Age-related Macular Degeneration (AMD), a blinding eye disease, is characterized by pathological protein- and lipid-rich drusen deposits underneath the retinal pigment epithelium (RPE) and atrophy of ...the RPE monolayer in advanced disease stages - leading to photoreceptor cell death and vision loss. Currently, there are no drugs that stop drusen formation or RPE atrophy in AMD. Here we provide an iPSC-RPE AMD model that recapitulates drusen and RPE atrophy. Drusen deposition is dependent on AMD-risk-allele CFH(H/H) and anaphylatoxin triggered alternate complement signaling via the activation of NF-κB and downregulation of autophagy pathways. Through high-throughput screening we identify two drugs, L-745,870, a dopamine receptor antagonist, and aminocaproic acid, a protease inhibitor that reduce drusen deposits and restore RPE epithelial phenotype in anaphylatoxin challenged iPSC-RPE with or without the CFH(H/H) genotype. This comprehensive iPSC-RPE model replicates key AMD phenotypes, provides molecular insight into the role of CFH(H/H) risk-allele in AMD, and discovers two candidate drugs to treat AMD.
Recurrent chromosomal translocations underlie both haematopoietic and solid tumours. Their origin has been ascribed to selection of random rearrangements, targeted DNA damage, or frequent nuclear ...interactions between translocation partners; however, the relative contribution of each of these elements has not been measured directly or on a large scale. Here we examine the role of nuclear architecture and frequency of DNA damage in the genesis of chromosomal translocations by measuring these parameters simultaneously in cultured mouse B lymphocytes. In the absence of recurrent DNA damage, translocations between Igh or Myc and all other genes are directly related to their contact frequency. Conversely, translocations associated with recurrent site-directed DNA damage are proportional to the rate of DNA break formation, as measured by replication protein A accumulation at the site of damage. Thus, non-targeted rearrangements reflect nuclear organization whereas DNA break formation governs the location and frequency of recurrent translocations, including those driving B-cell malignancies.
Sensitization to protease allergens, such as papain, or helminth infection is associated with basophil recruitment to draining lymph nodes (LNs). Basophils have the capacity to present antigen to ...naive T cells and promote TH2 differentiation directly or indirectly through IL-4 production.
We studied how papain induces basophil migration to LNs and the contribution of various leukocytes to papain-induced immune responses.
We immunized mice in the footpad with papain and studied leukocyte recruitment and inflammatory cytokine and chemokine production in the draining popliteal LNs.
Papain directly activated naive T cells through protease-activated receptor (PAR) 2 to initiate a chemokine/cytokine program that includes CCL17, CCL22, and IL-4. Papain-triggered innate immune responses were dependent on both CD4 T cells and PAR2 and were strongly reduced in the absence of CCR4, the primary receptor for CCL17/CCL22.
These results elucidate a novel innate allergen-recognition pathway mediated by naive T cells through PAR2, which provide an immediate source of chemokines and IL-4 upstream of basophils and antigen-restricted TH2 differentiation. PAR2 antagonism might thus hold promise for the treatment of allergic disease.
Aberrant activity of the phosphatidylinositol 3-kinase (PI3K) pathway supports growth of many tumors including those of breast, lung, and prostate. Resistance of breast cancer cells to targeted ...chemotherapies including tyrosine kinase inhibitors (TKI) has been linked to persistent PI3K activity, which may in part be due to increased membrane expression of epidermal growth factor (EGF) receptors (HER2 and HER3). Recently we found that proteins of the RGS (regulator of G protein signaling) family suppress PI3K activity downstream of the receptor by sequestering its p85α subunit from signaling complexes. Because a substantial percentage of breast tumors have RGS16 mutations and reduced RGS16 protein expression, we investigated the link between regulation of PI3K activity by RGS16 and breast cancer cell growth. RGS16 overexpression in MCF7 breast cancer cells inhibited EGF-induced proliferation and Akt phosphorylation, whereas shRNA-mediated extinction of RGS16 augmented cell growth and resistance to TKI treatment. Exposure to TKI also reduced RGS16 expression in MCF7 and BT474 cell lines. RGS16 bound the amino-terminal SH2 and inter-SH2 domains of p85α and inhibited its interaction with the EGF receptor-associated adapter protein Gab1. These results suggest that the loss of RGS16 in some breast tumors enhances PI3K signaling elicited by growth factors and thereby promotes proliferation and TKI evasion downstream of HER activation.
Endoplasmic reticulum(ER)-associated degradation (ERAD) is an essential process for cell homeostasis and remains not well understood. During ERAD, misfolded proteins are recognized, ubiquitinated on ...ER and subsequently retro-translocated/dislocated from ER to the 26S proteasome in the cytosol for proteolytic elimination. Polycystin-2 (PC2), a member of the transient receptor potential superfamily of cation channels, is a Ca channel mainly located on ER and primary cilium membranes of cells. Mutations in PC2 are associated with autosomal dominant polycystic kidney disease (ADPKD). The cellular and molecular mechanisms underlying the PC2-associated pathogenesis remain unclear. Here we show that PC2 degradation is regulated by the ERAD pathway through the ubiquitin–proteasome system. PC2 interacted with ATPase p97, a well-known ERAD component extracting substrates from ER, and immobilized it in perinuclear regions. PC2 also interacted with Herp, an ubiquitin-like protein implicated in regulation of ERAD. We found that Herp is required for and promotes PC2 degradation. ER stress accelerates the retro-translocation of PC2 for cytosolic degradation, at least in part through increasing the Herp expression. Thus, PC2 is a novel ERAD substrate. Herp also promoted, to varied degrees, the degradation of PC2 truncation mutants, including two pathogenic mutants R872X and E837X, as long as they interact with Herp. In contrast, Herp did not interact with, and has no effect on the degradation of, PC2 mutant missing both the N- and C-termini. The ERAD machinery may thus be important for ADPKD pathogenesis because the regulation of PC2 expression by the ERAD pathway is altered by mutations in PC2.
Many tumors are characterized by recurrent translocations between a tissue-specific gene and a proto-oncogene. The juxtaposition of the Ig heavy chain gene and Myc in Burkitt’s lymphoma and in murine ...plasmacytoma is a classic example. Regulatory elements within the heavy chain constant region locus are required for Myc translocation and/or deregulation. However, many genes are regulated by cis-acting elements at distances up to 1,000 kb outside the locus. Such putative distal elements have not been examined for the heavy chain locus, particularly in the context of Myc translocations. We demonstrate that a transgene containing the Ig heavy chain constant region locus, inserted into five different chromosomal locations, can undergo translocations involving Myc . Furthermore, these translocations are able to generate plasmacytomas in each transgenic line. We conclude that the heavy chain constant region locus itself includes all of the elements necessary for both the translocation and the deregulation of the proto-oncogene.
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