The role of Islet-1 in cell specification,differentiation,and maintenance of phenotypes in the vertebrate neural retina

Many blinding diseases,such as retinitis pigmentosa,age-related macular degeneration,and glaucoma involve the permanent loss of retinal neurons,especially photoreceptors or the centrally projecting retinal ganglion cells.Stem cells have been proposed as a potential source of cells for neuronal transplantation.

Dual regulatory role for phosphatase and tensin homolog in specification of intestinal endocrine cell subtypes

AIM:To investigate the impact of phosphatase and tensin homolog(Pten) in the specification of intestinal enteroendocrine subpopulations.METHODS:Using the Cre/loxP system,a mouse with conditional intestinal epithelial Pten deficiency was generated.Pten mutant mice and controls were sacrificed and small intestines collected for immunofluorescence and quantitative real-time polymerase chain reaction.Blood was collected on 16 h fasted mice by cardiac puncture.Enzyme-linked immunosorbent assay was used to measure blood circulating ghrelin,somatostatin(SST) and glucose-dependent insulinotropic peptide(GIP) levels.RESULTS:Results show an unexpected dual regulatory role for epithelial Pten signalling in the specification/differentiation of enteroendocrine cell subpopulations in the small intestine.Our data indicate that Pten positively regulates chromogranin A(CgA) expressing subpopulations,including cells expressing secretin,ghrelin,gastrin and cholecystokinin(CCK).In contrast,Pten negatively regulates the enteroendocrine subtype specification of non-expressing CgA cells such as GIP and SST expressing cells.CONCLUSION:The present results demonstrate that Pten signalling favours the enteroendocrine progenitor to specify into cells expressing CgA including those producing CCK,gastrin and ghrelin.

Enhancement of mouse germ cell-associated genes expression by injection of human umbilical cord mesenchymal stem cells into the testis of chemical-induced azoospermic mice

Various methods are currently under investigation to preserve fertility in males treated with high-dose chemotherapy and radiation for malignant and nonmalignant disorders. Human umbilical cord mesenchymal stem cells （HUC-MSCs）, which possess potent immunosuppressive function and secrete various cytokines and growth factors, have the potential clinical applications. As a potential alternative, we investigate whether injection of HUC-MSCs into the interstitial compartment of the testes to promote spermatogenic regeneration efficiently. HUC-MSCs were isolated from different sources of umbilical cords and injected into the interstitial space of one testis from 10 busulfan-treated mice （saline and HEK293 cells injections were performed in a separate set of mice） and the other testis remained uninjected. Three weeks after MSCs injection, Relative quantitative reverse transcription polymerase chain reaction was used to identify the expression of 10 of germ cell associated, which are all related to meiosis, demonstrated higher levels of spermatogenic gene expression （2-8 fold） in HUC-MSCs injected testes compared to the contralateral uninjected testes （five mice）. Protein levels for germ cell-specific genes, miwi, vasa and synaptonemal complex protein （Scp3） were also higher in MSC-treated testes compared to injected controls 3 weeks after treatment. However, no different expression was detected in saline water and HEK293 cells injection control group. We have demonstrated HUC-MSCs could affect mouse germ cell-specific genes expression. The results also provide a possibility that the transplanted HUC-MSCs may promote the recovery of spermatogenesis. This study provides further evidence for preclinical therapeutic effects of HUC-MSCs, and explores a new approach to the treatment of azoospermia.

Alpl prevents bone ageing sensitivity by specifically regulating senescence and differentiation in mesenchymal stem cells

Mutations in the liver/bone/kidney alkaline phosphatase(Alpl) gene cause hypophosphatasia(HPP) and early-onset bone dysplasia,suggesting that this gene is a key factor in human bone development. However, how and where Alpl acts in bone ageing is largely unknown. Here, we determined that ablation of Alpl induces prototypical premature bone ageing characteristics, including bone mass loss and marrow fat gain coupled with elevated expression of p16INK4A(p16) and p53 due to senescence and impaired differentiation in mesenchymal stem cells(MSCs). Mechanistically, Alpl deficiency in MSCs enhances ATP release and reduces ATP hydrolysis. Then, the excessive extracellular ATP is, in turn, internalized by MSCs and causes an elevation in the intracellular ATP level, which consequently inactivates the AMPKα pathway and contributes to the cell fate switch of MSCs. Reactivating AMPKα by metformin treatment successfully prevents premature bone ageing in Alpl+/-mice by improving the function of endogenous MSCs.These results identify a previously unknown role of Alpl in the regulation of ATP-mediated AMPKα alterations that maintain MSC stemness and prevent bone ageing and show that metformin offers a potential therapeutic option.

Cell Type Specific Expression of CD80 （B7-1） Gene in Murine

The CD80 （B7-1） costimulatory molecule is expressed on the surface of B cells and its expression is transcriptionally upregulated upon stimuli. To identify the region of murine CD80 promoter that direct cell type specific gene expression, four promoters construct of CD80 gene were generated with DNA fragments fused to the GFP reporter gene. In the present study, significant promoter activity was detected with all four promoter constructs only in the murine B lymphocyte. Further, the CD80 promoter region extending from -3,005 bp to ＋273 bp in relation to the previously reported transcription start site, was identified as tissue specific region. Interestingly, the shortest 700 bp （-427/＋273） of promoter fragment was sufficient to direct the CD80 gene expression. The level of CD80 expression was also found to be modulated by exogenous stimuli in B lymphocyte. Additionally, it was demonstrated that the CD80 gene expression is regulated at the level of transcription where the inducible CD80 gene transcript was detected in B lymphocyte with increasing time.

A novel method for identifying SARS-CoV-2 infection mutants via an epitope-specific CD8^(+)T cell test

Since the outbreak of the coronavirus disease 2019(COVID-19)epidemic in 2019,the public health system has faced enormous challenges.Tracking the individuals who test positive for severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)is a key step for interrupting chains of transmission of SARS-CoV-2 and reducing COVID-19-associated mortality.With the increasing of asymptomatic infections,it is difficult to track asymptomatic infections through epidemiological surveys and virus whole-genome sequencing.However,due to the cross-reactivity of neutralizing antibodies produced by multiple virus subtypes,neutralizing antibody detection cannot be used to determine whether an individual has a history of infection with a specific subtype of SARS-CoV-2.We recruited 4 human leukocyte antigen A2(HLA-A2)infections,15 individuals who received three doses of inactivated vaccines,and 30 breakthrough infections after vaccination and discussed a case-tracking approach to detect epitope-specific CD8^(+)T cells in the peripheral blood of close contacts,including accurate HLA typing based on ribonucleic acid(RNA)-sequencing and flow cytometry data and the comparison and characterization of SARS-CoV-2 HLA-A2 and HLA-A24 epitope-specific CD8^(+)T cells.From individuals who received three doses of inactivated vaccine,we observed that the CD8^(+)T cell specificity for ancestral epitopes was significantly higher than for mutated epitopes,and the fold change of CD8^(+)T cells corresponding to mutated epitopes relative to ancestral epitopes was less than 1.The enzyme-linked immunospot(ELISpot)results further validate this result.This study forms a“method for understanding the infection history of SARS-CoV-2 subtypes based on the proportion of epitope-specific CD8^(+)T cells in the peripheral blood of subjects”,covering up to 46%of the population,including HLA-A2+and HLA-A24+donors,providing a novel method for SARS-CoV-2 infected case tracing.

MicroRNA expression profiles and functions in the brain

MicroRNAs are abundant in the brains of vertebrates and some show a brain-specific or brain-enriched expression pattern. Because microRNAs regulate the expression of hundreds of target genes, it is not surprising that they have profoundly important functions in brain development and pathological processes. For example, miR-124 plays an important role in inducing and maintaining neuronal identity through targeting at least two anti-neural factors. MicroRNAs have also been implicated in brain disorders, including brain tumors and neurodegenerative diseases. This review aims to present an overview of the expression profiles and functions of microRNAs in the developing brains of vertebrates.

Skin cell-derived extracellular vesicles:a promising therapeutic strategy for cutaneous injury

Wound healing refers to the healing process that occurs after the skin and other tissues are separated or damaged by internal or external forces.It is a complex combination of tissue regeneration,granulation tissue hyperplasia,and scar formation,and shows the synergistic effects of these processes.After skin damage,the environment around the wound and the cells at site of the damage respond immediately,and a range of cytokines and growth factors are released.In cutaneous injury,extracellular vesicle(EV)signaling plays a vital role in the healing process via paracrine and endocrine mechanisms.EVs are natural intercellular and inter-organ communication tools that carry various bioactive substances for message exchange.Stem cells and stem cell EVs facilitate tissue repair,showing promising potential in regenerative medicine.Nevertheless,EVs derived from specific skin tissue cells,such as epidermal cells,fibroblasts,vascular endothelial cells and inflammatory cells,also play important roles in cutaneous tissue repair.Here,we describe the characteristics of wound healing,concentrating on the production and functions of EVs derived from specific skin cells,and provide new ideas for wound therapy using EVs.

Cell type specificity of signaling:view from membrane receptors distribution and their downstream transduction networks

Studies on cell signaling pay more attention to spatial dynamics and how such diverse organization can relate to high order of cellular capabilities.To overview the specificity of cell signaling,we integrated human receptome data with proteome spatial expression profiles to systematically investigate the specificity of receptors and receptor-triggered transduction networks across 62 normal cell types and 14 cancer types.Six percent receptors showed cell-type-specific expression,and 4% signaling networks presented enriched cell-specific proteins induced by the receptors.We introduced a concept of“response context”to annotate the cell-type dependent signaling networks.We found that most cells respond similarly to the same stimulus,as the“response contexts”presented high functional similarity.Despite this,the subtle spatial diversity can be observed from the difference in network architectures.The architecture of the signaling networks in nerve cells displayed less completeness than that in glandular cells,which indicated cellular-context dependent signaling patterns are elaborately spatially organized.Likewise,in cancer cells most signaling networks were generally dysfunctional and less complete than that in normal cells.However,glioma emerged hyper-activated transduction mechanism in malignant state.Receptor ATP6AP2 and TNFRSF21 induced rennin-angiotensin and apoptosis signaling were found likely to explain the glioma-specific mechanism.This work represents an effort to decipher context-specific signaling network from spatial dimension.Our results indicated that although a majority of cells engage general signaling response with subtle differences,the spatial dynamics of cell signaling can not only deepen our insights into different signaling mechanisms,but also help understand cell signaling in disease.

Techniques of cell type-specific transcriptome analysis and applications in researches of sexual plant reproduction

In higher plants, specific cell differentiation and fate decision are controlled by differential gene expression.Cell type-specific transcriptome analysis has become an important tool for investigating cell regulatory mechanisms. Inrecent years, many different techniques have been developed for the isolation of specific cells and the subsequenttranscriptome analysis, and considerable data are available regarding the transcriptional profiles of some specific cells.These cell type-specific transcriptome analyses hold significant promise for elucidating the gene expression linked tocellular identities and functions, and are extraordinarily important for research in functional genomics and systemsbiology aimed toward basic understanding of molecular networks and pathway interactions. Moreover, to reveal thecritical mechanisms about sexual plant reproduction, the gamete and embryo cells have long been treated as goodsubjects for cell-specific transcriptome analysis, and there has been important progress in recent decades. In this review,we summarize current technologies in cell type-specific transcriptome analysis and review the applications of thesetechnologies in research into the mechanisms of sexual reproduction in higher plants.

m^(6)A reader Igf2bp3 enables germ plasm assembly by mA-dependent regulation of gene expression in zebrafish

Bucky ball(Buc)is involved in germ plasm(GP)assembly during early zebrafish development by regulating GP mRNA expression via an unknown mechanism.The present study demonstrates that an m^(6)A reader Igf2bp3 interacts and colocalizes with Buc in the GP.Similar to the loss of Buc,the genetic deletion of maternal igf2bp3 in zebrafish leads to abnormal GP assembly and insufficient germ cell specification,which can be partially restored by the injection of igf2 bp3 mRNA.Igf2bp3 binds to m^(6)A-modified GPorganizer and GP mRNAs in an m^(6)A-dependent manner and prevents their degradation.These findings indicate that the functions of Igf2bp3,a direct effector protein of Buc,in GP mRNA expression and GP assembly involve m^(6)A-dependent regulation;these results emphasize a critical role of m^(6)A modification in the process of GP assembly.

MODELING AND PARAMETER IDENTIFICATION FOR MULTISTAGE SIMULATION OF MICROBIAL BIOCONVERSION IN BATCH CULTURE

The bioconversion of glycerol to 1,3-propanediol is a complex bioprocess. The item of product inhibition in the equation of Specific rate of cell growth is overlapped in [L. Wang, J. X. Ye, E. M. Feng and Z. L. Xiu, An improved model for multistage simula- tion of glycerol fermentation in batch culture and its parameter identification, Nonlinear Anal. Hybrid Syst. 3（4） （2009） 455462]. Therefore, in this work, the specific rate of cell growth is modified by the mechanism of multistage simulation of microbial bioconversion and the previous time-dependent model is converted to the autonomous standard form. The properties of the solutions for the nonlinear dynamic system are discussed and the identifiability of the parameters is proved. Finally the feasible optimization algorithm is constructed to find the optimal parameters for the system. Numerical result shows that the improved model with identified parameters can describe the batch culture better, compared with the previous results.