Establishment of human cerebral organoid systems to model early neural development and assess the central neurotoxicity of environmental toxins

Human brain development is a complex process,and animal models often have significant limitations.To address this,researchers have developed pluripotent stem cell-derived three-dimensional structures,known as brain-like organoids,to more accurately model early human brain development and disease.To enable more consistent and intuitive reproduction of early brain development,in this study,we incorporated forebrain organoid culture technology into the traditional unguided method of brain organoid culture.This involved embedding organoids in matrigel for only 7 days during the rapid expansion phase of the neural epithelium and then removing them from the matrigel for further cultivation,resulting in a new type of human brain organoid system.This cerebral organoid system replicated the temporospatial characteristics of early human brain development,including neuroepithelium derivation,neural progenitor cell production and maintenance,neuron differentiation and migration,and cortical layer patterning and formation,providing more consistent and reproducible organoids for developmental modeling and toxicology testing.As a proof of concept,we applied the heavy metal cadmium to this newly improved organoid system to test whether it could be used to evaluate the neurotoxicity of environmental toxins.Brain organoids exposed to cadmium for 7 or 14 days manifested severe damage and abnormalities in their neurodevelopmental patterns,including bursts of cortical cell death and premature differentiation.Cadmium exposure caused progressive depletion of neural progenitor cells and loss of organoid integrity,accompanied by compensatory cell proliferation at ectopic locations.The convenience,flexibility,and controllability of this newly developed organoid platform make it a powerful and affordable alternative to animal models for use in neurodevelopmental,neurological,and neurotoxicological studies.

Functional role of circRNA CHRC through miR-431-5p/KLF15 signaling axis in the progression of heart failure

Pathological myocardial hypertrophy is a common early clinical manifestation of heart failure,with noncoding RNAs exerting regulatory influence.However,the molecular function of circular RNAs(circRNAs)in the progression from cardiac hypertrophy to heart failure remains unclear.To uncover functional circRNAs and identify the core circRNA signaling pathway in heart failure,we construct a global triple network(microRNA,circRNA,and mRNA)based on the competitive endogenous RNA(ceRNA)theory.We observe that cardiac hypertrophy-related circRNA(circRNA CHRC),within the ceRNA network,is down-regulated in both transverse aortic constriction mice and Ang-II--treated primary mouse cardiomyocytes.Silencing circRNA CHRC increases cross-sectional cell area,atrial natriuretic peptide,andβ-myosin heavy chain levels in primary mouse cardiomyocytes.Further screening shows that circRNA CHRC targets the miR-431-5p/KLF15 axis implicated in heart failure progression in vivo and in vitro.Immunoprecipitation with anti-Ago2-RNA confirms the interaction between circRNA CHRC and miR-431-5p,while miR-431-5p mimics reverse Klf15 activation caused by circRNA CHRC overexpression.In summary,circRNA CHRC attenuates cardiac hypertrophy via sponging miR-431-5p to maintain the normal level of Klf15 expression.

The silencing transcription factor REST targets UCHL1 to regulate inflammatory response and fibrosis during cardiac hypertrophy

RE1 silencing transcription factor(REST)plays a key role in embryonic development and fetal cardiac gene reactivation.1 However,understanding of the role of REST in cardiac remodeling is very limited.A recent study has shown that cardiac-specific REST knockout increases Gao expression,and impairs Ca^(2+)processing in ventricular 1 myocytes,leading to cardiac dysfunction.

Sinoatrial node pacemaker cells share dominant biological properties with glutamatergic neurons

Activation of the heart normally begins in the sinoatrial node(SAN).Electrical impulses spontaneously released by SAN pacemaker cells(SANPCs)trigger the contraction of the heart.However,the cellular nature of SANPCs remains controversial.Here,we report that SANPCs exhibit glutamatergic neuron-like properties.By comparing the single-cell transcriptome of SANPCs with that of cells from primary visual cortex in mouse,we found that SANPCs co-clustered with cortical neurons.Tissue and cellular imaging confirmed that SANPCs contained key elements of glutamatergic neurotransmitter system,expressing genes encoding glutamate synthesis pathway(G/s),ionotropic and metabotropic glutamate receptors(Grina,Gria3,Grm1 and Grm5)t and glutamate transporters(Slc17a7).SANPCs highly expressed cell markers of glutamatergic neurons(Snap25 and S/-c17a7)t whereas Gad1,a marker of GABAergic neurons,was negative.Functional studies revealed that inhibition of glutamate receptors or transporters reduced spontaneous pacing frequency of isolated SAN tissues and spontaneous Ca2+transients frequency in single SANPC.Collectively,our work suggests that SANPCs share dominant biological properties with glutamatergic neurons,and the glutamatergic neurotransmitter system may act as an intrinsic regulation module of heart rhythm,which provides a potential intervention target for pacemaker cell-associated arrhythmias.

Nucleoporin 35 regulates cardiomyocyte pH homeostasis by controlling Na^(+)-H^(+)exchanger-1 expression

The mammalian nuclear pore complex is comprised of∼30 different nucleoporins(Nups).It governs the nuclear import of gene expression modulators and the export of mRNAs.In cardiomyocytes,Na1-H1 exchanger-1(NHE1)is an integral membrane protein that exclusively regulates intracellular pH(pHi)by exchanging one intracellular H1 for one extracellular Na1.However,the role of Nups in cardiac NHE1 expression remains unknown.We herein report that Nup35 regulates cardiomyocyte NHE1 expression by controlling the nucleo-cytoplasmic trafficking of nhe1 mRNA.The N-terminal domain of Nup35 determines nhe1 mRNA nuclear export by targeting the 5′-UTR(2412 to2213 nt)of nhe1mRNA.Nup35 ablationweakensthe resistance of cardiomyocytes to an acid challenge by depressingNHE1 expression.Moreover,we identify thatNup35 andNHE1 are simultaneously downregulated in ischemic cardiomyocytes both in vivo and in vitro.Enforced expression of Nup35 effectively counteracts the anoxia-induced intracellular acidification.We conclude that Nup35 selectively regulates cardiomyocyte pHi homeostasis by posttranscriptionally controlling NHE1 expression.This finding reveals a novel regulatory mechanism of cardiomyocyte pHi,and may provide insight into the therapeutic strategy for ischemic cardiac diseases.