Project: Research project

Project Details


DESCRIPTION (Adapted from the Investigator's abstract): B lymphopoiesis
declines dramatically due to the aging process. In the mouse, senescence
results in decreased pre-B-cell numbers, altered pro-B-cell function, and
generation of an antibody repertoire which is critically different from that
seen in young adult mice. The investigator hypothesizes that pro-B-cells
from aged mice have altered expression of Rag-1, and Rag-2, and terminal
deoxynucleotidyl transferase (TdT) enzymes, and, consequently, altered
generation of the mu heavy chain VH repertoire. He further hypothesizes
that altered generation and diversification of the VH repertoire contributes
to diminished formation or dysfunction of the pre-B-cell receptor complex
(mu/lambda-5/V-pre-B) and subsequent failure to recruit new pre-B-cells into
mitosis. This would result in both low production of pre-B-cells and an
altered specificity repertoire in aged mice. In order to test these
hypotheses, he proposes in Specific Aim 1 to assess the regulation of
transcription and protein expression of the pre-B-cell receptor proteins mu,
lambda-5, and V-pre-B into pro-B-cells (CD43+CD25-B220+), newly formed
pre-B-cells (CD43+CD25+B220+), and late stage pre-B-cells (CD43-CD25+B220+)
isolated from aged (24 mo.) vs. young (3 mo.) BALB/c mice via fluorescence
activated cell sorting. He will also assess the capacity of these proteins
to assemble into surface membrane associated pre-B-cell receptors by
utilizing surrogate light chain and pre-B-cell receptor complex specific
monoclonal antibody staining and analysis of pre-B-cell receptor assembly
and turn-over in A-MuLV pre-B-cell lines from young vs. aged mice. The
capacity of aged pre-B-cell receptor expression to functionally affect the
expression of Rag-1 and Rag-2; TdT; the protein tyrosine kinase Blk; and the
expression of ^X5 itself will be assessed. In Specific Aim 2, the
pre-B-cell receptor dependent selection of the mu heavy chain repertoire
will be evaluated in nascent pre-B-cells (CD43+CD25+B220+) vs. later
(post-selection) pre-B-cells (CD43- CD25+B220+) from aged vs. young mice
with particular emphasis on diversity in CDR3. In Specific Aim 3, the
importance of the bone marrow microenvironment of aged mice in dictating the
changes observed in B lineage cell development will be investigated using
both in vivo adoptive transfer models and in vitro stroma cell culture
systems. The experiments in this application will provide a cellular and
molecular basis for understanding the temporal loss of B lymphopoiesis and
altered generation of VH repertoire during senescence.
Effective start/end date4/1/983/31/04


  • National Institute on Aging: $60,600.00
  • National Institute on Aging
  • National Institute on Aging: $263,541.00
  • National Institute on Aging
  • National Institute on Aging: $255,866.00
  • National Institute on Aging
  • National Institute on Aging: $323,117.00


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