HYPERTROPHY OF RABBIT PROXIMAL TUBULE CELLS IS ASSOCIATED WITH OVEREXPRESSION OF TGF-BETA

The expression of transforming growth factor beta (TGF beta) in proxim al tubule cells from rabbit kidney cortex after uninephrectomy (UNX) w as investigated. Cell protein and [H-3]leucine incorporation in these cells were significantly increased, while cell number was decreased, a t two weeks following UNX. At this time period after UNX, we found tha t proximal tubule cells showed a dramatic increase of cytoplasmic immu nostaining with a pan-specific anti-TGF beta antibody. This was accomp anied by a 3-fold increase in TGF beta(1) mRNA expression in these cel ls. Furthermore, proximal tubule cells from two-week uninephrectomized rabbits secrete about 2-fold higher TGF beta bioactivity to the cell conditioned medium compared to cells from sham-operated animals Additi on of anti-TGF beta(1),beta(2),beta(3) neutralizing antibody increased the growth of the former cells, and it abolished cell hypertrophy The se results indicate that hypertrophy of proximal tubule cells during c ompensatory renal growth is associated with overexpression of TGF beta .