Heat shock proteins (HSPs) can be induced by various stresses and play an important role in cell cycle progression. HSP70 has been shown to act as an inhibitor of apoptosis. We studied HSP70 expression in bronchial epithelial cells of C57BL/6 mice and homozygous HPS70 knockout mice (hsp70.1–/–) exposed to chronic hypoxic stress. We also investigated changes in cellular proliferation and apoptosis in relation to HSP70. Lungs were removed from mice after a three-week period of exposure to 10 % O2. Immunoblots for HSP70 and immunohistochemical staining for HSP70 and Ki-67 were performed. Apoptosis was assessed using the TUNEL assay. The three-week period of hypoxic stress did not change HSP70 levels in total lung tissue, but a significant reduction in HSP70 expression was observed in bronchiolar epithelial cells. In wild type mice, both HSP70 and Ki-67 expression were significantly reduced in bronchiolar epithelial cells. In homozygous HPS70 knockout mice (hsp70.1–/–), apoptosis of bronchiolar epithelial cells was significantly increased. Our results suggest that HSP70 may exert anti-apoptotic effects in mouse bronchiolar epithelial cells.
Severe xerostomia is a common late radiation consequence, which occurs after irradiation of head and neck malignancies. The aim of the present study was to analyze apoptosis and proliferation and their relationship during the late post-irradiation phase. C57BL/6 mice were locally irradiated in head and neck region with a single dose of 7.5 or 15 Gy and their submandibular glands were collected at 40 and 90 days after irradiation. To identify apoptotic cells, the TUNEL method was employed and immunohistochemistry with proliferating cell nuclear antigen (PCNA) was used for detecting proliferation. Histological changes at day 40 were mild in contrast to day 90 when glands of irradiated mice showed severe atrophy, vacuolization and mononuclear infiltration. Acinar cells, granular and intercalated duct cells of mice irradiated with 7.5 and 15 Gy expressed higher apoptotic index than cells of non-irradiated, control glands at both
examined time points. At 40 days, a higher proliferation index in granular and intercalated duct cells was detected only in group irradiated with 7.5 Gy. At 90 days, proliferation index for all cell types in both irradiated groups was similar to the controls. According to our results, the imbalance between apoptosis and proliferation caused by X-irradiation may be the reason for gland impairment during the late post-irradiation phase.
Abnormal proliferation of vascular smooth muscle cells (VSMCs) is known to be a key event in the development of atherosclerosis and restenosis. The present study examined the effect of a novel synthetic natriuretic peptide, vasonatrin peptide (VNP), on norepinephrine (NE)-induced proliferation of VSMCs from coronary bypass vessels. Human VSMCs were isolated from an internal mammary artery (IMA) and saphenous vein (SV) by explant culture and stimulated with NE. MTT assay and [3H] thymidine-incorporation were undertaken to analyze cell proliferation and radioimmunoassay was used to determine the level of intracellular cyclic 3’,5’-guanosine monophosphate (cyclic GMP). NE (10-8 - 10-7 mol/l) had a mitogenic effect in human VSMCs from both SV and IMA. However, NE-stimulated proliferation of VSMCs from SV was greater than that from IMA. Furthermore, low concentration of NE (10-10 mol/l) promoted cell growth in SV-derived cells but not in IMA-derived cells. VNP (10-8 - 10-6 mol/l) reduced NE-induced cell proliferation and increased intracellular cyclic GMP, which were abrogated by HS-142-1. In addition, the growth inhibition of VNP was mimicked by 8-bromo-cGMP. These results indicate that VNP has a significant inhibitory effect on NE-stimulated proliferation of human VSMCs from both IMA and SV, which is mediated by guanylate cyclase-linked receptors by increasing cyclic GMP.
The first trimester of pregnancy is characterized by continuous proliferation, invasion and differentiation of cytotrophoblasts. These processes are precisely controlled both, in space and time by molecules such as endothelin-1 (ET-1). ET-1 is expressed in human first trimester trophoblast and is known to stimulate cytotrophoblast proliferation through endothelin A and B receptor subtypes (ETA and ETB), and cytotrophoblast invasion through ETB. However, temporal changes of the ET system during the first trimester of pregnancy have not been previously studied. This study tested the hypothesis that ET-1 release, ETA and ETB expression are increased towards the end of the first trimester of pregnancy (weeks 10-12 vs. weeks 6-9), resulting in increased cytotrophoblast proliferation and invasion. Tissue samples were obtained from 17 surgical pregnancy interruptions (week 6-9: n=9; week 10-12: n=8). After cytotrophoblast isolation, the invasive and proliferative phenotypes were immune-separated by an α6-integrin antibody. Both proliferative and invasive cytotrophoblasts were cultured separately on plastic or Matrigel for 24 h. ET-1 release into the culture medium of both cytotrophoblast subtypes was measured by radioimmunoassay. ETA and ETB mRNA expression was measured by RT-PCR, and the ET-1 effect on cytotrophoblast proliferation and invasion was determined using proliferation and invasion assays, respectively. ET-1 release increased from early to late first trimester of pregnancy in both proliferative (1.8-4.5 fold) and invasive cytotrophoblasts (9.3-28 fold), especially when cultured on Matrigel. This was paralleled by less ETB mRNA on invasive cytotrophoblasts independent of the time period in first trimester, whereas ETA expression was similar on proliferative an invasive cytotrophoblasts. Proliferation and invasion of cytotrophoblasts under control conditions decreased from early to late first trimester. The ET-1/ET-receptor system changes between weeks 6-9 and 10-12 in pregnancy. Our data suggest an autocrine and endocrine ET-1 effect, which is stronger in late than in early first trimester of pregnancy paralleled by different stimulatory effects on trophoblast invasion and proliferation. In general, this suggests time as an additional effector of the critical processes governing placental development in the first trimester of human pregnancy., A. Majali-Martinez, S. Barth, U. Lang, G. Desoye, M. Cervar-Zivkovic., and Seznam literatury
Developmental dysplasia and dislocation of the hip (DDH) is the
most common type of lower limb deformity in pediatric
orthopedics. The mechanism of the signaling pathway has been
studied in depth. However, the role of epigenetic regulation, such
as lncRNA, is still far from clear. In this study, we successfully
established a rat model of DDH and demonstrated that H19 was
down-regulated in the development of DDH. Further, we
constructed H19 knockdown (KD) and overexpression
chondrocytes. H19 KD suppressed the proliferation of normal
chondrocytes, while overexpression of H19 promoted cell
proliferation of DDH chondrocytes. Finally, we revealed that H19
bound to let-7 and inhibited its function, acting as a competing
endogenous RNA. Down-regulation of H19 is closely associated
with DDH progression and H19 is an important epigenetic factor
that regulates the proliferation of chondrocytes. H19 may thus be
a potential clinical marker for DDH diagnosis and treatment.