Exogenous cardiolipin localizes to mitochondria and prevents TAZ knockdown-induced apoptosis in myeloid progenitor cells

Abstract

The concentration and composition of cardiolipin (CL) in mitochondria are altered in age-related heart disease, Barth Syndrome, and other rare genetic disorders, resulting in mitochondrial dysfunction. To explore whether exogenous CL can be delivered to cells, CL was combined with apolipoprotein A-I to generate water-soluble, nanoscale complexes termed nanodisks (ND). Mass spectrometry HL60 myeloid progenitor cell extracts revealed a 30-fold increase in cellular CL content following incubation with CL-ND. When CL-ND containing a fluorescent CL analogue was employed, confocal microscopy revealed CL localization to mitochondria. The ability of CL-ND to elicit a physiological response was examined in an HL60 cell culture model of Barth Syndrome neutropenia. siRNA knockdown of the phospholipid transacylase, tafazzin (TAZ), induced apoptosis in these cells. When TAZ knockdown cells were incubated with CL-ND, the apoptotic response was attenuated. Thus, CL-ND represent a potential intervention strategy for replenishment of CL in Barth Syndrome, age-related heart disease, and other disorders characterized by depletion of this key mitochondrial phospholipid.

Evaluation of cardiolipin nanodisks as lipid replacement therapy for Barth syndrome

“…The prepared lipid was dispersed in PBS (20 mmol/L sodium phosphate, 150 mmol/L sodium chloride, pH 7.0) followed by the addition of 2 mg recombinant murine apolipoprotein (apo) A-I [ 20 ] in a final volume of 0.55 mL. Bath sonication of the turbid CL-apoA-I mixture induced sample clearance, an indication that CL-ND had formed [ 16 ] . CL-ND preparations were sterile-filtered (0.22 µm) prior to administration to mice.…”

“…When these cells were transfected with a TAZ -specific short-hairpin RNA (shRNA), increased apoptosis was observed. Subsequently, in an attempt to bypass the deficiency, TAZ knockdown (KD) HL60 cells were incubated with CL nanodisks (ND), water soluble nanoscale particles formed upon incubation of an aqueous dispersion of tetralinoleoyl CL with an amphipathic apolipoprotein [ 14 – 16 ] . ND-mediated delivery of tetralinoleoyl CL to cultured TAZ KD HL60 cells delivered exogenous CL to mitochondria and attenuated the apoptotic response [ 16 ] .…”

Tafazzin Mutation Affecting Cardiolipin Leads to Increased Mitochondrial Superoxide Anions and Mitophagy Inhibition in Barth Syndrome

“…The mechanisms that lead from abnormal CL biogenesis to cardiomyopathy are not well understood. They include dysregulation or dysfunction of numerous processes that are related to oxidative phosphorylation [ 20 , 30 , 31 ], fission or fusion [ 21 , 32 , 33 ], iron–sulfur cluster biogenesis [ 34 ], protein import [ 18 , 22 ], apoptosis [ 35 , 36 , 37 , 38 , 39 , 40 , 41 ], autophagy [ 36 , 42 ], and transport of protein precursors across the mitochondrial membrane (in general metabolites) [ 18 , 23 , 43 , 44 , 45 , 46 , 47 , 48 , 49 ].…”

Assembly and Characterization of Biocompatible Coenzyme Q10‐Enriched Lipid Nanoparticles

“…The data reveal that both ND samples elute from the column in a single major peak, indicating a single particle population. Based on comparison of this elution profile with that of cardiolipin ND (Fox et al, 2019), which are 18-31 nm in diameter (Ikon et al, 2015), the data indicate that CoQ 10 ND have particle diameters in this range. Absorbance was monitored at 280 nm, with two components (apoA-I and CoQ 10 ) contributing to this signal in CoQ 10 ND and only one component contributing (apoA-I) in the empty ND.…”