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1.
Effects of TGF-betas and a specific antagonist on apoptosis of immature rat male germ cells in vitro 总被引:1,自引:0,他引:1
Konrad L Keilani MM Laible L Nottelmann U Hofmann R 《Apoptosis : an international journal on programmed cell death》2006,11(5):739-748
Massive apoptosis of pubertal male germ cells is important for the development of functional spermatogenesis in the adult
testis. Although the trigger(s) for male germ cell loss at puberty remain undefined, we have hypothesized that transforming
growth factor-betas (TGF-βs) play an active role. Here we demonstrate that the three mammalian TGF-β isoforms, TGF-β1, TGF-β2
and TGF-β3, induce distinct apoptosis of pubertal spermatogonia and spermatocytes in a dose-dependent manner. Induction of
male germ cell death by activation of caspase-3 was most pronounced with TGF-β2 compared to TGF-β1 and TGF-β3. Furthermore,
we found colocalization of activated caspase-3 with apoptotic protease-activating factor-1 (Apaf-1) in apoptotic germ cells,
thus indicating the importance of the intrinsic mitochondrial pathway in TGF-β-induced apoptosis. The specificity of the TGF-β
effects was proven by addition of recombinant latency-associated peptide against TGF-β1 (rLAP-TGF-β1) which completely abolished
TGF-β1-induced and TGF-β3-induced germ cell apoptosis. Although TGF-β2-triggered germ cell death also was significantly reduced
by rLAP-TGF-β1, inhibition was not maximal. Our results suggest that the three TGF-β isoforms induce apoptosis of pubertal
male germ cells via the mitochondrial pathway in vitro and are thus likely candidates involved in the excessive first wave of apoptosis of male germ cells during puberty.
Lutz Konrad and Marcel Munir Keilani contributed equally to this work. 相似文献
2.
NAG-1 up-regulation mediated by EGR-1 and p53 is critical for quercetin-induced apoptosis in HCT116 colon carcinoma cells 总被引:4,自引:0,他引:4
Lim JH Park JW Min DS Chang JS Lee YH Park YB Choi KS Kwon TK 《Apoptosis : an international journal on programmed cell death》2007,12(2):411-421
Quercetin, a flavonoid molecule ubiquitously present in nature, has multiple effects on cancer cells, including the inhibition
of cell proliferation and migration. However, the responsible molecular mechanisms are not fully understood. We found that
quercetin induces the expression of NAG-1 (Non-steroidal anti-inflammatory drug activated gene-1), a TGF-β superfamily protein,
during quercetin-induced apoptosis of HCT116 human colon carcinoma cells. Reporter assays using the luciferase constructs
containing NAG-1 promoter region demonstrate that early growth response-1 (EGR-1) and p53 are required for quercetin-mediated
activation of the NAG-1 promoter. Overexpression of NAG-1 enhanced the apoptotic effect of quercetin, but suppression of quercetin-induced
NAG-1 expression by NAG-1 siRNA attenuated quercetin-induced apoptosis in HCT116 cells. Taken together, the present study
demonstrates for the first time that quercetin induces apoptosis via NAG-1, providing a mechanistic basis for the apoptotic
effect of quercetin in colon carcinoma cells. 相似文献
3.
The in vitro occurrence of apoptosis in hepatic cells has not been well characterized because it depends on apoptosis inducing-agents
and culture conditions. Furthermore, for a given hepatic cell and the same agent, discrepant results have been reported depending
on the technique used to evaluate the proportion of apoptotic cells. In this study, we compared the effects of several apoptosis-inducing
agents – transforming growth factor β1 (TGF-β1), retinoic acid (RA), okadaic acid (OA), and cycloheximide (CY) – on two types of hepatic cells, the human hepatoma cell
line Hep3B and normal rat hepatocytes, maintained either plated for 24 to 48 h or in suspension for 20 h. Chromatin condensation
and/or nucleus fragmentation were investigated morphologically by DAPI staining. DNA fragmentation was investigated biochemically
by agarose gel electrophoresis and poly(ADP-ribose) polymerase (PARP) cleavage was studied by western blot. Apoptotic cells
were quantified either by counting cells on UV microscopy after DAPI staining or by flow cytometry. Nuclear changes, the ladder
pattern on DNA electrophoresis and PARP cleavage were observed in plated cells, hepatoma cells and normal rat hepatocytes,
with all inducers but especially with OA. Semiquantification confirmed that OA was a strong inducer in plated cells under
the present conditions, since about 14% and 30% of Hep3B cells (with DAPI staining and flow cytometry, respectively) were
apoptotic after 48 h treatment, while, with the other inducers, apoptosis was weaker and discrepancies were also observed
between the two counting methods (TGF-β1; 4% and 12%; RA, 7% and 12%; CY, 4% and 16%, with DAPI staining and flow cytometry, respectively). OA induced a moderate
apoptosis in cultured hepatocytes (13% with DAPI staining), while TGF-β1, RA and CY were found to be weakly apoptotic (respectively 4% for the first two and 6% for the last ) after 48 h. In contrast,
in suspension cells, apoptosis was observed neither in Hep3B cells nor in normal hepatocytes, whatever the apoptotic inducer
and whatever the techniques used to detect apoptosis. In conclusion, our results show that induction of apoptosis in hepatic
cells depends not only on the apoptosis-inducing agent but also on the culture conditions.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
4.
Activation of extracellular signal-regulated kinase by TGF-β1 via TβRII and Smad7 dependent mechanisms in human bronchial epithelial BEP2D cells 总被引:1,自引:0,他引:1
Huo YY Hu YC He XR Wang Y Song BQ Zhou PK Zhu MX Li G Wu DC 《Cell biology and toxicology》2007,23(2):113-128
Transforming growth factor-β1 (TGF-β1) can activate mitogen-activated protein kinases (MAPKs) in many types of cells. The
mechanism of this activation is not well elucidated. Here, we explore the role of TGF-β/Smads signaling compounds in TGF-β1-mediated
activation of extracellular signal-regulated kinase (ERK) MAPK in human papillomavirus (HPV)-18 immortalized human bronchial
epithelial cell line BEP2D and the role of TGF-β1-induced phosphorylation of ERK in proliferation and apoptosis of BEP2D.
The cell models of siRNA-mediated silencing of TGF-β receptor type II (TβRII), Smad2, Smad3, Smad4, and Smad7 were employed
in this study. Our results demonstrate that TGF-β1 activates ERK in a time-dependent manner with a maximum effect at 60 min;
overexpression of Smad7 increased this TGF-β1-mediated phosphorylation of the ERK; and siRNA-mediated silencing of TβRII,
Smad3, Smad4, and Smad7 abrogated this effect. Moreover, we observed that overexpression of Smad7 restored TGF-β1-mediated
ERK phosphorylation in Smad4 knockdown cells but not in TβRII knockdown cells. In BEP2D cells, TGF-β1 treatment effectively
inhibited cells’ proliferation and induced their apoptosis. Pretreatment with U0126, an inhibitor of ERK1/2, significantly
enhanced the TGF-β1-mediated antiproliferative and apoptosis induction effects in BEP2D cells. These data revealed that TβRII
and Smad7 play the critical roles in TGF-β1-mediated activation of ERK; Smad3 and Smad4 can play an indirect role through
up-regulating Smad7 expression; and TGF-β1-induced phosphorylation of ERK may participate in BEP2D cell proliferation and
apoptosis regulation. 相似文献
5.
Huang EJ Wu CC Lee SD Chen JH Liu JY Ko JL Lin JA Lu MC Chen LM Huang CY Kuo WW 《Molecular and cellular biochemistry》2006,287(1-2):137-145
Hepatocellular carcinoma (HCC), the major manifestation of primary liver cancer, is one of the most frequent and malignant cancers worldwide, especially in Taiwan. Estrogen receptors (ERs) have been reported to play either a proliferation- or apoptosis-enhancing role in the differentiation of cancers, including HCC. In a previous experiment, we showed that transient overexpressed estrogen receptor-α induced early stage HCC cell line Hep 3B cell apoptosis by increasing the hTNF-α gene expression in a ligand-independent manner. To further clarify if the apoptotic effect occurs in poorly differentiated HCC cell line, HA22T, and elucidate the roles of ERs and TNF-α, DNA fragmentation and caspase activity were measured in late stage HCC cell line, HA22T, by measuring the expression of hER-α and hER-β using a Tetracycline-induciable system (Tet-on). Increased DNA fragmentation and caspase-3 activity were found in hERβ-overexpressed HA22T cells treated with estrogen (10−8 M) but not in hERα-overexpressed HA22T cells. Using RT-PCR/PCR and western blotting in HA22T cells, overexpressed hER-β was also found to increase the expression of hTNF-α mRNA and induce hTNF-α-dependent luciferase activity in a ligand-dependent manner. Additionally, LPS treatment and hER-β overexpression both enhance caspase-8 activities, whereas neither hER-β nor E2 treatment affected caspase-9 activities. In addition, the overexpressed hER-β plus E2 enhanced DNA fragmentation and caspase-8 activities were only partially reduced by anti-hTNF-α (0.1ng/ml), which was possibly due to the involvement of P53 and TGF-β. Taken together, our data indicates that overexpressed hER-β but not hER-α may induce caspase-8-mediated apoptosis by increasing the hTNF-α gene expression in a ligand-dependent manner in poorly differentiated HA22T cells. (Mol Cell Biochem xxx: 1–9, 2005)Shares equally contribution Contract grant sponsor: National Science Council; Contract grant number: NSC 91-2314-B-075A-006, NSC 92-2314-B-075A-014. 相似文献
6.
7.
Zhiguo Zhang Lin Wu Julei Wang Gang Li Dayun Feng Bin Zhang Lihong Li Jiandong Yang Lianting Ma Huaizhou Qin 《PloS one》2014,9(4)
Nonsteroidal anti-inflammatory drug (NSAID) activated gene-1 (NAG-1) is a divergent member of the transforming growth factor-beta (TGF-β) superfamily. NAG-1 plays remarkable multifunctional roles in controlling diverse physiological and pathological processes including cancer. Like other TGF-β family members, NAG-1 can play dual roles during cancer development and progression by negatively or positively modulating cancer cell behaviors. In glioblastoma brain tumors, NAG-1 appears to act as a tumor suppressor gene; however, the precise underlying mechanisms have not been well elucidated. In the present study, we discovered that overexpression of NAG-1 induced apoptosis in U87 MG, U118 MG, U251 MG, and T98G cell lines via the intrinsic mitochondrial pathway, but not in A172 and LN-229 cell lines. NAG-1 could induce the phosphorylation of PI3K/Akt and Smad2/3 in all six tested glioblastoma cell lines, except Smad3 phosphorylation in A172 and LN-229 cell lines. In fact, Smad3 expression and its phosphorylation were almost undetectable in A172 and LN-229 cells. The PI3K inhibitors promoted NAG-1-induced glioblastoma cell apoptosis, while siRNAs to Smad2 and Smad3 decreased the apoptosis rate. NAG-1 also stimulated the direct interaction between Akt and Smad3 in glioblastoma cells. Elevating the level of Smad3 restored the sensitivity to NAG-1-induced apoptosis in A172 and LN-229 cells. In conclusion, our results suggest that PI3K/Akt and Smad-dependent signaling pathways display opposing effects in NAG-1-induced glioblastoma cell apoptosis. 相似文献
8.
Liagre B Vergne-Salle P Corbiere C Charissoux JL Beneytout JL 《Arthritis research & therapy》2004,6(4):R373-R383
In the present study, we have shown for the first time that a plant steroid, diosgenin, causes an inhibition of the growth
of fibroblast-like synoviocytes from human rheumatoid arthritis, with apoptosis induction associated with cyclooxygenase-2
(COX-2) up-regulation. Celecoxib, a selective COX-2 inhibitor, provoked a large decrease in diosgenin-induced apoptosis even
in the presence of exogenous prostaglandin E2, whereas interleukin-1β, a COX-2 inducer, strongly increased diosgenin-induced apoptosis of these synoviocytes. These findings
suggest that the proapoptotic effect of diosgenin is associated with overexpression of COX-2 correlated with overproduction
of endogenous prostaglandin E2. We also observed a loss of mitochondrial membrane potential, caspase-3 activation, and DNA fragmentation after diosgenin
treatment. 相似文献
9.