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Longitudinal studies associate shiftwork with cardiometabolic disorders but do not establish causation or elucidate mechanisms of disease. We developed a mouse model based on shiftwork schedules to study circadian misalignment in both sexes. Behavioral and transcriptional rhythmicity were preserved in female mice despite exposure to misalignment. Females were protected from the cardiometabolic impact of circadian misalignment on a high-fat diet seen in males. The liver transcriptome and proteome revealed discordant pathway perturbations between the sexes. Tissue-level changes were accompanied by gut microbiome dysbiosis only in male mice, biasing toward increased potential for diabetogenic branched chain amino acid production. Antibiotic ablation of the gut microbiota diminished the impact of misalignment. In the United Kingdom Biobank, females showed stronger circadian rhythmicity in activity and a lower incidence of metabolic syndrome than males among job-matched shiftworkers. Thus, we show that female mice are more resilient than males to chronic circadian misalignment and that these differences are conserved in humans.

In this Editorial, co-Chief Scientific Advisors of Science Translational Medicine, Elazer Edelman and Garret FitzGerald, discuss challenges and opportunities for the next decade of translational research.

Biomarker tests for molecularly targeted therapies might be the key to unlocking the entry gate to precision medicine.

The absence of Bmal1, a core clock gene, results in a loss of circadian rhythms, an acceleration of aging, and a shortened life span in mice. To address the importance of circadian rhythms in the aging process, we generated conditional Bmal1 knockout mice that lacked the BMAL1 protein during adult life and found that wild-type circadian variations in wheel-running activity, heart rate, and blood pressure were abolished. Ocular abnormalities and brain astrogliosis were conserved irrespective of the timing of Bmal1 deletion. However, life span, fertility, body weight, blood glucose levels, and age-dependent arthropathy, which are altered in standard Bmal1 knockout mice, remained unaltered, whereas atherosclerosis and hair growth improved, in the conditional adult-life Bmal1 knockout mice, despite abolition of clock function. Hepatic RNA-Seq revealed that expression of oscillatory genes was dampened in the adult-life Bmal1 knockout mice, whereas overall gene expression was largely unchanged. Thus, many phenotypes in conventional Bmal1 knockout mice, hitherto attributed to disruption of circadian rhythms, reflect the loss of properties of BMAL1 that are independent of its role in the clock. These findings prompt reevaluation of the systemic consequences of disruption of the molecular clock.

In this case study, an early-career mechanical engineer interviews an established translational bioscientist about mechanisms for merging engineering and biomedicine to pursue clinically informed research questions.

Prostacyclin (PGI(2)) is a vasodilator and platelet inhibitor, properties consistent with cardioprotection. More than a decade ago, inhibition of cyclooxygenase-2 (COX-2) by the nonsteroidal anti-inflammatory drugs (NSAIDs) rofecoxib and celecoxib was found to reduce the amount of the major metabolite of PGI(2) (PGI-M) in the urine of healthy volunteers. This suggested that NSAIDs might cause adverse cardiovascular events by reducing production of cardioprotective PGI(2). This prediction was based on the assumption that the concentration of PGI-M in urine likely reflected vascular production of PGI(2) and that other cardioprotective mediators, especially nitric oxide (NO), were not able to compensate for the loss of PGI(2). Subsequently, eight placebo-controlled clinical trials showed that NSAIDs that block COX-2 increase adverse cardiovascular events. We connect tissue-specific effects of NSAID action and functional correlates in mice with clinical outcomes in humans by showing that deletion of COX-2 in the mouse vasculature reduces excretion of PGI-M in urine and predisposes the animals to both hypertension and thrombosis. Furthermore, vascular disruption of COX-2 depressed expression of endothelial NO synthase and the consequent release and function of NO. Thus, suppression of PGI(2) formation resulting from deletion of vascular COX-2 is sufficient to explain the cardiovascular hazard from NSAIDs, which is likely to be augmented by secondary mechanisms such as suppression of NO production.

Testosterone is necessary for the development of male pattern baldness, known as androgenetic alopecia (AGA); yet, the mechanisms for decreased hair growth in this disorder are unclear. We show that prostaglandin D(2) synthase (PTGDS) is elevated at the mRNA and protein levels in bald scalp compared to haired scalp of men with AGA. The product of PTGDS enzyme activity, prostaglandin D(2) (PGD(2)), is similarly elevated in bald scalp. During normal follicle cycling in mice, Ptgds and PGD(2) levels increase immediately preceding the regression phase, suggesting an inhibitory effect on hair growth. We show that PGD(2) inhibits hair growth in explanted human hair follicles and when applied topically to mice. Hair growth inhibition requires the PGD(2) receptor G protein (heterotrimeric guanine nucleotide)-coupled receptor 44 (GPR44), but not the PGD(2) receptor 1 (PTGDR). Furthermore, we find that a transgenic mouse, K14-Ptgs2, which targets prostaglandin-endoperoxide synthase 2 expression to the skin, demonstrates elevated levels of PGD(2) in the skin and develops alopecia, follicular miniaturization, and sebaceous gland hyperplasia, which are all hallmarks of human AGA. These results define PGD(2) as an inhibitor of hair growth in AGA and suggest the PGD(2)-GPR44 pathway as a potential target for treatment.

Multisectoral collaborative models for drug and therapeutic research and development (R&D) are emerging, requiring a recalibration of how intellectual property rights (IPRs) are used. Although these models appear promising, little study has been conducted on the optimal blend of sharing and exclusion as mediated through the proactive use or nonuse of IPRs. This Commentary is a call for a combination of theoretical and empirical analyses to build a comprehensive understanding of the interplay between formal IP laws, institutions that administer and manage IPRs, and the use of IPRs in practice to better construct and manage collaborations. Such analyses require outcome metrics formulated to measure the success of therapeutic outcomes and to capture the complexity of a highly networked R&D environment.

[Figure][1] Elazer R. Edelman is the Thomas D. and Virginia W. Cabot Professor of Health Sciences and Technology at MIT, Professor of Medicine at Harvard Medical School, a coronary care unit cardiologist at the Brigham and Women's Hospital, and Director of the Harvard-MIT Biomedical

> Sometimes the questions are complicated and the answers are simple. > > —Dr. Seuss, author of The Cat in the Hat It is 5 months since Francis Collins, the director of the U.S. National Institutes of Health (NIH), first announced his proposal to found a new National Center for Advancing

To achieve advances in clinical medicine, we need investigators with a sophisticated understanding of medicine and pharmacology who are capable of projecting their preclinical research across the translational divide. Such expertise in translational medicine and therapeutics has become scant in academia, industry, and regulatory bodies. Here we discuss strategies for addressing this deficit in human capital.

A conversation about the Commentary published in the 7 April 2010 issue of Science Translational Medicine . Length: 12 min File size: 5.7 MB File Format: mp3 Download Podcast: [ http://podcasts.aaas.org/science\_transl\_med/ScienceTranslMed_100407.mp3][1] [Download the Transcript][2] (Adobe PDF format) [1]: http://podcasts.aaas.org/science_transl_med/ScienceTranslMed_100407.mp3 [2]: http://stm.sciencemag.org/content/suppl/2010/04/05/2.26.26pc2.DC1/ScienceTranslMed_100407.pdf