Overview

Also Known As:MSUD murine model

This strain is currently unavailable due to replenishing of cryopreserved stocks. Interested customers can register interest.

In these triple mutant mice the absence of keto acid dehydrogenase (BCKDH) activity and E2 protein in liver tissue due to the Dbt^tm1Geh knock-out mutation is rescued by the two transgenes, rendering this strain as a useful model for Maple Syrup Urine Disease (MSUD).

Donating Investigator

Gregg E Homanics, University of Pittsburgh

Genetic overview

Genetic Background	Generation

Tg(Cebpb-tTA)5Bjd

Allele Type
Transgenic (Transactivator)

Dbt^tm1Geh

Allele Type	Gene Symbol	Gene Name
Targeted (Null/Knockout)	Dbt	dihydrolipoamide branched chain transacylase E2

Tg(tetO-DBT)A1Geh

Allele Type
Transgenic (Inducible, Hypomorph, Inserted expressed sequence, Humanized sequence)

View Genetics

Research Applications

Research Tools
Metabolism Research

View All Research Applications

Details

Detailed Description

Mice homozygous for the Dbt (E2) targeted mutation and carrying both the LAP-tTA and TRE-E2 transgenes are viable and fertile. The E2-targeted mutation leads to absence of branched-chain keto acid dehydrogenase (BCKDH) activity and E2 protein in liver tissue, but this absence is rescued by the two transgenes: liver-directed expression of the modified human BCKDH E2 subunit from the complimentary "Tet-off" transgenes abrogates the severity of Maple Syrup Urine Disease (MSUD) phenotype observed in E2-deficient single mutant mice. Triple mutant mice are a model for intermediate MSUD (iMSUD); BCKDH activity is only 5-6% of that found in wildtype mice. This low level of BCKDH activity is sufficient to allow survival, but insufficient to normalize circulating branched chain amino acids levels. Because these mice have near normal amounts of E2 protein, but only 5-6% of normal BCKDH enzyme activity, it is probable that the c-myc tag at the carboxy-terminus of the human E2 transgene interferes with enzymatic activity. The donating investigator reports that addition of the tetracycline analog doxycycline does not affect MSUD phenotype rescue. These mutant mice may be useful in studying metabolic disease, biochemistry, and both the complete/classic and intermediate forms of Maple Syrup Urine Disease.

Development

The mutant allele of branched-chain keto acid dehydrogenase E2 subunit (Dbt gene) was created by Dr. Gregg Homanics (University of Pittsburgh) using a targeting vector designed to replace part of exon 4 and all of exon 5 with a PGKneo cassette. The construct was electroporated into (129X1/SvJ x 129S1/Sv)F1-derived R1 embryonic stem (ES) cells. Correctly targeted ES cells were microinjected into C57BL/6J blastocysts. Chimeric mice were bred to C57BL/6J to generate heterozygous mice. Heterozygotes were then bred to LAP-tTA transgenic mice on a mixed (NMRI outbred;FVB;C57BL/6J) background. These mice were created by Dr. Hermann Bujard (Universitat Heidelberg) to express tetracycline-controlled transactivator (tTA) under control of the rat liver-enriched activator protein promoter. The TRE-E2 (or tetO-DBT*) transgene, also created by Dr. Gregg Homanics, contains a tetracycline response element and minimal human CMV promoter controlling a human E2 subunit (DBT gene) cDNA which has been modified to contain a 4x alanine linker followed by a c-myc epitope tag at the carboxy terminus. After injection of the transgene into C57BL/6J embryos, founder line A mice were bred with E2-deficient, LAP-tTA double mutant mice to generate this triple mutant strain.

Expression Data

Expressed Gene	tTA, tetracycline-controlled transactivator, E. coli
Site of Expression	Expresses tTA at high levels in the liver; see Stock No. 003563
Site of Expression	The targeted mutation leads to absence of branched-chain keto acid dehydrogenase activity and E2 protein in liver tissue.
Expressed Gene	DBT, dihydrolipoamide branched chain transacylase E2, human
Expressed Gene	tTA, tetracycline-controlled transactivator, E. coli
Site of Expression	Expresses tTA at high levels in the liver; see Stock No. 003563

Control Suggestions

Wild-type from the colony

Additional Information

Considerations for Choosing Controls

Selected References

Homanics GE; Skvorak K; Ferguson C; Watkins S; Paul HS. 2006. Production and characterization of murine models of classic and intermediate maple syrup urine disease. BMC Med Genet 7:33PubMed: 16579849 MGI: J:119973

View All References

Genetics

Tg(Cebpb-tTA)5Bjd

Allele Symbol: Tg(Cebpb-tTA)5Bjd

Allele Name	transgene insertion 5, Hermann Bujard
Allele Type	Transgenic (Transactivator)
Allele Synonym(s)	g(tTALap)5Bjd; LAP-tTA; Tg(tTALap)5Uh
Gene Symbol and Name	Tg(Cebpb-tTA)5Bjd, transgene insertion 5, Hermann Bujard
Gene Synonym(s)
Promoter	Cebpb, CCAAT/enhancer binding protein beta, rat
Expressed Gene	tTA, tetracycline-controlled transactivator, E. coli
Site of Expression	Expresses tTA at high levels in the liver; see Stock No. 003563
Strain of Origin	NMRI
Chromosome	UN
General Note	Transgenic mice on a C57BL/6J background are viable and fertile, and express tTA in the liver.
Molecular Note	This transgene contains the gene encoding the tetracycline regulated transactivator protein (tTA) driven by the rat Cebpb promoter (previously called liver-enriched activator protein).
Mutations Made By	Dr. Hermann Bujard, Universit¿t Heidelberg

Dbt^tm1Geh

Allele Symbol: Dbt^tm1Geh

Allele Name	targeted mutation 1, Gregg E Homanics
Allele Type	Targeted (Null/Knockout)
Allele Synonym(s)	E2 KO
Gene Symbol and Name	Dbt, dihydrolipoamide branched chain transacylase E2
Gene Synonym(s)
Site of Expression	The targeted mutation leads to absence of branched-chain keto acid dehydrogenase activity and E2 protein in liver tissue.
Strain of Origin	(129X1/SvJ x 129S1/Sv)F1-Kitl⁺
Chromosome	3
Molecular Note	A targeting vector was used to replace part of exon 4 and all of exon 5 with a PGKneo cassette.Southern blot and immunohistochemical analyses verify the absence of wild-type E2 transcripts and lack of E2 protein detection in homozygotes.

Tg(tetO-DBT)A1Geh

Allele Symbol: Tg(tetO-DBT)A1Geh

Allele Name	transgene insertion A1, Gregg E Homanics
Allele Type	Transgenic (Inducible, Hypomorph, Inserted expressed sequence, Humanized sequence)
Allele Synonym(s)	TRE-E2 (line A)
Gene Symbol and Name	Tg(tetO-DBT)A1Geh, transgene insertion A1, Gregg E Homanics
Gene Synonym(s)
Promoter	tetO, tet operator,
Expressed Gene	DBT, dihydrolipoamide branched chain transacylase E2, human
Expressed Gene	tTA, tetracycline-controlled transactivator, E. coli
Site of Expression	Expresses tTA at high levels in the liver; see Stock No. 003563
Strain of Origin	C57BL/6J
Chromosome	UN
Molecular Note	The TRE-E2 (or tetO-DBT) transgene contains a tetracycline response element and minimal human CMV promoter controlling a human E2 subunit (DBT gene) cDNA which has been modified to contain a 4x alanine linker followed by a c-myc epitope tag at the carboxy terminus to facilitate detection. Levels of the human E2 protein are approximately equal to mouse E2 protein in livers of control mice. However, when crossed to animals that express a transgene encoding the tetracycline regulated transactivator protein (Tg(tTALap)5Bjd) and are homozygous for a knockout allele of mouse E2 (Dbt^tm1Geh) are treated with doxycycline, the E2 protein levels correlate with only ~5-6% of normal branched-chain keto acid dehydrogenase (BCKDH) activity. It is one hypothesis that addition of the c-myc tag interferes with BCKDH subunit assembly (ie. interaction the human E2 subunit with mouse E1 and E3 complexes), thus reducing enzymatic activity.

Disease/Phenotype

Disease Terms

Characteristics of this human disease are associated with transgenes and other mutation types in the mouse.

maple syrup urine disease

Research Areas By Phenotype

This mouse can be used to support research in many areas including:

Research Tools
- Metabolism Research
- Cardiovascular Research
  - Tetop Tet System
- Tet Expression Systems
  - tTA/rtTA Expressing Strains
  - tTA/rtTA Responsive Strains
Metabolism Research
- Enzyme Deficiency

Mammalian Phenotype Terms by Genotype

The following phenotype relates to a compound genotype created using this strain

Genotype: Dbt^tm1Geh/Dbt^tm1Geh Tg(tetO-DBT)A1Geh/0 Tg(Cebpb-tTA)5Bjd/0
involves: 129S1/Sv * 129X1/SvJ * C57BL/6J * FVB * NMRI

homeostasis/metabolism phenotype

abnormal circulating amino acid level
- BCAA/alanine (BCAA -branched-chain amino acids - leucine + isoleucine + valine) values are intermediate between controls and Dbt-null mice between 4-7 weeks of age
- blood levels of alanine, glutamate, and glutamine are reduced compared to controls, but greater than in Dbt^tm1Geh homozygous mice

abnormal enzyme/coenzyme activity
- levels of branched-chain keto acid dehydrogenase (BCKDH) activity are only 5-6% of controls levels, despite nearly equal protein levels, indicating suboptimal BCKDH activity of protein assembled with human E2

mortality/aging

postnatal lethality
- approximately 4% of pups surviving to weaning have this genotype, compared to a theoretical survival rate or 14%, indicating partial rescue of the Dbt^tm1Geh phenotype

premature death
- transgenic mice survival is only ~16 weeks, when mice become moribund and are sacrificed

References

Homanics GE; Skvorak K; Ferguson C; Watkins S; Paul HS. 2006. Production and characterization of murine models of classic and intermediate maple syrup urine disease. BMC Med Genet 7:33PubMed: 16579849 MGI: J:119973

Additional - Dbt^tm1Geh related

Additional - Tg(Cebpb-tTA)5Bjd related

Additional - Tg(tetO-DBT)A1Geh related

Technical Support

CONTACT TECHNICAL SUPPORT

Genotyping Protocols
- Standard PCR:Generic rtTA-Alternate 1
- Standard PCR:Tg(Cebpb-tTA)5Bjd
- Probe:Generic tTA/rtTA
- QPCR:Tg(tTA)
- QPCR:Tg(tTA)
- QPCR:Tg(tTA) qPCR
- QPCR:Tg(tetO-DBT)A1Geh
- Standard PCR:Tg(tTA)
- Standard PCR:Dbt
- Standard PCR:Tg(tTA)
- Standard PCR:Tg(tetO-DBT)A1Geh
- Standard PCR:Generic tTA
- Probe:Generic rtTA-Alternate 1
- Genotyping resources and troubleshooting
Breeding Considerations

When maintaining a live colony, mice that are heterozygous for the targeted mutation and carriers of both transgenes can be bred together. Loss of one or both of the transgenes results in perinatal lethality (and Maple Syrup Urine Disease or MSUD phenotype) for mice homozygous for the targeted mutation.
- Additional Breeding and Husbandry Support
Citation
When using the MSUD murine model mouse strain in a publication, please cite the originating article(s) and include JAX stock #006999 in your Materials and Methods section.

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Licensing Information

Phone: 207-288-6470

Email: TechTran@jax.org

Also Known As:MSUD murine model

Donating Investigator

Genetic overview

Research Applications

Detailed Description

Development

Expression Data

Control Suggestions

Additional Information

Selected References

Tg(Cebpb-tTA)5Bjd

Allele Symbol: Tg(Cebpb-tTA)5Bjd

Dbttm1Geh

Allele Symbol: Dbttm1Geh

Tg(tetO-DBT)A1Geh

Allele Symbol: Tg(tetO-DBT)A1Geh

Disease Terms

Characteristics of this human disease are associated with transgenes and other mutation types in the mouse.

Research Areas By Phenotype

This mouse can be used to support research in many areas including:

Mammalian Phenotype Terms by Genotype

Genotype: Dbttm1Geh/Dbttm1Geh Tg(tetO-DBT)A1Geh/0 Tg(Cebpb-tTA)5Bjd/0involves: 129S1/Sv * 129X1/SvJ * C57BL/6J * FVB * NMRI

homeostasis/metabolism phenotype

mortality/aging

References

Additional - Dbttm1Geh related

Additional - Tg(Cebpb-tTA)5Bjd related

Additional - Tg(tetO-DBT)A1Geh related

Genotyping Protocols

Breeding Considerations

Citation

Strain Interest Registration

Contact Information

Interest

Terms Of Use

Additional Use Restrictions Apply

Licensing Information

Dbt^tm1Geh

Allele Symbol: Dbt^tm1Geh

Genotype: Dbt^tm1Geh/Dbt^tm1Geh Tg(tetO-DBT)A1Geh/0 Tg(Cebpb-tTA)5Bjd/0
involves: 129S1/Sv * 129X1/SvJ * C57BL/6J * FVB * NMRI

Additional - Dbt^tm1Geh related