ROCK1 and ROCK2 inhibition alters dendritic spine morphology in hippocampal neurons

Abstract

Communication among neurons is mediated through synaptic connections between axons and dendrites, and most excitatory synapses occur on actin-rich protrusions along dendrites called dendritic spines. Dendritic spines are structurally dynamic, and synapse strength is closely correlated with spine morphology. Abnormalities in the size, shape, and number of dendritic spines are prevalent in neurologic diseases, including autism spectrum disorders, schizophrenia, and Alzheimer disease. However, therapeutic targets that influence spine morphology are lacking. Rho-associated coiled-coil containing protein kinases (ROCK) 1 and ROCK2 are potent regulators of the actin cytoskeleton and highly promising drug targets for central nervous system disorders. In this report, we addressed how pharmacologic inhibition of ROCK1 and ROCK2 affects dendritic spine morphology. Hippocampal neurons were transfected with plasmids expressing fluorescently labeled Lifeact, a small actin binding peptide, and then incubated with or without Y-27632, an established pan-ROCK small molecule inhibitor. Using an automated 3D spine morphometry analysis method, we showed that inhibition of ROCK1 and ROCK2 significantly increased the mean protrusion density and significantly reduced the mean protrusion width. A trending increase in mean protrusion length was observed following Y-27632 treatment, and novel effects were observed among spine classes. Exposure to Y-27632 significantly increased the number of filopodia and thin spines, while the numbers of stubby and mushroom spines were similar to mock-treated samples. These findings support the hypothesis that pharmacologic inhibition of ROCK1 and ROCK2 may convey therapeutic benefit for neurologic disorders that feature dendritic spine loss or aberrant structural plasticity.

Dendritic spines provide cognitive resilience against Alzheimer's disease

“…The D’Agostino & Pearson omnibus normality test identified that these spine morphology parameters were not normally distributed, so non-parametric Kolmogorov-Smirnov tests were used. Two-sample Kolmogorov-Smirnov tests compared the frequency of spine morphology among spine populations between each pair of conditions 25, 26 . Additionally, one-way ANOVA with Tukey Post-hoc was performed to compare morphology among conditions.…”

Rho‐associated protein kinases as therapeutic targets for both vascular and parenchymal pathologies in Alzheimer's disease

“…; Koleske ; Swanger et al . ). The fine balance between activity of ROCKs and dendritic/synaptic functions is best demonstrated in a study using aged non‐transgenic rats, where treatment with fasudil alone was sufficient to improve spatial learning and working memory (Huentelman et al .…”

“…As a key regulator of cytoskeletal proteins, ROCK1/ROCK2 activity is crucial for the structural maintenance of neuronal processes which underlie synaptic transmission and cognitive functions. Over-activation of ROCKs can destabilize dendrites, whereas inhibition of ROCKs can promote neurite sprouting and regeneration (Nakayama et al 2000;Chen and Firestein 2007;Lingor et al 2007;Amano et al 2010;Koleske 2013;Swanger et al 2015). The fine balance between activity of ROCKs and dendritic/synaptic functions is best demonstrated in a study using aged non-transgenic rats, where treatment with fasudil alone was sufficient to improve spatial learning and working memory (Huentelman et al 2009).…”

Glucocorticoid receptors signaling impairment potentiates amyloid‐β oligomers‐induced pathology in an acute model of Alzheimer’s disease

“…[62][63][64] They have been suggested as potential therapeutic targets for neurodegenerative diseases, including AD. These Ser/Thr kinases are involved in cell motility, cell proliferation, autophagy, and apoptosis.…”