Publications

Comparative genomics has served as an essential guide in the identification of functional coding and non-coding sequences in vertebrate genomes. Human-mouse pair-wise comparisons have limited utility for identifying functional conserved non-coding sequences, owing to the large number of sequences shared between these species. In searching for more stringent filters to uncover non-coding elements more likely to be of functional importance in the human genome, human-fish sequence comparisons have emerged as an important strategy, leading to the efficient identification of enhancer elements. These sequences are unevenly distributed in the genome, tending to cluster around genes involved in key developmental processes, with recent studies suggesting that they represent genomic segments in which sequence variation can result in morphological changes and innovation. These elements, conserved over long evolutionary time, emerge as primary candidates that are likely to harbor sequence variation contributing to susceptibility of human disease phenotypes.

BACKGROUND

The issue of whether regular use of an inhaled beta2-adrenergic agonist worsens airflow and clinical outcomes in asthma is controversial. Retrospective studies have suggested that adverse effects occur in patients with a genetic polymorphism that results in homozygosity for arginine (Arg/Arg), rather than glycine (Gly/Gly), at aminoacid residue 16 of the beta2-adrenergic receptor. However, the existence of any genotype-dependent difference has not been tested in a prospective clinical trial.

METHODS

Patients with mild asthma, not using a controller medication, were enrolled in pairs matched for forced expiratory volume in 1 s (FEV1) according to whether they had the Arg/Arg (n=37; four of 41 matches withdrew before randomisation) or Gly/Gly (n=41) genotype. Regularly scheduled treatment with albuterol or placebo was given in a masked, cross-over design, for 16-week periods. During the study, as-needed albuterol use was discontinued and ipratropium bromide was used as needed. Morning peak expiratory flow rate (PEFR) was the primary outcome variable. The primary comparisons were between treatment period for each genotype; the secondary outcome was a treatment by genotype effect. Analyses were by intention to treat.

FINDINGS

During the run-in period, when albuterol use was kept to a minimum, patients with the Arg/Arg genotype had an increase in morning PEFR of 23 L/min (p=0.0162); the change in patients with the Gly/Gly genotype was not significant (2 L/min; p=0.8399). During randomised treatment, patients with the Gly/Gly genotype had an increase in morning PEFR during treatment with regularly scheduled albuterol compared with placebo (14 L/min [95% CI 3 to 25]; p=0.0175). By contrast, patients with the Arg/Arg genotype had lower morning PEFR during treatment with albuterol than during the placebo period, when albuterol use was limited (-10 L/min [-19 to -2]; p=0.0209). The genotype-attributable treatment difference was therefore -24 L/min (-37 to -12; p=0.0003). There were similar genotype-specific effects in FEV1, symptoms, and use of supplementary reliever medication.

INTERPRETATION

Genotype at the 16th aminoacid residue of the beta2-adrenergic receptor affects the long-term response to albuterol use. Bronchodilator treatments avoiding albuterol may be appropriate for patients with the Arg/Arg genotype.

Lentiviral vectors have undergone several generations of design improvement to enhance their biosafety and expression characteristics, and have been approved for use in human clinical studies. Most preclinical studies with these vectors have employed easily assayed marker genes for the purpose of determining vector titers and transduction efficiencies. Naturally, the adaptation of these vector systems to clinical use will increasingly involve the transfer of genes whose products may not be easily measured, meaning that the determination of vector titer will be more complicated. One method for determining vector titer that can be universally employed on all human immunodeficiency virus type 1-based lentiviral vector supernatants involves the measurement of Gag (p24) protein concentration in vector supernatants by immunoassay. We have studied the effects that manipulation of several variables involved in vector design and production by transient transfection have on vector titer and infectivity. We have determined that manipulation of the amount of transfer vector, packaging, and envelope plasmids used to transfect the packaging cells does not alter vector infectivity, but does influence vector titer. We also found that modifications to the transfer vector construct, such as replacing the internal promoter or transgene, do not generally alter vector infectivity, whereas inclusion of the central polypurine tract in the transfer vector increases vector infectivity on HEK293 cells and human umbilical cord blood CD34+ hematopoietic progenitor cells (HPCs). The infectivities of vector supernatants can also be increased by harvesting at early time points after the initiation of vector production, collection in serum-free medium, and concentration by ultracentrifugation. For the transduction of CD34+ HPCs, we found that the simplest method of increasing vector infectivity is to pseudotype vector particles with the RD114 envelope instead of vesicular stomatitis virus G glycoprotein (VSV-G).

The complete cDNA sequence of the tilapia extracellular Ca(2+)-sensing receptor (CaR) was determined. The transcript length of tilapia CaR (tCaR) is 3.4 kbp and encodes a 940-amino acid, 7-transmembrane domain protein that is consistent in its structural features with known mammalian and piscine CaRs. The tCaR extracellular domain includes a characteristic hydrophobic segment, conserved cysteine residues that are implicated in receptor dimerization (Cys(129) and Cys(131)) and in coupling to the transmembrane domain (nine conserved cysteine residues), and conserved serine residues (Ser(147) and Ser(169-171)) that are linked to receptor binding of Ca(2+) and L-amino acid-mediated potentiation of function. mRNA expression of tCaR was strong in kidney, brain, and gill. Weaker expression was observed in pituitary, stomach, intestine, urinary bladder, and heart. This distribution is consistent with possible physiological roles in endocrine cells, excitable tissues, and ion-transporting barrier epithelia. Expression of tCaR mRNA in kidney and intestine was salinity-dependent, suggesting a role for the receptor in iono-/osmoregulation in this euryhaline teleost species. Human embryonic kidney-293 cells transiently transfected with tCaR cDNA demonstrated dose-dependent phospholipase C activation in response to elevations in the extracellular Ca(2+) concentration ([Ca(2+)](o)). Functional activation of the mitogen-activated protein kinase cascade by high [Ca(2+)](o) was also confirmed in these cells despite the naturally occurring truncation of the receptor's intracellular tail, which removes segments variably linked in mammalian CaRs to filamin-coupled activation of mitogen-activated protein kinase cascades. Sensitivity of phospholipase C activation to [Ca(2+)](o) was dependent on the ionic strength of the bathing medium, supporting a role in salinity sensing.

The epidermal growth factor receptor (EGFR) and its ligands function in diverse cellular functions including cell proliferation, differentiation, motility, and survival. EGFR signaling is important for the development of many tissues, including skin, lungs, intestines, and the craniofacial skeleton. We have now determined the role of EGFR signaling in endochondral ossification. We analyzed long bone development in EGFR-deficient mice. EGFR deficiency caused delayed primary ossification of the cartilage anlage and delayed osteoclast and osteoblast recruitment. Ossification of the growth plates was also abnormal resulting in an expanded area of growth plate hypertrophic cartilage and few bony trabeculae. The delayed osteoclast recruitment was not because of inadequate expression of matrix metalloproteinases, including matrix metalloproteinase-9, which have previously been shown to be important for osteoclast recruitment. EGFR was expressed by osteoclasts, suggesting that EGFR ligands may act directly to affect the formation and/or function of these cells. EGFR signaling regulated osteoclast formation. Inhibition of EGFR tyrosine kinase activity decreased the generation of osteoclasts from cultured bone marrow cells.

BACKGROUND

Phosphorylation of sphingosine by sphingosine kinase (SK) is the rate-limiting step in the cellular synthesis of sphingosine 1-phosphate (S1P). The monoganglioside GM1, which stimulates SK, is cardioprotective in part through increased generation of S1P that protects myocytes by diverse mechanisms. Because protein kinase C (PKC)epsilon activation is necessary for myocardial ischemic preconditioning (IPC) and PKC activators increase SK activity, we tested the hypothesis that SK may be a central mediator of IPC.

METHODS AND RESULTS

In adult murine hearts, IPC sufficient to reduce infarct size significantly increased cardiac SK activity, induced translocation of SK protein from the cytosol to membranes, and enhanced cardiac myocyte survival. IPC did not increase SK activity in PKCepsilon-null mice. The SK antagonist N,N-dimethylsphingosine inhibited PKCepsilon activation and directly abolished the protective effects of IPC and the enhanced SK activity induced by IPC.

CONCLUSIONS

These findings demonstrate that PKCepsilon is thus recruited by IPC and induces activation of SK that then mediates IPC-induced cardioprotection in murine heart.