Redox signaling and splicing dependent change in myosin phosphatase underlie early versus late changes in NO vasodilator reserve in a mouse LPS model of sepsis.
Microcirculatory dysfunction may cause tissue malperfusion and progression to organ failure in the later stages of sepsis, but the role of smooth muscle contractile dysfunction is uncertain. Mice were given intraperitoneal LPS, and mesenteric arteries were harvested at 6-h intervals for analyses of gene expression and contractile function by wire myography. Contractile (myosin and actin) and regulatory [myosin light chain kinase and phosphatase subunits (Mypt1, CPI-17)] mRNAs and proteins were decreased in mesenteric arteries at 24 h concordant with reduced force generation to depolarization, Ca(2+), and phenylephrine. Vasodilator sensitivity to DEA/nitric oxide (NO) and cGMP under Ca(2+) clamp were increased at 24 h after LPS concordant with a switch to Mypt1 exon 24- splice variant coding for a leucine zipper (LZ) motif required for PKG-1α activation of myosin phosphatase. This was reproduced by smooth muscle-specific deletion of Mypt1 exon 24, causing a shift to the Mypt1 LZ+ isoform. These mice had significantly lower resting blood pressure than control mice but similar hypotensive responses to LPS. The vasodilator sensitivity of wild-type mice to DEA/NO, but not cGMP, was increased at 6 h after LPS. This was abrogated in mice with a redox dead version of PKG-1α (Cys42Ser). Enhanced vasorelaxation in early endotoxemia is mediated by redox signaling through PKG-1α but in later endotoxemia by myosin phosphatase isoform shifts enhancing sensitivity to NO/cGMP as well as smooth muscle atrophy. Muscle atrophy and modulation may be a novel target to suppress microcirculatory dysfunction; however, inactivation of inducible NO synthase, treatment with the IL-1 antagonist IL-1ra, or early activation of α-adrenergic signaling did not suppressed this response.
Department of Medicine, Divisions of Cardiovascular Medicine and Nephrology, University of Maryland, Baltimore, Maryland.
John J
JJ
Reho
Department of Medicine, Divisions of Cardiovascular Medicine and Nephrology, University of Maryland, Baltimore, Maryland.
Xiaoxu
X
Zheng
Department of Medicine, Divisions of Cardiovascular Medicine and Nephrology, University of Maryland, Baltimore, Maryland.
Laureano D
LD
Asico
Department of Medicine, Divisions of Cardiovascular Medicine and Nephrology, University of Maryland, Baltimore, Maryland sfisher1@medicine.umaryland.edu.
Steven A
SA
Fisher
D000818:Animals; D006152:Cyclic GMP / Q000378:metabolism; D062965:Cyclic GMP-Dependent Protein Kinase Type I / Q000172:deficiency / Q000235:genetics; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation; D005838:Genotype; D047908:Intracellular Signaling Peptides and Proteins; D007527:Isoenzymes; D008070:Lipopolysaccharides; D008297:Male; D008638:Mesenteric Arteries / Q000201:enzymology / Q000503:physiopathology; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008833:Microcirculation; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000201:enzymology* / Q000503:physiopathology; D009133:Muscular Atrophy / Q000139:chemically induced / Q000201:enzymology / Q000503:physiopathology; D009219:Myosin-Light-Chain Kinase / Q000172:deficiency / Q000235:genetics; D043263:Myosin-Light-Chain Phosphatase / Q000235:genetics / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000172:deficiency / Q000235:genetics; D010084:Oxidation-Reduction; D010641:Phenotype; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D018805:Sepsis / Q000139:chemically induced / Q000201:enzymology* / Q000235:genetics / Q000503:physiopathology; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology
D047908:Intracellular Signaling Peptides and Proteins; D007527:Isoenzymes; D008070:Lipopolysaccharides; D009124:Muscle Proteins; D010750:Phosphoproteins; C491520:Ppp1r14a protein, mouse; D012333:RNA, Messenger; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; C440499:lipopolysaccharide, Escherichia coli O111 B4; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D062965:Cyclic GMP-Dependent Protein Kinase Type I; D009219:Myosin-Light-Chain Kinase; D043263:Myosin-Light-Chain Phosphatase; C510645:Ppp1r12a protein, mouse; D006152:Cyclic GMP
endotoxemia; mesenteric artery; myosin phosphatase