Antiretroviral drug therapy (ART) effectively suppresses replication of both the immunodeficiency viruses, human (HIV) and simian (SIV); however, virus rebounds soon after ART is withdrawn. SIV-infected monkeys were treated with a 90-day course of ART initiated at 5 weeks post infection followed at 9 weeks post infection by infusions of a primatized monoclonal antibody against the α4β7 integrin administered every 3 weeks until week 32. These animals subsequently maintained low to undetectable viral loads and normal CD4+ T cell counts in plasma and gastrointestinal tissues for more than 9 months, even after all treatment was withdrawn. This combination therapy allows macaques to effectively control viremia and reconstitute their immune systems without a need for further therapy.

Protein tyrosine phosphatase (PTP) receptor T (PTPRT) is the most frequently mutated PTP in human cancers. However, the cell signaling pathways regulated by PTPRT have not yet been elucidated. Here, we report identification of signal transducer and activator of transcription 3 (STAT3) as a substrate of PTPRT. Phosphorylation of a tyrosine at amino acid Y705 is essential for the function of STAT3, and PTPRT specifically dephosphorylated STAT3 at this position. Accordingly, overexpression of normal PTPRT in colorectal cancer cells reduced the expression of STAT3 target genes. These studies illuminate a mechanism regulating the STAT3 pathway and suggest that this signaling pathway plays an important role in colorectal tumorigenesis.colorectal cancer ͉ tyrosine phosphorylation ͉ signaling T yrosine phosphorylation is coordinately controlled by protein tyrosine kinases and protein tyrosine phosphatases (PTPs) and is a central feature of many signaling pathways involved in tumor development (1). While activating mutations in protein tyrosine kinases have been shown to play vital roles in tumorigenesis, the role of PTPs is less well defined. We recently identified PTP receptor T (PTPRT), also known as PTP , as the most frequently mutated PTP gene in colorectal cancers (CRCs) (2). PTPRT was also mutationally altered in lung and gastric cancers (2). The spectrum of mutations, which included nonsense mutations and frameshift changes, suggested that these alterations were inactivating. Biochemical analyses demonstrated that missense mutations in the catalytic domains of PTPRT diminished its phosphatase activity and overexpression of PTPRT inhibited CRC cell growth (2). Taken together, these studies strongly support the notion that PTPRT normally acts as a tumor suppressor gene. This conclusion was buttressed by a transposon-based somatic mutagenesis screen in mice, wherein PTPRT was isolated as a target gene from two different mouse transgenic sarcomas (3). In light of these data, it is important to understand the mechanisms through which PTPRT is involved in the neoplastic process. Identifying substrates of PTPRT is an important step to elucidating the signal transduction pathways regulated by this phosphatase. Here, we report identification of signal transducer and activator of transcription 3 (STAT3) as a substrate of PTPRT.STAT3 has been shown to play an important role in leukemias, and persistent STAT3 activation has been detected in a variety of hematopoietic malignancies and solid tumors (4-6), including CRCs (7,8). In general, latent cytoplasmic STAT3 becomes activated through phosphorylation of amino acid residue Y705 by cytokine receptor-associated kinase (Jak) or growth factor receptor-associated tyrosine kinase (Src) (6). Phosphorylated STAT3 dimerizes through reciprocal Src homology 2-phosphotyrosine interaction and accumulates in the nucleus (6). STAT3 then activates the transcription of a wide array of genes, including Bcl-XL and SOCS3 (4). In the current study, we demonstrate that PTPRT specifically dephos...

BackgroundMicroRNAs are ~22-nt long regulatory RNAs that serve as critical modulators of post-transcriptional gene regulation. The diversity of miRNAs in endothelial cells (ECs) and the relationship of this diversity to epithelial and hematologic cells is unknown. We investigated the baseline miRNA signature of human ECs cultured from the aorta (HAEC), coronary artery (HCEC), umbilical vein (HUVEC), pulmonary artery (HPAEC), pulmonary microvasculature (HPMVEC), dermal microvasculature (HDMVEC), and brain microvasculature (HBMVEC) to understand the diversity of miRNA expression in ECs.ResultsWe identified 166 expressed miRNAs, of which 3 miRNAs (miR-99b, miR-20b and let-7b) differed significantly between EC types and predicted EC clustering. We confirmed the significance of these miRNAs by RT-PCR analysis and in a second data set by Sylamer analysis. We found wide diversity of miRNAs between endothelial, epithelial and hematologic cells with 99 miRNAs shared across cell types and 31 miRNAs unique to ECs. We show polycistronic miRNA chromosomal clusters have common expression levels within a given cell type.ConclusionsEC miRNA expression levels are generally consistent across EC types. Three microRNAs were variable within the dataset indicating potential regulatory changes that could impact on EC phenotypic differences. MiRNA expression in endothelial, epithelial and hematologic cells differentiate these cell types. This data establishes a valuable resource characterizing the diverse miRNA signature of ECs.

How developmental programs reactivate in regeneration is a fundamental question in biology. We addressed this question through the study of Wound Induced Hair follicle Neogenesis (WIHN), an adult organogenesis model where stem cells regenerate de novo hair follicles following deep wounding. The exact mechanism is uncertain. Here we show that self-noncoding dsRNA activates the anti-viral receptor toll like receptor 3 (TLR3) to induce intrinsic retinoic acid (RA) synthesis in a pattern that predicts new hair follicle formation after wounding in mice. Additionally, in humans, rejuvenation lasers induce gene expression signatures for dsRNA and RA, with measurable increases in intrinsic RA synthesis. These results demonstrate a potent stimulus for RA synthesis by non-coding dsRNA, relevant to their broad functions in development and immunity.

The c-Myc (Myc) oncoprotein is a high-value therapeutic target given that it is deregulated in multiple types of cancer. However, potent small molecule inhibitors of Myc have been difficult to identify, particularly those whose mechanism relies on blocking the association between Myc and its obligate heterodimerization partner, Max. We have recently reported a structure-activity relationship study of one such small molecule, 10074-G5, and generated an analog, JY-3-094, with significantly improved ability to prevent or disrupt the association between recombinant Myc and Max proteins. However, JY-3094 penetrates cells poorly. Here, we show that esterification of a critical para-carboxylic acid function of JY-3-094 by various blocking groups significantly improves cellular uptake although it impairs the ability to disrupt Myc-Max association in vitro. These pro-drugs are highly concentrated within cells where JY-3-094 is then generated by the action of esterases. However, the pro-drugs are also variably susceptible to extracellular esterases, which can deplete extracellular reservoirs. Furthermore, while JY-3-094 is retained by cells for long periods of time, much of it is compartmentalized within the cytoplasm in a form that appears to be less available to interact with Myc. Our results suggest that persistently high extracellular levels of pro-drug, without excessive susceptibility to extracellular esterases, are critical to establishing and maintaining intracellular levels of JY-3-094 that are sufficient to provide for long-term inhibition of Myc-Max association. Analogs of JY-3-094 appear to represent promising small molecule Myc inhibitors that warrant further optimization.