Intracellular Enhanced Cyan Fluorescent Protein/Angiotensin II Does Not Modify Angiotensinogen Accumulation in...

Area of Science:

• Molecular Biology
• Cardiovascular Physiology
• Genetics

Background:

• Extracellular angiotensin is known to upregulate renin and angiotensinogen (AGT).
• Enhanced cyan fluorescent protein/angiotensin II (ECFP/AngII) transgenic mice exhibit hypertension and kidney thrombotic microangiopathy.
• The role of intracellular angiotensin II in regulating AGT expression requires further investigation.

Purpose of the Study:

• To evaluate the effect of intracellular angiotensin II (AngII) on angiotensinogen (AGT) messenger RNA (mRNA) and protein levels.
• To determine if ECFP/AngII transgene expression influences endogenous AGT synthesis in transgenic mice.

Main Methods:

• Extraction of total mRNA using the guanidinium thiocyanate method.
• Protein extraction via tissue homogenization.
• Analysis of AGT mRNA levels using Northern blot with an 18S ribosomal RNA control.
• Quantification of AGT protein levels through immunoblotting with actin and tubulin controls.

Main Results:

• Liver AGT mRNA levels were significantly higher (12-fold) than in the brain or kidney, but showed no difference between wild-type (WT) and homozygous (HO) transgenic mice.
• Liver AGT protein levels were 3.2-fold greater than in the brain or kidney, with no observed differences between WT and HO transgenic mice.
• No quantifiable differences in AGT mRNA or protein were found between ECFP/AngII transgenic and WT mice in major organs.

Conclusions:

• ECFP/AngII transgene expression does not alter AGT mRNA or protein levels in the kidney, liver, or brain of transgenic mice.
• The observed hypertension and kidney thrombosis in ECFP/AngII mice are not caused by increased intracellular AGT synthesis.
• Findings align with previous studies showing no increase in circulating AngII, suggesting alternative mechanisms for the observed phenotype.