weeks and 16 weeks of age. Bmp3 deletion was confirmed using X-gal staining in P0 animals. Cartilage and bone tissue were examined in P14 animals using Alcian Blue/Alizarin Red staining. Detailed long bone analysis was performed in 8-week-old and 16-week-old animals using micro-CT. The Bmp3 reporter signal was localized in bone tissue, hair follicles, and lungs. Bone mineralization at 2 weeks of age was increased in long bones of Bmp3^−/− mice. Bmp3 deletion was shown to affect the skeleton until adulthood, where increased cortical and trabecular bone parameters were found in young and adult mice of both sexes, while delayed mineralization of the epiphyseal growth plate was found in adult Bmp3^−/− mice.

Adenylyl cyclase 3 deficiency results in dysfunction of blood-testis barrier during mouse spermiogenesis

Human infertility has become a global medical and social health problem. Mice deficient in type 3 adenylyl cyclase (AC3), a key enzyme that synthesizes cyclic adenosine monophosphate (cAMP), develop male infertility, although the underlying molecular mechanisms remain unknown. We performed a label-free quantitative (LFQ) proteomics analyses to identify testicular differentially expressed proteins (DEPs) and their respective biological processes. Furthermore, histological examination demonstrated that AC3 deficiency in mice led to mild impairment of spermatogenesis, including the thinning of seminiferous epithelium and local lesions in the testis. We further identified that the integrity of the blood-testis barrier (BTB) was impaired in AC3 knockout (AC3^-/-) mice accompanied with the reduction in the expression of tight junctions (TJs) and ectoplasmic specialization (ESs)-related proteins. In addition, the deletion of AC3 in mice also reduced the germ cell proliferation, increased apoptosis, and decreased lipid deposition in the seminiferous tubules. Collectively, our results revealed a role of AC3 in regulating the BTB integrity during spermatogenesis. Thus, our findings provide new perspectives for future research in male infertility.

Broad spectrum of CRISPR-induced edits in an embryonic lethal gene

Mendelian genetics poses practical limitations on the number of mutant genes that can be investigated simultaneously for their roles in embryonic development in the mouse. While CRISPR-based gene editing of multiple genes at once offers an attractive alternative strategy, subsequent breeding or establishment of permanent mouse lines will rapidly segregate the different mutant loci again. Direct phenotypic analysis of genomic edits in an embryonic lethal gene in F0 generation mice, or F0 mouse embryos, circumvents the need for breeding or establishment of mutant mouse lines. In the course of genotyping a large cohort of F0 CRISPants, where the embryonic lethal gene T/brachyury was targeted, we noted the presence of multiple CRISPR-induced modifications in individual embryos. Using long-read single-molecule Nanopore sequencing, we identified a wide variety of deletions, ranging up to 3 kb, that would not have been detected or scored as wildtype with commonly used genotyping methods that rely on subcloning and short-read or Sanger sequencing. Long-read sequencing results were crucial for accurate genotype-phenotype correlation in our F0 CRISPants. We thus demonstrate feasibility of screening manipulated F0 embryos for mid-gestation phenotypic consequences of CRISPR-induced mutations without requiring derivation of permanent mouse lines.

The type 3 adenylyl cyclase is crucial for intestinal mucosal neural network in the gut lamina propria

BACKGROUND

The type 3 adenylyl cyclase (AC3) enzyme is involved in the synthesis of cyclic adenosine monophosphate (cAMP). It is primarily expressed in the central nervous system (CNS) and plays a crucial role in neurogenesis and neural dendritic arborization. However, the AC3's functional role in the gastrointestinal tract remains ambiguous.

METHODS

AC3 expression in enteric tissue of AC3^+/+ mice was investigated using immunohistochemistry and RT-PCR. AC3 knock-out mice (AC3^-/- ) were used to examine the effect of AC3 on the enteric nervous system (ENS) function and the number of cilia and apoptotic cells. Additionally, total gastrointestinal transit time and colonic motility were compared between the AC3^-/- and AC3^+/+ groups of mice.

KEY RESULTS

AC3 was predominately expressed in the myenteric plexus of the large intestine. Colonic-bead expulsion analysis showed accelerated propulsion in the large intestine of the AC3^-/- mice. The AC3^-/- mice demonstrated reduced nerve fibers and enteric glial cells count in colonic mucosa compared to the AC3^+/+ mice. Furthermore, AC3^-/- mice exhibited increased cellular apoptosis and reduced ARL13B⁺ cilium cells in the colonic lamina propria compared to the AC3^+/+ mice.

CONCLUSIONS

In AC3^-/- mice, innervation of the lamina propria in the colonic mucosa was reduced and colonic propulsion was accelerated. AC3 is crucial for the development and function of the adult neural network of ENS. AC3 deficiency caused atrophy in the colonic mucosal neural network of mice.

Mitochondrial Genome Evolution, Genetic Diversity, and Population Structure in British Water Voles (Arvicola amphibius)

The European water vole (Arvicola amphibius) is a rodent within the subfamily Arvicolinae. In Britain, water voles have declined rapidly during the last century, making them a conservation priority. The relationship of Arvicola to other genera within Arvicolinae remains debated. Additionally, the impact that captive breeding programs in Britain are having on the genetic diversity of water voles is unknown. We use available mitochondrial genomes to construct the phylogeny of species within Arvicolinae, followed by sequencing the mitochondrial DNA control region of 17 individuals from a captive population of water voles in Britain to assess their genetic diversity and population structure. Our study first provides an updated phylogenetic tree of Arvicolinae using the mitochondrial genome of 31 species. Second, our results show considerable genetic diversity in the captive population of water voles, when compared with natural populations in Britain. We confirm the grouping of British water voles into two clades, with all captive individuals found in the English/Welsh clade. Moreover, captive water voles clustered closely with populations in the South East and East of England. The mitochondrial genome provides a useful marker to study the phylogenetics of this rodent clade and in addition, our study provides support for the breeding program at Wildwood Trust and provides a framework for future conservation genetics studies in this species.

Differential requirements for MDM2 E3 activity during embryogenesis and in adult mice

The p53 tumor suppressor protein is a potent activator of proliferative arrest and cell death. In normal cells, this pathway is restrained by p53 protein degradation mediated by the E3-ubiquitin ligase activity of MDM2. Oncogenic stress releases p53 from MDM2 control, so activating the p53 response. However, many tumors that retain wild-type p53 inappropriately maintain the MDM2-p53 regulatory loop in order to continuously suppress p53 activity. We have shown previously that single point mutations in the human MDM2 RING finger domain prevent the interaction of MDM2 with the E2/ubiquitin complex, resulting in the loss of MDM2's E3 activity without preventing p53 binding. Here, we show that an analogous mouse MDM2 mutant (MDM2 I438K) restrains p53 sufficiently for normal growth but exhibits an enhanced stress response in vitro. In vivo, constitutive expression of MDM2 I438K leads to embryonic lethality that is rescued by p53 deletion, suggesting MDM2 I438K is not able to adequately control p53 function through development. However, the switch to I438K expression is tolerated in adult mice, sparing normal cells but allowing for an enhanced p53 response to DNA damage. Viewed as a proof of principle model for therapeutic development, our findings support an approach that would inhibit MDM2 E3 activity without preventing MDM2/p53 binding as a promising avenue for development of compounds to activate p53 in tumors with reduced on-target toxicities.

Temporal-specific roles of fragile X mental retardation protein in the development of the hindbrain auditory circuit

Fragile X mental retardation protein (FMRP) is an RNA-binding protein abundant in the nervous system. Functional loss of FMRP leads to sensory dysfunction and severe intellectual disabilities. In the auditory system, FMRP deficiency alters neuronal function and synaptic connectivity and results in perturbed processing of sound information. Nevertheless, roles of FMRP in embryonic development of the auditory hindbrain have not been identified. Here, we developed high-specificity approaches to genetically track and manipulate throughout development of the Atoh1⁺ neuronal cell type, which is highly conserved in vertebrates, in the cochlear nucleus of chicken embryos. We identified distinct FMRP-containing granules in the growing axons of Atoh1⁺ neurons and post-migrating NM cells. FMRP downregulation induced by CRISPR/Cas9 and shRNA techniques resulted in perturbed axonal pathfinding, delay in midline crossing, excess branching of neurites, and axonal targeting errors during the period of circuit development. Together, these results provide the first in vivo identification of FMRP localization and actions in developing axons of auditory neurons, and demonstrate the importance of investigating early embryonic alterations toward understanding the pathogenesis of neurodevelopmental disorders.

The microRNA/TET3/REST axis is required for olfactory globose basal cell proliferation and male behavior

In the main olfactory epithelium (MOE), new olfactory sensory neurons (OSNs) are persistently generated to replace lost neurons throughout an organism's lifespan. This process predominantly depends on the proliferation of globose basal cells (GBCs), the actively dividing stem cells in the MOE. Here, by using CRISPR/Cas9 and RNAi coupled with adeno-associated virus (AAV) nose delivery approaches, we demonstrated that knockdown of miR-200b/a in the MOE resulted in supernumerary Mash1-marked GBCs and decreased numbers of differentiated OSNs, accompanied by abrogation of male behaviors. We further showed that in the MOE, miR-200b/a targets the ten-eleven translocation methylcytosine dioxygenase TET3, which cooperates with RE1-silencing transcription factor (REST) to exert their functions. Deficiencies including proliferation, differentiation, and behaviors illustrated in miR-200b/a knockdown mice were rescued by suppressing either TET3 or REST. Our work describes a mechanism of coordination of GBC proliferation and differentiation in the MOE and olfactory male behaviors through miR-200/TET3/REST signaling.

Type 3 adenylyl cyclase in the main olfactory epithelium participates in depression-like and anxiety-like behaviours

BACKGROUND

Deficiency of olfaction is thought to be associated with depression, and type 3 adenylyl cyclase (AC₃) genetic knockout and forebrain knockout mice show depression-like behaviours. AC₃ is expressed in the main olfactory epithelium (MOE) and hippocampus, which plays an important role in olfactory signal transduction. However, it is unclear whether AC₃ in the MOE also plays a role in the pathogenesis of depression. Thus, we aimed to study the relationship between AC₃ in the MOE and the pathogenesis of depression.

METHODS

We obtained anosmic mice by intranasal perfusion of zinc sulphate (ZnSO₄) (ZnSO₄ mice), and distinctively knocked down AC₃ in the MOE (AC_3KD/MOE mice) by CRISPR/cas9 technology. Behavioural tests related to depression and anxiety were employed to evaluate the depression- and anxiety-like behaviours of mice. The mRNA and protein expressions of tyrosine hydroxylase (TH), dopamine receptors (Drds), and N-Methyl D-aspartate receptor subunit 2B (GluN2B) in the hippocampus of mice were investigated by qPCR and western blotting to explore the mechanism of depression and anxiety caused by AC₃ in the MOE, preliminarily.

RESULTS

Compared with NaCl mice, ZnSO₄ mice exhibited depression-like behaviours in tail suspension tests (TST), forced swimming tests, and social (FST) interaction tests (SIT), but showed no anxiety-like behaviours in anxiety-related behavioural tests. The mRNA and protein expressions of Drd3 and GluN2B in the hippocampus of ZnSO₄ mice were significantly downregulated. Compared with the negative control mice (NC mice), AC_{3KD / MOE} mice showed depression-like behaviours in TST, FST, and SIT tests, anxiety-like behaviours in light/dark transition test, elevated-plus maze test, and novelty-suppressed feeding test. The protein expressions of Drd3, TH, and GluN2B were significantly downregulated in the hippocampus.

LIMITATIONS

We did not further demonstrate that AC₃ in the MOE causes depression through the dopaminergic nervous system with dopamine or dopamine receptor agonists.

CONCLUSIONS

Our data demonstrate that intranasal infusion of ZnSO₄ can cause depression-like behaviours and has no effect on anxiety-like behaviours. Specific knockdown of AC₃ in the MOE can cause depression-like and anxiety-like behaviours. The behavioural changes caused by intranasal ZnSO₄ and specific knockdown of AC₃ in the MOE can be related to the significant downregulation of dopaminergic system and GluN2B expressions in the hippocampus of mice.

Hindgut microbiota in laboratory-reared and wild Triatoma infestans

Triatomine vectors transmit Trypanosoma cruzi, the etiological agent of Chagas disease in humans. Transmission to humans typically occurs when contaminated triatomine feces come in contact with the bite site or mucosal membranes. In the Southern Cone of South America, where the highest burden of disease exists, Triatoma infestans is the principal vector for T. cruzi. Recent studies of other vector-borne illnesses have shown that arthropod microbiota influences the ability of infectious agents to colonize the insect vector and transmit to the human host. This has garnered attention as a potential control strategy against T. cruzi, as vector control is the main tool of Chagas disease prevention. Here we characterized the microbiota in T. infestans feces of both wild-caught and laboratory-reared insects and examined the relationship between microbial composition and T. cruzi infection using highly sensitive high-throughput sequencing technology to sequence the V3-V4 region of the 16S ribosomal RNA gene on the MiSeq Illumina platform. We collected 59 wild (9 with T. cruzi infection) and 10 lab-reared T. infestans (4 with T. cruzi infection) from the endemic area of Arequipa, Perú. Wild T. infestans had greater hindgut bacterial diversity than laboratory-reared bugs. Microbiota of lab insects comprised a subset of those identified in their wild counterparts, with 96 of the total 124 genera also observed in laboratory-reared insects. Among wild insects, variation in bacterial composition was observed, but time and location of collection and development stage did not explain this variation. T. cruzi infection in lab insects did not affect α- or β-diversity; however, we did find that the β-diversity of wild insects differed if they were infected with T. cruzi and identified 10 specific taxa that had significantly different relative abundances in infected vs. uninfected wild T. infestans (Bosea, Mesorhizobium, Dietzia, and Cupriavidus were underrepresented in infected bugs; Sporosarcina, an unclassified genus of Porphyromonadaceae, Nestenrenkonia, Alkalibacterium, Peptoniphilus, Marinilactibacillus were overrepresented in infected bugs). Our findings suggest that T. cruzi infection is associated with the microbiota of T. infestans and that inferring the microbiota of wild T. infestans may not be possible through sampling of T. infestans reared in the insectary.

Chagas disease in humans is caused by the parasite Trypanosoma cruzi and it is endemic to the Americas. Poor populations are most at risk. The parasite infects an estimated six million people of 21 endemic countries in the Americas, with 30,000 new infections yearly. The main mode of transmission is vector-borne by triatomine bugs, which tend to live in close association with humans. The main Chagas disease vector in the Southern Cone of South America, where the highest burden of disease exists, is Triatoma infestans. As blood-sucking insects, triatomines become infected when they bite a T. cruzi-positive human and once infected they transmit the parasites in their feces. Controlling the vector populations is the main strategy of Chagas disease transmission reduction efforts. Microbiota-mediated methods to control this vector-borne disease are now being explored to determine whether microbes typically found in the vectors’ gut have a detrimental effect on T. cruzi and how they may be used to modify the vector and curb the ability for T. cruzi to be transmitted to humans. To advance this new field, we first must gain better knowledge of the gut microbiota of triatomines. Our study is the first to use sensitive high-throughput methods to study the gut microbes of T. infestans, using both laboratory-reared and wild insects. We have found that the microbial composition of T. infestans in the laboratory does not reflect the complete collection of gut microbes of wild T. infestans and inferring the gut microbiota profile of wild insects through studying lab insects alone may not be possible. We also found evidence that in wild insects T. cruzi affects the composition of the gut microbiota and identified some bacterial taxa which may be important in modulating the T.infestans-T.cruzi relationship.

BBS4 is required for intraflagellar transport coordination and basal body number in mammalian olfactory cilia

Bardet-Beidl syndrome (BBS) manifests from genetic mutations encoding for one or more BBS proteins. BBS4 loss impacts olfactory ciliation and odor detection, yet the cellular mechanisms remain unclear. Here, we report that Bbs4-/- mice exhibit shorter and fewer olfactory sensory neuron (OSN) cilia despite retaining odorant receptor localization. Within Bbs4-/- OSN cilia, we observed asynchronous rates of IFT-A/B particle movements, indicating miscoordination in IFT complex trafficking. Within the OSN dendritic knob, the basal bodies are dynamic, with incorporation of ectopically expressed centrin-2 and γ-tubulin occurring after nascent ciliogenesis. Importantly, BBS4 loss results in the reduction of basal body numbers separate from cilia loss. Adenoviral expression of BBS4 restored OSN cilia lengths and was sufficient to re-establish odor detection, but failed to rescue ciliary and basal body numbers. Our results yield a model for the plurality of BBS4 functions in OSNs that includes intraciliary and periciliary roles that can explain the loss of cilia and penetrance of ciliopathy phenotypes in olfactory neurons.

Efficient mouse genome engineering by CRISPR-EZ technology

CRISPR/Cas9 technology has transformed mouse genome editing with unprecedented precision, efficiency, and ease; however, the current practice of microinjecting CRISPR reagents into pronuclear-stage embryos remains rate-limiting. We thus developed CRISPR ribonucleoprotein (RNP) electroporation of zygotes (CRISPR-EZ), an electroporation-based technology that outperforms pronuclear and cytoplasmic microinjection in efficiency, simplicity, cost, and throughput. In C57BL/6J and C57BL/6N mouse strains, CRISPR-EZ achieves 100% delivery of Cas9/single-guide RNA (sgRNA) RNPs, facilitating indel mutations (insertions or deletions), exon deletions, point mutations, and small insertions. In a side-by-side comparison in the high-throughput KnockOut Mouse Project (KOMP) pipeline, CRISPR-EZ consistently outperformed microinjection. Here, we provide an optimized protocol covering sgRNA synthesis, embryo collection, RNP electroporation, mouse generation, and genotyping strategies. Using CRISPR-EZ, a graduate-level researcher with basic embryo-manipulation skills can obtain genetically modified mice in 6 weeks. Altogether, CRISPR-EZ is a simple, economic, efficient, and high-throughput technology that is potentially applicable to other mammalian species.

Metabolic, Epigenetic, and Transgenerational Effects of Gut Bacterial Choline Consumption

Choline is an essential nutrient and methyl donor required for epigenetic regulation. Here, we assessed the impact of gut microbial choline metabolism on bacterial fitness and host biology by engineering a microbial community that lacks a single choline-utilizing enzyme. Our results indicate that choline-utilizing bacteria compete with the host for this nutrient, significantly impacting plasma and hepatic levels of methyl-donor metabolites and recapitulating biochemical signatures of choline deficiency. Mice harboring high levels of choline-consuming bacteria showed increased susceptibility to metabolic disease in the context of a high-fat diet. Furthermore, bacterially induced reduction of methyl-donor availability influenced global DNA methylation patterns in both adult mice and their offspring and engendered behavioral alterations. Our results reveal an underappreciated effect of bacterial choline metabolism on host metabolism, epigenetics, and behavior. This work suggests that interpersonal differences in microbial metabolism should be considered when determining optimal nutrient intake requirements.

Differentially expressed genes in the testicular tissues of adenylyl cyclase 3 knockout mice

Adenylate cyclase 3 (AC3) is an important component of the cyclic adenosine 3',5'-monophosphate (cAMP) signaling pathway and converts adenosine triphosphate into cAMP. Male mice with AC3 deletion (AC3^-/-) are sterile. However, the mechanical mechanism remains unclear. By TUNEL staining, we found that cell apoptosis in the testicular tissues of AC3^-/- mice increased significantly compared with that in the wild-type (AC3^+/+) mice. Differentially expressed genes regulated by AC3 in the testicular tissues were identified by gene chip hybridization. We observed that the expression of 693 genes was altered in the testicular tissues of AC3^-/- mice, including 330 up-regulated and 363 down-regulated gene expression with fold changes higher than 2 (≥2) as the standards. Furthermore, part of these differentially expressed genes was verified by the real-time fluorescence quantification PCR and immunofluorescent staining. The expression levels of the genes related to olfactory receptors, cell apoptosis, transcriptional activity, defensive reaction, cell adhesion, cell death, and immunoreactions were significantly altered in the testicular tissues of AC3^-/- mice compared with AC3^+/+ mice. In addition, the corresponding Ca²⁺, cAMP, and cell adhesion signaling pathways, as well as the signaling pathways related to axon guidance and cell interaction, were altered significantly in the AC3^-/- mice. These data would help elucidate the general understanding of the mechanisms underlying the sterility in AC3^-/- male mice.

Deletion of Type 3 Adenylyl Cyclase Perturbs the Postnatal Maturation of Olfactory Sensory Neurons and Olfactory Cilium Ultrastructure in Mice

Type 3 adenylyl cyclase (Adcy3) is localized to the cilia of olfactory sensory neurons (OSNs) and is an essential component of the olfactory cyclic adenosine monophosphate (cAMP) signaling pathway. Although the role of this enzyme in odor detection and axonal projection in OSNs was previously characterized, researchers will still have to determine its function in the maturation of postnatal OSNs and olfactory cilium ultrastructure. Previous studies on newborns showed that the anatomic structure of the main olfactory epithelium (MOE) of Adcy3 knockout mice (Adcy3^-/-) is indistinguishable from that of their wild-type littermates (Adcy3^+/+), whereas the architecture and associated composition of MOE are relatively underdeveloped at this early age. The full effects of sensory deprivation on OSNs may not also be exhibited in such age. In the present study, following a comparison of postnatal OSNs in seven-, 30-, and 90-day-old Adcy3^-/- mice and wild-type controls (Adcy3^+/+), we observed that the absence of Adcy3 leads to cumulative defects in the maturation of OSNs. Upon aging, Adcy3^-/- OSNs exhibited increase in immature cells and reduction in mature cells along with elevated apoptosis levels. The density and ultrastructure of Adcy3^-/- cilia were also disrupted in mice upon aging. Collectively, our results reveal an indispensable role of Adcy3 in postnatal maturation of OSNs and maintenance of olfactory cilium ultrastructure in mice through adulthood.

Modulation of p38 kinase by DUSP4 is important in regulating cardiovascular function under oxidative stress

Over-activation of p38 is implicated in many cardiovascular diseases (CVDs), including myocardial infarction, hypertrophy, heart failure, and ischemic heart disease. Numerous therapeutic interventions for CVDs have been directed toward the inhibition of the p38 mitogen-activated protein kinase activation that contributes to the detrimental effect after ischemia/reperfusion (I/R) injuries. However, the efficacy of these treatments is far from ideal, as they lack specificity and are associated with high toxicity. Previously, we demonstrated that N-acetyl cysteine (NAC) pretreatment up-regulates DUSP4 expression in endothelial cells, regulating p38 and ERK1/2 activities, and thus providing a protective effect against oxidative stress. Here, endothelial cells under hypoxia/reoxygenation (H/R) insult and isolated heart I/R injury were used to investigate the role of DUSP4 in the modulation of the p38 pathway. In rat endothelial cells, DUSP4 is time-dependently degraded by H/R (0.25 ± 0.07-fold change of control after 2h H/R). Its degradation is closely associated with hyperphosphorylation of p38 (2.1 ± 0.36-fold change) and cell apoptosis, as indicated by the increase in cells immunopositive for cleaved caspase-3 (12.59 ± 3.38%) or TUNEL labeling (29.46 ± 3.75%). The inhibition of p38 kinase activity with 20 µM SB203580 during H/R prevents H/R-induced apoptosis, assessed via TUNEL (12.99 ± 1.89%). Conversely, DUSP4 gene silencing in endothelial cells augments their sensitivity to H/R-induced apoptosis (45.81 ± 5.23%). This sensitivity is diminished via the inhibition of p38 activity (total apoptotic cells drop to 17.47 ± 1.45%). Interestingly, DUSP4 gene silencing contributes to the increase in superoxide generation from cells. Isolated Langendorff-perfused mouse hearts were subjected to global I/R injury. DUSP4(-/-) hearts had significantly larger infarct size than WT. The increase in I/R-induced infarct in DUSP4(-/-) mice significantly correlates with reduced functional recovery (assessed by RPP%, LVDP%, HR%, and dP/dtmax) as well as lower CF% and a higher initial LVEDP. From immunoblotting analysis, it is evident that p38 is significantly overactivated in DUSP4(-/-) mice after I/R injury. The activation of cleaved caspase-3 is seen in both WT and DUSP4(-/-) I/R hearts. Infusion of a p38 inhibitor prior to ischemia and during the reperfusion improves both WT and DUSP4(-/-) cardiac function. Therefore, the identification of p38 kinase modulation by DUSP4 provides a novel therapeutic target for oxidant-induced diseases, especially myocardial infarction.

Gene Expression Profiles of Main Olfactory Epithelium in Adenylyl Cyclase 3 Knockout Mice

Adenylyl Cyclase 3 (AC3) plays an important role in the olfactory sensation-signaling pathway in mice. AC3 deficiency leads to defects in olfaction. However, it is still unknown whether AC3 deficiency affects gene expression or olfactory signal transduction pathways within the main olfactory epithelium (MOE). In this study, gene microarrays were used to screen differentially expressed genes in MOE from AC3 knockout (AC3^−/−) and wild-type (AC3^+/+) mice. The differentially expressed genes identified were subjected to bioinformatic analysis and verified by qRT-PCR. Gene expression in the MOE from AC3^−/− mice was significantly altered, compared to AC3^+/+ mice. Of the 41266 gene probes, 3379 had greater than 2-fold fold change in expression levels between AC3^−/− and AC3^+/+ mice, accounting for 8% of the total gene probes. Of these genes, 1391 were up regulated, and 1988 were down regulated, including 425 olfactory receptor genes, 99 genes that are specifically expressed in the immature olfactory neurons, 305 genes that are specifically expressed in the mature olfactory neurons, and 155 genes that are involved in epigenetic regulation. Quantitative RT-PCR verification of the differentially expressed epigenetic regulation related genes, olfactory receptors, ion transporter related genes, neuron development and differentiation related genes, lipid metabolism and membrane protein transport etc. related genes showed that P75NTR, Hinfp, Gadd45b, and Tet3 were significantly up-regulated, while Olfr370, Olfr1414, Olfr1208, Golf, Faim2, Tsg101, Mapk10, Actl6b, H2BE, ATF5, Kirrrel2, OMP, Drd2etc. were significantly down-regulated. In summary, AC3 may play a role in proximal olfactory signaling and play a role in the regulation of differentially expressed genes in mouse MOE.

Genomic alterations in abnormal neutrophils isolated from adult patients with systemic lupus erythematosus

INTRODUCTION

Patients with systemic lupus erythematosus (SLE) have an abnormal population of neutrophils, called low-density granulocytes (LDGs), that express the surface markers of mature neutrophils, yet their nuclear morphology resembles an immature cell. Because a similar discrepancy in maturation status is observed in myelodysplasias, and disruption of neutrophil development is frequently associated with genomic alterations, genomic DNA isolated from autologous pairs of LDGs and normal-density neutrophils was compared for genomic changes.

METHODS

Alterations in copy number and losses of heterozygosity (LOH) were detected by cytogenetic microarray analysis. Microsatellite instability (MSI) was detected by capillary gel electrophoresis of fluorescently labeled PCR products.

RESULTS

Control neutrophils and normal-density SLE neutrophils had similar levels of copy number variations, while the autologous SLE LDGs had an over twofold greater number of copy number alterations per genome. The additional copy number alterations found in LDGs were prevalent in six of the thirteen SLE patients, and occurred preferentially on chromosome 19, 17, 8, and X. These same SLE patients also displayed an increase in LOH. Several SLE patients had a common LOH on chromosome 5q that includes several cytokine genes and a DNA repair enzyme. In addition, three SLE patients displayed MSI. Two patients displayed MSI in greater than one marker, and one patient had MSI and increased copy number alterations. No correlations between genomic instability and immunosuppressive drugs, disease activity or disease manifestations were apparent.

CONCLUSIONS

The increased level of copy number alterations and LOH in the LDG samples relative to autologous normal-density SLE neutrophils suggests somatic alterations that are consistent with DNA strand break repair, while MSI suggests a replication error-prone status. Thus, the LDGs isolated have elevated levels of somatic alterations that are consistent with genetic damage or genomic instability. This suggests that the LDGs in adult SLE patients are derived from cell progenitors that are distinct from the autologous normal-density neutrophils, and may reflect a role for genomic instability in the disease.

Discoidin domain receptor 2 germline gene deletion leads to altered heart structure and function in the mouse

Discoidin domain receptor 2 (DDR2) is a fibrillar collagen receptor that is expressed in mesenchymal cells throughout the body. In the heart, DDR2 is selectively expressed on cardiac fibroblasts. We generated a germline DDR2 knockout mouse and used this mouse to examine the role of DDR2 deletion on heart structure and function. Echocardiographic measurements from null mice were consistent with those from a smaller heart, with reduced left ventricular chamber dimensions and little change in wall thickness. Fractional shortening appeared normal. Left ventricular pressure measurements revealed mild inotropic and lusitropic abnormalities that were accentuated by dobutamine infusion. Both body and heart weights from 10-wk-old male mice were ~20% smaller in null mice. The reduced heart size was not simply due to reduced body weight, since cardiomyocyte lengths were atypically shorter in null mice. Although normalized cardiac collagen mass (assayed by hydroxyproline content) was not different in null mice, the collagen area fraction was statistically higher, suggesting a reduced collagen density from altered collagen deposition and cross-linking. Cultured cardiac fibroblasts from null mice deposited collagen at a slower rate than wild-type littermates, possibly due to the expression of lower prolyl 4-hydroxylase α-isoform 1 enzyme levels. We conclude that genetic deletion of the DDR2 collagen receptor alters cardiac fibroblast function. The resulting perturbations in collagen deposition can influence the structure and function of mature cardiomyocytes.

Completely humanizing prolactin rescues infertility in prolactin knockout mice and leads to human prolactin expression in extrapituitary mouse tissues

A variety of fundamental differences have evolved in the physiology of the human and rodent prolactin (PRL) systems. The PRL gene in humans and other primates contains an alternative promoter, 5.8 kbp upstream of the pituitary transcription start site, which drives expression of PRL in "extrapituitary" tissues, where PRL is believed to exert local, or paracrine, actions. Several of these extrapituitary PRL tissues serve a reproductive function (eg, mammary gland, decidua, prostate, etc), consistent with the hypothesis that local PRL production may be involved in, and required for, normal reproductive physiology in primates. Rodent research models have generated significant findings regarding the role of PRL in reproduction. Specifically, disruption (knockout) of either the PRL gene or its receptor causes profound female reproductive defects at several levels (ovaries, preimplantation endometrium, mammary glands). However, the rodent PRL gene differs significantly from the human, most notably lacking the alternative promoter. Understanding of the physiological regulation and function of extrapituitary PRL has been limited by the absence of a readily accessible experimental model, because the rodent PRL gene does not contain the alternative promoter. To overcome these limitations, we have generated mice that have been "humanized" with regard to the structural gene and tissue expression of PRL. Here, we present the characterization of these animals, demonstrating that the human PRL transgene is responsive to known physiological regulators both in vitro and in vivo. More importantly, the expression of the human PRL transgene is able to rescue the reproductive defects observed in mouse PRL knockout (mPRL(-)) females, validating their usefulness in studying the function or regulation of this hormone in a manner that is relevant to human physiology.

Genotyping of plant and animal samples without prior DNA purification

The Direct PCR approach facilitates PCR amplification directly from small amounts of unpurified samples, and is demonstrated here for several plant and animal tissues (Figure 1). Direct PCR is based on specially engineered Thermo Scientific Phusion and Phire DNA Polymerases, which include a double-stranded DNA binding domain that gives them unique properties such as high tolerance of inhibitors. PCR-based target DNA detection has numerous applications in plant research, including plant genotype analysis and verification of transgenes. PCR from plant tissues traditionally involves an initial DNA isolation step, which may require expensive or toxic reagents. The process is time consuming and increases the risk of cross contamination. Conversely, by using Thermo Scientific Phire Plant Direct PCR Kit the target DNA can be easily detected, without prior DNA extraction. In the model demonstrated here, an example of derived cleaved amplified polymorphic sequence analysis (dCAPS) is performed directly from Arabidopsis plant leaves. dCAPS genotyping assays can be used to identify single nucleotide polymorphisms (SNPs) by SNP allele-specific restriction endonuclease digestion. Some plant samples tend to be more challenging when using Direct PCR methods as they contain components that interfere with PCR, such as phenolic compounds. In these cases, an additional step to remove the compounds is traditionally required. Here, this problem is overcome by using a quick and easy dilution protocol followed by Direct PCR amplification (Figure 1). Fifteen year-old oak leaves are used as a model for challenging plants as the specimen contains high amounts of phenolic compounds including tannins. Gene transfer into mice is broadly used to study the roles of genes in development, physiology and human disease. The use of these animals requires screening for the presence of the transgene, usually with PCR. Traditionally, this involves a time consuming DNA isolation step, during which DNA for PCR analysis is purified from ear, tail or toe tissues. However, with the Thermo Scientific Phire Animal Tissue Direct PCR Kit transgenic mice can be genotyped without prior DNA purification. In this protocol transgenic mouse genotyping is achieved directly from mouse ear tissues, as demonstrated here for a challenging example where only one primer set is used for amplification of two fragments differing greatly in size.

Modulation of androgens in southern hemisphere temperate breeding sparrows (Zonotrichia capensis): an altitudinal comparison

Most work investigating modulation of testosterone (T) levels in birds has focused on northern temperate and Arctic species, and to a lesser degree, tropical species. Studies exploring modulation of T in birds in temperate regions of the Southern Hemisphere are lacking. Here we explore patterns of T secretion across the breeding season in two populations of temperate Zonotrichia capensis in Chile, located only 130 km apart, but separated by 2000 m in elevation. We then compared these T profiles to those of conspecifcs in the tropics and congeners in northern zones. We measured baseline T levels during pre-breeding in lowland Z. c. chilensis, early breeding in highland Z. c. chilensis and mid-breeding in both populations. We also tested for social stimulation of T secretion during mid-breeding in both populations. Lastly, we challenged the hypothalamic-pituitary-gonadal (HPG) axis of the lowland population with gonadotropin-releasing hormone (GnRH) to determine maximum possible T production. We found that the highland population adjusted T secretion across the breeding season like northern species. Neither Z. c. chilensis population modulated T in response to social stimuli, nor the HPG axis of the lowland population was not maximally active during either pre- or mid-breeding. These results suggest that patterns of circulating T in the highland population of Z. c. chilensis in the Southern Hemisphere are similar to congeners in the temperate Northern Hemisphere, but those of the lowland population of Z. c. chilensis are not, and are more similar to conspecifics breeding in the tropics.

CXCR4 peptide antagonist inhibits primary breast tumor growth, metastasis and enhances the efficacy of anti-VEGF treatment or docetaxel in a transgenic mouse model

CXCR4 is a chemokine receptor implicated in the homing of cancer cells to target metastatic organs, which overexpress its ligand, stromal cell-derived factor (SDF)-1. To determine the efficacy of targeting CXCR4 on primary tumor growth and metastasis, we used a peptide inhibitor of CXCR4, CTCE-9908, that was administered in a clinically relevant approach using a transgenic breast cancer mouse model. We first performed a dosing experiment of CTCE-9908 in the PyMT mouse model, testing 25, 50 and 100 mg/kg versus the scrambled peptide in groups of 8-16 mice. We then combined CTCE-9908 with docetaxel or DC101 (an anti-VEGFR2 monoclonal antibody). We found that increasing doses of CTCE-9908 alone slowed the rate of tumor growth, with a 45% inhibition of primary tumor growth at 3.5 weeks of treatment with 50 mg/kg of CTCE-9908 (p = 0.005). Expression levels of VEGF were also found to be reduced by 42% with CTCE-9908 (p = 0.01). In combination with docetaxel, CTCE-9908 administration decreased tumor volume by 38% (p = 0.02), an effect that was greater than that observed with docetaxel alone. In combination with DC101, CTCE-9908 also demonstrated an enhanced effect compared to DC101 alone, with a 37% decrease in primary tumor volume (p = 0.01) and a 75% reduction in distant metastasis (p = 0.009). In combination with docetaxel or an anti-angiogenic agent, the anti-tumor and anti-metastatic effects of CTCE-9908 were markedly enhanced, suggesting potentially new effective combinatorial therapeutic strategies in the treatment of breast cancer, which include targeting the SDF-1/CXCR4 ligand/receptor pair.