Linkage between phosphorylated cystatin alpha and filaggrin by epidermal transglutaminase as a model of cornified envelope and inhibition of cathepsin L activity by cornified envelope and the conjugated cystatin alpha.
Lysine-rich phosphorylated cystatin alpha (P-cystatin alpha) from newborn rat epidermis is a good substrate for epidermal transglutaminase (TGase) and also one of the component proteins of cornified envelope in the stratum corneum. Since the filaggrin linker segment peptide was efficiently conjugated with P-cystatin alpha and was mediated by epidermal TGase in the presence of Ca2+ ions, filaggrin is a candidate for the glutamine-rich linkage protein to conjugate with lysine-rich P-cystatin alpha. A conjugated protein was found by epidermal TGase in the activated condition with Ca2+ ions and dithiothreitol. In contrast, the conjugated protein was not formed under chelated conditions with EDTA. The conjugated protein reacted positively with anti-P-cystatin alpha polyclonal antibody (PoAb). The conjugated protein and purified cornified envelope showed an inhibitory effect against papain and cathepsin L, but cathepsin B and H were not inhibited by these P-cystatin alpha conjugates. Although the component protein, P-cystatin alpha itself, inhibited cathepsin H strongly, these conjugated proteins inhibited specifically the cathepsin L family. The amino acid composition of cornified envelope protein and the conjugated protein of P-cystatin alpha and filaggrin linker segment peptide was not completely the same. The conjugated protein of P-cystatin alpha and filaggrin linker segment peptide showed the same inhibitory properties against cysteine proteinases as the cornified envelope. These findings suggest that the linkage protein between P-cystatin alpha and filaggrin linker segment peptide may be considered a model of cornified envelope, although skin cornified envelope may be conjugated with some additional proteins.
Takahashi
M
M
Department of Dermatology, Kinky University School of Medicine, Osaka, Japan.
Tezuka
T
T
Kakegawa
H
H
Katunuma
N
N
D000595:Amino Acid Sequence; D000818:Animals; D056668:Cathepsin L; D002403:Cathepsins / Q000037:antagonists & inhibitors*; D015891:Cystatins / Q000378:metabolism*; D003546:Cysteine Endopeptidases; D010450:Endopeptidases; D000078404:Epidermal Cells; D004817:Epidermis / Q000201:enzymology*; D000091344:Filaggrin Proteins; D007381:Intermediate Filament Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D010766:Phosphorylation; D051381:Rats; D017207:Rats, Sprague-Dawley; D011503:Transglutaminases / Q000378:metabolism*
C070572:Csta protein, rat; D015891:Cystatins; D000091344:Filaggrin Proteins; D007381:Intermediate Filament Proteins; D011503:Transglutaminases; D002403:Cathepsins; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; D056668:Cathepsin L; C534280:Ctsl protein, rat