Related Experiment Video

Updated: May 28, 2026

Protein Purification-free Method of Binding Affinity Determination by Microscale Thermophoresis
10:22

Protein Purification-free Method of Binding Affinity Determination by Microscale Thermophoresis

Published on: August 15, 2013

Characterization of a Cytokine-Independent STAT5 Activator

Grace A Aleck1,2, Yena Jin1, Zehui Gu1

  • 1Department of Pharmacology, University of Michigan, Ann Arbor, MI 48109, USA.

Biomedicines
|May 27, 2026
PubMed

Insights

Engineered STAT5 activators can bypass cytokine dependence to enhance immune cell survival and function. This approach shows promise for immune cell therapies in chronic diseases.

Area of Science:

  • Immunology
  • Molecular Biology
  • Cell Biology

Background:

  • Janus kinase-Signal transducer and activator of transcription (JAK-STAT) signaling is crucial for immune function but dysregulated in diseases like cancer and autoimmunity.
  • Activating STAT proteins independently of cytokines could improve immune cell persistence and efficacy in diseased tissues.

Purpose of the Study:

  • To characterize the interactome of a novel, engineered cytokine-independent STAT5 activator (aSTAT5).
  • To assess the ability of aSTAT5 to induce STAT5 activation in various immune cells, including primary human CD8+ T cells.
  • To evaluate the functional impact of aSTAT5-mediated STAT5 activation on immune cell survival and function.

Main Methods:

  • Proteomics, specifically affinity purification mass spectrometry (AP-MS), was used to define the aSTAT5 interactome and binding specificity.
  • STAT5 phosphorylation was measured in hematopoietic cell lines (NK-92, Jurkat, Raji B, RAW 264.7) and primary human CD8+ T cells.
  • Cell viability and cytotoxic function assays were performed under cytokine-deprived conditions.

Main Results:

  • Proteomic analysis confirmed aSTAT5 preferentially binds STAT5.
  • aSTAT5 induced robust STAT5 phosphorylation in LCK-expressing NK-92 and Jurkat T cells, but not in Raji B cells or RAW 264.7 macrophages.
  • Cytokine-independent STAT5 activation by aSTAT5 enhanced NK-92 and CD8+ T cell viability and preserved CAR T cell function during cytokine withdrawal.

Conclusions:

  • The interactome of the engineered STAT5 activator aSTAT5 was successfully defined.
  • aSTAT5 demonstrates the capacity to activate STAT5 independently of cytokines, maintaining survival and function in human CD8+ T cells and NK-92 cells.
  • Engineered cytokine-independent STAT5 activation holds significant translational potential for advancing immune cell-based therapies.
Keywords:
CAR-TLCKNK cellSTAT5T cellT cell signalingcytokinekinase

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