Identification of a Ste20-like kinase-dependent network orchestrating cytoskeletal and synaptic development of cortical neurons. Untargeted phosphorylation analysis

ABSTRACT: The Ste20-like kinase (Slk) is a serine/threonine kinase that regulates cytoskeletal organization, apoptosis, and cell polarity in non-neuronal cells. In neurons, Slk guides dendrite morphogenesis and inhibitory synapse stability, controlling excitation-inhibition balance through parvalbumin interneuron function. Almost complete loss of Slk in dysmorphic neurons of epileptogenic cortical dysplasias implicates a function of this kinase in neurodevelopmental disorders. However, its neuronal signaling mechanisms remain poorly understood. Here, we mapped Slk signaling in cortical neurons by pairing affinity purification-mass spectrometry with quantitative phosphoproteomics to define the Slk interactome and phosphorylation landscape in cortical neurons. Across the two datasets, we identified hundreds of candidates and more than 1,000 regulated phosphosites after Slk knockdown. Slk is associated with a network of cytoskeletal and synaptic proteins, as loss of Slk changed the phosphorylation of proteins involved in actin and microtubule regulation, cell adhesion, and synaptic stability. We identified two GCK-family kinases, Mink1 and Tnik, as direct Slk substrates, with phosphorylation at the activation-loop threonine (T181), placing Slk upstream of a kinase cascade that controls dendritic growth. We also link Slk to intrinsic excitability by showing Slk-dependent phosphorylation of the M-current subunit Kcnq2 (Kv7.2) and a >50% reduction in spiking in Slk-deficient networks upon the Kcnq2 blocker ML252, with shorter bursts and fewer spikes per burst. Together, the dataset positions Slk upstream of cytoskeletal, synaptic, and excitability pathways in the developing cortex.

INSTRUMENT(S):

ORGANISM(S): Homo Sapiens (human) Mus Musculus (mouse)

SUBMITTER: Marc Sylvester  

LAB HEAD: Prof. Dr. Susanne Schoch

PROVIDER: PXD073661 | Pride | 2026-10-02

REPOSITORIES: Pride