Minibrain kinase and calcineurin coordinate activity-dependent bulk endocytosis through synaptojanin

J Cell Biol. 2021 Dec 6;220(12):e202011028. doi: 10.1083/jcb.202011028. Epub 2021 Oct 1.

Abstract

Neurons use multiple modes of endocytosis, including clathrin-mediated endocytosis (CME) and activity-dependent bulk endocytosis (ADBE), during mild and intense neuronal activity, respectively, to maintain stable neurotransmission. While molecular players modulating CME are well characterized, factors regulating ADBE and mechanisms coordinating CME and ADBE activations remain poorly understood. Here we report that Minibrain/DYRK1A (Mnb), a kinase mutated in autism and up-regulated in Down's syndrome, plays a novel role in suppressing ADBE. We demonstrate that Mnb, together with calcineurin, delicately coordinates CME and ADBE by controlling the phosphoinositol phosphatase activity of synaptojanin (Synj) during varying synaptic demands. Functional domain analyses reveal that Synj's 5'-phosphoinositol phosphatase activity suppresses ADBE, while SAC1 activity is required for efficient ADBE. Consequently, Parkinson's disease mutation in Synj's SAC1 domain impairs ADBE. These data identify Mnb and Synj as novel regulators of ADBE and further indicate that CME and ADBE are differentially governed by Synj's dual phosphatase domains.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Calcineurin / metabolism*
  • Clathrin / metabolism
  • Drosophila Proteins / metabolism*
  • Drosophila melanogaster / cytology*
  • Drosophila melanogaster / metabolism*
  • Endocytosis*
  • Nerve Tissue Proteins / metabolism*
  • Neurons / metabolism
  • Phosphoric Monoester Hydrolases / metabolism*
  • Phosphorylation
  • Phosphoserine / metabolism
  • Protein Serine-Threonine Kinases / metabolism*

Substances

  • Clathrin
  • Drosophila Proteins
  • Nerve Tissue Proteins
  • Phosphoserine
  • mnb protein, Drosophila
  • Protein Serine-Threonine Kinases
  • synaptojanin
  • Calcineurin
  • Phosphoric Monoester Hydrolases