PRC1 explained

Protein Regulator of cytokinesis 1 (PRC1) is a protein that in humans is encoded by the PRC1 gene and is involved in cytokinesis.^{[1] [2]}

Function

PRC1 protein is expressed at relatively high levels during S and G2/M phases of the cell cycle before dropping dramatically after mitotic exit and entrance into G1 phase. PRC1 is located in the nucleus during interphase, becomes associated with the mitotic spindle in a highly dynamic manner during anaphase, and localizes to the cell midbody during cytokinesis. PRC1 was first identified in 1998 using an ''in vitro'' phosphorylation screening method and shown to be a substrate of several cyclin-dependent kinases (CDKs). Correspondingly, ablation of PRC1 has been shown to disrupt spindle midzone assembly in mammalian systems.^[3]

At least three alternatively spliced transcript variants encoding distinct isoforms of PRC1 have been observed. Additionally, PRC1 has sequence homology with Ase1 in yeasts, SPD-1 (spindle defective 1) in C. elegans, Feo in D. melanogaster, and MAP65 in plants, all of which fall in a conserved family of nonmotor microtubule-associated proteins (MAPs).^{[4] [5] [6]}

Structure

The crystal structure of PRC1 has only recently been characterized in vitro. In 2013, PRC1 was illustrated as a lengthy molecule consisting of a C-terminal spectrin microtubule-binding domain, an extended rod domain, and an N-terminal dimerization domain.^{[5] [7]} Consisting of an intricate arrangement of α-helices, the rod domain, together with the dimerization-conducting N terminus cooperate to facilitate binding of other proteins, such as Kinesin-4, to PRC1. PRC1’s rod domain adopts multiple conformations, all affected by its C-terminal spectrin domain. A model has been suggested in which PRC1 is likely to be a flexible molecule both in solution and on single microtubules but becomes more rigid when the microtubule-binding domains are restricted with antiparallel microtubule filament crosslinking, seen at the spindle midzone. The overall structure of the PRC1 homodimer is reminiscent of actin-bundling proteins, and this process of microtubule filament crosslinking is similar to that of actin.^[5]

Role in cytokinesis

PRC1’s role in midzone microtubule formation, essential to the cytokinetic machinery of mammals, is made possible through its collaboration with Kinesin-4 in setting up a controlled zone of overlapping, antiparallel microtubules at the spindle midzone. PRC1 is normally inhibited until anaphase onset by CDK1 mediated phosphorylation, preventing its dimerization. Upon anaphase onset and removal of inhibitory CDK1 phosphorylation, PRC1 dimers form. These homodimers specifically recognize antiparallel microtubule overlaps, found at the spindle midzone, and bind, allowing microtubule sliding, cross-linking of microtubule filaments, and assembly of central-spindle-mediating proteins, including but not limited to Kinesin-4.

PRC1 dimers, required for the high-affinity interaction with Kinesin-4, recruit Kinesin-4 to regions of antiparallel microtubule overlap, where Kinesin-4, a plus-end directed motor protein that inhibits microtubule dynamics, helps to form length-dependent end tags that help stabilize and regulate spindle microtubule assembly within cytokinesis.^[5] This PRC1-Kinesin-4 complex differentially identifies and regulates the spindle midzone microtubules during cell division. This regulation is crucial in order for cytokinesis to progress properly.

Interactions

• PRC1 is a non-motor microtubule-associated protein (MAP) whose C-terminal spectrin domain (aa 341-640) binds microtubules with micromolar affinity (0.6 +/- 0.3uM) ^[8]
• PRC1 has been shown to interact with TRIM37.^[9]
• PRC1 interacts with Kinesin-4 that plays an important role in crossing spindle microtubules and setting midzone length in mammalian cytokinesis.^[5]
• PRC1 is negatively modulated by CDKs, particularly CDK1.^[10]
• PLK1 negatively regulates PRC1 through phosphorylation at Thr-602, near the C-terminus of PRC1, only after dephosphorylation of PRC1 at an inhibitory CDK1 site.^{[11] [12]}
• PRC1 binds directly to CYK-4 subunit of the centralspindlin complex to stabilise the central spindle.^[13]

Further reading

• Mollinari C, Kleman JP, Jiang W, Schoehn G, Hunter T, Margolis RL . PRC1 is a microtubule binding and bundling protein essential to maintain the mitotic spindle midzone. . J. Cell Biol. . 157 . 7 . 1175–86 . 2002 . 12082078 . 2173564 . 10.1083/jcb.200111052 .
• Ban R, Irino Y, Fukami K, Tanaka H . Human mitotic spindle-associated protein PRC1 inhibits MgcRacGAP activity toward Cdc42 during the metaphase. . J. Biol. Chem. . 279 . 16 . 16394–402 . 2004 . 14744859 . 10.1074/jbc.M313257200 . free .
• Kurasawa Y, Earnshaw WC, Mochizuki Y, Dohmae N, Todokoro K . Essential roles of KIF4 and its binding partner PRC1 in organized central spindle midzone formation. . EMBO J. . 23 . 16 . 3237–48 . 2005 . 15297875 . 514520 . 10.1038/sj.emboj.7600347 .
• Li C, Lin M, Liu J . Identification of PRC1 as the p53 target gene uncovers a novel function of p53 in the regulation of cytokinesis. . Oncogene . 23 . 58 . 9336–47 . 2005 . 15531928 . 10.1038/sj.onc.1208114 . free .
• Mollinari C, Kleman JP, Saoudi Y, Jablonski SA, Perard J, Yen TJ, Margolis RL . Ablation of PRC1 by small interfering RNA demonstrates that cytokinetic abscission requires a central spindle bundle in mammalian cells, whereas completion of furrowing does not. . Mol. Biol. Cell . 16 . 3 . 1043–55 . 2005 . 15616196 . 551472 . 10.1091/mbc.E04-04-0346 .
• Zhu C, Jiang W . Cell cycle-dependent translocation of PRC1 on the spindle by Kif4 is essential for midzone formation and cytokinesis. . Proc. Natl. Acad. Sci. U.S.A. . 102 . 2 . 343–8 . 2005 . 15625105 . 544298 . 10.1073/pnas.0408438102 . 2005PNAS..102..343Z . free .
• Rual JF, Venkatesan K, Hao T, Hirozane-Kishikawa T, Dricot A, Li N, Berriz GF, Gibbons FD, Dreze M, Ayivi-Guedehoussou N, Klitgord N, Simon C, Boxem M, Milstein S, Rosenberg J, Goldberg DS, Zhang LV, Wong SL, Franklin G, Li S, Albala JS, Lim J, Fraughton C, Llamosas E, Cevik S, Bex C, Lamesch P, Sikorski RS, Vandenhaute J, Zoghbi HY, Smolyar A, Bosak S, Sequerra R, Doucette-Stamm L, Cusick ME, Hill DE, Roth FP, Vidal M . Towards a proteome-scale map of the human protein-protein interaction network. . Nature . 437 . 7062 . 1173–8 . 2005 . 16189514 . 10.1038/nature04209 . 2005Natur.437.1173R . 4427026 .
• Nousiainen M, Silljé HH, Sauer G, Nigg EA, Körner R . Phosphoproteome analysis of the human mitotic spindle. . Proc. Natl. Acad. Sci. U.S.A. . 103 . 14 . 5391–6 . 2006 . 16565220 . 1459365 . 10.1073/pnas.0507066103 . 2006PNAS..103.5391N . free .
• Zhu C, Lau E, Schwarzenbacher R, Bossy-Wetzel E, Jiang W . Spatiotemporal control of spindle midzone formation by PRC1 in human cells. . Proc. Natl. Acad. Sci. U.S.A. . 103 . 16 . 6196–201 . 2006 . 16603632 . 1458854 . 10.1073/pnas.0506926103 . 2006PNAS..103.6196Z . free .
• Beausoleil SA, Villén J, Gerber SA, Rush J, Gygi SP . A probability-based approach for high-throughput protein phosphorylation analysis and site localization. . Nat. Biotechnol. . 24 . 10 . 1285–92 . 2006 . 16964243 . 10.1038/nbt1240 . 14294292 .
• Shimo A, Nishidate T, Ohta T, Fukuda M, Nakamura Y, Katagiri T . Elevated expression of protein regulator of cytokinesis 1, involved in the growth of breast cancer cells. . Cancer Sci. . 98 . 2 . 174–81 . 2007 . 17233835 . 10.1111/j.1349-7006.2006.00381.x . 1635584 . 11159940 .
• Subramanian R, Wilson-Kubalek EM, Arthur CP, Bick MJ, Campbell EA, Darst SA, Milligan RA, Kapoor TM . Insights into antiparallel microtubule crosslinking by PRC1, a conserved nonmotor microtubule binding protein. . Cell . 142 . 3 . 433–43 . 2010 . 20691902 . 2966277 . 10.1016/j.cell.2010.07.012 .

Notes and References

1. Jiang W, Jimenez G, Wells NJ, Hope TJ, Wahl GM, Hunter T, Fukunaga R . PRC1: a human mitotic spindle-associated CDK substrate protein required for cytokinesis. . Mol. Cell . 2 . 6 . 877–85 . 1998 . 9885575 . 10.1016/S1097-2765(00)80302-0 . free .
2. Web site: Entrez Gene: PRC1 protein regulator of cytokinesis 1.
3. Eggert US, Mitchison TJ, Field CM . Animal Cytokinesis: From Parts List to Mechanisms. . Annu. Rev. Biochem. . 75 . 543–66 . 2006 . 16756502 . 10.1146/annurev.biochem.74.082803.133425 .
4. Bieling P, Telley IA, Surrey T . A Minimal Midzone Protein Module Controls Formation and Length of Antiparallel Microtubule Overlaps. . Cell . 142 . 3 . 420–32 . 2010 . 20691901 . 10.1016/j.cell.2010.06.033 . free .
5. Subramanian R, Ti SC, Tan L, Darst SA, Kapoor TM . Marking and Measuring Single Microtubules by PRC1 and Kinesin-4. . Cell . 154 . 2. 377–90 . 2013 . 23870126 . 3761943 . 10.1016/j.cell.2013.06.021 .
6. Vernì F, Somma MP, Gunsalus KC, Bonaccorsi S, Belloni G, Goldberg ML, Gatti M . Feo, the Drosophila Homolog of PRC1, Is Required for Central-Spindle Formation and Cytokinesis. . Curr. Biol. . 14 . 17 . 1569–75 . 2004 . 15341744 . 10.1016/j.cub.2004.08.054 . free . 2004CBio...14.1569V .
7. Hu CK, Coughlin M, Mitchison TJ . Midbody assembly and its regulation during cytokinesis. . Mol. Biol. Cell . 23 . 6. 1024–34 . 2012 . 22278743 . 3302730 . 10.1091/mbc.E11-08-0721 .
8. Subramanian R, Wilson-Kubalek EM, Arthur CP, Bick MJ, Campbell EA, Darst SA, Milligan RA, Kapoor TM . Insights into antiparallel microtubule crosslinking by PRC1, a conserved nonmotor microtubule binding protein . en . Cell . 142 . 3 . 433–43 . Aug 2010 . 20691902 . 2966277 . 10.1016/j.cell.2010.07.012 .
9. Rual JF, Venkatesan K, Hao T, Hirozane-Kishikawa T, Dricot A, Li N, Berriz GF, Gibbons FD, Dreze M, Ayivi-Guedehoussou N, Klitgord N, Simon C, Boxem M, Milstein S, Rosenberg J, Goldberg DS, Zhang LV, Wong SL, Franklin G, Li S, Albala JS, Lim J, Fraughton C, Llamosas E, Cevik S, Bex C, Lamesch P, Sikorski RS, Vandenhaute J, Zoghbi HY, Smolyar A, Bosak S, Sequerra R, Doucette-Stamm L, Cusick ME, Hill DE, Roth FP, Vidal M . Towards a proteome-scale map of the human protein-protein interaction network. . Nature . 437 . 7062 . 1173–8 . 2005 . 16189514 . 10.1038/nature04209 . 2005Natur.437.1173R . 4427026 .
10. Fededa JP, Gerlich DW . Molecular Control of animal cell cytokinesis . Nat. Cell Biol. . 14 . 5 . 440–7 . 2012 . 22552143 . 10.1038/ncb2482 . 3355851 . 11336/20338 . free .
11. Bechstedt S, Brouhard GJ . Motors and MAPs Collaborate to Size Up Microtubules. . Dev. Cell . 26 . 2 . 118–20 . 2013 . 23906062 . 10.1016/j.devcel.2013.07.010 . free .
12. Hu CK, Ozlü N, Coughlin M, Steen JJ, Mitchison TJ . Plk1 negatively regulates PRC1 to prevent premature midzone formation before cytokinesis. . Mol. Biol. Cell . 23 . 4 . 2702–11 . 2012 . 22621898 . 3395659 . 10.1091/mbc.E12-01-0058 .
13. Lee KY, Esmaeili B, Zealley B, Mishima M . Direct interaction between centralspindlin and PRC1 reinforces mechanical resilience of the central spindle . Nature Communications . 6 . 7290 . 2015 . 26088160 . 10.1038/ncomms8290 . 4557309. 2015NatCo...6.7290L .