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Sakai Y, Okabe Y, Itai G, Shiozawa S. An efficient evaluation system for factors affecting the genome editing efficiency in mouse. Exp Anim 2023; 72:526-534. [PMID: 37407493 PMCID: PMC10658088 DOI: 10.1538/expanim.23-0045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 06/23/2023] [Indexed: 07/07/2023] Open
Abstract
Genome editing technology is widely used in the field of laboratory animal science for the production of genetic disease models and the analysis of gene function. One of the major technical problems in genome editing is the low efficiency of precise knock-in by homologous recombination compared to simple knockout via non-homologous end joining. Many studies have focused on this issue, and various solutions have been proposed; however, they have yet to be fully resolved. In this study, we established a system that can easily determine the genotype at the mouse (Mus musculus) Tyr gene locus for genome editing both in vitro and in vivo. In this genome editing system, by designing the Cas9 cleavage site and donor template, wild-type, knockout, and knock-in genotypes can be distinguished by restriction fragment length polymorphisms of PCR products. Moreover, the introduction of the H420R mutation in tyrosinase allows the determination of knock-in mice with specific coat color patterns. Using this system, we evaluated the effects of small-molecule compounds on the efficiency of genome editing in mouse embryos. Consequently, we successfully identified a small-molecule compound that improves knock-in efficiency in genome editing in mouse embryos. Thus, this genome editing system is suitable for screening compounds that can improve knock-in efficiency.
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Affiliation(s)
- Yusuke Sakai
- Institute for Disease Modeling, Kurume University School of Medicine, 67 Asahimachi, Kurume city, Fukuoka 830-0011, Japan
| | - Yuri Okabe
- Institute for Disease Modeling, Kurume University School of Medicine, 67 Asahimachi, Kurume city, Fukuoka 830-0011, Japan
| | - Gen Itai
- Center for Integrated Medical Research, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
- JAC Inc., 1-2-7 Higashiyama, Meguro-ku, Tokyo 153-0043, Japan
| | - Seiji Shiozawa
- Institute for Disease Modeling, Kurume University School of Medicine, 67 Asahimachi, Kurume city, Fukuoka 830-0011, Japan
- Center for Integrated Medical Research, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan
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2
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3
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Affiliation(s)
- I J Jackson
- MRC Human Genetics Unit, Western General Hospital, Crewe Road, Edinburgh, EH4 2XU, UK
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4
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Jerez-Timaure NC, Kearney F, Simpson EB, Eisen EJ, Pomp D. Characterization of QTL with major effects on fatness and growth on mouse chromosome 2. ACTA ACUST UNITED AC 2005; 12:1408-20. [PMID: 15483205 DOI: 10.1038/oby.2004.177] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE To isolate and characterize a region on mouse chromosome 2 harboring quantitative trait loci with large influences on growth and fatness. RESEARCH METHODS AND PROCEDURES A congenic line [M16i.B6-(D2Mit306-D2Mit52); MB2] was created using the polygenic obese M16i selection line as the recipient for an approximately 38-centimorgan region from C57BL/6J. Males and females from M16i and MB2 were compared for body weight, body composition, feed consumption, and additional traits at 6, 15, and 24 weeks. Interactions of genotype and environment (low and high dietary fat) were investigated. Males (8 weeks) were evaluated for fatty acid profiles in liver and for transcriptional profiles in liver and adipose. RESULTS Consequences of replacing M16i alleles with C57BL/6J alleles in MB2 were maximized at 15 weeks. MB2 mice were up to 15% lighter than M16i at this age, with no differences in feed consumption. As a percentage of body weight, MB2 had dramatically less epididymal (males) or perimetrial (females) fat (1.17% vs. 2.79% pooled across sex) and lower total lipids (16.1% vs. 23.3%) than M16i. Decreased adiposity in MB2 was not dependent on gender or diet. MB2 mice also had significant decreases in levels of leptin, insulin, and glucose, decreased de novo synthesis of hepatic fatty acid, and transcriptional changes for many genes both within, and external to, the congenic region. DISCUSSION Results confirm the presence and large effects of mouse chromosome 2 quantitative trait loci and further define their phenotypic consequences related to energy balance. The MB2 congenic line is a powerful resource for eventual identification of pathways and mutations within genes regulating predisposition to growth and obesity.
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5
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Abstract
Differences in skin and hair color are principally genetically determined and are due to variation in the amount, type, and packaging of melanin polymers produced by melanocytes secreted into keratinocytes. Pigmentary phenotype is genetically complex and at a physiological level complicated. Genes determining a number of rare Mendelian disorders of pigmentation such as albinism have been identified, but only one gene, the melanocortin 1 receptor (MCR1), has so far been identified to explain variation in the normal population such as that leading to red hair, freckling, and sun-sensitivity. Genotype-phenotype relations of the MC1R are reviewed, as well as methods to improve the phenotypic assessment of human pigmentary status. It is argued that given advances in model systems, increases in technical facility, and the lower cost of genotype assessment, the lack of standardized phenotype assessment is now a major limit on advance.
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Affiliation(s)
- Jonathan L Rees
- Systems Group, Dermatology, University of Edinburgh, Lauriston Buildings, Lauriston Place, Edinburgh, EH3 9YW, United Kingdom.
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6
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Abstract
Red hair is one of the most striking variants of human hair coloration and has historically been of profound social importance. Red hair in man is due to certain loss of function mutations of one of the peptide products of the pro-opiomelanocortin (POMC) gene, the melanocortin-1 receptor (MC1R, MIM 155555). Such functional mutations enable the melanocyte to produce red-yellow pheomelanin in preference to the default, black-brown eumelanin. This paper reviews the path of discovery of the MC1R in control of animal coat colour, the subsequent role of MC1R in human physiology and possibly wider role of MC1R in human skin carcinogenesis and human development through history.
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Affiliation(s)
- Thomas Ha
- Department of Dermatology, University of Edinburgh, Edinburgh, UK.
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7
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Alhaidari, Olivry, Ortonne. Melanocytogenesis and melanogenesis: genetic regulation and comparative clinical diseases. Vet Dermatol 2002; 10:3-16. [DOI: 10.1046/j.1365-3164.1999.00132.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Alhaidari
- Clinique Vétérinaire, Cidex 248, R. N. 85, 06330‐Roquefort les Pins, France,
| | - Olivry
- College of Veterinary Medicine, North Carolina State University, 4700 Hillsborough street, Raleigh, NC 27606, USA,
| | - Ortonne
- Hopital de l’Archet II‐Service de Dermatologie, 151, route Saint Antoine de Ginestière‐BP 79, 06202 Nice Cedex 3, France
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8
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Matesic LE, Yip R, Reuss AE, Swing DA, O'Sullivan TN, Fletcher CF, Copeland NG, Jenkins NA. Mutations in Mlph, encoding a member of the Rab effector family, cause the melanosome transport defects observed in leaden mice. Proc Natl Acad Sci U S A 2001; 98:10238-43. [PMID: 11504925 PMCID: PMC56945 DOI: 10.1073/pnas.181336698] [Citation(s) in RCA: 192] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The d, ash, and ln coat color mutations provide a unique model system for the study of vesicle transport in mammals. All three mutant loci encode genes that are required for the polarized transport of melanosomes, the specialized, pigment-containing organelles of melanocytes, to the neighboring keratinocytes and eventually into coat hairs. Genetic studies suggest that these genes function in the same or overlapping pathways and are supported by biochemical studies showing that d encodes an actin-based melanosome transport motor, MyoVa, whereas ash encodes Rab27a, a protein that localizes to the melanosome and is postulated to serve as the MyoVa receptor. Here we show that ln encodes melanophilin (Mlph), a previously undescribed protein with homology to Rab effectors such as granuphilin, Slp3-a, and rabphilin-3A. Like all of these effectors, Mlph possesses two Zn(2+)-binding CX(2)CX(13,14)CX(2)C motifs and a short aromatic-rich amino acid region that is critical for Rab binding. However, Mlph does not contain the two Ca(2+)-binding C(2) domains found in these and other proteins involved in vesicle transport, suggesting that it represents a previously unrecognized class of Rab effectors. Collectively, our data show that Mlph is a critical component of the melanosome transport machinery and suggest that Mlph might function as part of a transport complex with Rab27a and MyoVa.
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Affiliation(s)
- L E Matesic
- Mouse Cancer Genetics Program, National Cancer Institute, Frederick, MD 21702, USA
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9
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Xue B, Zemel MB. Relationship between human adipose tissue agouti and fatty acid synthase (FAS). J Nutr 2000; 130:2478-81. [PMID: 11015476 DOI: 10.1093/jn/130.10.2478] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The human homologue of the murine obesity gene, agouti, is expressed in adipose tissue. We have shown that recombinant agouti protein regulates adipocyte lipogenesis and lipolysis coordinately and promotes lipid storage via a Ca(2+)-dependent mechanism in vitro, which may contribute to agouti-induced obesity. However, little is known about agouti's physiologic function in humans. We first studied the agouti content in human mature adipocytes vs. preadipocytes. The agouti content of human mature adipocytes was five times as abundant as in preadipocytes (19.18 +/- 2.46 vs. 4.07 +/- 0.51 pg/microg protein, P: < 0.005), suggesting that agouti is up-regulated during adipocyte differentiation. We next studied the relationship of agouti mRNA and protein to fatty acid synthase (FAS) mRNA and activity in adipose tissue obtained from nonobese and mildly obese patients (body mass index range, 21-31 kg/m(2)). Agouti protein was correlated with FAS activity (r = 0.782, P: < 0.005). Similarly, human adipose tissue agouti mRNA level was also correlated with FAS mRNA level (r = 0.846, P: < 0.001). These data suggest that agouti may be another adipocyte-produced factor that modulates adipocyte lipid metabolism via a paracrine/autocrine mechanism.
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Affiliation(s)
- B Xue
- Department of Nutrition, University of Tennessee, Knoxville, TN 37996, USA
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10
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Wilson SM, Yip R, Swing DA, O'Sullivan TN, Zhang Y, Novak EK, Swank RT, Russell LB, Copeland NG, Jenkins NA. A mutation in Rab27a causes the vesicle transport defects observed in ashen mice. Proc Natl Acad Sci U S A 2000; 97:7933-8. [PMID: 10859366 PMCID: PMC16648 DOI: 10.1073/pnas.140212797] [Citation(s) in RCA: 336] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The dilute (d), leaden (ln), and ashen (ash) mutations provide a unique model system for studying vesicle transport in mammals. All three mutations produce a lightened coat color because of defects in pigment granule transport. In addition, all three mutations are suppressed by the semidominant dilute-suppressor (dsu), providing genetic evidence that these mutations function in the same or overlapping transport pathways. Previous studies showed that d encodes a major vesicle transport motor, myosin-VA, which is mutated in Griscelli syndrome patients. Here, using positional cloning and bacterial artificial chromosome rescue, we show that ash encodes Rab27a. Rab GTPases represent the largest branch of the p21 Ras superfamily and are recognized as key players in vesicular transport and organelle dynamics in eukaryotic cells. We also show that ash mice have platelet defects resulting in increased bleeding times and a reduction in the number of platelet dense granules. These defects have not been reported for d and ln mice. Collectively, our studies identify Rab27a as a critical gene for organelle-specific protein trafficking in melanocytes and platelets and suggest that Rab27a functions in both MyoVa dependent and independent pathways.
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Affiliation(s)
- S M Wilson
- Mouse Cancer Genetics Program, National Cancer Institute-Frederick Cancer Research and Development Center, Frederick, MD 21702, USA
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11
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Abstract
Dominant mutations at the mouse Agouti locus lead to ectopic expression of the Agouti gene and exhibit diabetes, obesity, and yellow coat color. Obese yellow mice are hyperinsulinemic and hyperleptinemic, and we hypothesized that Agouti directly induces leptin secretion. Accordingly, we used transgenic mice expressing agouti in adipocytes (under the control of aP2 promoter, aP212) to examine changes in leptin levels. Agouti expression in adipose tissue did not significantly alter food intake, weight gain, fat pad weight, or insulinemia; however, the transgenic mice were hyperglycemic. We demonstrated that plasma leptin levels are approximately twofold higher in aP212 transgenic mice compared with their respective controls, whereas ubiquitous expression of agouti (under the control of beta-actin promoter, BAP20) led to a sixfold increase in leptin. Insulin treatment of aP212 mice increased adipocyte leptin content without affecting plasma leptin levels. These findings were further confirmed in vitro in 3T3-L1 adipocytes treated with recombinant Agouti protein and/or insulin. Agouti but not insulin significantly increased leptin secretion, indicating that insulin enhances leptin synthesis but not secretion while Agouti increases both leptin synthesis and secretion. This increased leptin synthesis and secretion was due to increased leptin mRNA levels by Agouti. Interestingly, agouti regulation of leptin was not mediated by melanocortin receptor 4, previously implicated in agouti regulation of food intake. These results suggest that increased leptin secretion by agouti may serve to limit agouti-induced obesity, independent of melanocortin receptor antagonism, and indicate that interaction between obesity genes may play a key role in obesity.
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MESH Headings
- Adipocytes/cytology
- Adipocytes/drug effects
- Adipocytes/metabolism
- Adipose Tissue/chemistry
- Adipose Tissue/cytology
- Adipose Tissue/drug effects
- Agouti Signaling Protein
- Animals
- Carrier Proteins
- Cells, Cultured
- DNA-Binding Proteins
- Diabetes Mellitus/genetics
- Drug Administration Schedule
- Fatty Acid-Binding Protein 7
- Fatty Acid-Binding Proteins
- Homozygote
- Injections, Subcutaneous
- Insulin/administration & dosage
- Intercellular Signaling Peptides and Proteins
- Leptin/analysis
- Leptin/blood
- Leptin/genetics
- Male
- Melanocyte-Stimulating Hormones/pharmacology
- Mice
- Mice, Transgenic
- Neoplasm Proteins
- Nerve Tissue Proteins
- Obesity
- Promoter Regions, Genetic/genetics
- Proteins/genetics
- Proteins/metabolism
- Proteins/pharmacology
- RNA, Messenger/metabolism
- Receptor, Melanocortin, Type 4
- Receptors, Corticotropin/agonists
- Receptors, Leptin
- Receptors, Melanocortin
- Receptors, Peptide/antagonists & inhibitors
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Affiliation(s)
- K J Claycombe
- Department of Nutrition, University of Tennessee, Knoxville, Tennessee 37996, USA
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12
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Rees JL, Birch-Machin M, Flanagan N, Healy E, Phillips S, Todd C. Genetic studies of the human melanocortin-1 receptor. Ann N Y Acad Sci 1999; 885:134-42. [PMID: 10816646 DOI: 10.1111/j.1749-6632.1999.tb08670.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Genetic approaches have suggested a critical role for the melanocortin-1 receptor in the control of pigmentation. We showed that this gene is unusually polymorphic in European populations and that, of the many variants, three in particular appear to be associated with red hair or fair skin. Family studies suggest these are inherited as an autosomal recessive trait (or at least approximate to this in many families). To date all individuals with two of these three changes (homozygote or compound heterozygote) have red hair. Early functional studies are in keeping with defective signalling through MC1R. An interested and perhaps unexpected question relates to the evolutionary factors that have given rise to such variants. Two models can be proposed, that are based on multiple alleles with minor changes in function or genetic hitch-hicking.
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Affiliation(s)
- J L Rees
- Department of Dermatology, Medical School, Newcastle-upon-Tyne, United Kingdom.
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13
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Xue BZ, Wilkison WO, Mynatt RL, Moustaid N, Goldman M, Zemel MB. The agouti gene product stimulates pancreatic [beta]-cell Ca2+ signaling and insulin release. Physiol Genomics 1999; 1:11-9. [PMID: 11015556 DOI: 10.1152/physiolgenomics.1999.1.1.11] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Ubiquitous expression of the mouse agouti gene results in obesity and hyperinsulinemia. Human agouti is expressed in adipose tissue, and we found recombinant agouti protein to stimulate lipogenesis in adipocytes in a Ca(2+)-dependent fashion. However, adipocyte-specific agouti transgenic mice only became obese in the presence of hyperinsulinemia. Because intracellular Ca(2+) concentration ([Ca(2+)](i)) is a primary signal for insulin release, and we have shown agouti protein to increase [Ca(2+)](i) in several cell types, we examined the effects of agouti on [Ca(2+)](i) and insulin release. We demonstrated the expression of agouti in human pancreas and generated recombinant agouti to study its effects on Ca(2+) signaling and insulin release. Agouti (100 nM) stimulated Ca(2+) influx, [Ca(2+)](i) increase, and a marked stimulation of insulin release in two beta-cell lines (RIN-5F and HIT-T15; P < 0. 05). Agouti exerted comparable effects in isolated human pancreatic islets and beta-cells, with a 5-fold increase in Ca(2+) influx (P < 0.001) and a 2.2-fold increase in insulin release (P < 0.01). These data suggest a potential role for agouti in the development of hyperinsulinemia in humans.
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Affiliation(s)
- B Z Xue
- Department of Nutrition, University of Tennessee, Knoxville, Tennessee 37996, USA
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14
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Affiliation(s)
- A K Groves
- Division of Biology, California Institute of Technology, Pasadena 91125, USA
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15
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Xue B, Moustaid‐Moussa N, Wilkison WO, Zemel MB. The
agouti
gene product inhibits lipolysis in human adipocytes via a Ca
2+
‐dependent mechanism. FASEB J 1998. [DOI: 10.1096/fasebj.12.13.1391] [Citation(s) in RCA: 129] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Bingzhong Xue
- Department of Nutrition and MedicineThe University of Tennessee Knoxville Tennessee 37996 USA
- Zen‐Bio, Inc. Research Triangle Park North Carolina 27709 USA
| | - Naima Moustaid‐Moussa
- Department of Nutrition and MedicineThe University of Tennessee Knoxville Tennessee 37996 USA
- Zen‐Bio, Inc. Research Triangle Park North Carolina 27709 USA
| | - William O. Wilkison
- Department of Nutrition and MedicineThe University of Tennessee Knoxville Tennessee 37996 USA
- Zen‐Bio, Inc. Research Triangle Park North Carolina 27709 USA
| | - Michael B. Zemel
- Department of Nutrition and MedicineThe University of Tennessee Knoxville Tennessee 37996 USA
- Zen‐Bio, Inc. Research Triangle Park North Carolina 27709 USA
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16
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Aubin-Houzelstein G, Bernex F, Elbaz C, Panthier JJ. Survival of patchwork melanoblasts is dependent upon their number in the hair follicle at the end of embryogenesis. Dev Biol 1998. [DOI: 10.1016/s0012-1606(98)80004-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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17
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Kim JH, Kiefer LL, Woychik RP, Wilkison WO, Truesdale A, Ittoop O, Willard D, Nichols J, Zemel MB. Agouti regulation of intracellular calcium: role of melanocortin receptors. THE AMERICAN JOURNAL OF PHYSIOLOGY 1997; 272:E379-84. [PMID: 9124542 DOI: 10.1152/ajpendo.1997.272.3.e379] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Several dominant mutations at the murine agouti locus cause a syndrome of marked obesity and insulin resistance. We have recently reported that intracellular free Ca2+ concentration ([Ca2+]i) is elevated in viable yellow mice. Because [Ca2+]i has a key role in the pathogenesis of insulin resistance, obesity, and hypertension, the role of the purified agouti gene product in regulating [Ca2+]i was evaluated in a number of cell types. Purified murine agouti induced slow, sustained increases in [Ca2+]i in A7r5 vascular smooth muscle cells and 3T3-L1 adipocytes in a dose-dependent fashion. In L6 skeletal myocytes, agouti stimulated an increase in [Ca2+]i with an apparent concentration eliciting 50% of the maximal response (EC50) of 62 nM. This response was substantially inhibited by Ca2+ entry blockade with nitrendipine. To determine whether melanocortin receptors play a role in agouti regulation of [Ca2+]i, we examined the effect of melanocortin peptides and agouti in cells stably transfected with human melanocortin receptors. Human embryonic kidney cells (HEK-293 cells) transfected with either the human melanocortin 1 receptor (MC1R) or melanocortin 3 receptor responded to human agouti with slow, sustained increases in [Ca2+]i, whereas nontransfected HEK-293 cells with no melanocortin receptors did not respond to agouti. Dose-response curves in the MC1R line showed that agouti had an EC50 of 18 nM, which is comparable to that for agouti antagonism of (125)I-Nle,D-Phe-alpha-melanocyte-stimulating hormone binding in the same cell line. This direct effect of agouti on stimulating increases in [Ca2+]i suggests a potential mechanism for agouti-induced insulin resistance.
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Affiliation(s)
- J H Kim
- Department of Nutrition and Physiology Program, University of Tennessee, Knoxville 37996-1900, USA
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18
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Reid K, Turnley AM, Maxwell GD, Kurihara Y, Kurihara H, Bartlett PF, Murphy M. Multiple roles for endothelin in melanocyte development: regulation of progenitor number and stimulation of differentiation. Development 1996; 122:3911-9. [PMID: 9012511 DOI: 10.1242/dev.122.12.3911] [Citation(s) in RCA: 106] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Melanocytes in the skin are derived from the embryonic neural crest. Recently, mutations in endothelin 3 and the endothelin receptor B genes have been shown to result in gross pigment defects, indicating that this signalling pathway is required for melanocyte development. We have examined the effects of endothelins on melanocyte progenitors in cultures of mouse neural crest. Firstly, they stimulate an increase in progenitor number and act synergistically with another factor, Steel factor, in the survival and proliferation of the progenitors. These findings are consistent with findings from mice with natural mutations in the endothelin receptor B gene, which show an early loss of melanocyte progenitors. Secondly, endothelins induce differentiation of the progenitors into fully mature pigmented melanocytes. This finding is consistent with the expression of endothelins in the skin of mice at the initiation of pigmentation. The melanocytes generated in endothelin-treated cultures also become responsive to alpha melanocyte-stimulating hormone, which then acts to regulate the activity of the pigmentation pathway. These findings indicate two key roles for endothelin in melanocyte development: regulation of expansion of the progenitor pool and differentiation of progenitors into mature melanocytes.
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Affiliation(s)
- K Reid
- The Walter and Eliza Hall Institute of Medical Research, Royal Melbourne Hospital, Parkville, Victoria, Australia
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19
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Hosoda K, Hammer RE, Richardson JA, Baynash AG, Cheung JC, Giaid A, Yanagisawa M. Targeted and natural (piebald-lethal) mutations of endothelin-B receptor gene produce megacolon associated with spotted coat color in mice. Cell 1994; 79:1267-76. [PMID: 8001159 DOI: 10.1016/0092-8674(94)90017-5] [Citation(s) in RCA: 705] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Endothelins act on two subtypes of G protein-coupled receptors, termed endothelin-A and endothelin-B receptors. We report a targeted disruption of the mouse endothelin-B receptor (EDNRB) gene that results in aganglionic megacolon associated with coat color spotting, resembling a hereditary syndrome of mice, humans, and other mammalian species. Piebald-lethal (sl) mice exhibit a recessive phenotype identical to that of the EDNRB knockout mice. In crossbreeding studies, the two mutations show no complementation. Southern blotting revealed a deletion encompassing the entire EDNRB gene in the sl chromosome. A milder allele, piebald (s), which produces coat color spotting only, expresses low levels of structurally intact EDNRB mRNA and protein. These findings indicate an essential role for EDNRB in the development of two neural crest-derived cell lineages, myenteric ganglion neurons and epidermal melanocytes. We postulate that defects in the human EDNRB gene cause a hereditary form of Hirschsprung's disease that has recently been mapped to human chromosome 13, in which EDNRB is located.
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Affiliation(s)
- K Hosoda
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center at Dallas, Dallas 75235-9050
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20
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Johansson M, Ellegren H, Marklund L, Coppieters W, Andersson L. Linkage maps of porcine chromosomes 3, 6, and 9 based on 31 polymorphic markers. Mamm Genome 1994; 5:785-90. [PMID: 7894160 DOI: 10.1007/bf00292014] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Linkage maps of porcine Chromosomes (Chrs) 3, 6, and 9, based on 31 polymorphic markers, are reported. The markers include 14 microsatellites, 12 RFLPs, three protein polymorphisms, and two blood group loci. The genetic interpretations of 11 RFLPs are documented. The markers were scored in a three-generation Wild Boar/Large White pedigree, and genetic maps were constructed on the basis of two-point and multi-point linkage analysis. Altogether the maps span a genetic distance of 216 cM, and previous physical assignments indicate that the linkage groups cover major parts of the three chromosomes. Significant differences in recombination rates between the sexes were observed for all three chromosomes. The recombination rate on the q arm of Chr 6 was markedly low. Sixteen loci are informative with regard to comparative mapping, that is, they have previously been mapped in the human and/or mouse genomes.
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Affiliation(s)
- M Johansson
- Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala
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21
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Abstract
Dark-eyed albino (C44H) is a recessive allele at the mouse albino (c) locus, which encodes tyrosinase (monophenol,L-dopa:oxygen oxidoreductase, EC 1.14.18.1), the key enzyme in melanin synthesis. Similar to type IB oculocutaneous albinism in humans, overall production of pigment is greatly reduced in dark-eyed albino mice and obvious only in the eyes. We have studied the molecular basis of the c44H mutation and show that expression of the tyrosinase gene is not affected. After sequencing tyrosinase cDNA isolated from c44H/c44H homozygotes, we uncovered a single base alteration from wild type leading to a serine-to-isoleucine exchange. The importance of this mutation was demonstrated by generating transgenic mice containing a mutated tyrosinase minigene. This showed that the single base change was sufficient to severely depress pigment production in transgenic mice. We therefore conclude that the point mutation is responsible and sufficient to generate the dark-eyed albino phenotype.
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Affiliation(s)
- A Schmidt
- Swiss Institute for Experimental Cancer Research (ISREC), Epalinges
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22
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Abstract
Studies of mutagenesis in many organisms indicate that the majority (over 90%) of mutations are recessive to wild type. If recessiveness represents the 'default' state, what are the distinguishing features that make a minority of mutations give rise to dominant or semidominant characters? This review draws on the rapid expansion in knowledge of molecular and cellular biology to classify the molecular mechanisms of dominant mutation. The categories discussed include (1) reduced gene dosage, expression, or protein activity (haploinsufficiency); (2) increased gene dosage; (3) ectopic or temporally altered mRNA expression; (4) increased or constitutive protein activity; (5) dominant negative effects; (6) altered structural proteins; (7) toxic protein alterations; and (8) new protein functions. This provides a framework for understanding the basis of dominant genetic phenomena in humans and other organisms.
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Affiliation(s)
- A O Wilkie
- Institute of Medical Genetics, University Hospital of Wales, Heath Park, Cardiff, UK
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Regulation of Pigmentation During Mammalian Development. ACTA ACUST UNITED AC 1994. [DOI: 10.1016/s1064-2722(08)60009-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Chowdhary BP, Johansson M, Gu F, Bräuner-Nielsen P, Tomkinson B, Andersson L, Gustavsson I. Assignment of the linkage group EAM-TYRP2-TPP2 to chromosome 11 in pigs by in situ hybridization mapping of the TPP2 gene. Chromosome Res 1993; 1:175-9. [PMID: 7908839 DOI: 10.1007/bf00710771] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Restriction fragment length polymorphisms are described for the genes coding for tripeptidyl peptidase II (TPP2) and tyrosinase related protein II (TYRP2) in pigs. A linkage group comprising these loci and the locus for blood group M (EAM) was established by two-point lod score analysis in a three-generation pedigree. Multipoint analysis indicated the linear order EAM-1.1-TYRP2-8.4-TPP2 (recombination distances are given as Kosambi cM). The linkage group was assigned to porcine chromosome 11--the first on this chromosome--through in situ hybridization mapping of the TPP2 gene. TPP2 is the first gene localized on this chromosome using in situ hybridization.
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Affiliation(s)
- B P Chowdhary
- Department of Animal Breeding and Genetics, Swedish Agricultural University, Uppsala
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Bennett DC. Genetics, development, and malignancy of melanocytes. INTERNATIONAL REVIEW OF CYTOLOGY 1993; 146:191-260. [PMID: 8360012 DOI: 10.1016/s0074-7696(08)60383-6] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- D C Bennett
- St George's Hospital Medical School, London, United Kingdom
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Abstract
Light is a dominant mutant allele of the mouse brown locus which results in hairs pigmented only at their tips. The phenotype is due to premature melanocyte death. We have sequenced the tyrosinase-related protein-1 cDNA encoded at this locus from Light mice and found that it contains a single base alteration from wild-type, causing an Arg to Cys change in the protein. To further elucidate the mutant phenotype, we studied the expression of melanocyte specific genes in the skin of Light mice. We have demonstrated premature melanocyte death, but only in pigmented mice, indicating that the cell death is mediated through the inherent cytotoxicity of pigment production.
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Affiliation(s)
- R Johnson
- MRC Human Genetics Unit, Western General Hospital, Edinburgh, UK
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