Isoginkgetin enhances adiponectin secretion from differentiated adiposarcoma cells via a novel pathway involving AMP-activated protein kinase

Adiponectin is an anti-diabetic hormone secreted by adipocytes. Circulating adiponectin levels are lower in obese and type II diabetic patients than in healthy people. Weight loss or thiazolidinedione treatment increases plasma adiponectin levels. Animal models and human studies suggest that elevated adiponectin levels increase insulin sensitivity. We screened a library of drug-like compounds and natural products for novel agents enhancing adiponectin production. We identified isoginkgetin, a compound derived from the leaves of Ginkgo biloba, to up-regulate adiponectin secretion with potency comparable to that of rosiglitazone, a known modulator of adiponectin production. However, unlike rosiglitazone, peroxisome proliferators-activated receptor gamma activity seems not required for the action of isoginkgetin, and isoginkgetin has only a slight effect on adipogenesis, which makes it an attractive candidate for anti-diabetic treatment. Further investigation revealed that both isoginkgetin and rosiglitazone activate AMP-activated protein kinase (AMPK) in adipocytes. Our findings suggest a novel mechanism for the elevation of adiponectin by isoginkgetin, which is different from that of rosiglitazone. Furthermore, this novel mechanism for adiponectin regulation involving AMPK can potentially facilitate new understanding of metabolic diseases and identification of new targets, as well as agents that increase plasma adiponectin levels.     

HIV-2 and SIV Vector Systems

Lentiviral vectors have received much attention in recent years due to their ability to efficiently transduce non-dividing cells. Of the lentiviruses HIV-2 and SIV offer several unique benefits as the basis for lentiviral vector design. HIV-1, HIV-2 and SIV remain the only known primate lentiviruses, and consequently are among the most extensively studied viruses known. Substantial effort has been devoted towards identifying the pathogenic determinants of the primate lentiviruses and towards understanding their replication within primates. Of the primate lentiviruses, the pathogenicity and rates of transmission of HIV-2 and SIV fall far below that of HIV-1, potentially providing vectors based upon HIV-2/SIV with a greater degree of biosafety. Last, and perhaps most importantly, HIV-2 and SIV are viruses which may be studied within non-human primate models susceptible to AIDS-like disease, making vectors based upon these viruses accessible to substantial preclinical evaluation. We approach this Chapter presenting information regarding the basic biology of HIV-2 and SIV and conclude by pointing to how unique features of HIV-2 and SIV are well suited to vector design, hoping to leave the reader with a greater appreciation of the potential these viruses offer within the field of gene transfer applications.     

HTLV-I infection of T and B cells of a patient with adult T-cell leukemia-lymphoma (ATLL) and transmission of HTLV-I from B cells to normal T cells

We analysed the DNA of different tissues of a patient (HS) with adult T-cell leukemia/lymphoma virus (HTLV-I). We detected viral sequences in fresh specimens from spleen, thymus, liver, skin and peripheral blood neoplastic lymphocytes. The pattern of HTLV-I intergration is identical in the leukemic cells and in all other tissues analysed, but the signal intensity is strongest in the leukemic cells, indicating the source of HTLV-I proviral sequences was the leukemic T-cells which had infiltrated these tissues. In fact, the cultured skin fibroblasts of the patient did not contain HTLV-I sequence. However, cultured lymphocytes of this patient was consistently an immortalized B-cell line containing HTLV-I sequences in a manner indicative of a polyclonal infection. This cell line was also infected with the Epstein-Barr virus (EBV). In order to determine whether HTLV-I alone was sufficient for B-cell immortalization, we obtained single cell clones by limiting dilution. The DNA of all the cell clones that we analysed contained both the HTLV-I and EBV genomes, suggesting that immortalization of the B-cell was more likely due to the EBV rather than HTLV-I. Infectious HTLV-I viruses produced by the B-cell line still had the propensity to infect and transform T-lymphocytes in normal human umbilical cord blood. Unlike the parental B cells, the transformed T lymphocytes were clonally selected. Our results indicate that although the predominant infected cell population of the patient was his leukemic T lymphocytes, some of his EBV-positive B-lymphocytes were also polyclonally infected. The latter had a growth advantage in culture over the T lymphocytes but the virus produced by these immortalized B cells has not been adapted and has maintained its tropism for T cells.     

Transduction of cell lines and primary cells by FIV-packaged HIV vectors.

Human immunodeficiency virus type 1 (HIV-1), simian immunodeficiency virus, and feline immunodeficiency virus (FIV) are capable of packaging viral RNA derived from heterologous as well as homologous lentiviruses, a phenomenon referred to as "cross packaging." To remove the possibility of seroconversion to HIV proteins, and to avoid potential problems arising due to targeting of vector or packaging construct by antiviral genes, we investigated the feasibility of using an FIV-based packaging system to deliver human immunodeficiency virus type 2 (HIV-2)-based vectors bearing anti-HIV-1 RNA expression cassettes to target cells. In the absence of FIV rev, FIV was packaged by HIV-2 at only 3% the efficiency of FIV packaging by FIV, but this was increased to 39% of homologous controls by supplying FIV rev in trans. HIV-2 vectors were packaged by FIV at levels equal to or exceeding the homologous HIV-2 packaging system in the absence of HIV-1 tat and rev, and levels increased approximately four- to fivefold with the addition of tat and rev in trans. HIV-2 vectors bearing a polyribozyme cassette targeting multiple regions of HIV RNA were efficiently packaged by FIV and transferred to target cells. Upon challenge with cell-free HIV-1 (m.o.i. = 0.1) a significant reduction in replication was observed. These findings demonstrate that packaging HIV vectors with FIV is a viable alternative, which avoids use of HIV structural proteins.     

RNA interference and potential applications

RNA interference (RNAi) is the process of using specific sequences of double-stranded RNA (dsRNA) to knock down the expression level of sequence-homologous genes. Such ability of small interfering RNA (siRNA) in mammalian cells will undoubtedly revolutionize the study of functional genomics, the discovery of drug targets and even the treatment of human diseases. In this review we briefly describe the history of RNAi discovery, the RNAi mechanism and the general guideline for siRNA design as well as various methods for siRNA production and delivery. We also introduce the potential applications of siRNA, inducible siRNA and siRNA library in speeding up basic biomedical research and in acting as potential therapeutic agents for treatment of numerous human diseases.     

Familial partial trisomy 6q syndromes resulting from inherited ins (5;6) (q33;q15q27)

Two cases are reported of familial partial trisomy 6q syndrome due to segregation of ins(5;6) (q33;q15q27) in three generations. The common clinical features include growth and mental retardation, feeding difficulty during infancy, microcephaly with downward slanting palpebral fissures, flattened nasal bridge with anteverted and flared nares, long philtrum, high arched palate, partially opened and protruding mouth with receding chin, deep transverse creases of the ears, three creases on the 4th fingers, clinodactyly of the 5th fingers with a single crease, and other dermatoglyphic findings. These characteristic features of two patients appear to make partial trisomy 6q a clinically recognizable syndrome.