A de novo Variant in CROCC identified in a Chinese family implies the potential association with Atlanto-occipital Fusion (AOF)

Poster presentation for the Physoc 2021 annual conference. Atlanto-occipital fusion (AOF) is a rare skeletal malformation causing nerve compression with high risk of fatal. Its genetic information is currently lacking. Through whole-exome sequencing (WES) on a Chinese family having a sporadic proband son of AOF but other healthy family members, we identified a novel variant (chr1: c.4702C>T: p.R1568C) in ciliary rootlet coiled-coil (CROCC). The variant had different genotypes between the proband and healthy family members but with high conservations of “damage” to protein structure based on MutationTaster and SIFT forecast. CROCC gene can be obtained in both healthy (n=220) and non-mutated AOF patient samples (n=68) but absented in five sporadic patients with the novel variant. Furthermore, abnormal of cilia was observed after editing the target sequence on CROCC using CRISPR-Cas9. These results suggested that AOF might be caused by the mutation of the variant c.4702C>T:p.R1568C in CROCC. With strong amino acid conservation and interaction regulation, the variant mutation could cause the signal disorder of skeletal development which may lead to the defective bone formation and finally cause the development of AOF

Implication of a de novo Variant in ciliary rootlet coiledcoil (CROCC) with assimilation of atlas (AOA)

Assimilation of atlas is a rare skeletal malformation causing nerve compression with high risk of fatal. However, the genetic etiology of assimilation of atlas AOA is currently lacking. In this paper, the whole-exome sequencing (WES) analysis was employed to study a Chinese family having a sporadic proband son of assimilation of atlas AOA but other healthy family members. We identified a novel variant in ciliary rootlet coiled-coil gene (NM_014675.5 (CROCC): c.4702C>T (r.4702c>u, p.(Arg1568Cys)). The variant had different genotypes between the proband and healthy family members but with high conservations of “damage” to protein structure based on MutationTaster and SIFT prediction. CROCC gene can be obtained in both healthy (n=220) and non-mutated assimilation of atlas AOA patient samples (n=68) but absented in five sporadic patients with the novel variant. Furthermore, abnormal of cilia was observed after editing the target sequence on CROCC using CRISPR-Cas9. These results suggested that assimilation of atlas AOA might be caused by the mutation of CROCC: c.4702C>T (r.4702c>u, p.(Arg1568Cys)). With strong amino acid conservation and interaction regulation, the variant mutation could cause the signal disorder of skeletal development which may lead to the defective bone formation and finally cause the development of assimilation of atlas AOA

Differential responses to lithium in hyperexcitable neurons from patients with bipolar disorder.

Bipolar disorder is a complex neuropsychiatric disorder that is characterized by intermittent episodes of mania and depression; without treatment, 15% of patients commit suicide. Hence, it has been ranked by the World Health Organization as a top disorder of morbidity and lost productivity. Previous neuropathological studies have revealed a series of alterations in the brains of patients with bipolar disorder or animal models, such as reduced glial cell number in the prefrontal cortex of patients, upregulated activities of the protein kinase A and C pathways and changes in neurotransmission. However, the roles and causation of these changes in bipolar disorder have been too complex to exactly determine the pathology of the disease. Furthermore, although some patients show remarkable improvement with lithium treatment for yet unknown reasons, others are refractory to lithium treatment. Therefore, developing an accurate and powerful biological model for bipolar disorder has been a challenge. The introduction of induced pluripotent stem-cell (iPSC) technology has provided a new approach. Here we have developed an iPSC model for human bipolar disorder and investigated the cellular phenotypes of hippocampal dentate gyrus-like neurons derived from iPSCs of patients with bipolar disorder. Guided by RNA sequencing expression profiling, we have detected mitochondrial abnormalities in young neurons from patients with bipolar disorder by using mitochondrial assays; in addition, using both patch-clamp recording and somatic Ca2+ imaging, we have observed hyperactive action-potential firing. This hyperexcitability phenotype of young neurons in bipolar disorder was selectively reversed by lithium treatment only in neurons derived from patients who also responded to lithium treatment. Therefore, hyperexcitability is one early endophenotype of bipolar disorder, and our model of iPSCs in this disease might be useful in developing new therapies and drugs aimed at its clinical treatment

Identification of Potential Key lncRNAs in the Context of Mouse Myeloid Differentiation by Systematic Transcriptomics Analysis

Hematopoietic differentiation is a well-orchestrated process by many regulators such as transcription factor and long non-coding RNAs (lncRNAs). However, due to the large number of lncRNAs and the difficulty in determining their roles, the study of lncRNAs is a considerable challenge in hematopoietic differentiation. Here, through gene co-expression network analysis over RNA-seq data generated from representative types of mouse myeloid cells, we obtained a catalog of potential key lncRNAs in the context of mouse myeloid differentiation. Then, employing a widely used in vitro cell model, we screened a novel lncRNA, named Gdal1 (Granulocytic differentiation associated lncRNA 1), from this list and demonstrated that Gdal1 was required for granulocytic differentiation. Furthermore, knockdown of Cebpe, a principal transcription factor of granulocytic differentiation regulation, led to down-regulation of Gdal1, but not vice versa. In addition, expression of genes involved in myeloid differentiation and its regulation, such as Cebpa, were influenced in Gdal1 knockdown cells with differentiation blockage. We thus systematically identified myeloid differentiation associated lncRNAs and substantiated the identification by investigation of one of these lncRNAs on cellular phenotype and gene regulation levels. This study promotes our understanding of the regulation of myeloid differentiation and the characterization of roles of lncRNAs in hematopoietic system

Exosome and Exosomal MicroRNA: Trafficking, Sorting, and Function

Exosomes are 40–100 nm nano-sized vesicles that are released from many cell types into the extracellular space. Such vesicles are widely distributed in various body fluids. Recently, mRNAs and microRNAs (miRNAs) have been identified in exosomes, which can be taken up by neighboring or distant cells and subsequently modulate recipient cells. This suggests an active sorting mechanism of exosomal miRNAs, since the miRNA profiles of exosomes may differ from those of the parent cells. Exosomal miRNAs play an important role in disease progression, and can stimulate angiogenesis and facilitate metastasis in cancers. In this review, we will introduce the origin and the trafficking of exosomes between cells, display current research on the sorting mechanism of exosomal miRNAs, and briefly describe how exosomes and their miRNAs function in recipient cells. Finally, we will discuss the potential applications of these miRNA-containing vesicles in clinical settings

Synaptotagmin-7 is a key factor for bipolar-like behavioral abnormalities in mice

The pathogenesis of bipolar disorder (BD) has remained enigmatic, largely because genetic animal models based on identified susceptible genes have often failed to show core symptoms of spontaneous mood cycling. However, pedigree and induced pluripotent stem cell (iPSC)-based analyses have implicated that dysfunction in some key signaling cascades might be crucial for the disease pathogenesis in a subpopulation of BD patients. We hypothesized that the behavioral abnormalities of patients and the comorbid metabolic abnormalities might share some identical molecular mechanism. Hence, we investigated the expression of insulin/synapse dually functioning genes in neurons derived from the iPSCs of BD patients and the behavioral phenotype of mice with these genes silenced in the hippocampus. By these means, we identified synaptotagmin-7 (Syt7) as a candidate risk factor for behavioral abnormalities. We then investigated Syt7 knockout (KO) mice and observed nocturnal manic-like and diurnal depressive-like behavioral fluctuations in a majority of these animals, analogous to the mood cycling symptoms of BD. We treated the Syt7 KO mice with clinical BD drugs including olanzapine and lithium, and found that the drug treatments could efficiently regulate the behavioral abnormalities of the Syt7 KO mice. To further verify whether Syt7 deficits existed in BD patients, we investigated the plasma samples of 20 BD patients and found that the Syt7 mRNA level was significantly attenuated in the patient plasma compared to the healthy controls. We therefore concluded that Syt7 is likely a key factor for the bipolar-like behavioral abnormalities.</p