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Increased expression of surface CD44 in hypoxia-DCs skews helper T cells toward a Th2 polarization.

Yang M, Liu Y, Ren G, Shao Q, Gao W, Sun J, Wang H, Ji C, Li X, Zhang Y, Qu X - Sci Rep (2015)

Bottom Line: However, the underlying mechanisms still remain largely unknown.In this study, we found the over-expression of surface CD44 in DCs was involved in this process via ligand binding.Moreover, KIF2A expression was found negatively regulated by HIF-1α in hypoxic microenvironment.

View Article: PubMed Central - PubMed

Affiliation: Institute of Basic Medical Sciences, Qilu Hospital, Shandong University, Jinan, 250012, Shandong, China.

ABSTRACT
A low partial oxygen pressure (hypoxia) occurs in many pathological environments, such as solid tumors and inflammatory lesions. Understanding the cellular response to hypoxic stress has broad implications for human diseases. As we previously reported, hypoxia significantly altered dendritic cells (DCs) to a DC2 phenotype and promoted a Th2 polarization of naïve T cells with increased IL-4 production. However, the underlying mechanisms still remain largely unknown. In this study, we found the over-expression of surface CD44 in DCs was involved in this process via ligand binding. Further investigation showed hypoxia could reduce the surface expression of membrane type 1 metalloprotease (MT1-MMP) via down-regulating the kinesin-like protein KIF2A, which subsequently alleviated the shedding of CD44 from DCs. Moreover, KIF2A expression was found negatively regulated by HIF-1α in hypoxic microenvironment. These results suggest a previously uncharacterized mechanism by which hypoxia regulates the function of DCs via KIF2A/MT1-MMP/CD44 axis, providing critical information to understand the immune response under hypoxia.

No MeSH data available.


Related in: MedlinePlus

Knockdown of HIF-1α by specific siRNA up-regulated KIF2A mRNA expression in hypoxic mature DCs.(a,b) DCs were induced under hypoxia and matured by LPS. (a) Expression of HIF-1α mRNA was accessed by qRT-PCR. Results are shown as fold changes relative to mRNA levels in hypoxic imDCs and represent the average of three independent experiments. (b) Protein level of HIF-1α expression in imDCs and mDCs was detected by western blot with specific antibody. (c–f) Hypoxic imDCs were either electroporated with HIF-1α siRNA or negative control (NC) siRNA and LPS was added to induce DCs maturation. After 48 h, HIF-1α(c) or KIF2A (e) mRNA expression in mDCs was determined by qRT-PCR. The results are expressed as the fold mRNA levels of negative control siRNA treated DCs (arbitrarily defined as 1) of three independent experiments. Western blot was also performed to analyze the protein expression of HIF-1α (d) and KIF2A (f). *P < 0.05.
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f4: Knockdown of HIF-1α by specific siRNA up-regulated KIF2A mRNA expression in hypoxic mature DCs.(a,b) DCs were induced under hypoxia and matured by LPS. (a) Expression of HIF-1α mRNA was accessed by qRT-PCR. Results are shown as fold changes relative to mRNA levels in hypoxic imDCs and represent the average of three independent experiments. (b) Protein level of HIF-1α expression in imDCs and mDCs was detected by western blot with specific antibody. (c–f) Hypoxic imDCs were either electroporated with HIF-1α siRNA or negative control (NC) siRNA and LPS was added to induce DCs maturation. After 48 h, HIF-1α(c) or KIF2A (e) mRNA expression in mDCs was determined by qRT-PCR. The results are expressed as the fold mRNA levels of negative control siRNA treated DCs (arbitrarily defined as 1) of three independent experiments. Western blot was also performed to analyze the protein expression of HIF-1α (d) and KIF2A (f). *P < 0.05.

Mentions: Since HIF-1α is a key mediator for hypoxia and it regulates a wide spectrum of biological processes and downstream targets33, we supposed the suppression of KIF2A in mDCs under hypoxia might also be mediated by HIF-1α activation. HIF-1α mRNA was detected in hypoxic imDCs; after LPS stimulation, HIF-1α expression in both mRNA and protein level became stronger in hypoxic mDCs (Fig. 4a,b), which was consistent with the findings by other groups in murine DCs3435. To investigate whether the elevation of HIF-1α affected KIF2A expression in hypoxia-mDCs, specific siRNA targeting HIF-1α was used during DCs maturation under hypoxia. As expected, HIF-1α siRNA significantly reduced the mRNA and protein level of HIF-1α in hypoxic mDCs (Fig. 4c,d). KIF2A mRNA expression was increased by approximately 60% in hypoxia mDCs treated with HIF-1α siRNA compared to negative control siRNA treated group (Fig. 4e) as well as stronger expression of KIF2A protein was demonstrated by western blot (Fig. 4f). These results indicated the inhibition of KIF2A in mDCs under hypoxia was regulated by HIF-1α.


Increased expression of surface CD44 in hypoxia-DCs skews helper T cells toward a Th2 polarization.

Yang M, Liu Y, Ren G, Shao Q, Gao W, Sun J, Wang H, Ji C, Li X, Zhang Y, Qu X - Sci Rep (2015)

Knockdown of HIF-1α by specific siRNA up-regulated KIF2A mRNA expression in hypoxic mature DCs.(a,b) DCs were induced under hypoxia and matured by LPS. (a) Expression of HIF-1α mRNA was accessed by qRT-PCR. Results are shown as fold changes relative to mRNA levels in hypoxic imDCs and represent the average of three independent experiments. (b) Protein level of HIF-1α expression in imDCs and mDCs was detected by western blot with specific antibody. (c–f) Hypoxic imDCs were either electroporated with HIF-1α siRNA or negative control (NC) siRNA and LPS was added to induce DCs maturation. After 48 h, HIF-1α(c) or KIF2A (e) mRNA expression in mDCs was determined by qRT-PCR. The results are expressed as the fold mRNA levels of negative control siRNA treated DCs (arbitrarily defined as 1) of three independent experiments. Western blot was also performed to analyze the protein expression of HIF-1α (d) and KIF2A (f). *P < 0.05.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4555176&req=5

f4: Knockdown of HIF-1α by specific siRNA up-regulated KIF2A mRNA expression in hypoxic mature DCs.(a,b) DCs were induced under hypoxia and matured by LPS. (a) Expression of HIF-1α mRNA was accessed by qRT-PCR. Results are shown as fold changes relative to mRNA levels in hypoxic imDCs and represent the average of three independent experiments. (b) Protein level of HIF-1α expression in imDCs and mDCs was detected by western blot with specific antibody. (c–f) Hypoxic imDCs were either electroporated with HIF-1α siRNA or negative control (NC) siRNA and LPS was added to induce DCs maturation. After 48 h, HIF-1α(c) or KIF2A (e) mRNA expression in mDCs was determined by qRT-PCR. The results are expressed as the fold mRNA levels of negative control siRNA treated DCs (arbitrarily defined as 1) of three independent experiments. Western blot was also performed to analyze the protein expression of HIF-1α (d) and KIF2A (f). *P < 0.05.
Mentions: Since HIF-1α is a key mediator for hypoxia and it regulates a wide spectrum of biological processes and downstream targets33, we supposed the suppression of KIF2A in mDCs under hypoxia might also be mediated by HIF-1α activation. HIF-1α mRNA was detected in hypoxic imDCs; after LPS stimulation, HIF-1α expression in both mRNA and protein level became stronger in hypoxic mDCs (Fig. 4a,b), which was consistent with the findings by other groups in murine DCs3435. To investigate whether the elevation of HIF-1α affected KIF2A expression in hypoxia-mDCs, specific siRNA targeting HIF-1α was used during DCs maturation under hypoxia. As expected, HIF-1α siRNA significantly reduced the mRNA and protein level of HIF-1α in hypoxic mDCs (Fig. 4c,d). KIF2A mRNA expression was increased by approximately 60% in hypoxia mDCs treated with HIF-1α siRNA compared to negative control siRNA treated group (Fig. 4e) as well as stronger expression of KIF2A protein was demonstrated by western blot (Fig. 4f). These results indicated the inhibition of KIF2A in mDCs under hypoxia was regulated by HIF-1α.

Bottom Line: However, the underlying mechanisms still remain largely unknown.In this study, we found the over-expression of surface CD44 in DCs was involved in this process via ligand binding.Moreover, KIF2A expression was found negatively regulated by HIF-1α in hypoxic microenvironment.

View Article: PubMed Central - PubMed

Affiliation: Institute of Basic Medical Sciences, Qilu Hospital, Shandong University, Jinan, 250012, Shandong, China.

ABSTRACT
A low partial oxygen pressure (hypoxia) occurs in many pathological environments, such as solid tumors and inflammatory lesions. Understanding the cellular response to hypoxic stress has broad implications for human diseases. As we previously reported, hypoxia significantly altered dendritic cells (DCs) to a DC2 phenotype and promoted a Th2 polarization of naïve T cells with increased IL-4 production. However, the underlying mechanisms still remain largely unknown. In this study, we found the over-expression of surface CD44 in DCs was involved in this process via ligand binding. Further investigation showed hypoxia could reduce the surface expression of membrane type 1 metalloprotease (MT1-MMP) via down-regulating the kinesin-like protein KIF2A, which subsequently alleviated the shedding of CD44 from DCs. Moreover, KIF2A expression was found negatively regulated by HIF-1α in hypoxic microenvironment. These results suggest a previously uncharacterized mechanism by which hypoxia regulates the function of DCs via KIF2A/MT1-MMP/CD44 axis, providing critical information to understand the immune response under hypoxia.

No MeSH data available.


Related in: MedlinePlus