The Polyadenosine RNA Binding Protein ZC3H14 is Required in Mice for Proper Dendritic Spine Density

Abstract

ZC3H14 (Zinc finger CysCysCysHis domain-containing protein 14), an evolutionarily conserved member of a class of tandem zinc finger (CCCH) polyadenosine (polyA) RNA binding proteins, is associated with a form of heritable, nonsyndromic autosomal recessive intellectual disability. Previous studies of a loss of function mouse model, Zc3h14Δex13/Δex13, provide evidence that ZC3H14 is essential for proper brain function, specifically for working memory. To expand on these findings, we analyzed the dendrites and dendritic spines of hippocampal neurons from Zc3h14Δex13/Δex13 mice, both in situ and in vitro. These studies reveal that loss of ZC3H14 is associated with a decrease in total spine density in hippocampal neurons in vitro as well as in the dentate gyrus of 5-month old mice analyzed in situ. This reduction in spine density in vitro results from a decrease in the number of mushroom-shaped spines, which is rescued by exogenous expression of ZC3H14. We next performed biochemical analyses of synaptosomes prepared from whole wild-type and Zc3h14Δex13/Δex13 mouse brains to determine if there are changes in steady state levels of postsynaptic proteins upon loss of ZC3H14. We found that ZC3H14 is present within synaptosomes and that a crucial postsynaptic protein, CaMKIIα, is significantly increased in these synaptosomal fractions upon loss of ZC3H14. Together, these results demonstrate that ZC3H14 is necessary for proper dendritic spine density in cultured hippocampal neurons and in some regions of the mouse brain. These findings provide insight into how a ubiquitously expressed RNA binding protein leads to neuronal-specific defects that result in brain dysfunction.

The Drosophila RNA binding protein Nab2 patterns dendritic arbors and axons via the planar cell polarity pathway

“…Many phenotypes are conserved from Nab2 ex3 flies to Zc3h14 ∆13/∆13 mice including defects in working memory (KELLY et al 2016;BIENKOWSKI et al 2017;RHA et al 2017), a subset of proteomic changes in the brain (RHA et al 2017;CORGIAT et al 2021), anddefects in dendritic morphology (this study andJONES et al 2021). Nab2 has strong genetic interactions with PCP components, as shown here, but also has PCP-like defects in orientation of the fly wing hair bristles, a classic PCP phenotype (ADLER 2012;OLOFSSON AND AXELROD 2014;LEE et al 2020).…”

“…Loss of murine Zc3h14 causes defects in dendritic spine morphology among hippocampal neurons (JONES et al 2021) prompted us to test whether Nab2-PCP interactions in axons are also conserved in developing dendrites. For this approach, we visualized dendrites of Drosophila class IV dorsal dendritic arbor C (ddaC) neurons located in the larval body wall using a pickpocket (ppk)-Gal4,UAS-GFP system and quantified branching using Sholl intersection analysis (Fig.…”

“…Significantly, transgenic expression of human ZC3H14 only in fly neurons is sufficient to rescue a variety of Nab2 null phenotypes (PAK et al 2011;KELLY et al 2014;KELLY et al 2016), supporting a model in which Nab2 and ZC3H14 share critical molecular roles and mRNA targets. The Zc3h14 gene is not essential in mice but its loss results in defects in working memory (RHA et al 2017) and dendritic spine morphology (JONES et al 2021). An accompanying proteomic analysis of Zc3h14 knockout hippocampi identified several proteins involved in synaptic development and function that change in abundance upon ZC3H14 loss (RHA et al 2017), and which are thus candidates to contribute to Zc3h14 mutant phenotypes.…”

The RNA-binding protein Nab2 regulates the proteome of the developing Drosophila brain

“…The former link to axonogenesis matches the observed MB α-and β-lobe defects, but the latter link to dendritic proteins is more novel and may be conserved. The murine Nab2 homolog, ZC3H14, localizes to dendritic shafts and spines and controls dendritic spine morphology in cultured neurons (21,42). Nab2-regulated proteins identified in the current study that have predicted dendritic roles include the planar cell polarity factor Vang, the adhesion protein Cortactin, the netrin receptor Frazzled, the neuronal Ig-family transmembrane protein Turtle, the Fragile-X mental retardation homolog Fmr1, the Rho GEF Trio, the RNA binding protein Alan Shepherd/RBMS3, and the microtubule associated protein Futsch (MAP1ß).…”

The RNA binding protein Nab2 regulates the proteome of the developingDrosophilabrain

“…The former link to axonogenesis matches the observed MB α and β-lobe defects, but the latter link to dendritic proteins is more novel and may be conserved. The murine Nab2 homolog, Zc3h14, localizes to dendritic shafts and spines and controls spine morphology in cultured neurons (21, 38). Nab2-regulated proteins identified in the current study that have predicted dendritic roles include the planar cell polarity factor Vang, the adhesion protein Cortactin, the netrin receptor Frazzled, the neuronal Ig-family transmembrane protein Turtle, the Fragile-X mental retardation homolog Fmr1, the Rho GEF Trio, the RNA binding protein Alan Shepherd/RBMS3, and the microtubule associated protein Futsch (MAP1β).…”