B6.Cg-Tg(Myh6-Tnni3*S23A*S24D*S43D*S45D)354Ammu/Mmjax

Stock number: 032409
Product name: TnI PKA/PKC
Research areas: Cardiovascular Research

Description

PKA-TnI transgenic mice express a rat troponin I, cardiac 3 (Tnni3 or TnI) gene modified to include the following substitutions S23A, S24D, S43D, S45D altering phosphorylation by protein kinase A and C. Transgenic mice exhibit cardiac dysfunction under stress. This strain may be useful in studies of heart failure and PKA/PKC-mediated phosphorylation.

Detailed description

The PKA-TnI transgene expresses a rat troponin I, cardiac 3 (Tnni3 or TnI) cDNA sequence modified to substitute alanine or aspartic acid for serine in the following residues: S23A, S24D, S43D, S45D (reported as S22A, S23D, S42D, S44D based on the mature peptide sequence). Altering the protein kinase A (PKA) targeted residues 23 and 24 mimics the effects of constitutive phosphorylation. Altering the protein kinase C (PKC) targeted residues 43 and 45 mimics the effects of partial dephosphorylation. Tnni3 encodes the inhibitory subunit of the troponin complex located in the thin filaments of striated muscle. Phosphorylation of TNNI3 modulates myofilament function and alters cardiac muscle shortening and relaxation kinetics and the steady state relationship of calcium and myofilament tension. Mice hemizygous for the PKA-TnI transgene are viable and fertile. Echocardiography on PKA-TnI mice indicates reduced fractional shortening and slight left ventricle chamber dilation as compared to non-transgenic mice. In most respects, this strain appears normal, however, under stress underlying cardiac dysfunction is revealed. In vivo cardiac pressure-volume studies results in an exaggerated rise in relaxation time constant for a given increase in afterload. Increasing heart rate from 400 to 700 beats/min elevates contractility to a lesser degree in PKA-TnI hearts than in hearts from non-transgenic mice. This strain may be useful in studies of heart failure and PKA/PKC-mediated phosphorylation.

This strain is one of a set of modified TnI transgenes including: B6.Cg-Tg(Myh6-Tnni3*S23D*S24D)69Ammu/Mmjax - Stock No. 050529.

Development

The TnI PKA/PKC transgene was designed with the mouse α-myosin heavy chain (α-MHC or Myh6) promoter directing expression of a modified rat troponin I, cardiac 3 (Tnni3 or TnI) cDNA sequence. The Tnni3 sequence contains a serine to alanine substitution at residue 23 (S23A, reported as 22, which is based on the mature peptide sequence), a serine to aspartic acid substitution at residue 24 (S24D, reported as 23) and serine to aspartic acid substitutions at residues 43 and 45 (S43D, S45D, reported as 42 and 44). The construct was microinjected into (C57BL/6 x SJL/J) fertilized oocytes. Founder mouse 354 was subsequently established. The strain has been crossed to C57BL/6J mice for at least 10 generations. Upon arrival, TnI PKA/PKC mice were bred to C57BL/6J inbred mice for at least one generation to establish the colony.

Allele

Symbol: Tg(Myh6-Tnni3*S23A*S24D*S43D*S45D)354Ammu
Name: transgene insertion 354, Anne Murphy
MGI accession ID: MGI:6201702
Generation method: Transgenic
Attributes: Inserted expressed sequence
Synonyms: TnI PKA/PKC
Marker symbol: Tg(Myh6-Tnni3*S23A*S24D*S43D*S45D)354Ammu
Marker name: transgene insertion 354, Anne Murphy
Chromosome: UN
Strain of origin: C57BL/6 x SJL
Site of expression: cardiac myocytes

Molecular note: The transgene was designed with the mouse alpha-myosin heavy chain (Myh6) promoter directing expression of a modified rat troponin I, cardiac 3 (Tnni3) cDNA. The Tnni3 sequence encodes a protein containing a serine to alanine substitution at residue 23 (S23A), a serine to aspartic acid substitution at residue 24 (S24D) and serine to aspartic acid substitutions at residues 43 and 45 (S43D, S45D) (mRNA RefSeq: NM_017144.2; protein RefSeq: NP_058840.1). (These amino acid positions differ by one from those reported, which were based on the mature peptide sequence lacking the initiating methionine.) Founder line 354 was selected as the representative line.