Immunocytochemical Localization of Latent Transforming Growth Factor-B1 Activation by Stimulated Macrophages
Transforming growth factor-{beta}1 (TGF-{beta}) is secreted in a latent form consisting of mature TGF-{beta} noncovalently associated with its amino-terminal propeptide, which is called latency associated peptide (LAP). Biological activity depends upon the release of TGF-{beta} from the latent complex following extracellular activation, which appears to be the key regulatory mechanism controlling TGF-{beta} action. We have identified two events associated with latent TGF-{beta} (LTGF-{beta}) activation in vivo: increased immunoreactivity of certain antibodies that specifically detect TGF-{beta} concomitant with decreased immunoreactivity of antibodies to LAP. Macrophages stimulated in vitro with interferon-{gamma} and lipopolysaccharide reportedly activate LTGF-{beta} via cell membrane-bound protease activity. We show through dual immunostaining of paraformaldehyde-fixed macrophages that such physiological TGF-{beta} activation is accompanied by a loss of LAP immunoreactivity with concomitant revelation of TGF-{beta} epitopes. The induction of TGF-{beta} immunoreactivity colocalized with immunoreactive betaglycan/RIII in activated macrophages, suggesting that LTGF-{beta} activation occurs on the cell surface. Confocal microscopy of metabolically active macrophages incubated with antibodies to TGF-{beta} and betaglycan/RIII prior to fixation supported the localization of activation to the cell surface. The ability to specifically detect and localize LTGF-{beta} activation provides an important tool for studies of its regulation.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Director, Office of Energy Research; NASA Specialized Center of Research and Training in Radiation Health (US)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 773731
- Report Number(s):
- LBNL-42501; JCLLAX; TRN: AH200106%%133
- Journal Information:
- Journal of Cellular Physiology, Vol. 178, Issue 3; Other Information: PBD: 22 Sep 1998; ISSN 0021-9541
- Country of Publication:
- United States
- Language:
- English
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