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Gu S, Huang Q, Sun C, Wen C, Yang N. Transcriptomic and epigenomic insights into pectoral muscle fiber formation at the late embryonic development in pure chicken lines. Poult Sci 2024; 103:103882. [PMID: 38833745 PMCID: PMC11190745 DOI: 10.1016/j.psj.2024.103882] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 05/16/2024] [Accepted: 05/17/2024] [Indexed: 06/06/2024] Open
Abstract
Long-term intensive genetic selection has led to significant differences between broiler and layer chickens, which are evident during the embryonic period. Despite this, there is a paucity of research on the genetic regulation of the initial formation of muscle fiber morphology in chick embryos. Embryonic d 17 (E17) is the key time point for myoblast fusion completion and muscle fiber morphology formation in chickens. This study aimed to explore the genetic regulatory mechanisms underlying the early muscle fiber morphology establishment in broiler chickens of Cornish (CC) and White Plymouth Rock (RR) and layer chickens of White Leghorn (WW) at E17 using the transcriptomic and chromatin accessibility sequencing of pectoral major muscles. The results showed that broiler chickens exhibited significant higher embryo weight and pectoral major muscle weight at E17 compared to layer chickens (P = 0.000). A total of 1,278, 1,248, and 892 differentially expressed genes (DEGs) of RNA-seq data were identified between CC vs. WW, RR vs. WW, and CC vs. RR, separately. All DEGs were combined for cluster analysis and they were divided into 6 clusters, including cluster 1 with higher expression in broilers and cluster 6 with higher expression in layers. DEGs in cluster 1 were enriched in terms related to macrophage activation (P = 0.002) and defense response to bacteria (P = 0.002), while DEGs in cluster 6 showed enrichment in protein-DNA complex (P = 0.003) and monooxygenase activity (P = 0.000). ATAC-seq data analysis identified a total of 38,603 peaks, with 13,051 peaks for CC, 18,780 peaks for RR, and 6,772 peaks for WW. Integrative analysis of transcriptomic and chromatin accessibility data revealed GOLM1, ISLR2, and TOPAZ1 were commonly upregulated genes in CC and RR. Furthermore, screening of all upregulated DEGs in cluster 1 from CC and RR identified GOLM1, ISLR2, and HNMT genes associated with neuroimmune functions and MYOM3 linked to muscle morphology development, showing significantly elevated expression in broiler chickens compared to layer chickens. These findings suggest active neural system connectivity during the initial formation of muscle fiber morphology in embryonic period, highlighting the early interaction between muscle fiber formation morphology and the nervous system. This study provides novel insights into late chick embryo development and lays a deeper foundation for further research.
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Affiliation(s)
- Shuang Gu
- State Key Laboratory of Animal Biotech Breeding and Frontier Science Center for Molecular Design Breeding, China Agricultural University, Beijing, 100193, China; National Engineering Laboratory for Animal Breeding and Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture and Rural Affairs, Department of Animal Genetics and Breeding, College of Animal Science and Technology China Agricultural University, Beijing 100193, China
| | - Qiang Huang
- State Key Laboratory of Animal Biotech Breeding and Frontier Science Center for Molecular Design Breeding, China Agricultural University, Beijing, 100193, China; National Engineering Laboratory for Animal Breeding and Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture and Rural Affairs, Department of Animal Genetics and Breeding, College of Animal Science and Technology China Agricultural University, Beijing 100193, China
| | - Congjiao Sun
- State Key Laboratory of Animal Biotech Breeding and Frontier Science Center for Molecular Design Breeding, China Agricultural University, Beijing, 100193, China; National Engineering Laboratory for Animal Breeding and Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture and Rural Affairs, Department of Animal Genetics and Breeding, College of Animal Science and Technology China Agricultural University, Beijing 100193, China; Sanya Institute of China Agricultural University, Hainan 572025, China
| | - Chaoliang Wen
- State Key Laboratory of Animal Biotech Breeding and Frontier Science Center for Molecular Design Breeding, China Agricultural University, Beijing, 100193, China; National Engineering Laboratory for Animal Breeding and Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture and Rural Affairs, Department of Animal Genetics and Breeding, College of Animal Science and Technology China Agricultural University, Beijing 100193, China; Sanya Institute of China Agricultural University, Hainan 572025, China
| | - Ning Yang
- State Key Laboratory of Animal Biotech Breeding and Frontier Science Center for Molecular Design Breeding, China Agricultural University, Beijing, 100193, China; National Engineering Laboratory for Animal Breeding and Key Laboratory of Animal Genetics, Breeding and Reproduction, Ministry of Agriculture and Rural Affairs, Department of Animal Genetics and Breeding, College of Animal Science and Technology China Agricultural University, Beijing 100193, China; Sanya Institute of China Agricultural University, Hainan 572025, China.
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Wang J, Xing C, Wang H, Zhang H, Wei W, Xu J, Liu Y, Guo X, Jiang R. Identification of key modules and hub genes involved in regulating the feather follicle development of Wannan chickens using WGCNA. Poult Sci 2024; 103:103903. [PMID: 38908121 PMCID: PMC11253687 DOI: 10.1016/j.psj.2024.103903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2024] [Revised: 05/21/2024] [Accepted: 05/22/2024] [Indexed: 06/24/2024] Open
Abstract
Carcass appearance is important economic trait, which affects customers in making purchase decisions. Both density and diameter of feather follicles are two important indicators of carcass appearance. However, the regulatory network and key genes be involved in feather follicle development remain poorly understood. To identify key genes and modules that involved in feather follicle development in chickens, 16 transcriptome datasets of Wannan chickens skin tissue (3 birds at the E9, E11, and E14, respectively, and 7 birds at the 12W) were used for weighted gene co-expression network analysis (WGCNA) analysis, and 12 skin tissue samples (3 birds for each stage) were selected for DEGs analysis. A total of 5,025, 2,337, and 10,623 DEGs were identified in 3 comparison groups, including the E9 vs. E11, the E11 vs. E14, and the E14 vs. 12W. Additionally, 31 co-expression gene modules were identified by WGCNA and the dark-orange, cyan, and blue module were found to be significantly associated with feather follicle development (p < 0.01). In total, 92,898 and 8,448 hub genes were obtained in the dark-orange, cyan, and blue modules, respectively. We focused on the cyan and blue modules, as 6 and 336 hub genes of these modules were identified to overlap with the DEGs of the three comparison groups, respectively. The 6 overlapped genes such as LAMC2, COL6A3, and COL6A2 etc., were over-represented in 12 categories such as focal adhesion and ECM-receptor interaction signaling pathway. Among the 336 genes that overlapped between the blue module and different DEGs comparison groups several genes including WNT7A and WNT9B were enriched in Wnt and ECM-receptor interaction signaling pathway. These results suggested that the LAMC2, COL6A3, COL6A2, WNT7A, and WNT9B genes may play a crucial role in the regulation of feather follicle development in Wannan chickens. Our results provided a reference for the molecular regulatory network and key genes in the development of feather follicles and contribute to molecular breeding for carcass appearance traits in chickens.
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Affiliation(s)
- Jiangxian Wang
- College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, China
| | - Chaohui Xing
- College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, China
| | - Hao Wang
- College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, China
| | - Hong Zhang
- College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, China
| | - Wei Wei
- College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, China
| | - Jinmei Xu
- College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, China
| | - Yanan Liu
- College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, China
| | - Xing Guo
- College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, China
| | - Runshen Jiang
- College of Animal Science and Technology, Anhui Agricultural University, Hefei 230036, China.
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Chan YF, Lu CW, Kuo HC, Hung CM. A chromosome-level genome assembly of the Asian house martin implies potential genes associated with the feathered-foot trait. G3 (BETHESDA, MD.) 2024; 14:jkae077. [PMID: 38607414 PMCID: PMC11152083 DOI: 10.1093/g3journal/jkae077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2024] [Revised: 03/04/2024] [Accepted: 03/27/2024] [Indexed: 04/13/2024]
Abstract
The presence of feathers is a vital characteristic among birds, yet most modern birds had no feather on their feet. The discoveries of feathers on the hind limbs of basal birds and dinosaurs have sparked an interest in the evolutionary origin and genetic mechanism of feathered feet. However, the majority of studies investigating the genes associated with this trait focused on domestic populations. Understanding the genetic mechanism underpinned feathered-foot development in wild birds is still in its infancy. Here, we assembled a chromosome-level genome of the Asian house martin (Delichon dasypus) using the long-read High Fidelity sequencing approach to initiate the search for genes associated with its feathered feet. We employed the whole-genome alignment of D. dasypus with other swallow species to identify high-SNP regions and chromosomal inversions in the D. dasypus genome. After filtering out variations unrelated to D. dasypus evolution, we found six genes related to feather development near the high-SNP regions. We also detected three feather development genes in chromosomal inversions between the Asian house martin and the barn swallow genomes. We discussed their association with the wingless/integrated (WNT), bone morphogenetic protein, and fibroblast growth factor pathways and their potential roles in feathered-foot development. Future studies are encouraged to utilize the D. dasypus genome to explore the evolutionary process of the feathered-foot trait in avian species. This endeavor will shed light on the evolutionary path of feathers in birds.
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Affiliation(s)
- Yuan-Fu Chan
- Biodiversity Research Center, Academia Sinica, Taipei 11529, Taiwan
| | - Chia-Wei Lu
- Biodiversity Research Center, Academia Sinica, Taipei 11529, Taiwan
| | - Hao-Chih Kuo
- Biodiversity Research Center, Academia Sinica, Taipei 11529, Taiwan
| | - Chih-Ming Hung
- Biodiversity Research Center, Academia Sinica, Taipei 11529, Taiwan
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Ji G, Zhang M, Tu Y, Liu Y, Shan Y, Ju X, Zou J, Shu J, Sheng Z, Li H. Molecular Regulatory Mechanisms in Chicken Feather Follicle Morphogenesis. Genes (Basel) 2023; 14:1646. [PMID: 37628697 PMCID: PMC10454116 DOI: 10.3390/genes14081646] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 08/10/2023] [Accepted: 08/16/2023] [Indexed: 08/27/2023] Open
Abstract
In China, the sale of freshly slaughtered chickens is becoming increasingly popular in comparison with that of live chickens, and due to this emerging trend, the skin and feather follicle traits of yellow-feathered broilers have attracted a great deal of research attention. The feather follicle originates from the interaction between the epidermis and dermis in the early embryonic stage. Feather follicle morphogenesis is regulated by the Wnt, ectodysplasin (Eda), epidermal growth factor (EGF), fibroblast growth factor (FGF), bone morphogenetic protein (BMP), sonic hedgehog (Shh), Notch, and other signaling pathways that exist in epithelial and mesenchymal cells. The Wnt pathway is essential for feather follicle and feather morphogenesis. Eda interacts with Wnt to induce FGF expression, which attracts mesenchymal cell movement and aggregates to form feather follicle primordia. BMP acts as an inhibitor of the above signaling pathways to limit the size of the feather tract and distance between neighboring feather primordia in a dose-dependent manner. The Notch/Delta pathway can interact with the FGF pathway to promote feather bud formation. While not a part of the early morphogenesis of feather follicles, Shh and BMP signaling are involved in late feather branching. This review summarizes the roles of miRNAs/lncRNA in the regulation of feather follicle and feather growth and development and suggests topics that need to be solved in a future study. This review focuses on the regulatory mechanisms involved in feather follicle morphogenesis and analyzes the impact of SNP sites on feather follicle traits in poultry. This work may help us to understand the molecular regulatory networks influencing feather follicle growth and provide basic data for poultry carcass quality.
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Affiliation(s)
- Gaige Ji
- Key Laboratory for Poultry Genetics and Breeding of Jiangsu Province, Chinese Academy of Agricultural Science, Institute of Poultry Science, Yangzhou 225125, China
| | - Ming Zhang
- Key Laboratory for Poultry Genetics and Breeding of Jiangsu Province, Chinese Academy of Agricultural Science, Institute of Poultry Science, Yangzhou 225125, China
| | - Yunjie Tu
- Key Laboratory for Poultry Genetics and Breeding of Jiangsu Province, Chinese Academy of Agricultural Science, Institute of Poultry Science, Yangzhou 225125, China
| | - Yifan Liu
- Key Laboratory for Poultry Genetics and Breeding of Jiangsu Province, Chinese Academy of Agricultural Science, Institute of Poultry Science, Yangzhou 225125, China
| | - Yanju Shan
- Key Laboratory for Poultry Genetics and Breeding of Jiangsu Province, Chinese Academy of Agricultural Science, Institute of Poultry Science, Yangzhou 225125, China
| | - Xiaojun Ju
- Key Laboratory for Poultry Genetics and Breeding of Jiangsu Province, Chinese Academy of Agricultural Science, Institute of Poultry Science, Yangzhou 225125, China
| | - Jianmin Zou
- Key Laboratory for Poultry Genetics and Breeding of Jiangsu Province, Chinese Academy of Agricultural Science, Institute of Poultry Science, Yangzhou 225125, China
| | - Jingting Shu
- Key Laboratory for Poultry Genetics and Breeding of Jiangsu Province, Chinese Academy of Agricultural Science, Institute of Poultry Science, Yangzhou 225125, China
| | - Zhongwei Sheng
- Key Laboratory for Poultry Genetics and Breeding of Jiangsu Province, Chinese Academy of Agricultural Science, Institute of Poultry Science, Yangzhou 225125, China
| | - Hua Li
- School of Life Science and Engineering, Foshan University, Foshan 528231, China
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Zhu XN, Wang YZ, Li C, Wu HY, Zhang R, Hu XX, Zhang R, Hu XX. Chicken chromatin accessibility atlas accelerates epigenetic annotation of birds and gene fine-mapping associated with growth traits. Zool Res 2023; 44:53-62. [PMID: 36317479 PMCID: PMC9841184 DOI: 10.24272/j.issn.2095-8137.2022.228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The development of epigenetic maps, such as the ENCODE project in humans, provides resources for gene regulation studies and a reference for research of disease-related regulatory elements. However, epigenetic information, such as a bird-specific chromatin accessibility atlas, is currently lacking for the thousands of bird species currently described. The major genomic difference between birds and mammals is their shorter introns and intergenic distances, which seriously hinders the use of humans and mice as a reference for studying the function of important regulatory regions in birds. In this study, using chicken as a model bird species, we systematically compiled a chicken chromatin accessibility atlas using 53 Assay of Transposase Accessible Chromatin sequencing (ATAC-seq) samples across 11 tissues. An average of 50 796 open chromatin regions were identified per sample, cumulatively accounting for 20.36% of the chicken genome. Tissue specificity was largely reflected by differences in intergenic and intronic peaks, with specific functional regulation achieved by two mechanisms: recruitment of several sequence-specific transcription factors and direct regulation of adjacent functional genes. By integrating data from genome-wide association studies, our results suggest that chicken body weight is driven by different regulatory variants active in growth-relevant tissues. We propose CAB39L (active in the duodenum), RCBTB1 (muscle and liver), and novel long non-coding RNA ENSGALG00000053256 (bone) as candidate genes regulating chicken body weight. Overall, this study demonstrates the value of epigenetic data in fine-mapping functional variants and provides a compendium of resources for further research on the epigenetics and evolution of birds and mammals.
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Affiliation(s)
- Xiao-Ning Zhu
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Yu-Zhe Wang
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, China,National Research Facility for Phenotypic and Genotypic Analysis of Model Animals (Beijing), China Agricultural University, Beijing 100193, China,E-mail:
| | - Chong Li
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Han-Yu Wu
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, China,National Research Facility for Phenotypic and Genotypic Analysis of Model Animals (Beijing), China Agricultural University, Beijing 100193, China
| | - Ran Zhang
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Xiao-Xiang Hu
- State Key Laboratory of Agrobiotechnology, College of Biological Sciences, China Agricultural University, Beijing 100193, China,National Research Facility for Phenotypic and Genotypic Analysis of Model Animals (Beijing), China Agricultural University, Beijing 100193, China,
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Lachner J, Ehrlich F, Wielscher M, Farlik M, Hermann M, Tschachler E, Eckhart L. Single-cell transcriptomics defines keratinocyte differentiation in avian scutate scales. Sci Rep 2022; 12:126. [PMID: 34997067 PMCID: PMC8742010 DOI: 10.1038/s41598-021-04082-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 12/09/2021] [Indexed: 11/24/2022] Open
Abstract
The growth of skin appendages, such as hair, feathers and scales, depends on terminal differentiation of epidermal keratinocytes. Here, we investigated keratinocyte differentiation in avian scutate scales. Cells were isolated from the skin on the legs of 1-day old chicks and subjected to single-cell transcriptomics. We identified two distinct populations of differentiated keratinocytes. The first population was characterized by mRNAs encoding cysteine-rich keratins and corneous beta-proteins (CBPs), also known as beta-keratins, of the scale type, indicating that these cells form hard scales. The second population of differentiated keratinocytes contained mRNAs encoding cysteine-poor keratins and keratinocyte-type CBPs, suggesting that these cells form the soft interscale epidermis. We raised an antibody against keratin 9-like cysteine-rich 2 (KRT9LC2), which is encoded by an mRNA enriched in the first keratinocyte population. Immunostaining confirmed expression of KRT9LC2 in the suprabasal epidermal layers of scutate scales but not in interscale epidermis. Keratinocyte differentiation in chicken leg skin resembled that in human skin with regard to the transcriptional upregulation of epidermal differentiation complex genes and genes involved in lipid metabolism and transport. In conclusion, this study defines gene expression programs that build scutate scales and interscale epidermis of birds and reveals evolutionarily conserved keratinocyte differentiation genes.
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Affiliation(s)
- Julia Lachner
- Department of Dermatology, Medical University of Vienna, Vienna, Austria
| | - Florian Ehrlich
- Department of Dermatology, Medical University of Vienna, Vienna, Austria
| | - Matthias Wielscher
- Department of Dermatology, Medical University of Vienna, Vienna, Austria
| | - Matthias Farlik
- Department of Dermatology, Medical University of Vienna, Vienna, Austria
| | - Marcela Hermann
- Department of Medical Biochemistry, Medical University of Vienna, Vienna, Austria
| | - Erwin Tschachler
- Department of Dermatology, Medical University of Vienna, Vienna, Austria
| | - Leopold Eckhart
- Department of Dermatology, Medical University of Vienna, Vienna, Austria.
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Chen CK, Juan WT, Liang YC, Wu P, Chuong CM. Making region-specific integumentary organs in birds: evolution and modifications. Curr Opin Genet Dev 2021; 69:103-111. [PMID: 33780743 DOI: 10.1016/j.gde.2021.02.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Revised: 02/20/2021] [Accepted: 02/24/2021] [Indexed: 11/16/2022]
Abstract
Birds are the most diversified terrestrial vertebrates due to highly diverse integumentary organs that enable robust adaptability to various eco-spaces. Here we show that this complexity is built upon multi-level regional specifications. Across-the-body (macro-) specification includes the evolution of beaks and feathers as new integumentary organs that are formed with regional specificity. Within-an-organ (micro-) specification involves further modifications of organ shapes. We review recent progress in elucidating the molecular mechanisms underlying feather diversification as an example. (1) β-Keratin gene clusters are regulated by typical enhancers or high order chromatin looping to achieve macro- and micro-level regional specification, respectively. (2) Multi-level symmetry-breaking of feather branches confers new functional forms. (3) Complex color patterns are produced by combinations of macro-patterning and micro-patterning processes. The integration of these findings provides new insights toward the principle of making a robustly adaptive bio-interface.
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Affiliation(s)
- Chih-Kuan Chen
- Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA; The IEGG and Animal Biotechnology Center, National Chung Hsing University, Taichung 402, Taiwan
| | - Wen-Tau Juan
- Integrative Stem Cell Center, China Medical University Hospital, Taichung 40447, Taiwan
| | - Ya-Chen Liang
- Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
| | - Ping Wu
- Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
| | - Cheng-Ming Chuong
- Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA.
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Abstract
Nearly one-third of adults over the age of 65 have lost all their teeth. We set out to understand tooth renewal in animals that have replacement and regeneration capabilities. Using cichlid fishes and mouse models, we discovered plasticity between tooth and taste bud progenitor cell derivatives, mediated by BMP. Our results suggest that oral organs have surprising regenerative capabilities and can be manipulated to express characteristics of different tissue types. In Lake Malawi cichlids, each tooth is replaced in one-for-one fashion every ∼20 to 50 d, and taste buds (TBs) are continuously renewed as in mammals. These structures are colocalized in the fish mouth and throat, from the point of initiation through adulthood. Here, we found that replacement teeth (RT) share a continuous band of epithelium with adjacent TBs and that both organs coexpress stem cell factors in subsets of label-retaining cells. We used RNA-seq to characterize transcriptomes of RT germs and TB-bearing oral epithelium. Analysis revealed differential usage of developmental pathways in RT compared to TB oral epithelia, as well as a repertoire of genome paralogues expressed complimentarily in each organ. Notably, BMP ligands were expressed in RT but excluded from TBs. Morphant fishes bathed in a BMP chemical antagonist exhibited RT with abrogated shh expression in the inner dental epithelium (IDE) and ectopic expression of calb2 (a TB marker) in these very cells. In the mouse, teeth are located on the jaw margin while TBs and other oral papillae are located on the tongue. Previous study reported that tongue intermolar eminence (IE) oral papillae of Follistatin (a BMP antagonist) mouse mutants exhibited dysmorphic invagination. We used these mutants to demonstrate altered transcriptomes and ectopic expression of dental markers in tongue IE. Our results suggest that vertebrate oral epithelium retains inherent plasticity to form tooth and taste-like cell types, mediated by BMP specification of progenitor cells. These findings indicate underappreciated epithelial cell populations with promising potential in bioengineering and dental therapeutics.
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Pigeon foot feathering reveals conserved limb identity networks. Dev Biol 2019; 454:128-144. [PMID: 31247188 DOI: 10.1016/j.ydbio.2019.06.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 06/19/2019] [Accepted: 06/20/2019] [Indexed: 12/15/2022]
Abstract
The tetrapod limb is a stunning example of evolutionary diversity, with dramatic variation not only among distantly related species, but also between the serially homologous forelimbs (FLs) and hindlimbs (HLs) within species. Despite this variation, highly conserved genetic and developmental programs underlie limb development and identity in all tetrapods, raising the question of how limb diversification is generated from a conserved toolkit. In some breeds of domestic pigeon, shifts in the expression of two conserved limb identity transcription factors, PITX1 and TBX5, are associated with the formation of feathered HLs with partial FL identity. To determine how modulation of PITX1 and TBX5 expression affects downstream gene expression, we compared the transcriptomes of embryonic limb buds from pigeons with scaled and feathered HLs. We identified a set of differentially expressed genes enriched for genes encoding transcription factors, extracellular matrix proteins, and components of developmental signaling pathways with important roles in limb development. A subset of the genes that distinguish scaled and feathered HLs are also differentially expressed between FL and scaled HL buds in pigeons, pinpointing a set of gene expression changes downstream of PITX1 and TBX5 in the partial transformation from HL to FL identity. We extended our analyses by comparing pigeon limb bud transcriptomes to chicken, anole lizard, and mammalian datasets to identify deeply conserved PITX1- and TBX5-responsive components of the limb identity program. Our analyses reveal a suite of predominantly low-level gene expression changes that are conserved across amniotes to regulate the identity of morphologically distinct limbs.
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