Akt1/PKB upregulation leads to vascular smooth muscle cell hypertrophy and polyploidization
Mary L. Hixon, … , Kenneth Walsh, Antonio Gualberto
Mary L. Hixon, … , Kenneth Walsh, Antonio Gualberto
Published October 15, 2000
Citation Information: J Clin Invest. 2000;106(8):1011-1020. https://doi.org/10.1172/JCI8252.
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Article

Akt1/PKB upregulation leads to vascular smooth muscle cell hypertrophy and polyploidization

Abstract

Vascular smooth muscle cells (VSMCs) at capacitance arteries of hypertensive individuals and animals undergo marked age- and blood pressure–dependent polyploidization and hypertrophy. We show here that VSMCs at capacitance arteries of rat models of hypertension display high levels of Akt1/PKB protein and activity. Gene transfer of Akt1 to VSMCs isolated from a normotensive rat strain was sufficient to abrogate the activity of the mitotic spindle cell–cycle checkpoint, promoting polyploidization and hypertrophy. Furthermore, the hypertrophic agent angiotensin II induced VSMC polyploidization in an Akt1-dependent manner. These results demonstrate that Akt1 regulates ploidy levels in VSMCs and contributes to vascular smooth muscle polyploidization and hypertrophy during hypertension.

Authors

Mary L. Hixon, Carlos Muro-Cacho, Mark W. Wagner, Carlos Obejero-Paz, Elise Millie, Yasushi Fujio, Yasuko Kureishi, Terry Hassold, Kenneth Walsh, Antonio Gualberto

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Figure 4

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Akt1-transduced VSMCs fail to arrest growth at mitosis. (a) Cell-cycle a...
Akt1-transduced VSMCs fail to arrest growth at mitosis. (a) Cell-cycle analysis of DNA content in control and Akt1-overexpressing VSMCs. Cells were exponentially growing (0 population-doubling time [PDL]) or incubated with 100 ng/ml of colcemid for one or two PDLs (1, 2 PDL). Graphs show 104 cells. PDLs were 63 (β Gal), 58 (Akt1 wt), and 62 (Akt1 AA) hours. VSMCs were fixed in 70% ethanol, nuclei isolated, stained with propidium iodide, and processed for flow cytometry, as indicated in Methods. Graphs represent the distribution in 2N, 4N, and greater than 4N DNA content of 104 VSMCs per time point. (b) Akt1 causes VSMC polyploidization. VSMCs (WKY aorta, 3 weeks old) were transduced with the indicated moi’s of Akt1 wt adenovirus. Forty-eight hours after infection, cells were passed and incubated in new media with 100 ng/ml of colcemid for 72 hours. DNA content was determined by flow cytometry, as above. The figure indicates the percentage of VSMCs with greater than 4N DNA content. Data are representative of three experiments. (c) Flow cytometry analysis of total DNA content (propidium iodide staining) and newly synthesized DNA (BrdU incorporation) of VSMC-Akt1 wt cells incubated for two population-doubling times in the presence of 100 ng/ml of colcemid. Other experimental details as indicated in Methods. Data are representative of three experiments.