Biology subjects

An, K.

Publications and source records attributed to An, K..

23 records · Page 2Linked to original sources

bioRxiv2022

Integrative single-cell characterization of hypothalamus sex-differential and obesity-associated genes and regulatory elements

Over 500 noncoding genomic loci are associated with obesity. The majority of these loci reside near genes that are expressed in the hypothalamus in specific neuronal subpopulations that regulate food intake, hindering the ability to identify and functionally characterize them. Here, we carried out integrative single-cell analysis (RNA/ATAC-seq) on both mouse and human male and female hypothalamus to characterize genes and regulatory elements in specific cell subpopulations. Utilizing both transcriptome and regulome data, we identify over 30 different neuronal and non-neuronal cell subpopulations and a shared core of transcription factors that regulate cell cluster-specific genes between mice and humans. We characterize several sex-specific differentially expressed genes and the regulatory elements that control them in specific cell subpopulations. Overlapping cell-specific scATAC peaks with obesity-associated GWAS variants, identifies potential obesity-associated regulatory elements. Using reporter assays and CRISPR editing, we show that many of these sequences, including the top obesity-associated loci (FTO and MC4R), are functional enhancers whose activity is altered due to the obesity-associated variant and regulate known obesity genes. Combined, our work provides a catalog of genes and regulatory elements in hypothalamus cell subpopulations and uses obesity to showcase how integrative single-cell sequencing can identify functional variants associated with hypothalamus-related phenotypes.

neuroscience↗

bioRxiv2022

ADGRG6 promotes adipogenesis and is involved in sex-specific fat distribution

Fat distribution differences between males and females are a major risk factor for metabolic disease, but their genetic etiology remains largely unknown. Here, we establish ADGRG6 as a major factor in adipogenesis and gender fat distribution. Deletion of ADGRG6 in human adipocytes impairs adipogenesis due to reduced cAMP signaling. Conditionally knocking out Adgrg6 in mouse adipocytes or deleting an intronic enhancer associated with gender fat distribution generates males with female-like fat deposition, which are protected against high-fat-diet-induced obesity and have improved insulin response. To showcase its therapeutic potential, we demonstrate that CRISPRi targeting of the Adgrg6 promoter or enhancer prevents high-fat-diet-induced obesity. Combined, our results associate ADGRG6 as a gender fat distribution gene and highlight its potential as a therapeutic target for metabolic disease.

genomics↗

bioRxiv2022

NSUN2-mediated mRNA m5C Modification Regulates the Progression of Hepatocellular Carcinoma

RNA modification affects many biological processes and physiological diseases. The 5-methylcytosine (m5C) modification regulates the progression of multiple tumors. However, its characteristics and functions in hepatocellular carcinoma (HCC) remain largely unknown. Here, we found that HCC tissues had a higher m5C methylation level than the adjacent normal tissues. Transcriptome analysis revealed that a major fraction of the hypermethylated genes participated in the phosphokinase signaling pathways, such as the Ras and PI3K-Akt pathways. The m5C methyltransferase NSUN2 was highly expressed in HCC tissues consistently. Interestingly, the expression of many oncogenes was positively correlated with the expression of NSUN2, including GRB2, RNF115, AATF, ADAM15, RTN3, and HDGF. Real-time PCR assays further revealed that the expression of the mRNA of GRB2, RNF115, and AATF decreased significantly with the depletion of NSUN2 in HCC cells. Furthermore, NSUN2 could regulate the cellular sensitivity of HCC cells to sorafenib via modulating the Ras signaling pathway. Moreover, knocking down NSUN2 caused cell cycle arrest. Our study demonstrated a vital role of NSUN2 in the progression of HCC.

cancer biology↗

bioRxiv2021

Prenatal immune stress induces a prolonged blunting of microglia activation that impacts striatal connectivity

Recent studies suggested that microglia, the primary brain immune cells, can affect circuit connectivity and neuronal function1-3. Microglia infiltrate the neuroepithelium early in embryonic development and are maintained in the brain throughout adulthood4,5. Several maternal environmental factors, such as aberrant microbiome, immune activation, and poor nutrition, can influence prenatal brain development6-8. Nevertheless, it is unknown how changes in the prenatal environment instruct the developmental trajectory of infiltrating microglia, which in turn affect brain development and function. Here we show that after maternal immune activation (MIA) microglia from the offspring have a long-lived decrease in immune reactivity (blunting) across the developmental trajectory. The blunted immune response was concomitant with changes in the chromatin accessibility and reduced transcription factor occupancy of the open chromatin. Single cell RNA sequencing revealed that MIA does not induce a distinct subpopulation but rather decreases the contribution to inflammatory microglia states. Prenatal replacement of MIA microglia with physiological infiltration of naive microglia ameliorated the immune blunting and restored a decrease in presynaptic vesicle release probability onto dopamine receptor type-two medium spiny neurons, indicating that aberrantly formed microglia due to an adverse prenatal environment impacts the long-term microglia reactivity and proper striatal circuit development.

neuroscience↗

bioRxiv2021

Anterior insula-associated social novelty recognition: orchestrated regulation by a local retinoic acid cascade and oxytocin signaling

BackgroundDeficits in social cognition consistently underlie functional disabilities in a wide range of psychiatric disorders. Neuroimaging studies have suggested that the anterior insula is a common core brain region that is impaired across neurological and psychiatric disorders, which include social cognition deficits. Nevertheless, neurobiological mechanisms of the anterior insula for social cognition remain elusive. MethodsTo determine the role of anterior insula in social cognition, we manipulated expression of Cyp26B1, an anterior insula-enriched molecule that is crucial for retinoic acid degradation and involved in the pathology of neuropsychiatric conditions. Social cognition was mainly assayed using the three-chamber social interaction test. We conducted multimodal analyses at the molecular, cellular, circuitry, and behavioral levels. ResultsAt the molecular/cellular level, anterior insula-mediated social novelty recognition is maintained by proper activity of the layer 5 pyramidal neurons, for which retinoic acid-mediated gene transcription can play a role. We also demonstrate that oxytocin influences the anterior insula-mediated social novelty recognition, not by direct projection of oxytocin neurons, nor by direct diffusion of oxytocin to the anterior insula, which contrasts the modes of oxytocin regulation onto the posterior insula. Instead, oxytocin affects oxytocin receptor-expressing neurons in the dorsal raphe nucleus where serotonergic neurons are projected to the anterior insula. Furthermore, we show that serotonin 5HT2C receptor expressed in the anterior insula influences social novelty recognition. ConclusionsAnterior insula plays a pivotal role in social novelty recognition that is partly regulated by a local retinoic acid cascade, but also remotely regulated by oxytocin via a non-classic mechanism.

animal behavior and cognition↗