Effects Of Leukemia Inhibitory Factor Research Articles

Augmentative effects of leukemia inhibitory factor reveal a critical role for TYK2 signaling in vascular calcification

Medial vascular calcification in chronic kidney disease (CKD) involves pro-inflammatory pathways induced by hyperphosphatemia. Several interleukin 6 family members have been associated with pro-calcific effects in vascular smooth muscle cells (VSMCs) and are considered as therapeutic targets. Therefore, we investigated the role of leukemia inhibitory factor (LIF) during VSMC calcification. LIF expression was found to be increased following phosphate exposure of VSMCs. LIF supplementation aggravated, while silencing of endogenous LIF or LIF receptor (LIFR) ameliorated the pro-calcific effects of phosphate in VSMCs. The soluble LIFR mediated antagonistic effects towards LIF and reduced VSMC calcification. Mechanistically, LIF induced phosphorylation of the non-receptor tyrosine-protein kinase 2 (TYK2) and signal transducer and activator of transcription-3 (STAT3) in VSMCs. TYK2 inhibition by deucravacitinib, a selective, allosteric oral immunosuppressant used in psoriasis treatment, not only blunted the effects of LIF, but also interfered with the pro-calcific effects induced by phosphate. Conversely, TYK2 overexpression aggravated VSMC calcification. Ex vivo calcification of mouse aortic rings was ameliorated by Tyk2 pharmacological inhibition and genetic deficiency. Cholecalciferol-induced vascular calcification in mice was improved by Tyk2 inhibition and in the Tyk2-deficient mice. Similarly, calcification was ameliorated in Abcc6/Tyk2-deficient mice after adenine/high phosphorus-induced CKD. Thus, our observations indicate a role for LIF in CKD-associated vascular calcification. Hence, the effects of LIF identify a central pro-calcific role of TYK2 signaling, which may be a future target to reduce the burden of vascular calcification in CKD.

Protective effect of leukemia inhibitory factor on the retinal injury induced by acute ocular hypertension in rats.

Glaucoma is one of the leading causes of irreversible blindness worldwide. As such, neuroprotective therapy is essential for the treatment of this disease. Leukemia inhibitory factor (LIF) is a member of the IL-6 cytokine family and the LIF signaling pathway is considered to be one of the major endogenous factors mediating neuroprotection in the retina. Therefore, the present study aimed to investigate the possible effects of LIF in acute ocular hypertension (AOH). The intraocular pressure in rat eyes was raised to 110 mmHg for 1 h by infusing the anterior chamber with normal saline to establish the AOH model. In the treatment group, LIF was then injected into the vitreous cavity after AOH was ceased. The retinal tissues were obtained after the termination of AOH, and H&E staining was conducted to assess the morphological damage. The number of retinal ganglion cells (RGCs) was counted using the Fluoro-Gold retrograde staining method. TUNEL staining was used to determine the extent of apoptosis among the retinal cells. In addition, the protein expression levels of cleaved caspase-3, poly (ADP-ribose) polymerase (PARP), STAT3 and components of the AKT/mTOR/70-kDa ribosomal protein S6 kinase (p70S6K) signaling pathway were examined by western blotting. The results showed that AOH induced tissue swelling and structural damage in the retina, which were reversed by LIF injection. In the LIF treatment group, RGC loss was significantly inhibited and the quantity of TUNEL-stained cells was also significantly reduced, whereas the expression of cleaved caspase-3 and PARP was decreased. Furthermore, increased phosphorylation of STAT3, AKT, mTOR and p70S6K was observed after LIF treatment. By contrast, pretreatment with the STAT3 inhibitor C188-9 or the PI3K/AKT/mTOR inhibitor LY3023414 reversed the LIF-induced inhibition of RGC loss. These results suggested that exogenous LIF treatment inhibited the retinal damage induced by AOH, which was associated with the activation of STAT3 and mTOR/p70S6K signaling. Therefore, LIF may serve a role in neuroprotection for glaucoma treatment.

Investigation into the effects of leukemia inhibitory factor on the bone repair capacity of BMSCs-loaded BCP scaffolds in the mouse calvarial bone defect model.

Leukemia inhibitory factor (LIF) is known to play a major role in bone physiology. In the present study, we examined the in vitro effects of LIF on osteoblast differentiation of bone marrow stem cells (BMSCs) and explored in vivo effects of LIF on the bone repair capacity of BMSCs-loaded biphasic calcium phosphate (BCP) scaffolds in mouse calvarial bone defect model. The mRNA and protein expression levels in the BMSCs were determined by quantitative real-time PCR and western blot, respectively; the in vitro osteoblast differentiation of the BMSCs was evaluated by using Alizarin Red S staining. The bone volume and bone density in the repaired calvarial bone defect were determined by Micro-CT. Bone regeneration was also histologically evaluated by hematoxylin and eosin staining and Masson's trichrome staining. Hypoxia treatment induced the up-regulation of Lif mRNA and LIF protein in the BMSCs. Lif overexpression up-regulated the mRNA expression levels of osteopontin and Runt-related transcription factor 2, and increased intensity of Alizarin Red S staining in the BMSCs; while Lif silence exerted the opposite effects. The in vivo studies showed that implantation of Lif-overexpressing BMSCs-loaded BCP scaffolds significantly increased the bone volume and bone density at 4 and 8weeks after transplantation, and promoted the regeneration of bone tissues in the mouse calvarial bone defect at 8weeks after transplantation when compared to the BMSCs-loaded BCP scaffolds group; while Lif-silencing BMSCs-loaded BCP scaffolds had the opposite effects. The present study for the first time demonstrated that LIF promoted the in vitro osteoblast differentiation of hypoxia-treated BMSCs; and further studies revealed that LIF exerted enhanced effects on the bone repair capacity of BMSCs-load BCP scaffolds in mouse calvarial bone defect model. However, future studies are warranted to determine the detailed mechanisms of LIF in the large-scale bone defect repair.

Prognostic value of leukemia inhibitory factor and its receptor in pancreatic adenocarcinoma.

Currently, the prognostic effects of leukemia inhibitory factor (LIF) and LIF receptor (LIFR) in pancreatic adenocarcinoma (PAAD) are not clear. In the present study, we utilized the large datasets from four public databases to investigate the expression of LIF and LIFR and their clinical significance in PAAD. Eight cohorts containing 1278 cases with PAAD were identified and the analysis results suggested that LIF was highly expressed while LIFR was lowly expressed in PAAD tissues compared with adjacent or normal tissues. Kaplan-Meier plot curves and univariate and multivariate Cox proportional hazards regression analyses indicated high LIF expression was associated with shorter overall survival (adjusted hazard ratio=1.641, 95% CI: 1.399-1.925, p < 0.001) whereas high LIFR expression was associated with longer overall survival (adjusted hazard ratio=0.653, 95% CI: 0.517-0.826, p < 0.001).

LIF, a Novel Myokine, Protects Against Amyloid-Beta-Induced Neurotoxicity via Akt-Mediated Autophagy Signaling in Hippocampal Cells

BackgroundLeukemia inhibitory factor, a novel myokine, is known to be associated with neural function, but the underlying molecular mechanism remains unclear.MethodsHT-22 mouse hippocampal cells, primary hippocampal cells, and Drosophila Alzheimer’s disease model were used to determine the effect of leukemia inhibitory factor on neurons. Immunoblot analysis and immunofluorescence method were used to analyze biological mechanism.ResultsLeukemia inhibitory factor increased Akt phosphorylation in a phosphoinositide-3-kinase-dependent manner in hippocampal cells. Leukemia inhibitory factor also increased the phosphorylation of the mammalian target of rapamycin and the downstream S6K. Leukemia inhibitory factor stimulated the phosphorylation of signal transducer and activator of transcription via extracellular signal-regulated kinases. Leukemia inhibitory factor increased c-fos expression through both Akt and extracellular signal-regulated kinases. Leukemia inhibitory factor blocked amyloid β-induced neural viability suppression and inhibited amyloid β-induced glucose uptake impairment through the block of amyloid β-mediated insulin receptor downregulation. Leukemia inhibitory factor blocked amyloid β-mediated induction of the autophagy marker, microtubule-associated protein 1A/1B-light chain 3. Additionally, in primary prepared hippocampal cells, leukemia inhibitory factor stimulated Akt and extracellular signal-regulated kinase, demonstrating that leukemia inhibitory factor has physiological relevance in vivo. Suppression of the autophagy marker, light chain 3II, by leukemia inhibitory factor was observed in a Drosophila model of Alzheimer’s disease.ConclusionsThese results demonstrate that leukemia inhibitory factor protects against amyloid β-induced neurotoxicity via Akt/extracellular signal-regulated kinase-mediated c-fos induction, and thus suggest that leukemia inhibitory factor is a potential drug for Alzheimer’s disease.

Expression and effects of leukemia inhibitory factor on nucleus pulposus degeneration.

Leukemia inhibitory factor (LIF) is a multifunctional cytokine. The present study aimed to determine the expression and effects of LIF on nucleus pulposus generation. Degenerated nucleus pulposus samples were obtained from animal models and patients with lumbar intervertebral disc herniation. Degradation scores of intervertebral discs were evaluated via magnetic resonance imaging (MRI) and histology, and the protein expression levels of LIF were detected. Furthermore, cultured primary human degenerated nucleus pulposus cells (DNPCs) were stimulated with various concentrations of recombinant human LIF protein (rhLIF), and aggrecan and collagen type II α1 (COL2α1) protein expression levels were detected by western blotting. In addition, aggrecan expression was determined by toluidine blue staining. The effects of rhLIF on proliferation and apoptosis of DNPCs were evaluated by Cell Counting Kit-8 and flow cytometry, respectively. The results revealed that the degradation scores of intervertebral discs were significantly associated with modeling time, as determined by MRI and histology. In addition, the protein expression levels of LIF were initially increased in patients with lumbar disc herniation and in rabbit models, particularly in the 2-week modeling group; however, its expression decreased with the progression of disc degeneration. Notably, LIF expression in each modeling group was higher than that in the control and 0 week modeling group. The in vitro study revealed that the protein expression levels of aggrecan and COL2α1 were significantly increased in response to rhLIF, in a dose-dependent manner, and statistical differences were identified between the treatment groups and control group. The results of toluidine blue staining were consistent with this finding. Although rhLIF had no effect on proliferation, it inhibited apoptosis of DNPCs in a concentration-dependent manner. In conclusion, LIF was upregulated during the process of intervertebral disc degeneration, and may promote the expression of extracellular matrix components. It may also be hypothesized that LIF acts as a potential protective factor by inhibiting apoptosis of DNPCs without affecting cell proliferation.

Leukemia inhibitory factor inhibits erythropoietin-induced myelin gene expression in oligodendrocytes

BackgroundThe pro-myelinating effects of leukemia inhibitory factor (LIF) and other cytokines of the gp130 family, including oncostatin M (OSM) and ciliary neurotrophic factor (CNTF), have long been known, but controversial results have also been reported. We recently overexpressed erythropoietin receptor (EPOR) in rat central glia-4 (CG4) oligodendrocyte progenitor cells (OPCs) to study the mechanisms mediating the pro-myelinating effects of erythropoietin (EPO). In this study, we investigated the effect of co-treatment with EPO and LIF.MethodsGene expression in undifferentiated and differentiating CG4 cells in response to EPO and LIF was analysed by DNA microarrays and by RT-qPCR. Experiments were performed in biological replicates of N ≥ 4. Functional annotation and biological term enrichment was performed using DAVID (Database for Annotation, Visualization and Integrated Discovery). The gene-gene interaction network was visualised using STRING (Search Tool for the Retrieval of Interacting Genes).ResultsIn CG4 cells treated with 10 ng/ml of EPO and 10 ng/ml of LIF, EPO-induced myelin oligodendrocyte glycoprotein (MOG) expression, measured at day 3 of differentiation, was inhibited ≥4-fold (N = 5, P < 0.001). Inhibition of EPO-induced MOG was also observed with OSM and CNTF. Analysis of the gene expression profile of CG4 differentiating cells treated for 20 h with EPO and LIF revealed LIF inhibition of EPO-induced genes involved in lipid transport and metabolism, previously identified as positive regulators of myelination in this system. In addition, among the genes induced by LIF, and not by differentiation or by EPO, the role of suppressor of cytokine signaling 3 (SOCS3) and toll like receptor 2 (TLR2) as negative regulators of myelination was further explored. LIF-induced SOCS3 was associated with MOG inhibition; Pam3, an agonist of TLR2, inhibited EPO-induced MOG expression, suggesting that TLR2 is functional and its activation decreases myelination.ConclusionsCytokines of the gp130 family may have negative effects on myelination, depending on the cytokine environment.

Protective effect of leukemia inhibitory factor on light induced retinal photoreceptors damage and its mechanisms

Objective To investigate the role of leukemia inhibitory factor (LIF) on retinal photoreceptor cells and the underlying mechanism after light damage. Methods Fifty 5-6 weeks old BALB/c mice were randomly divided into normal control group (10 mice), light damage+ LIF group (20 mice) and light damage+ PBS group (20 mice). Four days before exposing to light, the right eye of each animal in light damage+ LIF group and light damage+ PBS group was injected with LIF and PBS, respectively; then the mice in the light damage+ LIF group and light damage+ PBS group were exposed to 4 000 lx intensity of cool white fluorescent light for 4 hours to establish the experimental model of retinal light damage.The function and morphology of retinal photoreceptor cells were detected by flash electroretinogram (fERG) and histopathological examination.Real-time PCR was used to detect the mRNA expression of Jak3, STAT3, and apoptosis-related factor Bcl-2 and Bax.The use of animals is guided by the State Science and Technology Commission's regulations on the management of experimental animals. Results The amplitudes of scotopic ERG a wave of 0.01, 1, 100, 200, 400 cd·s/m2 light in the light damage+ PBS group were significantly lower than those in the normal control group and light damage+ LIF group (all at P<0.05). The amplitudes of photopic ERG b wave of different color light in the light damage+ PBS group were significantly lower than those in the normal control group and light damage+ LIF group (all at P<0.05). The number of photoreceptor nuclei in the light damage+ PBS group was significantly lower than that in the normal control group and light damage+ LIF group (both at P<0.05). Compared with light damage+ PBS group, the relative expression of Jak3, STAT3, Bcl-2 mRNA in light damage+ LIF group were significantly increased (all at P<0.05), and the relative expression of Bax mRNA were significantly decreased (P<0.05). Conclusions LIF can protect retinal photoreceptor cells from light damage, which may result from the activation of Jak3/STAT3 signaling pathway and inhibition of its downstream Bax/Bcl-2 apoptotic pathway. Key words: Leukemia inhibitory factor; Photoreceptor; Light damage; Neuroprotection

Abstract WMP77: Anti-Inflammatory Signaling by Leukemia Inhibitory Factor is Suppressed in Aged Animals After Stroke

Objective: To determine whether the anti-inflammatory effects of leukemia inhibitory factor (LIF) are altered in aged male and female rats. Methods: Focal ischemia was induced in 3 month old male and 18 month old male/female Sprague-Dawley using the middle cerebral artery occlusion (MCAO) procedure. Animals were treated with PBS or LIF at 6, 24, and 48 h after MCAO (125 μg/kg). Infarct volume in aged animals was quantified with T2-weighted MRI. Functional motor skills were assessed immediately prior to euthanization at 72 h post-MCAO. Protein levels of CD11b and IL-12 p40 in brain and spleen tissue were measured using immunoblotting. Results: At 72 h, there was a trend towards decreased infarct volume in aged male (189 ± 45OD; n=4) and female LIF-treated rats (104 ± 71 OD; n=4) compared to PBS-treated aged male (188 ± 45; n=4) and female rats (179 ± 72; n=5). LIF-treated aged female rats showed significant decreases in circling (p=0.0209) and body swing bias (p=0.05) compared to the PBS-treated aged females. Normalized CD11b levels were significantly in LIF-treated young males (1.1 ± 0.3 OD; n=5) compared to PBS-treated young males (2.5 ± 0.5 OD; n=6; p&lt;0.05). Although aged male (1.2 ± 0.4 OD) and females (1.2 ± 0.3 OD) had lower levels of CD11b in the brain 72 h post-MCAO compared to young males, LIF had no effect on brain CD11b levels in aged rats. LIF increased spleen size (1.6 ± 0.1 g) and splenic CD11b levels (0.11 ± 0.01 OD) compared to PBS-treated females (0.6 ± 0.1 g; 0.08 ± 0.01 OD; p&lt;0.05), and there was a significant positive correlation between these two factors in the aged female rats (r = 0.6775; p&lt;0.05). Furthermore, IL-12 p40 levels in splenic tissue were significantly higher in young male PBS-treated rats (0.38 ± 0.06 OD) compared to aged male (0.12 ± 0.01 OD; p&lt;0.01) and female rats (0.16 ± 0.04 OD; p&lt;0.01). LIF treatment reduced IL-12 p40 levels in the spleen in young rats (0.24 ± 0.04; p&lt;0.05) but not in either of the aged rat groups. Conclusions: LIF is more effective at decreasing splenic IL-12 expression and immune cell infiltration in young rats compared to aged rats. However, LIF counteracts the post-stroke splenic response in aged females but not aged male rats.

Protective Effects of Leukemia Inhibitory Factor on Retinal Vasculature and Cells in Streptozotocin-induced Diabetic Mice.

Background:Leukemia inhibitory factor (LIF) has been reported to possess various pharmacological effects, including displaying vascular and neuroprotective properties, during retinal disease. The aim of this study was to investigate the vascular and structural changes in the retina of diabetic mice and to explore whether LIF prevents experimental diabetes-induced retinal injury in the early stages.Methods:Diabetes was induced in C57Bl/6J mice with streptozotocin (STZ) injections. Successful diabetic animal models were randomly separated into two groups: the diabetic group (n = 15) and the LIF-treated group (n = 15). Normal C57BL/6 mice served as the normal control group (n = 14). Recombinant human LIF was intravitreally injected 8 weeks after the diabetic model was successfully established. Retinas were collected and evaluated using histological and immunohistochemical techniques, and flat-mounted retinas and Western blotting were performed at 18 weeks after the induction of diabetes and 2 days after the intravitreal injection of LIF. The analysis of variance test were used.Results:Histological analysis showed that there were fewer retinal ganglion cells (RGCs) and the inner nuclear layer (INL) became thinner in the diabetic model group (RGC 21.8 ± 4.0 and INL 120.2 ± 4.6 μm) compared with the normal control group (RGC 29.0 ± 6.7, t = −3.02, P = 0.007; INL 150.7 ± 10.6 μm, t = −8.88, P < 0.001, respectively). After LIF treatment, the number of RGCs (26.9 ± 5.3) was significantly increased (t = 3.39, P = 0.030) and the INL (134.5 ± 14.2 μm) was thicker compared to the diabetic group (t = 2.75, P = 0.013). In the anti-Brn-3a-labeled retinas, the number of RGCs in the LIF-treated group (3926.0 ± 143.9) was obviously increased compared to the diabetic group (3507.7 ± 286.1, t = 2.38, P = 0.030), while no significance was found between the LIF-treated group and the control group (4188.3 ± 114.7, t = −2.47, P = 0.069). Flat-mounted retinas demonstrated that a disorganized, dense distribution of the vessel was prominent in the diabetic model group. Vessel distribution in the LIF-treated mouse group was typical and the thickness was uniform. The levels of phosphosignal transducer and activator of transcription 3 activation were obviously higher in the LIF-injected retinas than those in the diabetic control group (t = 3.85, P = 0.019) and the normal control (t = −3.20, P = 0.019).Conclusion:The present study provides evidence that LIF treatment protects the integrity of the vasculature and prevents retinal injury in the early stages of diabetic retinopathy in STZ-induced diabetic models.

Leukemia inhibitory factor increases the proliferation of human endometrial stromal cells and expression of genes related to pluripotency

Concerning the low population of human endometrial mesenchymal cells within the tissue and their potential application in the clinic and tissue engineering, some researches have been focused on their in vitro expansion. The aim of this study was to evaluate the effect of leukemia inhibitory factor (LIF) as a proliferative factor on the expansion and proliferation of human endometrial stromal cells. In this experimental study, the isolated and cultured human endometrial stromal cells from women at ovulatory phase aged 20-35 years, after fourth passage were divided into control and LIF-treated groups. In the experimental group, the endometrial cells were treated by 10 ng/ml LIF in culture media and the cultured cells without adding LIF considered as control group. Both groups were evaluated and compared for proliferation rate using MTT assay, for CD90 marker by flow cytometric analysis and for the expression of Oct4, Nanog, PCNA and LIFr genes using real-time RT-PCR. The proliferation rate of control and LIF-treated groups were 1.17±0.17 and 1.61±0.06 respectively and there was a significant increase in endometrial stromal cell proliferation following in vitro treatment by LIF compared to control group (p=0.049). The rate of CD90 positive cells was significantly increased in LIF-treated group (98.96±0.37%) compared to control group (94.26±0.08%) (p=0.0498). Also, the expression ratio of all studied genes was significantly increased in the LIF-treated group compared to control group (p=0.0479). The present study showed that LIF has a great impact on proliferation, survival, and maintenance of pluripotency of human endometrial stromal cells and it could be applicable in cell therapies.

Leukemia inhibitory factor (LIF) potentiates antinociception activity and inhibits tolerance induction of opioids

BackgroundThe efficacy of opioids typically decreases after long-term use owing to the development of tolerance. Glial activation and the upregulation of proinflammatory cytokines are related to the induction of tolerance. We investigated the effect of leukemia inhibitory factor (LIF) on morphine analgesia and tolerance. MethodsLIF concentrations in rat spinal cords were measured by polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay (ELISA) after morphine administration. LIF distribution was examined using confocal microscopy. To evaluate the effects of LIF on morphine analgesia and tolerance, LIF was intrathecally administered 30 min before morphine injection. The analgesic effect of morphine was evaluated by measuring tail-flick latency. Human LIF concentrations from the cerebrospinal fluid (CSF) of opioid tolerant patients were also determined by specific ELISA. ResultsChronic morphine administration upregulated LIF concentrations in rat spinal cords. Intrathecal injection of LIF potentiated the analgesic action of morphine. Patch clamp recording of spinal cord slices showed that LIF enhanced DAMGO ([D-Ala2, N-MePhe4, Gly-ol]-enkephalin)-induced outward potassium current. The development of tolerance was markedly suppressed by exogenous LIF, whereas neutralizing the endogenously released LIF with anti-LIF antibodies accelerated the tolerance induction. Moreover, LIF concentrations in the CSF of opioid-tolerant patients were higher than those in the opioid-naive controls. ConclusionsIntrathecal administration of LIF potentiated morphine antinociceptive activity and attenuated the development of morphine tolerance. Upregulation of endogenously released LIF by long-term use of opioids might counterbalance the tolerance induction effects of other proinflammatory cytokines. LIF might be a novel drug candidate for inhibiting opioid tolerance induction.

Effects of Leukemia Inhibitory Factor Combined with Basic Fibroblast Growth Factor on Self-maintenance and Self-renewal of Human Umbilical Cord Mesenchymal Stem Cells In Vitro

To study the effects of LIF combined with bFGF on the proliferation, stemness and senescence of hUC-MSC. Experiments were divided into 4 groups: control group, in which the cells were treated with complete medium (α-MEM containing 10% FBS); group LIF, in which the cells were treated with complete medium containing 10 ng/ml LIF; group bFGF, in which the cells were treated with complete medium containing 10 ng/ml bFGF; combination group, in which the cells were treated with complete medium containing 10 ng/ml LIF and 10 ng/ml bFGF. The growth curves of hUC-MSC at passage 4 in different groups were assayed by cell counting kit 8. Cellular morphologic changes were observed under inverted phase contrast microscope; hUC-MSC senescence in different groups was detected by β-galactosidase staining. The expression of PCNA, P16, P21, P53, OCT4 and NANOG genes was detected by RT-PCR. The cell growth curves of each group were similar to the S-shape; the cell proliferation rate from high to low as follows: that in the combination group > group bFGF > group LIF > control group. Senescence and declining of proliferation were observed at hUC-MSC very early in control group; the cells in group LIF maintained good cellular morphology at early stage, but cell proliferation was slow and late senescence was observed; a few cells in group bFGF presented signs of senescence, but with quick proliferation; the cells in combination group grew quickly and maintained cellular morphology of hUC-MSC for long time. The LIF and bFGF up-regulated the expression of PCNA, OCT4 and NANOG, while they down-regulated the expression of P16, P21, P53, and their combinative effects were more significant. LIF combined with bFGF not only can promote the proliferation and maintenance of stemness of hUC-MSC, but also can delay the senescence of hUC-MSC.

Developmental Stage-Dependent Effects of Leukemia Inhibitory Factor on Adipocyte Differentiation of Murine Bone Marrow Stromal Cells.

Studies describing the effects of leukemia inhibitory factor (LIF) on adipocyte differentiation in murine cells have shown varying results. For example, LIF has been reported to have a suppressive effect on adipocyte differentiation in the 3T3-L1 cell line, whereas it promoted adipocyte differentiation in the Ob1771 and 3T3-F442A cell lines. Thus, it is possible that the effects of LIF on adipogenesis vary with the developmental stage of the cells or tissues, but the details remain unclear. To further elucidate the role of LIF in adipogenesis, we investigated the effects of LIF on murine bone marrow stromal cells at the early and late stages of adipogenesis. LIF decreased the number of lipid foci and suppressed the expression levels of adipocyte differentiation markers at day 5; however, it enhanced these same traits at day 15. A previous report showed that the expression levels of Wnt signaling molecules are different at the early and late differentiation stages; therefore, we investigated the relationship between LIF and Wnt signaling. LIF affected the mRNA expression levels of different Wnt signaling molecules but inhibited the expression level of β-catenin protein at both days 5 and 15. Our data suggest that LIF has reciprocal roles during the early and late stages of adipocyte differentiation, regulating the Wnt signaling pathway.

Analysis of the Effect of Leukemia Inhibitory Factor on Follicular Growth in Cultured Murine Ovarian Tissue.

Leukemia inhibitory factor (LIF) is expressed in the ovary and controls follicular growth. LIF has been reported to accelerate the primordial to primary follicle transition, the growth of cultured preantral follicles, and the maturation of oocytes. Previous reports on factors that regulate follicular growth have largely employed cultured follicles. However, there are several types of follicles and somatic cells in the ovary that are likely to interact with one another to regulate follicular growth. Therefore, a novel approach is essential for understanding the function of factors that regulate follicular growth in the ovary. In this study, we evaluated the function of LIF using cultured ovarian tissue. Ovarian tissue slices were cultured in the presence or absence of recombinant LIF and neutralizing anti-LIF antibody to enable continuous monitoring of follicular growth within the context of the ovary as well as analysis of the process of follicular growth. The results revealed that LIF inhibited the growth of primary, secondary, and antral follicles. Furthermore, we verified the inhibitory function of LIF using the neutralizing antibody, which accelerated follicular growth. These results suggest that LIF is likely to coordinate follicular growth in the ovary. The culture and analysis methods employed in this study are thus effective for clarifying the tissue-level functions of factors that regulate follicular growth within the ovary.

Effects of leukemia inhibitory factor and insulin-like growth factor-I on the cell allocation and cryotolerance of bovine blastocysts

The present study examined the developmental capacity and cryotolerance of cultured bovine embryos in defined media (synthetic oviduct fluid, SOF) supplemented with insulin-like growth factor I (IGF-I) and leukemia inhibitor factor (LIF). The objectives of the present study were: (1) to examine the effects IGF-I and LIF on bovine embryo development potential and (2) to investigate the cryotolerance and survivability of vitrified blastocysts obtained from embryos cultured in a defined media. We studied the development of bovine embryos produced in vitro and cultured (in four different treatments) until Day 7 after fertilization. In Experiment 1, zygotes were cultured to the blastocyst stage and differentially stained for determine the count of cells. In Experiment 2, zygotes were vitrified before staining. LIF alone or combined with IGF-I was significantly effective on in vitro bovine embryo development especially ratio to reach blastocyst. The cells for both ICM and TE decreased by the effect of freezing in all treatment groups in the Experiment 2 compared with Experiment 1. Interestingly, the LIF treatment showed fewest variations. In addition to this, for average number of ICM and TE cells, LIF treatment showed fewest variation compared with other treatments (ICM: 23.5 vs 19.5, TE: 53.6 vs 51). These results are the first to demonstrate that the addition of IGF-I along with LIF to the culture medium was found to be beneficial for bovine embryonic development based on cellular cryotolerance after vitrification.

Leukemia inhibitory factor and fibroblast growth factor 2 critically and mutually sustain pluripotency of rabbit embryonic stem cells.

Effects of leukemia inhibitory factor (LIF) and fibroblast growth factor 2 (FGF2) on establishment and maintenance of rabbit embryonic stem cell (rESC) lines were assessed. When grown on MEF feeders, rESC lines derived from fertilized embryos were established and maintained in medium containing paracrine factors LIF (via STAT3) and/or FGF2 (via MEK-ERK1/2 and PI3K-AKT). However, high levels of ERK1/2 and AKT activities in rESCs were crucial for maintaining their undifferentiated proliferation. Although rESCs under the influence of either LIF (500, 1,000, and 2,000 U/ml) or FGF2 (5, 10, and 20 ng/ml) alone had enhanced expression of pluripotency markers, peak expression occurred when both LIF (1,000 U/ml) and FGF2 (10 ng/ml) were applied. Induced dephosphorylation of STAT3, ERK1/2, and AKT by specific inhibitors limited growth of rESCs and caused remarkable losses of self-renewal capacity; therefore, we inferred that STAT3, ERK, and AKT had essential roles in maintaining rESC proliferation and self-renewal. We concluded that LIF and FGF2 jointly maintained the undifferentiated state and self-renewal of rESCs through an integrative signaling module.

Leukemia inhibitory factor enhances bovine oocyte maturation and early embryo development

The present study was conducted to examine the effects of leukemia inhibitory factor (LIF) on bovine oocyte maturation and early embryo development in vitro. Results showed that LIF supplementation (25 ng/ml) enhanced nuclear maturation of intact cumulus-oocyte complexes (COCs) compared to the vehicle control. Similar results were observed in denuded oocytes, indicating that LIF directly influences oocyte development. LIF-treated oocytes showed a higher cortical-granule-migration rate and increased expression of CD9, a tetraspanin transmembrane protein essential for fertilization. After in vitro fertilization, oocytes receiving LIF supplementation exhibited a higher cleavage rate and yielded a significantly higher number of blastocysts. To further dissect the molecular mechanism underlying this LIF-induced bovine oocyte maturation phenotype, we examined the involvement of two signaling cascades, mitogen-activated protein kinases (MAPK3/1)- and the signal transducer and activator of transcription 3 (STAT3)-dependent pathways. Western blot results revealed that LIF phosphorylated MAPK3/1 and STAT3. Inhibition of MAPK3/1 activation with MEK inhibitor U0126 only partially blocked LIF-induced nuclear maturation, although it attenuated oocyte cytoplasmic maturation. Inhibition of JAK/STAT3 activation with a specific pharmacological inhibitor completely abolished the LIF-response in bovine oocyte. In summary, these data revealed a novel role for LIF in bovine oocyte maturation subsequent embryonic development.

Effects of leukemia inhibitory factor on transcript expression of pluripotent genes in bovine embryonic stem like cells

Leukemia inhibitory factor (Lif) is very important for embryonic stem cell establishment. In this study, we investigated effects of Lif on transcript expression of pluripotent genes of bovine embryonic stem like cells in passage 1, passage 3 and passage 6. The results showed that Lif supplementation of medium could improve transcript expression of pluripotent gene including nanog, oct4, sox2 and c-myc. Three Lif concentrations were applied for cell culture medium. We found that pluripotent gene transcripts were highest expressed in 103 IU/ml Lif supplemented medium, especially nanog and oct4 transcript expression could be maintained until 6th passage . The transcript expression was decreased in 104 IU/ml Lif suppmented medium, suggesting that high concentration of Lif could inhibit pluripotent gene expression. Thus, 103 IU/ml Lif was the most efficient concentration to improve transcript expression of pluripotent genes. There was a relationship in nanog expression and c-myc and sox2 expression. C-myc and sox2 expression were up-regulated when nanog was down-regulated. We also accessed nanog or oct4 which were key factors for the maintenace of pluripotency and renewal of bovine embryonic stem like cell. The result demonstrated that nanog could be the key factor for pluripotency of bovine embryonic stem like cells.

Leukemia inhibitory factor stimulates muscle glucose uptake by a PI3‐kinase dependent pathway that is maintained in white muscle in obesity (1162.4)

OBJECTIVE: To investigates the metabolic effects of leukemia inhibitory factor (LIF) in mouse skeletal muscle.METHODS: Effects of LIF on muscle glucose transport, palmitate oxidation and cellular signaling were investigated in soleus and extensor digitorum longus (EDL) muscles from chow and highfat diet fed wildtype (WT) mice or chow fed muscle‐specific AMPKα2 kinase‐dead (KD) and suppressors of cytokine signaling (SOCS) 3 muscle‐specific knockout mice.RESULTS: LIF increased muscle glucose transport in a dose‐ and time‐dependent manner. LIF increased Akt Ser473‐P, whereas AMPK Thr172‐P was unaffected. Incubation of muscles from KD or WT mice with Wortmannin, LY294002 and Parthenolide demonstrated that PI3‐kinase, but not AMPK, was essential for LIF‐stimulated glucose transport. Incubation with Rapamycin and AZD8055 demonstrated that mammalian target of rapamycin complex (mTORC)2 and not mTORC1 is necessary for LIF‐stimulated glucose transport. LIF‐stimulated glucose transport was maintained in EDL muscle from obese insulin resistant mice. Lack of SOCS3 did not affect LIF‐stimulated glucose uptake.CONCLUSIONS: LIF acutely increases muscle glucose transport by a mechanism involving the PI3‐kinase/mTORC2/Akt pathway which is maintained in EDL muscle from obese insulin resistant mice.