Disruption of Intraflagellar Transport in Adult Mice Leads to Obesity and Slow-Onset Cystic Kidney Disease

SummaryThe assembly of primary cilia is dependant on intraflagellar transport (IFT), which mediates the bidirectional movement of proteins between the base and tip of the cilium. In mice, congenic mutations disrupting genes required for IFT (e.g., Tg737 or the IFT kinesin Kif3a) are embryonic lethal, whereas kidney-specific disruption of IFT results in severe, rapidly progressing cystic pathology [1–3]. Although the function of primary cilia in most tissues is unknown, in the kidney they are mechanosenstive organelles that detect fluid flow through the tubule lumen [4]. The loss of this flow-induced signaling pathway is thought to be a major contributing factor to cyst formation [5–7]. Recent data also suggest that there is a connection between ciliary dysfunction and obesity as evidenced by the discovery that proteins associated with human obesity syndromes such as Alström and Bardet-Biedl localize to this organelle [8]. To more directly assess the importance of cilia in postnatal life, we utilized conditional alleles of two ciliogenic genes (Tg737 and Kif3a) to systemically induce cilia loss in adults. Surprisingly, the cystic kidney pathology in these mutants is dependent on the time at which cilia loss was induced, suggesting that cyst formation is not simply caused by impaired mechanosensation. In addition to the cystic pathology, the conditional cilia mutant mice become obese, are hyperphagic, and have elevated levels of serum insulin, glucose, and leptin. We further defined where in the body cilia are required for normal energy homeostasis by disrupting cilia on neurons throughout the central nervous system and on pro-opiomelanocortin-expressing cells in the hypothalamus, both of which resulted in obesity. These data establish that neuronal cilia function in a pathway regulating satiety responses

A CreER Mouse to Study Melanin Concentrating Hormone Signaling in the Developing Brain

The neuropeptide, melanin concentrating hormone (MCH), and its G protein‐coupled receptor, melanin concentrating hormone receptor 1 (Mchr1), are expressed centrally in adult rodents. MCH signaling has been implicated in diverse behaviors such as feeding, sleep, anxiety, as well as addiction and reward. While a model utilizing the Mchr1 promoter to drive constitutive expression of Cre recombinase (Mchr1‐Cre) exists, there is a need for an inducible Mchr1‐Cre to determine the roles for this signaling pathway in neural development and adult neuronal function. Here, we generated a BAC transgenic mouse where the Mchr1 promotor drives expression of tamoxifen inducible CreER recombinase. Many aspects of the Mchr1‐Cre expression pattern are recapitulated by the Mchr1‐CreER model, though there are also notable differences. Most strikingly, compared to the constitutive model, the new Mchr1‐CreER model shows strong expression in adult animals in hypothalamic brain regions involved in feeding behavior but diminished expression in regions involved in reward, such as the nucleus accumbens. The inducible Mchr1‐CreER allele will help reveal the potential for Mchr1 signaling to impact neural development and subsequent behavioral phenotypes, as well as contribute to the understanding of the MCH signaling pathway in terminally differentiated adult neurons and the diverse behaviors that it influences

An inducible CiliaGFP mouse model for in vivo visualization and analysis of cilia in live tissue

BACKGROUND: Cilia are found on nearly every cell type in the mammalian body, and have been historically classified as either motile or immotile. Motile cilia are important for fluid and cellular movement; however, the roles of non-motile or primary cilia in most tissues remain unknown. Several genetic syndromes, called the ciliopathies, are associated with defects in cilia structure or function and have a wide range of clinical presentations. Much of what we know about the formation and maintenance of cilia comes from model systems like C. elegans and Chalmydomonas. Studies of mammalian cilia in live tissues have been hampered by difficulty visualizing them. RESULTS: To facilitate analyses of mammalian cilia function we generated an inducible Cilia(GFP) mouse by targeting mouse cDNA encoding a cilia-localized protein somatostatin receptor 3 fused to GFP (Sstr3::GFP) into the ROSA26 locus. In this system, Sstr3::GFP is expressed from the ubiquitous ROSA26 promoter after Cre mediated deletion of an upstream Neo cassette flanked by lox P sites. Fluorescent cilia labeling was observed in a variety of live tissues and after fixation. Both cell-type specific and temporally regulated cilia labeling were obtained using multiple Cre lines. The analysis of renal cilia in anesthetized live mice demonstrates that cilia commonly lay nearly parallel to the apical surface of the tubule. In contrast, in more deeply anesthetized mice the cilia display a synchronized, repetitive oscillation that ceases upon death, suggesting a relationship to heart beat, blood pressure or glomerular filtration. CONCLUSIONS: The ability to visualize cilia in live samples within the Cilia(GFP) mouse will greatly aid studies of ciliary function. This mouse will be useful for in vivo genetic and pharmacological screens to assess pathways regulating cilia motility, signaling, assembly, trafficking, resorption and length control and to study cilia regulated physiology in relation to ciliopathy phenotypes

Genetic Mosaic Analysis Indicates That the Bulb Region of Coat Hair Follicles Contains a Resident Population of Several Active Multipotent Epithelial Lineage Progenitors

AbstractThe hair follicle represents an excellent model system for exploring the properties of lineage-forming units in a dynamic epithelium containing multiple cell types. During its growth (anagen) phase, the proximal–distal axis of the mouse coat hair (pelage) follicle provides a historical record of all epithelial lineages generated from its resident stem cell population. An unresolved question in the field is whether the bulb region of anagen pelage follicles contains multipotential progenitors and whether their individual contribution to cellular census fluctuates over time. To address this issue, chimeric follicles were harvested in midanagen from three types of genetic mosaic mouse models. Analysis of the distribution of genotypic markers, including digital three-dimensional reconstruction of serially sectioned chimeric follicles, revealed that on average the bulb contains four or fewer active progenitors, each capable of giving rise to all six follicular epithelial fates. Moreover, analysis of mosaic pelage, as well as cultured whisker follicles provided evidence that bulb-associated progenitors can give rise to expanding descendant clones during midanagen, leading to the conclusion that the bulb contains dormant or symmetrically dividing stem cells. This latter feature resembles the behavior of hematopoietic stem cells after bone marrow transplantation, and raises the question of whether this property may be shared by stem cells in other self-renewing epithelia

Disease Extent at Secondary Cytoreductive Surgery is Predictive of Progression-free and Overall Survival in Advanced Stage Ovarian Cancer: an NRG Oncology/Gynecologic Oncology Group study

Purpose GOG 152 was a randomized trial of secondary cytoreductive surgery (SCS) in patients with suboptimal residual disease (residual tumor nodule >1 cm in greatest diameter) following primary cytoreductive surgery for advanced stage ovarian cancer. The current analysis was undertaken to evaluate the impact of disease findings at SCS on progression-free survival (PFS) and overall survival (OS). Methods Among the 550 patients enrolled on GOG-152, two-hundred-sixteen patients were randomly assigned following 3 cycles of cisplatin and paclitaxel to receive SCS. In 15 patients (7%) surgery was declined or contraindicated. In the remaining 201 patients the operative and pathology reports were utilized to classify their disease status at the beginning of SCS as; no gross disease/microscopically negative N= 40 (19.9%), no gross disease/microscopically positive N= 8 (4.0%), and gross disease N=153 (76.1%). Results The median PFS for patients with no gross disease/microscopically negative was 16.1 months, no gross disease/microscopically positive was 13.5 months and for gross disease was 11.7 months, p=0.002. The median OS for patients with no gross disease/microscopically negative was 51.5 months, no gross disease/microscopically positive was 42.6 months and for gross disease was 34.9 months, p=0.018. Conclusion Although as previously reported SCS did not change PFS or OS, for those who underwent the procedure, their operative and pathologic findings were predictive of PFS and OS. Surgical/pathological residual disease is a biomarker of response to chemotherapy and predictive of PFS and OS

Genome-wide association study evaluating single-nucleotide polymorphisms and outcomes in patients with advanced stage serous ovarian or primary peritoneal cancer: An NRG Oncology/Gynecologic Oncology Group study

This study evaluated single nucleotide polymorphisms (SNPs) associated with progression free (PFS) and overall survival (OS) in patients with advanced stage serous EOC

Mitochondrial Genetic Background Modulates Bioenergetics and Susceptibility to Acute Cardiac Volume Overload

Dysfunctional bioenergetics has emerged as a key feature in many chronic pathologies such as diabetes and cardiovascular disease. This has led to the mitochondrial paradigm in which it has been proposed that mtDNA sequence variation contributes to disease susceptibility. In the present study we show a novel animal model of mtDNA polymorphisms, the MNX (mitochondrial–nuclear exchange) mouse, in which the mtDNA from the C3H/HeN mouse has been inserted on to the C57/BL6 nuclear background and vice versa to test this concept. Our data show a major contribution of the C57/BL6 mtDNA to the susceptibility to the pathological stress of cardiac volume overload which is independent of the nuclear background. Mitochondria harbouring the C57/BL6J mtDNA generate more ROS (reactive oxygen species) and have a higher mitochondrial membrane potential relative to those with C3H/HeN mtDNA, independent of nuclear background. We propose this is the primary mechanism associated with increased bioenergetic dysfunction in response to volume overload. In summary, these studies support the ‘mitochondrial paradigm’ for the development of disease susceptibility, and show that the mtDNA modulates cellular bioenergetics, mitochondrial ROS generation and susceptibility to cardiac stress