The actin filament-associated protein AFAP-110 is an adaptor protein that modulates changes in actin filament integrity

Baisden, Joseph M.; Qian, Yong; Zot, Henry M; Flynn, Daniel C.

doi:10.1038/sj.onc.1204784

Cited by 59 publications

(73 citation statements)

References 79 publications

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“…Previous data predicted that tyrosine phosphorylation may not be responsible for the change in AFAP-110 conformation in response to Src 527F (Qian et al, 1998). Because AFAP-110 is a predicted substrate for PKC phosphorylation (Flynn et al, 1993;Baisden et al, 2001a), PKC is activated in response to Src 527F (Spangler et al, 1989) and because PKC activation directs changes in actin filament integrity (Kiley et al, 1992), we sought to determine whether phosphorylation by PKC may affect AFAP-110 function. To test the hypothesis, purified recombinant AFAP-110 was incubated with recombinant PKC␣ at a molar ratio of 20:1 substrate to enzyme in the presence of radiolabeled ATP.…”

Section: Afap-110 Is Both a Binding Partner And Substrate Of Pkc␣mentioning

confidence: 99%

“…AFAP-110 binds to actin filaments via a carboxy terminal actin binding domain and colocalizes with stress filaments and the cortical actin matrix along the cell membrane (Qian et al, 1998(Qian et al, , 2000. AFAP-110 also binds to Src via SH3 and SH2 binding motifs (Guappone and Flynn, 1997;Guappone et al, 1998) and contains additional amino terminal protein binding modules including two pleckstrin homology (PH) domains, a leucine zipper motif, a target region for serine/threonine phosphorylation as well as other hypothetical protein-binding sites (Baisden et al, 2001a). AFAP-110 is hyperphosphorylated on ser/thr residues as well as tyrosine residues in Src transformed cells and contains numerous consensus sequences for phosphorylation by PKC (Kanner et al, 1991;Flynn et al, 1993).…”

Section: Introductionmentioning

confidence: 99%

“…The actin filament-associated protein of 110 kDa, AFAP-110, was originally identified as a Src 527F binding partner that colocalized with actin filaments (reviewed in Baisden et al, 2001a). AFAP-110 binds to actin filaments via a carboxy terminal actin binding domain and colocalizes with stress filaments and the cortical actin matrix along the cell membrane (Qian et al, 1998(Qian et al, , 2000.…”

Section: Introductionmentioning

confidence: 99%

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PKC Phosphorylation Increases the Ability of AFAP-110 to Cross-link Actin Filaments

Qian

Baisden

Cherezova

et al. 2002

MBoC

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The actin filament-associated protein and Src-binding partner, AFAP-110, is an adaptor protein that links signaling molecules to actin filaments. AFAP-110 binds actin filaments directly and multimerizes through a leucine zipper motif. Cellular signals downstream of Src 527F can regulate multimerization. Here, we determined recombinant AFAP-110 (rAFAP-110)-bound actin filaments cooperatively, through a lateral association. We demonstrate rAFAP-110 has the capability to cross-link actin filaments, and this ability is dependent on the integrity of the carboxy terminal actin binding domain. Deletion of the leucine zipper motif or PKC phosphorylation affected AFAP-110's conformation, which correlated with changes in multimerization and increased the capability of rAFAP-110 to cross-link actin filaments. AFAP-110 is both a substrate and binding partner of PKC. On PKC activation, stress filament organization is lost, motility structures form, and AFAP-110 colocalizes strongly with motility structures. Expression of a deletion mutant of AFAP-110 that is unable to bind PKC blocked the effect of PMA on actin filaments. We hypothesize that upon PKC activation, AFAP-110 can be cooperatively recruited to newly forming actin filaments, like those that exist in cell motility structures, and that PKC phosphorylation effects a conformational change that may enable AFAP-110 to promote actin filament cross-linking at the cell membrane.

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Section: Afap-110 Is Both a Binding Partner And Substrate Of Pkc␣mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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PKC Phosphorylation Increases the Ability of AFAP-110 to Cross-link Actin Filaments

Qian

Baisden

Cherezova

et al. 2002

MBoC

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“…Cellular AFAP-110 can be a nity absorbed from cell lysates with GST-encoded fusion proteins expressing the leucine zipper motif; however, coexpression of Src 527F abrogated the ability of these fusion proteins to absorb cellular AFAP-110. Gel ®ltration analysis con®rmed that AFAP-110 does exist in a selfassociated, multimeric complex as tetramers, trimers and also monomers and that the leucine zipper was necessary for multimerization (Flynn et al, 2001;Qian et al, 1998). Co-expression of Src 527F reduces the size of selfassociated AFAP-110 complexes to a single population hypothesized to represent dimers (Qian et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

“…Because there appeared to be a change in conformation of AFAP-110 in response to Src 527F signaling that e ected the leucine zipper motif, this same motif was deleted (AFAP-110 Dlzip ) and the deletion construct expressed in cells to determine what the e ect of loss of function of the leucine zipper motif may have upon AFAP-110 in cells. Biochemically, deletion of the leucine zipper motif enabled AFAP-110 Dlzip to exist as a dimer, based upon gel ®ltration analysis (Baisden et al, 2001). In cells, expression of AFAP-110 Dlzip a ected a signi®cant change in cell morphology and actin ®lament integrity, repositioning actin ®laments into rosette-like structures, not unlike those seen in Src-transformed cells, and inducing lamellipodia formation (Qian et al, 1998(Qian et al, , 2000.…”

Section: Introductionmentioning

confidence: 99%

The intrinsic ability of AFAP-110 to alter actin filament integrity is linked with its ability to also activate cellular tyrosine kinases

et al. 2001

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The actin ®lament-associated protein of 110 kDa (AFAP-110) is a Src binding partner that represents a potential modulator of actin ®lament integrity in response to cellular signals. Previous reports have demonstrated that AFAP-110 is capable of directly binding and altering actin ®laments. Deletion of the leucine zipper motif of AFAP-110 (AFAP-110 Dlzip ) has been shown to induce a phenotype which resembles Srctransformed cells, by repositioning actin ®laments into rosettes. This deletion also mimics a conformational change in AFAP-110 that is detected in Src-transformed cells. The results presented here indicate that unlike AFAP-110, AFAP-110 Dlzip is capable of activating cellular tyrosine kinases, including Src family members, and that AFAP-110 Dlzip itself is hyperphosphorylated. The newly tyrosine phosphorylated proteins and activated Src-family members appear to be associated with actinrich lamellipodia. A point mutation that alters the SH3-binding motif of AFAP-110 Dlzip prevents it from activating tyrosine kinases and altering actin ®lament integrity. In addition, a deletion within a pleckstrin homology (PH) domain of AFAP-110 Dlzip will also revert its e ects upon actin ®laments. Lastly, dominant-positive RhoA V14 will block the ability of AFAP-110 Dlzip from inducing actin ®lament rosettes, but does not inhibit Src activation. Thus, conformational changes in AFAP-110 enable it to activate cellular kinases in a mechanism requiring SH3 and/or PH domain interactions. We hypothesize that cellular signals which alter AFAP-110 conformation, enable it to activate cellular kinases such as cSrc, which then direct changes in actin ®lament integrity in a Rho-dependent fashion. Oncogene (2001) 20, 6607 ± 6616.

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Structural and functional diversity of adaptor proteins involved in tyrosine kinase signalling

Csiszár¹

2006

BioEssays

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Adaptors are proteins of multi-modular structure without enzymatic activity. Their capacity to organise large, temporary protein complexes by linking proteins together in a regulated and selective fashion makes them of outstanding importance in the establishment and maintenance of specificity and efficiency in all known signal transduction pathways. This review focuses on the structural and functional characterisation of adaptors involved in tyrosine kinase (TK) signalling. TK-linked adaptors can be distinguished by their domain composition and binding specificities. However, such structural classifications have proven inadequate as indicators of functional roles. A better way to understand the logic of signalling networks might be to look at functional aspects of adaptor proteins such as signalling specificity, negative versus positive contribution to signal propagation, or their position in the signalling hierarchy. All of these functions are dynamic, suggesting that adaptors have important regulatory roles rather than acting only as stable linkers in signal transduction.

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The actin filament-associated protein AFAP-110 is an adaptor protein that modulates changes in actin filament integrity

Cited by 59 publications

References 79 publications

PKC Phosphorylation Increases the Ability of AFAP-110 to Cross-link Actin Filaments

PKC Phosphorylation Increases the Ability of AFAP-110 to Cross-link Actin Filaments

The intrinsic ability of AFAP-110 to alter actin filament integrity is linked with its ability to also activate cellular tyrosine kinases

Structural and functional diversity of adaptor proteins involved in tyrosine kinase signalling

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