Construction of mitochondrial-targeted ferritin carrier: subunit-terminal fused mitochondrial presequences facilitate...

Protein sorting within mitochondria is intricately linked to the amino acid sequence facilitating the transmembrane transport of proteins into this organelle. Leveraging the Mitochondrial Targeting Signal (MTS)-mediated protein sorting mechanism presents a promising strategy for directing therapeutic agents into the mitochondria.

By fusing MTS to the subunit terminus of recombinant heavy chain ferritin (HFn), we aim to establish a highly effective mitochondrial targeting vector. This fusion is designed to enhance the ability to specifically direct and accumulate within mitochondria, and to precisely deliver Lonidamine (LND), a selective metabolic inhibitor, into these organelles, ultimately realizing potent anti-tumor activity.

Utilizing gene engineering strategies, a plasmid encoding MTS-modified HFn (MTS-HFn) was transferred into E.coli to induce protein expression. At the cellular level, the mitochondrial targeting capacity of MTS-HFn was investigated. Subsequently, LND was encapsulated within MTS-HFn, and its tumoral accumulation and anti-tumor efficacy were studied in tumor-bearing models.

MTS-HFn demonstrated exceptional mitochondrial targeting, achieving a 2.7-fold higher accumulation in mitochondria compared to wild-type HFn. The targeting mechanism exploration unveiled that the positive charge of MTS drives aggregation of HFn around mitochondria, and mediates its entry into the mitochondrial matrix via the TOM/TIM complex. In vivo antitumor activity studies revealed that MTS-HFn preserved its inherent tumor targeting ability and significantly enhanced the tumor suppressive effect of LND, yielding an inhibition rate of 51.06%.

This vector inspired by natural mitochondrial protein sorting represents an optimal hierarchical delivery system for targeting both tumor and mitochondrial, offering a dependable alternative for precise treatment strategies in mitochondrial diseases.