Characterizing the functional impact of novel mutations linked to autism spectrum disorder (ASD) provides a deeper mechanistic understanding of the underlying pathophysiological mechanisms. Here we show that a de novo Glu183 to Val (E183V) mutation in the CaMKII␣ catalytic domain, identified in a proband diagnosed with ASD, decreases both CaMKII␣ substrate phosphorylation and regulatory autophosphorylation, and that the mutated kinase acts in a dominant-negative manner to reduce CaMKII␣-WT autophosphorylation. The E183V mutation also reduces CaMKII␣ binding to established ASD-linked proteins, such as Shank3 and subunits of L-type calcium channels and NMDA receptors, and increases CaMKII␣ turnover in intact cells. In cultured neurons, the E183V mutation reduces CaMKII␣ targeting to dendritic spines. Moreover, neuronal expression of CaMKII␣-E183V increases dendritic arborization and decreases both dendritic spine density and excitatory synaptic transmission. Mice with a knock-in CaMKII␣-E183V mutation have lower total forebrain CaMKII␣ levels, with reduced targeting to synaptic subcellular fractions. The CaMKII␣-E183V mice also display aberrant behavioral phenotypes, including hyperactivity, social interaction deficits, and increased repetitive behaviors. Together, these data suggest that CaMKII␣ plays a previously unappreciated role in ASD-related synaptic and behavioral phenotypes.

These data suggest a role for 2-AG deficiency in social deficits and repetitive behavior, and they demonstrate a key role for 2-AG in regulating striatal direct-pathway MSNs.

The neurotransmitter dopamine (DA) regulates multiple behaviors across phylogeny, with disrupted DA signaling in humans associated with addiction, attention-deficit/ hyperactivity disorder, schizophrenia, and Parkinson's disease. The DA transporter (DAT) imposes spatial and temporal limits on DA action, and provides for presynaptic DA recycling to replenish neurotransmitter pools. Molecular mechanisms that regulate DAT expression, trafficking, and function, particularly , remain poorly understood, though recent studies have implicated rho-linked pathways in psychostimulant action. To identify genes that dictate the ability of DAT to sustain normal levels of DA clearance, we pursued a forward genetic screen in based on the phenotype swimming-induced paralysis (Swip), a paralytic behavior observed in hermaphrodite worms with loss-of-function mutations. Here, we report the identity of, which encodes a highly conserved ortholog of the human atypical MAP kinase ERK8. We present evidence that SWIP-13 acts presynaptically to insure adequate levels of surface DAT expression and DA clearance. Moreover, we provide and evidence supporting a conserved pathway involving SWIP-13/ERK8 activation of Rho GTPases that dictates DAT surface expression and function. Signaling by the neurotransmitter dopamine (DA) is tightly regulated by the DA transporter (DAT), insuring efficient DA clearance after release. Molecular networks that regulate DAT are poorly understood, particularly Using a forward genetic screen in the nematode, we implicate the atypical mitogen activated protein kinase, SWIP-13, in DAT regulation. Moreover, we provide and evidence that SWIP-13, as well as its human counterpart ERK8, regulate DAT surface availability via the activation of Rho proteins. Our findings implicate a novel pathway that regulates DA synaptic availability and that may contribute to risk for disorders linked to perturbed DA signaling. Targeting this pathway may be of value in the development of therapeutics in such disorders.

Neuronal excitation can induce new mRNA transcription, a phenomenon called excitation-transcription (E-T) coupling. Among several pathways implicated in E-T coupling, activation of voltage-gated L-type Ca channels (LTCCs) in the plasma membrane can initiate a signaling pathway that ultimately increases nuclear CREB phosphorylation and, in most cases, expression of immediate early genes. Initiation of this long-range pathway has been shown to require recruitment of Ca-sensitive enzymes to a nanodomain in the immediate vicinity of the LTCC by an unknown mechanism. Here, we show that activated Ca/calmodulin-dependent protein kinase II (CaMKII) strongly interacts with a novel binding motif in the N-terminal domain of Ca1 LTCC α1 subunits that is not conserved in Ca2 or Ca3 voltage-gated Ca channel subunits. Mutations in the Ca1.3 α1 subunit N-terminal domain or in the CaMKII catalytic domain that largely prevent the interaction also disrupt CaMKII association with intact LTCC complexes isolated by immunoprecipitation. Furthermore, these same mutations interfere with E-T coupling in cultured hippocampal neurons. Taken together, our findings define a novel molecular interaction with the neuronal LTCC that is required for the initiation of a long-range signal to the nucleus that is critical for learning and memory.

Ca 21 /calmodulin-dependent protein kinase II (CaMKII) and metabotropic glutamate receptor 5 (mGlu 5 ) are critical signaling molecules in synaptic plasticity and learning/memory. Here, we demonstrate that mGlu 5 is present in CaMKIIa complexes isolated from mouse forebrain. Further in vitro characterization showed that the membrane-proximal region of the C-terminal domain (CTD) of mGlu 5a directly interacts with purified Thr286-autophosphorylated (activated) CaMKIIa. However, the binding of CaMKIIa to this CTD fragment is reduced by the addition of excess Ca 21 /calmodulin or by additional CaMKIIa autophosphorylation at non-Thr286 sites. Furthermore, in vitro binding of CaMKIIa is dependent on a tribasic residue motif Lys-Arg-Arg (KRR) at residues 866-868 of the mGlu 5a -CTD, and mutation of this motif decreases the coimmunoprecipitation of CaMKIIa with full-length mGlu 5a expressed in heterologous cells by about 50%. The KRR motif is required for two novel functional effects of coexpressing constitutively active CaMKIIa with mGlu 5a in heterologous cells. First, cell-surface biotinylation studies showed that CaMKIIa increases the surface expression of mGlu 5a . Second, using Ca 21 fluorimetry and single-cell Ca 21 imaging, we found that CaMKIIa reduces the initial peak of mGlu 5a -mediated Ca 21 mobilization by about 25% while doubling the relative duration of the Ca 21 signal. These findings provide new insights into the physical and functional coupling of these key regulators of postsynaptic signaling. [DK020593], and the Center for Stem Cell Biology. https://doi.org/10. 1124/mol.118.113142. s This article has supplemental material available at molpharm. aspetjournals.org.