Plasma Membrane Proteolipid 3 Protein Modulates Amphotericin B Resistance through Sphingolipid Biosynthetic Pathway

Area of Science:

• Mycology
• Molecular Biology
• Drug Resistance

Background:

• Invasive fungal infections pose a significant threat, particularly to immunocompromised individuals, often leading to high mortality.
• Amphotericin B (AmB) is a critical antifungal agent, but its efficacy is challenged by emerging resistance mechanisms.
• Known AmB resistance involves changes in ergosterol or cell wall composition, while sphingolipid depletion increases sensitivity.

Purpose of the Study:

• To elucidate the mechanistic basis by which the PMP3 gene affects Amphotericin B (AmB) resistance.
• To investigate the role of the sphingolipid pathway in PMP3-mediated modulation of AmB resistance.

Main Methods:

• Gene expression analysis of PMP3 and its impact on AmB resistance.
• Assessment of ergosterol content and cell wall integrity in relation to PMP3.
• Phenotypic analysis of PMP3 deletion strains, including actin polarity, salt tolerance, and endocytosis.
• Investigation of sphingolipid pathway intermediates, such as phytosphingosine, to modulate AmB sensitivity.

Main Results:

• PMP3's effect on AmB resistance is independent of ergosterol content and cell wall integrity.
• Observed phenotypes in PMP3 deletion strains (actin polarity, salt tolerance, endocytosis) do not correlate with AmB sensitivity.
• PMP3 overexpression-induced AmB resistance necessitates a functional sphingolipid pathway.
• AmB sensitivity in PMP3 deletion strains is restored by adding phytosphingosine, a sphingolipid intermediate.

Conclusions:

• The PMP3 gene modulates Amphotericin B resistance through a mechanism dependent on the sphingolipid pathway.
• Targeting the sphingolipid pathway in conjunction with PMP3 presents a potential strategy for enhancing antifungal therapies against opportunistic fungal infections.