Autophagy is a conserved, eukaryotic, cellular pathway responsible for the sequestration and degradation of intracellular macromolecules and macromolecular assemblies that are unnecessary, defective or harmful to cells. BECN homologs are highly conserved in eukaryotes, but mammals are unique in having two functional BECN paralogs. Defects or deficiencies in BECN1-mediated autophagy are implicated in a wide range of diseases such as breast and ovarian cancer, cardiovascular diseases, embryonic defects or fatality, as well as several infectious diseases, especially those caused by viruses; while defects in BECN2 are implicated in obesity, insulin resistance and Kaposi's Sarcoma associated Herpesvirus induced oncogenicity. The interaction of a BECN protein with ATG14 is essential for autophagosome nucleation, the first committed step in autophagy. BECN and ATG14 are complex, multi-domain proteins. The interaction of ATG14 with the BECN paralogs is mediated by the coiled-coil domain (CCD) within each protein. The long-term goal of the proposed research is to understand the mechanism of BECN homologs in autophagy and cellular homeostasis. The objective of this proposal is to obtain comparative structural and mechanistic information about the CCDs of human BECN paralogs, and their interaction with ATG14, which is essential for their function in mediating autophagy via the autophagosome nucleation complex. This objective will be accomplished by the specific aims of this proposal, which are: (1) To elucidate similarities and differences between human BECN1 and BECN2 CCD homodimers. (2) To elucidate similarities and differences in the interactions of human BECN1 and BECN2 CCDs with the ATG14 CCD. A wide range of structural, biophysical, biochemical, cellular and molecular biology methods will be used to accomplish these aims. The results from this research will lead to a mechanistic understanding of the competitive recruitment of ATG14 by the BECN paralogs, thereby providing invaluable insights into their different biological roles. This comparative understanding of the structural and thermodynamic details of how each paralog self assembles and recruits binding partners is essential to understanding autophagy and cellular homeostasis.

Public Health Relevance

The interaction of ATG14 with BECN proteins (either BECN1 or BECN2 in mammals) is essential for autophagy, a cellular pathway responsible for the sequestration and degradation of intracellular macromolecules and macromolecular assemblies that are unnecessary, defective or otherwise harmful for cells. Defects or deficiencies in BECN1-mediated autophagy have been implicated in a wide range of diseases including various cancers, cardiovascular diseases, embryonic defects or fatality, as well as several infectious diseases, especially those caused by viruses; while defects in BECN2 are implicated in obesity, insulin resistance and Kaposi's Sarcoma associated Herpesvirus induced oncogenicity. This proposal aims to investigate how these proteins assemble to carry out their role in maintaining human health.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Academic Research Enhancement Awards (AREA) (R15)
Project #
1R15GM122035-01
Application #
9232857
Study Section
Macromolecular Structure and Function B Study Section (MSFB)
Program Officer
Flicker, Paula F
Project Start
2017-05-01
Project End
2020-04-30
Budget Start
2017-05-01
Budget End
2020-04-30
Support Year
1
Fiscal Year
2017
Total Cost
Indirect Cost
Name
North Dakota State University
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
803882299
City
Fargo
State
ND
Country
United States
Zip Code
58108
Glover, Karen; Li, Yue; Mukhopadhyay, Shreya et al. (2017) Structural transitions in conserved, ordered Beclin 1 domains essential to regulating autophagy. J Biol Chem 292:16235-16248
Su, Minfei; Li, Yue; Wyborny, Shane et al. (2017) BECN2 interacts with ATG14 through a metastable coiled-coil to mediate autophagy. Protein Sci 26:972-984
Mei, Yang; Glover, Karen; Su, Minfei et al. (2016) Conformational flexibility of BECN1: Essential to its key role in autophagy and beyond. Protein Sci 25:1767-85