title: A novel transgenic mouse model of lysosomal storage disorder.
abstract: Knockout technology has proven useful for delineating functional roles of specific genes. Here we describe and provide an explanation for striking pathology that occurs in a subset of genetically engineered mice expressing a rat CaVβ2a transgene under control of the cardiac α-myosin heavy chain promoter. Lesions were limited to mice homozygous for transgene and independent of native Cacnb2 genomic copy number. Gross findings included an atrophied pancreas; decreased adipose tissue; thickened, orange intestines; and enlarged liver, spleen, and abdominal lymph nodes. Immune cell infiltration and cell engulfment by macrophages were associated with loss of pancreatic acinar cells. Foamy macrophages diffusely infiltrated the small intestine's lamina propria, while similar macrophage aggregates packed liver and splenic red pulp sinusoids. Periodic acid-Schiff-positive, diastase-resistant, iron-negative, Oil Red O-positive, and autofluorescent cytoplasm was indicative of a lipid storage disorder. Electron microscopic analysis revealed liver sinusoids distended by clusters of macrophages containing intracellular myelin "swirls" and hepatocytes with enlarged lysosomes. Additionally, build up of cholesterol, cholesterol esters, and triglycerides, along with changes in liver metabolic enzyme levels, were consistent with a lipid processing defect. Because of this complex pathology, we examined the transgene insertion site. Multiple transgene copies inserted into chromosome 19; at this same site, an approximate 180,000 base pair deletion occurred, ablating cholesterol 25-hydroxylase and partially deleting lysosomal acid lipase and CD95 Loss of gene function can account for the altered lipid processing, along with hypertrophy of the immune system, which define this phenotype, and serendipitously provides a novel mouse model of lysosomal storage disorder.
authors.affiliation: Cummings School of Veterinary Medicine, Tufts University, Grafton, Massachusetts.|Department of Microbiology & Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts.
authors.forename: Sonia
authors.initials: S
authors.lastname: Ortiz-Miranda
authors.affiliation: Departments of Biochemistry & Molecular Genetics and Ophthalmology & Visual Science, University of Louisville, Louisville, Kentucky.
authors.forename: Rui
authors.initials: R
authors.lastname: Ji
authors.affiliation: Diabetes Center of Excellence, University of Massachusetts Medical School, Worcester, Massachusetts.|Department of Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts.
authors.forename: Agata
authors.initials: A
authors.lastname: Jurczyk
authors.affiliation: Diabetes Center of Excellence, University of Massachusetts Medical School, Worcester, Massachusetts.
authors.forename: Ken-Edwin
authors.initials: KE
authors.lastname: Aryee
authors.affiliation: Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts.|Proteomics and Mass Spectrometry Facility, University of Massachusetts Medical School, Worcester, Massachusetts; and.
authors.forename: Shunyan
authors.initials: S
authors.lastname: Mo
authors.affiliation: Departments of Pharmacology & Toxicology and Pathology, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas.
authors.forename: Terry
authors.initials: T
authors.lastname: Fletcher
authors.affiliation: Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts.|Proteomics and Mass Spectrometry Facility, University of Massachusetts Medical School, Worcester, Massachusetts; and.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Shaffer
authors.affiliation: Diabetes Center of Excellence, University of Massachusetts Medical School, Worcester, Massachusetts.|Department of Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts.
authors.forename: Dale L
authors.initials: DL
authors.lastname: Greiner
authors.affiliation: Diabetes Center of Excellence, University of Massachusetts Medical School, Worcester, Massachusetts.|Department of Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts.
authors.forename: Rita
authors.initials: R
authors.lastname: Bortell
authors.affiliation: Departments of Biochemistry & Molecular Genetics and Ophthalmology & Visual Science, University of Louisville, Louisville, Kentucky.
authors.forename: Ronald G
authors.initials: RG
authors.lastname: Gregg
authors.affiliation: Departments of Biochemistry & Molecular Genetics and Ophthalmology & Visual Science, University of Louisville, Louisville, Kentucky.
authors.forename: Alan
authors.initials: A
authors.lastname: Cheng
authors.affiliation: Departments of Pharmacology & Toxicology and Pathology, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas.
authors.forename: Leah J
authors.initials: LJ
authors.lastname: Hennings
authors.affiliation: Department of Microbiology & Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts; ann.rittenhouse@umassmed.edu.
authors.forename: Ann R
authors.identifier: 0000-0002-7446-230X
authors.initials: AR
authors.lastname: Rittenhouse
mesh_terms: D000818:Animals; D020746:Calcium Channels, L-Type / Q000235:genetics*; D002784:Cholesterol / Q000378:metabolism*; D004195:Disease Models, Animal; D022781:Hepatocytes / Q000378:metabolism / Q000473:pathology; D008099:Liver / Q000378:metabolism / Q000473:pathology; D016464:Lysosomal Storage Diseases / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D008247:Lysosomes / Q000378:metabolism / Q000473:pathology; D008264:Macrophages / Q000378:metabolism / Q000473:pathology; D051379:Mice; D008822:Mice, Transgenic; D011401:Promoter Regions, Genetic; D013154:Spleen / Q000378:metabolism / Q000473:pathology; D014280:Triglycerides / Q000378:metabolism*
chemical_list: C491528:Cacnb2 protein, mouse; D020746:Calcium Channels, L-Type; D014280:Triglycerides; D002784:Cholesterol
keywords: CACNB2; TNF Receptor Superfamily Member 6; lincRNA; lysosomal storage disorders; miRNA