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Disease Models & Mechanisms 1, 23-25 (2008) doi:10.1242/dmm.000844

In a 2002 lecture to the AmericanPhysiological Society (APS) RespirationSection, former APS president NormanStaub, Sr. presents, as his first slide, twoimages. The first image is labeled‘Molecular Biology’ and features a gleamingsilver bullet train speeding into the distance.The second is labeled ‘Clinical Medicine’,and depicts a rickety wooden caboosestanding alone. Staub uses this simplifiedmetaphor and visual aid to comment on thestate of the union – or, perhaps more accu-rately, disunion – between clinical medicineand molecular biology (Staub, 2002). Giventhe exponential increase in molecularbiology advances, Staub posits the question,“Why has the potential for applications ofmolecular biology in clinical medicine notbeen realized?” He points to whole animalphysiology as the discipline that connectsclinical medicine with molecular biology.He suggests that basic science’s inefficienttranslation to the clinic, results from itslimited ability to shift its findings from a re-stricted and controlled experimental envi-ronment to the complexity of a completeorganism.

The decline of whole animal physiologyfrom its heyday in the mid 20th century is atrend that has been noted by many re-searchers. The neglect of systems biologyand whole animal physiology has beenlinked to a wide variety of dead ends in sci-entific research. These include missing clin-ically important phenotypes in transgenicor knockout mouse models, which may besubtle or difficult to detect for the averagebiomedical researcher untrained in animalphysiology, as well as wasted effort andexpense incurred during novel drug devel-opment. Of the millions of dollars spent de-veloping potentially effective drug thera-pies, a large expense comes from the waste

incurred when novel compounds that passtests in laboratory animal models fail inclinical trials, perhaps due to a limited un-derstanding of the physiological relation-ship between model organisms and humanpatients.

Several initiatives are addressing this gapin the research process. David Wasserman,Professor of Molecular Physiology andBiophysics at Vanderbilt University, is in-volved with bringing an understanding ofwhole animal physiology back to the fore-front of research. Wasserman serves as di-rector of the Mouse Metabolic PhenotypingCenter (MMPC) at Vanderbilt, one of sevenMMPC facilities in the country funded bythe National Institutes of Health (NIH).These MMPC centers were established bythe National Institute of Diabetes andDigestive and Kidney Diseases (NIDDK) in2001, to provide researchers with an ex-

panded array of information about theirmouse models by using standardizedtesting and diagnostic methods to expeditecharacterization of mouse metabolic phe-notypes.

The rat has been the traditional modelorganism for studies of physiology;however, the genetic tractability of themouse and subsequent availability ofreagents make mice tremendously popularfor research (Fig. 1). As genetic and mole-cular manipulation techniques in themouse continue to expand, the limitationsin the physiologic tests that are necessary toidentify mouse phenotypes have becomemore evident. “The focus of physiology de-partments over the last few decades has notbeen on physiology; it has been on cellbiology, gene transcription and such similartopics,” Wasserman commented. Thus,Wasserman and colleagues are shifting the

Putting molecular disease research intophysiological contextResearchers seek novel ways to promote whole animal physiology and link molecular studies ofdisease with systems biology. Nicole Garbarini investigates.

Nicole Garbarini is at the Vanderbilt University,Nashville, TN, USA

Disease Models & Mechanisms

Fig. 1. The genetic tractability of the mouse makes it popular for research. Courtesy of Andrew Salingerand Monica Justice.

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focus to physiology by applying their animalphysiology expertise to the mouse. Theyhave scaled down tests designed for largerorganisms, making them appropriate forthis smaller animal model. Their effortshave resulted in quality measurements offactors related to diabetes and diabeticcomplications. Researchers can send theirown mice to the MMPC core for testing,which is advantageous since many meta-bolic tests are both difficult and expensiveto set up in a laboratory from scratch.Wasserman and his colleagues are alsoworking to establish a database for mousemodels of diabetes. Additionally, theyengage in outreach efforts by teaching ayearly course on insulin clamp techniquesin mice, so that interested researchers canestablish this popular test in their own lab-oratories.

Beyond metabolic phenotype data, addi-tional information is available to scientistsas the result of large-scale mouse pheno-typing centers and phenotype databases.The Mouse Phenome Database hosted atJackson Laboratories (http://www.jax.org/phenome) provides protocols and in-formation on normals for different mousestrains, as well as an extensive bank of phe-notypic information compiled from multi-ple sources. A large-scale mouse programdeveloped in the RIKEN institute researchcenters in Japan hopes to standardize phe-notypic analysis of mice following N-ethyl-N-nitrosourea (ENU) mutagenesis (http://www.brc.riken.jp/ lab/ jmc/en/).

Perhaps the most advanced effort in pro-viding a standardized phenotyping resourceto a large community is the EuropeanMouse Disease Clinic (EUMODIC).EUMODIC is a European Commission-funded consortium of 18 research centersin eight countries, which will undertake acoordinated effort to phenotype 650mutant mouse lines. The battery of testsbeing performed by the EUMODIC re-searchers was generated from an earlierproject, which ran from 2002 to 2006,known as the European Union MouseResearch for Public Health and IndustrialApplications, or EUMORPHIA. This four-year project resulted in the development ofstandardized protocols to comprehensivelystudy mouse phenotypes, and the protocolswere published in a web repository knownas EMPReSS (European MousePhenotyping Resource for StandardisedScreens, http://empress.har.mrc.ac.uk/).

This project also established a ‘phenome’database dubbed Europhenome (http://www.europhenome.org/).

The development of standard operatingprocedures for mouse phenotyping is alsobeing taken advantage of by investigators,who are seeking to generate genetically ma-nipulated mice at their home institutions.Monica Justice, at Baylor College ofMedicine, is helping to set up a phenotyp-ing core at Baylor, patterned largely after theprotocols and initiatives of the EUMODICSgroup. The core will feature a range of testsincluding analyses of bone density and dys-morphology; clinical chemistry and bloodwork; slit lamp and ophthalmoscope examsof the eyes; and tests of physical attributes,behavior, strength, and locomotion. Justicenotes that the idea of standardization is pro-moted very strongly by the EuropeanMouse Disease Clinic, in that researchersmust demonstrate that their tests of controlstrains meet the norms established by theconsortium. Such a requirement addsquality control to laboratory assays. Justicedescribes how, because human laboratorytests include checks for quality control, thisis needed in animal research, and how it isnow beginning to be implemented.

Training courses for scientists are yetanother way to reintroduce whole animalphysiology and systems biology to cell andmolecular biologists. As an example, anNIH-sponsored course entitled ‘Modelsand Technologies for Defining Phenotype’was hosted at Wake Forest University in2006; the goal of the course was to train re-searchers in defining phenotypes and in thetests relevant to transitioning their basicscientific findings into translational re-search (Penn et al., 2007). Such coursesserve as training modules, and bring phys-iologists and molecular biologists togetherto facilitate communication and collabora-tion. Indeed, collaborative efforts betweenmolecular biology and physiology re-searchers can contribute greatly to increas-ing our overall understanding of wholeanimal physiology and systems biology.

Collaborative efforts between scientificresearchers and veterinary pathologists isanother avenue that is being examined for itspotential to enable a more comprehensiveunderstanding of animal physiology. ANational Academies report published in2005 carefully documented the need for in-creased participation by veterinary doctorsin biomedical research (Committee on the

National Needs for Research in VeterinaryScience & NRC, 2005). The report empha-sizes the training of Doctors of VeterinaryMedicine (DVMs) for work in biomedical re-search, and highlights the usefulness of in-creased collaborations between veterinarypathologists and scientific researchers to in-crease the understanding of, and care for,animal models of disease and of animalsused as test subjects in the laboratory.Michael Lairmore, Chair of the Departmentof Veterinary Biosciences at Ohio StateUniversity, commented that veterinariantraining on its own makes DVMs prime can-didates for understanding differences andabnormalities in the anatomy and physiolo-gy of animal models of disease. Expert un-derstanding of animal physiology is valuablefor recognizing changes that occur in animalmodels of disease, as well as in evaluating theresponse of models used for drug discovery.He notes, however, that additional trainingbeyond the standard comparative physiolo-gy curriculum is needed at the post-DVMlevel. “They [veterinarians] then becomemore focused in an area, such as pathology,and can go much greater in depth,” Lairmorecommented. Many universities and researchcenters are now recognizing the value ofhiring their own highly trained DVMs towork alongside their scientists to better un-derstand genetic and disease models.

Recognition of the importance of wholeanimal physiology is now leading scientiststo re-examine biological indicators using thenew tools generated by advances in genetics,and cell and molecular biology. Oneexample of this is the study of biomarkers,which are objectively quantifiable factorsthat signify the presence of a pathologicalprocess without relying on symptom infor-mation or a pharmacologic response totherapy. Biomarkers can include a variety offactors, such as certain gene transcripts,protein measurements, or metabolic inter-mediates. Robert McBurney, Senior VicePresident of Research and Development,and Chief Scientific Officer at BG Medicine,studies biomarkers and develops bioinfor-matics tools in order to aid efficacious drugdiscovery and development. “In drug dis-covery, animals don’t usually exhibit thesame sort of symptoms [as humans] butthey may have the same molecular under-pinnings in a disease model.” McBurneycommented, “We want to return to a moreholistic or systems-based analysis, but theonly way that we can really do that is if we

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focus not on symptoms, but molecular in-formation.” Thus, McBurney and colleaguesare collaborating with the FDA and severalpharmaceutical companies to discover, anddevelop the use of, biomarkers for liver tox-icity in order to screen for drugs that passpre-clinical tests in the laboratory, but fail inthe clinic due to liver toxicity issues. Suchbiomarker studies could enable scientists tounite their newfound knowledge of molec-ular biology, biochemistry and genetics andexplain the implications of this knowledgein animals or humans at the systems biologylevel. McBurney notes, “This is a return towhole animal physiology and pharmacolo-gy, but with much more granular, molecularmeasurements… We are moving fromsymptom-based diseases to molecular-based diseases.”

What makes a return to investigations ofwhole animal physiology particularly idealnow?Robert McBurney’s view is that this unionof molecular biology and systems biology islargely driven by advances in technologyand information, such as computing powerand sequencing of the human genome.Additionally, he suggests that rising health-care costs are yet another reason whydisease investigation and drug discoveryneed to be optimized. He agrees that in-creased understanding of biology and phys-iology on the level of the whole organismwill help this to become a reality.

Likewise, Monica Justice agrees that therenewed interest in whole animal physiol-ogy is due to our current position in thetimeline of progress, and is built on the ad-

vances of the last few decades. “Now is thetime that we’ve developed the technologiesto look at whole animal physiology,” Justiceremarked, “We have all this molecular in-formation at our fingertips and people arefinding out that you can’t study somethingin isolation. It happens in the context of thewhole complex organism.”

REFERENCESPenn, R. B., Ortega, V. E. and Bleecker, E. R. (2007).

A roadmap to functional genomics. Physiol.Genomics 30, 82-88.

Staub, N. C., Sr (2002). EB2002 Comroe lecture. Wholeanimal physiology redux. Am. J. Physiol. Lung Cell Mol.Physiol. 283, L683-L687.

Committee on the National Needs for Research inVeterinary Science & National Research Council.(2005). Critical needs for research in veterinaryscience. Washington DC: National Academies Press.

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