Valvular interstitial cells express angiotensinogen and cathepsin D, and generate angiotensin peptides

Laxmansa C. Katwa, Suresh C. Tyagi, Scott E. Campbell, Soon Jin Lee, George T. Cicila, Karl Weber

Research output: Contribution to journalArticle

48 Citations (Scopus)

Abstract

Cells capable of de novo angiotensin (Ang)II generation in the heart remain unidentified. High-density angiotensin converting enzyme (ACE) binding has been localized to sites of high collagen turnover, such as heart valve leaflets and their valvular interstitial cells (VIC). VIC express ACE mRNA and their membrane-bound ACE utilizes AngI as substrate. Whether VIC also express angiotensinogen (Ao) and an aspartyl protease, and whether they generate AngI and II de novo, is presently unknown. We sought to address these questions in serum-deprived cultured VIC. Ao, renin and cathepsin D (Cat-D) mRNA expression was addressed by RT-PCR. Production of Ao, AngI and AngII peptides were measured in VIC-culture media by radioimmunoassay (RIA). Immunoreactive Cat-D was detected by immunofluorescein labeling and Western blotting. Cat-D and renin activities were determined by spectrofluorometric and autoradiographic methods and AngI generation by RIA. Results showed (a) expression of Ao and Cat-D both at mRNA and protein levels; (b) AngI and AngII peptides in culture media; (c) acceleration of AngII production by exogenous AngI (1 nmol/l), which was blocked by lisinopril (0.1 μmol/l); (d) that dexamethasone (0.1 μmol/l) increased AngII production; (e) a 46 kDa immunoreactive Cat-D protein by Western blotting; (1) aspartyl protease activity, using chromogenic and 125I-labeled Ao as substrates, inhibited by pepstatin-A; and (g) the absence of renin mRNA and activity. It is concluded that at both the mRNA and protein levels, cultured VIC express Ao and Cat-D, and can generate AngI and AngII peptides by the action of a non-renin protease Cat-D and ACE, respectively. VIC therefore appear to represent a constitutive nonendothelial cell found in adult rat heart valve leaflets, which are capable of de novo Ang peptide generation.

Original languageEnglish (US)
Pages (from-to)807-821
Number of pages15
JournalInternational Journal of Biochemistry and Cell Biology
Volume28
Issue number7
DOIs
StatePublished - Jan 1 1996
Externally publishedYes

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Angiotensinogen
Cathepsin D
Angiotensins
Peptides
Peptidyl-Dipeptidase A
Messenger RNA
Renin
Aspartic Acid Proteases
Heart Valves
Culture Media
Radioimmunoassay
Chromogenics
Lisinopril
Western Blotting
Proteins
Substrates
Cell culture
Angiotensin II
Labeling
Dexamethasone

All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Cell Biology

Cite this

Valvular interstitial cells express angiotensinogen and cathepsin D, and generate angiotensin peptides. / Katwa, Laxmansa C.; Tyagi, Suresh C.; Campbell, Scott E.; Lee, Soon Jin; Cicila, George T.; Weber, Karl.

In: International Journal of Biochemistry and Cell Biology, Vol. 28, No. 7, 01.01.1996, p. 807-821.

Research output: Contribution to journalArticle

Katwa, Laxmansa C. ; Tyagi, Suresh C. ; Campbell, Scott E. ; Lee, Soon Jin ; Cicila, George T. ; Weber, Karl. / Valvular interstitial cells express angiotensinogen and cathepsin D, and generate angiotensin peptides. In: International Journal of Biochemistry and Cell Biology. 1996 ; Vol. 28, No. 7. pp. 807-821.
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