During mammalian erythropoiesis, erythroid progenitors differentiate into erythroblasts, followed by the removal of the nucleus and organelles to develop into mature erythrocytes. Although the morphological changes associated with different stages of erythropoiesis have been well characterized, the precise molecular mechanisms governing these processes remain to be determined. A Bcl-2 family member, Nix/Bnip3L, has been found to regulate mitochondrial clearance in differentiating erythroid cells. In Nix-deficient red blood cells, the formation of autophagosomes proceeded normally. However, the sequestration of mitochondria into autophagosomes was defective. Experiments are proposed to test the hypothesis that Nix regulates the targeting of mitochondria into autophagosomes for clearance during terminal erythroid differentiation, and erythrocytes with abnormal retention of mitochondria due to defective mitochondrial autophagy are prone to oxidative stress, leading to increased cell turnover and hemolytic anemia.
Aim 1. The hypothesis that Nix is required for the mitochondrial autophagy, but not other aspects of erythroid maturation, will be studied using mice deficient in Nix or autophagy and erythroleukemic cell line.
Aim 2. Whether erythrocytes deficient in mitochondrial autophagy are more susceptible to oxidative stress-induced apoptosis will be examined.
Aim 3. Downstream molecules mediating Nix-induced mitochondrial autophagy will be studied using immunoprecipitation and proteomics approach. Defects in erythroid maturation have been found to be associated with anemia. By determining the molecular regulation of mitochondrial autophagy responsible for mitochondrial removal during erythroid maturation, we will gain insights into the regulation of erythropoiesis under both normal and disease settings. This will lead to better understanding of the pathogenesis of hemotological disorders associated with defective erythroid maturation. It may also facilitate the development of therapeutic approaches to treat these disorders.

Public Health Relevance

This project seeks to investigate molecular regulation of mitochondrial autophagy during erythroid maturation. This will help gain insights into the regulation of erythropoiesis under both normal and disease settings. The proposed studies may lead to better understanding of the pathogenesis of hemotological disorders associated with defective erythroid maturation.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK083164-04
Application #
8208215
Study Section
Hematopoiesis Study Section (HP)
Program Officer
Bishop, Terry Rogers
Project Start
2009-01-15
Project End
2013-12-31
Budget Start
2012-01-01
Budget End
2012-12-31
Support Year
4
Fiscal Year
2012
Total Cost
$263,280
Indirect Cost
$91,762
Name
Baylor College of Medicine
Department
Pathology
Type
Schools of Medicine
DUNS #
051113330
City
Houston
State
TX
Country
United States
Zip Code
77030
Chen, Min; Hong, Monica Jeongsoo; Sun, Huanhuan et al. (2014) Essential role for autophagy in the maintenance of immunological memory against influenza infection. Nat Med 20:503-10
Guerrero, Alan D; Welschhans, Robert L; Chen, Min et al. (2013) Cleavage of anti-apoptotic Bcl-2 family members after TCR stimulation contributes to the decision between T cell activation and apoptosis. J Immunol 190:168-73
Chen, Min; Huang, Lily; Wang, Jin (2013) Analyses of programmed cell death in dendritic cells. Methods Mol Biol 979:51-63
Chen, Min; Felix, Kumar; Wang, Jin (2012) Critical role for perforin and Fas-dependent killing of dendritic cells in the control of inflammation. Blood 119:127-36
Chen, Min; Felix, Kumar; Wang, Jin (2011) Immune regulation through mitochondrion-dependent dendritic cell death induced by T regulatory cells. J Immunol 187:5684-92
Chen, Min; Wang, Jin (2010) Programmed cell death of dendritic cells in immune regulation. Immunol Rev 236:11-27
Chen, Min; Sandoval, Hector; Wang, Jin (2008) Selective mitochondrial autophagy during erythroid maturation. Autophagy 4:926-8