Table1_Neurobehavioral characteristics of mice with SETD5 mutations as models of IDD23 and KBG syndromes.XLSX

Genomic analysis has revealed that the genes for various chromatin regulators are mutated in many individuals with neurodevelopmental disorders (NDDs), emphasizing the important role of chromatin regulation in nervous system development and function. Chromatin regulation is mediated by writers, readers, and erasers of histone and DNA modifications, with such proteins being defined by specific domains. One of these domains is the SET domain, which is present in enzymes that catalyze histone methylation. Heterozygous loss-of-function mutations of the SETD5 (SET domain containing 5) gene have been identified in individuals with an NDD designated IDD23 (intellectual developmental disorder, autosomal dominant 23). KBG syndrome (named after the initials of the last names of the first three families identified with the condition) is characterized by features that either overlap with or are distinct from those of IDD23 and was initially thought to be caused only by mutations in the ANKRD11 (ankyrin repeat domain containing 11) gene. However, recent studies have identified SETD5 mutations in some KBG syndrome patients without ANKRD11 mutations. Here we summarize the neurobehavioral characterization of Setd5+/− mice performed by four independent research groups, compare IDD23 and KBG phenotypes, and address the utility and future development of mouse models for elucidation of the mechanisms underlying NDD pathogenesis, with a focus on SETD5 and its related proteins.</p

Image1_Neurobehavioral characteristics of mice with SETD5 mutations as models of IDD23 and KBG syndromes.PDF

Genomic analysis has revealed that the genes for various chromatin regulators are mutated in many individuals with neurodevelopmental disorders (NDDs), emphasizing the important role of chromatin regulation in nervous system development and function. Chromatin regulation is mediated by writers, readers, and erasers of histone and DNA modifications, with such proteins being defined by specific domains. One of these domains is the SET domain, which is present in enzymes that catalyze histone methylation. Heterozygous loss-of-function mutations of the SETD5 (SET domain containing 5) gene have been identified in individuals with an NDD designated IDD23 (intellectual developmental disorder, autosomal dominant 23). KBG syndrome (named after the initials of the last names of the first three families identified with the condition) is characterized by features that either overlap with or are distinct from those of IDD23 and was initially thought to be caused only by mutations in the ANKRD11 (ankyrin repeat domain containing 11) gene. However, recent studies have identified SETD5 mutations in some KBG syndrome patients without ANKRD11 mutations. Here we summarize the neurobehavioral characterization of Setd5+/− mice performed by four independent research groups, compare IDD23 and KBG phenotypes, and address the utility and future development of mouse models for elucidation of the mechanisms underlying NDD pathogenesis, with a focus on SETD5 and its related proteins.</p

Epiregulin (EPR) and amphiregulin (AR) inhibited cell death in Neuro2a cells.

<p>The cells were pretreated with EPR (0.01, 0.03, 0.1, and 1 nM) and AR (0.001, 0.01, 0.03, 0.1, and 1 nM) for 1 h and subsequently treated according to the indicated conditions. (A) EPR reduced the release of lactate dehydrogenase (LDH) at 48 h after Tm (1 μg/mL) treatment. (B) AR reduced the release of LDH at 48 h after Tm (1 μg/mL) treatment. The LDH released into the medium was expressed as a percentage of the control value. The data represent the average of 4 independent experiments for each sample. *p < 0.05.</p

Stress-Induced Neuroprotective Effects of Epiregulin and Amphiregulin

<div><p>Members of the epidermal growth factor family play important roles in the regulation of cell growth, proliferation, and survival. However, the specific roles of each epidermal growth factor family member with respect to brain injury are not well understood. Gene chip assay screens have revealed drastic increases in the expression of the epidermal growth factor family members amphiregulin and epiregulin following lipopolysaccharide stimulation, which activates an immune response. Both immune activity and endoplasmic reticulum stress are activated during cerebral ischemia. We found that the expression levels of amphiregulin and epiregulin were significantly increased under conditions of cerebral ischemia. Because endoplasmic reticulum stress increased the expression of amphiregulin and epiregulin in glial cells, endoplasmic reticulum stress may be a key mediatory factor of pathophysiological activity. Recombinant epiregulin and amphiregulin proteins effectively inhibited endoplasmic reticulum stress and the subsequent induction of neuronal cell death. Therefore, the upregulation of the epidermal growth factor family members epiregulin and amphiregulin may play a critical role in preventing endoplasmic reticulum stress-induced cell death, thus providing a potential therapy for brain injury.</p></div

Fold changes in EGF family member expression following LPS stimulation.

<p>Fold changes in EGF family member expression following LPS stimulation.</p

Epiregulin (EPR) and amphiregulin (AR) inhibited cell death in Neuro2a cells.

<p>The cells were pretreated with EPR (0.01, 0.03, 0.1, and 1 nM) and AR (0.001, 0.01, 0.03, 0.1, and 1 nM) for 1 h and subsequently treated according to the indicated conditions. (A) EPR reduced the release of lactate dehydrogenase (LDH) at 48 h after Tm (1 μg/mL) treatment. (B) AR reduced the release of LDH at 48 h after Tm (1 μg/mL) treatment. The LDH released into the medium was expressed as a percentage of the control value. The data represent the average of 4 independent experiments for each sample. *p < 0.05.</p

Increased circulating levels of insulin and leptin in MyD88-deficient mice.

<p>(<b>A</b>) Plasma insulin was measured in each genotype fed the NCD (n = 9–10) or HFD (n = 10–15) at the age of 16 weeks. *<i>p</i><0.05 (<b>B</b>) Plasma leptin was measured in each genotype fed the NCD (n = 9–16) or HFD (n = 11–12) at the age of 16 weeks. **<i>p</i><0.01, ***<i>p</i><0.001.</p

MyD88-deficiency increases the risk of diabetic mellitus.

<p>Both genotypes were fed a NCD until 6 weeks of age and then fed a NCD or HFD for 10 weeks. Mice were fasted for 16 h (from 18:00 to 10:00) and subjected to a glucose tolerance test (GTT). We measured circulating levels of glucose at the time indicated (0.5-4 h). (<b>A</b>) NCD-fed mice. (<b>B</b>) HFD-fed mice. (<b>C</b>) NCD- and HFD-fed mice, which were fasted for 16 h. (<b>D</b>) Glucose levels after GTT (2 h time point) of each genotype of mice fed the NCD or HFD. n = 6∼12/group. *<i>p</i><0.05, **<i>p</i><0.01, ***<i>p</i><0.001 v.s. control mice.</p

Induction of epiregulin (EPR) and amphiregulin (AR) mRNA expression in primary glial cells following Tm treatment.

<p>Total RNA was isolated from cells exposed to Tm (3 μg/ml) for the indicated periods and subjected to RT-PCR. Data are presented as the means ± standard errors from 3 separate experiments. *p < 0.05 compared with the control.</p

Induction of epiregulin (EPR) and amphiregulin (AR) mRNA expression in primary glial cells under hypoxic conditions.

<p>Total RNA was isolated from cells exposed to hypoxic conditions for the indicated time periods and subjected to RT-PCR. Data are presented as the means ± standard errors from 3 separate experiments. *p < 0.05 compared with the control.</p