RT Journal Article SR Electronic T1 Loss of NDR1/2 kinases impairs endomembrane trafficking and autophagy leading to neurodegeneration JF Life Science Alliance JO Life Sci. Alliance FD Life Science Alliance LLC SP e202201712 DO 10.26508/lsa.202201712 VO 6 IS 2 A1 Flavia Roşianu A1 Simeon R Mihaylov A1 Noreen Eder A1 Antonie Martiniuc A1 Suzanne Claxton A1 Helen R Flynn A1 Shamsinar Jalal A1 Marie-Charlotte Domart A1 Lucy Collinson A1 Mark Skehel A1 Ambrosius P Snijders A1 Matthias Krause A1 Sharon A Tooze A1 Sila K Ultanir YR 2023 UL https://www.life-science-alliance.org/content/6/2/e202201712.abstract AB Autophagy is essential for neuronal development and its deregulation contributes to neurodegenerative diseases. NDR1 and NDR2 are highly conserved kinases, implicated in neuronal development, mitochondrial health and autophagy, but how they affect mammalian brain development in vivo is not known. Using single and double Ndr1/2 knockout mouse models, we show that only dual loss of Ndr1/2 in neurons causes neurodegeneration. This phenotype was present when NDR kinases were deleted both during embryonic development, as well as in adult mice. Proteomic and phosphoproteomic comparisons between Ndr1/2 knockout and control brains revealed novel kinase substrates and indicated that endocytosis is significantly affected in the absence of NDR1/2. We validated the endocytic protein Raph1/Lpd1, as a novel NDR1/2 substrate, and showed that both NDR1/2 and Raph1 are critical for endocytosis and membrane recycling. In NDR1/2 knockout brains, we observed prominent accumulation of transferrin receptor, p62 and ubiquitinated proteins, indicative of a major impairment of protein homeostasis. Furthermore, the levels of LC3-positive autophagosomes were reduced in knockout neurons, implying that reduced autophagy efficiency mediates p62 accumulation and neurotoxicity. Mechanistically, pronounced mislocalisation of the transmembrane autophagy protein ATG9A at the neuronal periphery, impaired axonal ATG9A trafficking and increased ATG9A surface levels further confirm defects in membrane trafficking, and could underlie the impairment in autophagy. We provide novel insight into the roles of NDR1/2 kinases in maintaining neuronal health.