Identification of a novel phosphoserine site on CrkL regulated by interleukin-2 and protein phosphatase-1
CrkL, a 36 kD adaptor protein, is part of the Crk family of proteins which have been implicated in a variety of human malignancies. CrkL is of special interest in hematopoietic malignancies because of an increased level of expression in myeloid and lymphoid derived cells lines. CrkL remains understudied but it has been shown to interact with Bcr-Abl in chronic myelogenous leukemia (CML) and is currently being used as a prognostic marker for patients by evaluating phosphorylation levels. Though regulation of CrkL by tyrosine phosphorylation has been studied extensively, the role of serine and threonine phosphorylation in an IL-2 dependent has not been characterized. CrkL has been shown to respond to IL-2 stimulation in T lymphocytes but it’s role in the Jak/STAT signaling pathway has not been well defined. This research used radiolabeling and phosphoamino acid analysis to show increased levels of serine phosphorylation upon IL-2 stimulation. Mass spectrometry analysis was then performed to identify novel phosphorylated serine sites upon IL-2 stimulation and Calyculin A treatment. Sites were aligned to determine conservation among species and were chosen for site directed mutagenesis. Mutated CrkL will be characterized further in future studies. CrkL was shown to co-immunoprecipiate with protein phosphatase 1,PP1, through mass spectrometry analysis and was further shown by completing CrkL immunoprecipitations and PP1 immunoblots. The relationship between PP1 and CrkL is important because PP1 may serve as a regulator of CrkL through serine de phosphorylation.
Moreno, Stephanie, "Identification of a novel phosphoserine site on CrkL regulated by interleukin-2 and protein phosphatase-1" (2015). ETD Collection for University of Texas, El Paso. AAI1600333.