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Minimal change disease (MCD), the most common idiopathic nephrotic syndrome in children, is characterized by proteinuria and loss of glomerular visceral epithelial cell (podocyte) ultrastructure. Lipopolysaccharide (LPS) and puromycin aminonucleoside (PAN) are used to study podocyte injury in models of MCD in vivo and in vitro. We hypothesized that LPS and PAN influence components of the innate immune system in podocytes such as the Toll-Like Receptor (TLRs), TLR adapter molecules, and associated cytokines. Our results show that cultured human podocytes constitutively express TLRs 1-6 and TLR-10, but not TLRs 7-9. LPS (25 μg/ml) or PAN (60 μg/ml) caused comparable derangement of the actin cytoskeleton in podocytes. Quantitative RT-PCR analysis show that LPS differentially up-regulated the expression of genes for TLRs (1 > 4 ≥ 2 > 3 > 6 > 5), the adapter molecule, MyD88, and transcription factor NF-κB within one hour. LPS also caused increased levels of IL-6, IL-8 and MCP1 without exerting any effect on TNF-α, IFN-α or TGF-β1 at 24 h. Immunofluorescence intensity analysis of confocal microscopy images showed that LPS induced a significant increase in nuclear translocation of NF-κB by 6 h. In contrast, PAN-induced only small changes in the expression of TLRs 2-6 that included a persistent increase in TLRs 2 and 5, a transient increase in TLR-4, and a gradual increase in TLRs 3 and 6 between 1 and 6 h. Correspondingly, it did not alter pro-inflammatory cytokine levels in podocytes. However, PAN induced a low but significant increase in NF-κB nuclear translocation within one hour that remained unchanged up to 6 h. In summary, these novel findings show that LPS, a known TLR-4 ligand, induced the gene expression of multiple TLRs with maximum effect on the expression of TLR-1 suggesting a loss of receptor selectivity and induction of receptor interactions in podocytes. A comparable derangement of the podocyte cytoskeleton and significant increase in the nuclear translocation of NF-κB by PAN suggest that disparate but complementary mechanisms may contribute to the development of podocytopathy in MCD.

Using TLR pathways, primary human cytomegalovirus (HCMV) induces innate responses including the production of inflammatory cytokines. Mounting evidence suggests that LPS recognition by TLR4/MD2/CD14 results in differential utilization of TIRAP-TRAF6 and TRAM-TRIF signaling, thereby leading to transcriptional activation of various cytokine genes. However, relative roles of the TLR4/MD2/CD14 complex and its adaptor proteins TIRAP and TRAM involved in regulating monocyte responses to HCMV are incomplete. Here, we provided evidence supporting the notion that the TLR4/MD2/CD14 complex contributes notably to HCMV-induced signaling and subsequent cytokine production in monocytes. In particular, induction of both IL-6 and IL-8 is associated with elevated TIRAP and reduced TRAM mRNA expression. The latter may serve in a compensatory pathway that yields a robust IFN response when TIRAP signaling is blocked in monocytes incubated with Toledo strain HCMV. Inhibitory studies using antisense oligonucleotides or neutralizing antibodies indicate that IL-6 induction by TLR4/MD2 complex is important for the activation of endogenous CD14 which later acts in concert or synergy with TLR4/MD2 as a factor resulting in IL-8 gene expression. We further show that exogenous recombinant CD14 can potentiate innate immune response via TLR4-dependent and possibly via TLR9-dependent pathways to promote enhanced expression/production of IL-8 and IFN-β, respectively.

The differentiation of pancreatic exocrine AR42J cells into insulin-expressing endocrine cells has served as an important model for both endogenous in vivo ␤-cell differentiation as well as potential application to ␤-cell engineering of progenitor cells. Exogenous activin, possibly working through intracellular smad 2 and/or smad 3, as well as exogenous exendin-4 (a long-acting glucagon-like peptide-1 agonist) have both been shown to induce insulin-positive/endocrine differentiation in AR42J cells. In this study, we present evidence of significant interplay and interdependence of these two pathways as well as potential synergy between the pathways. In particular, insulin-positive differentiation seems to entail an exendin-4 -induced drop in smad 2 and elevation in smad 3 in RNA levels. The latter appears to be dependent on endogenous transforming growth factor (TGF)-␤ isoform release by the AR42J cells and may serve as a mechanism to promote ␤-cell maturation. The drop in smad 2 may mediate early endocrine commitment. The coapplication of exogenous exendin-4 and, specifically, low-dose exogenous TGF-␤1 led to a dramatic 20-fold increase in insulin mRNA levels, supporting a novel synergistic and codependent relationship between exendin-4 signaling and TGF-␤ isoform signaling. Diabetes 53: 2824 -2835, 2004 M echanisms underlying the differentiation of pancreatic precursor cells into insulin-positive cells are of paramount importance toward our goal of engineering cells to become glucose-responsive ␤-cells for the curative therapy of diabetes. Over the last several years, a well-validated model of such differentiation has been developed using rat AR42J pancreatic epithelial cells (1-3). Early reports used either activin, or activin in combination with hepatocyte growth factor or ␤-cellulin, to generate either endocrine (activin alone) or insulin-positive (activin in combination) cell lines. Activins are members of the transforming growth factor (TGF)-␤ superfamily that form hetero-or homodimers and bind specific type I and type II TGF-␤ superfamily receptors (4). In most cases, activin ligand signaling induces phosphorylation and activation of smad 2 and/or smad 3 transcription factors to initiate downstream signaling (5). Based on the above initial observations of the effects of activin, subsequent AR42J studies showed a potential role for intracellular smad signaling in mediating these activin-induced pathways. Early findings were that smad 2 was necessary for insulin-positive differentiation, but forced overexpression of smad 2 in AR42J cells was not sufficient to induce insulin-positive differentiation (6). More recently, given the incretin (insulin release) and insulinotrophic (insulin cell growth) effects of glucagon-like peptide-1 (GLP-1) (7-15), either GLP-1 protein or a long-acting form of GLP-1 (exendin-4) was used to induce an endocrine phenotype in AR42J cells. Here, multiple islet cell types were seen, with expression of cell-specific markers and the acquisition of an endocrine morphology in culture...

Distinctive genotypic and phenotypic features of ovarian cancer via epithelial-mesenchymal transition (EMT) have been correlated with drug resistance and disease recurrence. We investigated whether therapeutic reversal of EMT could re-sensitize ovarian cancer cells (OCCs) to existing chemotherapy. We report that epimorphin, a morphogenic protein, has pivotal control over mesenchymal versus epithelial cell lineage decision of the putative OCCs. Exposure to epimorphin induced morphological changes reminiscent of mesenchymal-to-epithelial transition (MET), but in a dose dependent manner, i.e., at 10 µg/mL of epimorphin cells obtain a more mesenchymal-like morphology while at 20 µg/mL of epimorphin cells display an epithelial morphology. The latter changes were accompanied by suppression of mesenchymal markers, such as vimentin (∼8-fold↓, p<0.02), Twist1 (∼7-fold↓, p<0.03), dystroglycan (∼4-fold↓, p<0.01) and palladin (∼3-fold↓, p<0.01). Conversely, significant elevations of KLF4 (∼28-fold↑, p<0.002), β-catenin (∼6-fold↑, p<0.004), EpCAM (∼6-fold↑, p<0.0002) and occludin (∼15-fold↑, p<0.004) mRNAs as part of the commitment to the epithelial cell lineage were detected in response to 20 µg/mL of exogenous epimorphin. Changes in occludin mRNA levels were accompanied by a parallel, albeit weaker expression at the protein level (∼5-fold↑, p<0.001). Likewise, acquisition of epithelial-like properties, including mucin1, CK19, and β-catenin gene expression, was also obtained following epimorphin treatment. Further, MMP3 production was found to be reduced whereas laminin secretion was strongly amplified upon epimorphin-induced MET. These results suggest there is a dosage window for actions of epimorphin on cellular differentiation, wherein it can either suppress or enhance epithelial differentiation of OCCs. Importantly, induction of epithelial-like phenotypes by epimorphin led to an enhanced sensitivity to carboplatin. Overall, we demonstrate that epimorphin can revert OCCs away from their mesenchymal phenotype and toward an epithelial phenotype, thereby enhancing their sensitivity to a front-line chemotherapeutic agent.

Summary. -Regulation of monocyte response to human cytomegalovirus (HCMV) occurs via activation of receptors that elicit innate antiviral effects and later T-cell responses. Our previous data (Yew et al.., 2010) demonstrated that human monocyte scavenger receptor A type 1 (SR-A1) are required for sensing of HCMV by endosomal toll-like receptors (TLRs)-3 and -9, which in turn induce critical pro-inflammatory cytokines. However, it remains unclear which subcellular molecules associated with SR-A1 lead to downstream activation of TLR-3 and/or TLR-9 signaling pathways. Herein we report that Lyn kinase, associated physically and functionally with SR-A for low density lipoprotein (LDL) recognition, acts as a key SR-A1-induced kinase that plays a critical role in TLR-3/9 signal transduction upon HCMV exposure to THP-1 monocytes. We found that disruption of the SR-A1 signal transduction through molecular inhibition by Lyn kinase oligonucleotides not only blocks the activation of downstream TLR-9 pathway but also alters the downstream TLR-3 pathway. In particular, Lyn kinase oligonucleotides resulted in decreased expression of TLR-9-induced tumor necrosis factor alpha (TNF-α) but strongly upregulated canonical TLR-3-induced interferon beta (IFN-β) and non-canonical TLR-3-induced NF-κB-dependent p35 (35kDa) subunit of interleukin 12 (IL-12p35) gene transcription. Thus, the observed shift away from TNF-α to robust IFN-β and IL-12p35 induction may offer opportunities for therapeutic interventions.Keywords: HCMV; THP-1 monocytes; TLR-3/-9; Lyn kinase; TNF-α; IFN-β; IL-12p35 E-mail: hyew@kumc.edu; fax: +816-983-6515. Abbreviations: HCMV = human cytomegalovirus; IFN-β = interferon beta; IL-12p35 = p35 (35 kDa) subunit of interleukin 12; IRF3 = interferon regulatory factor 3; LDL = low-density lipoproteins; MYD88 = myeloid differentiation primary response gene (88); NF-κB = nuclear factor kappa-light-chain-enhancer of activated B cells; SR-A1 = scavenger receptor A type 1; TLRs = toll-like receptors; TNF-α = tumor necrosis factor alpha; TRIF = TIR-domaincontaining adapter-inducing IFN-β

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