Effects of stimulators of protein kinases A and C and modulators of phosphorylation on plasminogen activator activity in porcine oocyte-cumulus cell complexes during in vitro maturation

✍ Scribed by Nam Hyung Kim; Alfred R. Menino Jr.

• Publisher: John Wiley and Sons
• Year: 1995
• Tongue: English
• Weight: 753 KB
• Volume: 40
• Category: Article
• ISSN: 1040-452X
• DOI: 10.1002/mrd.1080400313

✦ Synopsis

Abstract

Effects of phorbol myristate acetate (PMA), dibutyryl cyclic AMP (dbcAMP), 6‐dimethylami‐nopurine (6‐DMAP), and okadaic acid (OA) on plasminogen activator (PA) activity in porcine oocyte‐cumulus cell complexes (POCC) in vitro were determined. Cumulus cell‐enclosed oocytes were collected from 1–4 mm antral follicles and cultured in TCM‐199 with 0.3% polyvinyl‐pyrrolidone for 48 hr PA activities in POCC were quantified using SDS‐PAGE, casein‐agar zymography, and densitometry. Two plasminogen‐dependent lytic zones (93–96 kD and 71–79 kD) were observed in POCC. Addition of amilorde to the zymograph, a competitive inhibitor of urokinase‐type PA, failed to reduce activities in either zone, suggesting that the 71–79 kD band is a tissue‐type PA (tPA) and the 93–96 kD band is possibly a tPA‐inhibitor complex. Changes in PA activity due to the various treatments were expressed relative to the PA activity in 40 POCC. Increasing dbcAMP increased PA (P <0.05) activity in dose‐dependent fashion, whereas 6‐DMAP and 10 and 100ng/ml PMA inhibited (P <0.05) PA activity. PA activity increased (P <0.05) in POCC treated with up to 25 nM OA; however, activity decreased (P <0.05) at concentrations >75 nM. Treatment with 25 nM OA also induced the expression of an amiloride‐sensitive PA (49–52 kD). Germinal vesicle breakdown and progression to metaphase II were inhibited (P <0.05) by 2.5 mM dbcAMP and 2 mM 6‐DMAP, whereas 100 ng/ml PMA and 25 nM OA inhibited (P <0.05) only progression to metaphase II. These data suggest that PA production by POCC is influenced by protein kinases A and C and kinase inhibitors during oocyte maturation. Inhibition of intracellular phosphatases also induced novel PA production. © 1995 Wiley‐Liss, Inc.