Interaction of Human Suppressor of Cytokine Signaling (SOCS)-2 with the Insulin-like Growth Factor-I Receptor*
- From the ‡Metabolism Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892 and the ¶Strong Children’s Research Center, Department of Pediatrics, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642
Abstract
SOCS (suppressor of cytokine signaling) proteins have been shown to be negative regulators of cytokine receptor signaling via the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway. We have cloned a member of this family (hSOCS-2) by utilizing the insulin-like growth factor I receptor (IGF-IR) cytoplasmic domain as bait in a yeast two-hybrid screen of a human fetal brain library. The hSOCS-2 protein interacted strongly with the activated IGF-IR and not with a kinase negative mutant receptor in the two-hybrid assay. Mutation of receptor tyrosines 950, 1250, 1251, and 1316 to phenylalanine or deletion of the COOH-terminal 93 amino acids did not result in decreased interaction of the receptor with hSOCS-2 protein. hSOCS-1 protein also interacted strongly with IGF-IR in the two-hybrid assay. Glutathione S-transferase-hSOCS-2 associated with activated IGF-IR in lysates of mouse fibroblasts overexpressing IGF-IR. Human embryonic kidney cells (293) were transiently transfected with vectors containing IGF-IR and FLAG epitope-tagged hSOCS-2. After IGF-I stimulation, activated IGF-IR was found in anti-FLAG immunoprecipitates and, conversely, FLAG-hSOCS-2 was found in anti IGF-IR immunoprecipitates. Thus, hSOCS-2 interacted with IGF-IR both in vitro and in vivo. HSOCS-2 mRNA was expressed in many human fetal and adult tissues with particularly high abundance in fetal kidney and adult heart, skeletal muscle, pancreas, and liver. These results raise the possibility that SOCS proteins may also play a regulatory role in IGF-I receptor signaling.
Footnotes
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↵* This work was supported in part by research grants from Genentech Foundation for Growth and Development and National Institutes of Health Grant 1RO1 DK51657 (to R. W. F.).The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
The nucleotide sequence reported in this paper for hSOCS-2 has been submitted to GenBank with accession number AF037989.
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↵§ To whom correspondence should be addressed. National Institutes of Health, Bldg. 10, Rm. 4N115, Bethesda, MD 20892. Tel: 301-496-6340; Fax: 301-496-9956; E-mail: spniss{at}box-s.nih.gov.
- Abbreviations:
- JAK
-
Janus kinase
- SOCS
-
suppressor of cytokine signaling
- CIS
-
cytokine inducible SH2-containing protein
- SSI
-
STAT-induced STAT inhibitor
- AD
-
activation domain
- IGF
-
insulin-like growth factor
- IGF-IR
-
insulin-like growth factor-I receptor
- GST
-
glutathioneS-transferase
- STAT
-
signal transducer and activator of transcription
- PAGE
-
polyacrylamide gel electrophoresis
- EGF
-
epidermal growth factor
- IL
-
interleukin
- EPO
-
erythropoietin
- PCR
-
polymerase chain reaction
- RACE
-
rapid amplification of cDNA ends
- kb
-
kilobase(s)
- SH2
-
Src homology domain 2.
-
- Received May 12, 1998.
- The American Society for Biochemistry and Molecular Biology, Inc.
