Expression of non-muscle myosin isoforms in rabbit myometrium is estrogen-dependent.
The putatative effects of different estrogen levels on the expression of non-muscle myosin isoforms in rabbit myometrium have been investigated using three monoclonal anti-platelet myosin heavy chain (MyHC) antibodies (NM-F6, NM-G2, and NM-A9). Western blotting analysis of proteolytic digests of human platelet actomyosin indicates that these antibodies are specific for three distinct epitopes. Comparative immunofluorescence tests on cultered human fibroblasts with polyclonal sequence-specific anti-MyHCA antibody suggest that the patterns of NM-F6, NM-.G2 and NM-A9, although similar, do not overlap with that of type-A MyHC. Distribution of NM myosin isoforms has been studied in indirect immunofluorescence assays using cryosections of tissues from rabbits at various stages of development, pregnancy, or from ovariectomized, 17beta-estradiol-treated ovariectomized, and human chorionic gonadotropin-treated animals. Non-muscle myosin antigenicity is still present in the myometrium when the female becomes sexually competent. The immunoreactivity of non-muscle myosin for NM-F6 is steroid-independent, since it does not change with pregnancy or ovariectomy, but that of NM-G2 is estrogen-dependent; the latter disappears during pregnancy and in ovariectomized animals treated with estradiol, whereas it is expressed in ovariectomized rabbits. Although non-muscle myosin immunoreactivity for NM-A9 is detectable under all the experimental conditions, it can assume different patterns of intracellular distribution in vitro (punctate vs filamentous), depending on culture conditions and the presence of estrogens.
Chiavegato
A
A
Department of Biomedical Sciences, University of Padua, Padua, Italy.
Capriani
A
A
Azzarello
G
G
Vinante
O
O
Pauletto
P
P
Sartore
S
S
D000818:Animals; D000911:Antibodies, Monoclonal; D000918:Antibody Specificity; D015153:Blotting, Western; D002454:Cell Differentiation / Q000502:physiology; D002478:Cells, Cultured; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D018604:Epitope Mapping; D004967:Estrogens / Q000502:physiology*; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D007150:Immunohistochemistry; D007536:Isomerism; D009130:Muscle, Smooth / Q000166:cytology / Q000378:metabolism; D009215:Myometrium / Q000378:metabolism* / Q000502:physiology; D009218:Myosins / Q000096:biosynthesis* / Q000276:immunology; D010052:Ovariectomy; D011247:Pregnancy; D011817:Rabbits
D000911:Antibodies, Monoclonal; D006063:Chorionic Gonadotropin; D004967:Estrogens; D009218:Myosins