Polyproline binding is an essential function of human profilin in yeast

Ostrander, Darin; Ernst, Eileen; Lavoie, Thomas B.; Gorman, Jessica A.

doi:10.1046/j.1432-1327.1999.00354.x

Cited by 33 publications

(22 citation statements)

References 45 publications

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“…Biochemical studies in Acanthamoeba suggest that actin binding is the primary function of profilin (30). However, the binding of other ligands via the poly(L-proline) binding site in profilin is also necessary as revealed by rescue experiments in yeast (31) and Dictyostelium (32). Much as profilin can sequester actin monomers, the interaction with ligands such as Arp2͞3 complex (33), VASP (14), Mena (13), drebrin, gephyrin (16), SMN (17), and others may serve to sequester these ligands until they are needed to trigger a specific cellular process.…”

Section: Discussionmentioning

confidence: 99%

Profilin I is essential for cell survival and cell division in early mouse development

Witke

Sutherland²,

Sharpe³

et al. 2001

Proc. Natl. Acad. Sci. U.S.A.

218

184

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Profilins are thought to play a central role in the regulation of de novo actin assembly by preventing spontaneous actin polymerization through the binding of actin monomers, and the adding of monomeric actin to the barbed actin-filament ends. Other cellular functions of profilin in membrane trafficking and lipid based signaling are also likely. Binding of profilins to signaling molecules such as Arp2͞3 complex, Mena, VASP, N-WASP, dynamin I, and others, further implicates profilin and actin as regulators of diverse motile activities. In mouse, two profilins are expressed from two distinct genes. Profilin I is expressed at high levels in all tissues and throughout development, whereas profilin II is expressed in neuronal cells. To examine the function of profilin I in vivo, we generated a null profilin I (pfn1 ko ) allele in mice. Homozygous pfn1 ko/ko mice are not viable. Pfn1 ko/ko embryos died as early as the two-cell stage, and no pfn1 ko/ko blastocysts were detectable. Adult pfn1 ko/wt mice show a 50% reduction in profilin I expression with no apparent impairment of cell function. However, pfn1 ko/wt embryos have reduced survival during embryogenesis compared with wild type. Although weakly expressed in early embryos, profilin II cannot compensate for lack of profilin I. Our results indicate that mouse profilin I is an essential protein that has dosage-dependent effects on cell division and survival during embryogenesis.

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Section: Discussionmentioning

confidence: 99%

Profilin I is essential for cell survival and cell division in early mouse development

Witke

Sutherland²,

Sharpe³

et al. 2001

Proc. Natl. Acad. Sci. U.S.A.

218

184

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“…Next we sought to determine whether these moderate structural changes between PFN1 WT and M114T mapped to regions involved in PFN1 function, namely to residues that make contact with actin (24-31) or poly-L-proline (21,22,24,32,33). The ternary complex comprised of PFN1 WT, actin, and the poly-Lproline peptide derived from vasodilator-stimulated phosphoprotein (VASP) (21) (PDB ID code 2PAV) is shown in Fig.…”

Section: Als-linked Mutations Induce a Misfolded Conformation Within mentioning

confidence: 99%

Structural basis for mutation-induced destabilization of profilin 1 in ALS

Boopathy

Silvas

Tischbein

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

110

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Mutations in profilin 1 (PFN1) are associated with amyotrophic lateral sclerosis (ALS); however, the pathological mechanism of PFN1 in this fatal disease is unknown. We demonstrate that ALS-linked mutations severely destabilize the native conformation of PFN1 in vitro and cause accelerated turnover of the PFN1 protein in cells. This mutationinduced destabilization can account for the high propensity of ALSlinked variants to aggregate and also provides rationale for their reported loss-of-function phenotypes in cell-based assays. The source of this destabilization is illuminated by the X-ray crystal structures of several PFN1 proteins, revealing an expanded cavity near the protein core of the destabilized M114T variant. In contrast, the E117G mutation only modestly perturbs the structure and stability of PFN1, an observation that reconciles the occurrence of this mutation in the control population. These findings suggest that a destabilized form of PFN1 underlies PFN1-mediated ALS pathogenesis.amyotrophic lateral sclerosis | profilin 1 | protein stability | X-ray crystallography | protein misfolding M utations in the profilin 1 gene (PFN1) were recently associated with both familial and sporadic forms of amyotrophic lateral sclerosis (ALS) (1, 2), an incurable and fatal neurodegenerative disease that primarily targets motor neurons (3). The etiology of sporadic ALS is poorly understood, whereas familial ALS is caused by inheritable genetic defects in defined genes such as PFN1 (3). PFN1 is a 15-kDa protein that is best known for its role in actin dynamics in the context of endocytosis, membrane trafficking, cell motility, and neuronal growth and differentiation (4). In addition to binding monomeric or G-actin, PFN1 also binds to a host of different proteins through their poly-L-proline motifs and to lipids such as phosphatidylinositol 4,5-bisphosphate (4, 5). However, little is known about the mechanism(s) associated with PFN1-mediated ALS pathogenesis. The observation that most ALS-linked PFN1 variants are highly prone to aggregation in mammalian cultured cells suggests that diseasecausing mutations induce an altered, or misfolded, conformation within PFN1 (2). Protein misfolding is a hallmark feature of most neurodegenerative diseases, including ALS (3), and can contribute to disease through both gain-of-toxic-function and loss-of-normalfunction mechanisms (6). Although mutations in PFN1 cause ALS through a dominant inheritance mode (2), there is some evidence supporting a loss-of-function mechanism for mutant PFN1. For example, ALS-linked mutations were shown to abrogate the binding of PFN1 to actin (2) and to impair the incorporation of PFN1 into cytoplasmic stress granules during arsenite-induced stress (7) in cultured cells. Moreover, ectopic expression of these variants in murine motor neurons led to a reduction in both axon outgrowth and growth cone size, consistent with a loss of function through a dominant-negative mechanism (2).Although ALS-linked mutations were shown to induce PFN1 aggregation, the ef...

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“…NCA3 (nuclear control of ATPase) is a nuclear gene involved in the mitochondrial expression of specific subunits of the F 0 -F 1 -ATP synthase (24) but also localizes to the cell wall and plays a role in septation (25,26). NCA3 was identified as a target of the SLN1-SKN7 pathway in microarray experiments 4 and is more abundant and therefore easier to measure than OCH1. As expected for mutations increasing SLN1-SKN7 pathway activity, expression of the OCH1 and NCA3 genes was elevated in the ccw12 mutant (Fig.…”

Section: Ccw12 Involvement In Sln1-skn7mentioning

confidence: 99%

“…Yeast sensors of hyper-osmotic stress are located in the plasma membrane and include the histidine kinase, Sln1p (3,4), as well as the four transmembrane domain protein, Sho1p (5,6). These proteins have distinct relationships to the osmotic response HOG1 MAP 2 kinase pathway that they regulate.…”

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confidence: 99%