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Age‐associated Arterial Dysfunction is Rejuvenated by Targeted Reactivation of Protein Kinase Cδ
Author(s) -
Cho Jae Min,
Park Seul-Ki,
La Salle D Taylor,
Cerbie James,
Bledsoe Amber,
Nelson Ashley,
Morgan David E.,
Richardson Russell S.,
Shiu Yan-Ting,
Boudina Sihem,
Trinity Joel D.,
Symons J. David
Publication year - 2020
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2020.34.s1.02731
Subject(s) - autophagy , enos , protein kinase c , medicine , endocrinology , biology , nitric oxide , microbiology and biotechnology , apoptosis , kinase , nitric oxide synthase , biochemistry
Genetic repression of endothelial cell (EC) autophagy impairs EC glycolysis and EC ATP production (Bharath et al., ATVB, 2017) . This limits purinergic 2Y1 receptor mediated activating phosphorylation of EC nitric oxide (NO) synthase (p‐eNOS S1177 ) via protein kinase C δ (PKCδ T505 ). A consequence of this impaired signaling pathway is compromised shear‐stress ‐ induced NO generation. We sought to determine whether reactivating PKCδ T505 in the context of repressed EC autophagy restores EC function. First, we hypothesized that bryostatin‐1 (Bry‐1) rescues shear‐induced p‐eNOS S1177 and NO generation in human arterial ECs (HAECs) with genetic autophagy compromise. Bry‐1 binds to the regulatory C1 domain of the PKC isoforms. As anticipated, laminar shear stress x 45‐min elevated (p<0.05) p‐PKCδ T505 , p‐eNOS S1177 , and NO generation in HAECs with intact autophagy but not in HAECs after Atg3 knockout (+Atg3KO; n=6). All responses were restored in HAECs + Atg3KO by incubation with Bry‐1, without affecting autophagy, cell death, or apoptosis. Next, we hypothesized that reactivating PKCδ restores vasodilatory function in arteries from aged mice with physiological repression of vascular autophagy. Lower (p<0.05) mRNA and protein expression of autophagy indexes was confirmed in primary arterial ECs and vascular homogenates from ~24 month (old; O) vs. ~7 month (adult, A) old male mice (n=5). Further, basal, glucose‐stimulated, and oligomycin‐stimulated extracellular acidification rate was suppressed (p<0.05) in primary arterial ECs from O vs. A mice, indicating impaired EC glycolysis. Femoral arteries from the same mice were examined ex vivo. Vasodilatory responses to intraluminal flow evoked by pressure gradients of 6, 12, 18, 24, and 30 mmHg (x 3‐min each @ 60 mmHg) was blunted (p<0.05) in O vs. A mice (n=5). As hypothesized, Bry‐1 restored intraluminal flow‐mediated vasodilation (FMD) in arteries from O mice to values observed in A mice (n=5). Vascular smooth muscle function, evaluated by vasodilatory responses to sodium nitroprusside, was not different between groups. In a separate cohort of vessels, nitric oxide synthase inhibition attenuated intraluminal FMD to a greater extent (p<0.05) in arteries from A vs. O mice (n=4). Finally, we hypothesized that Bry‐1 improves PKCδ T505 and p‐eNOS S1177 in primary arterial ECs from aged humans. As background, earlier we reported p‐PKCδ T505 and p‐eNOS S1177 was lower (p<0.05) in primary ECs obtained from the radial artery of older (~ 68 y) vs. adult (~ 23 y) males that also displayed impaired brachial artery FMD peak (Park et al, FASEB J, 2019) . To test this, radial artery ECs were obtained from older males (n=4) via sterile j‐wire. Treatment of non‐fixed ECs with Bry‐1 elevated (p<0.05) PKCδ T505 and p‐eNOS S1177 vs. non‐fixed ECs treated with vehicle. Here, we provide proof of concept that activating p‐PKCδ T505 using Bry‐1 in the context of impaired vascular autophagy has potential to rejuvenate EC function. Support or Funding Information JMC (UU Graduate Research Fellowship); SKP (17POST33670663); JDS (NIH RO1HL141540)