John Hepler, PhD

Professor

Emory University School of Medicine

Office: G205 Biochemistry Connector

Phone: 404-727-3641

Fax: 404-727-0365

Email: jhepler@emory.edu

Additional Contact Information

Mailing Address:

Emory University School of Medicine

G205 Biochemistry Connector - Rollins Research Center
1510 Clifton Road

Atlanta, Georgia 30322-3090

Additional Websites

Education

  • PhD, Neurobiology, University of North Carolina at Chapel Hill, 1988
  • Postdoctoral Fellow, Department of Pharmacology, University of North Carolina at Chapel Hill, 1988-1989
  • Postdoctoral Fellow, Department of Pharmacology, University of Texas Southwestern Medical Center, 1989-94
  • Instructor, Department of Pharmacology, University of Texas Southwester Medical Center, 1994-96
  • Emory University, 1996

Biography

Research Area:
Cellular roles and regulation of novel signaling proteins/pathways used by neurotransmitters
Research Interests:
The general understanding of how neurotransmitters, hormones and sensory input (light, taste, smell) exert their actions on target cells and tissues has undergone fundamental changes in recent years. Established models suggest that these extracellular stimuli rely upon a G protein coupled receptor(GPCR), a heterotrimeric guanine nucleotide binding regulatory protein(G protein), and a limited number of well described downstream effector proteins that produce second messengers (e.g. adenylyl cyclases, phospholipases, ion channels). However, recent studies (including our own) indicate that neurotransmitter GPCR and G proteins engage a growing list of newly appreciated yet poorly understood proteins and linked signaling pathways to carry out their cellular functions. We have recent evidence that certain closely related G proteins, previously thought to be functionally equivalent, engage multiple novel signaling proteins and pathways to elicit unique profiles of divergent cellular responses in a cell specific manner (e.g. stimulated differentiation in one cell type, and apoptosis/cell death in another). Ongoing studies in the lab focus on identifying involved novel proteins and linked signaling pathways. Most prominent among these novel G protein binding partners are the regulators of G protein signaling (RGS proteins). RGS proteins are a large family (> 30 members) of highly diverse, multifunctional signaling proteins that bind directly to neurotransmitter-activated G proteins to modulate G protein signaling capacity. RGS proteins differ widely in their overall size and amino acid identity, and many possess a remarkable variety of structural domains and motifs that regulate their actions and/or enable them to interact with novel protein binding partners with poorly defined cellular roles. Ongoing projects include understanding: 1) roles for RGS as direct modulators and integrators of G protein signaling, 2) how RGS link G proteins to novel signaling proteins and pathways involved in neuronal differentiation, 3) how RGS bind selectively to certain hormone/neurotransmitter receptors to modulate their signaling functions and/or serve as functional scaffolds to recruit additional signaling proteins, and 4) how neurotransmitter-stimulated phosphorylation of RGS alters RGS function and subcellular localization. General Research Interests: Our laboratory studies cellular roles and regulation of novel signaling proteins and pathways used by neurotransmitters and hormones to exert their actions on target cells. To address these questions, we combine multidisciplinary approaches including modern techniques in cell biology, molecular biology, and protein biochemistry.

Publications