Expression and regulation of HSPB5 in the myometrium throughout pregnancy
Date
2015-10-21
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
Type
Thesis
Degree Level
Masters
Abstract
The uterine smooth muscle or myometrium goes through phases of differentiation
during pregnancy to become a powerful contractile tissue at term. Small Heat Shock proteins
(sHSPs) are a family of ten small molecular weight proteins in mammals that are induced by
many physiological stressors such as uterine stretch. Some sHSPs act as chaperones, but also
others assist in cell death regulation, cytoskeleton rearrangements, and immune system
activation. We examined the spatio-temporal expression of HSPB5 protein throughout
gestation via immunoblot and immunofluorescence analysis, as well as the effect of uterine
distension on myometrial HSPB5 protein expression using unilaterally pregnant rat models.
HSPB5 protein expression significantly increased on day (d) 17 (p<0.05; vs all other timepoints)
and levels steadily decreased thereafter through to postpartum (PP). In contrast, serine-59
phosphorylated (pSer59) HSPB5 protein detection was significantly increased from d19 through
to PP (p<0.05). Both HSPB5 and pSer59-HSPB5 were detected in the cytoplasm of myocytes
within both uterine muscle layers mid- to late-pregnancy. In unilaterally pregnant rats, HSPB5
protein and pSer59-HSPB5 protein expression were significantly elevated in gravid uterine
horns at both d19 of gestation and d23 (labour) compared to non-gravid horns. The spatial
expression of total and pSer59-HSPB5 protein in a human myometrial cell line was examined by
immunofluorescence analysis. Total HSPB5 co-localized with α-smooth muscle actin and
pSer59-HSPB5 was co-localized with the focal adhesion protein kindlin-2 (KIN-2) and the
exosomal marker CD63. Therefore, HSPB5 is highly expressed during mid- to late-pregnancy
and expression appears to be regulated by uterine distension. HSPB5 may be involved in
regulating actin filament dynamics and could be secreted by exosomes.
Description
Keywords
HSPB5, stress proteins, pregnancy, myometrium, uterus, labour, actin, kindlin-2, CD63
Citation
Degree
Master of Science (M.Sc.)
Department
Veterinary Biomedical Sciences
Program
Veterinary Biomedical Sciences