Heat shock factor 1 (HSF1) is associated with tissue?specific tumorigenesis in a number of mouse models, and has been used a as prognostic marker of cancer types, including breast and prostatic cancer. However, its role in human hepatocellular carcinoma (HCC) is not well understood. Using immunoblotting and immunohistochemical staining, it was identified that HSF1 and its serine (S) 326 phosphorylation, a biomarker of HSF1 activation, are significantly upregulated in human HCC tissues and HCC cell lines compared with their normal counterparts. Cohort analyses indicated that upregulation of the expression of HSF1 and its phospho?S326 is significantly correlated with HCC progression, invasion and patient survival prognosis (P<0.001); however, not in the presence of a hepatitis B virus infection and the expression of alpha-fetoprotein and carcinoembryonic antigen. Knockdown of HSF1 with shRNA induced the protein expression of tumor suppressor retinoblastoma protein, resulting in attenuated plc/prf5 cell growth and colony formation in vitro. Taken together, these data markedly support that HSF1 is a potential prognostic marker and therapeutic target for the treatment of HCC.
Osteoclast Inhibitory Lectin-related Protein 2 (OCILRP2) is a typical type II transmembrane protein and belongs to C-type lectin-related protein family. It is preferentially expressed in dendritic cells (DC), B lymphocytes, and activated T lymphocytes. Upon binding to its ligand, OCILRP2 can promote CD28-mediated co-stimulation and enhance T cell activation. However, the role of OCILRP2 in DC development and activation is unclear. In this report, we present evidence that recombinant protein OCILRP2-Fc inhibits the generation and LPS-induced maturation of murine bone marrow-derived dendritic cells (BMDCs) by downregulating the expression of CD11c, MHC-II, and co-stimulators CD80 and CD86. OCILRP2-Fc also reduces the capacity of BMDCs to take up antigens, activates T cells, and secret inflammatory cytokines such as IL-6, IL-12, and TNF-?. Additionally, we show that OCILRP2-Fc may cause the aforementioned effects through inhibiting NF-?B activation. Therefore, OCILRP2 is a new regulator of DC maturation and differentiation following TLR4 activation.
HPK1, a member of mammalian Ste20-like serine/threonine kinases, is lost in >95% pancreatic cancer through proteasome-mediated degradation. However, the mechanism of HPK1 loss has not been defined. The aims of this study are to identify the ubiquitin ligase and to examine the mechanisms that targets HPK1 degradation. We found that the CUL7/Fbxw8 ubiquitin ligase targeted HPK1 for degradation via the 26S proteasome. The ubiquitination of HPK1 required its kinase activity and autophosphorylation. Wild-type protein phosphatase 4 (PP4), but not the phosphatase-dead PP4 mutant, PP4-RL, inhibits the interaction of Fbxw8 with HPK1 and Fbxw8-mediated ubiquitination of HPK1. In addition, we showed that Thr355 of HPK1 is a key PP4 dephosphorylation site, through which CUL7/Fbxw8 ubiquitin ligase and PP4 regulates HPK1 stability. Knockdown of Fbxw8 restores endogenous HPK1 protein expression and inhibits cell proliferation of pancreatic cancer cells. Our study demonstrated that targeted degradation of HPK1 by the CUL7/Fbxw8 ubiquitin ligase constitutes a negative-feedback loop to restrain the activity of HPK1 and that CUL7/Fbxw8 ubiquitin ligase promotes pancreatic cancer cell proliferation. CUL7/Fbxw8 ubiquitin ligase-mediated HPK1 degradation revealed a direct link and novel role of CUL7/Fbxw8 ubiquitin ligase in the MAPK pathway, which plays a critical role in cell proliferation and differentiation.
We have identified a CD8?CXCR5? T cell that prevents the development of oviduct dilation following C. muridarum genital infection. Phenotypic studies show that CD8?CXCR5? cells express markers of T regulatory cells (FoxP3, CD25, and GITR) but do not express a necessary component of cytotoxic cells (perforin). Cxcr5?/? mice have significantly lower numbers of CD8? cells and lack the CD8?CXCR5? population while the total number of CD4? cells is equivalent between mouse strains. The transfer of CD8? splenocytes from WT mice reduces the oviduct dilation seen in Cxcr5?/? mice following C. muridarum infection. Future studies will investigate the mechanism by which this cell type regulates genital tract pathology.
Generation of robust cell-mediated immune responses at mucosal surfaces while reducing overall inflammation is a primary goal for vaccination. Here we report the use of a recombinant nanoparticle as a vaccine delivery platform against mucosal infections requiring T cell-mediated immunity for eradication.
Heat shock factor 4b has been found to be closely associated with postnatal lens development. It expresses in postnatal lens epithelial and secondary fiber cells and controls the expression of small heat shock proteins which are important for lens homeostasis. However, the signal pathways underlying Hsf4b are still not completely understood. Here we present that Hsf4b transcription activity is regulated by FGF2 a key growth factor that is involved in regulating lens development at multiple stages. FGF2 can promote Hsf4b nuclear-translocation and the expression of Hsp25 and ?B-crystallin, the key downstream targets of Hsf4b in the Hsf4b-reconstituted mouse hsf4-/- lens epithelial cells. Further study indicates that FGF2 can induce Hsf4b protein stabilization through ERK1/2-mediated posttranslational phosphorylation or sumoylation. Hsf4b can promote FGF2-induced morphology transition from lens epithelial cell to the fiber cell, and this morphology transition can be inhibited by ERK1/2 inhibitor U0126. Taken together, our data demonstrate that Hsf4b is a novel downstream transcription factor of FGF2, and its transcription activity is associated with FGF2-modulated lens epithelial cell-fiber cell transition.
Regulation of immune responses is critical for controlling inflammation and disruption of this process can lead to tissue damage. We reported that CXCL13 was induced in fallopian tube tissue following C. trachomatis infection. Here, we examined the influence of the CXCL13-CXCR5 axis in chlamydial genital infection.
Hsf4b, a key regulator of postnatal lens development, is subjected to posttranslational modifications including phosphorylation. However, the phosphorylation sites in Hsf4b and their biological effects on the transcription activity of Hsf4b are poorly understood. Here we examined 17 potential phosphorylation residues in Hsf4b with alanine-scanning assays and found that a T472A mutation diminished Hsf4b-mediated expression of Hsp25 and ?B-crystallin. In contrast, the phosphomimetic mutation of T472D enhanced their expression. Further investigation demonstrated that Hsf4b could interact with nuclear-transporter importin ?-1 and Hsc70 via amino acids 246-320 and 320-493, respectively. T472A mutation reduced Hsf4bs interaction with importin ?-1, while enhancing its interaction with Hsc70, resulting in Hsf4b cytosolic re-localization, protein instability and transcription activity attenuation. At the upstream, MEK6 was found to interact with Hsf4b and enhance Hsf4bs nuclear translocation and transcription activity, probably by phosphorylation at sites such as T472. Taken together, our results suggest that phosphorylation of Hsf4b at T472 by protein kinases such as MEK6 regulates Hsf4b interaction with the importin ?-1-Hsc70 complex, resulting in blockade of its nuclear translocation and transcriptional activity of Hsf4b.
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