No abstract

The avian skeletal alpha-actin gene was used as a template for construction of a myogenic expression vector that was utilized to direct expression of a human IGF-I cDNA in cultured muscle cells and in striated muscle of transgenic mice. The proximal promoter region, together with the first intron and 1.8 kilobases of 3'-noncoding flanking sequence of the avian skeletal alpha-actin gene directed high level expression of human insulin-like growth factor I (IGF-I) in stably transfected C2C12 myoblasts and transgenic mice. Expression of the actin/IGF-I hybrid gene in C2C12 muscle cells increased levels of myogenic basic helix-loop-helix factor and contractile protein mRNAs and enhanced myotube formation. Expression of the actin/IGF-I hybrid gene in mice elevated IGF-I concentrations in skeletal muscle 47-fold resulting in myofiber hypertrophy. IGF-I concentrations in serum and body weight were not increased by transgene expression, suggesting that the effects of transgene expression were localized. These results indicate that sustained overexpression of IGF-I in skeletal muscle elicits myofiber hypertrophy and provides the basis for manipulation of muscle physiology utilizing skeletal alpha-actin-based vectors.

Previous studies on company scores conducted at firm-level, generally concluded that there exists a positive relation between company scores and stock returns. Motivated by these studies, this study examines the relationship between company scores (Corporate Governance Score, Economic Score, Environmental Score, and Social Score) and stock returns, both at portfolio-level analysis and firm-level cross-sectional regressions. In portfolio-level analysis, stocks are sorted based on each company scores and quintile portfolio are formed with different levels of company scores. Then, existence and significance of raw returns and risk-adjusted returns difference between portfolios with the extreme company scores (portfolio 10 and portfolio 1) is tested. In addition, firm-level cross-sectional regression is performed to examine the significance of company scores effects with control variables. While portfolio-level analysis results indicate that there is no significant relation between company scores and stock returns; firm-level analysis indicates that economic, environmental, and social scores have effect on stock returns, 220 however, significance and direction of these effects change, depending on the included control variables in the cross-sectional regression.

A high-throughput, retrovirus-mediated mutagenesis method based on gene trapping in embryonic stem cells was used to identify a novel mouse gene. The human ortholog encodes a transmembrane protein containing five extracellular immunoglobulin-like domains that is structurally related to human NEPHRIN, a protein associated with congenital nephrotic syndrome. Northern analysis revealed wide expression in humans and mice, with highest expression in kidney. Based on similarity to NEPHRIN and abundant expression in kidney, this protein was designated NEPH1 and embryonic stem cells containing the retroviral insertion in the Neph1 locus were used to generate mutant mice. Analysis of kidney RNA from Neph1 ؊/؊ mice showed that the retroviral insertion disrupted expression of Neph1 transcripts. Neph1 ؊/؊ pups were represented at the expected normal Mendelian ratios at 1 to 3 days of age but at only 10% of the expected frequency at 10 to 12 days after birth, suggesting an early postnatal lethality. The Neph1 ؊/؊ animals that survived beyond the first week of life were sickly and small but without edema, and all died between 3 and 8 weeks of age. Proteinuria ranging from 300 to 2,000 mg/dl was present in all Neph1 ؊/؊ mice. Electron microscopy demonstrated NEPH1 expression in glomerular podocytes and revealed effacement of podocyte foot processes in Neph1 ؊/؊ mice. These findings suggest that NEPH1, like NEPHRIN, may play an important role in maintaining the structure of the filtration barrier that prevents proteins from freely entering the glomerular urinary space.NEPHRIN is a transmembrane protein of the immunoglobulin (Ig) superfamily that is expressed by epithelial podocytes of developing glomeruli (13, 17). Congenital nephrotic syndrome of the Finnish type results from mutations in NPHS1, the human gene encoding NEPHRIN, indicating a role for NEPHRIN in maintaining the filtration barrier that prevents proteins from freely entering the glomerular urinary space (6,17). Recent studies localized NEPHRIN to the slit diaphragms that form the junctions between podocyte foot processes interdigitating along the glomerular basement membrane. This and other studies suggest that NEPHRIN proteins extending toward each other from adjacent podocyte foot processes may interdigitate in a zipper-like structure to form the crucial filtration barrier in the slit diaphragm. The eight Ig-like domains of each NEPHRIN protein, which are of the C2 type of Ig domain known to be involved in cell-cell interactions, are thought to provide the homophilic interactions that bind these NEPHRIN proteins together (13, 17).We use a high-throughput mutagenesis method based on gene trapping in embryonic stem (ES) cells that allows automated production of sequence tags from the trapped and mutated genes (20). These ES cell clones are stored in a library called Omnibank, and the sequence tag from the gene trapped in each clone, referred to as the Omnibank sequence tag or OST, is entered into a searchable database. A protein with Ig domains was identified with...

Akt kinases 1, 2, and 3 are important regulators of cell survival and have been shown to be constitutively active in a variety of human tumors. GSK690693 is a novel ATP-competitive, low-nanomolar pan-Akt kinase inhibitor. It is selective for the Akt isoforms versus the majority of kinases in other families; however, it does inhibit additional members of the AGC kinase family. It causes dose-dependent reductions in the phosphorylation state of multiple proteins downstream of Akt, including GSK3B, PRAS40, and Forkhead. GSK690693 inhibited proliferation and induced apoptosis in a subset of tumor cells with potency consistent with intracellular inhibition of Akt kinase activity. In immune-compromised mice implanted with human BT474 breast carcinoma xenografts, a single i.p. administration of GSK690693 inhibited GSK3B phosphorylation in a dose-and time-dependent manner. After a single dose of GSK690693, >3 Mmol/L drug concentration in BT474 tumor xenografts correlated with a sustained decrease in GSK3B phosphorylation. Consistent with the role of Akt in insulin signaling, treatment with GSK690693 resulted in acute and transient increases in blood glucose level. Daily administration of GSK690693 produced significant antitumor activity in mice bearing established human SKOV-3 ovarian, LNCaP prostate, and BT474 and HCC-1954 breast carcinoma xenografts. Immunohistochemical analysis of tumor xenografts after repeat dosing with GSK690693 showed reductions in phosphorylated Akt substrates in vivo. These results support further evaluation of GSK690693 as an anticancer agent.