1
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Refai O, Rodriguez P, Gichi Z, Blakely RD. Forward genetic screen of the C. elegans million mutation library reveals essential, cell-autonomous contributions of BBSome proteins to dopamine signaling. J Neurochem 2024. [PMID: 39118406 DOI: 10.1111/jnc.16188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2024] [Revised: 07/11/2024] [Accepted: 07/12/2024] [Indexed: 08/10/2024]
Abstract
The nematode Caenorhabditis elegans is well known for its ability to support forward genetic screens to identify molecules involved in neuronal viability and signaling. The proteins involved in C. elegans dopamine (DA) regulation are highly conserved across evolution, with prior work demonstrating that the model can serve as an efficient platform to identify novel genes involved in disease-associated processes. To identify novel players in DA signaling, we took advantage of a recently developed library of pre-sequenced mutant nematodes arising from the million mutation project (MMP) to identify strains that display the DA-dependent swimming-induced-paralysis phenotype (Swip). Our screen identified novel mutations in the dopamine transporter encoding gene dat-1, whose loss was previously used to identify the Swip phenotype, as well as multiple genes with previously unknown connections to DA signaling. Here, we present our isolation and characterization of one of these genes, bbs-1, previously linked to the function of primary cilia in worms and higher organisms, including humans, and where loss-of-function mutations result in a human disorder known as Bardet-Biedl syndrome. Our studies of C. elegans BBS-1 protein, as well as other proteins that are known to be assembled into a higher order complex (the BBSome) reveal that functional or structural disruption of this complex leads to exaggerated C. elegans DA signaling to produce Swip via a cell-autonomous mechanism. We provide evidence that not only does the proper function of cilia in C. elegans DA neurons support normal swimming behavior, but also that bbs-1 maintains normal levels of DAT-1 trafficking or function via a RHO-1 and SWIP-13/MAPK-15 dependent pathway where mutants may contribute to Swip independent of altered ciliary function. Together, these studies demonstrate novel contributors to DA neuron function in the worm and demonstrate the utility and efficiency of forward genetic screens using the MMP library.
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Affiliation(s)
- Osama Refai
- Department of Biomedical Science, Florida Atlantic University, Boca Raton, Florida, USA
| | - Peter Rodriguez
- Department of Biomedical Science, Florida Atlantic University, Boca Raton, Florida, USA
| | - Zayna Gichi
- Department of Biomedical Science, Florida Atlantic University, Boca Raton, Florida, USA
| | - Randy D Blakely
- Department of Biomedical Science, Florida Atlantic University, Boca Raton, Florida, USA
- Stiles-Nicholson Brain Institute, Florida Atlantic University, Jupiter, Florida, USA
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2
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Rodrigues DT, Padilha HA, Soares ATG, de Souza MEO, Guerra MT, Ávila DS. The Caenorhabditis elegans neuroendocrine system and their modulators: An overview. Mol Cell Endocrinol 2024; 586:112191. [PMID: 38382589 DOI: 10.1016/j.mce.2024.112191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 02/16/2024] [Accepted: 02/19/2024] [Indexed: 02/23/2024]
Abstract
In this review we seek to systematically bring what has been published in the literature about the nervous system, endocrine system, neuroendocrine relationships, neuroendocrine modulations and endocrine disruptors in the alternative model Caenorhabditis elegans. The serotonergic, dopaminergic, GABAergic and glutamatergic neurotransmitters are related to the modulation of the neuroendocrine axis, leading to the activation or inhibition of several processes that occur in the worm through distinct and interconnected pathways. Furthermore, this review addresses the gut-neuronal axis as it has been revealed in recent years that gut microbiota impacts on neuronal functions. This review also approaches xenobiotics that can positively or negatively impact the neuroendocrine system in C. elegans as in mammals, which allows the application of this nematode to screen new drugs and to identify toxicants that are endocrine disruptors.
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Affiliation(s)
- Daniela Teixeira Rodrigues
- Graduation Program in Biological Sciences- Toxicological Biochemistry, Federal University of Santa Maria, RS, Brazil
| | | | | | | | | | - Daiana Silva Ávila
- Graduation Program in Biological Sciences- Toxicological Biochemistry, Federal University of Santa Maria, RS, Brazil; Graduation Program in Biochemistry, Federal University of Pampa, Uruguaiana, RS, Brazil.
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3
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Tomlinson JW. Bardet-Biedl syndrome: A focus on genetics, mechanisms and metabolic dysfunction. Diabetes Obes Metab 2024; 26 Suppl 2:13-24. [PMID: 38302651 DOI: 10.1111/dom.15480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 01/18/2024] [Accepted: 01/18/2024] [Indexed: 02/03/2024]
Abstract
Bardet-Biedl syndrome (BBS) is a rare, monogenic, multisystem disorder characterized by retinal dystrophy, renal abnormalities, polydactyly, learning disabilities, as well as metabolic dysfunction, including obesity and an increased risk of type 2 diabetes. It is a primary ciliopathy, and causative mutations in more than 25 different genes have been described. Multiple cellular mechanisms contribute to the development of the metabolic phenotype associated with BBS, including hyperphagia as a consequence of altered hypothalamic appetite signalling as well as alterations in adipocyte biology promoting adipocyte proliferation and adipogenesis. Within this review, we describe in detail the metabolic phenotype associated with BBS and discuss the mechanisms that drive its evolution. In addition, we review current approaches to the metabolic management of patients with BBS, including the use of weight loss medications and bariatric surgery. Finally, we evaluate the potential of targeting hypothalamic appetite signalling to limit hyperphagia and induce clinically significant weight loss.
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Affiliation(s)
- Jeremy W Tomlinson
- Oxford Centre for Diabetes, Endocrinology and Metabolism, NIHR Oxford Biomedical Research Centre, University of Oxford, Churchill Hospital, Oxford, UK
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4
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Huang M, Wang Y, Chow CH, Stepien KP, Indrawinata K, Xu J, Argiropoulos P, Xie X, Sugita K, Tien CW, Lee S, Monnier PP, Rizo J, Gao S, Sugita S. Double mutation of open syntaxin and UNC-18 P334A leads to excitatory-inhibitory imbalance and impairs multiple aspects of C. elegans behavior. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.18.553709. [PMID: 37645974 PMCID: PMC10462135 DOI: 10.1101/2023.08.18.553709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
Abstract
SNARE and Sec/Munc18 proteins are essential in synaptic vesicle exocytosis. Open form t-SNARE syntaxin and UNC-18 P334A are well-studied exocytosis-enhancing mutants. Here we investigate the interrelationship between the two mutations by generating double mutants in various genetic backgrounds in C. elegans. While each single mutation rescued the motility of CAPS/unc-31 and synaptotagmin/snt-1 mutants significantly, double mutations unexpectedly worsened motility or lost their rescuing effects. Electrophysiological analyses revealed that simultaneous mutations of open syntaxin and gain-of-function P334A UNC-18 induces a strong imbalance of excitatory over inhibitory transmission. In liposome fusion assays performed with mammalian proteins, the enhancement of fusion caused by the two mutations individually was abolished when the two mutations were introduced simultaneously, consistent with what we observed in C. elegans. We conclude that open syntaxin and P334A UNC-18 do not have additive beneficial effects, and this extends to C. elegans' characteristics such as motility, growth, offspring bared, body size, and exocytosis, as well as liposome fusion in vitro. Our results also reveal unexpected differences between the regulation of exocytosis in excitatory versus inhibitory synapses.
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Affiliation(s)
- Mengjia Huang
- Division of Experimental & Translational Neuroscience, Krembil Brain Institute, University Health Network, Ontario, M5T 0S8, Canada
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, M5S 1A8, Canada
| | - Ya Wang
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Chun Hin Chow
- Division of Experimental & Translational Neuroscience, Krembil Brain Institute, University Health Network, Ontario, M5T 0S8, Canada
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, M5S 1A8, Canada
| | - Karolina P. Stepien
- Departments of Biophysics, Biochemistry and Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas, 75390, USA
| | - Karen Indrawinata
- Division of Experimental & Translational Neuroscience, Krembil Brain Institute, University Health Network, Ontario, M5T 0S8, Canada
| | - Junjie Xu
- Departments of Biophysics, Biochemistry and Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas, 75390, USA
| | - Peter Argiropoulos
- Division of Experimental & Translational Neuroscience, Krembil Brain Institute, University Health Network, Ontario, M5T 0S8, Canada
| | - Xiaoyu Xie
- Division of Experimental & Translational Neuroscience, Krembil Brain Institute, University Health Network, Ontario, M5T 0S8, Canada
- Department of Anesthesiology, Dalian Municipal Friendship Hospital, Dalian Medical University, Dalian, Liaoning, China
| | - Kyoko Sugita
- Donald K. Johnson Eye Institute, University Health Network, Ontario, M5T 0S8, Canada; Department of Ophthalmology & Vision Sciences, University of Toronto, Toronto, Ontario, M5S 1A8, Canada
| | - Chi-Wei Tien
- Division of Experimental & Translational Neuroscience, Krembil Brain Institute, University Health Network, Ontario, M5T 0S8, Canada
| | - Soomin Lee
- Division of Experimental & Translational Neuroscience, Krembil Brain Institute, University Health Network, Ontario, M5T 0S8, Canada
| | - Philippe P. Monnier
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, M5S 1A8, Canada
- Donald K. Johnson Eye Institute, University Health Network, Ontario, M5T 0S8, Canada; Department of Ophthalmology & Vision Sciences, University of Toronto, Toronto, Ontario, M5S 1A8, Canada
| | - Josep Rizo
- Department of Anesthesiology, Dalian Municipal Friendship Hospital, Dalian Medical University, Dalian, Liaoning, China
| | - Shangbang Gao
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, 430074, China
- Key Laboratory of Vascular Aging of the Ministry of Education, Tongji Hospital of Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Shuzo Sugita
- Division of Experimental & Translational Neuroscience, Krembil Brain Institute, University Health Network, Ontario, M5T 0S8, Canada
- Department of Physiology, Temerty Faculty of Medicine, University of Toronto, Toronto, Ontario, M5S 1A8, Canada
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5
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ROS and cGMP signaling modulate persistent escape from hypoxia in Caenorhabditis elegans. PLoS Biol 2022; 20:e3001684. [PMID: 35727855 PMCID: PMC9249223 DOI: 10.1371/journal.pbio.3001684] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 07/01/2022] [Accepted: 05/20/2022] [Indexed: 12/02/2022] Open
Abstract
The ability to detect and respond to acute oxygen (O2) shortages is indispensable to aerobic life. The molecular mechanisms and circuits underlying this capacity are poorly understood. Here, we characterize the behavioral responses of feeding Caenorhabditis elegans to approximately 1% O2. Acute hypoxia triggers a bout of turning maneuvers followed by a persistent switch to rapid forward movement as animals seek to avoid and escape hypoxia. While the behavioral responses to 1% O2 closely resemble those evoked by 21% O2, they have distinct molecular and circuit underpinnings. Disrupting phosphodiesterases (PDEs), specific G proteins, or BBSome function inhibits escape from 1% O2 due to increased cGMP signaling. A primary source of cGMP is GCY-28, the ortholog of the atrial natriuretic peptide (ANP) receptor. cGMP activates the protein kinase G EGL-4 and enhances neuroendocrine secretion to inhibit acute responses to 1% O2. Triggering a rise in cGMP optogenetically in multiple neurons, including AIA interneurons, rapidly and reversibly inhibits escape from 1% O2. Ca2+ imaging reveals that a 7% to 1% O2 stimulus evokes a Ca2+ decrease in several neurons. Defects in mitochondrial complex I (MCI) and mitochondrial complex I (MCIII), which lead to persistently high reactive oxygen species (ROS), abrogate acute hypoxia responses. In particular, repressing the expression of isp-1, which encodes the iron sulfur protein of MCIII, inhibits escape from 1% O2 without affecting responses to 21% O2. Both genetic and pharmacological up-regulation of mitochondrial ROS increase cGMP levels, which contribute to the reduced hypoxia responses. Our results implicate ROS and precise regulation of intracellular cGMP in the modulation of acute responses to hypoxia by C. elegans. The ability to detect and respond to acute oxygen shortages is indispensable to aerobic life, but the molecular mechanisms underlying this capacity are poorly understood. This study reveals that high levels of cGMP and reactive oxygen species (ROS) prevent the nematode Caenorhabditis elegans from escaping hypoxia.
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6
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Zhang X, Liu J, Pan T, Ward A, Liu J, Xu XZS. A cilia-independent function of BBSome mediated by DLK-MAPK signaling in C. elegans photosensation. Dev Cell 2022; 57:1545-1557.e4. [PMID: 35649417 DOI: 10.1016/j.devcel.2022.05.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 04/03/2022] [Accepted: 05/04/2022] [Indexed: 11/03/2022]
Abstract
Bardet-Biedl syndrome (BBS) is a genetic disorder that affects primary cilia. BBSome, a protein complex composed of eight BBS proteins, regulates the structure and function of cilia, and its malfunction causes BBS in humans. Here, we report a cilia-independent function of BBSome. To identify genes that regulate the C. elegans photoreceptor protein LITE-1 in ciliated ASH photosensory neurons, we performed a genetic screen and isolated bbs mutants. Functional analysis revealed that BBSome regulates LITE-1 protein stability independently of cilia. Through another round of genetic screening, we found that this cilia-independent function of BBSome is mediated by DLK-MAPK signaling, which acts downstream of BBSome to control LITE-1 stability via Rab5-mediated endocytosis. BBSome exerts its function by regulating the expression of DLK. BBSome also regulates the expression of LZK, a mammalian DLK in human cells. These studies identify a cilia-independent function of BBSome and uncover DLK as an evolutionarily conserved BBSome effector.
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Affiliation(s)
- Xinxing Zhang
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA; Department of Molecular and Integrative Physiology, University of Michigan Medical, School, Ann Arbor, MI 48109, USA
| | - Jinzhi Liu
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA; Department of Molecular and Integrative Physiology, University of Michigan Medical, School, Ann Arbor, MI 48109, USA; College of Life Science and Technology, Key Laboratory of Molecular Biophysics of MOE, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - Tong Pan
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA; Department of Molecular and Integrative Physiology, University of Michigan Medical, School, Ann Arbor, MI 48109, USA
| | - Alex Ward
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Jianfeng Liu
- College of Life Science and Technology, Key Laboratory of Molecular Biophysics of MOE, Huazhong University of Science and Technology, Wuhan, Hubei 430074, China
| | - X Z Shawn Xu
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, USA; Department of Molecular and Integrative Physiology, University of Michigan Medical, School, Ann Arbor, MI 48109, USA.
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7
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Adams S, Pathak P, Kittelman M, Jones ARC, Mallon EB, Pires-daSilva A. Sexual morph specialisation in a trioecious nematode balances opposing selective forces. Sci Rep 2022; 12:6402. [PMID: 35431314 PMCID: PMC9013718 DOI: 10.1038/s41598-022-09900-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 03/10/2022] [Indexed: 11/27/2022] Open
Abstract
The coexistence of different mating strategies, whereby a species can reproduce both by selfing and outcrossing, is an evolutionary enigma. Theory predicts two predominant stable mating states: outcrossing with strong inbreeding depression or selfing with weak inbreeding depression. As these two mating strategies are subject to opposing selective forces, mixed breeding systems are thought to be a rare transitory state yet can persist even after multiple speciation events. We hypothesise that if each mating strategy plays a distinctive role during some part of the species life history, opposing selective pressures could be balanced, permitting the stable co-existence of selfing and outcrossing sexual morphs. In this scenario, we would expect each morph to be specialised in their respective roles. Here we show, using behavioural, physiological and gene expression studies, that the selfing (hermaphrodite) and outcrossing (female) sexual morphs of the trioecious nematode Auanema freiburgensis have distinct adaptations optimised for their different roles during the life cycle. A. freiburgensis hermaphrodites are known to be produced under stressful conditions and are specialised for dispersal to new habitat patches. Here we show that they exhibit metabolic and intestinal changes enabling them to meet the cost of dispersal and reproduction. In contrast, A. freiburgensis females are produced in favourable conditions and facilitate rapid population growth. We found that females compensate for the lack of reproductive assurance by reallocating resources from intestinal development to mate-finding behaviour. The specialisation of each mating system for its role in the life cycle could balance opposing selective forces allowing the stable maintenance of both mating systems in A. freiburgensis.
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8
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Valperga G, de Bono M. Impairing one sensory modality enhances another by reconfiguring peptidergic signalling in Caenorhabditis elegans. eLife 2022; 11:68040. [PMID: 35201977 PMCID: PMC8871372 DOI: 10.7554/elife.68040] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 02/07/2022] [Indexed: 12/05/2022] Open
Abstract
Animals that lose one sensory modality often show augmented responses to other sensory inputs. The mechanisms underpinning this cross-modal plasticity are poorly understood. We probe such mechanisms by performing a forward genetic screen for mutants with enhanced O2 perception in Caenorhabditis elegans. Multiple mutants exhibiting increased O2 responsiveness concomitantly show defects in other sensory responses. One mutant, qui-1, defective in a conserved NACHT/WD40 protein, abolishes pheromone-evoked Ca2+ responses in the ADL pheromone-sensing neurons. At the same time, ADL responsiveness to pre-synaptic input from O2-sensing neurons is heightened in qui-1, and other sensory defective mutants, resulting in enhanced neurosecretion although not increased Ca2+ responses. Expressing qui-1 selectively in ADL rescues both the qui-1 ADL neurosecretory phenotype and enhanced escape from 21% O2. Profiling ADL neurons in qui-1 mutants highlights extensive changes in gene expression, notably of many neuropeptide receptors. We show that elevated ADL expression of the conserved neuropeptide receptor NPR-22 is necessary for enhanced ADL neurosecretion in qui-1 mutants, and is sufficient to confer increased ADL neurosecretion in control animals. Sensory loss can thus confer cross-modal plasticity by changing the peptidergic connectome.
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Affiliation(s)
- Giulio Valperga
- Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom.,Institute of Science and Technology Austria (IST Austria), Klosterneuburg, Austria
| | - Mario de Bono
- Cell Biology Division, MRC Laboratory of Molecular Biology, Cambridge, United Kingdom.,Institute of Science and Technology Austria (IST Austria), Klosterneuburg, Austria
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9
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Pablos M, Casanueva-Álvarez E, González-Casimiro CM, Merino B, Perdomo G, Cózar-Castellano I. Primary Cilia in Pancreatic β- and α-Cells: Time to Revisit the Role of Insulin-Degrading Enzyme. Front Endocrinol (Lausanne) 2022; 13:922825. [PMID: 35832432 PMCID: PMC9271624 DOI: 10.3389/fendo.2022.922825] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Accepted: 05/24/2022] [Indexed: 12/25/2022] Open
Abstract
The primary cilium is a narrow organelle located at the surface of the cell in contact with the extracellular environment. Once underappreciated, now is thought to efficiently sense external environmental cues and mediate cell-to-cell communication, because many receptors, ion channels, and signaling molecules are highly or differentially expressed in primary cilium. Rare genetic disorders that affect cilia integrity and function, such as Bardet-Biedl syndrome and Alström syndrome, have awoken interest in studying the biology of cilium. In this review, we discuss recent evidence suggesting emerging roles of primary cilium and cilia-mediated signaling pathways in the regulation of pancreatic β- and α-cell functions, and its implications in regulating glucose homeostasis.
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Affiliation(s)
- Marta Pablos
- Department of Biochemistry, Molecular Biology and Physiology, School of Medicine, University of Valladolid, Valladolid, Spain
- *Correspondence: Marta Pablos,
| | - Elena Casanueva-Álvarez
- Unidad de Excelencia Instituto de Biología y Genética Molecular, University of Valladolid Consejo Superior de Investigaciones Científicas (CSIC), Valladolid, Spain
| | - Carlos M. González-Casimiro
- Unidad de Excelencia Instituto de Biología y Genética Molecular, University of Valladolid Consejo Superior de Investigaciones Científicas (CSIC), Valladolid, Spain
| | - Beatriz Merino
- Unidad de Excelencia Instituto de Biología y Genética Molecular, University of Valladolid Consejo Superior de Investigaciones Científicas (CSIC), Valladolid, Spain
| | - Germán Perdomo
- Unidad de Excelencia Instituto de Biología y Genética Molecular, University of Valladolid Consejo Superior de Investigaciones Científicas (CSIC), Valladolid, Spain
| | - Irene Cózar-Castellano
- Department of Biochemistry, Molecular Biology and Physiology, School of Medicine, University of Valladolid, Valladolid, Spain
- Unidad de Excelencia Instituto de Biología y Genética Molecular, University of Valladolid Consejo Superior de Investigaciones Científicas (CSIC), Valladolid, Spain
- Instituto de Salud Carlos III, Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Madrid, Spain
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10
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Wang M, Witvliet D, Wu M, Kang L, Shao Z. Temperature regulates synaptic subcellular specificity mediated by inhibitory glutamate signaling. PLoS Genet 2021; 17:e1009295. [PMID: 33428618 PMCID: PMC7822552 DOI: 10.1371/journal.pgen.1009295] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 01/22/2021] [Accepted: 12/05/2020] [Indexed: 01/13/2023] Open
Abstract
Environmental factors such as temperature affect neuronal activity and development. However, it remains unknown whether and how they affect synaptic subcellular specificity. Here, using the nematode Caenorhabditis elegans AIY interneurons as a model, we found that high cultivation temperature robustly induces defects in synaptic subcellular specificity through glutamatergic neurotransmission. Furthermore, we determined that the functional glutamate is mainly released by the ASH sensory neurons and sensed by two conserved inhibitory glutamate-gated chloride channels GLC-3 and GLC-4 in AIY. Our work not only presents a novel neurotransmission-dependent mechanism underlying the synaptic subcellular specificity, but also provides a potential mechanistic insight into high-temperature-induced neurological defects.
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Affiliation(s)
- Mengqing Wang
- Department of Neurosurgery, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Daniel Witvliet
- Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Mengting Wu
- Department of Neurosurgery, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Lijun Kang
- Department of Neurobiology and Department of Neurosurgery of the First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang, China
| | - Zhiyong Shao
- Department of Neurosurgery, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Zhongshan Hospital, Fudan University, Shanghai, China
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11
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Podraza-Farhanieh A, Natarajan B, Raj D, Kao G, Naredi P. ENPL-1, the Caenorhabditis elegans homolog of GRP94, promotes insulin secretion via regulation of proinsulin processing and maturation. Development 2020; 147:dev190082. [PMID: 33037039 PMCID: PMC10666919 DOI: 10.1242/dev.190082] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Accepted: 09/28/2020] [Indexed: 12/27/2022]
Abstract
Insulin/IGF signaling in Caenorhabditis elegans is crucial for proper development of the dauer larva and growth control. Mutants disturbing insulin processing, secretion and downstream signaling perturb this process and have helped identify genes that affect progression of type 2 diabetes. Insulin maturation is required for its proper secretion by pancreatic β cells. The role of the endoplasmic reticulum (ER) chaperones in insulin processing and secretion needs further study. We show that the C. elegans ER chaperone ENPL-1/GRP94 (HSP90B1), acts in dauer development by promoting insulin secretion and signaling. Processing of a proinsulin likely involves binding between the two proteins via a specific domain. We show that, in enpl-1 mutants, an unprocessed insulin exits the ER lumen and is found in dense core vesicles, but is not secreted. The high ER stress in enpl-1 mutants does not cause the secretion defect. Importantly, increased ENPL-1 levels result in increased secretion. Taken together, our work indicates that ENPL-1 operates at the level of insulin availability and is an essential modulator of insulin processing and secretion.
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Affiliation(s)
- Agnieszka Podraza-Farhanieh
- Department of Surgery, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, SE413 45 Gothenburg, Sweden
| | | | - Dorota Raj
- Department of Surgery, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, SE413 45 Gothenburg, Sweden
| | - Gautam Kao
- Department of Surgery, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, SE413 45 Gothenburg, Sweden
| | - Peter Naredi
- Department of Surgery, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, SE413 45 Gothenburg, Sweden
- Department of Surgery, Sahlgrenska University Hospital, SE413 45 Gothenburg, Sweden
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12
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Cruz-Corchado J, Ooi FK, Das S, Prahlad V. Global Transcriptome Changes That Accompany Alterations in Serotonin Levels in Caenorhabditis elegans. G3 (BETHESDA, MD.) 2020; 10:1225-1246. [PMID: 31996358 PMCID: PMC7144078 DOI: 10.1534/g3.120.401088] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 01/25/2020] [Indexed: 11/18/2022]
Abstract
Serotonin (5-hydroxytryptamine, 5-HT), is a phylogenetically ancient molecule best characterized as a neurotransmitter that modulates multiple aspects of mood and social cognition. The roles that 5-HT plays in normal and abnormal behavior are not fully understood but have been posited to be due to its common function as a 'defense signal'. However, 5-HT levels also systemically impact cell physiology, modulating cell division, migration, apoptosis, mitochondrial biogenesis, cellular metabolism and differentiation. Whether these diverse cellular effects of 5-HT also share a common basis is unclear. C. elegans provides an ideal system to interrogate the systemic effects of 5-HT, since lacking a blood-brain barrier, 5-HT synthesized and released by neurons permeates the organism to modulate neuronal as well as non-neuronal cells throughout the body. Here we used RNA-Seq to characterize the systemic changes in gene expression that occur in C. elegans upon altering 5-HT levels, and compared the transcriptomes to published datasets. We find that an acute increase in 5-HT is accompanied by a global decrease in gene expression levels, upregulation of genes involved in stress pathways, changes that significantly correlate with the published transcriptomes of animals that have activated defense and immune responses, and an increase in levels of phosphorylated eukaryotic initiation factor, eIF2α. In 5-HT deficient animals lacking tryptophan hydroxylase (tph-1(mg280)II) there is a net increase in gene expression, with an overrepresentation of genes related to development and chromatin. Surprisingly, the transcriptomes of animals with acute increases in 5-HT levels, and 5-HT deficiency do not overlap with transcriptomes of mutants with whom they share striking physiological resemblance. These studies are the first to catalog systemic transcriptome changes that occur upon alterations in 5-HT levels. They further show that in C. elegans changes in gene expression upon altering 5-HT levels, and changes in physiology, are not directly correlated.
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Affiliation(s)
- Johnny Cruz-Corchado
- Department of Biology, Aging Mind and Brain Initiative, Iowa Neuroscience Institute, 143 Biology Building, Iowa City, IA 52242-1324
| | - Felicia K Ooi
- Department of Biology, Aging Mind and Brain Initiative, Iowa Neuroscience Institute, 143 Biology Building, Iowa City, IA 52242-1324
| | - Srijit Das
- Department of Biology, Aging Mind and Brain Initiative, Iowa Neuroscience Institute, 143 Biology Building, Iowa City, IA 52242-1324
| | - Veena Prahlad
- Department of Biology, Aging Mind and Brain Initiative, Iowa Neuroscience Institute, 143 Biology Building, Iowa City, IA 52242-1324
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Horiuchi K, Kogiso T, Sagawa T, Ito T, Taniai M, Miura K, Hattori M, Morisada N, Hashimoto E, Tokushige K. Bardet-Biedl Syndrome Caused by Skipping of SCLT1 Complicated by Microvesicular Steatohepatitis. Intern Med 2020; 59:2719-2724. [PMID: 33132306 PMCID: PMC7691027 DOI: 10.2169/internalmedicine.5045-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
We treated the case of a 22-year-old male patient with liver dysfunction. At 1 year of age, hepatic fibrosis was suspected. In addition, due to the presence of retinitis pigmentosa, renal failure, obesity, mental retardation, and hypogonadism, he was diagnosed with Bardet-Biedl syndrome (BBS). Skipping of exons 14 and 17 in the sodium channel and clathrin linker 1 (SCLT1) gene was observed. At 22 years of age, the liver enzyme levels were further elevated and a diagnosis of microvesicular steatohepatitis was made. Insulin resistance, a reduction of muscle mass, an impairment of the fatty acid metabolism, and hyperleptinemia in this syndrome may cause steatohepatitis.
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Affiliation(s)
- Kentaro Horiuchi
- Institute of Gastroenterology, Department of Internal Medicine, Tokyo Women's Medical University, Japan
| | - Tomomi Kogiso
- Institute of Gastroenterology, Department of Internal Medicine, Tokyo Women's Medical University, Japan
| | - Takaomi Sagawa
- Institute of Gastroenterology, Department of Internal Medicine, Tokyo Women's Medical University, Japan
| | - Taito Ito
- Institute of Gastroenterology, Department of Internal Medicine, Tokyo Women's Medical University, Japan
| | - Makiko Taniai
- Institute of Gastroenterology, Department of Internal Medicine, Tokyo Women's Medical University, Japan
| | - Kenichiro Miura
- Department of Pediatric Nephrology, Tokyo Women's Medical University, Japan
| | - Motoshi Hattori
- Department of Pediatric Nephrology, Tokyo Women's Medical University, Japan
| | - Naoya Morisada
- Department of Pediatrics, Kobe University Graduate School of Medicine, Japan
| | | | - Katsutoshi Tokushige
- Institute of Gastroenterology, Department of Internal Medicine, Tokyo Women's Medical University, Japan
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Lodh S. Primary Cilium, An Unsung Hero in Maintaining Functional β-cell Population. THE YALE JOURNAL OF BIOLOGY AND MEDICINE 2019; 92:471-480. [PMID: 31543709 PMCID: PMC6747938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Abstract
A primary challenge in type 2 diabetes (T2D) is the preservation of a functional population of β-cells, which play a central role in regulating blood glucose levels. Two congenital disorders, Bardet-Biedl syndrome (BBS) and Alström syndrome (ALMS), can serve as useful models to understand how β-cells are normally produced and regenerated. Both are characterized by obesity, loss of β-cells, and defects in primary cilia - the sensory center of cells. Primary cilia are cellular protrusions present in almost every vertebrate cell. This antenna-like organelle plays a crucial role in regulating several signaling pathways that direct proper development, proliferation, and homeostasis. Mutations in genes expressing ciliary proteins or proteins present at or near the base of the cilium lead to disorders, collectively called ciliopathies. BBS and Alström syndrome are such disorders. Though both BBS and Alström patients are obese, their childhood diabetes rates are vastly different, suggesting distinct pathogenesis underlying these two ciliopathies. Clinical studies suggest that BBS patients are protected against early onset diabetes by sustained or enhanced β-cell function. In contrast, Alström patients are more prone to develop diabetes. They have hyperinsulinemia, yet their β-cells fail to sense glucose and to regulate insulin secretion accordingly. These data suggest a potential role for primary cilia in maintaining a functional β-cell population and that defects in cilia or in ciliary proteins impair development and function of β-cells. Identifying the respective roles of primary cilia and ciliary proteins, such as BBS and ALMS1 may shed light on β-cell biology and uncover potentially novel targets for diabetes therapy.
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Affiliation(s)
- Sukanya Lodh
- To whom all correspondence should be addressed: Sukanya Lodh, Department of Biological sciences, Marquette University, 1428 W. Clybourn St., Milwaukee, WI 53233; Tel: 802-881-6221, Email address:
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Trafficking of ciliary membrane proteins by the intraflagellar transport/BBSome machinery. Essays Biochem 2018; 62:753-763. [PMID: 30287585 DOI: 10.1042/ebc20180030] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 09/04/2018] [Accepted: 09/19/2018] [Indexed: 12/13/2022]
Abstract
Bardet-Biedl syndrome (BBS) is a rare inherited disease caused by defects in the BBSome, an octameric complex of BBS proteins. The BBSome is conserved in most organisms with cilia, which are microtubule (MT)-based cell organelles that protrude from the cell surface and function in motility and sensing. Cilia assembly, maintenance, and function require intraflagellar transport (IFT), a bidirectional motility of multi-megadalton IFT trains propelled by molecular motors along the ciliary MTs. IFT has been shown to transport structural proteins, including tubulin, into growing cilia. The BBSome is an adapter for the transport of ciliary membrane proteins and cycles through cilia via IFT. While both the loss and the abnormal accumulation of ciliary membrane proteins have been observed in bbs mutants, recent data converge on a model where the BBSome mainly functions as a cargo adapter for the removal of certain transmembrane and peripheral membrane proteins from cilia. Here, we review recent data on the ultrastructure of the BBSome and how the BBSome recognizes its cargoes and mediates their removal from cilia.
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Vohra M, Lemieux GA, Lin L, Ashrafi K. Kynurenic acid accumulation underlies learning and memory impairment associated with aging. Genes Dev 2018; 32:14-19. [PMID: 29386332 PMCID: PMC5828390 DOI: 10.1101/gad.307918.117] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 12/22/2017] [Indexed: 12/27/2022]
Abstract
Vohra et al. show that in C. elegans, a significant portion of the decline in learning and memory associated with aging is due to accumulation of a metabolite called kynurenic acid (KYNA), an endogenous antagonist of neural NMDA receptors. A general feature of animal aging is decline in learning and memory. Here we show that in Caenorhabditis elegans, a significant portion of this decline is due to accumulation of kynurenic acid (KYNA), an endogenous antagonist of neural N-methyl-D-aspartate receptors (NMDARs). We show that activation of a specific pair of interneurons either through genetic means or by depletion of KYNA significantly improves learning capacity in aged animals even when the intervention is applied in aging animals. KYNA depletion also improves memory. We show that insulin signaling is one factor in KYNA accumulation.
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Affiliation(s)
- Mihir Vohra
- Department of Physiology, University of California at San Francisco, San Francisco California 94158, USA
| | - George A Lemieux
- Department of Physiology, University of California at San Francisco, San Francisco California 94158, USA
| | - Lin Lin
- Department of Physiology, University of California at San Francisco, San Francisco California 94158, USA
| | - Kaveh Ashrafi
- Department of Physiology, University of California at San Francisco, San Francisco California 94158, USA
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Golden A. From phenologs to silent suppressors: Identifying potential therapeutic targets for human disease. Mol Reprod Dev 2017; 84:1118-1132. [PMID: 28834577 DOI: 10.1002/mrd.22880] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Accepted: 08/04/2017] [Indexed: 12/16/2022]
Abstract
Orthologous phenotypes, or phenologs, are seemingly unrelated phenotypes generated by mutations in a conserved set of genes. Phenologs have been widely observed and accepted by those who study model organisms, and allow one to study a set of genes in a model organism to learn more about the function of those genes in other organisms, including humans. At the cellular and molecular level, these conserved genes likely function in a very similar mode, but are doing so in different tissues or cell types and can result in different phenotypic effects. For example, the RAS-RAF-MEK-MAPK pathway in animals is a highly conserved signaling pathway that animals adopted for numerous biological processes, such as vulval induction in Caenorhabditis elegans and cell proliferation in mammalian cells; but this same gene set has been co-opted to function in a variety of cellular contexts. In this review, I give a few examples of how suppressor screens in model organisms (with a emphasis on C. elegans) can identify new genes that function in a conserved pathway in many other organisms. I also demonstrate how the identification of such genes can lead to important insights into mammalian biology. From such screens, an occasional silent suppressor that does not cause a phenotype on its own is found; such suppressors thus make for good candidates as therapeutic targets.
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Affiliation(s)
- Andy Golden
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
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UNC-18 and Tomosyn Antagonistically Control Synaptic Vesicle Priming Downstream of UNC-13 in Caenorhabditis elegans. J Neurosci 2017; 37:8797-8815. [PMID: 28821673 DOI: 10.1523/jneurosci.0338-17.2017] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2017] [Revised: 07/21/2017] [Accepted: 08/03/2017] [Indexed: 11/21/2022] Open
Abstract
Munc18-1/UNC-18 is believed to prime SNARE-mediated membrane fusion, yet the underlying mechanisms remain enigmatic. Here, we examine how potential gain-of-function mutations of Munc18-1/UNC-18 affect locomotory behavior and synaptic transmission, and how Munc18-1-mediated priming is related to Munc13-1/UNC-13 and Tomosyn/TOM-1, positive and negative SNARE regulators, respectively. We show that a Munc18-1(P335A)/UNC-18(P334A) mutation leads to significantly increased locomotory activity and acetylcholine release in Caenorhabditis elegans, as well as enhanced synaptic neurotransmission in cultured mammalian neurons. Importantly, similar to tom-1 null mutants, unc-18(P334A) mutants partially bypass the requirement of UNC-13. Moreover, unc-18(P334A) and tom-1 null mutations confer a strong synergy in suppressing the phenotypes of unc-13 mutants. Through biochemical experiments, we demonstrate that Munc18-1(P335A) exhibits enhanced activity in SNARE complex formation as well as in binding to the preformed SNARE complex, and partially bypasses the Munc13-1 requirement in liposome fusion assays. Our results indicate that Munc18-1/UNC-18 primes vesicle fusion downstream of Munc13-1/UNC-13 by templating SNARE complex assembly and acts antagonistically with Tomosyn/TOM-1.SIGNIFICANCE STATEMENT At presynaptic sites, SNARE-mediated membrane fusion is tightly regulated by several key proteins including Munc18/UNC-18, Munc13/UNC-13, and Tomosyn/TOM-1. However, how these proteins interact with each other to achieve the precise regulation of neurotransmitter release remains largely unclear. Using Caenorhabditis elegans as an in vivo model, we found that a gain-of-function mutant of UNC-18 increases locomotory activity and synaptic acetylcholine release, that it partially bypasses the requirement of UNC-13 for release, and that this bypass is synergistically augmented by the lack of TOM-1. We also elucidated the biochemical basis for the gain-of-function caused by this mutation. Thus, our study provides novel mechanistic insights into how Munc18/UNC-18 primes synaptic vesicle release and how this protein interacts functionally with Munc13/UNC-13 and Tomosyn/TOM-1.
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Ganner A, Neumann-Haefelin E. Genetic kidney diseases: Caenorhabditis elegans as model system. Cell Tissue Res 2017; 369:105-118. [PMID: 28484847 DOI: 10.1007/s00441-017-2622-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 03/31/2017] [Indexed: 12/18/2022]
Abstract
Despite its apparent simplicity, the nematode Caenorhabditis elegans has a high rating as a model in molecular and developmental biology and biomedical research. C. elegans has no excretory system comparable with the mammalian kidney but many of the genes and molecular pathways involved in human kidney diseases are conserved in C. elegans. The plethora of genetic, molecular and imaging tools available in C. elegans has enabled major discoveries in renal research and advanced our understanding of the pathogenesis of genetic kidney diseases. In particular, studies in C. elegans have pioneered the fundamental role of cilia for cystic kidney diseases. In addition, proteins of the glomerular filtration barrier and podocytes are critical for cell recognition, assembly of functional neuronal circuits, mechanosensation and signal transduction in C. elegans. C. elegans has also proved tremendously valuable for aging research and the Von Hippel-Lindau tumor suppressor gene has been shown to modulate lifespan in the nematode. Further, studies of the excretory canal, membrane transport and ion channel function in C. elegans have provided insights into mechanisms of tubulogenesis and cellular homeostasis. This review recounts the way that C. elegans can be used to investigate various aspects of genetic and molecular nephrology. This model system opens up an exciting and new area of study of renal development and diseases.
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Affiliation(s)
- Athina Ganner
- Department of Nephrology, Medical Center, University of Freiburg, Hugstetter Strasse 55, 79106 Freiburg, Germany
| | - Elke Neumann-Haefelin
- Department of Nephrology, Medical Center, University of Freiburg, Hugstetter Strasse 55, 79106 Freiburg, Germany.
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20
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Lemieux GA, Ashrafi K. Investigating Connections between Metabolism, Longevity, and Behavior in Caenorhabditis elegans. Trends Endocrinol Metab 2016; 27:586-596. [PMID: 27289335 PMCID: PMC4958586 DOI: 10.1016/j.tem.2016.05.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Revised: 05/18/2016] [Accepted: 05/19/2016] [Indexed: 01/19/2023]
Abstract
An overview of Caenorhabditis elegans as an experimental organism for studying energy balance is presented. Some of the unresolved questions that complicate the interpretation of lipid measurements from C. elegans are highlighted. We review studies that show that both lipid synthesis and lipid breakdown pathways are activated and needed for the longevity of hermaphrodites that lack their germlines. These findings illustrate the heterogeneity of triglyceride-rich lipid particles in C. elegans and reveal specific lipid signals that promote longevity. Finally, we provide a brief overview of feeding behavioral responses of C. elegans to varying nutritional conditions and highlight an unanticipated metabolic pathway that allows the incorporation of experience in feeding behavior.
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Affiliation(s)
| | - Kaveh Ashrafi
- University of California, San Francisco, San Francisco, CA, USA.
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21
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Hostelley TL, Lodh S, Zaghloul NA. Whole organism transcriptome analysis of zebrafish models of Bardet-Biedl Syndrome and Alström Syndrome provides mechanistic insight into shared and divergent phenotypes. BMC Genomics 2016; 17:318. [PMID: 27142762 PMCID: PMC4855444 DOI: 10.1186/s12864-016-2679-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 04/28/2016] [Indexed: 12/14/2022] Open
Abstract
Background Bardet-Biedl Syndrome (BBS) and Alström Syndrome are two pleiotropic ciliopathies with significant phenotypic overlap between them across many tissues. Although BBS and Alström genes are necessary for the proper function of primary cilia, their role in defects across multiple organ systems is unclear. Methods To provide insight into the pathways underlying BBS and Alström phenotypes, we carried out whole organism transcriptome analysis by RNA sequencing in established zebrafish models of the syndromes. Results We analyzed all genes that were significantly differentially expressed and found enrichment of phenotypically significant pathways in both models. These included multiple pathways shared between the two disease models as well as those unique to each model. Notably, we identified significant downregulation of genes in pathways relevant to visual system deficits and obesity in both disorders, consistent with those shared phenotypes. In contrast, neuronal pathways were significantly downregulated only in the BBS model but not in the Alström model. Our observations also suggested an important role for G-protein couple receptor and calcium signaling defects in both models. Discussion Pathway network analyses of both models indicate that visual system defects may be driven by genetic mechanisms independent of other phenotypes whereas the majority of other phenotypes are a result of genetic players that contribute to multiple pathways simultaneously. Additionally, examination of genes differentially expressed in opposing directions between the two models suggest a deficit in pancreatic function in the Alström model, that is not present in the BBS model. Conclusions These findings provide important novel insight into shared and divergent phenotypes between two similar but distinct genetic syndromes. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-2679-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Timothy L Hostelley
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, 660 W. Redwood Street, Howard Hall 487, Baltimore, MD, 21201, USA
| | - Sukanya Lodh
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, 660 W. Redwood Street, Howard Hall 487, Baltimore, MD, 21201, USA
| | - Norann A Zaghloul
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, 660 W. Redwood Street, Howard Hall 487, Baltimore, MD, 21201, USA.
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22
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Witham E, Comunian C, Ratanpal H, Skora S, Zimmer M, Srinivasan S. C. elegans Body Cavity Neurons Are Homeostatic Sensors that Integrate Fluctuations in Oxygen Availability and Internal Nutrient Reserves. Cell Rep 2016; 14:1641-1654. [PMID: 26876168 DOI: 10.1016/j.celrep.2016.01.052] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 12/16/2015] [Accepted: 01/14/2016] [Indexed: 12/28/2022] Open
Abstract
It is known that internal physiological state, or interoception, influences CNS function and behavior. However, the neurons and mechanisms that integrate sensory information with internal physiological state remain largely unknown. Here, we identify C. elegans body cavity neurons called URX(L/R) as central homeostatic sensors that integrate fluctuations in oxygen availability with internal metabolic state. We show that depletion of internal body fat reserves increases the tonic activity of URX neurons, which influences the magnitude of the evoked sensory response to oxygen. These responses are integrated via intracellular cGMP and Ca(2+). The extent of neuronal activity thus reflects the balance between the perception of oxygen and available fat reserves. The URX homeostatic sensor ensures that neural signals that stimulate fat loss are only deployed when there are sufficient fat reserves to do so. Our results uncover an interoceptive neuroendocrine axis that relays internal state information to the nervous system.
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Affiliation(s)
- Emily Witham
- Department of Chemical Physiology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA; Dorris Neuroscience Center, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Claudio Comunian
- Department of Chemical Physiology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Harkaranveer Ratanpal
- Department of Chemical Physiology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA; Dorris Neuroscience Center, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | - Susanne Skora
- Research Institute of Molecular Pathology IMP, Vienna Biocenter VBC, Dr. Bohr-Gasse 7, 1030 Vienna, Austria
| | - Manuel Zimmer
- Research Institute of Molecular Pathology IMP, Vienna Biocenter VBC, Dr. Bohr-Gasse 7, 1030 Vienna, Austria
| | - Supriya Srinivasan
- Department of Chemical Physiology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA; Dorris Neuroscience Center, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
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Seidel HS, Kimble J. Cell-cycle quiescence maintains Caenorhabditis elegans germline stem cells independent of GLP-1/Notch. eLife 2015; 4. [PMID: 26551561 PMCID: PMC4718729 DOI: 10.7554/elife.10832] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 11/07/2015] [Indexed: 12/13/2022] Open
Abstract
Many types of adult stem cells exist in a state of cell-cycle quiescence, yet it has remained unclear whether quiescence plays a role in maintaining the stem cell fate. Here we establish the adult germline of Caenorhabditis elegans as a model for facultative stem cell quiescence. We find that mitotically dividing germ cells--including germline stem cells--become quiescent in the absence of food. This quiescence is characterized by a slowing of S phase, a block to M-phase entry, and the ability to re-enter M phase rapidly in response to re-feeding. Further, we demonstrate that cell-cycle quiescence alters the genetic requirements for stem cell maintenance: The signaling pathway required for stem cell maintenance under fed conditions--GLP-1/Notch signaling--becomes dispensable under conditions of quiescence. Thus, cell-cycle quiescence can itself maintain stem cells, independent of the signaling pathway otherwise essential for such maintenance.
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Affiliation(s)
- Hannah S Seidel
- Department of Biochemistry, University of Wisconsin-Madison, Madison, United States.,The Ellison Medical Foundation Fellow of the Life Sciences Research Foundation, The Lawrence Ellison Foundation, Mount Airy, United States
| | - Judith Kimble
- Department of Biochemistry, University of Wisconsin-Madison, Madison, United States.,Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, United States
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Yee LE, Garcia-Gonzalo FR, Bowie RV, Li C, Kennedy JK, Ashrafi K, Blacque OE, Leroux MR, Reiter JF. Conserved Genetic Interactions between Ciliopathy Complexes Cooperatively Support Ciliogenesis and Ciliary Signaling. PLoS Genet 2015; 11:e1005627. [PMID: 26540106 PMCID: PMC4635004 DOI: 10.1371/journal.pgen.1005627] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 10/05/2015] [Indexed: 11/18/2022] Open
Abstract
Mutations in genes encoding cilia proteins cause human ciliopathies, diverse disorders affecting many tissues. Individual genes can be linked to ciliopathies with dramatically different phenotypes, suggesting that genetic modifiers may participate in their pathogenesis. The ciliary transition zone contains two protein complexes affected in the ciliopathies Meckel syndrome (MKS) and nephronophthisis (NPHP). The BBSome is a third protein complex, affected in the ciliopathy Bardet-Biedl syndrome (BBS). We tested whether mutations in MKS, NPHP and BBS complex genes modify the phenotypic consequences of one another in both C. elegans and mice. To this end, we identified TCTN-1, the C. elegans ortholog of vertebrate MKS complex components called Tectonics, as an evolutionarily conserved transition zone protein. Neither disruption of TCTN-1 alone or together with MKS complex components abrogated ciliary structure in C. elegans. In contrast, disruption of TCTN-1 together with either of two NPHP complex components, NPHP-1 or NPHP-4, compromised ciliary structure. Similarly, disruption of an NPHP complex component and the BBS complex component BBS-5 individually did not compromise ciliary structure, but together did. As in nematodes, disrupting two components of the mouse MKS complex did not cause additive phenotypes compared to single mutants. However, disrupting both Tctn1 and either Nphp1 or Nphp4 exacerbated defects in ciliogenesis and cilia-associated developmental signaling, as did disrupting both Tctn1 and the BBSome component Bbs1. Thus, we demonstrate that ciliary complexes act in parallel to support ciliary function and suggest that human ciliopathy phenotypes are altered by genetic interactions between different ciliary biochemical complexes. Ciliopathies, diseases arising from defects in the functions of primary cilia, have many different manifestations and vary dramatically in severity. How genetics influence ciliopathy phenotypes is poorly understood. Building off of our increasing knowledge of how different biochemical complexes contribute to ciliary function, we investigated how ciliopathy-associated genes interact to support ciliogenesis. Using a combination of nematode and mouse genetics, we found that genes encoding components of different biochemical complexes interact, whereas genes encoding different components within a single complex do not. These results revealed overlapping ciliary functions of biochemically distinct proteins complexes such as the BBSome, the transition zone MKS complex and the transition zone NPHP complex. This work indicates the genetic interactions that may alter the phenotypic consequences of human ciliopathy mutations.
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Affiliation(s)
- Laura E. Yee
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California, United States of America
| | - Francesc R. Garcia-Gonzalo
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California, United States of America
| | - Rachel V. Bowie
- School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Belfield, Dublin, Ireland
| | - Chunmei Li
- Department of Molecular Biology and Biochemistry and Centre for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Julie K. Kennedy
- School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Belfield, Dublin, Ireland
| | - Kaveh Ashrafi
- Department of Physiology, University of California, San Francisco, San Francisco, California, United States of America
| | - Oliver E. Blacque
- School of Biomolecular and Biomedical Science, UCD Conway Institute, University College Dublin, Belfield, Dublin, Ireland
| | - Michel R. Leroux
- Department of Molecular Biology and Biochemistry and Centre for Cell Biology, Development, and Disease, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Jeremy F. Reiter
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California, United States of America
- * E-mail:
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Lodh S, Hostelley TL, Leitch CC, O'Hare EA, Zaghloul NA. Differential effects on β-cell mass by disruption of Bardet-Biedl syndrome or Alstrom syndrome genes. Hum Mol Genet 2015; 25:57-68. [PMID: 26494903 DOI: 10.1093/hmg/ddv447] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 10/20/2015] [Indexed: 12/15/2022] Open
Abstract
Rare genetic syndromes characterized by early-onset type 2 diabetes have revealed the importance of pancreatic β-cells in genetic susceptibility to diabetes. However, the role of genetic regulation of β-cells in disorders that are also characterized by highly penetrant obesity, a major additional risk factor, is unclear. In this study, we investigated the contribution of genes associated with two obesity ciliopathies, Bardet-Biedl Syndrome and Alstrom Syndrome, to the production and maintenance of pancreatic β-cells. Using zebrafish models of these syndromes, we identified opposing effects on production of β-cells. Loss of the Alstrom gene, alms1, resulted in a significant decrease in β-cell production whereas loss of BBS genes, bbs1 or bbs4, resulted in a significant increase. Examination of the regulatory program underlying β-cell production suggested that these effects were specific to β-cells. In addition to the initial production of β-cells, we observed significant differences in their continued maintenance. Under prolonged exposure to high glucose conditions, alms1-deficient β-cells were unable to continually expand as a result of decreased proliferation and increased cell death. Although bbs1-deficient β-cells were similarly susceptible to apoptosis, the overall maintenance of β-cell number in those animals was sustained likely due to increased proliferation. Taken together, these findings implicate discrepant production and maintenance of β-cells in the differential susceptibility to diabetes found between these two genetic syndromes.
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Affiliation(s)
- Sukanya Lodh
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD USA
| | - Timothy L Hostelley
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD USA
| | - Carmen C Leitch
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD USA
| | - Elizabeth A O'Hare
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD USA
| | - Norann A Zaghloul
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD USA
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Abstract
The compact nervous system of Caenorhabditis elegans and its genetic tractability are features that make this organism highly suitable for investigating energy balance in an animal system. Here, we focus on molecular components and organizational principles emerging from the investigation of pathways that largely originate in the nervous system and regulate feeding behavior but also peripheral fat regulation through neuroendocrine signaling. We provide an overview of studies aimed at understanding how C. elegans integrate internal and external cues in feeding behavior. We highlight some of the similarities and differences in energy balance between C. elegans and mammals. We also provide our perspective on unresolved issues, both conceptual and technical, that we believe have hampered critical evaluation of findings relevant to fat regulation in C. elegans.
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Affiliation(s)
- George A Lemieux
- Department of Physiology, University of California, San Francisco, California 94158;
| | - Kaveh Ashrafi
- Department of Physiology, University of California, San Francisco, California 94158;
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27
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Abstract
OBJECTIVE The purpose of this study is to present a clinical report of a patient with Bardet-Biedl syndrome, aiming to help the dentist to identify the general aspects, systemic changes, alterations. CLINICAL REPORT Bardet-Biedl syndrome is defined as a genetic disorder of autosomal recessive condition; this case is a male patient, 20 years old. The general features presented by the patient were strabismus, polydactyly, hypogonadism, obesity, cognitive impairment, and autistic behavior. Dentally, this patient presents with hypotonic face, high-arched palate, dental crowding, unilateral crossbite, and difficulty in cleaning but with good-quality oral health. CONCLUSIONS Many patients with this syndrome have compromised oral hygiene, difficulty in addressing dental cases, developmental delay, and autistic behavior. Thus, it is important to pay attention to these early children from an early age and encourage preventive approach.
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28
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Lemieux GA, Cunningham KA, Lin L, Mayer F, Werb Z, Ashrafi K. Kynurenic acid is a nutritional cue that enables behavioral plasticity. Cell 2015; 160:119-31. [PMID: 25594177 PMCID: PMC4334586 DOI: 10.1016/j.cell.2014.12.028] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 10/16/2014] [Accepted: 12/11/2014] [Indexed: 12/27/2022]
Abstract
The kynurenine pathway of tryptophan metabolism is involved in the pathogenesis of several brain diseases, but its physiological functions remain unclear. We report that kynurenic acid, a metabolite in this pathway, functions as a regulator of food-dependent behavioral plasticity in C. elegans. The experience of fasting in C. elegans alters a variety of behaviors, including feeding rate, when food is encountered post-fast. Levels of neurally produced kynurenic acid are depleted by fasting, leading to activation of NMDA-receptor-expressing interneurons and initiation of a neuropeptide-y-like signaling axis that promotes elevated feeding through enhanced serotonin release when animals re-encounter food. Upon refeeding, kynurenic acid levels are eventually replenished, ending the elevated feeding period. Because tryptophan is an essential amino acid, these findings suggest that a physiological role of kynurenic acid is in directly linking metabolism to activity of NMDA and serotonergic circuits, which regulate a broad range of behaviors and physiologies.
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Affiliation(s)
- George A Lemieux
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158-2240, USA
| | - Katherine A Cunningham
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158-2240, USA
| | - Lin Lin
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158-2240, USA
| | - Fahima Mayer
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158-2240, USA
| | - Zena Werb
- Department of Anatomy, University of California, San Francisco, San Francisco, CA 94143-0452, USA
| | - Kaveh Ashrafi
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158-2240, USA.
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29
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Oh EC, Vasanth S, Katsanis N. Metabolic regulation and energy homeostasis through the primary Cilium. Cell Metab 2015; 21:21-31. [PMID: 25543293 PMCID: PMC4370781 DOI: 10.1016/j.cmet.2014.11.019] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Revised: 09/19/2014] [Accepted: 11/20/2014] [Indexed: 02/07/2023]
Abstract
Obesity and diabetes represent a significant healthcare concern. In contrast to genome-wide association studies that, some exceptions notwithstanding, have offered modest clues about pathomechanism, the dissection of rare disorders in which obesity represents a core feature have highlighted key molecules and structures critical to energy regulation. Here we focus on the primary cilium, an organelle whose roles in energy homeostasis have been underscored by the high incidence of obesity and type II diabetes in patients and mouse mutants with compromised ciliary function. We discuss recent evidence linking ciliary dysfunction to metabolic defects and we explore the contribution of neuronal and nonneuronal cilia to these phenotypes.
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Affiliation(s)
- Edwin C Oh
- Center for Human Disease Modeling, Duke University School of Medicine, Durham, NC 27710, USA.
| | - Shivakumar Vasanth
- Center for Human Disease Modeling, Duke University School of Medicine, Durham, NC 27710, USA
| | - Nicholas Katsanis
- Center for Human Disease Modeling, Duke University School of Medicine, Durham, NC 27710, USA.
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30
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Braunreiter K, Hamlin S, Lyman-Gingerich J. Identification and characterization of a novel allele of Caenorhabditis elegans bbs-7. PLoS One 2014; 9:e113737. [PMID: 25486278 PMCID: PMC4259304 DOI: 10.1371/journal.pone.0113737] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Accepted: 10/29/2014] [Indexed: 01/25/2023] Open
Abstract
Primary cilia play a role in the sensation of and response to the surrounding environment. Caenorhabditis elegans (C. elegans) have primary cilia only on the distal tips of some dendrites. In order to better understand the relationship between receptor localization to cilia, cilia structure and cilia function, we have characterized a mutation originally identified in a forward genetic screen for mutants with defective PKD-2 ciliary localization. Through behavioral assays and examination of the structure of cilia in the cil-5 (my13) mutant animals, we have found that my13 disrupts not only receptor localization, but also some cilia-mediated sensory behaviors and cilia structural integrity. We have identified the my13 lesion and found that it is a missense mutation in bbs-7, an ortholog of human BBS-7, a gene known to affect human cilia and to be involved in Bardet-Biedl syndrome. Finally, we show that bbs-7(my13) also affects the glia cells which support the cilia.
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Affiliation(s)
- Kara Braunreiter
- Department of Biology, University of Wisconsin-Eau Claire, Phillips Hall 330, Eau Claire, Wisconsin, United States of America
| | - Shelby Hamlin
- Department of Biology, University of Wisconsin-Eau Claire, Phillips Hall 330, Eau Claire, Wisconsin, United States of America
| | - Jamie Lyman-Gingerich
- Department of Biology, University of Wisconsin-Eau Claire, Phillips Hall 330, Eau Claire, Wisconsin, United States of America
- * E-mail:
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31
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Ciliary dysfunction impairs beta-cell insulin secretion and promotes development of type 2 diabetes in rodents. Nat Commun 2014; 5:5308. [PMID: 25374274 DOI: 10.1038/ncomms6308] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Accepted: 09/18/2014] [Indexed: 11/08/2022] Open
Abstract
Type 2 diabetes mellitus is affecting more than 382 million people worldwide. Although much progress has been made, a comprehensive understanding of the underlying disease mechanism is still lacking. Here we report a role for the β-cell primary cilium in type 2 diabetes susceptibility. We find impaired glucose handling in young Bbs4(-/-) mice before the onset of obesity. Basal body/ciliary perturbation in murine pancreatic islets leads to impaired first phase insulin release ex and in vivo. Insulin receptor is recruited to the cilium of stimulated β-cells and ciliary/basal body integrity is required for activation of downstream targets of insulin signalling. We also observe a reduction in the number of ciliated β-cells along with misregulated ciliary/basal body gene expression in pancreatic islets in a diabetic rat model. We suggest that ciliary function is implicated in insulin secretion and insulin signalling in the β-cell and that ciliary dysfunction could contribute to type 2 diabetes susceptibility.
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32
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Lemieux GA, Ashrafi K. Insights and challenges in using C. elegans for investigation of fat metabolism. Crit Rev Biochem Mol Biol 2014; 50:69-84. [PMID: 25228063 DOI: 10.3109/10409238.2014.959890] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
C. elegans provides a genetically tractable system for deciphering the homeostatic mechanisms that underlie fat regulation in intact organisms. Here, we provide an overview of the recent advances in the C. elegans fat field with particular attention to studies of C. elegans lipid droplets, the complex links between lipases, autophagy, and lifespan, and analyses of key transcriptional regulatory mechanisms that coordinate lipid homeostasis. These studies demonstrate the ancient origins of mammalian and C. elegans fat regulatory pathways and highlight how C. elegans is being used to identify and analyze novel lipid pathways that are then shown to function similarly in mammals. Despite its many advantages, study of fat regulation in C. elegans is currently faced with a number of conceptual and methodological challenges. We critically evaluate some of the assumptions in the field and highlight issues that we believe should be taken into consideration when interpreting lipid content data in C. elegans.
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Affiliation(s)
- George A Lemieux
- Department of Physiology, University of California , San Francisco, CA , USA
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33
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Cunningham KA, Bouagnon AD, Barros AG, Lin L, Malard L, Romano-Silva MA, Ashrafi K. Loss of a neural AMP-activated kinase mimics the effects of elevated serotonin on fat, movement, and hormonal secretions. PLoS Genet 2014; 10:e1004394. [PMID: 24921650 PMCID: PMC4055570 DOI: 10.1371/journal.pgen.1004394] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 04/07/2014] [Indexed: 12/30/2022] Open
Abstract
AMP-activated protein kinase (AMPK) is an evolutionarily conserved master regulator of metabolism and a therapeutic target in type 2 diabetes. As an energy sensor, AMPK activity is responsive to both metabolic inputs, for instance the ratio of AMP to ATP, and numerous hormonal cues. As in mammals, each of two genes, aak-1 and aak-2, encode for the catalytic subunit of AMPK in C. elegans. Here we show that in C. elegans loss of aak-2 mimics the effects of elevated serotonin signaling on fat reduction, slowed movement, and promoting exit from dauer arrest. Reconstitution of aak-2 in only the nervous system restored wild type fat levels and movement rate to aak-2 mutants and reconstitution in only the ASI neurons was sufficient to significantly restore dauer maintenance to the mutant animals. As in elevated serotonin signaling, inactivation of AAK-2 in the ASI neurons caused enhanced secretion of dense core vesicles from these neurons. The ASI neurons are the site of production of the DAF-7 TGF-β ligand and the DAF-28 insulin, both of which are secreted by dense core vesicles and play critical roles in whether animals stay in dauer or undergo reproductive development. These findings show that elevated levels of serotonin promote enhanced secretions of systemic regulators of pro-growth and differentiation pathways through inactivation of AAK-2. As such, AMPK is not only a recipient of hormonal signals but can also be an upstream regulator. Our data suggest that some of the physiological phenotypes previously attributed to peripheral AAK-2 activity on metabolic targets may instead be due to the role of this kinase in neural serotonin signaling.
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Affiliation(s)
- Katherine A. Cunningham
- Department of Physiology, University of California, San Francisco, San Francisco, California, United States of America
| | - Aude D. Bouagnon
- Department of Physiology, University of California, San Francisco, San Francisco, California, United States of America
| | - Alexandre G. Barros
- Instituto Nacional de Ciência e Tecnologia de Medicina Molecular, Faculdade de Medicina da Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Lin Lin
- Department of Physiology, University of California, San Francisco, San Francisco, California, United States of America
| | - Leandro Malard
- Departamento de Física, Instituto de Ciências Exatas da Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Marco Aurélio Romano-Silva
- Instituto Nacional de Ciência e Tecnologia de Medicina Molecular, Faculdade de Medicina da Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Kaveh Ashrafi
- Department of Physiology, University of California, San Francisco, San Francisco, California, United States of America
- * E-mail:
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34
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Lodh S, O’Hare EA, Zaghloul NA. Primary cilia in pancreatic development and disease. BIRTH DEFECTS RESEARCH. PART C, EMBRYO TODAY : REVIEWS 2014; 102:139-58. [PMID: 24864023 PMCID: PMC4213238 DOI: 10.1002/bdrc.21063] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Revised: 03/30/2014] [Accepted: 03/30/2014] [Indexed: 01/04/2023]
Abstract
Primary cilia and their anchoring basal bodies are important regulators of a growing list of signaling pathways. Consequently, dysfunction in proteins associated with these structures results in perturbation of the development and function of a spectrum of tissue and cell types. Here, we review the role of cilia in mediating the development and function of the pancreas. We focus on ciliary regulation of major pathways involved in pancreatic development, including Shh, Wnt, TGF-β, Notch, and fibroblast growth factor. We also discuss pancreatic phenotypes associated with ciliary dysfunction, including pancreatic cysts and defects in glucose homeostasis, and explore the potential role of cilia in such defects.
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Affiliation(s)
- Sukanya Lodh
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
| | - Elizabeth A. O’Hare
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
| | - Norann A. Zaghloul
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland
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35
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Safra M, Henis-Korenblit S. A new tool in C. elegans reveals changes in secretory protein metabolism in ire-1-deficient animals. WORM 2014; 3:e27733. [PMID: 25191629 PMCID: PMC4152325 DOI: 10.4161/worm.27733] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 12/15/2013] [Accepted: 01/03/2014] [Indexed: 12/24/2022]
Abstract
We recently showed that the ire-1/xbp-1 arm of the UPR plays a crucial role in maintaining basic endoplasmic reticulum (ER) functions required for the metabolism of secreted proteins even during unstressed growth conditions. During these studies we realized that although C. elegans is a powerful system to study the genetics of many cellular processes; it lacks effective tools for tracking the metabolism of secreted proteins at the cell and organism levels. Here, we outline how genetic manipulations and expression analysis of a DAF-28::GFP translational fusion transgene can be combined to infer different steps in the life cycle of secretory proteins. We demonstrate how we have used this tool to reveal folding defects, clearance defects, and secretion defects in ire-1 and xbp-1 mutants. We believe that further studies using this tool will deepen the understanding of secretory protein metabolism.
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Affiliation(s)
- Modi Safra
- The Mina and Everard Goodman Faculty of Life Sciences; Bar-Ilan University; Ramat Gan, Israel
| | - Sivan Henis-Korenblit
- The Mina and Everard Goodman Faculty of Life Sciences; Bar-Ilan University; Ramat Gan, Israel
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36
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Lin C, Theodorides ML, McDaniel AH, Tordoff MG, Zhang Q, Li X, Bosak N, Bachmanov AA, Reed DR. QTL analysis of dietary obesity in C57BL/6byj X 129P3/J F2 mice: diet- and sex-dependent effects. PLoS One 2013; 8:e68776. [PMID: 23922663 PMCID: PMC3726688 DOI: 10.1371/journal.pone.0068776] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2012] [Accepted: 06/05/2013] [Indexed: 11/25/2022] Open
Abstract
Obesity is a heritable trait caused by complex interactions between genes and environment, including diet. Gene-by-diet interactions are difficult to study in humans because the human diet is hard to control. Here, we used mice to study dietary obesity genes, by four methods. First, we bred 213 F2 mice from strains that are susceptible [C57BL/6ByJ (B6)] or resistant [129P3/J (129)] to dietary obesity. Percent body fat was assessed after mice ate low-energy diet and again after the same mice ate high-energy diet for 8 weeks. Linkage analyses identified QTLs associated with dietary obesity. Three methods were used to filter candidate genes within the QTL regions: (a) association mapping was conducted using >40 strains; (b) differential gene expression and (c) comparison of genomic DNA sequence, using two strains closely related to the progenitor strains from Experiment 1. The QTL effects depended on whether the mice were male or female or which diet they were recently fed. After feeding a low-energy diet, percent body fat was linked to chr 7 (LOD = 3.42). After feeding a high-energy diet, percent body fat was linked to chr 9 (Obq5; LOD = 3.88), chr 12 (Obq34; LOD = 3.88), and chr 17 (LOD = 4.56). The Chr 7 and 12 QTLs were sex dependent and all QTL were diet-dependent. The combination of filtering methods highlighted seven candidate genes within the QTL locus boundaries: Crx, Dmpk, Ahr, Mrpl28, Glo1, Tubb5, and Mut. However, these filtering methods have limitations so gene identification will require alternative strategies, such as the construction of congenics with very small donor regions.
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Affiliation(s)
- Cailu Lin
- Monell Chemical Senses Center, Philadelphia Pennsylvania, United States of America
| | - Maria L. Theodorides
- Monell Chemical Senses Center, Philadelphia Pennsylvania, United States of America
| | - Amanda H. McDaniel
- Monell Chemical Senses Center, Philadelphia Pennsylvania, United States of America
| | - Michael G. Tordoff
- Monell Chemical Senses Center, Philadelphia Pennsylvania, United States of America
| | - Qinmin Zhang
- Monell Chemical Senses Center, Philadelphia Pennsylvania, United States of America
| | - Xia Li
- Monell Chemical Senses Center, Philadelphia Pennsylvania, United States of America
| | - Natalia Bosak
- Monell Chemical Senses Center, Philadelphia Pennsylvania, United States of America
| | | | - Danielle R. Reed
- Monell Chemical Senses Center, Philadelphia Pennsylvania, United States of America
- * E-mail:
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37
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Zhang Q, Nishimura D, Vogel T, Shao J, Swiderski R, Yin T, Searby C, Carter CS, Kim G, Bugge K, Stone EM, Sheffield VC. BBS7 is required for BBSome formation and its absence in mice results in Bardet-Biedl syndrome phenotypes and selective abnormalities in membrane protein trafficking. J Cell Sci 2013; 126:2372-80. [PMID: 23572516 DOI: 10.1242/jcs.111740] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Bardet-Biedl Syndrome (BBS) is a pleiotropic and genetically heterozygous disorder caused independently by numerous genes (BBS1-BBS17). Seven highly conserved BBS proteins (BBS1, 2, 4, 5, 7, 8 and 9) form a complex known as the BBSome, which functions in ciliary membrane biogenesis. BBS7 is both a unique subunit of the BBSome and displays direct physical interaction with a second BBS complex, the BBS chaperonin complex. To examine the in vivo function of BBS7, we generated Bbs7 knockout mice. Bbs7(-/-) mice show similar phenotypes to other BBS gene mutant mice including retinal degeneration, obesity, ventriculomegaly and male infertility characterized by abnormal spermatozoa flagellar axonemes. Using tissues from Bbs7(-/-) mice, we show that BBS7 is required for BBSome formation, and that BBS7 and BBS2 depend on each other for protein stability. Although the BBSome serves as a coat complex for ciliary membrane proteins, BBS7 is not required for the localization of ciliary membrane proteins polycystin-1, polycystin-2, or bitter taste receptors, but absence of BBS7 leads to abnormal accumulation of the dopamine D1 receptor to the ciliary membrane, indicating that BBS7 is involved in specific membrane protein localization to cilia.
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Affiliation(s)
- Qihong Zhang
- Department of Pediatrics, Howard Hughes Medical Institute, University of Iowa, Iowa City, IA 52242, USA
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