2006 Off Campus Research Internship Awardee

Marissa Patterson (Biology)


Activities Associated with Award

Mentor: Andrew J. Patterson, M.D., Ph.D. (Stanford University School of Medicine Department of Anesthesia. Division of Critical Care Medicine.)


The Effects of Doxycycline on Cardiac and Non-cardiac
Beta2AR Expression

To gauge the expression of Beta2 adrenergic receptors (Beta2ARs) in the hearts of conditional cardiac specific Beta2AR knockout mice (Beta2KO) after doxycycline administration.

Beta1ARs and Beta2Rs: Previous studies using conventional Beta2KO mice have provided evidence that Beta2AR activation protects the murine heart during continuous Beta1AR stimulation. This finding is significant for clinical medicine because continuous Beta1AR stimulation has been shown to mediate much of the myocardial injury that occurs in congestive heart failure. Why Beta2AR activation is protective during continuous Beta1AR stimulation is unclear, but may be related to the Beta2ARs ability to couple to inhibitory G protein (which Beta1ARs cannot do). Beta1ARs and Beta2ARs are otherwise very similar receptors and are activated by the same ligands.

Conditional versus Conventional Beta2KO Mice: The previous studies demonstrating that Beta2AR activation protects the murine heart during continuous Beta1AR stimulation were performed using conventional Beta2KO mice. These animals develop in utero and postnatally without Beta2ARs, suggesting that the animals may develop means to compensate for the absence of Beta2ARs. In addition, the Beta2AR disruption in these animals is not cardiac specific. Therefore, it was not clear from the previous studies whether cardiac or non-cardiac Beta2ARs conveyed the observed protective effects.

TetR and Cre/loxP Conditional Knockout: I will study mice with a conditional cardiac specific Beta2AR disruption. The animals were engineered such that cardiac specific expression of a reverse transcriptional transactivator results in cre expression and disruption of the Beta2AR gene only in the presence of an inducer, doxycycline. In theory, we should be able to disrupt only cardiac Beta2AR expression at any time in these adult animals by administering doxycycline.

My Project ñ Analysis of the Conditional Cardiac Specific Knockout: I will assess cardiac and non-cardiac Beta2AR expression in the conditional Beta2KO mice after increasing doses of doxycycline. I will use the following approach:

1. I will study four groups of animals (5 animals in each group): Wild Type, Conventional Beta2KO, Untreated Conditional Beta2KO, and Treated Conditional Beta2KO.

2. For treated Conditional Beta2KO mice I will administer doxycycline (from 0.5 mg/day infusion to 6 mg/day infusion) for 5 days using subcutaneous infusion pumps.

3. After sacrificing the animals, I will harvest RNA from their hearts and tails.

4. I will produce cDNA using reverse transcription polymerase chain reaction (rtPCR), then perform conventional PCR using primers designed to amplify a segment of the Beta2AR. I will also perform PCR using primers designed to amplify a segment of the neomycin cassette that was inserted within the floxed segment immediately upstream from the Beta2AR gene in conditional Beta2KO mice.

I will work with another student and a research associate in the host laboratory. With the exception of rtPCR, I learned to perform all of the proposed techniques last summer while working in the host laboratory.


Activities Associated with Award

Meeting/Poster Presentation:

Presented at the The National Institute of Health Conference - "Functional Genomics of Critical Illness and Injury" November 13th and 14th, 2006.

  • Poster Title: "Catecholamine-induced stress and Heart Failure: Can β2 Adrenergic Receptor Activation Protect the Heart and Improve its Function?"
    Marissa Patterson, Brant Walton, Amy Chow, Allen Namath, Jim Wong, Rani
    Agrawal, Andrew J. Patterson.

Presented at Bryn Mawr College Summer Science Internship and Fellowship Poster Session Sept. 7th, 2006.

  • Poster Title: "Generation of a Cardiac Specific Conditional b2 Adrenergic Receptor Knockout Mouse." Marissa Patterson, Ashwin Murthy, Elisa Fung, Tahmina Samad, Rani Agrawal, M.S., Andrew J. Patterson, M.D., Ph.D.


Marissa Patterson, Jim Wong, M.D., Ashwin Murthy, March 2007. Beta-Adrenergic Receptors (βAR): Role in Modulating the Host Immune Response. Seminars in Anesthesia, Perioperative Medicine and Pain.

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