Sirtuin 3 deficiency does not augment hypoxia-induced pulmonary hypertension

Area of Science:

• Cardiovascular Physiology
• Mitochondrial Biology
• Cellular Signaling

Background:

• Alveolar hypoxia triggers mitochondrial reactive oxygen species (ROS) in pulmonary arterial smooth muscle cells (PASMCs), leading to hypoxic pulmonary vasoconstriction.
• Sirtuin 3 (Sirt3) deficiency is linked to enhanced ROS signaling and hypoxia-inducible factor (HIF)-1 activation in some cell types.
• Sirt3 is a mitochondrial deacetylase crucial for cellular metabolism and stress response.

Purpose of the Study:

• To investigate if Sirt3 deletion exacerbates hypoxia-induced ROS signaling in PASMCs.
• To determine if Sirt3 deficiency promotes the development of pulmonary hypertension (PH) and right ventricular hypertrophy under hypoxic conditions.

Main Methods:

• Utilized Sirt3 knockout (Sirt3(-/-)) and wild-type (Sirt3(+/+)) mice on a C57BL/6 background.
• Measured ROS signaling using redox-sensitive fluorescent protein sensors (roGFP) in mitochondria and cytosol during acute and sustained hypoxia.
• Assessed HIF-1α stabilization and evaluated PH, pulmonary artery remodeling, and right ventricular hypertrophy in mice exposed to chronic hypoxia.

Main Results:

• Acute hypoxia did not induce differential ROS or cytosolic calcium signaling between Sirt3(-/-) and Sirt3(+/+) PASMCs.
• Sustained hypoxia augmented mitochondrial matrix ROS in Sirt3(-/-) PASMCs but not cytosolic ROS.
• Sirt3 deletion did not affect HIF-1α stabilization or exacerbate PH and right ventricular hypertrophy in mice under chronic hypoxia.

Conclusions:

• Sirt3 deletion does not augment hypoxia-induced ROS signaling in the cytosol of PASMCs.
• Sirt3 deficiency does not worsen the development of pulmonary hypertension or right ventricular hypertrophy in this genetic background.
• Sirt3's role in hypoxia response may be cell-type specific or dependent on the genetic background.