A functional screen implicates microRNA-138-dependent regulation of the depalmitoylation enzyme APT1 in dendritic spine morphogenesis

Abstract

Summary The microRNA pathway has been implicated in the regulation of synaptic protein synthesis and ultimately dendritic spine morphogenesis, a phenomenon associated with long-lasting forms of memory. However, the particular microRNAs (miRNAs) involved are largely unknown. We performed a functional screen to identify specific miRNAs that function at synapses to control dendritic spine structure. One of the identified miRNAs, miR-138, is highly enriched in the brain, localized within dendrites and negatively regulates the size of dendritic spines in rat hippocampal neurons. miR-138 controls the expression of Acyl protein thioesterase 1 (APT1), an enzyme regulating the palmitoylation status of proteins that are known to function at the synapse, including G protein alpha subunits (Gα). RNAi-mediated knockdown of APT1 and expression of membrane-localized Gα both suppress spine enlargement caused by miR-138 inhibition, suggesting that APT1-regulated depalmitoylation of Gα might be an important downstream event of miR-138 function. Our results uncover a novel miRNA-dependent mechanism in neurons and demonstrate a previously unrecognized complexity of miRNA-dependent control of dendritic spine morphogenesis.

NMDAR ‐dependent Argonaute 2 phosphorylation regulates mi RNA activity and dendritic spine plasticity

“…We analysed two dendritically regulated UTRs; LIMK1 , which is regulated by miR‐134 (Schratt et al , 2006), and APT1 , which is regulated by miR‐138 (Siegel et al , 2009). Both of these miRNAs have been shown previously to regulate dendritic spine morphology (Schratt et al , 2006; Siegel et al , 2009), and we previously demonstrated that NMDAR activation increased translational repression of the LIMK1 reporter via miR‐134 and of the APT1 reporter via miR‐138 within 10 min after stimulation (Antoniou et al , 2014; Rajgor et al , 2017). Knockdown of Ago2 by shRNA caused a dramatic increase in expression of both reporter constructs, consistent with a deficit of miRNA‐mediated translational repression, and NMDAR stimulation had no effect under these conditions (Fig 5A and B).…”

MicroRNA-134 activity in somatostatin interneurons regulates H-Ras localization by repressing the palmitoylation enzyme, DHHC9

“…Several studies have suggested that microRNAs contribute to the establishment and maintenance of synaptic plasticity in developing and mature neurons (1,3,25,26). MicroRNAs regulated by neuronal activity are particularly suited for this role.…”

“…palmitoyltransferase | RISC-trap C onsiderable progress has been made in understanding the contributions of microRNAs to neuronal development, but microRNAs are also found in mature neurons, where their localization in dendrites, and possibly axons, has been proposed to contribute to synaptic plasticity (1)(2)(3)(4)(5). This is an appealing concept because local regulation of protein translation is essential for plasticity and microRNAs can regulate dendritic growth, spine formation, and growth cone guidance, properties generally believed to underlie plasticity.…”

MicroRNAs and synaptic plasticity—a mutual relationship

“…R. Soc. B 369: 20130515 spine growth by targeting APT1, suggesting that activitydependent miR-138 inactivation could be a mechanism of synaptic potentiation [39]. Muddashetty et al [40] investigated a possible function of FMRP in the dynamic control of miRNA function.…”