U of M: Pharmacology: Faculty: Burton.

Previously I developed an artificial, intracellular cAMP-elevating transgene, derived from the bacterial gene for cholera toxin (CT). Because cAMP tells a cell to "kick it", the CT transgene can be used to specifically hyperactivate any desired cell or neuron subtype. Thus we can make transgenic mouse models of various diseases for basic research into disease mechanisms and drug testing, and later develop these physiomodulatory and psychomodulatory transgenes for use in human gene therapy.

The CT transgene was used initially to physiologically engineer "Big Mice" -- the first animal model of Gs- and cAMP-dependent pituitary tumorigenesis, in which the growth-hormone producing cells of the pituitary gland become hyperactive and proliferative, causing gigantism, acromegaly and pituitary tumors. More recently, the Burton Lab has combined the CT transgene with different neuron-specific transcriptional promoters as a transgenic pharmacological approach to do actual neuron-resolution "circuit testing" of behavior -- by chronically potentiating (increasingthe responsiveness) of genetically-defined subtypes of neurons in the brain. Mice carrying these neuron-hyperactivating genes have a variety of motor and behavioral disorders, whose analysis is helping to elucidate the precise behavioral role of different neural circuits in the brain, and the role of specific neurons in the etiology or manifestation of human neurological diseases.

Most recently, our University lab has relocated off-campus to a combined academic + commercial biotech incubator, adjacent to our start-up "small pharma" company, Psyncretis Inc. With both basic and spin-off applied research labs, we plan to do "translational" research to both understand the biology of, and design new drugs to treat, various forms of cancer and neurological diseases, as described below:

Project 1. A Transgenic Mouse Model of Comorbid Tourette's Syndrome and Obsessive-Compulsive Disorder (TS+OCD)

Most genetic, organic, or autoimmune neuropsychiatric disorders' socially-devastating symptoms, regardless of their molecular origin, are probably mediated through specific hyperactivated or deactivated neuronal circuits. Yet for most behavioral disorders no more is known about their circuitry, or neuronal basis, than their molecular basis (Eric Kandel, Cell 2000 Millennial Issue). One disorder where it will be as important to precisely understand the responsible neural circuit as the responsible molecular causes is comorbid TS+OCD (Tourette's Syndrome plus Obsessive-Compulsive Disorder):

About 10 million persons in the USA suffer from the tic disorder TS, its frequently (40-80%) comorbid compulsive disorder OCD, or the OCD-related compulsive hair- and skin- biting and pulling disorder trichotillomania (TTM). One of the Burton Lab's projects is to help determine the specific neuronal basis of the tics and compulsions in comorbid TS+OCD and related disorders like TTM, and to pre-clinically test the next generation of therapeutic drugs for tics and compulsions, by modeling these human disorders in mice.

To elucidate the neuron circuits that cause TS+OCD symptoms, we transgenically hyperactivated in mice some of the same cortical-limbic neurons proposed to be hyperactive in human TS and OCD. This created a neuropotentiated transgenic mouse model exhibiting not only TS+OCD-like regional cortical-limbic hyperactivation, but also its ensuing TS+OCD-like symptoms -- including tics that begin at juvenile age in mice, are voluntarily suppressible, and are more prevalent in male mice (as in kids with TS); and comorbid non-stereotypic compulsion-like symptoms, such as OCD-like generalized perseveration of any and all normal behaviors, repetitive leaping and grooming, and TTM-like biting and skin pulling. The mice's TS+OCD-like behaviors are also aggravated by stress, as in TS+OCD, and respond to current therapeutic drugs for TS and OCD.

TS+OCD-like Mice	TS-like tics	TS+OCD-like leaping	OCD/TTM-like biting
OCD-like perseverance	perseverant dig	perseverant bar-hang	perseverant groom

Our knowledge of the precise subset of somatosensory/insular-sensorimotor, orbitofrontal and limbic neurons selectively potentiated in the TS+OCD-like transgenic mice points to a precise "neuronal" model of TS+OCD, which merges the 3 prior dopamine, serotonin and glutamate "neurotransmitter" models and has recently been supported by new clinical glutamate neuroimaging studies of OCD -- the "Cortical-limbic Glutamatergic Neuron" (CGN) model. Based on this model, we have identified new anti-glutamatergic drugs that should be useful for treating human TS, OCD and TTM, and are in the process of bringing them to clinical trial with clinician colleagues at Children's Hospital Medical Center of Cincinnati's TS Clinic.

Cortical-Limbic Glutamatergic Neuron (CGN) Model of TS+OCD Symptoms

Normal Behavior

TS+OCD Symptoms

D2 antagonist Treatment

5-HT2 antagonist Treatment

Investigating this neuroengineered mouse model's neurochemical and drug-response parallels to human TS+OCD will test the CGN Model of TS+OCD, help to elucidate the precise neuronal basis, and potential pathologic origins, of tics and compulsions, and improve pre-clinical screening of future candidate TS and OCD pharmaceuticals -- which we hope willl be more effective and have fewer side effects than those in use today.

Project 2. Genes Involved in cAMP Regulated Tumorigenesis of Endocrine Cells: The Carcinoma Ets Factors as Potential "Oncoppressors"

The second current project in the Burton Lab focuses on the animal modeling and genome expression analysis of cAMP-regulated tumorigenesis of pituitary, breast, prostate and other neuroendocrine or endocrine cells. The lab is now investigating the carcinogenic role of a novel cAMP-regulated and endocrine secretory cell carcinoma-expressed member of the evolutionarily ancient "ets" family of oncogenic and tumor suppressing transcription factors. The lab has named this new gene "EHF" (ets homologous factor).

MILEGGGVMNLNPGNNLLHQPPAWTDSYSTCNVSSGFFGGQWHEIHPQYWTKYQVWEWLQHLLD TNQLDANCIPFQEFDINGEHLCSMSLQEFTRAAGTAGQLLYSNLQHLKWNGQCSSDLFQSTHNVIV KTEQTEPSIMNTWKDENYLYDTNYGSTVDLLDSKTFCRAQISMTTTSHLPVAESPDMKKEQDPPAE CHTKKHNPRGTHLWEFIRDILLNPDKNPGLIKWEDRSEGVFRFLKSEAVAQLWGKKKNNSSMTYE KLSRAMRYYYKREILERVDGRRLVYKFGKNARGWRENEN

Interestingly, almost all other ets factors are specific to blood cells and cause blood-cell cancers such as leukemias or lymphomas. Hence, considerable interest has resulted from the discovery that EHF and two other newly-found similar ets factors comprise a previously unsuspected ets subfamily associated with major solid tumors, or carcinomas, of the breast, prostate, colon and lung (the solid tissues in which EHF is most highly expressed).

Our characterization of the EHF gene in humans shows that it maps to the as-yet-unassigned breast and prostate tumor suppressor locus 11p12-13 (a chromosome region that undergoes deletion or loss-of-heterozygosity in up to 40% of mammary and prostatic tumors); is highly transcribed in normal human breast and prostate; and encodes a bifunctional transcription factor that represses angiogenic matrix metalloproteinase (MMP) gene promoters known for mediating tumors' metastasis to other sites in the body. Even more interesting, EHF's transcription is so far 100% inversely correlated with metastatic potential in all examined breast and prostate cancer cell lines -- meaning that it is not improbable that EHF may prove to be either a marker for, or a suppressor of, tumor malignancy.

Finally, because ets factors evolved to alter gene expression by binding other transcription factor complexes and altering the nature and extent of their activity, EHF may be one of a potential class of bi-functional cancer regulators that "swing both ways". For example, EHF factor can both stimulate and repress the transcription of different cancer-causing MMP genes -- hinting that EHF may represent a still-hypothetical type of regulatory molecule the lab has dubbed a "dichotomous oncoregulator", or "oncoppressor" -- a protein that is both an oncoprotein and a tumor suppressor, depending on the variable cell types or tumor stages in which it is expressed. Given EHF's status as an intracellular milieu-dependent bifunctional transactivator-repressor, we predict that EHF may be a breast and prostate tumor suppressor, but have opposite, oncogenic properties in tissues other than breast or prostate. Transgenic experiments are in progress to overexpress EHF in multiple mouse tissues, which will address the possibility that EHF functions as an "oncoppressor". More generally, we also hope that further analysis of EHF and the genes it regulates will help identify new prognostic biomarkers, new genes and new drug targets associated with aggressive metastatic carcinomas.

The Burton Lab's Past Members

Frank H. Burton, Keith M. Campbell, Li-Yan Sun, Debashis Chowdhury, Michelle A. (Shelli) Bochert, Michael J. (Mike) McGrath, Robert M. (Bob) Rohland, Laurie A. Kleinbaum-Fink, Stephanie D. (Steph) Satoskar, Greg P. Coffey, Matthew B. (Matt) Veldman, Clinton R. (Clint) Parks III, Eric J. Nordstrom, Jenny L. Whittaker, Nathan (Nate) Jorgensen, Jen Boe, Joshua (Josh) G. Jackson, Ji-Young Cha, Daniel J. Kim, A. Ernesto (Ernie) Cuadra, Ted J. Gooden, Kevin Mace, Sarah Baker, Henry Cousineau, Kathy Tuzinski, Dianne Marti, Sue Drake, Catherine (Cathy) Johnson, Katie Bittner.

Pharmacology Faculty

Research Interests

The Burton Lab's Past Members