Velvet regulators as master integrators of development, metabolism, and pathogenicity in filamentous fungi

SUMMARY The velvet family of fungal regulatory proteins constitutes a unique and evolutionarily conserved set of transcriptional and epigenetic regulators that coordinate development, secondary metabolism, and pathogenicity in filamentous fungi. Among them, VeA, VelB, VelC, and VosA form dynamic protein complexes that act as molecular hubs, integrating environmental cues such as light and nutrient availability with intrinsic developmental signals. Over the past two decades, extensive genetic, molecular, and biochemical studies—particularly in Aspergillus species—have elucidated the central roles of these regulators in governing asexual and sexual development, spore viability, cell wall integrity, and the biosynthesis of secondary metabolites. Recent advances in genome-wide analyses, proteomics, and chromatin mapping have expanded our understanding of how velvet complexes influence chromatin architecture and coordinate transcriptional programs across fungal genomes. Velvet proteins not only regulate gene clusters involved in specialized metabolism but also control developmental transitions and stress responses, including those related to virulence in plant and human fungal pathogens. The interaction between LaeA—a methyltransferase—and velvet proteins further links transcriptional regulation to epigenetic control. This review synthesizes recent findings on the molecular functions, regulatory networks, and evolutionary conservation of velvet regulators, highlighting their emerging significance as master integrators in fungal biology. We also discuss knowledge gaps and future directions, including the therapeutic and biotechnological potential of targeting velvet-mediated regulation.