Pitx2 regulates gonad morphogenesis

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 105; no. 32; pp. 11242 - 11247
• Main Authors: Rodríguez-León, Joaquín, Esteban, Concepción Rodríguez, Martí, Mercè, Santiago-Josefat, Belén, Dubova, Ilir, Rubiralta, Xavier, Belmonte, Juan Carlos Izpisúa
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 12.08.2008; National Acad Sciences
• Subjects: animal ovaries; Animals; Biological Sciences; Birds; Cell adhesion; Cell Adhesion - physiology; Cell Differentiation - physiology; Cell growth; Cell Proliferation; Cellular biology; Chick Embryo; Chickens; Chickens - physiology; chicks; cortex; Cyclin D1 - metabolism; Embryogenesis; Embryology; Embryonic growth stage; Embryos; epithelium; Epithelium - embryology; Female; females; Gene expression; Gene Expression Regulation, Developmental - physiology; genes; Genetics; Germ cells; Germ Cells - cytology; Germ Cells - physiology; Gonads; Homeobox Protein PITX2; Homeodomain Proteins; Male; males; Mitosis; mitotic spindle apparatus; Morphogenesis; Organ Size; ovarian development; Ovary - cytology; Ovary - embryology; Reproductive system; Spindle Apparatus - metabolism; testes; Testis - cytology; Testis - embryology; Topology; Transcription Factors; Vertebrates
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.0804904105

Organ shape and size, and, ultimately, organ function, relate in part to the cell and tissue spatial arrangement that takes place during embryonic development. Despite great advances in the genetic regulatory networks responsible for tissue and organ development, it is not yet clearly understood how specific gene functions are linked to the specific morphogenetic processes underlying the internal organ asymmetries found in vertebrate animals. During female chick embryogenesis, and in contrast to males where both testes develop symmetrically, asymmetrical gonad morphogenesis results in only one functional ovary. The disposition of paired organs along the left-right body axis has been shown to be regulated by the activity of the homeobox containing gene pitx2. We have found that pitx2 regulates cell adhesion, affinity, and cell recognition events in the developing gonad primordium epithelia. This in turn not only allows for proper somatic development of the gonad cortex but also permits the proliferation and differentiation of primordial germ cells. We illustrate how Pitx2 activity directs asymmetrical gonad morphogenesis by controlling mitotic spindle orientation of the developing gonad cortex and how, by modulating cyclinD1 expression during asymmetric ovarian development, Pitx2 appears to control gonad organ size. All together our observations indicate that the effects elicited by Pitx2 during the development of the female chick ovary are critical for cell topology, growth, fate, and ultimately organ morphogenesis and function.