Lysosomal function in the degradation of defective collagen in cultured lung fibroblasts. Academic Article uri icon

Overview

MeSH

  • Cells, Cultured
  • Endopeptidases
  • Female
  • Fibroblasts
  • Humans
  • Leupeptins
  • Pepstatins
  • Pregnancy
  • Procollagen
  • Tosyllysine Chloromethyl Ketone

MeSH Major

  • Collagen
  • Lung
  • Lysosomes

abstract

  • Human fibroblasts when induced to make nonhelical , defective collagen have mechanisms for degrading up to 30% of their newly synthesized collagen intracellularly prior to secretion. To determine if at least a portion of the degradation of defective collagen occurs by lysosomes, extracts of cultured HFL-1 fibroblasts were examined for proteinases capable of degrading denatured type I [3H]procollagen. The majority of the proteolytic activity against denatured [3H]-procollagen had a pH optimum of 3.5-4; it was stimulated by dithiothreitol and inhibited 95% by leupeptin, 10% by pepstatin, and 98% by leupeptin and pepstatin together. Extracts of purified lysosomes from the fibroblasts were active in degrading denatured [3H]procollagen and were completely inhibited by leupeptin and pepstatin. To demonstrate directly that human lung fibroblasts can translocate a portion of their defective collagen to lysosomes, cultured cells were incubated with cis-4-hydroxyproline and labeled with [14C]proline to cause the cells to make nonhelical [14C]procollagen. About 3% of the total intracellular hydroxy[14C]proline was found in lysosomes. If, however, the cells were also treated with NH4Cl, an inhibitor of lysosomal function, 18% of the intracellular hydroxy[14C]proline was found in lysosomes. These results demonstrate that cultured human lung fibroblasts induced to make defective collagen are capable of shunting a portion of such collagen to their lysosomes for intracellular degradation.

publication date

  • May 8, 1984

has subject area

  • Cells, Cultured
  • Collagen
  • Endopeptidases
  • Female
  • Fibroblasts
  • Humans
  • Leupeptins
  • Lung
  • Lysosomes
  • Pepstatins
  • Pregnancy
  • Procollagen
  • Tosyllysine Chloromethyl Ketone

Research

keywords

  • Journal Article

Identity

Language

  • eng

PubMed ID

  • 6375717

Additional Document Info

start page

  • 2134

end page

  • 2138

volume

  • 23

number

  • 10