Abstract
Unc-51 Like Kinase 1 (ULK1) is a critical regulator of the biogenesis of autophagosomes, the central component of the catabolic macroautophagy pathway. Regulation of ULK1 activity is dependent upon several phosphorylation events acting to repress or activate the enzymatic function of this protein. Phosphorylation of Ser758 ULK1 has been linked to repression of autophagosome biogenesis and was thought to be exclusively dependent upon mTOR complex 1 kinase activity. In the present study, a novel regulation of Ser758 ULK1 phosphorylation is reported following prolonged inhibition of the Parkinson’s disease linked protein leucine rich repeat kinase 2 (LRRK2). Here, modulation of Ser758 ULK1 phosphorylation following LRRK2 inhibition is decoupled from the repression of autophagosome biogenesis and independent of mTOR complex 1 activity.
Highlights
Macroautophagy is a critical eukaryotic catabolic pathway, conserved from yeast through to humans that allows the collection and degradation of cellular waste and contributes to maintenance of homoeostasis [1]
No increase in LC3-II or Ser758 Unc-51 like kinase 1 (ULK1) phosphorylation was recorded after adenosine monophosphate-activated protein kinase (AMPK) activation at variance with the results obtained using leucine rich repeat kinase 2 (LRRK2) inhibitors (Supplementary Figure S2)
A similar increase in Ser758 ULK1 phosphorylation was seen as a result of LRRK2 knockdown; when LRRK2 knockdown cells were treated with LRRK2-in1 (Figure 2 and Supplementary Figure S3) or MLi-2 (Supplementary Figure S1), no further increase in Ser758 ULK1 phosphorylation was detected
Summary
Macroautophagy is a critical eukaryotic catabolic pathway, conserved from yeast through to humans that allows the collection and degradation of cellular waste and contributes to maintenance of homoeostasis [1]. As previously reported by our group, inhibition of the kinase activity of LRRK2 in the H4 astroglioma cell line results in mTORC1 independent induction of macroautophagy [16,19].
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