EXPRESSION OF TRANSFORMING GROWTH-FACTOR-BETA IN THE EMBRYONIC AVIAN LENS COINCIDES WITH THE PRESENCE OF MITOCHONDRIA

During their maturation, lens cells lose all membrane bound organelles , including mitochondria. In chicken embryos this process begins in th e central lens fibers beginning around embryonic day 12 (E12). Transfo rming growth factor beta (TGF beta) is a multipotent growth modulator thought to play a role in numerous developmental processes. TGF beta 1 has been localized to mitochondria in rat liver cells and muscle cell s. In the present study, we examined the expression of TGF beta isofor m mRNAs and proteins during chicken embryonic lens development. PCR an alysis demonstrated TGF beta 2 and TGF beta 3 transcripts in the lens epithelium and fibers throughout pre- and post-hatching development. T GF beta isoforms were detected throughout the lens epithelium and fibe rs early in development (E6). However by E19, the distribution of TGF beta 2 and TGF beta 3 transcripts and proteins coincided with regions of the lens that contained mitochondria. In addition, intense TGF beta staining was observed in the basal portions of the equatorial epithel ial cells, a region with abundant mitochondria. Transcripts for TGF be ta 1 and TGF beta 4 were not detected in any tissue or time frame exam ined. Similarly, no immunostaining for TGF beta 1 was observed. (C) 19 95 Wiley-Liss, Inc.