Joseph Larkin III

Assistant Professor

Department of Microbiology and Cell Science 
Ph.D. (2000) University of Florida,Department of Microbiology and Cell Science
Postdoctoral: The Wistar Institure/The University of Pennsylvania, Philadelphia, PA

Teaching Interest

PCB 5235 Immunology

Description of Research

Research Experience

The Wistar Institute & The University of Pennsylvania:The Significance of Regulatory T cells in Influenza Infection Examination of the the role of CD4+CD25+ regulatory T cells during the course of an influenza infection using a combination of regulatory T cell depletion and adoptive transfer experiments.

Factors Governing Regulatory T Cell Activation and Function: Showed that regulatory T cell suppressor function can be mediated through a partial T cell receptor signal.  Regulatory T cell suppressor function can mediate the suppression of T cell proliferation, cytokine production, and memory B cell antibody production.

• Generated regulatory and conventional CD4 T cell primary cell lines from TCR transgenic mice.
• Maintained colony of TCR transgenic mice- responsible for mating decisions.
• Analyzed the capacity of regulatory T cells to become skewed to TH1/TH2 phenotypes using cytokine ELISAs and intracellular staining.
• Characterized the phenotype of regulatory T cells through flow cytometry.
• Measured the capacity of Altered Peptide ligands (APL) to activate CD4 T cells by 3H thymidine incorporation and CFSE analysis.
• Analyzed the capacity of APL activated regulatory T cells to inhibit T cell proliferation in vitro.
• Showed that regulatory T cells can inhibit memory B cell responses by in vivo transfer followed by ELISA and ELISPOT analysis.

Research Assistant, Laboratory of Dr. Howard M. Johnson, Ph.D., 1996-2000, University of Florida, Department of Microbiology and Cell Science
Gainesville, FL.
Role of the Interferon gamma/Interferon Gamma Receptor Complex in Signal Transduction
We showed that the interferon gamma/interferon gamma receptor alpha chain was translocated to the cell nucleus with kinetics similar to that of signal transducer and activator of transcription 1a (STAT1a).  These data suggested that interferon gamma, which contains a nuclear localization signal (NLS), likely plays a role in the nuclear translocation of STAT1a, a protein necessary for the activation of CD4 T cells.

• Conducted protein binding studies to analyze the affinity of iodinated interferon gamma (IFN g) to the intracellular domain of the interferon gamma receptor.
• Responsible for the maintenance of human cell lines.
• Performed nuclear import assays with permeabilized HeLa cells to illustrate the presence of two NLS sequences in human interferon gamma.
• Interferon gamma devoid of primary NLS sequence was expressed in E. coli and purified in order to show its necessity in biological function.
• The nuclear translocation of interferon gamma/interferon gamma receptor was observed through a combination of immuno-florescence, electron microscopy, western blotting, and immuno-precipitation.

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Honors and Awards

The Association of Medical Laboratory Immunologists Travel Award Recipient 2006.
Keystone Symposia Travel Award Recipient 2005.
The Graduate School at the University of Florida Pre-doctoral Fellow 1998-2000.
IFAS Pre-doctoral Minority Fellow, University of Florida 1996-1998.

Publications

Green MM., Larkin J 3rd., Subramaniam PS., Szente BE., and Johnson HM. (1998) Human IFN gamma receptor cytoplasmic domain: expression and interaction with HuIFN gamma. Biochemical & Biophysical Research Communications. 243(1):170-6.

Johnson HM., Torres BA., Green MM., Szente BE., Siler KI., Larkin J 3rd., and Subramaniam PS. (1998) Cytokine-receptor complexes as chaperones for nuclear translocation of signal transducers. Biochemical & Biophysical Research Communications. 244(3):607-14.

Johnson HM., Torres BA., Green MM., Szente BE., Siler KI., Larkin J 3rd., and Subramaniam PS. (1998) Hypothesis: ligand/receptor-assisted nuclear translocation of STATs. Proceedings of the Society for Experimental Biology & Medicine. 218(3):149-55.

Larkin J 3rd., Johnson HM., and Subramaniam PS. (2000) Differential nuclear localization of the IFNGR-1 and IFNGR-2 subunits of the IFN-gamma receptor complex following activation by IFN-gamma. Journal of Interferon & Cytokine Research. 20(6):565-76.

Subramaniam PS., Larkin J 3rd., Mujtaba MG., Walter MR., and Johnson HM. (2000) The COOH-terminal nuclear localization sequence of interferon gamma regulates STAT1 alpha nuclear translocation at an intracellular site. Journal of Cell Science. 113 ( Pt 15):2771-81.

Larkin J 3rd., Subramaniam PS., Torres BA., and Johnson HM. (2001) Differential properties of two putative nuclear localization sequences found in the carboxyl-terminus of human IFN-gamma. Journal of Interferon & Cytokine Research. 21(6):341-8.

Subramaniam PS., Green MM., Larkin J 3rd., Torres BA., and Johnson HM. (2001) Nuclear translocation of IFN-gamma is an intrinsic requirement for its biologic activity and can be driven by a heterologous nuclear localization sequence. Journal of Interferon & Cytokine Research. 21(11):951-9.

Cozzo C., Larkin J 3rd and Caton AJ. (2003) Cutting edge: self peptides drive the peripheral expansion of CD4+CD25+ regulatory T cells. J Immunol.  171(11):5678-82.

Lerman MA., Larkin J 3rd, Cozzo C., Jordan MS., and Caton AJ. (2004) CD4+CD25+ regulatory T cell repertoire formation in response to varying expression of a neo-self antigen. J Immunol. 173(1): 236-44.

Caton AJ., Cozzo C., Larkin J 3rd., Lerman MA., Boesteanu A., and Jordan MS. (2004) CD4+CD25+ Regulatory T cells Selection. Ann NY Acad Sci. 1029:101-14.

Villarino AV., Larkin J 3rd, Saris CJM., Caton AJ., Lucas S., Wong T., deSauvage FJ., and Hunter CA. (2005) Positive and Negative Regulation of the IL-27 Receptor during Lymphoid Cell Activation.  J Immunol. 174(12): 7684-91.

Cozzo C., Lerman MA., Boesteanu A., Larkin J 3rd., Jordan MS., and Caton AJ. (2005) Selection of CD4+CD25+ regulatory T cells by self-peptides Curr Top Microbiol Immunol. 293:3-23.

Cozzo C., Larkin J. 3rd., Boesteanu A., Lerman MA., Rankin AL., and Caton AJ. (2006) Role of TCR specificity in CD4+CD25+ regulatory T cell selection. Immunol Rev. 212:74-85.

Larkin J 3rd, Picca CC., and Caton AJ. (2007) Activation of CD4+CD25+ regulatory T cell suppressor function by analogs of the selecting peptide.  Eur J Immunol. 37(1): 139-46.

Guay HM., Larkin J 3rd, Picca CC., and Caton AJ. (2007) Spontaneous auto-reactive memory B cell formation driven by a high frequency of auto-reactive CD4+ T cells. J Immunol. In press.

Rankin AL., Reed AJ., Picca CC., Boesteanu A., Guay HM., Oh S., Larkin J 3rd., Aitken MK., Panarey L., Koeberlein B., Lipsky P., Tomaszewski JE., Naji A., and Caton AJ. (2007) CD4+ T cell repertoire dictates disease penetrance in a mouse model of autoimmune arthritis. Submitted.

Larkin J 3rd, Rankin AL., Picca CC., Sant AJ., and Caton AJ. (2007) Naturally occurring CD4+CD25+ regulatory T cell selection is dominated by TCR specificity for self-peptides within the thymus. Manuscript in preparation.

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