scholarly journals Myosin I Overexpression Impairs Cell Migration

1997 ◽  
Vol 136 (3) ◽  
pp. 633-647 ◽  
Author(s):  
Kristine D. Novak ◽  
Margaret A. Titus
Keyword(s):  
Phosphorylation Site ◽  
Extended Period ◽  
Sh3 Domain ◽  
Developmental Cycle ◽  
Src Homology 3 ◽  
Actin Cortex ◽  
Myosin I ◽  
Src Homology ◽  
Type Rate

Dictyostelium myoB, a member of the myosin I family of motor proteins, is important for controlling the formation and retraction of membrane projections by the cell's actin cortex (Novak, K.D., M.D. Peterson, M.C. Reedy, and M.A. Titus. 1995. J. Cell Biol. 131:1205–1221). Mutants that express a three- to sevenfold excess of myoB (myoB+ cells) were generated to further analyze the role of myosin I in these processes. The myoB+ cells move with an instantaneous velocity that is 35% of the wild-type rate and exhibit a 6–8-h delay in initiation of aggregation when placed under starvation conditions. The myoB+ cells complete the developmental cycle after an extended period of time, but they form fewer fruiting bodies that appear to be small and abnormal. The myoB+ cells are also deficient in their ability both to form distinct F-actin filled projections such as crowns and to become elongate and polarized. This defect can be attributed to the presence of at least threefold more myoB at the cortex of the myoB+ cells. In contrast, threefold overexpression of a truncated myoB that lacks the src homology 3 (SH3) domain (myoB/SH3− cells) or myoB in which the consensus heavy chain phosphorylation site was mutated to an alanine (S332A-myoB) does not disturb normal cellular function. However, there is an increased concentration of myoB in the cortex of the myoB/SH3− and S332A-myoB cells comparable to that found in the myoB+ cells. These results suggest that excess full-length cortical myoB prevents the formation of the actin-filled extensions required for locomotion by increasing the tension of the F-actin cytoskeleton and/ or retracting projections before they can fully extend. They also demonstrate a role for the phosphorylation site and SH3 domain in mediating the in vivo activity of myosin I.

scholarly journals Src-Dependent Phosphorylation of ASAP1 Regulates Podosomes

2007 ◽  
Vol 27 (23) ◽  
pp. 8271-8283 ◽  
Author(s):  
Sanita Bharti ◽  
Hiroki Inoue ◽  
Kapil Bharti ◽  
Dianne S. Hirsch ◽  
Zhongzhen Nie ◽  
...  
Keyword(s):  
Splice Variants ◽  
Phosphorylation Site ◽  
Sh3 Domain ◽  
Tyrosine Kinase Signaling ◽  
Bar Domain ◽  
Src Homology 3 ◽  
3T3 Fibroblasts ◽  
Src Homology ◽  
Nih 3T3 ◽  
Interfering Rna

ABSTRACT Invadopodia are Src-induced cellular structures that are thought to mediate tumor invasion. ASAP1, an Arf GTPase-activating protein (GAP) containing Src homology 3 (SH3) and Bin, amphiphysin, and RVS161/167 (BAR) domains, is a substrate of Src that controls invadopodia. We have examined the structural requirements for ASAP1-dependent formation of invadopodia and related structures in NIH 3T3 fibroblasts called podosomes. We found that both predominant splice variants of ASAP1 (ASAP1a and ASAP1b) associated with invadopodia and podosomes. Podosomes were highly dynamic, with rapid turnover of both ASAP1 and actin. Reduction of ASAP1 levels by small interfering RNA blocked formation of invadopodia and podosomes. Podosomes were formed in NIH 3T3 fibroblasts in which endogenous ASAP1 was replaced with either recombinant ASAP1a or ASAP1b. ASAP1 mutants that lacked the Src binding site or GAP activity functioned as well as wild-type ASAP1 in the formation of podosomes. Recombinant ASAP1 lacking the BAR domain, the SH3 domain, or the Src phosphorylation site did not support podosome formation. Based on these results, we conclude that ASAP1 is a critical target of tyrosine kinase signaling involved in the regulation of podosomes and invadopodia and speculate that ASAP1 may function as a coincidence detector of simultaneous protein association through the ASAP1 SH3 domain and phosphorylation by Src.

scholarly journals The Myosin I SH3 Domain and TEDS Rule Phosphorylation Site are Required for In Vivo Function

1998 ◽  
Vol 9 (1) ◽  
pp. 75-88 ◽  
Author(s):  
Kristine D. Novak ◽  
Margaret A. Titus
Keyword(s):  
Heavy Chain ◽  
Phosphorylation Site ◽  
Sh3 Domain ◽  
Myosin I ◽  
Different Types ◽  
Functional Features ◽  
Actin Expression ◽  
Mutant Forms ◽  
Null Mutants

The class I myosins play important roles in controlling many different types of actin-based cell movements.Dictyostelium cells either lacking or overexpressing amoeboid myosin Is have significant defects in cortical activities such as pseudopod extension, cell migration, and macropinocytosis. The existence of Dictyostelium null mutants with strong phenotypic defects permits complementation analysis as a means of exploring important functional features of the myosin I heavy chain. Mutant Dictyostelium cells lacking two myosin Is exhibit profound defects in growth, endocytosis, and rearrangement of F-actin. Expression of the full-length myoB heavy chain in these cells fully rescues the double mutant defects. However, mutant forms of the myoB heavy chain in which a serine at the consensus phosphorylation site has been altered to an alanine or in which the C-terminal SH3 domain has been removed fail to complement the null phenotype. The wild-type and mutant forms of the myoB heavy chain appeared to be properly localized when they were expressed in the myosin I null mutants. These results suggest that the amoeboid myosin I consensus phosphorylation site and SH3 domains do not play a role in the localization of myosin I, but are absolutely required for in vivo function.

scholarly journals ANKRD54 preferentially selects Bruton’s Tyrosine Kinase (BTK) from a Human Src-Homology 3 (SH3) domain library

PLoS ONE ◽  
2017 ◽  
Vol 12 (4) ◽  
pp. e0174909 ◽  
Author(s):  
Manuela O. Gustafsson ◽  
Dara K. Mohammad ◽  
Erkko Ylösmäki ◽  
Hyunseok Choi ◽  
Subhash Shrestha ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Sh3 Domain ◽  
Bruton’S Tyrosine Kinase ◽  
Bruton's Tyrosine Kinase ◽  
Src Homology 3 ◽  
Src Homology

Interaction of Grb2 SH3 domain with UVRAG in an Alzheimer’s disease–like scenario

2014 ◽  
Vol 92 (3) ◽  
pp. 219-225 ◽  
Author(s):  
Kasturi Roy ◽  
Oishee Chakrabarti ◽  
Debashis Mukhopadhyay
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Growth Factor Receptor ◽  
Adaptor Protein ◽  
Sh3 Domain ◽  
Binding Motifs ◽  
Src Homology 3 ◽  
Src Homology ◽  
Cellular Compartmentalization

Growth factor receptor-bound protein 2 (Grb2) is an adaptor protein which participates in trafficking pathways alongside its role in signaling. Proteins important for actin remodeling and cellular compartmentalization contain SRC Homology 3 (SH3) binding motifs that interact with Grb2. While studying the Grb2–amyloid precursor protein (APP) intracellular domain (AICD) interaction in Alzheimer’s disease cell line models, it was seen that Grb2 colocalized to compartments that mature into autophagosomes. The entrapping of AICD in the Grb2 vesicles and its clearance via autophagosomes was a survival contrivance on the part of the cell. Here, we report that Grb2, when in excess, interacts with ultraviolet radiation resistance-associated gene protein (UVRAG) under excess conditions of AICD–Grb2 or Grb2. The N-terminal SH3 domain of Grb2 specifically interacts with UVRAG, unlike the C-terminal SH3 domain. This interaction helps to understand the role of Grb2 in the autophagic maturation of vesicles.

scholarly journals The PI3K pathway drives the maturation of mast cells via microphthalmia transcription factor

Blood ◽  
2011 ◽  
Vol 118 (13) ◽  
pp. 3459-3469 ◽  
Author(s):  
Peilin Ma ◽  
Raghuveer Singh Mali ◽  
Veerendra Munugalavadla ◽  
Subha Krishnan ◽  
Baskar Ramdas ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Mast Cells ◽  
Pi3k Pathway ◽  
Regulatory Subunit ◽  
Growth And Survival ◽  
Src Homology 3 ◽  
Pi3k Activation ◽  
Src Homology ◽  
Microphthalmia Transcription Factor

Abstract Mast cell maturation is poorly understood. We show that enhanced PI3K activation results in accelerated maturation of mast cells by inducing the expression of microphthalmia transcription factor (Mitf). Conversely, loss of PI3K activation reduces the maturation of mast cells by inhibiting the activation of AKT, leading to reduced Mitf but enhanced Gata-2 expression and accumulation of Gr1+Mac1+ myeloid cells as opposed to mast cells. Consistently, overexpression of Mitf accelerates the maturation of mast cells, whereas Gata-2 overexpression mimics the loss of the PI3K phenotype. Expressing the full-length or the src homology 3– or BCR homology domain–deleted or shorter splice variant of the p85α regulatory subunit of PI3K or activated AKT or Mitf in p85α-deficient cells restores the maturation but not growth. Although deficiency of both SHIP and p85α rescues the maturation of SHIP−/− and p85α−/− mast cells and expression of Mitf; in vivo, mast cells are rescued in some, but not all tissues, due in part to defective KIT signaling, which is dependent on an intact src homology 3 and BCR homology domain of p85α. Thus, p85α-induced maturation, and growth and survival signals, in mast cells can be uncoupled.

scholarly journals Switch-like Arp2/3 activation upon WASP and WIP recruitment to an apparent threshold level by multivalent linker proteins in vivo

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Yidi Sun ◽  
Nicole T Leong ◽  
Tommy Jiang ◽  
Astou Tangara ◽  
Xavier Darzacq ◽  
...  
Keyword(s):  
Quantitative Imaging ◽  
Threshold Level ◽  
Actin Assembly ◽  
Cellular Processes ◽  
Src Homology 3 ◽  
Filament Assembly ◽  
Tightly Coupled ◽  
Src Homology 3 Domain ◽  
Src Homology

Actin-related protein 2/3 (Arp2/3) complex activation by nucleation promoting factors (NPFs) such as WASP, plays an important role in many actin-mediated cellular processes. In yeast, Arp2/3-mediated actin filament assembly drives endocytic membrane invagination and vesicle scission. Here we used genetics and quantitative live-cell imaging to probe the mechanisms that concentrate NPFs at endocytic sites, and to investigate how NPFs regulate actin assembly onset. Our results demonstrate that SH3 (Src homology 3) domain-PRM (proline-rich motif) interactions involving multivalent linker proteins play central roles in concentrating NPFs at endocytic sites. Quantitative imaging suggested that productive actin assembly initiation is tightly coupled to accumulation of threshold levels of WASP and WIP, but not to recruitment kinetics or release of autoinhibition. These studies provide evidence that WASP and WIP play central roles in establishment of a robust multivalent SH3 domain-PRM network in vivo, giving actin assembly onset at endocytic sites a switch-like behavior.

scholarly journals Of Bars and Rings: Hof1-Dependent Cytokinesis in Multiseptated Hyphae of Ashbya gossypii

2008 ◽  
Vol 29 (3) ◽  
pp. 771-783 ◽  
Author(s):  
Andreas Kaufmann ◽  
Peter Philippsen
Keyword(s):  
Ashbya Gossypii ◽  
Actin Ring ◽  
Src Homology 3 ◽  
Filamentous Ascomycete ◽  
Multinucleated Cells ◽  
Ring Assembly ◽  
Src Homology ◽  
Type Ii Myosin ◽  
First Time

ABSTRACT We analyzed the development of multiple septa in elongated multinucleated cells (hyphae) of the filamentous ascomycete Ashbya gossypii in which septation is apparently uncoupled from nuclear cycles. A key player for this compartmentalization is the PCH protein Hof1. Hyphae that are lacking this protein form neither actin rings nor septa but still elongate at wild-type speed. Using in vivo fluorescence microscopy, we present for the first time the coordination of cytokinesis and septation in multiseptated and multinucleated cells. Hof1, the type II myosin Myo1, the landmark protein Bud3, and the IQGAP Cyk1 form collars of cortical bars already adjacent to hyphal tips, thereby marking the sites of septation. While hyphae continue to elongate, these proteins gradually form cortical rings. This bar-to-ring transition depends on Hof1 and Cyk1 but not Myo1 and is required for actin ring assembly. The Fes/CIP4 homology (FCH) domain of Hof1 ensures efficient localization of Hof1, whereas ring integrity is conferred by the Src homology 3 (SH3) domain. Up to several hours after site selection, actin ring contraction leads to membrane invagination and subsequent cytokinesis. Simultaneously, a septum forms between the adjacent hyphal compartments, which do not separate. During evolution, A. gossypii lost the homologs of two enzymes essential for cell separation in Saccharomyces cerevisiae.

scholarly journals Asef2 Functions as a Cdc42 Exchange Factor and Is Stimulated by the Release of an Autoinhibitory Module from a Concealed C-Terminal Activation Element

2006 ◽  
Vol 27 (4) ◽  
pp. 1380-1393 ◽  
Author(s):  
Michael J. Hamann ◽  
Casey M. Lubking ◽  
Doris N. Luchini ◽  
Daniel D. Billadeau
Keyword(s):  
Regulatory Mechanism ◽  
Sh3 Domain ◽  
Terminal Segment ◽  
Binding Region ◽  
Exchange Factor ◽  
Src Homology 3 ◽  
Cell Metastasis ◽  
Src Homology ◽  
And Migration ◽  
Exchange Activity

ABSTRACT Asef (herein called Asef1) was identified as a Rac1-specific exchange factor stimulated by adenomatous polyposis coli (APC), contributing to colorectal cancer cell metastasis. We investigated Asef2, an Asef1 homologue having a similar N-terminal APC binding region (ABR) and Src-homology 3 (SH3) domain. Contrary to previous reports, we found that Asef1 and Asef2 exchange activity is Cdc42 specific. Moreover, the ABR of Asef2 did not function independently but acted in tandem with the SH3 domain to bind APC. The ABRSH3 also bound the C-terminal tail of Asef2, allowing it to function as an autoinhibitory module within the protein. Deletion of the C-terminal tail did not constitutively activate Asef2 as predicted; rather, a conserved C-terminal segment was required for augmented Cdc42 GDP/GTP exchange. Thus, Asef2 activation involves APC releasing the ABRSH3 from the C-terminal tail, resulting in Cdc42 exchange. These results highlight a novel exchange factor regulatory mechanism and establish Asef1 and Asef2 as Cdc42 exchange factors, providing a more appropriate context for understanding the contribution of APC in establishing cell polarity and migration.

Crystal structure of a Src-homology 3 (SH3) domain

Nature ◽  
1992 ◽  
Vol 359 (6398) ◽  
pp. 851-855 ◽  
Author(s):  
Andrea Musacchio ◽  
Martin Noble ◽  
Richard Pauptit ◽  
Rik Wierenga ◽  
Matti Saraste
Keyword(s):  
Crystal Structure ◽  
Sh3 Domain ◽  
Src Homology 3 ◽  
Src Homology
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