scholarly journals 436. Investigation of the role of SRC in capacitation associated tyrosine phosphorylation of human spermatozoa

2008 ◽  
Vol 20 (9) ◽  
pp. 116
Author(s):  
L. A. Mitchell ◽  
B. Nixon ◽  
M. A. Baker ◽  
R. J. Aitken
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Phosphorylation ◽  
Signal Transduction Pathway ◽  
Human Sperm ◽  
Complex Signal ◽  
Phosphorylation Cascade ◽  
A Site ◽  
Signalling Cascade ◽  
Mammalian Spermatozoa

Capacitation is a pre-requisite for mammalian spermatozoa allowing them to gain the ability to fertilise an oocyte. A fundamental part of this mechanism is a dramatic increase in tyrosine phosphorylation. Implicated in this process in the mouse is a unique cAMP/PKA-mediated pathway involving a PKA-activated tyrosine kinase suggested to be pp60c-src (SRC). The Src kinases examined were predominantly expressed in the human sperm tail, a site compatible with a role in mediating the capacitation-associated tyrosine phosphorylation cascade. Co-immunoprecipitation revealed that PKA-c could be isolated from sperm and this interaction was restricted to capacitated cells, suggesting PKA-mediated activation of SRC forms an integral part of the signalling cascade assembled during capacitation. Upon activation, SRC undergoes autophosphorylation of Y416 and thus phosphorylation of this residue indicates the presence of active SRC kinase. The phosphorylation status of SRC was compared using both 2D-immunoblotting and immunocytochemical studies, both revealing a significant increase in SRC activation during capacitation. Furthermore, suppression of PKA and SRC through application of SU6656, or H89, a PKA inhibitor, led to a dramatic decrease in tyrosine phosphorylation and SRC activity. In conclusion, this study has provided evidence for the involvement of non-receptor tyrosine kinase, SRC, in regulating tyrosine phosphorylation associated with capacitation. Inhibition of SRC did not completely suppress tyrosine phosphorylation suggesting this complex signal transduction pathway exhibits a degree of functional redundancy.

Oncoprotein-mediated signalling cascade stimulates c-Jun activity by phosphorylation of serines 63 and 73

1992 ◽  
Vol 12 (8) ◽  
pp. 3507-3513
Author(s):  
T Smeal ◽  
B Binetruy ◽  
D Mercola ◽  
A Grover-Bardwick ◽  
G Heidecker ◽  
...  
Keyword(s):  
Dna Binding ◽  
Signal Transduction Pathway ◽  
Resting Cells ◽  
Dna Binding Domain ◽  
Transduction Pathway ◽  
Ras Protein ◽  
Downstream Target ◽  
Phosphorylation Cascade ◽  
Serum Dependent ◽  
Signalling Cascade

In resting cells, c-Jun is phosphorylated on five sites. Three of these sites reside next to its DNA binding domain and negatively regulate DNA binding. In response to expression of oncogenic Ha-Ras, phosphorylation of these sites decreases, while phosphorylation of two other sites within c-Jun's activation domain is greatly enhanced. Phosphorylation of these residues, serines 63 and 73, stimulates the transactivation function of c-Jun and is required for oncogenic cooperation with Ha-Ras. We now show that the same changes in c-Jun phosphorylation are elicited by a variety of transforming oncoproteins with distinct biochemical activities. These oncoproteins, v-Sis, v-Src, Ha-Ras, and Raf-1, participate in a signal transduction pathway that leads to increased phosphorylation of serines 63 and 73 on c-Jun. While oncogenic Ha-Ras is a constitutive stimulator of c-Jun activity and phosphorylation, the normal c-Ha-Ras protein is a serum-dependent modulator of c-Jun's activity. c-Jun is therefore a downstream target for a phosphorylation cascade involved in cell proliferation and transformation.

Autonomous expression of a noncatalytic domain of the focal adhesion-associated protein tyrosine kinase pp125FAK

1993 ◽  
Vol 13 (2) ◽  
pp. 785-791
Author(s):  
M D Schaller ◽  
C A Borgman ◽  
J T Parsons
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Phosphorylation ◽  
Focal Adhesion ◽  
Protein Tyrosine Kinase ◽  
Signal Transduction Pathway ◽  
Focal Adhesions ◽  
Cellular Adhesion ◽  
Protein Tyrosine ◽  
Intracellular Signals ◽  
Embryo Cells

Integrins play a central role in cellular adhesion and anchorage of the cytoskeleton and participate in the generation of intracellular signals, including tyrosine phosphorylation. We have recently isolated a cDNA encoding a unique, focal adhesion-associated protein tyrosine kinase (FAK) that is a component of an integrin-mediated signal transduction pathway. Here we report the isolation of cDNAs encoding the C-terminal, noncatalytic domain of the FAK kinase, termed FRNK (FAK-related nonkinase). Both the FAK- and FRNK-encoded polypeptides, pp125FAK and p41/p43FRNK, are expressed in normal chicken embryo cells. pp125FAK and p41/p43FRNK were localized to focal adhesions, suggesting that pp125FAK is directed to the focal adhesions by sequences within its C-terminal domain. We also show that the fibronectin-dependent increase in tyrosine phosphorylation of pp125FAK is accompanied by a concomitant posttranslational modification of p41FRNK.

scholarly journals Endosomal Localization and Receptor Dynamics Determine Tyrosine Phosphorylation of Hepatocyte Growth Factor-Regulated Tyrosine Kinase Substrate

2000 ◽  
Vol 20 (20) ◽  
pp. 7685-7692 ◽  
Author(s):  
Sylvie Urbé ◽  
Ian G. Mills ◽  
Harald Stenmark ◽  
Naomi Kitamura ◽  
Michael J. Clague
Keyword(s):  
Growth Factor ◽  
Hepatocyte Growth Factor ◽  
Tyrosine Kinase ◽  
Tyrosine Phosphorylation ◽  
Membrane Trafficking ◽  
Signal Transduction Pathway ◽  
Dominant Negative ◽  
Kinase Substrate ◽  
Hepatocyte Growth ◽  
Tyrosine Kinase Substrate

ABSTRACT Hepatocyte growth factor-regulated tyrosine kinase substrate (Hrs) is a prominent substrate for activated tyrosine kinase receptors that has been proposed to play a role in endosomal membrane trafficking. The protein contains a FYVE domain, which specifically binds to the lipid phosphatidylinositol (PI) 3-phosphate (PI 3-P). We show that this interaction is required both for correct localization of the protein to endosomes that only partially coincides with early endosomal autoantigen 1 and for efficient tyrosine phosphorylation of the protein in response to epidermal growth factor stimulation. Treatment with wortmannin reveals that Hrs phosphorylation also requires PI 3-kinase activity, which is necessary to generate the PI 3-P required for localization. We have used both hypertonic media and expression of a dominant-negative form of dynamin (K44A) to inhibit endocytosis; under which conditions, receptor stimulation fails to elicit phosphorylation of Hrs. Our results provide a clear example of the coupling of a signal transduction pathway to endocytosis, from which we propose that activated receptor (or associated factor) must be delivered to the appropriate endocytic compartment in order for Hrs phosphorylation to occur.

TCF: Lady Justice Casting the Final Verdict on the Outcome of Wnt Signalling

2002 ◽  
Vol 383 (2) ◽  
pp. 255-261 ◽  
Author(s):  
H. Brantjes ◽  
N. Barker ◽  
J. van Es ◽  
H. Clevers
Keyword(s):  
Cell Fate ◽  
Target Genes ◽  
Signal Transduction Pathway ◽  
Wnt Signalling ◽  
Early Event ◽  
Embryonic Patterning ◽  
Repressor Proteins ◽  
Downstream Effectors ◽  
Signalling Cascade

Abstract The Wnt signalling cascade plays an important role during embryonic patterning and cell fate determination and is highly conserved throughout evolution. Factors of the TCF/LEF HMG domain family (Tcfs) are the downstream effectors of this signal transduction pathway. Upon Wnt signalling, a cascade is initiated that results in the translocation of βcatenin to the nucleus, where it interacts with Tcf to generate a transcriptionally active complex. This bipartite transcription factor is targeted to the upstream regulatory regions of Tcf target genes. In the absence of Wnt signals, βcatenin is degraded in the cytoplasm via the ubiquitinproteasome pathway. Several proteins are instrumental in achieving this tight regulation of βcatenin levels in the cell, including adenomatous polyposis coli (APC), GSK3 β, and Axin/Conductin. Deregulation of the Wnt signalling pathway is implicated in several forms of cancer, such as colon carcinoma and melanoma. This deregulation is achieved via mutation of APC, βcatenin or Axin, resulting in elevated βcatenin levels and the presence of constitutively active Tcfβcatenin complexes in the nucleus. The accompanying inappropriate activation of target genes is considered to be a critical, early event in this carcinogenesis. In addition to regulating βcatenin levels, normal healthy cells have evolved a second level of regulation, by manipulating the activity of the Tcf proteins themselves. In the absence of Wnt signalling, Tcf complexes with several transcriptional repressor proteins ensuring active repression of Tcf target genes. In this review the dual role of Tcf proteins in the Wnt signalling cascade will be discussed.

Sperm Proteasome Activity Is Necessary for Tyrosine Phosphorylation During Human Sperm Capacitation: Possible Role of P42 Protein.

2012 ◽  
Vol 87 (Suppl_1) ◽  
pp. 425-425
Author(s):  
Lidia M. Zuñiga ◽  
Kely Ordenes ◽  
Emilce S. Diaz ◽  
Patricio Morales
Keyword(s):  
Tyrosine Phosphorylation ◽  
Human Sperm ◽  
Proteasome Activity ◽  
Sperm Capacitation

Role of tyrosine kinase pathways in ETB receptor activation of NHE3

1996 ◽  
Vol 271 (3) ◽  
pp. C763-C771 ◽  
Author(s):  
T. S. Chu ◽  
H. Tsuganezawa ◽  
Y. Peng ◽  
A. Cano ◽  
M. Yanagisawa ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Phosphorylation ◽  
Focal Adhesion ◽  
Focal Adhesions ◽  
Integral Membrane Protein ◽  
Receptor Activation ◽  
Kinase C ◽  
Focal Adhesion Proteins ◽  
Etb Receptor

Endothelin-1 (ET-1) binding to ETB receptors increases the activity of the apical membrane Na+/H+ antiporter (NHE3) of renal proximal tubule and cultured OKP cells. In OKPETB6 cells, a clonal cell line of OKP cells that overexpresses ETB receptors, ET-1-induced increases in Na+/H+ antiporter activity are mediated 50% by Ca2(+)-dependent pathways and 50% by tyrosine kinase pathways. ET-1 induces tyrosine phosphorylation of proteins of 68, 110, 125, 130, and 210 kDa. ET-1-induced tyrosine phosphorylation is mediated by the ETB receptor and is not dependent on increases in cell Ca2+ or protein kinase C. The 68-, 110-, 125-, and 130-kDa phosphoproteins are cytosolic, whereas the 210-kDa phosphoprotein is an integral membrane protein. Immunoprecipitation studies showed that the 68-kDa protein is paxillin and the 125-kDa protein is p125FAK (focal adhesion kinase). Cytochalasin D, which disrupts focal adhesions, prevented ET-1-induced tyrosine phosphorylation of paxillin, p110, p125FAK, and p130 but did not prevent tyrosine phosphorylation of p210 and did not prevent ET-1-induced increases in Na+/H+ antiporter activity. Thus 50% of ETB receptor-induced Na+/H+ antiporter activation is mediated by tyrosine kinase pathways, possibly involving p210. ETB receptor activation also induces tyrosine phosphorylation of focal adhesion proteins, but this is not required for antiporter activation.

scholarly journals A Collagen-Like Peptide Stimulates Tyrosine Phosphorylation of syk and Phospholipase Cγ2 in Platelets Independent of the Integrin α2β1

Blood ◽  
1997 ◽  
Vol 89 (4) ◽  
pp. 1235-1242 ◽  
Author(s):  
Judith Asselin ◽  
Jonathan M. Gibbins ◽  
Marcus Achison ◽  
Young Han Lee ◽  
Laurence F. Morton ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Phosphorylation ◽  
Platelet Activation ◽  
Protein Tyrosine Phosphorylation ◽  
Direct Role ◽  
Amino Acid Code ◽  
Helical Peptide ◽  
Platelet Receptor ◽  
Dependent Pathway

AbstractActivation of platelets by collagen is mediated through a tyrosine kinase-dependent pathway that is associated with phosphorylation of the Fc receptor γ chain, the tyrosine kinase syk, and phospholipase Cγ2 (PLCγ2). We recently described a collagen-related triple-helical peptide (CRP) with the sequence GCP*(GPP*)GCP*G (single letter amino acid code: P* = hydroxyproline; Morton et al, Biochem J 306:337, 1995). The cross-linked peptide is a potent stimulus of platelet activation but, unlike collagen, does not support α2β1-mediated, Mg2+-dependent adhesion, suggesting that its action is independent of the integrin α2β1 . This finding suggests the existence of a platelet receptor other than α2β1 that underlies activation. In the present study, we show that CRP stimulates tyrosine phosphorylation of the same pattern of proteins in platelets as collagen, including syk and PLCγ2. Protein tyrosine phosphorylation induced by CRP is not altered in the absence of Mg2+ or the presence of monoclonal antibodies (MoAbs) to the integrin α2β1 (MoAb 6F1 and MoAb 13), conditions that prevent the interaction of collagen with the integrin. In contrast, phosphorylation of syk and PLCγ2 by collagen is partially reduced by MoAb 6F1 and MoAb 13 or by removal of Mg2+. This may reflect a direct role of α2β1 in collagen-induced signaling events or an indirect role in which the integrin facilitates the binding of collagen to its signaling receptor. The results show an α2β1-independent pathway of platelet activation by CRP that involves phosphorylation of syk and PLCγ2. This pathway appears to contribute to platelet activation by collagen.

FGFR3 Associates with and Tyrosine-Phosphorylates p90RSK2, Leading to RSK2 Activation That Mediates Hematopoietic Transformation

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 3722-3722
Author(s):  
Sumin Kang ◽  
Shannon Elf ◽  
Shaozhong Dong ◽  
Taro Hitosugi ◽  
Ailan Guo ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Tyrosine Phosphorylation ◽  
Tyrosine Kinases ◽  
Mapk Pathway ◽  
Critical Role ◽  
Ectopic Expression ◽  
Alpha Helix ◽  
Tail Region ◽  
Murine Bone Marrow

Abstract Dysregulation of receptor tyrosine kinase FGFR3 has been implicated to play a pathogenic role in a number of human hematopoietic malignancies and solid tumors. These include t(4;14) multiple myeloma associated with ectopic expression of FGFR3 and t(4;12)(p16;p13) acute myeloid leukemia associated with expression of a constitutively activated fusion tyrosine kinase TEL-FGFR3. We recently reported that FGFR3 directly tyrosine phosphorylates p90 Ribosomal S6 Kinase2(RSK2) at Y529, which consequently regulates RSK2 activation [Kang et al, Cancer Cell 2007 Sep;12(3):201–14]. Here we identified Y707 as an additional tyrosine site of RSK2 that is phosphorylated by FGFR3. Phosphorylation at Y707 contributes to RSK2 activation, through a putative disruption of the autoinhibitory αL-helix on the C-terminus of RSK2, unlike Y529 phosphorylation that facilitates ERK binding. To elucidate the role of tyrosine phosphorylation at Y707 induced by FGFR3 in RSK2 activation, we characterized the RSK2 mutants with single Y→A and Y→F substitutions at Y707. RSK2 Y707F demonstrated decreased kinase activity, suggesting substitution of Y707 attenuates activation of RSK2 induced by FGFR3. Tyrosine phosphorylation at Y529 by FGFR3 regulates RSK2 activation by facilitating inactive ERK binding, whereas substitution of Y707 in RSK2 does not similarly attenuate inactive ERK binding to RSK2. Phosphorylation at Y707 may regulate RSK2 activation by affecting the structure of the autoinhibitory C-terminal domain of RSK2 since the Y707 is localized at the C-terminal tail region which represents a conserved putative auto-inhibitory alpha helix. Since other tyrosine kinases including FGFR1 and Src also phosphorylate RSK2 at Y529 and Y707, tyrosine phosphorylation may be a general requirement for RSK2 activation through the ERK/MAPK pathway. Together, our current and previous findings represent a paradigm for tyrosine phosphorylation-dependent regulation of serine-threonine kinases. Moreover, we found that FGFR3 interacts with RSK2 through residue W332 in the linker region of RSK2, and that this association is required for FGFR3-dependent phosphorylation of RSK2 at Y529 and Y707, and subsequent RSK2 activation. Furthermore, in a murine bone marrow transplant assay, genetic deficiency in RSK2 resulted in a significantly delayed and attenuated myeloproliferative syndrome induced by TEL-FGFR3 as compared with wild type cells, suggesting a critical role of RSK2 in FGFR3-induced hematopoietic transformation.

Sign in / Sign up

Export Citation Format

Share Document