R01AI151704

LMO2-LYL1 and the BHLH Factor Network in Pro-T Cells - Project Summary

The progression of T cell precursors from multipotency to commitment occurs after multiple cell cycles in the thymus. These early, pre-commitment cell cycles are important for expanding the precursors to generate enough pro-T cells to survive later selection events. However, the early stages are poorly understood, and it has not been clear what controls the precise trajectory of the cells' differentiation nor the timing or irreversibility of commitment when it occurs.

Genomic regulatory elements that are active after commitment tend to be characterized by motifs for basic helix-loop-helix (BHLH) E proteins, E2A or HEB, whereas those that are active before commitment have other signatures, suggesting that there is a major increase in E protein activity across this transition. In fact, the expression of E proteins is almost equally high before commitment, but our recent data show that they are occupied in substantially different roles before commitment, in complexes with other heterodimerization partners.

This proposal is based on recent evidence that the alternative complex, containing LMO2 and LYL1 dimerized with E2A or HEB, may actually be a major controller of the commitment transition in early T cells. Our recent evidence shows that expression of LMO2 and LYL1 is sufficient to make committed pro-T cells reverse their differentiation in terms of gene expression. Not only does the LMO2/LYL1/E2A complex bind to different genomic sites than E protein dimers, but also the addition of LMO2 and LYL1 to committed pro-T cells is sufficient to remove E proteins from sites that they occupy after commitment and shift them to sites that are normally active only before commitment.

The implication is that the kinetics of downregulation of LMO2 and LYL1 in normal T-cell differentiation could be vital for determining the timing of commitment and the maturation of the pro-T cells. LMO2 and LYL1 have been considered as T-lineage proto-oncogenes, but our evidence suggests a potent role in normal development. This proposal is to determine the mechanism of how this works and to test its significance for the actual developmental dynamics of normal early T cells.

Our preliminary work identifies the signature target genes affected by LMO2+LYL1 and their overlap with genes expressed in normal pro-T cells. We now propose to define: (1) the distinct molecular mechanisms that control different subsets of these signature genes, based on genome-wide mapping of the chromatin state changes caused by LMO2+LYL1/E protein complex binding as compared to pure E protein dimer binding; (2) whether endogenous LMO2/LYL1/E protein complexes indeed control differentiation kinetics and commitment of normal pro-T cells, based on acute CRISPR and monitoring in vitro and in vivo; and (3) the gene regulatory network architecture, involving factors regulated by LMO2+LYL1, through which LMO2+LYL1 exert their surprisingly broad impacts on T cell development.

The results should determine whether and how a biochemical mechanism of transcription factor heterodimerization partner switching may explain a central unsolved problem in the dynamics of T cell development.

California Institute Of Technology

TO ASSIST PUBLIC AND PRIVATE NONPROFIT INSTITUTIONS AND INDIVIDUALS TO ESTABLISH, EXPAND AND IMPROVE BIOMEDICAL RESEARCH AND RESEARCH TRAINING IN INFECTIOUS DISEASES AND RELATED AREAS, TO CONDUCT DEVELOPMENTAL RESEARCH, TO PRODUCE AND TEST RESEARCH MATERIALS. TO ASSIST PUBLIC, PRIVATE AND COMMERCIAL INSTITUTIONS TO CONDUCT DEVELOPMENTAL RESEARCH, TO PRODUCE AND TEST RESEARCH MATERIALS, TO PROVIDE RESEARCH SERVICES AS REQUIRED BY THE AGENCY FOR PROGRAMS IN INFECTIOUS DISEASES, AND CONTROLLING DISEASE CAUSED BY INFECTIOUS OR PARASITIC AGENTS, ALLERGIC AND IMMUNOLOGIC DISEASES AND RELATED AREAS. PROJECTS RANGE FROM STUDIES OF MICROBIAL PHYSIOLOGY AND ANTIGENIC STRUCTURE TO COLLABORATIVE TRIALS OF EXPERIMENTAL DRUGS AND VACCINES, MECHANISMS OF RESISTANCE TO ANTIBIOTICS AS WELL AS RESEARCH DEALING WITH EPIDEMIOLOGICAL OBSERVATIONS IN HOSPITALIZED PATIENTS OR COMMUNITY POPULATIONS AND PROGRESS IN ALLERGIC AND IMMUNOLOGIC DISEASES. BECAUSE OF THIS DUAL FOCUS, THE PROGRAM ENCOMPASSES BOTH BASIC RESEARCH AND CLINICAL RESEARCH. SMALL BUSINESS INNOVATION RESEARCH (SBIR) PROGRAM EXPANDS AND IMPROVES PRIVATE SECTOR PARTICIPATION IN BIOMEDICAL RESEARCH. THE SBIR PROGRAM INTENDS TO INCREASE AND FACILITATE PRIVATE SECTOR COMMERCIALIZATION OF INNOVATIONS DERIVED FROM FEDERAL RESEARCH AND DEVELOPMENT, TO INCREASE SMALL BUSINESS PARTICIPATION IN FEDERAL RESEARCH AND DEVELOPMENT, AND TO FOSTER AND ENCOURAGE PARTICIPATION OF SOCIALLY AND ECONOMICALLY DISADVANTAGED SMALL BUSINESS CONCERNS AND WOMEN-OWNED SMALL BUSINESS CONCERNS IN TECHNOLOGICAL INNOVATION. THE SMALL BUSINESS TECHNOLOGY TRANSFER (STTR) PROGRAM STIMULATES AND FOSTERS SCIENTIFIC AND TECHNOLOGICAL INNOVATION THROUGH COOPERATIVE RESEARCH AND DEVELOPMENT CARRIED OUT BETWEEN SMALL BUSINESS CONCERNS AND RESEARCH INSTITUTIONS, TO FOSTER TECHNOLOGY TRANSFER BETWEEN SMALL BUSINESS CONCERNS AND RESEARCH INSTITUTIONS, TO INCREASE PRIVATE SECTOR COMMERCIALIZATION OF INNOVATIONS DERIVED FROM FEDERAL RESEARCH AND DEVELOPMENT, AND TO FOSTER AND ENCOURAGE PARTICIPATION OF SOCIALLY AND ECONOMICALLY DISADVANTAGED SMALL BUSINESS CONCERNS AND WOMEN-OWNED SMALL BUSINESS CONCERNS IN TECHNOLOGICAL INNOVATION. RESEARCH CAREER DEVELOPMENT AWARDS SUPPORT THE DEVELOPMENT OF SCIENTISTS DURING THE FORMATIVE STAGES OF THEIR CAREERS. INDIVIDUAL NATIONAL RESEARCH SERVICE AWARDS (NRSAS) ARE MADE DIRECTLY TO APPROVE APPLICANTS FOR RESEARCH TRAINING IN SPECIFIED BIOMEDICAL SHORTAGE AREAS. IN ADDITION, INSTITUTIONAL NATIONAL RESEARCH SERVICE AWARDS ARE MADE TO ENABLE INSTITUTIONS TO SELECT AND MAKE AWARDS TO INDIVIDUALS TO RECEIVE TRAINING UNDER THE AEGIS OF THEIR INSTITUTIONAL PROGRAM.

93.855 - Allergy and Infectious Diseases Research

National Institute of Allergy and Infectious Diseases (NIAID) [HHS - NIH]

Pasadena, California 911250001 United States

Single Zip Code

NIH Research Project Grant (Parent R01 Clinical Trial Not Allowed) (PA-20-185)

Amendment Since initial award the total obligations have increased 417% from $589,027 to $3,042,427.