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Title: Tyrosine 192 within the SH2 domain of the Src‑protein tyrosine kinase p56Lck regulates T‑cell activation independently of Lck/CD45 interactions
Author(s): Kästle, Matthias
Merten, Camilla
Hartig, Roland
Kaehne, Thilo
Liaunardy-Jopeace, Ardiyanto
Woessner, Nadine M.Look up in the Integrated Authority File of the German National Library
Schamel, WolfgangLook up in the Integrated Authority File of the German National Library
James, John
Minguet, SusanaLook up in the Integrated Authority File of the German National Library
Simeoni, Luca
Schraven, BurkhartLook up in the Integrated Authority File of the German National Library
Issue Date: 2020
Type: Article
Language: English
URN: urn:nbn:de:gbv:ma9:1-1981185920-845859
Subjects: Lck
T-cell activation
TCR signaling
Knock-in mice
Signal transduction
Abstract: Background: Upon engagement of the T-cell receptor (TCR), the Src-family protein tyrosine kinase p56Lck phosphorylates components of the TCR (e.g. the TCRζ chains), thereby initiating T-cell activation. The enzymatic activity of Lck is primarily regulated via reversible and dynamic phosphorylation of two tyrosine residues, Y394 and Y505. Lck possesses an additional highly conserved tyrosine Y192, located within the SH2 domain, whose role in T-cell activation is not fully understood. Methods: Knock-in mice expressing a phospho-mimetic (Y192E) form of Lck were generated. Cellular and biochemical characterization was performed to elucidate the function of Y192 in primary T cells. HEK 293T and Jurkat T cells were used for in vitro studies. Results: Co-immunoprecipitation studies and biochemical analyses using T cells from LckY192E knock-in mice revealed a diminished binding of LckY192E to CD45 and a concomitant hyperphosphorylation of Y505, thus corroborating previous data obtained in Jurkat T cells. Surprisingly however, in vitro kinase assays showed that LckY192E possesses a normal enzymatic activity in human and murine T cells. FLIM/FRET measurements employing an LckY192E biosensor further indicated that the steady state conformation of the LckY192E mutant is similar to Lckwt. These data suggest that Y192 might regulate Lck functions also independently from the Lck/CD45-association. Indeed, when LckY192E was expressed in CD45−/−/ Csk−/− non-T cells (HEK 293T cells), phosphorylation of Y505 was similar to Lckwt, but LckY192E still failed to optimally phosphorylate and activate the Lck downstream substrate ZAP70. Furthermore, LckY19E was recruited less to CD3 after TCR stimulation. Conclusions: Taken together, phosphorylation of Y192 regulates Lck functions in T cells at least twofold, by preventing Lck association to CD45 and by modulating ligand-induced recruitment of Lck to the TCR.
Open Access: Open access publication
License: (CC BY 4.0) Creative Commons Attribution 4.0(CC BY 4.0) Creative Commons Attribution 4.0
Sponsor/Funder: Projekt DEAL 2020
Journal Title: Cell communication and signaling
Publisher: Biomed Central
Publisher Place: London
Volume: 18
Issue: 2020
Original Publication: 10.1186/s12964-020-00673-z
Page Start: 1
Page End: 18
Appears in Collections:Medizinische Fakultät (OA)

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