Objective :The Hutchinson-Gilford progeria syndrome (HGPS or progeria) is a childhood disorder with features of premature aging and is caused by mutations in the lamin A gene resulting in the production of an abnormal protein, termed progerin. To investigate the underlying pathogenic mecha-nism, we studied the nuclear co-localization and association of progerin interactive partner proteins (PIPPs) with lamina proteins. Methods:Both wild-type (WT) and progeria fibroblasts were studied by various methods including eonfocal microscopy, immunopreeipitation and Western blot. Results:All PIPPs discovered so-far co-localized with lamin A/C. In addition, the PIPPs were selectively associated with lamina proteins. An increased immunofluorescent staining signal was found for Mel18 in HGPS as com-pared to WT cells. An association of Me118 with emerin was observed in HGPS, but not in WT cells.Conclusion: Based on these findings, we propose that PIPPs, along with associated lamina proteins may form a pathogenic progerin-containing protein complex.rn