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Background: T-cell-mediated acute kidney transplant rejection (TCMR) is a post-transplantation complication characterized by the infiltration of immune cells into the tissue and sudden dysfunction of the allograft. To develop effective diagnostic and therapeutic methods, it is crucial to understand the molecular mechanisms involved in the initiation and progression of TCMR. Janus kinase (JAK) enzymes, which are involved in proinflammatory cytokine signal transduction, may play a role in TCMR. Given the recent development of JAK inhibitors, the role of JAK molecules should be explored to determine whether they could be potential targets for the treatment of TCMR. Objectives: The study aimed to compare the relative expression of JAK-1, JAK-2, and JAK-3 genes between patients diagnosed with TCMR and stable recipients. Methods: The expression of JAK-1, JAK-2, and JAK-3 genes was evaluated in peripheral blood monocytes of 30 patients with TCMR and 30 stable patients using the RT-PCR method. Results: Janus kinase-1 gene expression in TCMR patients was significantly higher compared to stable patients (P-value = 0.02). However, the relative expression of JAK-2 and JAK-3 genes was comparable between the two groups. Additionally, there was a negative correlation between JAK-1 and JAK-3 gene expression and the estimated glomerular filtration rate in the studied population (P-value = 0.01 and 0.029, respectively). Conclusions: Janus kinase-1 gene expression increased significantly during TCMR of the kidney transplant. Therefore, specific inhibition of this molecule by JAK inhibitor drugs might be considered a therapeutic option for treating TCMR. [ABSTRACT FROM AUTHOR]

Biallelic null or hypomorphic variants in JAK3 cause SCID and less frequently Omenn syndrome. We investigated homozygous hypomorphic JAK3 mutations in two patients, and expression and function of a novel JAK3R431P variant in Omenn syndrome. Immunophenotyping of PBMC from the patient with the novel JAK3R431P variant was undertaken, by flow cytometry and Phosflow after stimulation with IL-2, IL-7, and IL-15. JAK3 expression was investigated by Western blotting. We report two patients with homozygous hypomorphic JAK3 variants and clinical features of Omenn syndrome. One patient had a previously described JAK3R775H variant, and the second had a novel JAK3R431P variant. One patient with a novel JAK3R431P variant had normal expression of JAK3 in immortalised EBV-LCL cells but reduced phosphorylation of STAT5 after stimulation with IL-2, IL-7, and IL-15 consistent with impaired kinase activity. These results suggest the JAK3R431P variant to be hypomorphic. Both patients are alive and well after allogeneic haematopoietic stem cell transplantation. They have full donor chimerism, restitution of thymopoiesis and development of appropriate antibody responses following vaccination. We expand the phenotype of hypomorphic JAK3 deficiency and demonstrate the importance of functional testing of novel variants in disease-causing genes. [ABSTRACT FROM AUTHOR]

Background/Objectives: This subgroup analysis of the ALLEGRO phase 2b/3 trial (NCT03732807) evaluated the efficacy and safety of ritlecitinib, an oral, selective dual JAK3/TEC family kinase inhibitor, for the treatment of alopecia areata (AA) in patients aged 12–17 years. Methods: In ALLEGRO‐2b/3, patients aged ≥12 years with AA and ≥50% scalp hair loss received once‐daily ritlecitinib 50 or 30 mg (±4‐week 200‐mg loading dose) or 10 mg or placebo for 24 weeks. In a subsequent 24‐week extension period, ritlecitinib groups continued their doses, and patients initially assigned to placebo switched to 200/50 or 50 mg daily. Clinician‐ and patient‐reported hair regrowth outcomes and safety were assessed. Results: In total, 105 adolescents were randomized. At Week 24, 17%–28% of adolescents achieved a Severity of Alopecia Tool (SALT) score ≤20 (≤20% scalp without hair) in the ritlecitinib 30 mg and higher treatment groups versus 0% for placebo. At Week 48, 25%–50% of patients had a SALT score ≤20 across ritlecitinib treatment groups (30 mg and higher). Adolescents reporting that their AA "moderately" or "greatly" improved were 45%–61% in the ritlecitinib groups (30 mg and higher) (vs. 10%–22% for placebo) at Week 24 and 44%–80% at Week 48. The most common adverse events in adolescents were headache, acne, and nasopharyngitis. No deaths, major adverse cardiovascular events, malignancies, pulmonary embolisms, opportunistic infections, or herpes zoster infections were reported. Conclusion: Ritlecitinib treatment demonstrated clinician‐reported efficacy, patient‐reported improvement, and an acceptable safety profile through Week 48 in adolescents with AA with ≥50% scalp hair loss. [ABSTRACT FROM AUTHOR]

[Display omitted] • JAK3 promoter methylation was correlated with JAK3 expression in ccRCC. • JAK3 promoter methylation was associated with clinicopathological characteristics in ccRCC. • JAK3 promoter methylation was associated with overall survival in ccRCC. • JAK3 promoter methylation was correlated with immune cell infiltration in ccRCC. • JAK3 promoter methylation was correlated with the expression of immune checkpoint molecules in ccRCC. • JAK3 promoter methylation was a potential biomarker for predicting responses to immune checkpoint inhibitors in ccRCC. Janus kinase 3 (JAK3) is a well-established oncogene in clear cell renal cell carcinoma (ccRCC). The methylation status of oncogene promoters has emerged as biomarkers for cancer diagnosis and prognosis. This study aims to investigate the biological and clinical significance of JAK3 promoter methylation in ccRCC. We analyzed the relationship of JAK3 promoter methylation with its mRNA expression, overall survival, and immune cell infiltration in a cohort obtained from The Cancer Genome Atlas (TCGA), which was further validated by another independent cohort. We further validated correlations of JAK3 promoter methylation with JAK3 expression, overall survival, and immune cell infiltration in an independent ccRCC cohort (Sun Yat-sen University Cancer Center (SYSUCC) cohort) by methods of immunohistochemistry (IHC) and pyrosequencing. We found JAK3 promoter was significantly hypomethylated in tumor tissues compared to normal adjacent tissues in ccRCC, and JAK3 promoter hypomethylation was strongly correlated with high JAK3 mRNA expression in all three ccRCC cohorts we examined. JAK3 promoter hypomethylation predicted advanced clinicopathological characteristics and shorter overall survival (TCGA cohort and SYSUCC cohort). Furthermore, we found that JAK3 promoter methylation was significantly associated with immune cell infiltration and expression of immune checkpoint molecules (TCGA cohort and CPTAC cohort). Finally, our SYSUCC cohort validated that JAK3 promoter methylation was correlated with CD4+ and CD8+ T cell infiltration in ccRCC tumor tissues. Our data demonstrated that the crucial role of JAK3 promoter methylation in its expression regulation and tumor microenvironment. JAK3 promoter methylation and expression are associated with clinicopathological characteristics, overall survival, and immune cell infiltration in ccRCC. We propose a rationale for further validation of JAK3 promoter methylation as a molecular biomarker for predicting responses to immune checkpoint inhibitors in ccRCC. [ABSTRACT FROM AUTHOR]

JAK3 genetic mutations effects The Janus kinase-signal transducerand activator of transcription(JAK-STAT) pathway was supposedto be involved in the frequently alteredmechanism in HCC. Keywords: Hepatocellular carcinoma; Next generation sequencing (NGS); Janus kinase 3 EN Hepatocellular carcinoma Next generation sequencing (NGS) Janus kinase 3 Liver diseases are a significantcause of mortality and morbiditythroughout the world, causing twomillion deaths per year worldwide(3.5% of all death), with 50% relatedto cirrhosis complications and 50%associated with Hepatocellular Carcinoma(HCC) and viral hepatitis infections(Asrani et al., 2019). JAK3 mutations detected inthe current study might play a minimalrole in HCV-associated hepatocarcinogenesis.A study conducted by(Hin Tang et al., 2020) showed thatmany intracellular signaling pathwayscontribute to hepatocarcinogenesis,including the JAK/STAT pathway,which has normal roles in regulatingcell proliferation, survival, and differentiation. [Extracted from the article]

Introduction and hypothesis: As a notable chronic disorder, the incidence of interstitial cystitis (IC) has been documented to have increased among the female population with activity in microRNA-495 (miR-495) implicated in this disease. The current study was aimed at elucidating the effects associated with miR-495 on the inflammatory response and bladder fibrosis in rats with ulcerative IC via the JAK–STAT pathway by targeting JAK3. Methods: Ulcerative IC rat models were established. The targeting relationship between JAK3 and miR-495 was evaluated using luciferase reporter assay. After gain- or loss-of-function assays, mast-cell infiltration was assessed using toluidine blue staining, bladder fibrosis using Masson staining, and NO content using nitrate reductase method. JAK3 protein expression was detected by immunohistochemistry, JAK3, STAT1, STAT3, TGFβ-1, Col-I, Col-III, JAK1, JAK2, p-STAT1, and p-STAT3 expression by RT-qPCR and Western blot analysis, and serum IL-6, IL-8, IL-10, IL-17, and TNF-α levels in rats by ELISA. Results: Following transfection of overexpressed miR-495 or siRNA-JAK3, a diminished degree of mast-cell infiltration, number of mast cells, bladder fibrosis, NO content, JAK3-positive expression, mRNA expression of JAK3, STAT1, STAT3, TGFβ-1, Col-I, Col-III, protein expression of JAK1, JAK2, JAK3, p-STAT1, p-STAT3, and expression of IL-6, IL-8, IL-10, IL-17, and TNF-α were identified. Conclusions: Collectively, our key findings provide evidence supporting the notion that the overexpression of miR-495 ameliorates inflammatory response and bladder fibrosis in ulcerative IC rat models via inactivation of the JAK–STAT signaling pathway by inhibiting JAK3. [ABSTRACT FROM AUTHOR]

Cortistatin A is a natural product isolated from the marine sponge Corticium simplex has been considered as a therapeutic agent for autoimmune disorders, HIV infection as well as cancer. Janus kinases (JAKs) and signal transducer and activator of transcription (STAT) transcription factors play a promising role in either causing or participating in the tumorigenesis. Following our earlier studies on JAK-STAT pathway genes varied expression among the various types of breast cancer samples, JAK3 protein plays a crucial role in cancer pathway, thus we implement a feasible systems pharmacology method to explore JAK3 function. Our systematic Insilco approaches involve systems-based assessment of JAK3 role in cytokine signaling, ADMET a scale for pharmacokinetic and pharmacodynamics assessment, pharmacophore mapping of JAK3 and ligand Cortistatin A. Sequence level annotation of functional domains revealed similarity between the JAK family members namely JAK1, JAK2, JAK 3 and TYK2. Thus intermolecular interaction, molecular dynamics and simulation assessment of JAK3 with Cortistatin docked complex pattern applicable other members that shared the domain similarity. Thus, our present study proposes the system level of understanding about Cortistatin A agonist activity on JAK3 and suggesting the compound as a potent antiproliferative agent for cancer treatment. [ABSTRACT FROM AUTHOR]

In the present study, the mechanism by which carboxyl terminal activating region 3 (CTAR3) of latent membrane protein 1 (LMP1), encoded by the Epstein-Barr virus, regulated cell proliferation and protein expression was investigated in the nasopharyngeal epithelial cell line NP69. The deletion mutant LMP1 (LMP1Δ232-351; amino acid residues including 232–351 codons in CTAR3 deleted) was generated by polymerase chain reaction. An NP69-LMP1Δ232-351 cell line was established by retroviral infection. Finally, cell proliferation and protein expression of NP69 cells expressing LMP1Δ232-351 were examined using a cell growth curve and western blot analysis. The results demonstrated: i) The proliferation of NP69-LMP1Δ232-351 cells was significantly decreased compared with cells expressing wild type LMP1 (LMP1WT; n=3; P<0.05); ii) 17 proteins exhibited differential protein expression (>2-fold change) in NP69-LMP1Δ232-351 cells compared with NP69-LMP1WT cells; and iii) LMP1WT was involved in activating the Janus kinase 3 (JAK3) promoter and regulating the expression of JAK3 protein, while LMP1Δ232-351 was almost defective in ability to activate the JAK promoter. These results suggested that LMP1-CTAR3 may be an important functional domain for regulating cell proliferation and protein expression in nasopharyngeal epithelial cells. [ABSTRACT FROM AUTHOR]

Graphical abstract The two generated pharmacophore models (PBDD) were coupled with docking simulations (LBDD) to identify new compounds with dual JAK1 and JAK3 inhibitory activity. Highlights • Pharmacophore models of JAK1 and JAK3 were generated followed by rigorous validation. • Virtual screening through the generated molecules was carried out. • Molecular docking and molecular dynamics analysis was incorporated to confirm the interactions with respective enzymes. • ADME filter was done to eliminate the hits with poor pharmacokinetic profile. Abstract Janus kinase 1 and 3 are non-receptor protein tyrosine kinases, involved in the regulation of various cytokines implicated in the pathogenesis of autoimmune and inflammatory disease conditions. Thus, they serve as therapeutic targets for the designing of multi-targeted agents for the treatment of inflammatory-mediated pathological conditions. In the present study, diverse inhibitors of JAK1 and JAK3 were considered for the development of ligand-based pharmacophore models, followed by docking analysis to design putative dual inhibitors. The pharmacophore models were generated in PHASE 3.4, and top five models for each target were selected on the basis of survival minus inactive score. The best model for JAK1 (AAADH.25) and JAK3 (ADDRR.142) were selected corresponding to the highest value of Q2 test. Both models were employed for the screening of a PHASE database, and subsequently, the retrieved hits were filtered employing molecular docking in JAK1 and JAK3 proteins. The stable interactions between retrieved hits and proteins were confirmed using molecular dynamics simulations. Finally, ADME properties of screened dual inhibitors displaying essential interactions with both proteins were calculated. Thus, the new leads obtained in this way may be prioritized for experimental validation as potential novel therapeutic agents in the treatment of various autoimmune and inflammatory disorders related to JAK1 and JAK3. [ABSTRACT FROM AUTHOR]

Janus kinases (JAKs) are a family of four cytosolic protein kinases with a high degree of structural similarity. Due to its very restricted role in immune regulation, JAK3 was promoted as an excellent target for immunosuppression for more than a decade, but clinical validation of this concept is still elusive. During the last years, speculation arose that kinase activity of JAK1, which cooperates with JAK3 in cytokine receptor signaling, may have a dominant role over the one of JAK3. Until recently, however, this issue could not be appropriately addressed due to a lack of highly isoform-selective tool compounds. With the recent resurgence of covalent drugs, targeting of a specific cysteine that distinguishes JAK3 from other JAK family members became an attractive design option. By applying this strategy, a set of JAK3 inhibitors with excellent selectivity against other JAK isoforms and the kinome was developed during the last three years and used to decipher JAK3-dependent signaling. The data obtained with these tool compounds demonstrates that selective JAK3 inhibition is sufficient to block downstream signaling. Since one of these inhibitors is currently under evaluation in phase II clinical studies against several inflammatory disorders, it will soon become apparent whether selective JAK3 inhibition translates into clinical efficacy. [ABSTRACT FROM AUTHOR]

Severe combined immunodeficiency ( SCID) is the most severe form of primary immunodeficiency disease, and it is characterized by marked impairment in cellular and humoral immunity. Mutations in several genes cause SCID, one of which is Janus kinase 3 ( JAK3), resulting in autosomal recessive T(-)B(+) NK(-) SCID. Only three patients with JAK3-deficient SCID have been reported in Japan. We herein describe the case of a 6-month-old girl with pneumocystis pneumonia, who was diagnosed with SCID with compound heterozygous JAK3 mutations (c.1568G>A + c.421-10G>A). One of the mutations was previously reported in another Japanese patient. The other mutation was a novel and de novo relatively deep intronic mutation causing aberrant RNA splicing. The patient was successfully treated with bone marrow transplantation from a haploidentical donor. [ABSTRACT FROM AUTHOR]

Background/Aims: Oscillations of cytosolic Ca2+ activity ([Ca2+]i) participate in the orchestration of tumor cell proliferation. [Ca2+]i could be increased by intracellular Ca2+ release followed by store-operated Ca2+-entry (SOCE). [Ca2+]i could be decreased by Ca2+ extrusion via Na+/ Ca2+ exchange. Mechanisms accomplishing SOCE include the pore-forming ion channel unit Orai1 and its regulator STIM1, Na+/Ca2+ exchanger isoforms include NCX1. In MCF-7 breast carcinoma cells Orai1 and NCX1 have previously been shown to be modified by pharmacological inhibition of Janus activated kinase JAK2. The present study explored whether SOCE and Na+/ Ca2+ exchange are similarly sensitive to pharmacological JAK3 inhibition. Methods: MCF- 7 breast carcinoma cells were studied in the absence and presence of the JAK3 inhibitor WHI-P154 (22 μM). [Ca2+]i was estimated from Fura-2-fluorescence, SOCE from increase of [Ca2+]i following Ca2+ re-addition after Ca2+-store depletion with sarcoendoplasmatic Ca2+- ATPase (SERCA) inhibitor thapsigargin (1 μM), and Na+/Ca2+ exchanger activity from increase of [Ca2+]i following extracellular Na+ removal. Transcript levels were quantified with RT-PCR. Results: Addition of ATP (100 μM) was followed by a rapid increase of [Ca2+]i, which was significantly blunted by WHI-P154. Thapsigargin-induced intracellular Ca2+ release was not appreciably influenced by WHI-P154. Subsequent SOCE was, however, significantly blunted by WHI-P154. WHI-P154 further significantly decreased Orai1 transcript levels. The increase of [Ca2+]i following extracellular Na+-removal and the NCX1 transcript levels were similarly decreased by WHI-P154. Conclusions: The JAK3 inhibitor WHI-P154 decreases both, Orai1 and NCX1 transcript levels and thus impairs SOCE and Na+/Ca2+ exchange. [ABSTRACT FROM AUTHOR]

Background: The etiology of axial spondyloarthritis (axSpA) is not fully elucidated. Research continues in determining the mechanisms responsible for initiation of the disease process, its maintenance and development. Objectives: The aim of this study was to evaluate the expression of transcription factors STAT (signal transducer and activator of transcription) and NF-κB (nuclear factor kappa B) as well as Janus kinase3 (JAK3) in the peripheral blood leukocytes. We also analyzed the connection between the degree of activation of transcription factors and the disease activity. Material/Methods: The study involved 46 patients with axSpA and 19 healthy individuals who comprised the control group. The expression of NF-κB, STAT1, STAT3, STAT4, STAT5, STAT6, and JAK3 in peripheral blood leukocytes was assessed. To determine the degree of activation of transcription factors STAT-s and NF-κB and JAK3 kinase, the immunocytochemistry method was used. For location of the factors, the primary monoclonal anti-NF-κB, anti-JAK3 and polyclonal anti-STAT-s antibodies were used (Chemicon International, USA, Abcam, Cambridge, UK), and the set of antibodies Novocastain Super ABC Kit (Novocastra, UK). Results: Expression of STAT1, STAT3, STAT4, STAT5, STAT6, NF-κB and JAK3 was statistically higher in the group of patients with axSpA than in the control group. There was a positive correlation with ESR values and expression of STAT4. There was no correlation between STAT, NF-κB, and JAK3 expression and ASDAS, BASDAI, and BASFI. Nine patients were treated with TNF-α inhibitors. The expression of NF-κB and STAT6 was higher in the group treated with TNF-α inhibitors, even though disease activity in these patients was shown to be lower than in those not receiving such treatment (ASDAS = 1.34±0.51 vs. 3.52±0.90, BASDAI = 2.34±1.92 vs. 5.51±2.41). Conclusions: In the group of patients with axSpA compared with the control group, higher expression of the transcription factors STAT and NF-κB as well as JAK3 was observed. Due to its crucial roles in inflammation and autoimmunity, STAT4 may have promise as an effective therapeutic target for axSpA. [ABSTRACT FROM AUTHOR]

Janus kinase 3, a tyrosine kinase expressed in haematopoetic tissues, plays a decisive role in T-lymphocyte survival. JAK3 deficiency leads to (Severe) Combined Immunodeficiency (SCID) resulting from enhanced lymphocyte apoptosis. JAK3 is activated by phosphorylation. Nothing is known about expression of JAK3 in erythrocytes, which may undergo apoptosis-like cell death (eryptosis) characterized by cell membrane scrambling with phosphatidylserine exposure and cell shrinkage. Triggers of eryptosis include energy depletion. The present study utilized immunohistochemistry and confocal microscopy to test for JAK3 expression and phosphorylation, and FACS analysis to determine phosphatidylserine exposure (annexin binding) and cell volume (forward scatter). As a result, JAK3 was expressed in erythrocytes and phosphorylated following 24h and 48h glucose depletion. Forward scatter was slightly but significantly smaller in erythrocytes from JAK3-deficient mice (jak3-/-) than in erythrocytes from wild type mice (jak3+/+). Annexin V binding was similarly low in both genotypes. The JAK3 inhibitors WHI-P131/JANEX-1 (4-(4′-Hydroxyphenyl)amino-6,7-dimethoxyquinazoline, 156μM) and WHI-P154 (4-[(3′-Bromo-4′-hydroxyphenyl)amino]-6,7-dimethoxyquinazoline, 11.2μM) did not significantly modify annexin V binding or forward scatter. Glucose depletion increased annexin V binding, an effect significantly blunted in jak3-/- erythrocytes and in the presence of the JAK3 inhibitors. The observations disclose a completely novel role of Janus kinase 3, i.e. the triggering of cell membrane scrambling in energy depleted erythrocytes. Copyright © 2011 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Abstract: Janus kinase 3 (JAK3) is a non-receptor tyrosine kinase vital to the regulation of T-cells. We report that JAK3 is a mediator of interleukin-8 (IL-8) stimulation of a different class of hematopoietic relevant cells: human neutrophils. IL-8 induced a time- and concentration-dependent activation of JAK3 activity in neutrophils and differentiated HL-60 leukemic cells. JAK3 was more robustly activated by IL-8 than other kinases: p70S6K, mTOR, MAPK or PKC. JAK3 silencing severely inhibited IL-8-mediated chemotaxis. Thus, IL-8 stimulates chemotaxis through a mechanism mediated by JAK3. Further, JAK3 activity and chemotaxis were inhibited by the flavonoid apigenin (4′,5,7-trihydroxyflavone) at ∼5nM IC50. These new findings lay the basis for understanding the molecular mechanism of cell migration as it relates to neutrophil-mediated chronic inflammatory processes. [ABSTRACT FROM AUTHOR]

The principal Epstein–Barr virus (EBV) oncoprotein, latent membrane protein 1 (LMP1), has been suggested to contribute to the highly invasive nature of nasopharyngeal carcinoma (NPC). Signal transducer and activator of transcription 3 (STAT3) is a master transcriptional regulator in proliferation and apoptosis and is newly implicated in angiogenesis and invasiveness, which, in turn, are likely to contribute to the highly invasive character of NPC. The fundamental molecular mechanisms of LMP1-regulated STAT3 activation in NPC cell invasion have not been completely explored. Here, we showed that LMP1 signals the Janus kinase 3 (JAK3) and extracellular signal-regulated kinase 1/2 (ERK1/2) pathways upon the activation of STAT3 as well as STAT transactivation activity. LMP1 induces vascular endothelial growth factor (VEGF) expression via the JAK/STAT and mitogen-activated protein kinase (MAPK)/ERK signalling pathways. Induction of STAT3 by the human viral oncoprotein LMP1 may contribute to the invasion of NPC. [Copyright &y& Elsevier]

J. Neurochem. (2010) 113, 1210–1220. Retinal degeneration causes the induction of a leukemia inhibitory factor (LIF)-controlled survival pathway which includes Janus kinase/signal transducer and activator of transcription signaling. Lack of LIF prevents activation of this signaling cascade and accelerates disease progression leading to a fast loss of photoreceptor cells. In this study, we show that expression of Janus kinase 3 ( Jak3), but not of the other members of the family of Janus kinases, is induced in four different models of retinal degeneration and that LIF is essential and sufficient to activate Jak3 gene expression. We also show that the induction of Jak3 and Lif may not depend directly on cell death but rather on the retinal stress during photoreceptor degeneration. However, despite its dependence on LIF, JAK3 is not essential for LIF-mediated photoreceptor protection or gene expression. Also, absence of JAK3 in knockout mice did not affect immune-related responses in the degenerating retina. JAK3 may therefore play a different, yet unknown, role in the retinal response to photoreceptor injury. [ABSTRACT FROM AUTHOR]

Acquired mutations activating Janus kinase 3 (jak3) have been reported in Down syndrome (DS) and non-DS patients with acute megakaryoblastic leukaemia (AMKL). This highlighted jak3-activation as an important event in the pathogenesis of AMKL, and predicted inhibitors of jak3 as conceptual therapeutics for AMKL. Of 16 DS-transient myeloproliferative disorder (TMD)/AMKL patients tested, seven showed JAK3 mutations. Three mutations deleted the kinase (JH1) domain, abolishing the main function of jak3. Another patient displayed a mutation identical to a previously reported inherited loss-of-function causing severe combined immunodeficiency. Our data suggest that both gain-, and loss-of function mutations of jak3 can be acquired in DS-TMD/AMKL. [ABSTRACT FROM AUTHOR]

Janus kinase 3 (JAK3) mediates signal transduction from cytokine receptors using the common γ chain. The rationally designed inhibitor of JAK3, CP-690,550, prevents acute allograft rejection in rodents and in nonhuman primates. Here we investigated the ability of CP-690,550, to prevent allograft vasculopathy in a rodent model of aorta transplantation. Aortas from AxC Irish (RT1a) or Lewis (RT1l) rats were heterotopically transplanted into the infra-renal aorta of Lewis recipients and harvested at 28 or 56 days. Treated recipients received CP-690,550 by osmotic pumps (mean drug exposure of 110 ± 38 ng/ml). Significant intimal hyperplasia was demonstrated in untreated allografts when compared with isografts at 28 days (2.08 ± 0.85% vs. 0.43 ± 0.2% luminal obliteration, respectively, P = 0.001) and 56 days (5.3 ± 2.4% vs. 0.38 ± 0.3%, P = 0.002). Treatment caused a 51% reduction in intimal hyperplasia at day 56. CP-690,550-treated animals also had a significant reduction of donor-specific IgG production and of the gene expression for suppressor of cytokine signaling-3 and with unchanged levels of expression of RANTES, IP-10 and transforming growth factor- β1. These results are the first to show that JAK3 blockade by CP-690,550 effectively prevents allograft vasculopathy in this rat model of aorta transplantation. [ABSTRACT FROM AUTHOR]

Abstract: In this study, we applied commercially available cDNA microarray systems (1068 genes) to investigate the genetic changes in six colorectal cancers (CRC). Thirty-two genes fell into the group of commonly upregulated genes. In addition, we immunohistochemically investigated the expression of the four top ranked upregulated genes, Janus kinase 3 (JAK3), matrix metalloproteinase 13 (MMP13), heat shock protein 60 (HSP60), and mouse double minute 2 (MDM2), in 44 CRC. JAK3 staining was located in the cancer cells. A comparison of JAK3 immunostaining and clinicopathological parameters showed a significant association of tumor differentiation, pT, and TMN stage. Staining of MMP13 and HSP60 was noted mainly in the cytoplasm of cancer cells. A significant association of these expressions was observed with tumor differentiation and pT. MDM2 staining was noted in the nucleus of cancer and non-cancer cells. No significant association of clinicopathological parameters with MDM2 expression was observed. In multivariate analysis, JAK3 immunoreactivity showed independent prognostically unfavorable predictors. These data suggest that JAK3, in particular, is a highly significant, prognostic immunohistochemical marker in CRC. This study proves that cDNA microarrays, plotted by a small number of genes from a few samples, are both practical and useful. [Copyright &y& Elsevier]

The nonreceptor tyrosine TEC kinases are key regulators of the immune system and play a crucial role in the pathogenesis of diverse hematological malignancies. In contrast to the substantial efforts in inhibitor development for Bruton's tyrosine kinase (BTK), specific inhibitors of the other TEC kinases, including the bone marrow tyrosine kinase on chromosome X (BMX), remain sparse. Here we present a novel class of dual BMX/BTK inhibitors, which were designed from irreversible inhibitors of Janus kinase (JAK) 3 targeting a cysteine located within the solvent-exposed front region of the ATP binding pocket. Structure-guided design exploiting the differences in the gatekeeper residues enabled the achievement of high selectivity over JAK3 and certain other kinases harboring a sterically demanding residue at this position. The most active compounds inhibited BMX and BTK with apparent IC50 values in the single digit nanomolar range or below showing moderate selectivity within the TEC family and potent cellular target engagement. These compounds represent an important first step towards selective chemical probes for the protein kinase BMX. [ABSTRACT FROM AUTHOR]