Smaug (protein)

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Translational control of nanos mRNA by Smaug protein in Drosophila melanogaster Translation control of nanos mRNA by Smaug protein..jpg
Translational control of nanos mRNA by Smaug protein in Drosophila melanogaster

Smaug is a RNA-binding protein in Drosophila that helps in maternal to zygotic transition (MZT). [3] [4] The protein is named after the fictional character Smaug, the dragon in J.R.R. Tolkien's 1937 novel The Hobbit . [5] The MZT ends with the midblastula transition (MBT), which is defined as the first developmental event in Drosophila that depends on zygotic mRNA. [6] In Drosophila, the initial developmental events are controlled by maternal mRNAs like Hsp83, nanos , string, Pgc, and cyclin B mRNA. [7] [8] [9] [1] [10] Degradation of these mRNAs, which is expected to terminate maternal control and enable zygotic control of embryogenesis, happens at interphase of nuclear division cycle 14. [5] [11] During this transition smaug protein targets the maternal mRNA for destruction using miRs. Thus activating the zygotic genes. Smaug is expected to play a role in expression of three miRNAs – miR-3, miR-6, miR-309 and miR-286 during MZT in Drosophila. [6] Among them smaug dependent expression of miR-309 is needed for destabilization of 410 maternal mRNAs. [12] In smaug mutants almost 85% of maternal mRNA is found to be stable. Smaug also binds to 3′ untranslated region (UTR) elements known as SMG response elements (SREs) on nanos mRNA [13] [14] and represses its expression by recruiting a protein called Cup (an eIF4E-binding protein that blocks the binding of eIF4G to eIF4E). [15] [16] There after it recruits deadenylation complex CCR4-Not on to the nanos mRNA which leads to deadenylation and subsequent decay of the mRNA. [17] It is also found to be involved in degradation and repression of maternal Hsp83 mRNA by recruiting CCR4/POP2/NOT deadenylase to the mRNA. [1] The human Smaug protein homologs are SAMD4A and SAMD4B.

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References

  1. 1 2 3 Semotok, Jennifer L.; Cooperstock, Ramona L.; Pinder, Benjamin D.; Vari, Heli K.; Lipshitz, Howard D.; Smibert, Craig A. (2005-02-22). "Smaug recruits the CCR4/POP2/NOT deadenylase complex to trigger maternal transcript localization in the early Drosophila embryo". Current Biology. 15 (4): 284–294. doi: 10.1016/j.cub.2005.01.048 . ISSN   0960-9822. PMID   15723788.
  2. ↑ Vardy, Leah; Orr-Weaver, Terry L. (2007). "Regulating translation of maternal messages: multiple repression mechanisms". Trends in Cell Biology. 17 (11): 547–554. doi:10.1016/j.tcb.2007.09.002. PMID   18029182.
  3. ↑ Schier, Alexander F. (2007-04-20). "The maternal-zygotic transition: death and birth of RNAs". Science. 316 (5823): 406–407. Bibcode:2007Sci...316..406S. doi:10.1126/science.1140693. ISSN   1095-9203. PMID   17446392. S2CID   36999389.
  4. ↑ Tadros, Wael; Westwood, J. Timothy; Lipshitz, Howard D. (June 2007). "The mother-to-child transition". Developmental Cell. 12 (6): 847–849. doi: 10.1016/j.devcel.2007.05.009 . ISSN   1534-5807. PMID   17543857.
  5. 1 2 Gilbert, Scott F. (2010). Developmental biology (9th ed.). Sunderland, Mass: Sinauer Associates. pp.  205–206. ISBN   9780878933846. OCLC   551199641.
  6. 1 2 Benoit, Beatrice; He, Chun Hua; Zhang, Fan; Votruba, Sarah M.; Tadros, Wael; Westwood, J. Timothy; Smibert, Craig A.; Lipshitz, Howard D.; Theurkauf, William E. (2009-03-15). "An essential role for the RNA-binding protein Smaug during the Drosophila maternal-to-zygotic transition". Development. 136 (6): 923–932. doi:10.1242/dev.031815. ISSN   0950-1991. PMC   2727558 . PMID   19234062.
  7. ↑ Bashirullah, A.; Halsell, S. R.; Cooperstock, R. L.; Kloc, M.; Karaiskakis, A.; Fisher, W. W.; Fu, W.; Hamilton, J. K.; Etkin, L. D. (1999-05-04). "Joint action of two RNA degradation pathways controls the timing of maternal transcript elimination at the midblastula transition in Drosophila melanogaster". The EMBO Journal. 18 (9): 2610–2620. doi:10.1093/emboj/18.9.2610. ISSN   0261-4189. PMC   1171340 . PMID   10228172.
  8. ↑ Bashirullah, A.; Cooperstock, R. L.; Lipshitz, H. D. (2001-06-19). "Spatial and temporal control of RNA stability". Proceedings of the National Academy of Sciences of the United States of America. 98 (13): 7025–7028. Bibcode:2001PNAS...98.7025B. doi: 10.1073/pnas.111145698 . ISSN   0027-8424. PMC   34617 . PMID   11416182.
  9. ↑ Edgar, B. A.; Datar, S. A. (1996-08-01). "Zygotic degradation of two maternal Cdc25 mRNAs terminates Drosophila's early cell cycle program". Genes & Development. 10 (15): 1966–1977. doi: 10.1101/gad.10.15.1966 . ISSN   0890-9369. PMID   8756353.
  10. ↑ Tadros, Wael; Houston, Simon A.; Bashirullah, Arash; Cooperstock, Ramona L.; Semotok, Jennifer L.; Reed, Bruce H.; Lipshitz, Howard D. (July 2003). "Regulation of maternal transcript destabilization during egg activation in Drosophila". Genetics. 164 (3): 989–1001. doi:10.1093/genetics/164.3.989. ISSN   0016-6731. PMC   1462612 . PMID   12871909.
  11. ↑ Tadros, Wael; Goldman, Aaron L.; Babak, Tomas; Menzies, Fiona; Vardy, Leah; Orr-Weaver, Terry; Hughes, Timothy R.; Westwood, J. Timothy; Smibert, Craig A. (2007). "SMAUG Is a Major Regulator of Maternal mRNA Destabilization in Drosophila and Its Translation Is Activated by the PAN GU Kinase". Developmental Cell. 12 (1): 143–155. doi: 10.1016/j.devcel.2006.10.005 . PMID   17199047.
  12. ↑ Bushati, Natascha; Stark, Alexander; Brennecke, Julius; Cohen, Stephen M. (2008-04-08). "Temporal reciprocity of miRNAs and their targets during the maternal-to-zygotic transition in Drosophila". Current Biology. 18 (7): 501–506. doi: 10.1016/j.cub.2008.02.081 . ISSN   0960-9822. PMID   18394895.
  13. ↑ Smibert, C. A.; Lie, Y. S.; Shillinglaw, W.; Henzel, W. J.; Macdonald, P. M. (December 1999). "Smaug, a novel and conserved protein, contributes to repression of nanos mRNA translation in vitro". RNA. 5 (12): 1535–1547. doi:10.1017/S1355838299991392. ISSN   1355-8382. PMC   1369876 . PMID   10606265.
  14. ↑ Dahanukar, A.; Walker, J. A.; Wharton, R. P. (August 1999). "Smaug, a novel RNA-binding protein that operates a translational switch in Drosophila". Molecular Cell. 4 (2): 209–218. doi: 10.1016/S1097-2765(00)80368-8 . ISSN   1097-2765. PMID   10488336.
  15. ↑ Nelson, Meryl R.; Leidal, Andrew M.; Smibert, Craig A. (2004-01-14). "Drosophila Cup is an eIF4E-binding protein that functions in Smaug-mediated translational repression". The EMBO Journal. 23 (1): 150–159. doi:10.1038/sj.emboj.7600026. ISSN   0261-4189. PMC   1271664 . PMID   14685270.
  16. ↑ Nakamura, Akira; Sato, Keiji; Hanyu-Nakamura, Kazuko (January 2004). "Drosophila cup is an eIF4E binding protein that associates with Bruno and regulates oskar mRNA translation in oogenesis". Developmental Cell. 6 (1): 69–78. doi: 10.1016/S1534-5807(03)00400-3 . ISSN   1534-5807. PMID   14723848.
  17. ↑ Zaessinger, Sophie; Busseau, Isabelle; Simonelig, Martine (November 2006). "Oskar allows nanos mRNA translation in Drosophila embryos by preventing its deadenylation by Smaug/CCR4". Development. 133 (22): 4573–4583. doi: 10.1242/dev.02649 . ISSN   0950-1991. PMID   17050620.
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