The purpose of this administrative supplement is to accelerate progress of the parent R01 by defining the secretory phenotype of senescent preadipocytes using expression profiling approaches. This is based on new data since the parent grant was submitted and opportunities that have arisen due to my recent move to Mayo Clinic. By supplementing the grant, critical mechanisms underlying age-related pro-inflammatory changes in fat tissue and metabolic dysfunction will be delineated in greater depth and much faster. The hypothesis of the parent grant is that fat cell progenitor overutilization with aging generates senescent preadipocytes with a secretory phenotype that impairs adipogenesis. Its Aims are to: 1) test the hypothesis that dysfunctional preadipocytes accumulate with aging in humans, dissect responsible mechanisms, and test fat depot-dependence, 2) define the aging preadipocyte secretory phenotype, and 3) test if dysfunctional preadipocytes contribute to impaired adipogenesis with aging, define responsible mechanisms, and, based on these, devise molecular interventions. The Specific Aims of the Supplement are: Aim 1. To accelerate and strengthen Aims 1 and 2 of the parent grant by conducting array analyses of early, mid, and late passage human preadipocytes from different fat depots and confirm key gene changes and pathways in primary preadipocytes from subjects across the age spectrum. Primary cells needed to generate strains for these analyses have already been banked and no further human subjects beyond those in the parent protocol are needed. We have recently used C/MAP and other analytical approaches to delineate pathways responsible for differences demonstrated in expression arrays. These approaches will be used to define molecular mechanisms. Aim 2. To accelerate and strengthen Aims 2 and 3 of the parent grant by defining mechanisms through which senescent human preadipocytes disrupt function of neighboring fat cells using expression profiling approaches. In Aims 2 and 3 of the parent grant, the impact of senescent preadipocytes on co-cultured fat cells will be tested. To accelerate the proposed studies and define mechanisms, expression array analyses will be added to the analyses proposed in the parent grant. These experiments will greatly accelerate progress of the parent grant and will be completed within 2 years.