The coordinated organization of cells into a precise three-dimensional architecture is important for creating functional organs. Tubulogenesis, or the formation of hollow tubes, is a critical temporary stage in the development of numerous organs.
According to researchers from WOODS HOLE, Massachusetts, The development of hollow, tubular structures of various kinds, including blood vessels, digestive tracts, and complex organs like the heart, kidneys, and mammary glands through branching and differentiation, is one of the most fundamental embryonic processes to occur in virtually every living organism.
Due to the enormous variety of methods that animals employ to build tubular structures, and despite their crucial significance, the general mechanisms of hollow tube creation in the embryo are poorly understood.
The sea star, an ancient marine creature whose process of tubulogenesis is relatively easy to study and which is becoming an important organism for understanding the genetics and mechanics of tube formation.
The Marine Biological Laboratory’s (MBL) Margherita Perillo and colleagues described the beginning and early phases of tube development in the sea star Patiria miniate in the May 9 issue of Nature Communications.
Margherita Perillo from university of Chicago, said, “Most of our organs are tubular because they need to transport fluids or gases or food or blood. And more complex organs like the heart start as a tube and then develop different structures. So, tubulogenesis is a fundamental step to form all our organs.”
Perillo chose the sea star as a research organism. She said, “Because I wanted to understand the basic mechanism of tube formation that is conserved across all vertebrates. So I needed an animal that was at the base along the tree of life, [evolving] before the chordates.”
Perillo and colleagues determined how this organism produces tubes that branch out from its gut by using CRISPR and other methods to examine gene function as well as long time-lapse movies of the developing sea star larvae. Her research identifies a fundamental set of resources from which the chordate tubular organs might have developed.
One open question in biology was exactly how organisms develop from one cell into the complex 3D tubular structures of various organs, Perillo said. In some organisms, such as flies, she said, “there is a big round of cell proliferation before all the cells start to make very complex migration patterns to elongate, change their shapes, and become a tube.”
Cell proliferation and migration occur in other animals, including mammals, in the case of the sea star.
She also said, “I found that, for tube formation, cells can proliferate and migrate simultaneously, as they do in vertebrate development. So this means that this mechanism of making organs was already established at the base or root of the evolution of chordates.”
This gene is responsible for the branching process in tube formation, which is the process by which cells proliferate and migrate to form the complex 3D tubular structures of various organs. In addition to providing insights into the fundamental process that leads to organ formation, sea stars can serve as a model for much biomedical research, such as the discovery of a gene called Six1/2 that regulates the branching process in tube formation.
Researcher said, “I can now use this gene to understand not only how our organs develop but what happens to organs when we have a disease, especially cancer. I hope that, in five to 10 years maximum, we can use this gene to test how organs develop cancer and how cancer becomes metastatic.”
Sea star embryos are ideal for practical experiments because they are largely transparent, allowing for long developing times of direct observation of internal growth processes without causing harm to the organism. Additionally, they are simple to gather and consistently reproduce in significant quantities.