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Transverse Aortic Constriction in Mice

Transverse Aortic Constriction in Mice

Published on: April 21, 2010

Mixed lineage kinase 3 requires a functional CRIB domain for regulation of blood pressure, cardiac hypertrophy, and

Pei-Wen Liu^1,2, Gregory L Martin¹, Weiyu Lin^1,2

¹Molecular Cardiology Research Institute, Tufts Medical Center, Boston, Massachusetts.

American Journal of Physiology. Heart and Circulatory Physiology

|July 22, 2022

Insights

The MLK3 CRIB domain is crucial for regulating blood pressure and cardiac function. Mutations disrupting this domain mimic MLK3 deletion, impacting cardiovascular homeostasis and pressure overload response.

Area of Science:

Cardiovascular Physiology
Molecular Mechanisms of Cardiovascular Disease
Signal Transduction in Cardiac Hypertrophy

Background:

Mixed lineage kinase 3 (MLK3) influences blood pressure and left ventricular function, but its precise mechanisms are not fully understood.
The Cdc42/Rac interactive binding (CRIB) domain is essential for MLK3 activation, yet its specific role in cardiovascular regulation remains to be elucidated.

Purpose of the Study:

To investigate the role of the MLK3 CRIB domain in cardiovascular physiology.
To determine the impact of MLK3 CRIB domain mutations on blood pressure, cardiac morphology, and response to pressure overload.

Main Methods:

Generation and analysis of MLK3 CRIB mutant (MLK3^C/C) mice with disrupted Cdc42/Rac binding.
Invasive hemodynamic measurements and echocardiography to assess blood pressure and cardiac function.
Analysis of MLK3 expression, JNK activation, and protein translocation in response to transaortic constriction (TAC).

Main Results:

MLK3^C/C mice exhibited elevated blood pressure and developed cardiac hypertrophy compared to wild-type littermates.
Reduced MLK3 mRNA and protein levels were observed in the left ventricles of MLK3^C/C mice.
In response to TAC, male MLK3^C/C mice showed impaired systolic function and reduced JNK activation, with absent MLK3 translocation to the membrane.

Conclusions:

The MLK3 CRIB domain is critical for regulating basal blood pressure and cardiac morphology.
MLK3 activation via its CRIB domain is essential for the compensatory left ventricular response to pressure overload.
Disruption of the MLK3 CRIB domain mimics the cardiovascular effects of MLK3 deletion, highlighting its importance in maintaining cardiovascular homeostasis.

Read full analysis

Abstract:

Mixed lineage kinase 3 (MLK3) modulates blood pressure and left ventricular function, but the mechanisms governing these effects remain unclear. In the current study, we therefore investigated the role of the MLK3 Cdc42/Rac interactive binding (CRIB) domain in cardiovascular physiology. We examined baseline and left ventricular pressure overload responses in a MLK3 CRIB mutant (MLK3^C/C) mouse, which harbors point mutations in the CRIB domain to disrupt MLK3 activation by Cdc42. Male and female MLK3^C/C mice displayed increased invasively measured blood pressure compared with wild-type (MLK3^+/+) littermate controls. MLK3^C/C mice of both sexes also developed left and right ventricular hypertrophy but normal baseline LV function by echocardiography and invasive hemodynamics. In LV tissue from MLK3^C/C mice, map3k11 mRNA, which encodes MLK3, and MLK3 protein were reduced by 74 ± 6% and 73 ± 7%, respectively. After 1-wk LV pressure overload with 25-gauge transaortic constriction (TAC), male MLK3^C/C mice developed no differences in LV hypertrophy but displayed reduction in the LV systolic indices ejection fraction and dP/dt normalized to instantaneous pressure. JNK activation was also reduced in LV tissue of MLK3^C/C TAC mice. TAC induced MLK3 translocation from cytosolic fraction to membrane fraction in LV tissue from MLK3^+/+ but not MLK3^C/C mice. These findings identify a role of the MLK3 CRIB domain in MLK3 regulation of basal blood pressure and cardiac morphology, and in promoting the compensatory LV response to pressure overload.NEW & NOTEWORTHY Here, we identified that the presence of two discrete point mutations within the Cdc42/Rac interaction and binding domain of the protein MLK3 recapitulates the effects of whole body MLK3 deletion on blood pressure, cardiac hypertrophy, and left ventricular compensation after pressure overload. These findings implicate the CRIB domain, and thus MLK3 activation by this domain, as critical for maintenance of cardiovascular homeostasis.

Keywords:

cardiac hypertrophy heart failure hypertension mixed lineage kinase molecular signaling

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