The cell center , or centrosome (from other Greek. Σῶμα - the body) is a non-membrane organoid in eukaryotic cells , consists of two centrioles and a pericentric material. It is the main center for the organization of microtubules (CTMT) of a eukaryotic cell, plays a crucial role in cell division, participating in the formation of the division spindle . From the centrosome, cilia and flagella are formed . Centrosomes are characteristic of animal cells, they are not present in higher plants , in higher fungi, in some protozoa [1] [2] . A number of inherited human diseases are caused by mutations in the genes encoding centrosomal proteins [3] .
Content
History of discovery and change of names
Centrosomes at the poles of the fission spindle in dividing cells were described almost simultaneously by B. Fleming , O. Gertwig and E. van Beneden in the mid-70s of the XIX century. These structures were given the name “centrosphere”, and the granules that could be seen in the focus of the centrosphere were called “polar corpuscles”. Edward van Beneden and Theodor Boveri independently showed that the centrospheres do not disappear at the end of mitosis , but remain in the interphase cell, often located in the region of the geometric center of the cell. In 1887, Edward van Beneden proposed renaming the centrospheres as “central corpuscles” or “central bodies”. In 1888, Theodore Boveri proposed the name “centrosome” for this structure, and later in 1895 - “centriole”. It should be noted that the numerous names of one structure gave rise to terminological confusion, and the terms “centrosome” and “centriole” were used synonymously before the invention of electron microscopy [4] . Since the mid 50-ies of the XX century, when the fine structure of this organelle was studied thanks to electron microscopy, the name "centriole" began to be associated with centriolar cylinders. In 1984, American cell biologist Daniel Mezia proposed the use of the term “centrosome” to refer to the totality of centrioles and their surrounding structures [5] [6] .
Centrosome Design
In many living organisms ( animals and a number of protozoa ), the centrosome contains a pair of centrioles , cylindrical structures located at right angles to each other. Each centriole is formed by nine triplets of microtubules arranged in a circle, as well as a number of structures formed by centrin, cenexin and tectin.
At the interphase of the cell cycle, centrosomes are associated with the nuclear membrane. In the prophase of mitosis, the nuclear membrane is destroyed, the centrosome is divided, and its fission products (daughter centrosomes) migrate to the poles of the fissile nucleus. Microtubules growing from daughter centrosomes are attached at the other end to the so-called kinetochores on the centromeres of chromosomes , forming a spindle of division . At the end of the division, only one centrosome appears in each of the daughter cells.
Centrosome Functions
A centrosome plays a crucial role in cell division, but the presence of a cell center in the cell is not necessary for mitosis [7] . The cell contains one or two centrosomes. An abnormal increase in the number of centrosomes is characteristic of malignant tumor cells. More than two centrosomes are normal for some polyenergy protozoa and syncytial structures.
In addition, centrosomes in non-dividing cells can determine the polarity of the cells. The centrosome in non-dividing cells is often associated with the Golgi apparatus [1] .
In addition to participating in nuclear fission, the centrosome plays an important role in the formation of flagella and cilia. The centrioles located in it act as centers of organization for microtubules of flagella axonems . In organisms lacking centrioles (for example, marsupials and basidium fungi, angiosperms ), flagella do not develop.
Planaria and, possibly, some other flatworms do not have centrosomes (however, in cells carrying cilia , centrioles are formed). [7]
Notes
- ↑ 1 2 Chentsov S. S. Introduction to cell biology / Yu. S. Chentsov. - M: Academic Book, 2005 .-- S. 402-423. - 495 p.
- ↑ Uzbekov R.E., Alieva I. B. Centrosoma - cell accompanist // Nature. - 2007. - No. 5 .
- ↑ Nigg EA, Raff JW Centrioles, centrosomes, and cilia in health and disease // Cell. - 2009. - T. 139 , No. 4 . - S. 663-678 .
- ↑ Uzbekov R.E., Alieva I. B. Centrosome - the riddle of the "cellular processor" // Cytology. - 2008 .-- T. 2 . - S. 91-112 .
- ↑ Uzbekov R.E., Alieva I. B. Centrosoma - the history of study and new discoveries. From the cytoplasmic granule to the central complex of intracellular regulation / R. E. Uzbekov, I. B. Aliev. - M: Publishing house of Moscow University, 2013. - 319 p. - ISBN 978-5-211-06551-2 .
- ↑ Rieder CL, Faruki S., Khodjakov A. The centrosome in vertebrates: more than a microtubule-organizing center // Trends in cell biology. - 2001. - Vol. 11, No. 10 . - P. 413-419. - PMID 11567874 . Archived on October 27, 2007.
- ↑ 1 2 Juliette Azimzadeh, Mei Lie Wong, Diane Miller Downhour, Alejandro Sánchez Alvarado, Wallace F. Marshall. Centrosome Loss in the Evolution of Planarians . Science (January 5, 2012). doi : 10.1126 / science.1214457 . Archived June 2, 2012.
Literature
- Chentsov Yu. S. Introduction to cell biology / Yu. S. Chentsov. - M: Academic Book, 2005 .-- S. 402-423. - 495 p.
- Uzbekov R.E., Alieva I. B. Centrosoma - the history of study and new discoveries. From the cytoplasmic granule to the central complex of intracellular regulation / R. E. Uzbekov, I. B. Aliev. - M: Publishing house of Moscow University, 2013. - 319 p. - ISBN 978-5-211-06551-2 .