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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.
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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
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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.
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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.
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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.
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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.
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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.
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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
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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.
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Affiliation(s)
- Vanessa Moisan
- Ontogeny-Reproduction Research Unit, CHUQ Research Centre (CHUL), Québec City, Québec, Canada.
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