1
|
Juárez-Morales JL, Weierud F, England SJ, Demby C, Santos N, Grieb G, Mazan S, Lewis KE. Evolution of lbx spinal cord expression and function. Evol Dev 2021; 23:404-422. [PMID: 34411410 DOI: 10.1111/ede.12387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 06/04/2021] [Accepted: 06/21/2021] [Indexed: 11/29/2022]
Abstract
Ladybird homeobox (Lbx) transcription factors have crucial functions in muscle and nervous system development in many animals. Amniotes have two Lbx genes, but only Lbx1 is expressed in spinal cord. In contrast, teleosts have three lbx genes and we show here that zebrafish lbx1a, lbx1b, and lbx2 are expressed by distinct spinal cell types, and that lbx1a is expressed in dI4, dI5, and dI6 interneurons, as in amniotes. Our data examining lbx expression in Scyliorhinus canicula and Xenopus tropicalis suggest that the spinal interneuron expression of zebrafish lbx1a is ancestral, whereas lbx1b has acquired a new expression pattern in spinal cord progenitor cells. lbx2 spinal expression was probably acquired in the ray-finned lineage, as this gene is not expressed in the spinal cords of either amniotes or S. canicula. We also show that the spinal function of zebrafish lbx1a is conserved with mouse Lbx1. In zebrafish lbx1a mutants, there is a reduction in the number of inhibitory spinal interneurons and an increase in the number of excitatory spinal interneurons, similar to mouse Lbx1 mutants. Interestingly, the number of inhibitory spinal interneurons is also reduced in lbx1b mutants, although in this case the number of excitatory interneurons is not increased. lbx1a;lbx1b double mutants have a similar spinal interneuron phenotype to lbx1a single mutants. Taken together these data suggest that lbx1b and lbx1a may be required in succession for correct specification of dI4 and dI6 spinal interneurons, although only lbx1a is required for suppression of excitatory fates in these cells.
Collapse
Affiliation(s)
| | - Frida Weierud
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, UK
| | | | - Celia Demby
- Department of Biology, Syracuse University, Syracuse, New York, USA
| | - Nicole Santos
- Department of Biology, Syracuse University, Syracuse, New York, USA
| | - Ginny Grieb
- Department of Biology, Syracuse University, Syracuse, New York, USA
| | - Sylvie Mazan
- Biologie Intégrative des Organismes Marins, UMR 7232 CNRS, Observatoire Océanologique, Sorbonne Université, Banyuls-sur-Mer, France
| | | |
Collapse
|
2
|
Kusakabe R, Higuchi S, Tanaka M, Kadota M, Nishimura O, Kuratani S. Novel developmental bases for the evolution of hypobranchial muscles in vertebrates. BMC Biol 2020; 18:120. [PMID: 32907560 PMCID: PMC7488077 DOI: 10.1186/s12915-020-00851-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 08/18/2020] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Vertebrates are characterized by possession of hypobranchial muscles (HBMs). Cyclostomes, or modern jawless vertebrates, possess a rudimentary and superficial HBM lateral to the pharynx, whereas the HBM in jawed vertebrates is internalized and anteroposteriorly specified. Precursor cells of the HBM, marked by expression of Lbx1, originate from somites and undergo extensive migration before becoming innervated by the hypoglossal nerve. How the complex form of HBM arose in evolution is relevant to the establishment of the vertebrate body plan, but despite having long been assumed to be similar to that of limb muscles, modification of developmental mechanisms of HBM remains enigmatic. RESULTS Here we characterize the expression of Lbx genes in lamprey and hagfish (cyclostomes) and catshark (gnathostome; jawed vertebrates). We show that the expression patterns of the single cyclostome Lbx homologue, Lbx-A, do not resemble the somitic expression of mammalian Lbx1. Disruption of Lbx-A revealed that LjLbx-A is required for the formation of both HBM and body wall muscles, likely due to the insufficient extension of precursor cells rather than to hindered muscle differentiation. Both homologues of Lbx in the catshark were expressed in the somitic muscle primordia, unlike in amniotes. During catshark embryogenesis, Lbx2 is expressed in the caudal HBM as well as in the abdominal rectus muscle, similar to lamprey Lbx-A, whereas Lbx1 marks the rostral HBM and pectoral fin muscle. CONCLUSIONS We conclude that the vertebrate HBM primarily emerged as a specialized somatic muscle to cover the pharynx, and the anterior internalized HBM of the gnathostomes is likely a novelty added rostral to the cyclostome-like HBM, for which duplication and functionalization of Lbx genes would have been a prerequisite.
Collapse
Affiliation(s)
- Rie Kusakabe
- Laboratory for Evolutionary Morphology, RIKEN Center for Biosystems Dynamics Research (BDR), 2-2-3 Minatojima-minami, Chuo-ku, Kobe, Hyogo, 650-0047, Japan.
| | - Shinnosuke Higuchi
- Laboratory for Evolutionary Morphology, RIKEN Center for Biosystems Dynamics Research (BDR), 2-2-3 Minatojima-minami, Chuo-ku, Kobe, Hyogo, 650-0047, Japan
- Department of Biology, Graduate School of Science, Kobe University, Kobe, 657-8501, Japan
- Department of Molecular Biology and Biochemistry, Graduate School of Biomedical & Health Sciences, Hiroshima University, Hiroshima, 734-8553, Japan
| | - Masako Tanaka
- Laboratory for Evolutionary Morphology, RIKEN Center for Biosystems Dynamics Research (BDR), 2-2-3 Minatojima-minami, Chuo-ku, Kobe, Hyogo, 650-0047, Japan
| | - Mitsutaka Kadota
- Laboratory for Phyloinformatics, RIKEN Center for Biosystems Dynamics Research (BDR), Kobe, 650-0047, Japan
| | - Osamu Nishimura
- Laboratory for Phyloinformatics, RIKEN Center for Biosystems Dynamics Research (BDR), Kobe, 650-0047, Japan
| | - Shigeru Kuratani
- Laboratory for Evolutionary Morphology, RIKEN Center for Biosystems Dynamics Research (BDR), 2-2-3 Minatojima-minami, Chuo-ku, Kobe, Hyogo, 650-0047, Japan
- Evolutionary Morphology Laboratory, RIKEN Cluster for Pioneering Research (CPR), Kobe, 650-0047, Japan
| |
Collapse
|
3
|
Primary myogenesis in the sand lizard (Lacerta agilis) limb bud. Dev Genes Evol 2019; 229:147-159. [PMID: 31214772 PMCID: PMC6867991 DOI: 10.1007/s00427-019-00635-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Accepted: 06/02/2019] [Indexed: 11/23/2022]
Abstract
Our studies conducted on reptilian limb muscle development revealed, for the first time, early forelimb muscle differentiation at the morphological and molecular level. Sand lizard skeletal muscle differentiation in the early forelimb bud was investigated by light, confocal, and transmission electron microscopy as well as western blot. The early forelimb bud, filled with mesenchymal cells, is surrounded by monolayer epithelium cells. The immunocytochemical analysis revealed the presence of Pax3- and Lbx-positive cells in the vicinity of the ventro-lateral lip (VLL) of the dermomyotome, suggesting that VLL is the source of limb muscle progenitor cells. Furthermore, Pax3- and Lbx-positive cells were observed in the dorsal and ventral myogenic pools of the forelimb bud. Skeletal muscle development in the early limb bud is asynchronous, which is manifested by the presence of myogenic cells in different stages of differentiation: multinucleated myotubes with well-developed contractile apparatus, myoblasts, and mitotically active premyoblasts. The western blot analysis revealed the presence of MyoD and Myf5 proteins in all investigated developmental stages. The MyoD western blot analysis showed two bands corresponding to monomeric (mMyoD) and dimeric (dMyoD) fractions. Two separate bands were also detected in the case of Myf5. The observed bands were related to non-phosphorylated (Myf5) and phosphorylated (pMyf5) fractions of Myf5. Our investigations on sand lizard forelimb myogenesis showed that the pattern of muscle differentiation in the early forelimb bud shares many features with rodents and chicks.
Collapse
|
4
|
Wang J, Luo J, Chen Q, Wang X, He J, Zhang W, Yin Z, Zheng F, Pan H, Li T, Lou Q, Wang B. Identification of LBX2 as a novel causal gene of atrial septal defect. Int J Cardiol 2018; 265:188-194. [PMID: 29669692 DOI: 10.1016/j.ijcard.2018.04.038] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 04/03/2018] [Accepted: 04/09/2018] [Indexed: 11/26/2022]
Abstract
BACKGROUND Atrial septal defect (ASD) is one of the most common cardiac malformations worldwide. Several genes have been identified so far, which can merely explain small proportion of all the cases, therefore, it is anticipated that there are additional genes causing ASD. The aims of this study were to identify the causal gene of ostium secundum atrial septal defect (ASDII) in a Chinese family. METHODS Whole exome sequencing was performed in three affected members and one control in the ASDII family. We screened mutations of LBX2 in 300 unrelated ASD patients and validated in 400 normal controls by Sanger sequencing. LBX2 knockout zebrafish was generated by CRISPR/Cas9 to detect whether lbx2 deficiency influenced cardiac development. RESULTS A rare missense mutation in LBX2 (c.A403G: p.K135E) was identified as the pathogenic cause of ASD. Subsequent mutation screening revealed two missense variants in 3 of 300 sporadic patients. We observed expanded size of atrium and ventricle in LBX2 knockout zebrafish through hematoxylin-eosin staining, more incompact distribution of cardiac myocytes was also discovered in homozygote compared with in wildtype. Furthermore, we performed in situ hybridization of crip2 gene to trace the cardiac neural crest cells in the embryo stage and found that the migration of neural crest cells was obviously delayed in the homozygotes. CONCLUSIONS We identified LBX2 for the first time as a pathogenic gene of ASDII. LBX2 deficiency may cause abnormal development of heart through influencing the migration of neural crest cells and affect the process of cardiac septation.
Collapse
Affiliation(s)
- Jing Wang
- Department of Medical Genetics and Developmental Biology, School of Basic Medical Sciences, Capital Medical University, Beijing 100069, China
| | - Jing Luo
- Center for Gene Diagnosis, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, China
| | - Qiuhong Chen
- Cardiovascular Center, Qinghai High Altitude Medical Research Institute, Xining 810012, China
| | - Xi Wang
- Center for Genetics, National Research Institute for Family Planning, Beijing 100081, China
| | - Jiangyan He
- Key Laboratory of Aquatic Biodiversity and Conservation of the Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China
| | - Wei Zhang
- Center for Genetics, National Research Institute for Family Planning, Beijing 100081, China
| | - Zhan Yin
- Key Laboratory of Aquatic Biodiversity and Conservation of the Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China
| | - Fang Zheng
- Center for Gene Diagnosis, Zhongnan Hospital, Wuhan University, Wuhan, Hubei 430071, China
| | - Hong Pan
- Center for Genetics, National Research Institute for Family Planning, Beijing 100081, China
| | - Tengyan Li
- Center for Genetics, National Research Institute for Family Planning, Beijing 100081, China
| | - Qiyong Lou
- Key Laboratory of Aquatic Biodiversity and Conservation of the Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, Hubei 430072, China.
| | - Binbin Wang
- Center for Genetics, National Research Institute for Family Planning, Beijing 100081, China.
| |
Collapse
|
5
|
Migratory appendicular muscles precursor cells in the common ancestor to all vertebrates. Nat Ecol Evol 2017; 1:1731-1736. [DOI: 10.1038/s41559-017-0330-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2016] [Accepted: 08/30/2017] [Indexed: 11/08/2022]
|
6
|
Zhao Y, Gao P, Li W, Zhang Y, Xu K, Guo X, Li B, Cao G. Study on the Developmental Expression ofLbx1Gene inLongissimus Dorsiof Mashen and Large White Pigs. ITALIAN JOURNAL OF ANIMAL SCIENCE 2016. [DOI: 10.4081/ijas.2015.3720] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
7
|
Wotton KR, Schubert FR, Dietrich S. Hypaxial muscle: controversial classification and controversial data? Results Probl Cell Differ 2015; 56:25-48. [PMID: 25344665 DOI: 10.1007/978-3-662-44608-9_2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Hypaxial muscle is the anatomical term commonly used when referring to all the ventrally located musculature in the body of vertebrates, including muscles of the body wall and the limbs. Yet these muscles had very humble beginnings when vertebrates evolved from their chordate ancestors, and complex anatomical changes and changes in underlying gene regulatory networks occurred. This review summarises the current knowledge and controversies regarding the development and evolution of hypaxial muscles.
Collapse
Affiliation(s)
- Karl R Wotton
- EMBL/CRG Systems Biology Research Unit, Centre for Genomic Regulation (CRG), Dr. Aiguader 88, 08003, Barcelona, Spain
| | | | | |
Collapse
|
8
|
Qin C, Han Z, Qian J, Bao M, Li P, Ju X, Zhang S, Zhang L, Li S, Cao Q, Lu Q, Li J, Shao P, Meng X, Zhang W, Yin C. Expression pattern of long non-coding RNAs in renal cell carcinoma revealed by microarray. PLoS One 2014; 9:e99372. [PMID: 24905231 PMCID: PMC4048223 DOI: 10.1371/journal.pone.0099372] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 05/14/2014] [Indexed: 01/23/2023] Open
Abstract
Background Recent large-scale transcriptome analyses have found large numbers of transcripts, including that of long non-coding RNAs (lncRNAs), which are aberrant in various diseases, especially cancers. However, it is not clear whether lncRNAs are involved specifically in renal cell carcinoma (RCC). We investigated the expression patterns of lncRNAs in five RCC tumor samples (T) relative to those of matched adjacent non-tumor tissues (N) via microarray. Methods A microarray with 33,045 lncRNA probes and 30,215 mRNA probes was used to identify deregulated lncRNAs in five RCC patients. Furthermore, we confirmed the relative expression levels of AK096725 and ENST00000453068 in 70 paired samples by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Results The lncRNA microarray revealed 27,279 lncRNAs in RCC samples, of which 480 were significantly upregulated (P<0.05; T/N>1.5) and 417 were significantly downregulated (P<0.05; N/T>1.5) compared with the matched non-tumor samples. In addition, 19,995 mRNAs were detected, of which 458 were significantly upregulated (P<0.05; T/N>1.5) and 413 were significantly downregulated (P<0.05; N/T>1.5). The expression level changes of AK096725 (P = 0.043) and ENST00000453068 (P<0.001) in 70 paired samples were in accord with the microarray data. Conclusions The study uncovered expression patterns of lncRNAs in 5 RCC patients, as well as a number of aberrant lncRNAs and mRNAs in tumor samples compared with the non-tumor tissues. The revelation of an association between AK096725 expression and RCC is especially noteworthy. These findings may help to find new biomarkers in RCC.
Collapse
MESH Headings
- Biomarkers, Tumor/biosynthesis
- Biomarkers, Tumor/genetics
- Carcinoma, Renal Cell/genetics
- Carcinoma, Renal Cell/metabolism
- Carcinoma, Renal Cell/pathology
- Female
- Gene Expression Regulation, Neoplastic
- Humans
- Kidney Neoplasms/genetics
- Kidney Neoplasms/metabolism
- Kidney Neoplasms/pathology
- Male
- RNA, Long Noncoding/biosynthesis
- RNA, Long Noncoding/genetics
- RNA, Neoplasm/biosynthesis
- RNA, Neoplasm/genetics
Collapse
Affiliation(s)
- Chao Qin
- Department of Urology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Zhijian Han
- Department of Urology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Jian Qian
- Department of Urology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Meiling Bao
- Department of Urology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Pu Li
- Department of Urology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Xiaobing Ju
- Department of Urology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Shaobo Zhang
- Department of Urology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Lei Zhang
- Department of Urology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Shuang Li
- Department of Urology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Qiang Cao
- Department of Urology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Qiang Lu
- Department of Urology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Jie Li
- Department of Urology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Pengfei Shao
- Department of Urology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Xiaoxin Meng
- Department of Urology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| | - Wei Zhang
- Department of Urology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, China
- * E-mail:
| | - Changjun Yin
- Department of Urology, the First Affiliated Hospital of Nanjing Medical University, Nanjing, China
| |
Collapse
|
9
|
Role of zebrafish lbx2 in embryonic lateral line development. PLoS One 2011; 6:e29515. [PMID: 22216300 PMCID: PMC3245281 DOI: 10.1371/journal.pone.0029515] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2011] [Accepted: 11/29/2011] [Indexed: 11/19/2022] Open
Abstract
Background The zebrafish ladybird homeobox homologous gene 2 (lbx2) has been suggested to play a key role in the regulation of hypaxial myogenic precursor cell migration. Unlike their lbx counterparts in mammals, the function of teleost lbx genes beyond myogenesis during embryonic development remains unexplored. Principal Findings Abrogation of lbx2 function using a specific independent morpholino oligonucleotide (MO) or truncated lbx2 mRNA with an engrailed domain deletion (lbx2eh-) resulted in defective formation of the zebrafish posterior lateral line (PLL). Migration of the PLL primordium was altered and accompanied by increased cell death in the primordium of lbx2-MO-injected embryos. A decreased number of muscle pioneer cells and impaired expression pattern of sdf1a in the horizontal myoseptum was observed in lbx2 morphants. Significance Injection of lbx2 MO or lbx2eh- mRNA resulted in defective PPL formation and altered sdf1a expression, confirming an important function for lbx2 in sdf1a-dependent migration. In addition, the disassociation of PPL nerve extension with PLL primordial migration in some lbx2 morphants suggests that pathfinding of the PLL primordium and the lateral line nerve may be regulated independently.
Collapse
|
10
|
Lukowski CM, Drummond DL, Waskiewicz AJ. Pbx-dependent regulation of lbx gene expression in developing zebrafish embryos. Genome 2011; 54:973-85. [PMID: 22077099 DOI: 10.1139/g11-061] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Ladybird (Lbx) homeodomain transcription factors function in neural and muscle development--roles conserved from Drosophila to vertebrates. Lbx expression in mice specifies neural cell types, including dorsally located interneurons and association neurons, within the neural tube. Little, however, is known about the regulation of vertebrate lbx family genes. Here we describe the expression pattern of three zebrafish ladybird genes via mRNA in situ hybridization. Zebrafish lbx genes are expressed in distinct but overlapping regions within the developing neural tube, with strong expression within the hindbrain and spinal cord. The Hox family of transcription factors, in cooperation with cofactors such as Pbx and Meis, regulate hindbrain segmentation during embryogenesis. We have identified a novel regulatory interaction in which lbx1 genes are strongly downregulated in Pbx-depleted embryos. Further, we have produced a transgenic zebrafish line expressing dTomato and EGFP under the control of an lbx1b enhancer--a useful tool to acertain neuron location, migration, and morphology. Using this transgenic strain, we have identified a minimal neural lbx1b enhancer that contains key regulatory elements for expression of this transcription factor.
Collapse
Affiliation(s)
- Chris M Lukowski
- Department of Biological Sciences, University of Alberta, CW 405, Biological Sciences Building, Edmonton, AB T6G2E9, Canada
| | | | | |
Collapse
|
11
|
Moisan V, Robert NM, Tremblay JJ. Expression of ladybird-like homeobox 2 (LBX2) during ovarian development and folliculogenesis in the mouse. J Mol Histol 2010; 41:289-94. [PMID: 20820887 DOI: 10.1007/s10735-010-9291-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2009] [Accepted: 08/26/2010] [Indexed: 01/16/2023]
Abstract
The Ladybird-like homeobox gene 2 (Lbx2) belongs to the homeodomain-containing family of transcription factor that are known to play crucial role in various developmental processes. During early mouse embryogenesis, Lbx2 was shown to be expressed in the developing eye, brain and urogenital system. Although Lbx2 was detected in the testis and epididymis throughout development, no data was available regarding its expression in the female gonad. Here we have determined Lbx2 expression throughout mouse ovarian development by in situ hybridization. In contrast to the strong expression in the male fetal gonad, no Lbx2 signal could be detected in the fetal ovary. Soon after birth, however, Lbx2 expression was detected at different levels in various ovarian compartments (oocyte, granulosa cells, theca cells) where its expression was highly dynamic depending on the stage of follicular maturation. Our data would be consistent with a role for LBX2 in ovarian maturation and folliculogenesis.
Collapse
Affiliation(s)
- Vanessa Moisan
- Reproduction, Perinatal and Child Health, CHUQ Research Centre, CHUL Room T1-49, 2705 Laurier Blvd, Quebec City, QC G1V 4G2, Canada.
| | | | | |
Collapse
|
12
|
Wotton KR, Weierud FK, Juárez-Morales JL, Alvares LE, Dietrich S, Lewis KE. Conservation of gene linkage in dispersed vertebrate NK homeobox clusters. Dev Genes Evol 2010; 219:481-96. [PMID: 20112453 DOI: 10.1007/s00427-009-0311-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Nk homeobox genes are important regulators of many different developmental processes including muscle, heart, central nervous system and sensory organ development. They are thought to have arisen as part of the ANTP megacluster, which also gave rise to Hox and ParaHox genes, and at least some NK genes remain tightly linked in all animals examined so far. The protostome-deuterostome ancestor probably contained a cluster of nine Nk genes: (Msx)-(Nk4/tinman)-(Nk3/bagpipe)-(Lbx/ladybird)-(Tlx/c15)-(Nk7)-(Nk6/hgtx)-(Nk1/slouch)-(Nk5/Hmx). Of these genes, only NKX2.6-NKX3.1, LBX1-TLX1 and LBX2-TLX2 remain tightly linked in humans. However, it is currently unclear whether this is unique to the human genome as we do not know which of these Nk genes are clustered in other vertebrates. This makes it difficult to assess whether the remaining linkages are due to selective pressures or because chance rearrangements have "missed" certain genes. In this paper, we identify all of the paralogs of these ancestrally clustered NK genes in several distinct vertebrates. We demonstrate that tight linkages of Lbx1-Tlx1, Lbx2-Tlx2 and Nkx3.1-Nkx2.6 have been widely maintained in both the ray-finned and lobe-finned fish lineages. Moreover, the recently duplicated Hmx2-Hmx3 genes are also tightly linked. Finally, we show that Lbx1-Tlx1 and Hmx2-Hmx3 are flanked by highly conserved noncoding elements, suggesting that shared regulatory regions may have resulted in evolutionary pressure to maintain these linkages. Consistent with this, these pairs of genes have overlapping expression domains. In contrast, Lbx2-Tlx2 and Nkx3.1-Nkx2.6, which do not seem to be coexpressed, are also not associated with conserved noncoding sequences, suggesting that an alternative mechanism may be responsible for the continued clustering of these genes.
Collapse
Affiliation(s)
- Karl R Wotton
- Department of Craniofacial Development, King's College London, Floor 27 Guy's Tower, Guy's Hospital, London Bridge, London, SE1 9RT, UK
| | | | | | | | | | | |
Collapse
|
13
|
Ochi H, Westerfield M. Lbx2 regulates formation of myofibrils. BMC DEVELOPMENTAL BIOLOGY 2009; 9:13. [PMID: 19216761 PMCID: PMC2656488 DOI: 10.1186/1471-213x-9-13] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2008] [Accepted: 02/12/2009] [Indexed: 11/10/2022]
Abstract
BACKGROUND Skeletal muscle differentiation requires assembly of contractile proteins into organized myofibrils. The Drosophila ladybird homeobox gene (lad) functions in founder cells of the segmental border muscle to promote myoblast fusion and muscle shaping. Tetrapods have two homologous genes (Lbx). Lbx1 functions in migration and/or proliferation of hypaxial myoblasts, whereas the function of Lbx2 is poorly understood. RESULTS To elucidate the role of Lbx in vertebrate myogenesis, we examined Lbx function in zebrafish. Zebrafish lbx2 transcripts appear in newly formed paraxial mesoderm and become restricted to adaxial cells, precursors of slow muscle. Slow muscles lose lbx2 expression as they differentiate, while a subset of differentiating fast muscle cells transiently expresses lbx2. Fin and hyoid muscle express lbx2 later. In contrast, lbx1b expression first appears lateral to the somites at late segmentation stages and is later restricted to fin muscle. Morpholino knockdown of Lbx1b and Lbx2 suppresses hypaxial muscle development. Moreover, knockdown of Lbx2 results in malformation of muscle fibers and reduced fusion of fast precursors, although no obvious effects on induction or specification are observed. Expression of myofilament genes, including actin and myosin, requires the engrailed repressor domain of Lbx2. CONCLUSION Our results elucidate a new function of Lbx2 as a regulator of myofibril formation.
Collapse
Affiliation(s)
- Haruki Ochi
- Institute of Neuroscience, University of Oregon, Eugene, OR 97403-1254, USA
| | - Monte Westerfield
- Developmental Genomics Research Group, Nara Institute of Science and Technology, 8916-5 Takayama Ikoma Nara 630-0192, Japan
| |
Collapse
|
14
|
Wotton KR, Weierud FK, Dietrich S, Lewis KE. Comparative genomics of Lbx loci reveals conservation of identical Lbx ohnologs in bony vertebrates. BMC Evol Biol 2008; 8:171. [PMID: 18541024 PMCID: PMC2446394 DOI: 10.1186/1471-2148-8-171] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2008] [Accepted: 06/09/2008] [Indexed: 01/07/2023] Open
Abstract
Background Lbx/ladybird genes originated as part of the metazoan cluster of Nk homeobox genes. In all animals investigated so far, both the protostome genes and the vertebrate Lbx1 genes were found to play crucial roles in neural and muscle development. Recently however, additional Lbx genes with divergent expression patterns were discovered in amniotes. Early in the evolution of vertebrates, two rounds of whole genome duplication are thought to have occurred, during which 4 Lbx genes were generated. Which of these genes were maintained in extant vertebrates, and how these genes and their functions evolved, is not known. Results Here we searched vertebrate genomes for Lbx genes and discovered novel members of this gene family. We also identified signature genes linked to particular Lbx loci and traced the remnants of 4 Lbx paralogons (two of which retain Lbx genes) in amniotes. In teleosts, that have undergone an additional genome duplication, 8 Lbx paralogons (three of which retain Lbx genes) were found. Phylogenetic analyses of Lbx and Lbx-associated genes show that in extant, bony vertebrates only Lbx1- and Lbx2-type genes are maintained. Of these, some Lbx2 sequences evolved faster and were probably subject to neofunctionalisation, while Lbx1 genes may have retained more features of the ancestral Lbx gene. Genes at Lbx1 and former Lbx4 loci are more closely related, as are genes at Lbx2 and former Lbx3 loci. This suggests that during the second vertebrate genome duplication, Lbx1/4 and Lbx2/3 paralogons were generated from the duplicated Lbx loci created during the first duplication event. Conclusion Our study establishes for the first time the evolutionary history of Lbx genes in bony vertebrates, including the order of gene duplication events, gene loss and phylogenetic relationships. Moreover, we identified genetic hallmarks for each of the Lbx paralogons that can be used to trace Lbx genes as other vertebrate genomes become available. Significantly, we show that bony vertebrates only retained copies of Lbx1 and Lbx2 genes, with some Lbx2 genes being highly divergent. Thus, we have established a base on which the evolution of Lbx gene function in vertebrate development can be evaluated.
Collapse
Affiliation(s)
- Karl R Wotton
- King's College London, Department of Craniofacial Development, Floor 27 Guy's Tower, Guy's Hospital, London Bridge, London, SE1 9RT, UK.
| | | | | | | |
Collapse
|
15
|
Moisan V, Bomgardner D, Tremblay JJ. Expression of the Ladybird-like homeobox 2 transcription factor in the developing mouse testis and epididymis. BMC DEVELOPMENTAL BIOLOGY 2008; 8:22. [PMID: 18304314 PMCID: PMC2277406 DOI: 10.1186/1471-213x-8-22] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/15/2007] [Accepted: 02/27/2008] [Indexed: 02/04/2023]
Abstract
BACKGROUND Homeoproteins are a class of transcription factors that are well-known regulators of organogenesis and cell differentiation in numerous tissues, including the male reproductive system. Indeed, a handful of homeoproteins have so far been identified in the testis and epididymis where a few were shown to play important developmental roles. Through a degenerate PCR approach aimed at identifying novel homeoproteins expressed in the male reproductive system, we have detected several homeoproteins most of which had never been described before in this tissue. One of these homeoproteins is Ladybird-like homeobox 2 (Lbx2), a homeobox factor mostly known to be expressed in the nervous system. RESULTS To better define the expression profile of Lbx2 in the male reproductive system, we have performed in situ hybridization throughout testicular and epididymal development and into adulthood. Lbx2 expression was also confirmed by real time RT-PCR in those tissues and in several testicular and epididymal cell lines. In the epididymis, a highly segmented tissue, Lbx2 shows a regionalized expression profile, being more expressed in proximal segments of the caput epididymis than any other segment. In the testis, we found that Lbx2 is constitutively expressed at high levels in Sertoli cells. In interstitial cells, Lbx2 is weakly expressed during fetal and early postnatal life, highly expressed around P32-P36, and absent in adult animals. Finally, Lbx2 can also be detected in a population of germ cells in adults. CONCLUSION Altogether, our data suggest that the homeoprotein Lbx2 might be involved in the regulation of male reproductive system development and cell differentiation as well as in male epididymal segmentation.
Collapse
Affiliation(s)
- Vanessa Moisan
- Ontogeny-Reproduction Research Unit, CHUQ Research Centre (CHUL), Québec City, Québec, Canada.
| | | | | |
Collapse
|
16
|
Wei K, Chen J, Akrami K, Sekhon R, Chen F. Generation of mice deficient for Lbx2, a gene expressed in the urogenital system, nervous system, and Pax3 dependent tissues. Genesis 2007; 45:361-8. [PMID: 17492753 DOI: 10.1002/dvg.20302] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Lbx2 is a member of the ladybird family of homeobox genes. The first murine ortholog identified, Lbx1, is required for hypaxial musculature and dorsal spinal cord neuron development. The second murine ortholog, Lbx2, is expressed in the developing urogenital and nervous systems. To elucidate the function of Lbx2, we generated a gene-targeted allele of Lbx2 in mice. Lbx2 deficiency did not impair mouse development, and Lbx2 null mice appeared healthy and fertile. Replacement of Lbx2 by the lacZ gene provides a valuable histological marker for Lbx2-expressing cells. Given the important role of Pax3 in neural crest, we intercrossed our Lbx2 deficient mice with Splotch Pax3 mutant mice to determine if Pax3 affects Lbx2 expression. There was reduced Lbx2 expression in dorsal root ganglia and cranial nerve ganglia with Pax3 deficiency, but not in the genital tubercle. This suggested that Pax3 is required for Lbx2 expression in affected neural crest-derived tissues.
Collapse
Affiliation(s)
- Ke Wei
- Cardiovascular Research Laboratory, Division of Cardiology, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, California, USA
| | | | | | | | | |
Collapse
|
17
|
Kanamoto T, Terada K, Yoshikawa H, Furukawa T. Cloning and expression pattern of lbx3, a novel chick homeobox gene. Gene Expr Patterns 2005; 6:241-6. [PMID: 16378763 DOI: 10.1016/j.modgep.2005.08.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2005] [Revised: 08/19/2005] [Accepted: 08/23/2005] [Indexed: 01/14/2023]
Abstract
The Drosophila melanogaster genes, ladybird early (lbe) and ladybird late (lbl), encode transcriptional regulators, which play an important role in neurogenesis, myogenesis and cardiogenesis. Here, we report an isolation of a novel ladybird family homeobox gene (lbx3) and its expression during chick development. The open reading frame of lbx3 encodes a predicted protein of 213 amino acids including a homeodomain, a PST motif and a nuclear localization signal. The homeodomain of lbx3 protein has 80% identities with the chick and mouse lbx1 homeodomains, and 75% identity with the mouse lbx2 homeodomain. Both lbx1 and lbx3 are expressed in prospective hypaxial myoblasts at cervical and limb level. In addition, lbx3 transcripts are detected in the medial dermomyotomal lips of somites of all axial levels at stage 23, but not detected in the neural tube.
Collapse
MESH Headings
- Amino Acid Sequence
- Animals
- Base Sequence
- Chick Embryo
- Cloning, Molecular
- Conserved Sequence
- DNA, Complementary/genetics
- DNA, Complementary/isolation & purification
- Gene Expression Regulation, Developmental
- Gene Library
- Genes, Homeobox
- Homeodomain Proteins/chemistry
- Homeodomain Proteins/genetics
- In Situ Hybridization
- Molecular Sequence Data
- Nuclear Localization Signals/chemistry
- Open Reading Frames
- Phylogeny
- Protein Structure, Secondary
- Protein Structure, Tertiary
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Sequence Homology, Nucleic Acid
- Somites/metabolism
- Threonine/chemistry
Collapse
Affiliation(s)
- Takashi Kanamoto
- Osaka Bioscience Institute, 4th Department, 6-2-4 Furuedai, Suita, Osaka 565-0874, Japan
| | | | | | | |
Collapse
|
18
|
Abstract
The primary endocrine organs responsible for steroid hormone biosynthesis--the adrenal cortex and gonads--are derived from the urogenital ridge. Several recent discoveries in human and mouse genetics have begun to unravel the complex genetic cascade that dictates adrenocortical cell lineage, proliferation and differentiation. The factors that regulate adrenocortical organogenesis and the maintenance of growth promote or block a cascade of transcription factors that differentially coordinate the proliferation and differentiation of the gland. Here, we outline the developmental milestones of the adrenal cortex with recent contributions to the field, focusing on factors that have been shown to play a role in vivo in humans and mice.
Collapse
Affiliation(s)
- Catherine E Keegan
- Dept Pediatrics, Division of Genetics, University of Michigan Medical School, 5552 MSRB II, 1150 West Medical Center Drive, Ann Arbor, MI 48109-0678, USA
| | | |
Collapse
|
19
|
Chen F, Collin GB, Liu KC, Beier DR, Eccles M, Nishina PM, Moshang T, Epstein JA. Characterization of the murine Lbx2 promoter, identification of the human homologue, and evaluation as a candidate for Alström syndrome. Genomics 2001; 74:219-27. [PMID: 11386758 DOI: 10.1006/geno.2001.6539] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The murine Lbx2 gene is a member of the ladybird family of homeobox genes, which is expressed in the developing urogenital system, eye, and brain. Using transgenic mice, we demonstrate that 9 kb of the 5' flanking region of mouse Lbx2 is able to direct expression of a reporter gene in a tissue-specific manner recapitulating the endogenous expression pattern. This regulatory region provides a novel reagent allowing for transgenic expression in the developing urogenital ridge. In addition, we describe the identification of the human homologue, LBX2. Comparison of the human LBX2 and mouse Lbx2 sequences upstream of the coding regions reveals sequence conservation suggesting conserved regulatory regions. Both the human LBX2 and the mouse Lbx2 genes have similar genomic structures and are composed of two exons separated by an intron. We mapped the mouse Lbx2 gene to 35 cM on chromosome 6 and the human LBX2 gene to a homologous region of chromosome 2p13. This is a candidate region for several inherited disorders, including Alström syndrome, a disorder that includes ocular, urogenital, and renal abnormalities. Given the expression pattern of Lbx2, the chromosomal location in humans, and the potential function of mammalian ladybird genes, we have begun to analyze patients with ocular disorders and those with Alström syndrome for mutations in LBX2. Although polymorphisms were identified, our results indicate that mutations in the coding region of LBX2 do not account for Alström syndrome in the six kindreds analyzed.
Collapse
Affiliation(s)
- F Chen
- Cardiology Division, Department of Medicine, University of Pennsylvania Health System, Philadelphia, Pennsylvania 19104, USA
| | | | | | | | | | | | | | | |
Collapse
|
20
|
Kozmik Z, Holland LZ, Schubert M, Lacalli TC, Kreslova J, Vlcek C, Holland ND. Characterization of Amphioxus AmphiVent, an evolutionarily conserved marker for chordate ventral mesoderm. Genesis 2001; 29:172-9. [PMID: 11309850 DOI: 10.1002/gene.1021] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Structure and developmental expression are described for amphioxus AmphiVent, a homolog of vertebrate Vent genes. In amphioxus, AmphiVent-expressing ventral mesoderm arises at midneurula by outgrowth from the paraxial mesoderm, but in vertebrates, Vent-expressing ventral mesoderm originates earlier, at the gastrula stage. In other embryonic tissues (nascent paraxial mesoderm, neural plate, endoderm, and tailbud), AmphiVent and its vertebrate homologs are expressed in similar spatiotemporal domains, indicating conservation of many Vent gene functions during chordate evolution. The ventral mesoderm evidently develops precociously in vertebrates because their relatively large embryos probably require an early and extensive deployment of the mesoderm-derived circulatory system. The vertebrate ventral mesoderm, in spite of its strikingly early advent, still resembles the nascent ventral mesoderm of amphioxus in expressing Vent homologs. This coincidence may indicate that Vent homologs in vertebrates and amphioxus play comparable roles in ventral mesoderm specification.
Collapse
Affiliation(s)
- Z Kozmik
- Institute for Molecular Genetics, Academy of Science of the Czech Republic, Prague
| | | | | | | | | | | | | |
Collapse
|
21
|
Abstract
Although genes involved in common developmental programs are usually scattered throughout the metazoan genome, there are some important examples of functionally interconnected regulatory genes that display close physical linkage. In particular the homeotic genes, which determine the identities of body parts, are clustered in the Hox complexes and clustering is thought to be crucial for the proper execution of their developmental programs. Here we describe the organization and functional properties of a more recently identified cluster of six homeobox genes at 93DE on the third chromosome of Drosophila. These genes, which include tinman, bagpipe, ladybird early, ladybird late, C15, and slouch, all participate in mesodermal patterning and differentiation programs and show multiple regulatory interactions among each other. We propose that their clustering, through unknown mechanisms, is functionally significant and discuss the similarities and differences between the 93DE homeobox gene cluster and the Hox complexes.
Collapse
Affiliation(s)
- K Jagla
- INSERM U.384, Clermont Ferrand Cedex, France
| | | | | |
Collapse
|
22
|
Epstein JA, Li J, Lang D, Chen F, Brown CB, Jin F, Lu MM, Thomas M, Liu E, Wessels A, Lo CW. Migration of cardiac neural crest cells in Splotch embryos. Development 2000; 127:1869-78. [PMID: 10751175 DOI: 10.1242/dev.127.9.1869] [Citation(s) in RCA: 161] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Pax3 encodes a transcription factor expressed during mid-gestation in the region of the dorsal neural tube that gives rise to migrating neural crest populations. In the absence of Pax3, both humans and mice develop with neural crest defects. Homozygous Splotch embryos that lack Pax3 die by embryonic day 13.5 with cardiac defects that resemble those induced by neural crest ablation in chick models. This has led to the hypothesis that Pax3 is required for cardiac neural crest migration. However, cardiac derivatives of Pax3-expressing precursor cells have not been previously defined, and Pax3-expressing cells within the heart have not been well demonstrated. Hence, the precise role of Pax3 during cardiac development remains unclear. Here, we use a Cre-lox method to fate map Pax3-expressing neural crest precursors to the cardiac outflow tract. We show that although Pax3 itself is extinguished prior to neural crest populating the heart, derivatives of these precursors contribute to the aorticopulmonary septum. We further show that neural crest cells are found in the outflow tract of Splotch embryos, albeit in reduced numbers. This indicates that contrary to prior reports, Pax3 is not required for cardiac neural crest migration. Using a neural tube explant culture assay, we demonstrate that neural crest cells from Splotch embryos show normal rates of proliferation but altered migratory characteristics. These studies suggest that Pax3 is required for fine tuning the migratory behavior of the cardiac neural crest cells while it is not essential for neural crest migration.
Collapse
Affiliation(s)
- J A Epstein
- Cardiovascular Division, Department of Medicine and the Department of Cell and Molecular Biology, University of Pennsylvania Medical School, Philadelphia, PA 19104, USA.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|