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Megan A. Rizzo, PhD

Academic Title:

Associate Professor

Primary Appointment:



660 West Redwood St., HH 525B

Phone (Primary):

(410) 706-2421


(410) 706-8341

Education and Training

  • Associate Professor, Department of Physiology, 2013-present 
  • Assistant Professor, Department of Physiology, 2005-2013
  • Postdoctoral Fellow, Vanderbilt University, 2000-2005
  • PhD, University of Pittsburgh, 2000 BA, Canisius College, 1996

Highlighted Publications

Markwardt ML, Seckinger KM, Rizzo MARegulation of Glucokinase by Intracellular Calcium Levels in Pancreatic Beta CellsJ Biol Chem. 291: 3000-3009 2016. PMID: 26698632

Desmond PF, Muriel J, Markwardt ML, Rizzo MA, Bloch RJ. Identification of Small Ankyrin 1 as a Novel Sarco(endo)plasmic Reticulum Ca2+-ATPase 1 (SERCA1) Regulatory Protein in Skeletal MuscleJ Biol Chem 290(46):27854-67 2015 PMCID: PMC4646913

Costantini LM, Baloban M, Markwardt ML, Rizzo MA, Guo F, Verkhusha VV, Snapp EL. A palette of fluorescent proteins optimized for diverse cellular environments. Nat Commun. 6:7670 2015 PMCID: PMC4499870

Fairfax ST, Mauban JR, Hao S, Rizzo MA, Zhang J, Wier WG. Ca(2+) signaling in arterioles and small arteries of conscious, restrained, optical biosensor mice. Front Physiol. 2014 Oct 7;5:387. doi: 10.3389/fphys.2014.00387. eCollection 2014.  PMCID: PMC4188025

Mauban JR, Fairfax ST, Rizzo MA, Zhang J, Wier WG. A method for noninvasive longitudinal measurements of [Ca2+] in arterioles of hypertensive optical biosensor mice. Am J Physiol Heart Circ Physiol. 2014 Jul 15;307(2):H173-81. doi: 10.1152/ajpheart.00182.2014. Epub 2014 May 23.  PMCID: PMC4101644

Additional Publication Citations

Markwardt ML, Nkobena A, Ding SY, & Rizzo MAAssociation with nitric oxide synthase on insulin secretory granules regulates glucokinase protein levelsMol Endocinol. 26:1617-29. 2012. PMCID: PMC3434526

Ding SY, Nkobena A, Kraft CA, Markwardt ML & Rizzo MAGlucagon-like peptide 1 stimulates post-translational activation of glucokinase in pancreatic beta cellsJ. Biol. Chem. 286:16768-42. 2011. PMCID: PMC3089519

Markwardt ML, Kremers GK, Kraft CA, Ray K, Cranfill PJC, Wilson KA, Day RN, Wachter RM, Davidson MW & Rizzo MAAn improved Cerulean Fluorescent protein with enhanced brightness and reduced reversible photoswitchingPLoS ONE6:e17896. 2011. PMCID: PMC3066204

Ding SY, Tribble ND, Kraft CA, Markwardt M, Gloyn AL & Rizzo MANaturally occurring glucokinase mutations are associated with defects in post-translational S-nitrosylationMol Endocrinol. 24:171-7. 2010. PMCID: PMC2802892

Rizzo MA. & Piston D.W. FRET by Fluorescence Polarization Microscopy Sullivan K.F. (ed). Methods in Cell Biology. 85:415-30. 2008.

Rizzo MA, Springer G, Segawa K, Zipfel W & Piston DW. Optimization of pairings and detection conditions for measurement of FRET between cyan and yellow fluorescent proteinsMicroscopy & Microanalysis 12:238-54. 2006.

Rizzo MA & Piston DW. A High Contrast Method for Imaging FRET between Fluorescent ProteinsBiophys J. 88:L14-16. 2005 PMCID: PMC1305173

Rizzo MA. Springer GH, Granada B & Piston D. W. An improved cyan fluorescent protein variant useful for FRETNat. Biotechnol. 22:445-49. 2004. 

Rizzo MA & Piston DW. Regulation of β-cell glucokinase by S-nitrosylation and association with nitric oxide synthaseJ. Cell Biol. 161:243-48. 2003. PMCID: PMC2172922

Research Interests

Insulin secretion from the pancreas

Insulin is a primary and essential regulator of blood glucose, which provides nutrition to cells and tissues in the body. When blood glucose rises, the pancreatic β cells respond by secreting insulin, which in turn enhances glucose uptake by the cells in the body to quickly lower the blood sugar concentration to the correct level. How much and how quickly insulin is secreted is tightly regulated, and this is the focus of our research.

A key protein regulator of insulin secretion is the enzyme glucokinase. Our lab studies how glucokinase is regulated by nitric oxide, which activates glucokinase and regulates its cellular localization. This research is currently supported by a research grant from the NIDDK (R01DK077140).

In vivo imaging of vascular smooth muscle cell contraction 

Small areteries and arterioles control blood pressure and maintain a persistent state of contraction known as tone. To better understand how vasodilation and contraction are regulated in vivo, we use a quantitative biosensor imaging approach. This research is currently supported by research grants from the Office of the Director (R21OD018315) and NHLBI (R01HL122827).

Development of optical biosensors

Fluorescent proteins allow us to examine dynamic regulation of proteins in living cells. We use a structure-based approach to understand the inner workings of these reagents and to build better, brighter probes. Our latest variant, mCerulean3, is an exceptionally bright and stable cyan fluorescent protein. We also have several FRET-based probes in development that can be used to track enzyme activation in living cells through quantitative fluorescence microscopy methods. This project is presently funded by The BRAIN inititative (R01MH111527).

Grants and Contracts

R01DK077140, Regulatory Mechanisms of Insulin Secretion

R01HL122827, Creation of Optical Biosensor Mice for Longitudinal Studies of Vascular Function 

R01MH111527, Multiparametric Biosensor Imaging in Brain Slices

R21OD018315, Development of RhoA Optical Sensor Mice for Novel Vascular Smooth Muscle Studies

Links of Interest