Signaling of Infectious Growth in Fusarium oxysporum

Abstract

Infection-related development in fungal pathogens is regulated by a complex network of signaling pathways. In the vascular wilt fungus Fusarium oxysporum, the highly conserved mitogen-activated protein kinase (MAPK) Fmk1 controls invasive growth and virulence via the homeodomain transcription factor Ste12. Recently, the transmembrane mucin Msb2 was identified as a new component functioning upstream of this MAPK cascade in the process of host recognition and invasive growth. Signaling mucins contain a highly glycosylated extracellular domain, a single transmembrane region, and a short cytoplasmic tail. They have been extensively studied in mammalian cells as cell receptors functioning upstream of cancer-related MAPK pathways. In fungal pathogens of plants and humans, transmembrane mucins have recently emerged as novel virulence factors with a role in MAPK signaling and infection-related morphogenesis. In this chapter, we highlight the importance of these findings and discuss open questions on the mechanism of signal sensing and transmission by membrane mucins, as well as their relevance in the regulation of pathogenic development of fungi.