Jason MacGurn, Ph.D.

Assistant Professor

Faculty Appointments
Assistant Professor of Cell and Developmental Biology
Ph.D., Biochemistry , University of California, San Francisco, CaliforniaB.A., University of Chicago, Chicago, Illinois
Research Description

Eukaryotic cells respond to environmental cues by remodeling the cell surface, a process that relies on the targeted removal and degradation of plasma membrane (PM) proteins. This turnover process begins when a transmembrane PM protein (or "cargo") is ubiquitinated, a modification that is recognized by the endocytic machinery and sorted into vesicles. By targeting PM proteins for endocytosis, the cargo ubiquitination machinery directly regulates signaling processes, ion and nutrient homeostasis, stress responses, and protein quality control at the PM. Given that these processes are critical for cell growth and differentiation, it is not surprising that many human disease states, including various cancers, are associated with defects in PM protein turnover.

<b>Research Objective</b>

The main research objective of my lab is to understand the molecular mechanisms that regulate the composition of proteins at the plasma membrane and to engineer new technologies for artificial remodeling of the cell surface.

<b>Cell Surface Remodeling in Yeast</b>

In yeast, ubiquitin-mediated endocytosis is regulated almost exclusively by a ubiquitin ligase called Rsp5, a member of the Nedd4 family ubiquitin ligases. Rsp5 substrate selection is mediated by a modular adaptor network of proteins called ARTs which function to target Rsp5 ubiquitin ligase activity to specific substrates at the cell surface. My lab is focused on understanding (i) the molecular mechanisms that govern regulation of the ART-Rsp5 network and (ii) the biochemical and structural basis of ART-mediated cargo recognition. By dissecting the molecular mechanisms that drive cell surface remodeling in yeast, we hope to better understand cellular strategies for management of biological complexity.

<b>Cell Surface Remodeling in Human Disease</b>

The human genome encodes nine Nedd4 family ubiquitin ligases and many of these have been linked to various human diseases, including cancer. Despite their relevance to human disease, the biological function of many of these ubiquitin ligases is not well understood. Preliminary experiments indicate that networks of adaptor proteins, similar to the ART proteins in yeast, may function to target Nedd4 ubiquitin ligases to specific PM substrates. By characterizing the molecular mechanisms that govern the targeting of Nedd4 ubiquitin ligases in normal and disease states, we aim to develop new technologies that alter cell surface protein composition and explore these as potential tools for therapeutic intervention.
Research Keywords
Investigating molecular mechanisms of membrane protein turnover and cell surface remodeling programs in normal and disease states
Zhao Y, Macgurn JA, Liu M, Emr S. The ART-Rsp5 ubiquitin ligase network comprises a plasma membrane quality control system that protects yeast cells from proteotoxic stress. Elife. 2013; 2: e00459. PMID: 23599894, PMCID: PMC3628405, PII: 00459, DOI: 10.7554/eLife.00459, ISSN: 2050-084X.

Manford AG, Stefan CJ, Yuan HL, Macgurn JA, Emr SD. ER-to-plasma membrane tethering proteins regulate cell signaling and ER morphology. Dev. Cell. 2012 Dec 12/11/2012; 23(6): 1129-40. PMID: 23237950, PII: S1534-5807(12)00524-2, DOI: 10.1016/j.devcel.2012.11.004, ISSN: 1878-1551.

Ling Y, Stefan CJ, Macgurn JA, Audhya A, Emr SD. The dual PH domain protein Opy1 functions as a sensor and modulator of PtdIns(4,5)P2 synthesis. EMBO J [print-electronic]. 2012 Jun 6/29/2012; 31(13): 2882-94. PMID: 22562153, PMCID: PMC3395088, PII: emboj2012127, DOI: 10.1038/emboj.2012.127, ISSN: 1460-2075.

MacGurn JA, Hsu PC, Emr SD. Ubiquitin and membrane protein turnover: from cradle to grave. Annu. Rev. Biochem [print-electronic]. 2012; 81: 231-59. PMID: 22404628, DOI: 10.1146/annurev-biochem-060210-093619, ISSN: 1545-4509.

MacGurn JA, Hsu PC, Smolka MB, Emr SD. TORC1 regulates endocytosis via Npr1-mediated phosphoinhibition of a ubiquitin ligase adaptor. Cell. 2011 Nov 11/23/2011; 147(5): 1104-17. PMID: 22118465, PII: S0092-8674(11)01271-2, DOI: 10.1016/j.cell.2011.09.054, ISSN: 1097-4172.

Lin CH, MacGurn JA, Chu T, Stefan CJ, Emr SD. Arrestin-related ubiquitin-ligase adaptors regulate endocytosis and protein turnover at the cell surface. Cell [print-electronic]. 2008 Nov 11/14/2008; 135(4): 714-25. PMID: 18976803, PII: S0092-8674(08)01182-3, DOI: 10.1016/j.cell.2008.09.025, ISSN: 1097-4172.

McLaughlin B, Chon JS, MacGurn JA, Carlsson F, Cheng TL, Cox JS, Brown EJ. A mycobacterium ESX-1-secreted virulence factor with unique requirements for export. PLoS Pathog. 2007 Aug 8/3/2007; 3(8): e105. PMID: 17676952, PMCID: PMC1937011, PII: 07-PLPA-RA-0093, DOI: 10.1371/journal.ppat.0030105, ISSN: 1553-7374.

MacGurn JA, Cox JS. A genetic screen for Mycobacterium tuberculosis mutants defective for phagosome maturation arrest identifies components of the ESX-1 secretion system. Infect. Immun [print-electronic]. 2007 Jun; 75(6): 2668-78. PMID: 17353284, PMCID: PMC1932882, PII: IAI.01872-06, DOI: 10.1128/IAI.01872-06, ISSN: 0019-9567.

Greenstein AE, MacGurn JA, Baer CE, Falick AM, Cox JS, Alber T. M. tuberculosis Ser/Thr protein kinase D phosphorylates an anti-anti-sigma factor homolog. PLoS Pathog. 2007 Apr; 3(4): e49. PMID: 17411339, PMCID: PMC1847690, PII: 06-PLPA-RA-0318R3, DOI: 10.1371/journal.ppat.0030049, ISSN: 1553-7374.

MacGurn JA, Raghavan S, Stanley SA, Cox JS. A non-RD1 gene cluster is required for Snm secretion in Mycobacterium tuberculosis. Mol. Microbiol. 2005 Sep; 57(6): 1653-63. PMID: 16135231, PII: MMI4800, DOI: 10.1111/j.1365-2958.2005.04800.x, ISSN: 0950-382X.

Available Postdoctoral Position Details
Posted: 8/15/2013
Interested individuals should inquire via e-mail about postdoctoral research opportunities available in the MacGurn Lab.