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Phenotypes Associated with This Genotype
Genotype
MGI:4943706
Allelic
Composition
Ltbp4Gt(U3Cre)1Vmel/Ltbp4Gt(U3Cre)1Vmel
Genetic
Background
B6.129S2-Ltbp4Gt(U3Cre)1Vmel
Find Mice Using the International Mouse Strain Resource (IMSR)
Mouse lines carrying:
Ltbp4Gt(U3Cre)1Vmel mutation (1 available); any Ltbp4 mutation (120 available)
phenotype observed in females
phenotype observed in males
N normal phenotype
respiratory system
• by 6-8 months of age, mutant lungs exceeded normal size by 3-fold
• by 6-8 months, alveolar spaces are significantly reduced in number
• by 6-8 months, alveoli are surrounded by thin, dysplastic, and frequently incomplete septal walls
• at 24-32 wks of age, the lobular connective tissue is reduced and replaced by multifocal atelectatic areas
• by 6-8 months, alveolar spaces are enlarged and inflated
• a mild emphysema-like condition is already evident at birth and progresses with increasing age
• a moderate emphysema associated with rupture of septal walls is observed at 12-14 wks
• severe emphysema with extensive atelectatic areas is noted by 24-32 wks
• at 12 wks of age, mutant lungs lack normal elastic fibers and display multiple patches of fragmented and condensed elastin, unlike wild-type lungs
• by 6-8 months, most mice develop severe dyspnea and need to be sacrificed
• mice remain clinically healthy up to 6 months of age but their health deteriorates therefater
• an almost complete loss of pulmonary elasticity is observed at 24-32 wks of age

digestive/alimentary system
• extensive edema in the mucosal layer of the colorectal region at 4 wks of age
• at 12-14 weeks of age, intestinal goblet cell numbers are increased
• colorectal adenocarcinomas are formed by enlarged and dysplastic crypts lined by neoplastic epithelial cells
• crypts display various degrees of epithelial cell detachment and infiltrate all layers of the colorectal wall
• superficial rectal ulcerations noted at 4 months of age
• by 4 wks of age, solitary ulcers associated with epithelial hyperplasia and occasional crypts infiltrating the submucosal layer of the colonic wall are observed
• at 12 wks of age, mutant colons lack normal elastic fibers and display multiple patches of fragmented and condensed elastin, unlike wild-type colons
• by 4 wks of age, mice develop a rectal prolapse induced by extensive edema in the mucosal layer of the colorectal region
• at 12-14 wks of age, most animals develop adenomas consisting of enlarged and abnormally branched cystic glands with increased numbers of goblet cells
• by 6-8 months, all mice show invasive colorectal carcinomas in the distal portion of the colorectum with diameters of 0.7-1.5 cm
• at autopsy, massive inflammatory infiltrations of the colonic wall associated with a reactive splenomegaly are observed
• by 6-8 months, most mice exhibit rectal prolapse infections that frequently progress to ulcerative proctitis

cardiovascular system
• ubiquitous myofibrillar hypertrophy is observed at 24-32 wks of age
• by 6-8 months, the cardiac/body weight index exceeds normal values by 30%
• cardiomyopathy progresses from initial right ventricular dilatation (12-14 wks) to biventricular dilatation (24-32 wks)
• at 12-14 wks of age, a moderate cardiomyopathy associated with right ventricular dilatation is observed; not seen at 4-6 wks of age
• by 24-32 wks of age, biventricular dilatation is observed
• however, elastic fibers in the heart appear normal, suggesting that the cardiomyopathy is mostly secondary to emphysema

neoplasm
• at 12-14 wks of age, most animals develop adenomas consisting of enlarged and abnormally branched cystic glands with increased numbers of goblet cells
• by 6-8 months, all mice show invasive colorectal carcinomas in the distal portion of the colorectum with diameters of 0.7-1.5 cm

immune system
• at autopsy, massive inflammatory infiltrations of the colonic wall associated with a reactive splenomegaly are observed
• by 6-8 months, most mice exhibit rectal prolapse infections that frequently progress to ulcerative proctitis
• reactive splenomegaly is observed upon autopsy at 6-8 months of age

muscle
• ubiquitous myofibrillar hypertrophy is observed at 24-32 wks of age
• at 12-14 wks of age, a moderate cardiomyopathy associated with right ventricular dilatation is observed; not seen at 4-6 wks of age
• by 24-32 wks of age, biventricular dilatation is observed
• however, elastic fibers in the heart appear normal, suggesting that the cardiomyopathy is mostly secondary to emphysema

endocrine/exocrine glands
• colorectal adenocarcinomas are formed by enlarged and dysplastic crypts lined by neoplastic epithelial cells
• crypts display various degrees of epithelial cell detachment and infiltrate all layers of the colorectal wall

hematopoietic system
• reactive splenomegaly is observed upon autopsy at 6-8 months of age

cellular
• at 12-14 weeks of age, intestinal goblet cell numbers are increased
• impaired export and/or deposition of small latent Tgfb1 in the extracellular matrix, resulting in the absence of extracellular Tgfb1 in affected tissues (lung, colon, and heart) but not in kidney
• as a result, epithelial cells show reduced levels of phosphorylated Smad2 proteins, overexpress Myc, and undergo uncontrolled proliferation

growth/size/body
• by 6-8 months, the cardiac/body weight index exceeds normal values by 30%
• by 6-8 months of age, mutant lungs exceeded normal size by 3-fold
• reactive splenomegaly is observed upon autopsy at 6-8 months of age


Contributing Projects:
Mouse Genome Database (MGD), Gene Expression Database (GXD), Mouse Models of Human Cancer database (MMHCdb) (formerly Mouse Tumor Biology (MTB)), Gene Ontology (GO)
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last database update
04/30/2024
MGI 6.23
The Jackson Laboratory