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Swamynathan SK, Swamynathan S. Corneal epithelial development and homeostasis. Differentiation 2023; 132:4-14. [PMID: 36870804 PMCID: PMC10363238 DOI: 10.1016/j.diff.2023.02.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Revised: 01/27/2023] [Accepted: 02/20/2023] [Indexed: 03/06/2023]
Abstract
The corneal epithelium (CE), the most anterior cellular structure of the eye, is a self-renewing stratified squamous tissue that protects the rest of the eye from external elements. Each cell in this exquisite three-dimensional structure needs to have proper polarity and positional awareness for the CE to serve as a transparent, refractive, and protective tissue. Recent studies have begun to elucidate the molecular and cellular events involved in the embryonic development, post-natal maturation, and homeostasis of the CE, and how they are regulated by a well-coordinated network of transcription factors. This review summarizes the status of related knowledge and aims to provide insight into the pathophysiology of disorders caused by disruption of CE development, and/or homeostasis.
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Affiliation(s)
| | - Sudha Swamynathan
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15213, USA
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2
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Deng C, Zhang Z, Xu F, Xu J, Ren Z, Godoy-Parejo C, Xiao X, Liu W, Zhou Z, Chen G. Thyroid hormone enhances stem cell maintenance and promotes lineage-specific differentiation in human embryonic stem cells. Stem Cell Res Ther 2022; 13:120. [PMID: 35313973 PMCID: PMC8935725 DOI: 10.1186/s13287-022-02799-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Accepted: 02/13/2022] [Indexed: 11/11/2022] Open
Abstract
Background Thyroid hormone triiodothyronine (T3) is essential for embryogenesis and is commonly used during in vitro fertilization to ensure successful implantation. However, the regulatory mechanisms of T3 during early embryogenesis are largely unknown.
Method To study the impact of T3 on hPSCs, cell survival and growth were evaluated by measurement of cell growth curve, cloning efficiency, survival after passaging, cell apoptosis, and cell cycle status. Pluripotency was evaluated by RT-qPCR, immunostaining and FACS analysis of pluripotency markers. Metabolic status was analyzed using LC–MS/MS and Seahorse XF Cell Mito Stress Test. Global gene expression was analyzed using RNA-seq. To study the impact of T3 on lineage-specific differentiation, cells were subjected to T3 treatment during differentiation, and the outcome was evaluated using RT-qPCR, immunostaining and FACS analysis of lineage-specific markers. Results In this report, we use human pluripotent stem cells (hPSCs) to show that T3 is beneficial for stem cell maintenance and promotes trophoblast differentiation. T3 enhances culture consistency by improving cell survival and passaging efficiency. It also modulates cellular metabolism and promotes energy production through oxidative phosphorylation. T3 helps maintain pluripotency by promoting ERK and SMAD2 signaling and reduces FGF2 dependence in chemically defined culture. Under BMP4 induction, T3 significantly enhances trophoblast differentiation. Conclusion In summary, our study reveals the impact of T3 on stem cell culture through signal transduction and metabolism and highlights its potential role in improving stem cell applications. Supplementary Information The online version contains supplementary material available at 10.1186/s13287-022-02799-y.
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Affiliation(s)
- Chunhao Deng
- Centre of Reproduction, Development and Aging, Faculty of Health Sciences, University of Macau, Macau SAR, China.,Institute of Translational Medicine, Faculty of Health Sciences, University of Macau, Macau SAR, China
| | - Zhaoying Zhang
- Centre of Reproduction, Development and Aging, Faculty of Health Sciences, University of Macau, Macau SAR, China
| | - Faxiang Xu
- Centre of Reproduction, Development and Aging, Faculty of Health Sciences, University of Macau, Macau SAR, China
| | - Jiaqi Xu
- Centre of Reproduction, Development and Aging, Faculty of Health Sciences, University of Macau, Macau SAR, China
| | - Zhili Ren
- Centre of Reproduction, Development and Aging, Faculty of Health Sciences, University of Macau, Macau SAR, China
| | - Carlos Godoy-Parejo
- Centre of Reproduction, Development and Aging, Faculty of Health Sciences, University of Macau, Macau SAR, China
| | - Xia Xiao
- Centre of Reproduction, Development and Aging, Faculty of Health Sciences, University of Macau, Macau SAR, China
| | - Weiwei Liu
- Centre of Reproduction, Development and Aging, Faculty of Health Sciences, University of Macau, Macau SAR, China.,Bioimaging and Stem Cell Core Facility, Faculty of Health Sciences, University of Macau, Macau SAR, China
| | - Zhou Zhou
- State Key Laboratory of Cardiovascular Disease, Beijing Key Laboratory for Molecular Diagnostics of Cardiovascular Diseases, Diagnostic Laboratory Service, Fuwai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100037, China
| | - Guokai Chen
- Centre of Reproduction, Development and Aging, Faculty of Health Sciences, University of Macau, Macau SAR, China. .,Institute of Translational Medicine, Faculty of Health Sciences, University of Macau, Macau SAR, China. .,MoE Frontiers Science Center for Precision Oncology, University of Macau, Macau SAR, China.
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3
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Lea RA, McCarthy A, Boeing S, Fallesen T, Elder K, Snell P, Christie L, Adkins S, Shaikly V, Taranissi M, Niakan KK. KLF17 promotes human naïve pluripotency but is not required for its establishment. Development 2021; 148:272511. [PMID: 34661235 PMCID: PMC8645209 DOI: 10.1242/dev.199378] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 10/11/2021] [Indexed: 12/11/2022]
Abstract
Current knowledge of the transcriptional regulation of human pluripotency is incomplete, with lack of interspecies conservation observed. Single-cell transcriptomics analysis of human embryos previously enabled us to identify transcription factors, including the zinc-finger protein KLF17, that are enriched in the human epiblast and naïve human embryonic stem cells (hESCs). Here, we show that KLF17 is expressed coincident with the known pluripotency-associated factors NANOG and SOX2 across human blastocyst development. We investigate the function of KLF17 using primed and naïve hESCs for gain- and loss-of-function analyses. We find that ectopic expression of KLF17 in primed hESCs is sufficient to induce a naïve-like transcriptome and that KLF17 can drive transgene-mediated resetting to naïve pluripotency. This implies a role for KLF17 in establishing naïve pluripotency. However, CRISPR-Cas9-mediated knockout studies reveal that KLF17 is not required for naïve pluripotency acquisition in vitro. Transcriptome analysis of naïve hESCs identifies subtle effects on metabolism and signalling pathways following KLF17 loss of function, and possible redundancy with other KLF paralogues. Overall, we show that KLF17 is sufficient, but not necessary, for naïve pluripotency under the given in vitro conditions. Summary: Given that KLF17 was shown to be sufficient, but not necessary, to establish naïve pluripotent hESCs, KLF17 might function as a peripheral regulator of human pluripotent stem cells.
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Affiliation(s)
- Rebecca A Lea
- Human Embryo and Stem Cell Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Afshan McCarthy
- Human Embryo and Stem Cell Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Stefan Boeing
- Bioinformatics and Biostatistics Service, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Todd Fallesen
- Crick Advanced Light Microscopy, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Kay Elder
- Bourn Hall Clinic, Bourn, Cambridge CB23 2TN, UK
| | - Phil Snell
- Bourn Hall Clinic, Bourn, Cambridge CB23 2TN, UK
| | | | - Sarah Adkins
- Assisted Reproduction and Gynaecology Centre, London W1G 6LP, UK
| | - Valerie Shaikly
- Assisted Reproduction and Gynaecology Centre, London W1G 6LP, UK
| | | | - Kathy K Niakan
- Human Embryo and Stem Cell Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK.,The Centre for Trophoblast Research, Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, UK
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4
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Zhu W, Du J, Chen Q, Zhang Z, Wu B, Xu J, Li T, Bi Y, Shi H, Li R. Association of UHRF1 gene polymorphisms with oligospermia in Chinese males. J Assist Reprod Genet 2019; 36:2563-2573. [PMID: 31802345 DOI: 10.1007/s10815-019-01614-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 10/14/2019] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND UHRF1 plays an important role in maintaining DNA methylation patterns during spermatogenesis. This study was performed to evaluate the association between UHRF1 gene variations and infertility in males with oligozoospermia in a Chinese population. METHODS In this case-control study of 735 Chinese men, single-nucleotide polymorphism (SNP) genotypes and alleles in the UHRF1 gene were assessed by direct sequencing. The effects of the mutations on UHRF1 transcription were investigated using a dual-luciferase reporter gene assay. RESULTS We identified 24 SNPs, including nine SNPs in the promoter region, three in the 5' untranslated region, five in introns, and seven in exons. Interestingly, the genotype frequencies of SNP rs2656927 (P = 0.014) and rs8103849 (P < 0.001) significantly differed between men with oligozoospermia in case group 1 and normozoospermic men. Moreover, four variants (three were novel) were detected only in the patient group, with two in introns and the others in the promoter region. The results of the luciferase assay showed that the -1615C>T-C and -1562A>G-A alleles increased luciferase activity compared with the -1615C>T-T and -1562A>G-G alleles. CONCLUSIONS We detected two SNPs in the UHRF1 gene showing a significant difference between the case and control groups. Two screened SNPs affected UHRF1 promoter activity, improving the understanding of the pathophysiology of oligozoospermia.
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Affiliation(s)
- Weiqiang Zhu
- NHC Key Laboratory of Birth Defects and Reproductive Health, Chongqing Population and Family Planning Science and Technology Research Institute, Chongqing, China.,NHC Key Laboratory of Reproduction Regulation (Shanghai Institute of Planned Parenthood Research), Pharmacy School, Fudan University, 2140 Xietu Road, Shanghai, 200032, China
| | - Jing Du
- NHC Key Laboratory of Reproduction Regulation (Shanghai Institute of Planned Parenthood Research), Pharmacy School, Fudan University, 2140 Xietu Road, Shanghai, 200032, China
| | - Qing Chen
- NHC Key Laboratory of Birth Defects and Reproductive Health, Chongqing Population and Family Planning Science and Technology Research Institute, Chongqing, China
| | - Zhaofeng Zhang
- NHC Key Laboratory of Reproduction Regulation (Shanghai Institute of Planned Parenthood Research), Pharmacy School, Fudan University, 2140 Xietu Road, Shanghai, 200032, China
| | - Bin Wu
- NHC Key Laboratory of Reproduction Regulation (Shanghai Institute of Planned Parenthood Research), Pharmacy School, Fudan University, 2140 Xietu Road, Shanghai, 200032, China
| | - Jianhua Xu
- NHC Key Laboratory of Reproduction Regulation (Shanghai Institute of Planned Parenthood Research), Pharmacy School, Fudan University, 2140 Xietu Road, Shanghai, 200032, China
| | - Tianqi Li
- NHC Key Laboratory of Reproduction Regulation (Shanghai Institute of Planned Parenthood Research), Pharmacy School, Fudan University, 2140 Xietu Road, Shanghai, 200032, China
| | - Yuan Bi
- NHC Key Laboratory of Reproduction Regulation (Shanghai Institute of Planned Parenthood Research), Pharmacy School, Fudan University, 2140 Xietu Road, Shanghai, 200032, China
| | - Huijuan Shi
- NHC Key Laboratory of Reproduction Regulation (Shanghai Institute of Planned Parenthood Research), Pharmacy School, Fudan University, 2140 Xietu Road, Shanghai, 200032, China.
| | - Runsheng Li
- NHC Key Laboratory of Reproduction Regulation (Shanghai Institute of Planned Parenthood Research), Pharmacy School, Fudan University, 2140 Xietu Road, Shanghai, 200032, China.
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Bialkowska AB, Yang VW, Mallipattu SK. Krüppel-like factors in mammalian stem cells and development. Development 2017; 144:737-754. [PMID: 28246209 DOI: 10.1242/dev.145441] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Krüppel-like factors (KLFs) are a family of zinc-finger transcription factors that are found in many species. Recent studies have shown that KLFs play a fundamental role in regulating diverse biological processes such as cell proliferation, differentiation, development and regeneration. Of note, several KLFs are also crucial for maintaining pluripotency and, hence, have been linked to reprogramming and regenerative medicine approaches. Here, we review the crucial functions of KLFs in mammalian embryogenesis, stem cell biology and regeneration, as revealed by studies of animal models. We also highlight how KLFs have been implicated in human diseases and outline potential avenues for future research.
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Affiliation(s)
- Agnieszka B Bialkowska
- Division of Gastroenterology, Department of Medicine, Stony Brook University School of Medicine, Stony Brook, NY 11794-8176, USA
| | - Vincent W Yang
- Division of Gastroenterology, Department of Medicine, Stony Brook University School of Medicine, Stony Brook, NY 11794-8176, USA.,Department of Physiology and Biophysics, Stony Brook University School of Medicine, Stony Brook, NY 11794-8176, USA
| | - Sandeep K Mallipattu
- Division of Nephrology, Department of Medicine, Stony Brook University School of Medicine, Stony Brook, NY 11794-8176, USA
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6
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Cao Y. Germ layer formation during Xenopus embryogenesis: the balance between pluripotency and differentiation. SCIENCE CHINA-LIFE SCIENCES 2015; 58:336-42. [DOI: 10.1007/s11427-015-4799-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 12/30/2014] [Indexed: 12/31/2022]
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7
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Njaine B, Rocha-Martins M, Vieira-Vieira CH, De-Melo LDB, Linden R, Braas K, May V, Martins RAP, Silveira MS. Pleiotropic functions of pituitary adenylyl cyclase-activating polypeptide on retinal ontogenesis: involvement of KLF4 in the control of progenitor cell proliferation. J Mol Neurosci 2014; 54:430-42. [PMID: 24715357 DOI: 10.1007/s12031-014-0299-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 03/27/2014] [Indexed: 12/11/2022]
Abstract
We showed previously that the neuropeptide pituitary adenylyl cyclase-activating polypeptide (PACAP) negatively regulates proliferation of postnatal rat retinal progenitor cells through the downregulation of cyclin D1 in a cAMP/protein kinase A dependent manner. In the present study, we describe by microarray analysis several putative PACAP targets regulated by different transcription factor families. One of these families is the Sp/Klf family of transcriptional factors capable of regulating cyclin D1, and among members, we demonstrate by immunocytochemistry that KLF4 is expressed throughout rat retinal development by retinal progenitor cells and in most differentiated cell types. Using retinal explants preparations, PACAP treatment can transiently increase Klf4 mRNA levels; from electrophoretic mobility shift assays, PACAP is also able to increase the nuclear KLF4 content. From these results, we suggest that KLF4 may be involved in the anti-proliferative effects of PACAP as one mechanism regulating progenitor cell transition from proliferation to differentiation throughout retinal development.
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Affiliation(s)
- Brian Njaine
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho, 373, Edifício do Centro de Ciencias da Saude, Bloco G, Cidade Universitaria, Ilha do Fundão, 21941-902, Rio de Janeiro, Brazil
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8
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Chiplunkar AR, Curtis BC, Eades GL, Kane MS, Fox SJ, Haar JL, Lloyd JA. The Krüppel-like factor 2 and Krüppel-like factor 4 genes interact to maintain endothelial integrity in mouse embryonic vasculogenesis. BMC DEVELOPMENTAL BIOLOGY 2013; 13:40. [PMID: 24261709 PMCID: PMC4222490 DOI: 10.1186/1471-213x-13-40] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Accepted: 11/20/2013] [Indexed: 11/30/2022]
Abstract
Background Krüppel-like Factor 2 (KLF2) plays an important role in vessel maturation during embryonic development. In adult mice, KLF2 regulates expression of the tight junction protein occludin, which may allow KLF2 to maintain vascular integrity. Adult tamoxifen-inducible Krüppel-like Factor 4 (KLF4) knockout mice have thickened arterial intima following vascular injury. The role of KLF4, and the possible overlapping functions of KLF2 and KLF4, in the developing vasculature are not well-studied. Results Endothelial breaks are observed in a major vessel, the primary head vein (PHV), in KLF2-/-KLF4-/- embryos at E9.5. KLF2-/-KLF4-/- embryos die by E10.5, which is earlier than either single knockout. Gross hemorrhaging of multiple vessels may be the cause of death. E9.5 KLF2-/-KLF4+/- embryos do not exhibit gross hemorrhaging, but cross-sections display disruptions of the endothelial cell layer of the PHV, and these embryos generally also die by E10.5. Electron micrographs confirm that there are gaps in the PHV endothelial layer in E9.5 KLF2-/-KLF4-/- embryos, and show that the endothelial cells are abnormally bulbous compared to KLF2-/- and wild-type (WT). The amount of endothelial Nitric Oxide Synthase (eNOS) mRNA, which encodes an endothelial regulator, is reduced by 10-fold in E9.5 KLF2-/-KLF4-/- compared to KLF2-/- and WT embryos. VEGFR2, an eNOS inducer, and occludin, a tight junction protein, gene expression are also reduced in E9.5 KLF2-/-KLF4-/- compared to KLF2-/- and WT embryos. Conclusions This study begins to define the roles of KLF2 and KLF4 in the embryonic development of blood vessels. It indicates that the two genes interact to maintain an intact endothelial layer. KLF2 and KLF4 positively regulate the eNOS, VEGFR2 and occludin genes. Down-regulation of these genes in KLF2-/-KLF4-/- embryos may result in the observed loss of vascular integrity.
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Affiliation(s)
- Aditi R Chiplunkar
- Department of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, Virginia 23298-0035, USA.
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Gupta D, Harvey SAK, Kenchegowda D, Swamynathan S, Swamynathan SK. Regulation of mouse lens maturation and gene expression by Krüppel-like factor 4. Exp Eye Res 2013; 116:205-18. [PMID: 24076321 DOI: 10.1016/j.exer.2013.09.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Revised: 08/29/2013] [Accepted: 09/12/2013] [Indexed: 02/01/2023]
Abstract
Conditional disruption of Klf4 in the surface ectoderm-derived tissues of the eye results in defective cornea, conjunctiva and the lens. This report describes the effects of disruption of Klf4 in the lens in greater detail. Expression of Klf4, first detected in the embryonic day-12 (E12) mouse lens, peaked at E16 and was decreased in later stages. Early embryonic disruption of Klf4 resulted in a smaller lens with cortical vacuolation and nuclear opacity. Microarray comparison of Klf4CN and WT lens transcriptomes revealed fewer changes in the E16.5 (59 increases, 20 decreases of >1.5-fold) than the PN56 Klf4CN lens (239 increases, 182 decreases of >2-fold). Klf4-target genes in the lens were distinct from those previously identified in the cornea, suggesting disparate functions for Klf4 in these functionally related tissues. Transcripts encoding different crystallins were down-regulated in the Klf4CN lens. Shsp/αB-crystallin promoter activity was stimulated upon co-transfection with pCI-Klf4. Mitochondrial density was significantly higher in the Klf4CN lens epithelial cells, consistent with mitochondrial dysfunction being the most significantly affected pathway within the PN56 Klf4CN lens. The Klf4CN lens contained elevated levels of Alox12 and Alox15 transcripts, less reduced glutathione (GSH) and more oxidized glutathione (GSSG) than the WT, suggesting that it is oxidatively stressed. Although the expression of 2087 genes was modulated during WT lens maturation, transcripts encoding crystallins were abundant at E16.5 and remained stable at PN56. Among the 1065 genes whose expression increased during WT lens maturation, there were 104 Klf4-target genes (9.8%) with decreased expression in the PN56 Klf4CN lens. Taken together, these results demonstrate that Klf4 expression is developmentally regulated in the mouse lens, where it controls the expression of genes associated with lens maturation and redox homeostasis.
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Affiliation(s)
- Divya Gupta
- Department of Ophthalmology, Eye and Ear Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
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10
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Cao Y. Regulation of germ layer formation by pluripotency factors during embryogenesis. Cell Biosci 2013; 3:15. [PMID: 23497659 PMCID: PMC3602094 DOI: 10.1186/2045-3701-3-15] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Accepted: 12/26/2012] [Indexed: 01/07/2023] Open
Abstract
The classical pluripotency factors Oct4, Klf4, Sox2, and Nanog are required for the maintenance of pluripotency and self-renewal of embryonic stem (ES) cells and can reprogram terminally differentiated cells into a pluripotent state. Alteration in the levels of these factors in ES cells will cause differentiation into different lineages, suggesting that they are critical determinants of cell fates. These factors show dynamic expression patterns during embryogenesis, in particular in the pluripotent or multipotent cells of an early stage embryo, implying that they are involved in the cell fate decision during early embryonic development. Functions and the underlying molecular mechanisms have been extensively studied for these factors in ES cells under cultured conditions. However, this does not mean that the results also hold true for intact embryos. In the review, I have summarized and discussed the findings on the functions and the underlying mechanisms of the classical pluripotency factors during early embryogenesis, in particular during germ layer formation.
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Affiliation(s)
- Ying Cao
- Model Animal Research Center of Nanjing University and MOE Key Laboratory of Model Animals for Disease Study, 12 Xuefu Road, Pukou High-Tech Zone, Nanjing, 210061, China.
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LIF maintains progenitor phenotype of endothelial progenitor cells via Krüppel-like factor 4. Microvasc Res 2012; 84:270-7. [PMID: 22835519 DOI: 10.1016/j.mvr.2012.07.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Revised: 06/22/2012] [Accepted: 07/16/2012] [Indexed: 11/24/2022]
Abstract
BACKGROUND Endothelial progenitor cells (EPCs) participate in post-natal vasculogenesis. Maintaining the preliminary progenitor phenotype and good proliferation capacity of EPCs is key to their use in treating cardiovascular ischemic diseases. However, transcriptional regulation in EPCs remains largely unknown. We investigated the effect of leukemia inhibitory factor (LIF) combined with vascular endothelial growth factor (VEGF) on EPCs and the potential roles of Krüppel-like transcription factors (KLFs). METHODS AND RESULTS Co-treatment with LIF and VEGF (100 ng/ml each) (V+L) could increase EPC colony-forming units and CD34 expression, which reflects the EPC progenitor phenotype and alleviated differentiation of EPCs. The effect was associated with Akt activation and increased expression of KLF4. Upregulation of KLF4 induced by V+L could be inhibited by transfection with dominant-negative Akt adenovirus. Furthermore, overexpression of KLF4 in EPCs enhanced the expression of CD34 and alleviated cell differentiation but did not increase the phosphorylation of Akt. CONCLUSIONS LIF combined with VEGF can maintain the preliminary, progenitor phenotype of EPCs and alleviate cell differentiation by upregulating KLF4, which may provide new insights into transcriptional regulation in EPCs.
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Yang WT, Zheng PS. Krüppel-like factor 4 functions as a tumor suppressor in cervical carcinoma. Cancer 2011; 118:3691-702. [PMID: 22170594 DOI: 10.1002/cncr.26698] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Revised: 09/26/2011] [Accepted: 10/20/2011] [Indexed: 11/09/2022]
Abstract
BACKGROUND The Krüppel-like factor 4 (KLF4) protein, a zinc finger transcription factor that is highly expressed in epithelial tissues such as the gut and skin, has been implicated in both tumor suppression and progression. However, the role of KLF4 in human cervical carcinoma is still unclear. METHODS The expression of KLF4 in cervical carcinoma tissues and cervical cancer cell lines was examined with immunohistochemistry and Western blot assay. The effects of KLF4 silencing and overexpression on the cell proliferation, cell viability, and tumor formation of cervical cancer cells were investigated. RESULT KLF4 protein expression showed a pattern of gradual decrease from normal cervix to cervical carcinoma in situ and then to invasive cervical carcinomas (P < .05). Overexpression of KLF4 in SiHa and C33A cells resulted in significantly inhibited cell growth and significantly attenuated tumor formation. Consistently, KLF4 silencing in HeLa cells significantly promoted cell growth and tumor formation. Furthermore, KLF4 overexpression caused cell cycle arrest at the G1/S transition, along with the up-regulated expression of p27(Kip1) protein. Promoter analysis revealed that KLF4 transactivated the expression of p27(Kip1) through the specific motif that is between the nucleotides of -435 and -60 in its promoter. The results from chromatin immunoprecipitation assays demonstrated the physical interaction between KLF4 protein and this specific motif in p27(Kip1) promoter. CONCLUSIONS KLF4 may function as a tumor suppressor in cervical carcinoma by inhibiting cell growth and tumor formation.
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Affiliation(s)
- Wen-Ting Yang
- Department of Reproductive Medicine, First Affiliated Hospital, Xi'an Jiaotong University of Medical School, Xi'an, People's Republic of China
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Macdonald J, Glover JD, Taylor L, Sang HM, McGrew MJ. Characterisation and germline transmission of cultured avian primordial germ cells. PLoS One 2010; 5:e15518. [PMID: 21124737 PMCID: PMC2993963 DOI: 10.1371/journal.pone.0015518] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2010] [Accepted: 10/11/2010] [Indexed: 12/01/2022] Open
Abstract
Background Avian primordial germ cells (PGCs) have significant potential to be used as a cell-based system for the study and preservation of avian germplasm, and the genetic modification of the avian genome. It was previously reported that PGCs from chicken embryos can be propagated in culture and contribute to the germ cell lineage of host birds. Principal Findings We confirm these results by demonstrating that PGCs from a different layer breed of chickens can be propagated for extended periods in vitro. We demonstrate that intracellular signalling through PI3K and MEK is necessary for PGC growth. We carried out an initial characterisation of these cells. We find that cultured PGCs contain large lipid vacuoles, are glycogen rich, and express the stem cell marker, SSEA-1. These cells also express the germ cell-specific proteins CVH and CDH. Unexpectedly, using RT-PCR we show that cultured PGCs express the pluripotency genes c-Myc, cKlf4, cPouV, cSox2, and cNanog. Finally, we demonstrate that the cultured PGCs will migrate to and colonise the forming gonad of host embryos. Male PGCs will colonise the female gonad and enter meiosis, but are lost from the gonad during sexual development. In male hosts, cultured PGCs form functional gametes as demonstrated by the generation of viable offspring. Conclusions The establishment of in vitro cultures of germline competent avian PGCs offers a unique system for the study of early germ cell differentiation and also a comparative system for mammalian germ cell development. Primary PGC lines will form the basis of an alternative technique for the preservation of avian germplasm and will be a valuable tool for transgenic technology, with both research and industrial applications.
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Affiliation(s)
- Joni Macdonald
- The Roslin Institute and Royal Dick School of Veterinary Studies, University of Edinburgh, Roslin, United Kingdom
| | - James D. Glover
- The Roslin Institute and Royal Dick School of Veterinary Studies, University of Edinburgh, Roslin, United Kingdom
| | - Lorna Taylor
- The Roslin Institute and Royal Dick School of Veterinary Studies, University of Edinburgh, Roslin, United Kingdom
| | - Helen M. Sang
- The Roslin Institute and Royal Dick School of Veterinary Studies, University of Edinburgh, Roslin, United Kingdom
| | - Michael J. McGrew
- The Roslin Institute and Royal Dick School of Veterinary Studies, University of Edinburgh, Roslin, United Kingdom
- * E-mail:
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Young RD, Swamynathan SK, Boote C, Mann M, Quantock AJ, Piatigorsky J, Funderburgh JL, Meek KM. Stromal edema in klf4 conditional null mouse cornea is associated with altered collagen fibril organization and reduced proteoglycans. Invest Ophthalmol Vis Sci 2009; 50:4155-61. [PMID: 19387067 DOI: 10.1167/iovs.09-3561] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Klf4, one of the highly expressed transcription factors in the mouse cornea, plays an important role in maturation and maintenance of the ocular surface. In this study, the structure and proteoglycan composition of the Klf4 conditional null (Klf4CN) corneal stroma was investigated, to further characterize the previously reported Klf4CN stromal edema. METHODS Collagen fibril spacing and diameter were calculated from scattering intensity profiles from small angle synchrotron x-ray scattering patterns obtained across the cornea along a vertical meridian at 0.5-mm intervals. Collagen fibril organization and proteoglycans were visualized by electron microscopy (EM), with or without the cationic dye cuprolinic blue. Proteoglycans and glycosaminoglycans were further analyzed by fluorophore-assisted carbohydrate electrophoresis (FACE) and immunoblot analysis. Q-RT-PCR was used to measure the transcript levels. RESULTS In the central cornea, the average collagen interfibrillar Bragg spacing increased from 44.5 nm (SD +/-1.8) in wild-type to 66.5 nm (SD +/-2.3) in Klf4CN, as measured by x-ray scattering and confirmed by EM. Mean collagen fibril diameter increased from 32 nm (SD +/-0.4) in wild-type to 42.3 nm (SD +/-4.8) in Klf4CN corneal stroma. Downregulation of proteoglycans detected by EM in the Klf4CN stroma was confirmed by FACE and immunoblot analysis. Q-RT-PCR showed that, whereas the Klf4CN corneal proteoglycan transcript levels remained unchanged, matrix metalloproteinase (MMP) transcript levels were significantly upregulated. CONCLUSIONS The Klf4CN corneal stromal edema is characterized by increased collagen interfibrillar spacing and increased diameter of individual fibrils. The stroma also exhibits reduced interfibrillar proteoglycans throughout, which is possibly caused by increased expression of MMPs.
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Affiliation(s)
- Robert D Young
- Structural Biophysics Group, School of Optometry and Vision Sciences, Cardiff University, Cardiff, Wales, United Kingdom
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Cho SD, Chintharlapalli S, Abdelrahim M, Papineni S, Liu S, Guo J, Lei P, Abudayyeh A, Safe S. 5,5'-Dibromo-bis(3'-indolyl)methane induces Kruppel-like factor 4 and p21 in colon cancer cells. Mol Cancer Ther 2008; 7:2109-20. [PMID: 18645021 DOI: 10.1158/1535-7163.mct-07-2311] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Bis(3'-indolyl)methane (DIM) is a metabolite of the phytochemical indole-3-carbinol, and both compounds exhibit a broad spectrum of anticancer activities. We have developed a series of synthetic symmetrical ring-substituted DIM analogues, including 5,5'-dibromoDIM, which are more potent than DIM as inhibitors of cancer cell and tumor growth. In colon cancer cells, 5,5'-dibromoDIM decreased cell proliferation and inhibited G(0)-G(1)- to S-phase progression, and this was accompanied by induction of the cyclin-dependent kinase inhibitor p21 in HT-29 and RKO colon cancer cells. Mechanistic studies showed that induction of p21 in both RKO (p53 wild-type) and HT-29 (p53 mutant) cells by 5,5'-dibromoDIM was Krüppel-like factor 4 (KLF4) dependent, and induction of p53 in RKO cells was also KLF4 dependent. Analysis of the p21 promoter in p53-dependent RKO cells showed that 5,5'-dibromoDIM activated p21 gene expression through the proximal GC-rich sites 1 and 2, and chromatin immunoprecipitation assays showed that KLF4 and p53 bound to this region of the promoter, whereas in HT-29 cells unidentified upstream cis-elements were required for induction of p21. 5,5'-DibromoDIM (30 mg/kg/d) also inhibited tumor growth and induced p21 in athymic nude mice bearing RKO cells as xenografts, showing that ring-substituted DIM such as 5,5'-dibromoDIM represent a novel class of mechanism-based drugs for clinical treatment of colon cancer.
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Affiliation(s)
- Sung Dae Cho
- Institute of Biosciences and Technology, Texas A&M University Health Science Center, College Station, TX 77843-4466, USA
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Swamynathan SK, Davis J, Piatigorsky J. Identification of candidate Klf4 target genes reveals the molecular basis of the diverse regulatory roles of Klf4 in the mouse cornea. Invest Ophthalmol Vis Sci 2008; 49:3360-70. [PMID: 18469187 DOI: 10.1167/iovs.08-1811] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
PURPOSE Krüppel-like factor 4 (Klf4) plays a crucial role in the development and maintenance of the mouse cornea. In the current study, wild-type (WT) and Klf4-conditional null (Klf4CN) corneal gene expression patterns were examined, to gain understanding of the molecular basis of the Klf4CN corneal phenotype. METHODS Expression of more than 22,000 genes in 10 WT and Klf4CN corneas was compared by microarrays, analyzed using BRB ArrayTools (National Cancer Institute, Bethesda, MD) and validated by Q-RT-PCR. Transient cotransfections were used to test whether Klf4 activates the aquaporin-3, Aldh3a1, and TKT promoters. RESULTS Scatterplot analysis identified 740 and 529 genes up- and downregulated by more than twofold, respectively, in the Klf4CN corneas. Cell cycle activators were upregulated, whereas the inhibitors were downregulated, consistent with the increased Klf4CN corneal epithelial cell proliferation. Desmosomal components were downregulated, consistent with the Klf4CN corneal epithelial fragility. Downregulation of aquaporin-3, detected by microarray, was confirmed by immunoblot and immunohistochemistry. Aquaporin-3 promoter activity was stimulated 7- to 10-fold by cotransfection with pCI-Klf4. The corneal crystallins Aldh3A1 and TKT were downregulated in the Klf4CN cornea, and their respective promoter activities were upregulated 16- and 9-fold by pCI-Klf4 in cotransfections. The expression of epidermal keratinocyte differentiation markers was affected in the Klf4CN cornea. Although the cornea-specific keratin-12 was downregulated, most other keratins were upregulated, suggesting hyperkeratosis. CONCLUSIONS Functionally diverse candidate Klf4 target genes were identified, revealing the molecular basis of the diverse aspects of the Klf4CN corneal phenotype. These results establish Klf4 as an important node in the genetic network of transcription factors regulating the corneal homeostasis.
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Affiliation(s)
- Shivalingappa K Swamynathan
- Department of Ophthalmology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA.
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Behr R, Deller C, Godmann M, Muller T, Bergmann M, Ivell R, Steger K. Kruppel-like factor 4 expression in normal and pathological human testes. Mol Hum Reprod 2007; 13:815-20. [DOI: 10.1093/molehr/gam064] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
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Swamynathan SK, Katz JP, Kaestner KH, Ashery-Padan R, Crawford MA, Piatigorsky J. Conditional deletion of the mouse Klf4 gene results in corneal epithelial fragility, stromal edema, and loss of conjunctival goblet cells. Mol Cell Biol 2006; 27:182-94. [PMID: 17060454 PMCID: PMC1800665 DOI: 10.1128/mcb.00846-06] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The Krüppel-like transcription factor KLF4 is among the most highly expressed transcription factors in the mouse cornea (B. Norman, J. Davis, and J. Piatigorsky, Investig. Ophthalmol. Vis. Sci. 45:429-440, 2004). Here, we deleted the Klf4 gene selectively in the surface ectoderm-derived structures of the eye (cornea, conjunctiva, eyelids, and lens) by mating Klf4-LoxP mice (J. P. Katz, N. Perreault, B. G. Goldstein, C. S. Lee, P. A. Labosky, V. W. Yang, and K. H. Kaestner, Development 129:2619-2628, 2002) with Le-Cre mice (R. Ashery-Padan, T. Marquardt, X. Zhou, and P. Gruss, Genes Dev. 14:2701-2711, 2000). Klf4 conditional null (Klf4CN) embryos developed normally, and the adult mice were viable and fertile. Unlike the wild type, the Klf4CN cornea consisted of three to four epithelial cell layers; swollen, vacuolated basal epithelial and endothelial cells; and edematous stroma. The conjunctiva lacked goblet cells, and the anterior cortical lens was vacuolated in Klf4CN mice. Excessive cell sloughing resulted in fewer epithelial cell layers in spite of increased cell proliferation at the Klf4CN ocular surface. Expression of the keratin-12 and aquaporin-5 genes was downregulated, consistent with the Klf4CN corneal epithelial fragility and stromal edema, respectively. These observations provide new insights into the role of KLF4 in postnatal maturation and maintenance of the ocular surface and suggest that the Klf4CN mouse is a useful model for investigating ocular surface pathologies such as dry eye, Meesmann's dystrophy, and Steven's-Johnson syndrome.
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Affiliation(s)
- Shivalingappa K Swamynathan
- Laboratory of Molecular and Developmental Biology, National Eye Institute/NIH, 7 Memorial Drive, Room 129, Bethesda, MD 20892, USA.
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Abstract
Recent analyses revealed that Krüppel-like factors (KLFs) play important roles in both normal development and carcinogenesis. Of the 16 known KLFs, KLF4 has been shown to be involved in the regulation of proliferation, differentiation and tumorigenesis of gastrointestinal tract epithelium. Clinical, experimental and mechanistic findings indicate that KLF4 is a bona fide tumor suppressor for both gastric and colorectal cancers. In this review, we summarize how this growing area of research has formed and the challenging new frontiers for better understanding of the oncogenic potential of the KLFs.
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Affiliation(s)
- Daoyan Wei
- Department of Gastrointestinal Medical Oncology, Department of Neurosurgery and Department of Cancer Biology, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA
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