Department of Chemistry and Biochemistry

Faculty: Ajith Karunarathne, Ph.D.



Associate Professor
Office: BO 2098 A/B
Phone: (419) 530-7880
Fax: (419) 530-4033

Professional Background:
B.S.: University of Sri Jayewardenepura, Sri Lanka
PhD.: Michigan State University, East Lansing, Michigan, USA
Postdoctoral: Washington University School of Medicine, St. Louis, Missouri, USA

Group Page   |   Twitter Feed   |    Publications 


CellPhotoChem lab's recently published research shows cytotoxic effects vision-chromophore Retinal and sunlight

Blue light-triggered photochemistry and cytotoxicity of retinal, Ratnayake K, Payton J. L., Meger M.E., Godage N.H., Gionfriddo E., Karunarathne A. Blue light-triggered photochemistry and cytotoxicity of retinal. Cellular Signalling. 2020 : 109547. NIHMS ID: NIHMS1556878.

CellPhotoChem Lab's Research elucidates molecular mechanisms underlying Statins (cholesterol-lowering drugs).

Statins Perturb Gβγ Signaling and Cell Behavior in a Gγ Subtype Dependent Manner., Tennakoon, M., Kankanamge, D., Senarath, K., Fasih, Z., and Karunarathne, A. (2019) Mol Pharmacol 95, 361-375.

CellPhotoChem Lab exhibits the functional duality of circadian photoreceptor melanopsin.

G protein αq exerts expression level-dependent distinct signaling paradigms., Kankanamge, D., Tennakoon, M., Weerasinghe, A., Cedeno-Rosario, L., Chadee, D. N., and Karunarathne, A. (2019) Cell Signal 58, 34-43.

CellPhotoChem Lab reviewed optical approaches for mapping cellular signaling. 

Optical approaches for single cell and subcellular analysis of GPCR-G protein signaling., Kankanamge, D., Ratnayake K, Senarath, K., Tennakoon, M., Harmon, E., and Karunarathne, A. (2019) Anal Bioanal Chem.

Samaradivakara, S., Kankanamge, D., Senarath, K., Ratnayake, K., and Karunarathne, A. (2018) G protein gamma (Ggamma ) subtype dependent targeting of GRK2 to M3 receptor by Gbetagamma. Biochemical Biophysical Research Communications, 2018 Jun 11. pii: S0006-291X(18)31295-6.

Our research named a Top 100 science paper of 2018

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Kasun Ratnayake, Ph.D. graduate student in the CELLPHOTOCHEM lab, received the award for the best oral presentation by a student at the 2018 ANACHEM Symposium on November 1 for his talk Blue Light-Sensitized Retinal Disrupts Cellular Signaling. Nice Job Kasun!

Our LATEST collaborative RESEARCH ARTICLE ON decoding calcium oscillations in neurons is just accepted at  ACS Chemical Neuroscience. part of the work was performed  IN . CONGRATULATIONS TO AUTHORS! 

Swain, S., Gupta, R. K., Ratnayake, K., Priyanka, P., Singh, R., Jana, S., Mitra, K., Karunarathne, A., Giri, L., (2018). Confocal imaging and k-means clustering of GABAB and mGluR mediated modulation of Ca2+ spiking in hippocampal neurons. ACS Chemical Neuroscience.

The latest research article on mechanisms of Blue light-induced cellular toxicity from my research group at in . CONGRATULATIONS TO AUTHORS! 

Ratnayake, K., Payton, J. L., Lakmal, O. H., and Karunarathne, A. (2018) Blue light excited retinal intercepts cellular signaling. Scientific Reports 8, 10207 


Samaradivakara, S., Kankanamge, D., Senarath, K., Ratnayake, K., and Karunarathne, A. (2018) G protein gamma (Ggamma ) subtype dependent targeting of GRK2 to M3 receptor by Gbetagamma. Biochemical Biophysical Research Communications, 2018 Jun 11. pii: S0006-291X(18)31295-6.

Two latest publications from our group just appeared online. Congratulations to the authors! 

Kankanamge, D., Ratnayake, K., Samaradivakara, S., and Karunarathne, A. (2018). Melanopsin (Opn4) employs Gαi and Gβγ as major signal transducers. Journal of Cell Science.

Senarath, K.; Kankanamge, D.; Samaradivakara, S.; Ratnayake, K.; Tennakoon, M.; Karunarathne, A. (2018). Regulation of G Protein βγ Signaling. International Review of Cell and Molecular Biology.


Senarath, K., Payton, J. L., Kankanamge, D., Siripurapu, P., Tennakoon, M., and Karunarathne, A. (2018) Gγ identity dictates efficacy of Gβγ signaling and macrophage migration. Journal of Biological Chemistry 2018; 293(8):2974-2989.

Year 2017 publications from our lab:

  1. Siripurapu, P.; Kankanamge, D.; Ratnayake, K.; Senarath, K.; Karunarathne, A. J Biol Chem 2017, 292, 17482-17495.

  2. Ratnayake, K.; Kankanamge, D.; Senarath, K.; Siripurapu, P.; Weis, N.; Tennakoon, M.; Payton, J. L.; Karunarathne, A. Methods in cell biology 2017, 142, 1-25.

  3. Gupta, R. K.; Swain, S.; Kankanamge, D.; Priyanka, P. D.; Singh, R.; Mitra, K.; Karunarathne, A.; Giri, L. SLAS discovery 2017, 2472555217693378.

Our findings on itch sensation are now published in the journal SCIENCE SIGNALING. Click here to read it. Click here to read the UT news article on this research.

Our review article Titled " Subcellular optogenetics: controlling signaling and single cell behavior" is published in JOURNAL OF CELL SCIENCES. Click here to read the article.

Our findings are published in the journal NEURON on cross-talks between Serotonin (5HT)- gastrin-releasing peptide (GRP) receptors and subsequent effects on itch sensation. This new is on NBC news national coverage.

Click here watch NBC Brian Williams talking about this work. NBC news

Click here to read this article.

Exciting undergraduate and graduate research opportunities!

We offer a science outreach program for high school students to conduct research in life sciences!

Please contact Dr. Ajith Karunarathne for more information.

Research Interests:

Bioanalytical, Optical chemistry and Optogenetics, Molecular Imaging, and Signal Transduction

1. GPCR and G protein signaling in immune and cancer cell migration.
2. Engineering optogenetic approaches to control subcellular signaling.
3. Engineering of biosensors and assay to quantify dynamic behaviors of signaling molecules.
4. Experiment-guided mathematical-computations modeling of cellular signaling networks.
5. Functional characterization opsin for their ability to control mammalian cell signaling.
6. Optical isomerization of push-pull molecules and the applicability in biomedical research.

Research Synopsis:

Quantitative visualization of signaling in living cells surpasses cell disruptive approaches by providing spatiotemporal information about molecular entities that govern complex cellular processes. However, there is a lack of approaches that govern signaling in a cell with precise spatial and temporal control to complement the existing assortment of live cell imaging methodologies.
To bridge the above gap, research in our group interfaces chemistry and biology with an emphasis on understanding signaling network dynamics in living cells. In order to do this, we employ optical approaches not only to visualize but also to control and interrogate signaling in single cells. We currently dissect several pathologically important cell behaviors such as cell migration in cancer and neuronal damage repair. To facilitate this process, we generate tools of two kinds using a combination of chemical, genetic engineering, and molecular biology approaches. First, we design optical triggers to govern entire or individual components of signaling pathways in sub-cellular regions of single cells using specific wavelengths of light. Second, we develop efficient sensors to probe the dynamics of signaling molecules through fluorescence localization, bioluminescence or Förster resonance energy transfer (BRET or FRET) techniques.
Using optical tools, we interrogate cell behaviors by activating, inhibiting or modulating single, or multiple signaling modalities and simultaneously quantify the dynamics of the associated cellular and molecular responses. To perform these experiments, we employ single & multi-photon optogenetics and imaging approaches in combination with two and three-dimensional microfluidic technologies and classical analytical instrumentation. Additionally, we make use of a multiphoton confocal approach to perform intravital optogenetics and imaging to control and visualize single-cell behaviors in-vivo. These approaches will help us identify and understand molecules, mechanisms and their dynamics in signaling networks that control cellular processes such as cancer metastasis, demyelination in the nervous system and modulation of itch sensation. Our approaches can be used to optically control a variety of cellular signaling and behavioral processes in a whole animal as therapeutic strategies. 
Last Updated: 6/27/22