Tunicamycin-Induced Endoplasmic Reticulum Stress Damages Complex I in Cardiac Mitochondria

Area of Science:

• Mitochondrial biochemistry
• Cellular stress responses
• Cardiovascular research

Background:

• Endoplasmic reticulum (ER) stress can damage mitochondrial complex I.
• Thapsigargin-induced ER stress impairs complex I by increasing mitochondrial calcium.
• Tunicamycin (TUNI) is a known inducer of ER stress.

Purpose of the Study:

• To investigate if TUNI-induced ER stress leads to complex I damage in mouse hearts.
• To elucidate the mechanisms underlying TUNI-induced complex I dysfunction.

Main Methods:

• C57BL/6 mice were treated with TUNI (0.4 mg/kg) to induce ER stress.
• Cardiac mitochondria were isolated at 24 and 72 hours post-treatment.
• Mitochondrial function, complex I activity, subunit content, and calpain activation were assessed.

Main Results:

• TUNI treatment significantly increased ER stress at 72 hours.
• Complex I activity and oxidative phosphorylation were reduced in TUNI-treated mice.
• TUNI decreased levels of complex I subunits (NBUPL, NDUFS7) and activated calpain 1.

Conclusions:

• Tunicamycin-induced ER stress damages mitochondrial complex I.
• Calpain 1 activation is a key mediator of TUNI-induced complex I damage.
• Degradation of complex I subunits contributes to impaired mitochondrial function.