Cytoplasmic-predominant Pten increases microglial activation and synaptic pruning in a murine model with autism-like phenotype

Abstract

Germline mutations in PTEN account for~10% of cases of autism spectrum disorder (ASD) with coincident macrocephaly. To explore the importance of nuclear PTEN in the development of ASD and macrocephaly, we previously generated a mouse model with predominantly cytoplasmic localization of Pten (Pten m3m4/m3m4).Cytoplasmic predominant Pten localization results in a phenotype of extreme macrocephaly and autistic-like traits. Transcriptomic analysis of the Pten m3m4/m3m4 cortex found upregulated gene pathways related to myeloid cell activation, myeloid cell migration, and phagocytosis. These transcriptomic findings were used to direct in vitro assays on Pten wild-type and Pten m3m4/m3m4 microglia. We found increased Iba1 and C1q expression with enhanced phagocytic capacity in Pten m3m4/m3m4 microglia, indicating microglial activation. Moreover, through a series of neuron-microglia co-culture experiments, we found Pten m3m4/m3m4 microglia are more efficient at synaptic pruning compared with wild-type controls. In addition, we found evidence for neuron-microglia cross-talk, where Pten m3m4/m3m4 neurons elicit enhanced pruning from innately activated microglia. Subsequent in vivo studies validated our in vitro findings. We observed a concurrent decline in the expression of Pten and synaptic markers in the Pten m3m4/m3m4 cortex. At~3 weeks of age, with a 50% drop in Pten expression compared with wild-type levels, we observed enhanced activation of microglia in the Pten m3m4/m3m4 brain. Collectively, our data provide evidence that dysregulated Pten in microglia has an etiological role in microglial activation, phagocytosis, and synaptic pruning, creating avenues for future studies on the importance of PTEN in maintaining microglia homeostasis.

Transcriptome-(Phospho)proteome Characterization of the Brain of a Constitutional Model of Cytoplasmic-predominant Pten Expression With Autism-Like Phenotypes

“…3e). These predictions are largely consistent with previous observations in the Pten m3m4/m3m4 cortex [21,23,24]. The network analysis enables a biological understanding of the changes in protein expression and phosphorylation, which unequivocally point to disrupted Pten function in the brain and highlight its importance in propagating dysfunction to downstream effector molecules.…”

“…The Pten m3m4 murine model Our planned experimental procedures were approved by the Cleveland Clinic's Institutional Animal Care and Use Committee (IACUC) under protocol numbers 2018-1952 and 2017-1879 and guided by the Principles of Laboratory Animal Care formulated by the National Society for Medical Research. We created the Pten m3m4 mouse on an outbred CD1 background, which has been studied extensively, shown to have de cits in social behavior, changes in neuron and glia populations, and changes in gene expression in many known autism risk genes [21][22][23]25,26,29]. The Pten m3m4 mutation, located within exon 7 of mouse Pten, consists of ve nucleotide substitutions that results in four nonsynonymous and one synonymous codon changes.…”

Inhibition of Microglial Activation in the Amygdala Reverses Stress-Induced Abdominal Pain in the Male Rat

“…Microglia contact and survey dendrite synapses in the healthy brain to maintain the proper function of synapses in neuron–neuron communication, whereas in the diseased brain, activated microglia have been associated with the loss of synapses. 20 , 28 , 60 , 61 , 62 , 63 In our model, increased microglial engulfment of synaptic spines in the CeA combined with the observation of increased visceral sensitivity suggested an association between microglia-mediated neuronal remodeling in the CeA with the development of visceral hypersensitivity after exposure to chronic stress. In support, minocycline infusion into the CeA decreased microglia-mediated synaptic remodeling and decreased the visceromotor behavioral response to luminal distension, which further suggests a relationship between the functional plasticity of amygdala microglia with stress-induced visceral pain.…”

Germline Nuclear-predominant Pten Murine Model Exhibits Impaired Social and Perseverative Behavior, Microglial Activation, and Increased Oxytocinergic Activity

“…Microglial activation in the brains of Pten Y68H/+ mice It has been well established that disrupted Pten expression in mice can lead to increased cellular proliferation, white matter abnormality, astrogliosis, and microglial activation in vivo [16,23,30,31]. Therefore, we sought to determine if there were any clear cellular pathologies in the brains of six-month-old Pten Y68H/+ mice, using immuno uorescence staining and Western blotting for markers speci c to neurons, oligodendrocytes, astrocytes, and microglia.…”