Murine chronic graft-versus-host disease proteome profiling discovers CCL15 as a novel biomarker in patients.

Improved diagnostic and treatment methods are needed for chronic graft-versus-host disease (cGVHD), the leading cause of late nonrelapse mortality (NRM) in long-term survivors of allogenic hematopoietic cell transplantation. Validated biomarkers that facilitate disease diagnosis and classification generally are lacking in cGVHD. Here, we conducted whole serum proteomics analysis of a well-established murine multiorgan system cGVHD model. We discovered 4 upregulated proteins during cGVHD that are targetable by genetic ablation or blocking antibodies, including the RAS and JUN kinase activator, CRKL, and CXCL7, CCL8, and CCL9 chemokines. Donor T cells lacking CRK/CRKL prevented the generation of cGVHD, germinal center reactions, and macrophage infiltration seen with wild-type T cells. Whereas antibody blockade of CCL8 or CXCL7 was ineffective in treating cGVHD, CCL9 blockade reversed cGVHD clinical manifestations, histopathological changes, and immunopathological hallmarks. Mechanistically, elevated CCL9 expression was present predominantly in vascular smooth muscle cells and uniquely seen in cGVHD mice. Plasma concentrations of CCL15, the human homolog of mouse CCL9, were elevated in a previously published cohort of 211 cGVHD patients compared with controls and associated with NRM. In a cohort of 792 patients, CCL15 measured at day +100 could not predict cGVHD occurring within the next 3 months with clinically relevant sensitivity/specificity. Our findings demonstrate for the first time the utility of preclinical proteomics screening to identify potential new targets for cGVHD and specifically CCL15 as a diagnosis marker for cGVHD. These data warrant prospective biomarker validation studies.

CRISPR/Cas9-Based Cellular Engineering for Targeted Gene Overexpression.

Gene and cellular therapies hold tremendous promise as agents for treating genetic disorders. However, the effective delivery of genes, particularly large ones, and expression at therapeutic levels can be challenging in cells of clinical relevance. To address this engineering hurdle, we sought to employ the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 system to insert powerful regulatory elements upstream of an endogenous gene. We achieved robust activation of the COL7A1 gene in primary human umbilical cord blood CD34⁺ hematopoietic stem cells and peripheral blood T-cells. CD34⁺ cells retained their colony forming potential and, in a second engineering step, we disrupted the T-cell receptor complex in T-cells. These cellular populations are of high translational impact due to their engraftment potential, broad circulatory properties, and favorable immune profile that supports delivery to multiple recipients. This study demonstrates the feasibility of targeted knock in of a ubiquitous chromatin opening element, promoter, and marker gene that doubles as a suicide gene for precision gene activation. This system merges the specificity of gene editing with the high level, sustained gene expression achieved with gene therapy vectors. We predict that this design concept will be highly transferrable to most genes in multiple model systems representing a facile cellular engineering platform for promoting gene expression.

Rapid generation of Col7a1-/- mouse model of recessive dystrophic epidermolysis bullosa and partial rescue via immunosuppressive dermal mesenchymal stem cells.

Recessive dystrophic epidermolysis bullosa (RDEB) is a debilitating and ultimately lethal blistering disease caused by mutations to the Col7a1 gene. Development of novel cell therapies for the treatment of RDEB would be fostered by having immunodeficient mouse models able to accept human cell grafts; however, immunodeficient models of many genodermatoses such as RDEB are lacking. To overcome this limitation, we combined the clustered regularly interspaced short palindromic repeats and associated nuclease (CRISPR/Cas9) system with microinjection into NOD/SCID IL2rγcnull (NSG) embryos to rapidly develop an immunodeficient Col7a1-/- mouse model of RDEB. Through dose optimization, we achieve F0 biallelic knockout efficiencies exceeding 80%, allowing us to quickly generate large numbers of RDEB NSG mice for experimental use. Using this strategy, we clearly demonstrate important strain-specific differences in RDEB pathology that could underlie discordant results observed between independent studies and establish the utility of this system in proof-of-concept human cellular transplantation experiments. Importantly, we uncover the ability of a recently identified skin resident immunomodulatory dermal mesenchymal stem cell marked by ABCB5 to reduce RDEB pathology and markedly extend the lifespan of RDEB NSG mice via reduced skin infiltration of inflammatory myeloid derivatives.

Osteoclasts direct bystander killing of bone cancer.

Primary and metastatic bone cancers are difficult to eradicate and novel approaches are needed to improve treatment and extend life. As bone cancer grows, osteoclasts, the principal bone-resorbing cells of the body, are recruited to and activated at sites of cancer. In this investigation, we determined if osteoclast lineage cells could function as a cell-based gene delivery system to bone cancers. We used the cytosine deaminase (CD) 5-fluorocytosine (5-FC) enzyme/prodrug system and studied bone marrow and bones from transgenic mice expressing a novel CD gene regulated by the osteoclast tartrate-resistant acid phosphatase (TRAP) gene promoter (Tg/NCD). DsRed2-labeled 2472 sarcoma cells were placed in Tg/NCD osteoclastogenic cultures and treated with 5-FC. 5-FC treatment resulted in profound bystander killing (90%; P < 0.05). The effect of 5-FC treatment on osteoclast lineage cells was most dramatic when administered at the beginning of the 7-day cultures, suggesting that mature osteoclasts are less sensitive to 5-FC. Evaluation of osteoclast-directed bystander killing in vivo revealed dramatic killing of bone cancer with only a modest effect on osteoclast number. Specifically, 5-FC treatment of tumor-bearing Tg/NCD mice or Tg/NCD bone marrow transplanted C3H mice (Tg/NCD-C3H) resulted in 92% and 44% reductions in tumor area, respectively (P < 0.05). Eight of ten 5-FC-treated Tg/NCD mice had complete bone tumor killing and five of six 5-FC-treated Tg/NCD-C3H mice had reduced tumor compared with controls. In addition, Tg/NCD osteoclasts were resistant to 5-FC treatment in vivo, a very important feature, as it identifies osteoclasts as an ideal CD gene delivery system.

miR-29 Regulates Type VII Collagen in Recessive Dystrophic Epidermolysis Bullosa.

Recessive dystrophic epidermolysis bullosa (RDEB) is a complex inherited skin disorder caused by loss-of-function mutations in the COL7A1 gene. For an effective treatment of this disorder to be realized, both a thorough understanding of the regulation of COL7A1 and an understanding of the underlying nature of the complications of RDEB are needed. Currently, both posttranscriptional regulation of COL7A1 and the underlying causes of fibrosis in RDEB patients are poorly understood. Here, we describe a mechanism of regulation, to our knowledge previously unknown, by which micro RNA-29 (miR-29) regulates COL7A1 in a complex network: both directly through targeting its 3' untranslated region at two distinct seed regions and indirectly through targeting an essential transcription factor required for basal COL7A1 expression, SP1. In turn, miR-29 itself is regulated by SP1 activity and transforming growth factor-ß signaling. RDEB mice express high levels of transforming growth factor-ß and significantly lower miR-29 compared with wild-type cohorts. The sustained decrease in miR-29 in RDEB skin leads to an increase of miR-29 target genes expressed in the skin, including profibrotic extracellular matrix collagens. Collectively, we identify miR-29 as an important factor in both regulating COL7A1 and inhibiting transforming growth factor-ß-mediated fibrosis.

Phospholipase C-gamma contains introns shared by src homology 2 domains in many unrelated proteins.

Many proteins with novel functions were created by exon shuffling around the time of the metazoan radiation. Phospholipase C-gamma (PLC-gamma) is typical of proteins that appeared at this time, containing several different modules that probably originated elsewhere. To gain insight into both PLC-gamma evolution and structure-function relationships within the Drosophila PLC-gamma encoded by small wing (sl), we cloned and sequenced the PLC-gamma homologs from Drosophila pseudoobscura and D. virilis and compared their gene structure and predicted amino acid sequences with PLC-gamma homologs in other animals. PLC-gamma has been well conserved throughout, although structural differences suggest that the role of tyrosine phosphorylation in enzyme activation differs between vertebrates and invertebrates. Comparison of intron positions demonstrates that extensive intron loss has occurred during invertebrate evolution and also reveals the presence of conserved introns in both the N- and C-terminal PLC-gamma SH2 domains that are present in SH2 domains in many other genes. These and other conserved SH2 introns suggest that the SH2 domains in PLC-gamma are derived from an ancestral domain that was shuffled not only into PLC-gamma, but also into many other unrelated genes during animal evolution.

Radiation treatment decreases bone cancer pain through direct effect on tumor cells.

The most used treatment for bone cancer pain is radiation; however, the mechanism responsible for analgesia after irradiation is unknown. The mechanistic influence of a single, localized 10-, 20- or 30-Gy dose of radiation on painful behaviors, osteolysis, histopathology and osteoclast number was evaluated in mice with painful femoral sarcomas. Dramatic reductions in pain behaviors (P < 0.05) and osteolysis (P < 0.0001) were seen in mice irradiated with 20 and 30 Gy. Irradiation reduced the tumor area by more than 75% (P < 0.05) but did not affect osteoclast frequency per mm2 tumor. Treatment with 20 Gy prior to tumor injection had no effect on tumor growth or pain behaviors, suggesting that radiation reduces osteolysis and pain through direct tumor effects. To demonstrate that tumor elimination was responsible for reduction in osteolysis and pain, sarcoma cells containing the suicide gene cytosine deaminase (CD) were inoculated into femora. After onset of bone cancer pain, mice were treated with the prodrug 5-fluorocytosine (5-FC). 5-FC treatment significantly reduced both osteolysis (P < 0.0005) and bone cancer pain (P < 0.05). The findings in this study demonstrate that one mechanism through which radiation decreases bone cancer pain is by direct effects on tumor cells.

Lentivirus transduction of human osteoclast precursor cells and differentiation into functional osteoclasts.

Gene transfer into stem cells has been an ongoing priority as a treatment for genetic disease and cancer for more than two decades. Methods described herein, form the basis for providing the cell source to determine if osteoclast precursor cells (OcP) can be used as therapeutic gene delivery systems in vivo. Osteoclasts and tumor associated macrophages or OcP, support survival, tumor progression and osteolysis in bone cancers. Two sources of precursor cells are compared: CD14+ cells, the standard OcP, found abundantly in peripheral blood and CD34+ cells, hematopoietic stem cells that are rare, but which can be expanded into OcP. Our findings characterize cell yield at each step of the transduction process and thus provide essential data for planning future in vivo experiments. In addition we demonstrate that essential functions of OcP are preserved following lentiviral transduction. Specifically, neither the transduction method nor the lentiviral transduction influence the OcP's ability to form osteoclasts, express the marker gene, EGFP, or resorb bone. Finally, we conclude that CD34+ cells yield significantly more transduced cells and form functionally superior osteoclasts in vitro. This study represents a step towards considering human gene therapy for bone cancer by demonstrating successful transduction of human OcP for use as cellular delivery vehicles to sites of bone cancer.

Zinc transport activity of Fear of Intimacy is essential for proper gonad morphogenesis and DE-cadherin expression.

Embryonic gonad formation involves intimate contact between germ cells and specialized somatic cells along with the complex morphogenetic movements necessary to create proper gonad architecture. Previously, we have shown that gonad formation in Drosophila requires the homophilic cell-adhesion molecule Drosophila E-cadherin (DE-cadherin), and also Fear of Intimacy (FOI), which is required for stable accumulation of DE-cadherin protein in the gonad. Here, we present an in vivo structure-function analysis of FOI that strongly indicates that zinc transport activity of FOI is essential for gonad development. Mutant forms of FOI that are defective for zinc transport also fail to rescue morphogenesis and DE-cadherin expression in the gonad. We further show that expression of DE-cadherin in the gonad is regulated post-transcriptionally and that foi affects this post-transcriptional control. Expression of DE-cadherin from a ubiquitous (tubulin) promoter still results in gonad-specific accumulation of DE-cadherin, which is strongly reduced in foi mutants. This work indicates that zinc is a crucial regulator of developmental processes and can affect DE-cadherin expression on multiple levels.

Drosophila fear of intimacy encodes a Zrt/IRT-like protein (ZIP) family zinc transporter functionally related to mammalian ZIP proteins.

Zinc is essential for many cellular processes, and its concentration in the cell must be tightly controlled. The Zrt/IRT-like protein (ZIP) family of zinc transporters have recently been identified as the main regulators of zinc influx into the cytoplasm; however, little is known about their in vivo roles. Previously, we have shown that fear of intimacy (foi) encodes a putative member of the ZIP family that is essential for development in Drosophila. Here we demonstrate that FOI can act as an ion transporter in both yeast and mammalian cell assays and is specific for zinc. We also provide insight into the mechanism of action of the ZIP family through membrane topology and structure-function analyses of FOI. Our work demonstrates that Drosophila FOI is closely related to mammalian ZIP proteins at the functional level and that Drosophila represents an ideal system for understanding the in vivo roles of this family. In addition, this work indicates that the control of zinc by ZIP transporters may play a critical role in regulating developmental processes.

Analysis of distinct tartrate-resistant acid phosphatase promoter regions in transgenic mice.

The tartrate-resistant acid phosphatase (TRAP) is present in multiple tissues, including kidney, liver, lung, spleen, and bone. Recent study of (TRAP) gene expression has provided evidence for distinct promoters within the (TRAP) gene, suggesting that the gene has alternative, tissue-preferred mRNA transcripts. Examination of endogenous (TRAP) exon 1B and 1C mRNA transcripts revealed tissue-preferred transcript abundance with increased exon 1B transcripts detected in liver and kidney and increased exon 1C transcripts detected in bone and spleen. In this investigation, we have made transgenic mice that express a marker gene driven by two candidate promoters, designated BC and C, within the (TRAP) gene. The BC and C promoters are 2.2 and 1.6 kb, respectively, measured from the translation initiation site. Evaluation of BC transgenic lines demonstrated robust expression in multiple tissues. In contrast, significant transgene expression was not detected in C transgenic lines. Evaluation of transgene mRNAs in BC transgenic lines revealed that virtually all expression was in the form of B transcripts, suggesting that the tissue-preferred pattern of endogenous (TRAP) was not replicated in the BC transgenic line. Likewise, osteoclastogenic cultures from BC, but not C, transgenic bone marrow cells expressed the transgene following receptor activator of NFkappaB ligand/macrophage colony-stimulating factor stimulation. In conclusion, when compared with the 2.2-kb BC portion of the (TRAP) promoter region, the 1.6-kb C portion does not account for significant gene expression in vivo or in vitro; production of the bone- and spleen-preferred (TRAP) C transcript must depend on regulatory elements outside of the 2.2-kb promoter. As the majority of currently investigated transcription factors that influence transcriptional regulation of osteoclast gene expression bind within the 1.6-kb C portion of the (TRAP) promoter, it is likely that transcription binding sites outside of the 2.2-kb region will have profound effects on regulation of the gene in vivo and in vitro.

fear of intimacy encodes a novel transmembrane protein required for gonad morphogenesis in Drosophila.

Gonad formation requires specific interactions between germ cells and specialized somatic cells, along with the elaborate morphogenetic movements of these cells to create an ovary or testis. We have identified mutations in the fear of intimacy (foi) gene that cause defects in the formation of the embryonic gonad in Drosophila. foi is of particular interest because it affects gonad formation without affecting gonad cell identity, and is therefore specifically required for the morphogenesis of this organ. foi is also required for tracheal branch fusion during tracheal development. E-cadherin/shotgun is similarly required for both gonad coalescence and tracheal branch fusion, suggesting that E-cadherin and FOI cooperate to mediate these processes. foi encodes a member of a novel family of transmembrane proteins that includes the closely related human protein LIV1. Our findings that FOI is a cell-surface protein required in the mesoderm for gonad morphogenesis shed light on the function of this new family of proteins and on the molecular mechanisms of organogenesis.