PROJECT 2: BARBARA GAWRONSKA-KOZAK, Ph.D.
Assistant Professor | View Bio
Mentor: Jeffrey M. Gimble, M.D., Ph.D.

ABSTRACT

Commitment of adult stem cells into the adipocyte lineage

Barbara Gawronska-Kozak, Ph.D.

Weight gain associated with obesity is characterized by an increase in adipose mass that is achieved by two processes: hypertrophy and hyperplasia. Although the cascade of molecular events during the adipogenic differentiation has been generally described for cell cultures, the identity of precursor cells for the adipolineage remains to be elucidated. In this proposal we investigate adipogenesis from uncommitted adult stem cells to adipocytes. There are two specific aims in this proposal:

1. Determine whether cell surface protein stem cell antigen-1 (Sca-1) plays a role in differentiation of stem cells into adipolineage.

2. Determine whether the localization and quantity of adipose-derived stem cells in fat tissues depends on obesity status of animals (high fat diet vs chow diet).

During the past year we characterized the immunophenotype of primary ear mesenchymal stem cells (EMSC). Flow cytometric analysis demonstrated that 80% of undifferentiated EMSC express Sca-1. Using magnetic cell sorting, we have enriched an EMSC population for Sca-1 positive cells (up to 98%). We show that Sca-1 enriched EMSC have greater potential to differentiate into adipocytes than Sca-1 depleted cells. It has been suggested that Sca-1 might be an important marker for somatic stem cells, since Sca-1 positive cells have a high potential for differentiation into cardiomyocytes and skeletal muscle. Additionally it has been shown that TZDs and high-fat feeding promote the trafficking of BM-derived Sca-1 positive circulating progenitor cells to adipose tissues and their differentiation into adipocytes. Whether Sca-1 positive cells are the source of adipocyte precursor cells is a major goal of our next in vivo study.