Type I gamma phosphatidylinositol phosphate 5-kinase i5 controls cell sensitivity to interferon.

The interferon signaling pathway is critical for host defense by serving diverse functions in both innate and adaptive immune responses. Here, we show that type I gamma phosphatidylinositol phosphate 5-kinase i5 (PIPKIγi5), an enzyme that synthesizes phosphatidylinositol-4,5-bisphosphate (PI4,5P2), controls the sensitivity to interferon in both human and mouse cells. PIPKIγi5 directly binds to the interferon-gamma (IFN-γ) downstream effector signal transducer and activator of transcription 1 (STAT1), which suppresses the STAT1 dimerization, IFN-γ-induced STAT1 nuclear translocation, and transcription of IFN-γ-responsive genes. Depletion of PIPKIγi5 significantly enhances IFN-γ signaling and strengthens an antiviral response. In addition, PIPKIγi5-synthesized PI4,5P2 can bind to STAT1 and promote the PIPKIγi5-STAT1 interaction. Similar to its interaction with STAT1, PIPKIγi5 is capable of interacting with other members of the STAT family, including STAT2 and STAT3, thereby suppressing the expression of genes mediated by these transcription factors. These findings identify the function of PIPKIγi5 in immune regulation.

Phosphoinositide Signaling in Immune Cell Migration.

In response to different immune challenges, immune cells migrate to specific sites in the body, where they perform their functions such as defense against infection, inflammation regulation, antigen recognition, and immune surveillance. Therefore, the migration ability is a fundamental aspect of immune cell function. Phosphoinositide signaling plays critical roles in modulating immune cell migration by controlling cell polarization, cytoskeletal rearrangement, protrusion formation, and uropod contraction. Upon chemoattractant stimulation, specific phosphoinositide kinases and phosphatases control the local phosphoinositide levels to establish polarized phosphoinositide distribution, which recruits phosphoinositide effectors to distinct subcellular locations to facilitate cell migration. In this Special Issue of "Molecular Mechanisms Underlying Cell Adhesion and Migration", we discuss the significance of phosphoinositide production and conversion by phosphoinositide kinases and phosphatases in the migration of different types of immune cells.

A triad of telomerase, androgen receptor and early growth response 1 in prostate cancer cells.

Telomerase activation is one of the key mechanisms that allow cells to bypass replicative senescence. Telomerase activity is primarily regulated at the level of transcription of its catalytic unit- hTERT. Prostate cancer (PCa), akin to other cancers, is characterized by high telomerase activity. Existing data suggest that hTERT expression and telomerase activity are positively regulated by androgenic stimuli in androgen-dependent prostate cancer (ADPC) cells. A part of the present study reaffirmed this by demonstrating a decline in the hTERT expression and telomerase activity on "loss of AR" in ADPC cells. The study further addressed 2 unresolved queries, i) whether AR-mediated signaling is of any relevance to hTERT expression in castration-resistant prostate cancer (CRPC) and ii) whether this signaling involves EGR1. Our data suggest that AR-mediated signaling negatively regulates hTERT expression in CRPC cells. Incidental support for the possibility of EGR1 being a regulator of hTERT expression in PCa was provided by i) immunolocalization of hTERT and EGR1 proteins in the same cell type (secretory epithelium) of PCa and BPH tissues; ii) significantly (p< 0.001) higher levels of both these proteins in CRPC (PC3 and DU145), compared with ADPC (LNCaP) cells. A direct evidence for the role of EGR1 in hTERT expression was evident by a significant (p<0.0001) decrease in the hTERT transcript levels in the EGR1-silenced CRPC cells. Further, "gain of AR" led to a significant reduction in the levels of hTERT and EGR1 in CRPC cells. However, restoration of EGR1 levels prevented the decline in the hTERT transcript levels in these cells. Taken together, our data indicate that AR regulates the expression of EGR1, which in turn acts as a positive regulator of hTERT expression in CRPC cells. Thus, AR exerts an inhibitory effect on hTERT expression and telomerase activity by modulating EGR1 levels in CRPC cells.

Proliferation and decidualization of endometrial stromal cells during embryo-attachment stage in bonnet monkeys (Macaca radiata).

We report embryo-induced alterations occurring in endometrial stromal cells (ESCs) during the embryo-attachment stage in bonnet monkeys (Macaca radiata). Laser micro-dissected ESCs obtained from pregnant and non-pregnant animals were compared for levels of selected proliferation and decidualization-associated factors by analysis with quantitative real-time polymerase chain reaction or immunohistochemistry. Stromal cells exhibited extensive cellular proliferation, as indicated by cellular compaction and significantly higher (P < 0.05) levels of proliferating cell nuclear antigen and of estrogen receptor 1, c-Myc, and Cyclin D1 transcripts in pregnant animals as compared with non-pregnant animals. A significant decrease (P < 0.05) was observed in the transcript levels of stromal interleukin-6 (IL-6) in pregnant animals. Cell proliferation was accompanied by a significant increase (P < 0.001) in the levels of decidualization-associated molecules such as IL-1ß in the luminal and glandular epithelium and of stromal insulin-like growth-factor-binding protein-1 (IGFBP-1) and prostaglandin-endoperoxide synthase-2 (PTGS-2) proteins. In pregnant animals, proliferation was evident throughout the gestational stroma, whereas decidualization was more pronounced in the embryo-attachment zone than in the non-attachment zone. To our knowledge, this is the first report of alterations in the endometrial stroma during the embryo-attachment stage in a non-human primate model.

Endometrial receptivity: a revisit to functional genomics studies on human endometrium and creation of HGEx-ERdb.

BACKGROUND: Endometrium acquires structural and functional competence for embryo implantation only during the receptive phase of menstrual cycle in fertile women. Sizeable data are available to indicate that this ability is acquired by modulation in the expression of several genes/gene products. However, there exists little consensus on the identity, number of expressed/not-detected genes and their pattern of expression (up or down regulation). METHODS: Literature search was carried out to retrieve the data on endometrial expression of genes/proteins in various conditions. Data were compiled to generate a comprehensive database, Human Gene Expression Endometrial Receptivity database (HGEx-ERdb). The database was used to identify the Receptivity Associated Genes (RAGs) which display the similar pattern of expression across different investigations. Transcript levels of select RAGs encoding cell adhesion proteins were compared between two human endometrial epithelial cell lines; RL95-2 and HEC-1-A by quantitative real time polymerase chain reaction (q-RT-PCR). Further select RAGs were investigated for their expression in pre-receptive (n = 4) and receptive phase (n = 4) human endometrial tissues by immunohistochemical studies. JAr spheroid attachment assays were carried out to assess the functional significance of two RAGs. RESULTS: HGEx-ERdb (http://resource.ibab.ac.in/HGEx-ERdb/) helped identification of 179 RAGs, of which 151 genes were consistently expressed and upregulated and 28 consistently not-detected and downregulated in receptive phase as compared to pre-receptive phase. q-RT-PCR confirmed significantly higher (p<0.005) expression of Thrombospondin1 (THBS1), CD36 and Mucin 16 transcripts, in RL95-2 as compared to HEC-1-A. Further, the pretreatment with antibodies against CD36 and COMP led to a reduction in the percentage of JAr spheroids attached to RL95-2. Immunohistochemical studies demonstrated significantly higher (p<0.05) expression of endometrial THBS1, Cartilage Oligomeric Matrix Protein (COMP) and CD36 in the receptive phase as compared to pre-receptive phase human endometrial tissues. CONCLUSION: HGEx-ERdb is a catalogue of 19,285 genes, reported for their expression in human endometrium. Further 179 genes were identified as the RAGs. Expression analysis of some RAGs validated the utility of approach employed in creation of HGEx-ERdb. Studies aimed towards defining the specific functions of RAGs and their potential networks may yield relevant information about the major 'nodes' which regulate endometrial receptivity.