NRG1 Regulates Proliferation, Migration and Differentiation of Human Limbal Epithelial Stem Cells.

Limbal epithelial stem/progenitor cells (LESCs) proliferate, migrate and differentiate into mature corneal epithelium cells (CECs) that cover the ocular surface. LESCs play a crucial role in the maintenance and regeneration of the corneal epithelium, and their dysfunction can lead to various corneal diseases. Neuregulin 1 (NRG1) is a member of the epidermal growth factor family that regulates the growth and differentiation of epithelial tissues. Here, we depicted the dynamic transcriptomic profiles during human CEC differentiation, identifying six gene co-expression modules that were specific to different differentiation stages. We found that the expression of NRG1 was high in human LESCs and decreased dramatically upon differentiation. Knockdown of NRG1 significantly inhibited LESC proliferation and upregulated the expression of the terminal differentiation marker genes KRT3, KRT12 and CLU. In addition, the scratch wound closure assay showed that knockdown of NRG1 attenuated wound closure of LESCs over 24 h. Together, we dissected the transcriptional regulatory dynamics during CEC differentiation and identified NRG1 as a key regulator that promoted LESC proliferation and migration and maintained the undifferentiated state.

Paraburkholderia dinghuensis sp. nov., isolated from soil.

A novel Gram-stain-negative, aerobic, non-spore-forming, non-motile and rod-shaped bacterial strain, designated DHOA04T, was isolated from a forest soil sample collected at Dinghushan Biosphere Reserve, Guangdong Province, PR China (112° 31' E 23° 10' N). It grew optimally at 28-33 °C and pH 6.5-7.0. Strain DHOA04T contained Q-8 as the major respiratory quinone. Its main fatty acids were C16 : 0, C17 : 0cyclo, summed feature 3 (C16 : 1ω6c and/or C16 : 1ω7c) and summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c). The DNA G+C content of DHOA04T was 63.0 mol%, which is in the range of the genus Paraburkholderia. The average nucleotide identity and digital DNA-DNA hybridization values for the complete genomes were 81.6-83.0 and 25.5-27.0 % between strain DHOA04T and five closely related type strains. The major polar lipids were phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol and two unidentified aminophospholipids. On the basis of 16S rRNA gene sequence analysis, the strain was found to be closely related to members of the genus Paraburkholderia, but clearly separated from the established species. Phylogenetic analysis based on the 16S rRNA gene sequences using the maximum-likelihood algorithm indicated that strain DHOA04T was most closely related to Paraburkholderia ferrariae NBRC 106233T. The phenotypic, chemotaxonomic and phylogenetic data, and genome analysis showed that strain DHOA04T represents a novel species of the genus Paraburkholderia, for which the name Paraburkholderia dinghuensis sp. nov. is proposed. The type strain is DHOA04T (=KCTC 42627T=LMG 28839T).

The single-cell transcriptomic atlas and RORA-mediated 3D epigenomic remodeling in driving corneal epithelial differentiation.

Proper differentiation of corneal epithelial cells (CECs) from limbal stem/progenitor cells (LSCs) is required for maintenance of ocular homeostasis and clear vision. Here, using a single-cell transcriptomic atlas, we delineate the comprehensive and refined molecular regulatory dynamics during human CEC development and differentiation. We find that RORA is a CEC-specific molecular switch that initiates and drives LSCs to differentiate into mature CECs by activating PITX1. RORA dictates CEC differentiation by establishing CEC-specific enhancers and chromatin interactions between CEC gene promoters and distal regulatory elements. Conversely, RORA silences LSC-specific promoters and disrupts promoter-anchored chromatin loops to turn off LSC genes. Collectively, our work provides detailed and comprehensive insights into the transcriptional dynamics and RORA-mediated epigenetic remodeling underlying human corneal epithelial differentiation.

Chemical Vapor Transport Synthesis of Fibrous Red Phosphorus Crystal as Anodes for Lithium-Ion Batteries.

Red phosphorus (RP) is considered to be the most promising anode material for lithium-Ion batteries (LIBs) due to its high theoretical specific capacity and suitable voltage platform. However, its poor electrical conductivity (10-12 S/m) and the large volume changes that accompany the cycling process severely limit its practical application. Herein, we have prepared fibrous red phosphorus (FP) that possesses better electrical conductivity (10-4 S/m) and a special structure by chemical vapor transport (CVT) to improve electrochemical performance as an anode material for LIBs. Compounding it with graphite (C) by a simple ball milling method, the composite material (FP-C) shows a high reversible specific capacity of 1621 mAh/g, excellent high-rate performance and long cycle life with a capacity of 742.4 mAh/g after 700 cycles at a high current density of 2 A/g, and coulombic efficiencies reaching almost 100% for each cycle.

ETS1-HMGA2 Axis Promotes Human Limbal Epithelial Stem Cell Proliferation.

Purpose: This study aimed to investigate the role and molecular mechanism of ETS1 in the proliferation and differentiation of human limbal epithelial stem cells (LESCs). Methods: RNA-seq and quantitative real-time PCR were used to determine gene expression changes when ETS1 and HMGA2 was knocked down using short-hairpin RNAs or overexpressed by lentivirus. Immunofluorescence and flow cytometry experiments were performed to assess the roles of ETS1 and HMGA2 in LESC proliferation. ETS1-bound cis-regulatory elements and target genes in LESCs were identified using chromatin immunoprecipitation sequencing. The epigenetic features of ETS1-binding sites were assessed by the published histone modification and chromatin accessibility profiles. Results: ETS1 was robustly expressed in LESCs but dramatically reduced on differentiation into corneal epithelial cells (CECs). ETS1 knockdown in LESCs inhibited cellular proliferation and activated CEC markers (KRT3, KRT12, CLU, and ALDH3A1). When ETS1 was overexpressed during CEC differentiation, LESC-associated genes were upregulated while CEC-associated genes were downregulated. The genome-wide binding profile of ETS1 was identified in LESCs. ETS1 occupied H3K4me3-marked promoters and H3K27ac/H3K4me1-marked enhancers. ETS1-binding sites were also enriched for chromatin accessibility signal. HMGA2 showed a consistent expression pattern with ETS1. ETS1 activates HMAG2 by binding to its promoter. Knockdown and overexpression experiments suggested that HMGA2 can promote LESC proliferation and inhibits its differentiation. Conclusions: ETS1 promotes LESC proliferation and inhibits its differentiation via activating HMGA2.

Cis-regulatory chromatin loops analysis identifies GRHL3 as a master regulator of surface epithelium commitment.

Understanding the regulatory network of cell fate acquisition remains a major challenge. Using the induction of surface epithelium (SE) from human embryonic stem cells as a paradigm, we show that the dynamic changes in morphology-related genes (MRGs) closely correspond to SE fate transitions. The marked remodeling of cytoskeleton indicates the initiation of SE differentiation. By integrating promoter interactions, epigenomic features, and transcriptome, we delineate an SE-specific cis-regulatory network and identify grainyhead-like 3 (GRHL3) as an initiation factor sufficient to drive SE commitment. Mechanically, GRHL3 primes the SE chromatin accessibility landscape and activates SE-initiating gene expression. In addition, the evaluation of GRHL3-mediated promoter interactions unveils a positive feedback loop of GRHL3 and bone morphogenetic protein 4 on SE fate decisions. Our work proposes a concept that MRGs could be used to identify cell fate transitions and provides insights into regulatory principles of SE lineage development and stem cell-based regenerative medicine.

Comprehensive 3D epigenomic maps define limbal stem/progenitor cell function and identity.

The insights into how genome topology couples with epigenetic states to govern the function and identity of the corneal epithelium are poorly understood. Here, we generate a high-resolution Hi-C interaction map of human limbal stem/progenitor cells (LSCs) and show that chromatin multi-hierarchical organisation is coupled to gene expression. By integrating Hi-C, epigenome and transcriptome data, we characterize the comprehensive 3D epigenomic landscapes of LSCs. We find that super-silencers mediate gene repression associated with corneal development, differentiation and disease via chromatin looping and/or proximity. Super-enhancer (SE) interaction analysis identified a set of SE interactive hubs that contribute to LSC-specific gene activation. These active and inactive element-anchored loop networks occur within the cohesin-occupied CTCF-CTCF loops. We further reveal a coordinated regulatory network of core transcription factors based on SE-promoter interactions. Our results provide detailed insights into the genome organization principle for epigenetic regulation of gene expression in stratified epithelia.

[Case control study of different fixing methods for intertrochanteric fractures].

OBJECTIVE: To compare the clinical effects of different fixing methods for intertrochanteric fractures and make theoretical analysis. METHODS: From June 2003 to June 2007, 321 patients with intertrochanteric fractures, male 132 and female 189, ranging in age from 20 to 93 years with an average of 56.8 years, were treated with different fixation including Richard nail (142 cases), proximal femora nail (PFN, 94 cases) and external fixator (85 cases). The clinical data of all the patients were retrospectively analyzed, including the incidence of complications, joint function of hip (according Kudema modified Merli D'Aubigne criteria). RESULTS: All patients were followed up from 10 months to 4 years with an average of 14 months. About the incidence of complications, there was significant difference between the external fixator group and the others two groups (P < 0.05); there was no significant difference between the Richard nail group and the PFN group (P > 0.05). There was significant difference in joint function of hip among three methods. PEN group was best than others two groups. CONCLUSION: There is the best clinical effects and lowest incidence of complications with PFN method, which is the better choice in treating intertrochanteric fractures.