Mammalian Clusterin associated protein 1 is an evolutionarily conserved protein required for ciliogenesis

BACKGROUND: Clusterin associated protein 1 (CLUAP1) was initially characterized as a protein that interacts with clusterin, and whose gene is frequently upregulated in colon cancer. Although the consequences of these observations remain unclear, research of CLUAP1 homologs in C. elegans and zebrafish indicates that it is needed for cilia assembly and maintenance in these models. To begin evaluating whether Cluap1 has an evolutionarily conserved role in cilia in mammalian systems and to explore the association of Cluap1 with disease pathogenesis and developmental abnormalities, we generated Cluap1 mutant mice. METHODS: Cluap1 mutant embryos were generated and examined for gross morphological and anatomical defects using light microscopy. Reverse transcription PCR, β-galactosidase staining assays, and immunofluorescence analysis were used to determine the expression of the gene and localization of the protein in vivo and in cultured cell lines. We also used immunofluorescence analysis and qRT-PCR to examine defects in the Sonic hedgehog signaling pathway in mutant embryos. RESULTS: Cluap1 mutant embryos die in mid-gestation, indicating that it is necessary for proper development. Mutant phenotypes include a failure of embryonic turning, an enlarged pericardial sac, and defects in neural tube development. Consistent with the diverse phenotypes, Cluap1 is widely expressed. Furthermore, the Cluap1 protein localizes to primary cilia, and mutant embryos were found to lack cilia at embryonic day 9.5. The phenotypes observed in Cluap1 mutant mice are indicative of defects in Sonic hedgehog signaling. This was confirmed by analyzing hedgehog signaling activity in Cluap1 mutants, which revealed that the pathway is repressed. CONCLUSIONS: These data indicate that the function of Cluap1 is evolutionarily conserved with regard to ciliogenesis. Further, the results implicate mammalian Cluap1 as a key regulator of hedgehog signaling and as an intraflagellar transport B complex protein. Future studies on mammalian Cluap1 utilizing this mouse model may provide insights into the role for Cluap1 in intraflagellar transport and the association with colon cancer and cystic kidney disorders

Coiled-coil domain containing 42 (Ccdc42) is necessary for proper sperm development and male fertility in the mouse

Spermiogenesis is the differentiation of spermatids into motile sperm consisting of a head and a tail. The head harbors a condensed elongated nucleus partially covered by the acrosome-acroplaxome complex. Defects in the acrosome-acroplaxome complex are associated with abnormalities in sperm head shaping. The head-tail coupling apparatus (HTCA), a complex structure consisting of two cylindrical microtubule-based centrioles and associated components, connects the tail or flagellum to the sperm head. Defects in the development of the HTCA cause sperm decapitation and disrupt sperm motility, two major contributors to male infertility. Here, we provide data indicating that mutations in the gene Coiled-coil domain containing 42 (Ccdc42) is associated with malformation of the mouse sperm flagella. In contrast to many other flagella and motile cilia genes, Ccdc42 expression is only observed in the brain and developing sperm. Male mice homozygous for a loss-of-function Ccdc42 allele (Ccdc42(KO)) display defects in the number and location of the HTCA, lack flagellated sperm, and are sterile. The testes enriched expression of Ccdc42 and lack of other phenotypes in mutant mice make it an ideal candidate for screening cases of azoospermia in humans

Making the Earth: Combining Dynamics and Chemistry in the Solar System

No terrestrial planet formation simulation completed to date has considered the detailed chemical composition of the planets produced. While many have considered possible water contents and late veneer compositions, none have examined the bulk elemental abundances of the planets produced as an important check of formation models. Here we report on the first study of this type. Bulk elemental abundances based on disk equilibrium studies have been determined for the simulated terrestrial planets of O'Brien et al. (2006). These abundances are in excellent agreement with observed planetary values, indicating that the models of O'Brien et al. (2006) are successfully producing planets comparable to those of the Solar System in terms of both their dynamical and chemical properties. Significant amounts of water are accreted in the present simulations, implying that the terrestrial planets form "wet" and do not need significant water delivery from other sources. Under the assumption of equilibrium controlled chemistry, the biogenic species N and C still need to be delivered to the Earth as they are not accreted in significant proportions during the formation process. Negligible solar photospheric pollution is produced by the planetary formation process. Assuming similar levels of pollution in other planetary systems, this in turn implies that the high metallicity trend observed in extrasolar planetary systems is in fact primordial.Comment: 61 pages (including online material), 12 figures (7 in paper, 5 online). Accepted to Icaru

Pancreatic ductal deletion of Hnf1b disrupts exocrine homeostasis, leads to pancreatitis and facilitates tumorigenesis

BACKGROUND AND AIMS: The exocrine pancreas consists of acinar cells that produce digestive enzymes transported to the intestine through a branched ductal epithelium. Chronic pancreatitis is characterized by progressive inflammation, fibrosis and loss of acinar tissue. These changes of the exocrine tissue are risk factors for pancreatic cancer. The cause of chronic pancreatitis cannot be identified in one-quarter of patients. Here, we investigated how duct dysfunction could contribute to pancreatitis development. METHODS: The transcription factor Hnf1b, first expressed in pancreatic progenitors, is strictly restricted to ductal cells from late embryogenesis. We have previously shown that Hnf1b is crucial for pancreas morphogenesis but its postnatal role still remains unelucidated. To investigate the role of pancreatic ducts in exocrine homeostasis, we inactivated Hnf1b gene in vivo in mouse ductal cells. RESULTS: We uncovered that postnatal Hnf1b inactivation in pancreatic ducts leads to chronic pancreatitis in adults. Hnf1bΔduct mutants display dilatation of ducts, loss of acinar cells, acinar-to-ductal metaplasia (ADM) and lipomatosis. We deciphered the early events involved, with downregulation of cystic disease-associated genes, loss of primary cilia, upregulation of signaling pathways, especially Yap pathway involved in ADM. Remarkably, Hnf1bΔduct mutants developed pancreatic intraepithelial neoplasia and promote PanIN progression in concert with KRAS. We further showed that adult Hnf1b inactivation in pancreatic ducts is associated with impaired regeneration after injury, with persistent metaplasia and initiation of neoplasia. CONCLUSION: Loss of Hnf1b in ductal cells leads to chronic pancreatitis and neoplasia. This reveals that Hnf1b deficiency may contribute to diseases of the exocrine pancreas and could gain further insight into the etiology of pancreatitis and tumorigenesis.Support to CH was received from theCentre National de la Recherche Scientifique (CNRS), the Universite Pierre et Marie Curie (UPMC)- Sorbonne Université , the GEFLUC - Les entreprises contre le Cancer, the Societe Francophone du Diabete (SFD)-Ypsomed, the programme Emergence UPMC. EQ was supported by a PhD fellowship from the French Ministère de la Recherche et de la Technologie. MF is an assistant engineer of the CNRS. TD and AS were supported by Sorbonne Université. MDV was supported by a PhD student fellowship from the European Marie Curie Initial Training Network (ITN)-Biology of Liver and Pancreatic Development and Disease (BOLD). O. O. was supported by a Master1 fellowship. RCP was supported by a postdoctoral fellowship from the American Heart Association (14POST20380262). MG was supported by the National Institutes of Health (U01 DK089540) and the Juvenile Diabetes Research Foundation (1-2011-592). CH is a permanent senior researcher of the Institut National de la Sante et de la Recherche Medicale (INSERM).S

Deletion of airway cilia results in noninflammatory bronchiectasis and hyperreactive airways

The mechanisms for the development of bronchiectasis and airway hyperreactivity have not been fully elucidated. Although genetic, acquired diseases and environmental influences may play a role, it is also possible that motile cilia can influence this disease process. We hypothesized that deletion of a key intraflagellar transport molecule, IFT88, in mature mice causes loss of cilia, resulting in airway remodeling. Airway cilia were deleted by knockout of IFT88, and airway remodeling and pulmonary function were evaluated. In IFT88− mice there was a substantial loss of airway cilia on respiratory epithelium. Three months after the deletion of cilia, there was clear evidence for bronchial remodeling that was not associated with inflammation or apparent defects in mucus clearance. There was evidence for airway epithelial cell hypertrophy and hyperplasia. IFT88− mice exhibited increased airway reactivity to a methacholine challenge and decreased ciliary beat frequency in the few remaining cells that possessed cilia. With deletion of respiratory cilia there was a marked increase in the number of club cells as seen by scanning electron microscopy. We suggest that airway remodeling may be exacerbated by the presence of club cells, since these cells are involved in airway repair. Club cells may be prevented from differentiating into respiratory epithelial cells because of a lack of IFT88 protein that is necessary to form a single nonmotile cilium. This monocilium is a prerequisite for these progenitor cells to transition into respiratory epithelial cells. In conclusion, motile cilia may play an important role in controlling airway structure and function

Mutation of Growth Arrest Specific 8 Reveals a Role in Motile Cilia Function and Human Disease

Ciliopathies are genetic disorders arising from dysfunction of microtubule-based cellular appendages called cilia. Different cilia types possess distinct stereotypic microtubule doublet arrangements with non-motile or ‘primary’ cilia having a 9+0 and motile cilia have a 9+2 array of microtubule doublets. Primary cilia are critical sensory and signaling centers needed for normal mammalian development. Defects in their structure/function result in a spectrum of clinical and developmental pathologies including abnormal neural tube and limb patterning. Altered patterning phenotypes in the limb and neural tube are due to perturbations in the hedgehog (Hh) signaling pathway. Motile cilia are important in fluid movement and defects in motility result in chronic respiratory infections, altered left-right asymmetry, and infertility. These features are the hallmarks of Primary Ciliary Dyskinesia (PCD, OMIM 244400). While mutations in several genes are associated with PCD in patients and animal models, the genetic lesion in many cases is unknown. We assessed the in vivo functions of Growth Arrest Specific 8 (GAS8). GAS8 shares strong sequence similarity with the Chlamydomonas Nexin-Dynein Regulatory Complex (NDRC) protein 4 (DRC4) where it is needed for proper flagella motility. In mammalian cells, the GAS8 protein localizes not only to the microtubule axoneme of motile cilia, but also to the base of non-motile cilia. Gas8 was recently implicated in the Hh signaling pathway as a regulator of Smoothened trafficking into the cilium. Here, we generate the first mouse with a Gas8 mutation and show that it causes severe PCD phenotypes; however, there were no overt Hh pathway phenotypes. In addition, we identified two human patients with missense variants in Gas8. Rescue experiments in Chlamydomonas revealed a subtle defect in swim velocity compared to controls. Further experiments using CRISPR/Cas9 homology driven repair (HDR) to generate one of these human missense variants in mice demonstrated that this allele is likely pathogenic

Connecting Planetary Composition with Formation

The rapid advances in observations of the different populations of exoplanets, the characterization of their host stars and the links to the properties of their planetary systems, the detailed studies of protoplanetary disks, and the experimental study of the interiors and composition of the massive planets in our solar system provide a firm basis for the next big question in planet formation theory. How do the elemental and chemical compositions of planets connect with their formation? The answer to this requires that the various pieces of planet formation theory be linked together in an end-to-end picture that is capable of addressing these large data sets. In this review, we discuss the critical elements of such a picture and how they affect the chemical and elemental make up of forming planets. Important issues here include the initial state of forming and evolving disks, chemical and dust processes within them, the migration of planets and the importance of planet traps, the nature of angular momentum transport processes involving turbulence and/or MHD disk winds, planet formation theory, and advanced treatments of disk astrochemistry. All of these issues affect, and are affected by the chemistry of disks which is driven by X-ray ionization of the host stars. We discuss how these processes lead to a coherent end-to-end model and how this may address the basic question.Comment: Invited review, accepted for publication in the 'Handbook of Exoplanets', eds. H.J. Deeg and J.A. Belmonte, Springer (2018). 46 pages, 10 figure

LT-IIc, a New Member of the Type II Heat-Labile Enterotoxin Family Encoded by an Escherichia coli Strain Obtained from a Nonmammalian Host ▿

Two families of bacterial heat-labile enterotoxins (HLTs) have been described: the type I HLTs are comprised of cholera toxin (CT) of Vibrio cholerae, LT-I of Escherichia coli, and several related HLTs; the type II HLTs are comprised of LT-IIa and LT-IIb. Herein, we report LT-IIc, a new type II HLT encoded from an enterotoxigenic E. coli (ETEC) strain isolated from an avian host. Using a mouse Y1 adrenal cell bioassay, LT-IIc was shown to be less cytotoxic than CT, LT-IIa, or LT-IIb. Cytotoxicity of LT-IIc was partially neutralized by antisera recognizing LT-IIa or LT-IIb but not by anti-CT antiserum. Genes encoding putative A polypeptide and B polypeptides of LT-IIc were arranged in an operon which was flanked by potential prophage sequences. Analysis of the nucleotide and predicted amino acid sequences demonstrated that the A polypeptide of LT-IIc has moderate homology to the A polypeptides of CT and LT-I and high homology to the A polypeptides of LT-IIa and LT-IIb. The B polypeptide of LT-IIc exhibited no significant homology to the B polypeptides of CT and LT-I and only moderate homology to the B polypeptides of LT-IIa and LT-IIb. The binding pattern of LT-IIc for gangliosides was distinctive from that of either LT-IIa or LT-IIb. The data suggest that other types of the type II HLT subfamily are circulating in the environment and that host specificity of type II HLT is likely governed by changes in the B polypeptide which mediate binding to receptors