Sidney Pestka, M.D.

Sidney Pestka, M.D.

Chairman and Professor
Office: (732) 235-4567
Fax: (732) 235-5223
pestkaumdnj.edu

Office:
RWJMS 736
Lab:
RWJMS 8th Floor

For the past two decades, interferon research has been a major focus of the laboratory. The research has led to the isolation, purification and characterization of the alpha, beta and gamma interferons, and subsequently their cloning and expression in bacteria. Interferons developed in the laboratory are currently available as approved therapeutics in the United States and worldwide for the treatment of various malignancies and viral diseases. During the past year, members of the laboratory have continued our endeavors to understand the interferons and their receptors, and to use these potent cytokines and immunomodulators to develop new strategies for the treatment and diagnosis of various diseases. The efforts have led to a number of new paths and unexpected directions many of which are described in this summary.

Differences in Receptor Interactions of Type I (IFN-α, IFN-β and IFN-ω) Human Interferons. Chinese hamster ovary (CHO) cells expressing the two chains, Hu-IFN-αR1 and Hu-IFN-αR2, of the Type 1 interferon receptor respond to all Type I human interferons including IFN-α, IFN-β and IFN-ω. A splice variant of the Hu-IFN-αR1 chain, designated Hu-IFN-αR1s, was also isolated and used to reconstitute CHO cells. With these cells, Cook, Cleary, Mariano, and Izotova identified two Type I interferons which can interact with the splice variant (Hu-IFN-αR1s) and with the Hu-IFN-αR1 chains: Hu-IFN-αA and IFN-ω. Two other Type I interferons, Hu-IFN-αB2 and Hu-IFN-αF, are capable of signaling through the complete Hu-IFN-αR1 chain only, but cannot utilize the splice variant Hu-IFN-αR1s. Hu-IFN-αR1 and Hu-IFN-αR1s differ in that the latter is missing a single subdomain of the receptor extracellular domain encoded by exons 4 and 5 of the Hu-IFN-αR1 gene. Therefore, different Type I interferons require different subdomains of the Hu-IFN-αR1 receptor chain and the splice variant chain discovered (Hu-IFN-αR1s) is functional. Because only one human recombinant interferon (IFN-αA, also called IFN-α2) is used in therapy, these results have implications for introducing additional human interferons for therapeutic use as they may have different therapeutic and side-effect profiles because they interact with the receptors differently.

The Interferon Gamma Receptor (IFN-γR) Complex. Each cytokine which utilizes the Jak-Stat signal transduction pathway activates a distinct combination of members of the Jak and Stat families. Thus, either the Jaks, the Stats or both could contribute to the specificity of ligand action. With the use of chimeric receptors involving the interferon gamma receptor (IFN-γR) complex as a model system, we demonstrated that Jak2 activation is not an absolute requirement for IFNγ signaling. Other members of the Jak family can functionally substitute for Jak2. IFN-γ can signal through the activation of Jak family members other than Jak2 as measured by Statl homodimerization and MHC class I antigen expression. This indicates that Jaks are interchangeable in the Jak-Stat signal transduction pathway and that the Jaks do not contribute to the specificity of signal transduction in the Jak-Stat pathway. During these experiments an orphan receptor, CRFB4, was discovered to have an intracellular domain with functional activity. These studies also demonstrated that only the long form of the IFN-α receptor chain 2 (IFN-αR2C) was functional in enabling the Type I interferon complex to respond to Type I interferons. Our results with chimeric receptors demonstrate how chimeric receptors can be used to determine the function of receptors and have permitted us to discover a new functional receptor chain, CRFB4.