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JAK-STAT Pathway Overview

The janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway plays a critical role in the signaling of a wide array of cytokines and growth factors leading to various cellular functions, including proliferation, growth, hematopoiesis, and immune response.1-2

The binding of cytokines and growth factors to their corresponding receptors activates JAK, which then phosphorylates the receptor and STAT proteins on specific tyrosine residues. STATs then dimerize, translocate to the nucleus, bind to the consensus DNA sequence of 5’-TT(N4–6)AA-3’ and initiate the transcription of target genes.1-2

Life Technologies offers antibodies, ELISAs, Luminex® multiplex assays and growth factors for key targets in the JAK signaling cascade.

 

 

    JAK-STAT Pathway

Find JAK-STAT signaling pathway primary antibodies, antibody pairs, ELISAs and Luminex® assays by protein

Intracellular Proteins Membrane Receptors Cytokine Proteins

Key JAK-STAT Pathway Targets

Four JAK family kinases, including JAK1, JAK2, JAK3, and TYK2, and seven STAT family members, including STAT1, STAT2, STAT3, STAT4, STAT5a, STAT5b, and STAT6, have been identified. JAK1, JAK2, and TYK2 appear to be ubiquitously expressed, while JAK3 expression is normally limited to lymphoid cells. The JAKs are structurally unique in having a C-terminal kinase domain (JH1) preceded by a pseudokinase domain (JH2), which lacks the catalytic activity but has a critical regulatory function. JAKs also have a Src homology 2 (SH2) domain and an N-terminal band four-point-one, ezrin, radixin, moesin (FERM) domain that is critical for mediating the association with cytokine receptors. STAT proteins contain a SH2 domain for dimerization and a DNA-binding domain. The amino acid sequence diversity and their tissue-specific distributions account for the diverse roles of STATs in response to extracellular cytokines.1-2 The JAK-STAT pathways are up-regulated by a vast array of cytokines/growth factors. One mechanism for negative regulation of JAK-STAT pathways is through suppresser of cytokine signaling (SOCS) proteins, which directly bind to and inactivate JAKs3, and protein inhibitors of activated STATs (PIAS) that bind to phosphorylated STAT dimers, preventing DNA binding.4

Abnormal constitutive activation of JAK-STAT pathways has been implicated in various cancers and immune disorders. For example, STAT3 is persistently activated in many tumors, including major carcinomas and some hematologic tumors.5 Activating mutations in JAK2 have been linked to leukemia. TEL-JAK2 fusion due to chromosomal translocation was identified in a small set of human T cell acute lymphoblast leukemia patients.6 The V617F mutation in the JH2 pseudo-kinase domain of JAK2 was found in a high percentage of patients with myeloproliferative disorders, including polycythaemia vera.7 Inhibitors of JAK-STAT pathways are currently being sought in the areas of oncology and immune disorders.

Recombinant Antibody

Recombinant Rabbit Monoclonal Antibody
(click to enlarge)

Flow cytometry of Jurkat cells labeled with rabbit anti-STAT4. Jurkat cells were fixed and permeabilized using FIX & PERM® reagents.

Cells were stained with (black trace) or without (blue trace) 0.5 μg anti-STAT4 followed by Alexa Fluor® 488 goat anti-rabbit Ig. Pre-incubation with immunogenic peptide decreased the signal (red trace).  Data were generated using a Novex® STAT4 ABfinity™ Recombinant Rabbit Monoclonal Antibody     (700185).

Recombinant Protein

Recombinant Protein

Expression of STAT5b (pY699) in TF-1 cells.    TF-1 cells were treated with IFN-α or IL-3, or left unstimulated.

Cell lysates were analyzed using the STAT5b [pY699] ELISA kit. Treatment with IFN-α or IL-3 results in activation of the JAK/STAT pathway, as seen by the upregulation of phosphorylated STAT5b. Data were generated using a Novex® IFN-α Pure Recombinant Protein (PHC4014).

ELISA Quantification

ELISA Quantification

Total ELISA kits make effective controls. Cell extracts were prepared and analyzed with the STAT5a [pY694] ELISA and STAT5a (Total) ELISA kits. 

Phosphorylation of STAT5a is increased in sodium vanadate-treated HEL cells, whereas the total level of STAT5a remains relatively constant in treated vs. untreated control, demonstrating the utility of the Total ELISA kits as controls.  Data were generated using a Novex®
STAT5a [pY694] ELISA Kit (KHO0761) and    
STAT5a (Total) ELISA Kit (KHO0751).

Events leading to STAT activation.

Events leading to STAT activation
(click to enlarge)
     Events leading to STAT activation. (A) Extracellular IFN (blue triangle) prior to binding to its receptor. (B) Upon binding, JAK kinases constitutively associated with the receptor subunits interact. The interacting JAK proteins activate one another by reciprocal tyrosine phosphorylation, and phosphorylate a tyrosine on two subunits contained in the receptor complex. These phosphorylated tyrosine residues provide paired docking sites for STAT via its SH2 domain (C). STAT, recruited to the receptor complex, is then phosphorylated at a tyrosine residue by the JAKs. This tyrosine phosphorylation promotes STAT homo and heterodimerization mediated by reciprocal phosphotyrosine SH2 domain interaction and the dissociation of the dimers from the receptor complex (D). The STAT dimer is then translocated to the cell nucleus, where they complex with other nuclear proteins and regulate gene expression by binding to promotors or other response elements on DNA.

Intracellular Proteins

Gene Symbol
BAX MAP1 SMAD6
BCL2 MAP3 SMAD7
CREBBP MYC SOCS1
CUL2 NFKB1 SOCS2
EP300 (p300) PIAS1 SOCS3
FOS PIK3C3 SP1
GRB2 PIK3CA STAT1
HRAS PIK3CB STAT2
ISGF3G (IRF9) PIK3CD STAT3
JAK1 PIK3R1 STAT4
JAK2 PTPN11 (Shp2) STAT5A
JAK3 RAF1 STAT5B
JUN RBX1 STAT6
KPNA1 (NPI-1) RELA (NFκB) SUMO1
MAP2K1 ROS1 SUMO2
MAP2K2 SMAD1 SUMO3
MAP2K3 SMAD2 THPO (TPO)
MAP2K4 SMAD3 UBB
MAP2K5 SMAD4 UBE21
MAP2K6 SMAD5  

Membrane Receptors

Gene Symbol
ALK F2R (Par1) KDR (CD309)
AXL (UFO) F2RL2 KIT (CD117)
BTK FGFR1 (CD331) MERTK
CD2 FGFR2 (CD332) MET
CD4 FGFR3 (CD333) MST1R (CD136)
CD80 FGFR4 (CD334) MUSK
CSF1R (CD115) FLT1 NGFR (CD27)1
CXCR4 (CD184) FLT3 (CD135) NTRK1
DDR2 FLT4 NTRK2
EGFR IFNAR1 NTRK3
EPHA1 IFNAR2 (CD118) PDGFRA (CD140a)
EPHA2 IFNGR1 (CD119) PDGFRB (CD140b)
EPHA3 IGF1R (CD221) PRLR
EPHA4 IL1R1 (CD121a) ROR2
EPHA5 IL2RA (CD25) TEK
EPHA7 IL2RG (CD132) TNFRSF10A (CD120a)
EPHA8 IL3RA (CD123) TNFRSF10B (CD262)
EPHB1 IL4R (CD124) TNFRSF1A (CD120a)
EPHB2 IL6R (CD126) TNFRSF1B (CD120b)
EPHB3 IL12BR TNFRSF25 (DR3)
EPHB4 IL13RA (CD213A1) TYRO3
ERBB2 (Her2) INSR (CD220)  
ERBB4 (Her4) INSRR  

Cytokine Proteins

Gene Symbol
ANGPT1 FGF1 IL5
ANGPT2 FGF2 IL6
ANGPT4 FGF3 IL7
BMP2 FGF4 IL8
BMP7 FGF5 IL9
CCL2 (MCP1) FGF6 IL10
CCL3 (MIP-1α) FGF7 IL11
CCL4 (MIP-1β) FGF8 IL12A
CCL5 (RANTES) FGF9 IL12B
CCL7 (MCP-3) FGF10 IL13
CCL8 (MCP-2) FGF16 IL15
CCL11 (Eotaxin) FGF17 IL16
CCL13 (MCP4) FGF19 IL17A
CCL15 (MIP-5) GH1 IL18
CCL17 (TARC) IFNA1 IL19
CCL18 (MIP-4) IFNA2 IL20
CCL19 (MIP-3β) IFNB1 IL23A
CCL20 (MIP-3α) IFNG PRL
CCL21 (6Ckine) IL1A TNFSF10 (TRAIL)
CCL25 (TECK) IL1B TNFSF13B (BAFF)
CXCL12 (SDF1) IL2 VEGFA
EGF IL3 VEGFC
EPO IL4  

Technical Resources

 

References

  1. Aaronson, D.S. et al. (2002) Science 296: 1653-1655. 
  2. O’Shea, J.J. et al. (2004) Nat Rev Drug Discovery 3: 555-564.
  3. Kishimoto, T. et al. (2001) Nat Genetics 28: 4-5.
  4. Shuai, K. et al. (2000) Oncogene 19 : 2638-2645.
  5. Darnell, J.E. et al. (2005) Nat Medicine 11: 595-596.
  6. Lacronique, V. et al. (1997) Science 278: 1309-1312.
  7. Ferrajoli, A. et al. (2006) Curr Cancer Drug Targets 6: 671-679.

* This promotion is open to customers in the US and Canada. Discount will apply to orders received by Life Technologies no later than July 31, 2013, or until promotional supplies are depleted, whichever comes first. Customer can use the discount only once. Discount only applies to a maximum of 1 kit per customer. Discount applies to list price in effect at the time order is received by Life Technologies. Cannot be combined with other discounts or promotions. Offer void where prohibited, licensed, or restricted by federal, state, provincial, or local laws or regulation or agency/institutional policy. Other restrictions may apply.

For Research Use Only. Not intended for any animal or human therapeutic or diagnostic use.

 

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