The lens depends for its function on the accumulation of large amounts of a modest number of proteins. These include cytoplasmic crystallins, specialized membrane proteins and intermediate filaments. For more than thirty years it has been assumed that the genes encoding these proteins are """"""""turned on"""""""" during the formation of lens fiber cells, the cells that make up the bulk of the lens. However, the data presented in this proposal show that the RNAs encoding these """"""""fiber-specific"""""""" proteins are synthesized early in lens formation and are present in the progenitor cells of the lens, the lens epithelial cells, throughout life. Since these mRNAs are present, but the proteins that they encode are not, there must be mechanisms that determine when and in what cells these mRNAs are translated into protein. Our data suggest that selective translation of these mRNAs is governed by protein-RNA complexes called RNA granules (RGs). We propose to identify the major genes that are regulated in the lens by post-transcriptional mechanisms, determine the RG components and RNA sequences required to regulate the expression of an abundant lens membrane protein, MIP, and to identify the lens-specific RG components that are responsible for the selective translation of the """"""""fiber cell-specific"""""""" mRNAs throughout lens development and in postnatal life. We expect that these studies will define a new paradigm for lens gene expression and will serve as a model for post-transcriptional regulation of gene expression in other tissues. Since mutation of one lens-specific RG component, TDRD7, causes human cataracts, these studies will also provide fundamental information about cataract formation.

Public Health Relevance

Cataracts are the leading cause of blindness worldwide. Preserving lens transparency would, therefore, have major public health implications. To preserve transparency, one must understand the reasons that the lens is transparent in the first place. Substantial research has shown that the proteins that accumulate in the lens to very high levels, the lens crystallins, are required for the refractive properties and transparency of the lens. Until recently, it has been thought that the accumulation of crystallin proteins is regulated by differential gene transcription (messenger RNA synthesis). Our data show that this is only partially correct. We found that many crystallin genes are expressed as messenger RNAs in all lens cells, but these messenger RNAs are not translated into proteins. Therefore, a major component of the lens that is required for its function is regulated by a previously unsuspected mechanism. The purpose of this proposal is to understand the mechanisms that regulate mRNA translation in the lens. These studies will identify causes of hereditary cataracts, lead to a better understanding of how differential gene expression assures lens transparency and how gene expression might be regulated to preserve lens function.

Agency
National Institute of Health (NIH)
Institute
National Eye Institute (NEI)
Type
Research Project (R01)
Project #
5R01EY021505-03
Application #
8445324
Study Section
Anterior Eye Disease Study Section (AED)
Program Officer
Araj, Houmam H
Project Start
2011-04-01
Project End
2015-03-31
Budget Start
2013-04-01
Budget End
2014-03-31
Support Year
3
Fiscal Year
2013
Total Cost
$454,092
Indirect Cost
$155,347
Name
Washington University
Department
Ophthalmology
Type
Schools of Medicine
DUNS #
068552207
City
Saint Louis
State
MO
Country
United States
Zip Code
63130
Anand, Deepti; Lachke, Salil A (2016) Systems biology of lens development: A paradigm for disease gene discovery in the eye. Exp Eye Res :
Zhang, Ying; Fan, Jieqing; Ho, Joshua W K et al. (2016) Crim1 regulates integrin signaling in murine lens development. Development 143:356-66
Audette, Dylan S; Anand, Deepti; So, Tammy et al. (2016) Prox1 and fibroblast growth factor receptors form a novel regulatory loop controlling lens fiber differentiation and gene expression. Development 143:318-28
Dash, Soma; Siddam, Archana D; Barnum, Carrie E et al. (2016) RNA-binding proteins in eye development and disease: implication of conserved RNA granule components. Wiley Interdiscip Rev RNA 7:527-57
Dash, Soma; Dang, Christine A; Beebe, David C et al. (2015) Deficiency of the RNA binding protein caprin2 causes lens defects and features of peters anomaly. Dev Dyn 244:1313-27
Terrell, Anne M; Anand, Deepti; Smith, Sylvie F et al. (2015) Molecular characterization of mouse lens epithelial cell lines and their suitability to study RNA granules and cataract associated genes. Exp Eye Res 131:42-55
Anand, Deepti; Agrawal, Smriti; Siddam, Archana et al. (2015) An integrative approach to analyze microarray datasets for prioritization of genes relevant to lens biology and disease. Genom Data 5:223-227
Agrawal, Smriti A; Anand, Deepti; Siddam, Archana D et al. (2015) Compound mouse mutants of bZIP transcription factors Mafg and Mafk reveal a regulatory network of non-crystallin genes associated with cataract. Hum Genet 134:717-35
Manthey, Abby L; Lachke, Salil A; FitzGerald, Paul G et al. (2014) Loss of Sip1 leads to migration defects and retention of ectodermal markers during lens development. Mech Dev 131:86-110
Manthey, Abby L; Terrell, Anne M; Lachke, Salil A et al. (2014) Development of novel filtering criteria to analyze RNA-sequencing data obtained from the murine ocular lens during embryogenesis. Genom Data 2:369-374

Showing the most recent 10 out of 14 publications