| Reference | 1. Cell Tissue Res. 2015 Feb;359(2):537-545. doi: 10.1007/s00441-014-2025-3. Epub
2014 Nov 4.
<br>
U0126 promotes osteogenesis of rat bone-marrow-derived mesenchymal stem cells by
activating BMP/Smad signaling pathway.
<br>
Xu L(1), Liu Y(1), Hou Y(2), Wang K(1), Wong Y(1), Lin S(1), Li G(3)(4)(5)(6).
<br>
Author information: <br>
(1)Department of Orthopaedics & Traumatology, Prince of Wales Hospital, The
Chinese University of Hong Kong, Hong Kong, People/’s Republic of China.
(2)School of Biomedical Sciences, Li Ka Shing Institute of Health Sciences, The
Chinese University of Hong Kong, Hong Kong, People/’s Republic of China.
(3)Department of Orthopaedics & Traumatology, Prince of Wales Hospital, The
Chinese University of Hong Kong, Hong Kong, People/’s Republic of China.
[email protected].
(4)MOE Key Laboratory of Regenerative Medicine, School of Biomedical Sciences,
The Chinese University of Hong Kong, Shatin, Hong Kong, People/’s Republic of
China. [email protected].
(5)The CUHK-ACC Space Medicine Centre on Health Maintenance of Musculoskeletal
System, Shenzhen Research Institute, The Chinese University of Hong Kong,
Shenzhen, People/’s Republic of China. [email protected].
(6)Li Ka Shing Institute of Health Institute, Prince of Wales Hospital, The
Chinese University of Hong Kong, Room 904, 9/F, Shatin, Hong Kong, SAR, People/’s
Republic of China. [email protected].
<br>
U0126 has been reported as a specific inhibitor of the ERK1/2 signaling pathway,
which plays a vital role during the osteogenic differentiation of mesenchymal
stem cells (MSCs). We report the positive effect of U0126 on the osteogenesis of
rat MSCs. We find that U0126 promotes the osteogenic differentiation of rat MSCs
as demonstrated by the quantitative real-time polymerase chain reaction for
osteogenic markers, alkaline phosphatase activity and calcium nodule formation.
Our data indicate that U0126 enhances the BMP/Smad signaling pathway in rat MSCs,
while inhibiting the ERK1/2 signaling pathway. Furthermore, Western blot results
demonstrate that U0126 increases Smad1/5/8 phosphorylation synergistically with
β-glycerophosphate. In addition, U0126 significantly increases the expression of
BMP2 during the process of osteogenesis in rat MSCs and the level of
phosphorylated Smad1/5/8 is significantly reduced by BMP2 antibody, suggesting
that U0126 also promotes the expression of BMP2 to enhance Smad proteins
phosphorylation. Thus, we demonstrate a novel function for U0126 in promoting
osteogenic differentiation of rat MSCs by the activation of the BMP/Smad
signaling pathway.
<br>
2. J Autoimmune Disord. 2015;1(1). pii: 4. Epub 2015 Nov 7.
<br>
U0126, an Inhibitor of MEK1/2, Increases Tumor Necrosis Factor-α-Induced
Apoptosis, but not Interleukin-6 Induced Apoptosis in C-28/I2 Human Chondrocytes.
<br>
Malemud CJ(1), Lewis AC(2), Wylie MA(2), Meszaros EC(2), Skomorovska-Prokvolit
Y(3), Mesiano S(3).
<br>
Author information: <br>
(1)Arthritis Research Laboratory, Department of Medicine, Division of Rheumatic
Diseases; Department of Anatomy, Case Western Reserve University School of
Medicine, Cleveland, Ohio 44106 USA.
(2)Arthritis Research Laboratory, Department of Medicine, Division of Rheumatic
Diseases.
(3)Department of Reproductive Biology, Case Western Reserve University School of
Medicine, Cleveland, Ohio 44106 USA.
<br>
BACKGROUND: Activation of the SAPK/MAPK signaling pathway by pro-inflammatory
cytokines is known to induce apoptosis in cultured articular chondrocytes.
C-28/I2, an immortalized human juvenile chondrocyte cell line was employed to
determine the extent to which recombinant human (rh) forms of the
pro-inflammatory cytokines, tumor necrosis factor-α (rhTNF-α,), interleukin-6
(rhIL-6) and oncostatin M (rhOSM) induced apoptosis.<br>
METHODS: The induction of apoptosis in the presence or absence of these cytokines
was measured by the DAPI/TUNEL assay, by whether or not pro-caspase-3 was
activated and by the extent to which poly-ADP-ribose polymerase (PARP) was
degraded.<br>
FINDINGS: Only rhTNF-α, and rhIL-6 significantly increased apoptosis in C-28/I2
chondrocytes, although rhOSM exhibited a strong trend (p=0.067) towards
increasing the frequency of apoptotic chondrocytes. The number of apoptotic
C28/I2 chondrocytes was significantly increased (p=1.3 × 10-5) by the combination
of rhTNF-α and U0126 (10 μM) compared to rhTNF-α alone. However apoptosis was not
further increased by combining rhIL-6 with U0126. The LI-COR® western blot system
showed that U0126 (10 μM) inhibited the phosphorylation of extracellular
signal-regulated kinase-2 (p-ERK2) by phorbol myristate acetate-treated
immortalized myometrial cells, U0126 (10 μM) did not alter total U-ERK2. Western
blot analysis also revealed that the increased frequency of apoptotic C-28/I2
chondrocytes induced by rhTNF-α and rhOSM, but not rhIL-6, was associated with
PARP degradation. However, none of the cytokines resulted in pro-caspase-3
activation.<br>
CONCLUSION: These results showed that rhTNF-α and rhIL-6 were strong inducers of
apoptosis in the immortalized C-28/I2 human chondrocyte cell line. They also
suggested that inhibiting ERK2 phosphorylation via U0126-mediated inhibition of
MEK1/2 activity, increased rhTNF-α-induced C-28/I2 chondrocyte apoptosis.
<br>
3. Xi Bao Yu Fen Zi Mian Yi Xue Za Zhi. 2014 Jul;30(7):717-20.
<br>
[Wortmannin and U0126 inhibit the promoting effect of insulin on differentiation
of skeletal myoblasts in rats].
<br>
Zhou X(1), Zhao Y(2), Xu L(2), Li X(2), Chen P(2), Zou H(2), Yu H(2).
<br>
Author information: <br>
(1)Jiangxi Key Laboratory of System Biomedicine, Poyang Lake Eco-economy Research
Center, Jiujiang University, Jiujiang 332000, China.
(2)Jiangxi Key Laboratory of System Biomedicine, Jiujiang 332000, China.
<br>
OBJECTIVE: To verify whether insulin promotes the differentiation of skeletal
myoblasts into myocytes and whether wortmannin and U0126 inhibit the promoting
effect with an attempt to explore the molecular mechanisms of inducing the
differentiation of muscular cells in rats.<br>
METHODS: Primary skeletal myoblasts were separated and cultured from rats, and
then were treated in DMEM containing various concentrations of insulin. The
morphology of cells was monitored under a phase-contrast microscope. And the
expression of myogenin was detected by immunocytochemistry and Western blotting.
The change in the effect of insulin on the differentiation of myoblasts was
observed after the intervention of a phosphatidylinositide 3-kinase (PI3K)
inhibitor wortmannin and a specific MEK inhibitor U0126.
RESULTS: Insulin markedly promoted myotube formation of myoblasts. Two days after
insulin treatment, myotubes started to form; later, more and more myotubes
appeared, and to the peak at 7 days. Insulin increased the expression of myogenin
in a concentration-dependent manner. However, wortmannin and U0126 inhibited the
effect of insulin on the differentiation of skeletal myoblasts in rats.
CONCLUSION: Wortmannin and U0126 can suppress the promoting effect of insulin on
the differentiation of skeletal myoblasts into myocytes in rats and decrease the
formation of myotubes and the expression of myogenin.
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