Human chorionic cells in primary culture: a model for renin biosynthesis

Area of Science:

• Reproductive biology
• Endocrinology
• Biochemistry

Background:

• Human fetal membranes, specifically amnion and chorion cells, are crucial for pregnancy.
• Renin, an enzyme in the renin-angiotensin system, plays a key role in blood pressure regulation.
• The cellular source and form of renin production in fetal membranes are not fully understood.

Purpose of the Study:

• To investigate renin secretion by human amnion and chorion cells.
• To characterize the properties of renin produced by chorionic cells.
• To determine if chorionic renin is secreted as an active or inactive form.

Main Methods:

• Culturing of human fetal membrane cells (amnion and chorion).
• Assay of renin secretion in culture supernatants.
• Activation of inactive renin using trypsin and acid dialysis.
• Comparison of antigenic and enzymatic properties with kidney renin.
• Metabolic labeling with [35S]methionine to determine molecular weight.

Main Results:

• Chorionic cells, but not amnionic cells, secrete renin.
• Chorionic renin is secreted as an inactive, high molecular weight (54K) form.
• This inactive form can be activated by trypsin or acid dialysis.
• Activated chorionic renin exhibits similar antigenic and enzymatic properties to kidney renin.

Conclusions:

• Human chorionic cells are a source of inactive renin.
• The secreted 54K inactive renin likely represents a proenzyme form.
• Chorionic renin shares characteristics with kidney renin, suggesting functional similarities.