A brain somatic RHEB doublet mutation causes focal cortical dysplasia type II.

Focal cortical dysplasia type II (FCDII) is a cerebral cortex malformation characterized by local cortical structure disorganization, neuronal dysmorphology, and refractory epilepsy. Brain somatic mutations in several genes involved in the PI3K/AKT/mTOR pathway are associated with FCDII, but they are only found in a proportion of patients with FCDII. The genetic causes underlying the development FCDII in other patients remain unclear. Here, we carried out whole exome sequencing and targeted sequencing in paired brain-blood DNA from patients with FCDII and identified a brain somatic doublet mutation c.(A104T, C105A) in the Ras homolog, mTORC1 binding (RHEB) gene, which led to the RHEB p.Y35L mutation in one patient with FCDII. This RHEB mutation carrier had a dramatic increase of ribosomal protein S6 phosphorylation, indicating mTOR activation in the region of the brain lesion. The RHEB p.Y35L mutant protein had increased GTPλS-binding activity compared with wild-type RHEB. Overexpression of the RHEB p.Y35L variant in cultured cells also resulted in elevated S6 phosphorylation compared to wild-type RHEB. Importantly, in utero electroporation of the RHEB p.Y35L variant in mice induced S6 phosphorylation, cytomegalic neurons, dysregulated neuron migration, abnormal electroencephalogram, and seizures, all of which are found in patients with FCDII. Rapamycin treatment rescued abnormal electroencephalograms and alleviated seizures in these mice. These results demonstrate that brain somatic mutations in RHEB are also responsible for the pathogenesis of FCDII, indicating that aberrant activation of mTOR signaling is a primary driver and potential drug target for FCDII.

Development of new population-averaged standard templates for spatial normalization and segmentation of MR images for postnatal piglet brains.

PROPOSE: To design a set of brain templates for postnatal piglet brains based on high-resolution T1-weighted imaging for voxel-based morphometric analysis. MATERIALS AND METHODS: Using a 3.0 T magnetic resonance (MR) scanner, a population-based whole brain template was developed by averaging forty T1 images in the brains of postnatal piglets at 38 days of age. The templates for gray and white matter, and cerebrospinal fluid were designed based on the corresponding probability maps by adapting individual data sets using statistical parametric mapping. Anatomical labeling maps were generated from labeling propagation derived from the established Pig Brain Atlas. Differences in the coordinates from four significant structural landmarks in the template, plus an additional 12 normalized images and anatomical labeling maps were measured to validate the accuracy of the registration of the template. RESULTS: A whole brain template, a set of tissue-specific probability and anatomical labeling maps were developed. The location deviation of the four significant structural landmarks, including the anterior and posterior regions in the corpus callosum, and the left and right caudate nucleus, was found to be <0.25 cm, validating the sensitivity and resolution of the template. CONCLUSION: A whole brain template map and a set of tissue-specific probability and anatomical labeling maps were developed to analyze the morphometric imaging of the postnatal piglet brain, an animal model of the human infant.

Lactoferrin up-regulates intestinal gene expression of brain-derived neurotrophic factors BDNF, UCHL1 and alkaline phosphatase activity to alleviate early weaning diarrhea in postnatal piglets.

The molecular mechanisms underlying how dietary lactoferrin (Lf) impacts gut development and maturation and protects against early weaning diarrhea are not well understood. In this study, we supplemented postnatal piglets with an Lf at a dose level of 155 and 285 mg/kg/day from 3 to 38 days following birth. Our findings show that the high dose of Lf up-regulated messenger RNA expression levels of genes encoding brain-derived neurotrophic factor (BDNF) and ubiquitin carboxy-terminal hydrolase L1 (ubiquitin thiolesterase (UCHL1) and, to a lesser extent, glial cell line-derived neurotrophic factor, in the duodenum (P<.05). Piglets in the high and low Lf group had 30% and 7% larger jejunal crypts compared with the control group (P<.05). Escherichia coli 16S rRNA copy number per gram of ascending colon contents was significantly reduced (P=.001), while the copy number of Bifidobacteria and Lactobacillus spp. was not affected. In addition, Lf increased intestinal alkaline phosphatase activity (P<.05) and delayed the onset of food transitional diarrhea, reducing its frequency and duration (P<.05). The incidence of diarrhea in the high and low Lf groups was decreased 54% and 15%, respectively, compared with the control group (P=.035). In summary, these findings provide new evidence that dietary Lf supplementation up-regulated gene expression of BDNF and UCHL1, decreased the colon microbiota of E. coli, improved gut maturation and reduced early weaning diarrhea in piglets. The molecular basis underlying these findings suggests that Lf may enhance gut development and immune function by providing new insight into the gut-brain-microbe axis that has not been previously reported.