dictyNews
Electronic Edition
Volume 49, number 1
January 6, 2023

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Abstracts
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Katnip is required to maintain microtubule function and lysosomal 
delivery to autophagosomes and phagosomes

Georgina P. Starling1, Ben A Philips1, Sahana Ganesh1 and 
Jason S. King1*.

1 Department of Biomedical Science, University of Sheffield  

*Corresponding author: [log in to unmask]


Molecular Biology of the Cell, in press
https://www.molbiolcell.org/doi/10.1091/mbc.E22-02-0063

The efficient delivery of lysosomes is essential for many cell 
functions, such as the degradation of unwanted intracellular 
components by autophagy and the killing and digestion of 
extracellular microbes within phagosomes. Using the amoeba 
Dictyostelium discoideum we find that cells lacking Katnip 
(Katanin interacting protein) have a general defect in lysosomal 
delivery and although they make autophagosomes and phagosomes 
correctly, cells are then unable to digest them. 

Katnip is largely unstudied yet highly conserved across evolution. 
Previously studies found Katnip mutations in animals cause defects 
in cilia structure. Here we show that Katnip plays a more general 
role in maintaining microtubule function. We find that loss of 
Katnip has no overall effect on microtubule dynamics or organisation, 
but is important for the transport and degradation of endocytic 
cargos. Strikingly, Katnip mutants become highly sensitive to 
GFP-tubulin expression, which leads to microtubule tangles, defective 
anaphase extension and slow cell growth. Our findings establish a 
general role for Katnip in regulating microtubule function, beyond 
the previous roles described in cilia. We speculate this is via a 
key function in microtubule repair, required to maintain endosomal 
trafficking and lysosomal degradation.


Submitted by Jason King [[log in to unmask]]
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