21 research outputs found
Cell-Type Specific Expression of a Dominant Negative PKA Mutation in Mice
We employed the Cre recombinase/loxP system to create a mouse line in which PKA activity can be inhibited in any cell-type that expresses Cre recombinase. The mouse line carries a mutant Prkar1a allele encoding a glycine to aspartate substitution at position 324 in the carboxy-terminal cAMP-binding domain (site B). This mutation produces a dominant negative RIα regulatory subunit (RIαB) and leads to inhibition of PKA activity. Insertion of a loxP-flanked neomycin cassette in the intron preceding the site B mutation prevents expression of the mutant RIαB allele until Cre-mediated excision of the cassette occurs. Embryonic stem cells expressing RIαB demonstrated a reduction in PKA activity and inhibition of cAMP-responsive gene expression. Mice expressing RIαB in hepatocytes exhibited reduced PKA activity, normal fasting induced gene expression, and enhanced glucose disposal. Activation of the RIαB allele in vivo provides a novel system for the analysis of PKA function in physiology
The amounts of rat liver cyclic AMP-dependent protein kinase I and II are differentially regulated by diet
Spectroscopic Characterization of the 3+ and 2+ Oxidation States of Europium in a Macrocyclic Tetraglycinate Complex
Spectroscopic Characterization of the 3+ and 2+ Oxidation States of Europium in a Macrocyclic Tetraglycinate Complex
The
3+ and 2+ oxidation states of europium have drastically different
magnetic and spectroscopic properties. Electrochemical measurements
are often used to probe Eu<sup>III/II</sup> oxidation state changes,
but a full suite of spectroscopic characterization is necessary to
demonstrate conversion between these two oxidation states in solution.
Here, we report the facile conversion of an europiumÂ(III) tetraglycinate
complex into its Eu<sup>II</sup> analogue. We present electrochemical,
luminescence, electron paramagnetic resonance, UV–visible,
and NMR spectroscopic data demonstrating complete reversibility from
the reduction and oxidation of the 3+ and 2+ oxidation states, respectively.
The Eu<sup>II</sup>-containing analogue has kinetic stability within
the range of clinically approved Gd<sup>III</sup>-containing complexes
using an acid-catalyzed dissociation experiment. Additionally, we
demonstrate that the 3+ and 2+ oxidation states provide redox-responsive
behavior through chemical-exchange saturation transfer or proton relaxation,
respectively. These results will be applicable to a wide range of
redox-responsive contrast agents and Eu-containing complexes