1
|
Feng M, Gao B, Ruiz D, Garcia LR, Sun Q. Bacterial vitamin B6 is required for post-embryonic development in C. elegans. Commun Biol 2024; 7:367. [PMID: 38532074 PMCID: PMC10966028 DOI: 10.1038/s42003-024-05992-2] [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: 07/17/2023] [Accepted: 02/29/2024] [Indexed: 03/28/2024] Open
Abstract
Nutritional intake influences animal growth, reproductive capacity, and survival of animals. Under nutrition deficiency, animal developmental arrest occurs as an adaptive strategy to survive. However, the nutritional basis and the underlying nutrient sensing mechanism essential for animal regrowth after developmental arrest remain to be explored. In Caenorhabditis elegans, larvae undergo early developmental arrest are stress resistant, and they require certain nutrients to recover postembryonic development. Here, we investigated the developmental arrest in C. elegans feeding on Lactiplantibacillus plantarum, and the rescue of the diapause state with trace supplementation of Escherichia coli. We performed a genome-wide screen using 3983 individual gene deletion E. coli mutants and identified E. coli genes that are indispensable for C. elegans larval growth on originally not nutritionally sufficient bacteria L. plantarum. Among these crucial genes, we confirmed E. coli pdxH, and the downstream metabolite pyridoxal 5-P (PLP, Vitamin B6) as important nutritional factors for C. elegans postembryonic development. Transcriptome results suggest that bacterial pdxH affects host development by coordinating host metabolic processes and PLP binding. Additionally, the developmental arrest induced by the L. plantarum diet in worm does not depend on the activation of FoxO/DAF-16. Altogether, these results highlight the role of microbial metabolite PLP as a crucial cofactor to restore postembryonic development in C. elegans.
Collapse
Affiliation(s)
- Min Feng
- Department of Chemical Engineering, Texas A&M University, College Station, TX, USA
| | - Baizhen Gao
- Department of Chemical Engineering, Texas A&M University, College Station, TX, USA
| | - Daniela Ruiz
- Department of Chemical Engineering, Texas A&M University, College Station, TX, USA
| | - Luis Rene Garcia
- Department of Biology, Texas A&M University, College Station, TX, USA
| | - Qing Sun
- Department of Chemical Engineering, Texas A&M University, College Station, TX, USA.
| |
Collapse
|
2
|
Liu J, Murray JI. Mechanisms of lineage specification in Caenorhabditis elegans. Genetics 2023; 225:iyad174. [PMID: 37847877 DOI: 10.1093/genetics/iyad174] [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: 08/26/2023] [Accepted: 09/18/2023] [Indexed: 10/19/2023] Open
Abstract
The studies of cell fate and lineage specification are fundamental to our understanding of the development of multicellular organisms. Caenorhabditis elegans has been one of the premiere systems for studying cell fate specification mechanisms at single cell resolution, due to its transparent nature, the invariant cell lineage, and fixed number of somatic cells. We discuss the general themes and regulatory mechanisms that have emerged from these studies, with a focus on somatic lineages and cell fates. We next review the key factors and pathways that regulate the specification of discrete cells and lineages during embryogenesis and postembryonic development; we focus on transcription factors and include numerous lineage diagrams that depict the expression of key factors that specify embryonic founder cells and postembryonic blast cells, and the diverse somatic cell fates they generate. We end by discussing some future perspectives in cell and lineage specification.
Collapse
Affiliation(s)
- Jun Liu
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - John Isaac Murray
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| |
Collapse
|
3
|
Gruss MJ, O’Callaghan C, Donnellan M, Corsi AK. A Twist-Box domain of the C. elegans Twist homolog, HLH-8, plays a complex role in transcriptional regulation. Genetics 2023; 224:iyad066. [PMID: 37067863 PMCID: PMC10411555 DOI: 10.1093/genetics/iyad066] [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: 11/04/2022] [Revised: 11/04/2022] [Accepted: 03/21/2023] [Indexed: 04/18/2023] Open
Abstract
TWIST1 is a basic helix-loop-helix (bHLH) transcription factor in humans that functions in mesoderm differentiation. TWIST1 primarily regulates genes as a transcriptional repressor often through TWIST-Box domain-mediated protein-protein interactions. The TWIST-Box also can function as an activation domain requiring 3 conserved, equidistant amino acids (LXXXFXXXR). Autosomal dominant mutations in TWIST1, including 2 reported in these conserved amino acids (F187L and R191M), lead to craniofacial defects in Saethre-Chotzen syndrome (SCS). Caenorhabditis elegans has a single TWIST1 homolog, HLH-8, that functions in the differentiation of the muscles responsible for egg laying and defecation. Null alleles in hlh-8 lead to severely egg-laying defective and constipated animals due to defects in the corresponding muscles. TWIST1 and HLH-8 share sequence identity in their bHLH regions; however, the domain responsible for the transcriptional activity of HLH-8 is unknown. Sequence alignment suggests that HLH-8 has a TWIST-Box LXXXFXXXR motif; however, its function also is unknown. CRISPR/Cas9 genome editing was utilized to generate a domain deletion and several missense mutations, including those analogous to SCS patients, in the 3 conserved HLH-8 amino acids to investigate their functional role. The TWIST-Box alleles did not phenocopy hlh-8 null mutants. The strongest phenotype detected was a retentive (Ret) phenotype with late-stage embryos in the hermaphrodite uterus. Further, GFP reporters of HLH-8 downstream target genes (arg-1::gfp and egl-15::gfp) revealed tissue-specific, target-specific, and allele-specific defects. Overall, the TWIST-Box in HLH-8 is partially required for the protein's transcriptional activity, and the conserved amino acids contribute unequally to the domain's function.
Collapse
Affiliation(s)
- Michael J Gruss
- Department of Biology, The Catholic University of America, 620 Michigan Ave., NE, Washington, D.C. 20064USA
| | - Colleen O’Callaghan
- Department of Biology, The Catholic University of America, 620 Michigan Ave., NE, Washington, D.C. 20064USA
| | - Molly Donnellan
- Department of Biology, The Catholic University of America, 620 Michigan Ave., NE, Washington, D.C. 20064USA
| | - Ann K Corsi
- Department of Biology, The Catholic University of America, 620 Michigan Ave., NE, Washington, D.C. 20064USA
| |
Collapse
|
4
|
Bosch PJ, Peek SL, Smolikove S, Weiner JA. Akirin proteins in development and disease: critical roles and mechanisms of action. Cell Mol Life Sci 2020; 77:4237-4254. [PMID: 32361777 PMCID: PMC7606436 DOI: 10.1007/s00018-020-03531-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Revised: 04/05/2020] [Accepted: 04/15/2020] [Indexed: 12/15/2022]
Abstract
The Akirin genes, which encode small, nuclear proteins, were first characterized in 2008 in Drosophila and rodents. Early studies demonstrated important roles in immune responses and tumorigenesis, which subsequent work found to be highly conserved. More recently, a multiplicity of Akirin functions, and the associated molecular mechanisms involved, have been uncovered. Here, we comprehensively review what is known about invertebrate Akirin and its two vertebrate homologues Akirin1 and Akirin2, highlighting their role in regulating gene expression changes across a number of biological systems. We detail essential roles for Akirin family proteins in the development of the brain, limb, and muscle, in meiosis, and in tumorigenesis, emphasizing associated signaling pathways. We describe data supporting the hypothesis that Akirins act as a "bridge" between a variety of transcription factors and major chromatin remodeling complexes, and discuss several important questions remaining to be addressed. In little more than a decade, Akirin proteins have gone from being completely unknown to being increasingly recognized as evolutionarily conserved mediators of gene expression programs essential for the formation and function of animals.
Collapse
Affiliation(s)
- Peter J Bosch
- Department of Biology and Iowa Neuroscience Institute, University of Iowa, 143 Biology Building, Iowa City, IA, 52242, USA
| | - Stacey L Peek
- Interdisciplinary Graduate Program in Neuroscience, Department of Biology and Iowa Neuroscience Institute, University of Iowa, 143 Biology Building, Iowa City, IA, 52242, USA
| | - Sarit Smolikove
- Department of Biology, University of Iowa, 143 Biology Building, Iowa City, IA, 52242, USA
| | - Joshua A Weiner
- Department of Biology and Iowa Neuroscience Institute, University of Iowa, 143 Biology Building, Iowa City, IA, 52242, USA.
| |
Collapse
|
5
|
Akirin Is Required for Muscle Function and Acts Through the TGF-β Sma/Mab Signaling Pathway in Caenorhabditis elegans Development. G3-GENES GENOMES GENETICS 2020; 10:387-400. [PMID: 31767636 PMCID: PMC6945016 DOI: 10.1534/g3.119.400377] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Akirin, a conserved metazoan protein, functions in muscle development in flies and mice. However, this was only tested in the rodent and fly model systems. Akirin was shown to act with chromatin remodeling complexes in transcription and was established as a downstream target of the NFκB pathway. Here we show a role for Caenorhabditis elegans Akirin/AKIR-1 in the muscle and body length regulation through a different pathway. Akirin localizes to somatic tissues throughout the body of C. elegans, including muscle nuclei. In agreement with its role in other model systems, Akirin loss of function mutants exhibit defects in muscle development in the embryo, as well as defects in movement and maintenance of muscle integrity in the C. elegans adult. We also have determined that Akirin acts downstream of the TGF-β Sma/Mab signaling pathway in controlling body size. Moreover, we found that the loss of Akirin resulted in an increase in autophagy markers, similar to mutants in the TGF-β Sma/Mab signaling pathway. In contrast to what is known in rodent and fly models, C. elegans Akirin does not act with the SWI/SNF chromatin-remodeling complex, and is instead involved with the NuRD chromatin remodeling complex in both movement and regulation of body size. Our studies define a novel developmental role (body size) and a new pathway (TGF-β Sma/Mab) for Akirin function, and confirmed its evolutionarily conserved function in muscle development in a new organism.
Collapse
|
6
|
Kim S, Twigg SR, Scanlon VA, Chandra A, Hansen TJ, Alsubait A, Fenwick AL, McGowan SJ, Lord H, Lester T, Sweeney E, Weber A, Cox H, Wilkie AO, Golden A, Corsi AK. Localized TWIST1 and TWIST2 basic domain substitutions cause four distinct human diseases that can be modeled in Caenorhabditis elegans. Hum Mol Genet 2017; 26:2118-2132. [PMID: 28369379 PMCID: PMC5438873 DOI: 10.1093/hmg/ddx107] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Revised: 02/24/2017] [Accepted: 03/14/2017] [Indexed: 12/17/2022] Open
Abstract
Twist transcription factors, members of the basic helix-loop-helix family, play crucial roles in mesoderm development in all animals. Humans have two paralogous genes, TWIST1 and TWIST2, and mutations in each gene have been identified in specific craniofacial disorders. Here, we describe a new clinical entity, Sweeney-Cox syndrome, associated with distinct de novo amino acid substitutions (p.Glu117Val and p.Glu117Gly) at a highly conserved glutamic acid residue located in the basic DNA binding domain of TWIST1, in two subjects with frontonasal dysplasia and additional malformations. Although about one hundred different TWIST1 mutations have been reported in patients with the dominant haploinsufficiency Saethre-Chotzen syndrome (typically associated with craniosynostosis), substitutions uniquely affecting the Glu117 codon were not observed previously. Recently, subjects with Barber-Say and Ablepharon-Macrostomia syndromes were found to harbor heterozygous missense substitutions in the paralogous glutamic acid residue in TWIST2 (p.Glu75Ala, p.Glu75Gln and p.Glu75Lys). To study systematically the effects of these substitutions in individual cells of the developing mesoderm, we engineered all five disease-associated alleles into the equivalent Glu29 residue encoded by hlh-8, the single Twist homolog present in Caenorhabditis elegans. This allelic series revealed that different substitutions exhibit graded severity, in terms of both gene expression and cellular phenotype, which we incorporate into a model explaining the various human disease phenotypes. The genetic analysis favors a predominantly dominant-negative mechanism for the action of amino acid substitutions at this highly conserved glutamic acid residue and illustrates the value of systematic mutagenesis of C. elegans for focused investigation of human disease processes.
Collapse
Affiliation(s)
- Sharon Kim
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Stephen R.F. Twigg
- Clinical Genetics Group, MRC Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | - Victoria A. Scanlon
- Department of Biology, The Catholic University of America, Washington, DC 20064, USA
| | - Aditi Chandra
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Tyler J. Hansen
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Arwa Alsubait
- Department of Biology, The Catholic University of America, Washington, DC 20064, USA
| | - Aimee L. Fenwick
- Clinical Genetics Group, MRC Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | - Simon J. McGowan
- Computational Biology Research Group, MRC Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | - Helen Lord
- Oxford Medical Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Churchill Hospital, Oxford OX3 7LE, UK
| | - Tracy Lester
- Oxford Medical Genetics Laboratories, Oxford University Hospitals NHS Foundation Trust, Churchill Hospital, Oxford OX3 7LE, UK
| | - Elizabeth Sweeney
- Department of Clinical Genetics, Liverpool Women’s NHS Foundation Trust, Liverpool L8 7SS, UK
| | - Astrid Weber
- Department of Clinical Genetics, Liverpool Women’s NHS Foundation Trust, Liverpool L8 7SS, UK
| | - Helen Cox
- Clinical Genetics Unit, Birmingham Women’s NHS Foundation Trust, Birmingham Women’s Hospital, Birmingham B15 2TG, UK
| | - Andrew O.M. Wilkie
- Clinical Genetics Group, MRC Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK
| | - Andy Golden
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ann K. Corsi
- Department of Biology, The Catholic University of America, Washington, DC 20064, USA
| |
Collapse
|
7
|
Jacqueroud L, Bouard C, Richard G, Payen L, Devouassoux-Shisheboran M, Spicer DB, Caramel J, Collin G, Puisieux A, Tissier A, Ansieau S. The Heterodimeric TWIST1-E12 Complex Drives the Oncogenic Potential of TWIST1 in Human Mammary Epithelial Cells. Neoplasia 2017; 18:317-327. [PMID: 27237323 PMCID: PMC4887617 DOI: 10.1016/j.neo.2016.03.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 03/18/2016] [Accepted: 03/28/2016] [Indexed: 11/26/2022] Open
Abstract
The TWIST1 embryonic transcription factor displays biphasic functions during the course of carcinogenesis. It facilitates the escape of cells from oncogene-induced fail-safe programs (senescence, apoptosis) and their consequent neoplastic transformation. Additionally, it promotes the epithelial-to-mesenchymal transition and the initiation of the metastatic spread of cancer cells. Interestingly, cancer cells recurrently remain dependent on TWIST1 for their survival and/or proliferation, making TWIST1 their Achilles’ heel. TWIST1 has been reported to form either homodimeric or heterodimeric complexes mainly in association with the E bHLH class I proteins. These complexes display distinct, sometimes even antagonistic, functions during development and unequal prometastatic functions in prostate cancer cells. Using a tethered dimer strategy, we successively assessed the ability of TWIST1 dimers to cooperate with an activated version of RAS in human mammary epithelial cell transformation, to provide mice with the ability to spontaneously develop breast tumors, and lastly to maintain a senescence program at a latent state in several breast cancer cell lines. We demonstrate that the TWIST1-E12 complex, unlike the homodimer, is an oncogenic form of TWIST1 in mammary epithelial cells and that efficient binding of both partners is a prerequisite for its activity. The detection of the heterodimer in human premalignant lesions by a proximity ligation assay, at a stage preceding the initiation of the metastatic cascade, is coherent with such an oncogenic function. TWIST1-E protein heterodimeric complexes may thus constitute the main active forms of TWIST1 with regard to senescence inhibition over the time course of breast tumorigenesis.
Collapse
Affiliation(s)
- Laurent Jacqueroud
- Inserm UMR-S1052, Centre de Recherche en Cancérologie de Lyon, France; CNRS UMR5286, Centre de Recherche en Cancérologie de Lyon, France; LabEX DEVweCAN, Lyon, France; UNIV UMR1052, Lyon, France; Centre Léon Bérard, Lyon, France
| | - Charlotte Bouard
- Inserm UMR-S1052, Centre de Recherche en Cancérologie de Lyon, France; CNRS UMR5286, Centre de Recherche en Cancérologie de Lyon, France; LabEX DEVweCAN, Lyon, France; UNIV UMR1052, Lyon, France; Centre Léon Bérard, Lyon, France
| | - Geoffrey Richard
- Inserm UMR-S1052, Centre de Recherche en Cancérologie de Lyon, France; CNRS UMR5286, Centre de Recherche en Cancérologie de Lyon, France; LabEX DEVweCAN, Lyon, France; UNIV UMR1052, Lyon, France; Centre Léon Bérard, Lyon, France
| | - Léa Payen
- Inserm UMR-S1052, Centre de Recherche en Cancérologie de Lyon, France; CNRS UMR5286, Centre de Recherche en Cancérologie de Lyon, France; LabEX DEVweCAN, Lyon, France; UNIV UMR1052, Lyon, France; Centre Léon Bérard, Lyon, France; Université de Lyon 1, ISPB, Lyon, France; Hospices Civils de Lyon, Lyon, France
| | - Mojgan Devouassoux-Shisheboran
- Inserm UMR-S1052, Centre de Recherche en Cancérologie de Lyon, France; CNRS UMR5286, Centre de Recherche en Cancérologie de Lyon, France; LabEX DEVweCAN, Lyon, France; UNIV UMR1052, Lyon, France; Centre Léon Bérard, Lyon, France; Université de Lyon 1, ISPB, Lyon, France; Hospices Civils de Lyon, Lyon, France; Hôpital de la Croix-Rousse, Lyon, France
| | - Douglas B Spicer
- Center for Molecular Medicine, Main Medical Center Research Institute, Scarborough, ME, USA
| | - Julie Caramel
- Inserm UMR-S1052, Centre de Recherche en Cancérologie de Lyon, France; CNRS UMR5286, Centre de Recherche en Cancérologie de Lyon, France; LabEX DEVweCAN, Lyon, France; UNIV UMR1052, Lyon, France; Centre Léon Bérard, Lyon, France; Université de Lyon 1, ISPB, Lyon, France
| | - Guillaume Collin
- Inserm UMR-S1052, Centre de Recherche en Cancérologie de Lyon, France; CNRS UMR5286, Centre de Recherche en Cancérologie de Lyon, France; LabEX DEVweCAN, Lyon, France; UNIV UMR1052, Lyon, France; Centre Léon Bérard, Lyon, France
| | - Alain Puisieux
- Inserm UMR-S1052, Centre de Recherche en Cancérologie de Lyon, France; CNRS UMR5286, Centre de Recherche en Cancérologie de Lyon, France; LabEX DEVweCAN, Lyon, France; UNIV UMR1052, Lyon, France; Centre Léon Bérard, Lyon, France; Université de Lyon 1, ISPB, Lyon, France; Institut Universitaire de France, Paris, France
| | - Agnès Tissier
- Inserm UMR-S1052, Centre de Recherche en Cancérologie de Lyon, France; CNRS UMR5286, Centre de Recherche en Cancérologie de Lyon, France; LabEX DEVweCAN, Lyon, France; UNIV UMR1052, Lyon, France; Centre Léon Bérard, Lyon, France
| | - Stéphane Ansieau
- Inserm UMR-S1052, Centre de Recherche en Cancérologie de Lyon, France; CNRS UMR5286, Centre de Recherche en Cancérologie de Lyon, France; LabEX DEVweCAN, Lyon, France; UNIV UMR1052, Lyon, France; Centre Léon Bérard, Lyon, France.
| |
Collapse
|
8
|
Cram EJ. Mechanotransduction in C. elegans morphogenesis and tissue function. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2014; 126:281-316. [PMID: 25081623 DOI: 10.1016/b978-0-12-394624-9.00012-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Mechanobiology is an emerging field that investigates how living cells sense and respond to their physical surroundings. Recent interest in the field has been sparked by the finding that stem cells differentiate along different lineages based on the stiffness of the cell surroundings (Engler et al., 2006), and that metastatic behavior of cancer cells is strongly influenced by the mechanical properties of the surrounding tissue (Kumar and Weaver, 2009). Many questions remain about how cells convert mechanical information, such as viscosity, stiffness of the substrate, or stretch state of the cells, into the biochemical signals that control tissue function. Caenorhabditis elegans researchers are making significant contributions to the understanding of mechanotransduction in vivo. This review summarizes recent insights into the role of mechanical forces in morphogenesis and tissue function. Examples of mechanical regulation across length scales, from the single-celled zygote, to the intercellular coordination that enables cohesive tissue function, to the mechanical influences between tissues, are considered. The power of the C. elegans system as a gene discovery and in vivo quantitative bioimaging platform is enabling an important discoveries in this exciting field.
Collapse
Affiliation(s)
- Erin J Cram
- Department of Biology, Northeastern University, Boston, Massachusetts, USA
| |
Collapse
|
9
|
Hu D, Scott IC, Snider F, Geary-Joo C, Zhao X, Simmons DG, Cross JC. The basic helix-loop-helix transcription factor Hand1 regulates mouse development as a homodimer. Dev Biol 2013; 382:470-81. [PMID: 23911935 DOI: 10.1016/j.ydbio.2013.07.025] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Revised: 07/04/2013] [Accepted: 07/28/2013] [Indexed: 10/26/2022]
Abstract
Hand1 is a basic helix-loop-helix transcription factor that is essential for development of the placenta, yolk sac and heart during mouse development. While Hand1 is essential for trophoblast giant cell (TGC) differentiation, its potential heterodimer partners are not co-expressed in TGCs. To test the hypothesis that Hand1 functions as homodimer, we generated knock-in mice in which the Hand1 gene was altered to encode a tethered homodimer (TH). Some Hand1(TH/-) conceptuses in which the only form of Hand1 is Hand1(TH) are viable and fertile, indicating that homodimer Hand1 is sufficient for mouse survival. ~2/3 of Hand1(TH/-) and all Hand1(TH/TH) mice died in utero and displayed severe placental defects and variable cardial and cranial-facial abnormalities, indicating a dosage-dependent effect of Hand1(TH). Meanwhile, expression of the Hand1(TH) protein did not have negative effects on viability or fertility in all Hand1(TH/+) mice. These data imply that Hand1 homodimer plays a dominant role during development and its expression dosage is critical for survival, whereas Hand1 heterodimers can be either dispensable or play a regulatory role to modulate the activity of Hand1 homodimer in vivo.
Collapse
Affiliation(s)
- Dong Hu
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Calgary, Calgary, AB, Canada; Department of Comparative Biology and Experimental Medicine, Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada; Center for Stem Cell Application and Research, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
| | | | | | | | | | | | | |
Collapse
|