A proliferation switch for genetically modified cells

Abstract

Receptor dimerization is the key signaling event for many cytokines, including erythropoietin. A system has been recently developed that permits intracellular protein dimerization to be reversibly activated in response to a lipid-soluble dimeric form of the drug FK506, called FK1012. FK1012 is used as a pharmacological mediator of dimerization to bring together FK506 binding domains, taken from the endogenous protein FKBP12. In experiments reported herein, FK1012-induced dimerization of a fusion protein containing the intracellular portion of the erythropoietin receptor allowed cells normally dependent on interleukin 3 to proliferate in its absence. FK506 competitively reversed the proliferative effect of FK1012 but had no inf luence on the proliferative effect of interleukin 3. Signaling pathways activated by FK1012 mimicked those activated by erythropoietin, because both JAK2 and STAT5 were phosphorylated in response to FK1012. This approach may provide a means to specifically and reversibly stimulate the proliferation of genetically modified cell populations in vitro or in vivo.

Protein‐protein interactions as a target for drugs in proteomics

“…At present these systems are used only in the laboratory. Dimerizers can induce cell proliferation [124], transcription [118,121] and apoptosis [121,123]. It is proposed to use these systems in gene therapy.…”

“…It is proposed to use these systems in gene therapy. Potentially, in clinical practice dimerizers can be used for induction of cell proliferation [124], or for elimination of the transferred gene product and genetically modified cells by dimerizer-inducing apoptosis [121,123].…”

Development of a modified selective amplifier gene for hematopoietic stem cell gene therapy

“…We have proposed a novel concept of 'selective amplifier genes' to confer a direct growth advantage on the target cells in response to exogenous stimuli. As a similar system to our GCRER chimeric receptors, Blau et al 23 reported that cytokine receptor-FKBP12 fusion genes conferred inducible proliferation on transfected Ba/F3 cells. 24 Their system involves synthetic dimerizers such as FK1012, of which short half lives and potential interactions with cellular immunophilins may be problematic in clinical use.…”

In vivo selective expansion of gene-modified hematopoietic cells in a nonhuman primate model

“…Some groups developed selective amplifier genes or cell growth switches, which are chimeric genes expressing a fusion protein composed of a growth factor receptor signaling domain and its specific molecular switch. 18,19 Blau et al developed cell growth switches that are cytokine receptor-FK506 binding protein (FKBP) fusion genes to confer inducible proliferation to transduced cells. 19,20 In their system, cytokine receptor signaling is turned on by treatment with a synthetic dimerizer FK1012 or its derivatives.…”

“…18,19 Blau et al developed cell growth switches that are cytokine receptor-FK506 binding protein (FKBP) fusion genes to confer inducible proliferation to transduced cells. 19,20 In their system, cytokine receptor signaling is turned on by treatment with a synthetic dimerizer FK1012 or its derivatives. Although the original FK1012 is complicated by its potential interactions with endogenous FKBPs leading to immunosuppression of recipients, its derivatives (AP1903, AP20187 etc) have been designed to reduce this interaction.…”