The Nucleoporin MLP1 of the nuclear basket is essential for nuclear integrity and ploidy maintenance in Trypanosoma brucei

Abstract

Trypanosoma brucei is a divergent eukaryote parasite responsible for neglected tropical diseases in human and animals, sleeping sickness or human African trypanosomiasis and nagana respectively. Besides scientific interest, understanding the specific features of its biology has medical and economical relevance. Nuclear pore complexes (NPCs) are large multiprotein channels embedded in the nuclear envelope that regulate nucleo-cytoplasmic transport. Beyond this role, NPCs also participate in essential nuclear processes such as chromosome segregation, transcription, and cytokinesis. Here, we showed that Myosin-like protein-1 (MLP1) localized to the nuclear basket of NPCs in T. brucei. Silencing of TbMLP1 by RNA interference in T. brucei procyclic cells caused marked defects in parasite growth, severe impairment of messenger RNA export, disorganization of nuclear structure, and pronounced genomic instability. Flow cytometry and FISH analyses revealed abnormal DNA content and a sharp reduction in disomic cells, accompanied by increased numbers of monosomic, trisomic, and polysomic cells, indicating an untolerated aneuploidy. These findings reveal that TbMLP1 links NPC function to multiple key cellular pathways. We provide new insights into the mechanisms that preserve nuclear architecture, nuclear envelope morphology, genome stability, and faithful chromosome segregation, including effects on kinetochore distribution and organization of the mitotic spindle. Author SummaryTrypanosoma brucei is the microscopic parasite responsible for sleeping sickness in humans and nagana in cattle; learning more about its basic biology may help identify weak points that could one day be targeted in new treatments. In this work, we studied a protein called MLP1, which sits at the nuclear pores--the gateways that control what enters and leaves the nucleus. Our findings revealed that MLP1 is essential for ensuring proper movement of messenger RNA, keeping the nucleus stable, and allowing chromosomes to be shared equally when cells divided. In total, we gained new insight into the basic biology of a parasite that remains a major health concern in many regions of the world, showing how a single structural protein can influence many vital processes within it.