Human Breast Milk Exosomal miRNAs are Influenced by Premature Delivery and Affect Neurodevelopment.

SCOPE: This study investigates the exosomal microRNA (miRNA) profiles of term and preterm breast milk, including the most abundant and differentially expressed (DE) miRNAs, and their impact on neurodevelopment in infants. METHODS AND RESULTS: Mature milk is collected from the mothers of term and preterm infants. Using high-throughput sequencing and subsequent data analysis, exosomal miRNA profiles of term and preterm human breast milk (HBM) are acquired and it is found that the let-7 and miR-148 families are the most abundant miRNAs. Additionally, 23 upregulated and 15 downregulated miRNAs are identified. MiR-3168 is the most upregulated miRNA in preterm HBM exosome, exhibiting targeting activity toward multiple genes involved in the SMAD and MAPK signaling pathways and playing a crucial role in early neurodevelopment. Additionally, the effects of miR-3168 on neurodevelopment is confirmed and it is determined that it is an essential factor in the differentiation of neural stem cells (NSCs). CONCLUSION: This study demonstrates that miRNA expression in breast milk exosomes can be influenced by preterm delivery, thereby potentially impacting neurodevelopment in preterm infants.

Generation of a human iPSC line from a Parkinson's disease patient with a novel CHCHD2 mutation (p.R145Q).

Mutations in CHCHD2 have been reported to be associated with familial Parkinson's disease (PD). We generated a human induced pluripotent stem cell (hiPSC) line by reprogramming dermal fibroblasts from a PD patient harboring a novel CHCHD2 mutation (c.434G > A, p.R145Q). This line exhibited human embryonic stem cell (hESC)-like clonal morphology, expression of undifferentiated stem cell markers, a normal karyotype and trilineage differentiation capacity and thus the potential to serve as a model for further investigating the underlying molecular mechanisms of CHCHD2 function in PD.

Panning for gold: Purifying mesencephalic dopaminergic progenitors differentiated from human pluripotent stem cells.

In a recently published study, Xu et al. used two surface markers, CLSTN2 and PTPRO, to generate highly purified donor dopaminergic neurons and achieved stable and predictable therapeutic outcomes by transplantation into the brain of PD animal models (Xu et al., 2022).

Generation of an induced pluripotent stem cell line from a patient with global development delay carrying DYRK1A mutation (c.1730T>A) and a gene correction isogenic iPSC line.

Mental retardation autosomal dominant 7 (MRD7), or DYRK1A Related Intellectual Disability Syndrome (OMIM 614104) is a developmental syndrome with microcephaly, intellectual disability, language delay and epileptic seizures. Haploinsufficiency of DYRK1A is the cause of MRD7. Here, we generated an induced pluripotent stem cell (iPSC) line with the mutation (DYRK1Ac.1730T>A) from the Peripheral blood mononuclear cell (PBMC) of a MRD7 patient along with an isogenic gene-corrected control iPSC line by CRISPR/Cas9 genome editing. Both iPSC lines showed full pluripotency, normal karyotype and differentiation capacity without integrating vectors. These DYRK1A mutant and isogenic gene-corrected iPSC control line provides a useful model to study the underlying molecular mechanisms of MRD7.

Transcriptional networks identify synaptotagmin-like 3 as a regulator of cortical neuronal migration during early neurodevelopment.

Human brain development is a complex process involving neural proliferation, differentiation, and migration that are directed by many essential cellular factors and drivers. Here, using the NetBID2 algorithm and developing human brain RNA sequencing dataset, we identify synaptotagmin-like 3 (SYTL3) as one of the top drivers of early human brain development. Interestingly, SYTL3 exhibits high activity but low expression in both early developmental human cortex and human embryonic stem cell (hESC)-derived neurons. Knockout of SYTL3 (SYTL3-KO) in human neurons or knockdown of Sytl3 in embryonic mouse cortex markedly promotes neuronal migration. SYTL3-KO causes an abnormal distribution of deep-layer neurons in brain organoids and reduces presynaptic neurotransmitter release in hESC-derived neurons. We further demonstrate that SYTL3-KO-accelerated neuronal migration is modulated by high expression of matrix metalloproteinases. Together, based on bioinformatics and biological experiments, we identify SYTL3 as a regulator of cortical neuronal migration in human and mouse developing brains.

Generation of an induced pluripotent stem cell line from an Alström Syndrome patient with ALMS1 mutation (c.3902C > A, c.6436C > T) and a gene correction isogenic iPSC line.

To develop a disease model for the human Alström Syndrome (AS), we used the episomal reprogramming system and CRISPR/Cas9 technology to generate an induced pluripotent stem cell (iPSC) line with the compound heterozygous patient mutation (ALMS1 c.3902C > A, c.6436C > T) along with an isogenic gene-corrected control iPSC line. Both iPSC lines showed normal karyotype, expressed pluripotent markers, and differentiated into cells of three embryonic germ layer. These AS mutant and isogenic iPSC control line will be of great use in investigating the disease mechanisms, drug screening and treatment in patients.

UTX Regulates Human Neural Differentiation and Dendritic Morphology by Resolving Bivalent Promoters.

UTX, a H3K27me3 demethylase, plays an important role in mouse brain development. However, so little is known about the function of UTX in human neural differentiation and dendritic morphology. In this study, we generated UTX-null human embryonic stem cells using CRISPR/Cas9, and differentiated them into neural progenitor cells and neurons to investigate the effects of UTX loss of function on human neural development. The results showed that the number of differentiated neurons significantly reduced after loss of UTX, and that the dendritic morphology of UTX KO neurons tended to be simplified. The electrophysiological recordings showed that most of the UTX KO neurons were immature. Finally, RNA sequencing identified dozens of differentially expressed genes involved in neural differentiation and synaptic function in UTX KO neurons and our results demonstrated that UTX regulated these critical genes by resolving bivalent promoters. In summary, we establish a reference for the important role of UTX in human neural differentiation and dendritic morphology.

The Histone H3K27 Demethylase UTX Regulates Synaptic Plasticity and Cognitive Behaviors in Mice.

Histone demethylase UTX mediates removal of repressive trimethylation of histone H3 lysine 27 (H3K27me3) to establish a mechanistic switch to activate large sets of genes. Mutation of Utx has recently been shown to be associated with Kabuki syndrome, a rare congenital anomaly syndrome with dementia. However, its biological function in the brain is largely unknown. Here, we observe that deletion of Utx results in increased anxiety-like behaviors and impaired spatial learning and memory in mice. Loss of Utx in the hippocampus leads to reduced long-term potentiation and amplitude of miniature excitatory postsynaptic current, aberrant dendrite development and defective synapse formation. Transcriptional profiling reveals that Utx regulates a subset of genes that are involved in the regulation of dendritic morphology, synaptic transmission, and cognition. Specifically, Utx deletion disrupts expression of neurotransmitter 5-hydroxytryptamine receptor 5B (Htr5b). Restoration of Htr5b expression in newborn hippocampal neurons rescues the defects of neuronal morphology by Utx ablation. Therefore, we provide evidence that Utx plays a critical role in modulating synaptic transmission and cognitive behaviors. Utx cKO mouse models like ours provide a valuable means to study the underlying mechanisms of the etiology of Kabuki syndrome.