MDia1

Last updated
Protein diaphanous homolog 1
1z2c asr r 500.jpeg
Crystal structure of mDIA1 GBD-FH3 in complex with RhoC-GMPPNP
Identifiers
SymbolmDia1
Alt. symbolsDRF1
PDB 1z2c
RefSeq NP_031884.1
UniProt o08808

mDia1 (also known as Dia1, Drf1 for Diaphanous-related formin-1, Diaph1, KIAA4062, p140mDia, mKIAA4062, or D18Wsu154e) is a member of the protein family called the formins and is a Rho effector. It is the mouse version of the diaphanous homolog 1 of Drosophila. mDia1 localizes to cells' mitotic spindle and midbody, [1] plays a role in stress fiber and filopodia formation, phagocytosis, activation of serum response factor, formation of adherens junctions, and it can act as a transcription factor. [2] mDia1 accelerates actin nucleation and elongation by interacting with barbed ends (fast-growing ends) of actin filaments. The gene encoding mDia1 is located on Chromosome 18 of Mus musculus and named Diap1.

Contents

mDia1 is highly homologous to Drosophila diaphanous, regulating the cytokinetic ring during cytokinesis. [3] Homologues in other species are known as well, like the human DIAP1, budding yeast Bni1 or fission yeast Cdc12p. [4]

The gene has been knocked-out in mice. [5]

Structure

Fig. 1 Domains of mDia1 shown with relative differences of lengths Mdia1 domains.jpg
Fig. 1 Domains of mDia1 shown with relative differences of lengths

The product of the Diap1 (Diaph1) gene consists of 1255 amino acids resulting in a molecular weight of 139,343 daltons. The mDia1 polypeptide chain can be divided into four protein domains:

Three supplementary domains were discovered:

The active region of the C terminus consists of formin homology 1 and 2 (FH1 and FH2) and the Dia autoregulatory domain (DAD). The FH1 domain is predicted to be rope-like and it contains binding sites for profilin-actin complexes. The adjacent FH2 domain forms together with the FH2 domain of a second mDia1 molecule a head-to-tail doughnut shaped dimer that encircles the barbed end of an actin filament. Thus the FH2 domain has the ability to dimerize. [2]

The N terminus consists of a Rho GTPase-binding domain (GBD), which is joint to the formin homology 3 (FH3).

DAD can mediate autoinhibition through interactions with the Dia inhibitory domain (DID), which is a subdomain of the GDB/FH3 domain (see section Regulation).

Regulation

Autoinhibition is achieved through binding of the C-terminal DAD to the N-terminal DID. This interaction inhibits the ability of FH2 to nucleate actin assembly. [6] Rho-GTP binds to the GDB domain and disrupts the DAD-DID-interaction thus promoting actin assembly. But this requires high concentrations of Rho-GTP, which may be not physiological. Hence, the release of mDia1 from autoinhibition seems to require nonspecific membrane-associated factors that cooperate with Rho-GTP. [7]

Several binding proteins can regulate mDia1 localization and activity: [2]

Furthermore the scaffold protein (IQGAP1) seems to impact on mDia1. IQGAP1 regulates the localization of mDia1 to the leading edge to cells. The only tested short C-terminal fragment of IQGAP1 (aa 1503 to 1657) was not activating the mDia1 actin polymerization activity in vitro. However expression of this fragment in macrophages reduced phagocytosis. [8] Thus it remains open if IQGAP1 influences the activity of mDia1 directly like it does for NWASP. [9] [10]

Mechanism

Nucleation

In contrast to the Arp 2/3 complex, formins nucleate the formation of unbranched actin filaments. FH2 domains lack structural similarity to actin but can bind actin monomers with very weak affinity. [4] The FH2 dimer nucleates filament assembly by interacting directly with and stabilizing actin polymerization intermediates (dimers and trimers).

Elongation

A formin dimer remains constantly bound to the plus end of an actin filament despite ongoing polymerization. One formin of a dimer dissociates from the barbed end to take the next step while the second formin of the dimer remains bound. Thus the formin dimer processively adds actin monomers to the barbed end and are constantly present at the barbed end of an actin filament (processive capping). [4] The FH1 domain recruits actin monomers through profilin binding, but it does not promote nucleation. [2] Studies demonstrated that FH2 domains protect the rapidly elongating barbed ends of filaments from the vast molar excesses of actin capping proteins. [11] [12] [13] The precise mechanisms of actin filament nucleation remains an area of active investigation.

The rate of FH2 movement while elongation on an actin filament matches the rate of actin subunit addition, which can exceed 100 subunits per second.

Profilin as a ubiquitous actin-binding protein is associated with most actin monomers in cells. Interactions between profilin-actin with the FH1 domain can accelerate the elongation at the FH2-capped barbed ends. [2]

Function

The formin homology protein mDia1 is a Rho GTPase effector protein, which appears to be universally present in eukaryotic cells and participates in:

Stress fibers are acto-myosin structures, which are important for establishment of cellular tension and thus traction to move a cell ahead; the later is mediated via cell adhesions. Stress fibers are bundles of about 20 actin filaments linked via non-muscle myosin II. In vitro studies showed that mDia1 assembled stress fibers downstream of Rho. Live-cell imaging analysis revealed that mDia1 indeed assembles stress fibers, which are connected at one of their ends to focal adhesions, where actin polymerization occurs. [14] Stress fiber assembly at focal adhesions by mDia1 was later shown to promote their growth and stabilization, suggesting mDia1 exerts effects on the interactions of cells with their environment. [15]

Formins regulate endocytosis. mDia 1 localizes to endosomes and regulates phagocytic cup formation in macrophages.

mDia1 (and mDia2) seems to stabilize microtubules by decreasing the tubulin subunit exchange at their plus ends. The exact mechanism is not fully understood yet. However, the affinity of formins for actin are much higher than for microtubules. [2]

By catalyzing actin polymerization and stabilizing microtubules, mDia1 plays also an important role for cell migration. [16]

Discovery

mDia1 was discovered as p140mDia1 by Watanabe et al. [3] in 1997 as a downstream effector of Rho. A mouse embryo cDNA library was screened to identify a RhoA-GTP-binding protein using a yeast two-hybrid system. Further it was shown that p140mDia1 binds to the GTP-bound form of RhoA only by precipitation from Swiss 3T3 cell lysates. Watanabe et al. could also show the interaction of p140mDia1 with profilin and the colocalization of RhoA, p140mDia and profilin in membrane ruffles of motile cells.

A subsequent study in 1997 by Bione et al. [17] established a link between human DIA and oogenesis, with a defect in the gene leading to premature ovarian failure.

See also

Related Research Articles

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Profilin

Profilin is an actin-binding protein involved in the dynamic turnover and reconstruction of the actin cytoskeleton. It is found in all eukaryotic organisms in most cells. Profilin is important for spatially and temporally controlled growth of actin microfilaments, which is an essential process in cellular locomotion and cell shape changes. This restructuring of the actin cytoskeleton is essential for processes such as organ development, wound healing, and the hunting down of infectious intruders by cells of the immune system.

FGD1

FYVE, RhoGEF and PH domain-containing protein 1 (FGD1) also known as faciogenital dysplasia 1 protein (FGDY), zinc finger FYVE domain-containing protein 3 (ZFYVE3), or Rho/Rac guanine nucleotide exchange factor FGD1 is a protein that in humans is encoded by the FGD1 gene that lies on the X chromosome. Orthologs of the FGD1 gene are found in dog, cow, mouse, rat, and zebrafish, and also budding yeast and C. elegans. It is a member of the FYVE, RhoGEF and PH domain containing family.

Formins

Formins are a group of proteins that are involved in the polymerization of actin and associate with the fast-growing end of actin filaments. Most formins are Rho-GTPase effector proteins. Formins regulate the actin and microtubule cytoskeleton and are involved in various cellular functions such as cell polarity, cytokinesis, cell migration and SRF transcriptional activity. Formins are multidomain proteins that interact with diverse signalling molecules and cytoskeletal proteins, although some formins have been assigned functions within the nucleus.

Transforming protein RhoA Protein-coding gene in the species Homo sapiens

Transforming protein RhoA, also known as Ras homolog family member A (RhoA), is a small GTPase protein in the Rho family of GTPases that in humans is encoded by the RHOA gene. While the effects of RhoA activity are not all well known, it is primarily associated with cytoskeleton regulation, mostly actin stress fibers formation and actomyosin contractility. It acts upon several effectors. Among them, ROCK1 and DIAPH1 are the best described. RhoA, and the other Rho GTPases, are part of a larger family of related proteins known as the Ras superfamily, a family of proteins involved in the regulation and timing of cell division. RhoA is one of the oldest Rho GTPases, with homologues present in the genomes since 1.5 billion years. As a consequence, RhoA is somehow involved in many cellular processes which emerged throughout evolution. RhoA specifically is regarded as a prominent regulatory factor in other functions such as the regulation of cytoskeletal dynamics, transcription, cell cycle progression and cell transformation.

ROCK1

ROCK1 is a protein serine/threonine kinase also known as rho-associated, coiled-coil-containing protein kinase 1. Other common names are ROKβ and P160ROCK. ROCK1 is a major downstream effecter of the small GTPase RhoA and is a regulator of the actomyosin cytoskeleton which promotes contractile force generation. ROCK1 plays a role in cancer and in particular cell motility, metastasis, and angiogenesis.

IQGAP1

Ras GTPase-activating-like protein IQGAP1 (IQGAP1) also known as p195 is a ubiquitously expressed protein that in humans is encoded by the IQGAP1 gene. IQGAP1 is a scaffold protein involved in regulating various cellular processes ranging from organization of the actin cytoskeleton, transcription, and cellular adhesion to regulating the cell cycle.

RhoC

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PFN2

Profilin-2 is a protein that in humans is encoded by the PFN2 gene.

DIAPH1

Protein diaphanous homolog 1 is a protein that in humans is encoded by the DIAPH1 gene.

FHOD1

FH1/FH2 domain-containing protein 1 is a protein that in humans is encoded by the FHOD1 gene.

DIAPH2

Protein diaphanous homolog 2 is a protein that in humans is encoded by the DIAPH2 gene.

Stress fiber contractile actin bundles found in non-muscle cells

Stress fibers are contractile actin bundles found in non-muscle cells. They are composed of actin (microfilaments) and non-muscle myosin II (NMMII), and also contain various crosslinking proteins, such as α-actinin, to form a highly regulated actomyosin structure within non-muscle cells. Stress fibers have been shown to play an important role in cellular contractility, providing force for a number of functions such as cell adhesion, migration and morphogenesis.

DAAM1

Disheveled-associated activator of morphogenesis 1 is a protein that in humans is encoded by the DAAM1 gene. Evidence of alternative splicing has been observed for this gene but the full-length nature of these variants has not been determined.

Cordon-bleu protein

Protein cordon-bleu is a protein that in humans is encoded by the COBL gene.

Actin assembly-inducing protein

The Actin assembly-inducing protein (ActA) is a protein encoded and used by Listeria monocytogenes to propel itself through a mammalian host cell. ActA is a bacterial surface protein comprising a membrane-spanning region. In a mammalian cell the bacterial ActA interacts with the Arp2/3 complex and actin monomers to induce actin polymerization on the bacterial surface generating an actin comet tail. The gene encoding ActA is named actA or prtB.

Actin remodeling is the biochemical process that allows for the dynamic alterations of cellular organization. The remodeling of actin filaments occurs in a cyclic pattern on cell surfaces and exists as a fundamental aspect to cellular life. During the remodeling process, actin monomers polymerize in response to signaling cascades that stem from environmental cues. The cell's signaling pathways cause actin to affect intracellular organization of the cytoskeleton and often consequently, the cell membrane. Again triggered by environmental conditions, actin filaments break back down into monomers and the cycle is completed. Actin-binding proteins (ABPs) aid in the transformation of actin filaments throughout the actin remodeling process. These proteins account for the diverse structure and changes in shape of Eukaryotic cells. Despite its complexity, actin remodeling may result in complete cytoskeletal reorganization in under a minute.

Rho-associated protein kinase

Rho-associated protein kinase (ROCK) is a kinase belonging to the AGC family of serine-threonine kinases. It is involved mainly in regulating the shape and movement of cells by acting on the cytoskeleton.

FMNL3

Formin-like protein 3 (FMNL3), also known as WW domain-binding protein 3 (WBP-3), is a protein that in humans is encoded by the FMNL3 gene.

References

  1. ↑ Tominaga T, Sahai E, Chardin P, McCormick F, Courtneidge SA, Alberts AS (2000). "Diaphonous-related fromins bridge Rho GTP-ase and Src tyrosine kinase signaling". Mol. Cell. 5 (1): 13–25. doi: 10.1016/S1097-2765(00)80399-8 . PMID   10678165.
  2. 1 2 3 4 5 6 Chesarone MA, DuPage AG, Goode BL (2010). "Unleashing Formins to remodel the actin and microtubule cytoskeletons". Nat. Rev. Mol. Cell Biol. 11 (1): 62–74. doi:10.1038/nrm2816. PMID   19997130. S2CID   8709316.
  3. 1 2 3 Watanabe N, Madaule P, Reid T, Ishizaki T, Watanabe G, Kakizuka A, Saito Y, Nakao K, Jockusch BM, Narumiya S (June 1997). "p140mDia, a mammalian homolog of Drosophila diaphanous, is a target protein for Rho small GTPase and is a ligand for profilin". EMBO J. 16 (11): 3044–56. doi:10.1093/emboj/16.11.3044. PMC   1169923 . PMID   9214622.
  4. 1 2 3 Goode BL, Eck MJ (2007). "Mechanism and function of formins in the control of actin assembly". Annu. Rev. Biochem. 76: 593–627. doi:10.1146/annurev.biochem.75.103004.142647. PMID   17373907.
  5. ↑ Ercan-Sencicek AG, Jambi S, Franjic D, Nishimura S, Li M, El-Fishawy P, Morgan TM, Sanders SJ, Bilguvar K, Suri M, Johnson MH, Gupta AR, Yuksel Z, Mane S, Grigorenko E, Picciotto M, Alberts AS, Gunel M, Sestan N, State MW (2014). "Homozygous loss of DIAPH1 is a novel cause of microcephaly in humans". European Journal of Human Genetics. 23 (2): 165–72. doi:10.1038/ejhg.2014.82. PMC   4297910 . PMID   24781755.
  6. ↑ Nezami AG, Poy F, Eck MJ (February 2006). "Structure of the autoinhibitory switch in formin mDia1". Structure. 14 (2): 257–63. doi: 10.1016/j.str.2005.12.003 . PMID   16472745.
  7. ↑ Seth A, Otomo C, Rosen MK (August 2006). "Autoinhibition regulates cellular localization and actin assembly activity of the diaphanous-related formins FRLalpha and mDia1". J. Cell Biol. 174 (5): 701–13. doi:10.1083/jcb.200605006. PMC   2064313 . PMID   16943183.
  8. ↑ Baarlink C, Grosse R (September 2008). "A GBD uncovered: the FHOD1 N terminus is formin'". Structure. 16 (9): 1287–8. doi: 10.1016/j.str.2008.08.002 . PMID   18786389.
  9. ↑ Le Clainche C, Schlaepfer D, Ferrari A, Klingauf M, Grohmanova K, Veligodskiy A, Didry D, Le D, Egile C, Carlier MF, Kroschewski R (January 2007). "IQGAP1 stimulates actin assembly through the N-WASP-Arp2/3 pathway". J. Biol. Chem. 282 (1): 426–35. doi: 10.1074/jbc.M607711200 . PMID   17085436.
  10. ↑ Brandt DT, Marion S, Griffiths G, Watanabe T, Kaibuchi K, Grosse R (July 2007). "Dia1 and IQGAP1 interact in cell migration and phagocytic cup formation". J. Cell Biol. 178 (2): 193–200. doi:10.1083/jcb.200612071. PMC   2064439 . PMID   17620407.
  11. ↑ Moseley JB, Sagot I, Manning AL, Xu Y, Eck MJ, Pellman D, Goode BL (2004). "A conserved mechanism for Bni1- and mDia1-induced actin assembly and dual regulation of Bni1 by Bud6 and profilin". Mol. Biol. Cell. 15 (2): 896–907. doi:10.1091/mbc.E03-08-0621. PMC   329402 . PMID   14657240.
  12. ↑ Harris ES, Li F, Higgs HN (2004). "The mouse formin, FRLalpha, slows actin filament barbed end elongation, competes with capping protein, accelerates polymerization from monomers, and severs filaments". J. Biol. Chem. 279 (19): 20076–20087. doi: 10.1074/jbc.M312718200 . PMID   14990563.
  13. ↑ Zigmond SH, Evangelista M, Boone C, Yang C, Dar AC, Sicheri F, Forkey J, Pring M (2003). "Formin leaky cap allows elongation in the presence of tight capping proteins". Curr. Biol. 13 (20): 1820–1823. doi: 10.1016/j.cub.2003.09.057 . PMID   14561409. S2CID   18070615.
  14. ↑ Hotulainen P, Lappalainen P (2006). "Stress fibers are generated by two distinct actin assembly mechanisms in motile cells". J. Cell Biol. 173 (3): 383–394. doi:10.1083/jcb.200511093. PMC   2063839 . PMID   16651381.
  15. ↑ Oakes, Patrick W.; Beckham, Yvonne; Stricker, Jonathan; Gardel, Margaret L. (2012-02-06). "Tension is required but not sufficient for focal adhesion maturation without a stress fiber template". The Journal of Cell Biology. 196 (3): 363–374. doi:10.1083/jcb.201107042. ISSN   1540-8140. PMC   3275371 . PMID   22291038.
  16. ↑ Yamana N, Arakawa Y, Nishino T, Kurokawa K, Tanji M, Itoh RE, Monypenny J, Ishizaki T, Bito H, Nozaki K, Hashimoto N, Matsuda M, Narumiya S (2006). "The Rho-mDia1 Pathway Regulates Cell Polarity and Focal Adhesion Turnover in Migrating Cells through Mobilizing Apc and c-Src". Mol. Cell. Biol. 26 (1): 6844–6858. doi:10.1128/MCB.00283-06. PMC   1592856 . PMID   16943426.
  17. ↑ Bione S, Sala C, Manzini C, Arrigo G, Zuffardi O, Banfi S, Borsani G, Jonveaux P, Philippe C, Zuccotti M, Ballabio A, Toniolo D (March 1998). "A human homologue of the Drosophila melanogaster diaphanous gene is disrupted in a patient with premature ovarian failure: evidence for conserved function in oogenesis and implications for human sterility". Am. J. Hum. Genet. 62 (3): 533–41. doi:10.1086/301761. PMC   1376955 . PMID   9497258.
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