Cbl-b inhibited CD4+ T cell activation by regulating the expression of miR-99a/miR-125b
Mengyun Wu1, Xiu Gao1, Yuxu Tang1
1Institutes of Biology and Medical Sciences, Soochow University, Suzhou, People's Republic of China.
Abstract:
The molecular regulation of T cell activation has always been a hot topic in immunology. It has been reported that Cbl-b inhibits T cell activation, but the specific molecular mechanism especially for transcriptional regulation has not been very clear so far. Our present study showed that ablation of Cbl-b resulted in the increased expression of miR-99a and miR-125b, and the antagonism of miR-99a or miR-125b could inhibit the Cbl-b-/- T cell over-activation partly. Further study demonstrated that Cbl-b could bind and ubiquitinate SHP-2 in the activated T cells. The activation of SHP-2 deficient T cells was significantly inhibited. Western blot showed that SHP-2 could dephosphorylate HOXA10, and HOXA10 could enter the nucleus under the stimulation of anti-CD3 antibody alone in Cbl-b deficient T cells. Luciferase reporter assay and CUT&Tag qPCR showed that HOXA10 could regulate the expression of miR-99a/miR-125b. Real-time PCR and western blot further indicated that miR-99a/miR-125b functioned on PI3K/AKT pathway to regulate T cell activation. In conclusion, our study demonstrated that Cbl-b ubiquitinated SHP-2 to arrest HOXA10-mediated CD4+ T cell activation by regulating the expression of miR-99a/miR-125b and their function on PI3K/AKT pathway, which might providing a new explanation for the regulation of T cell activation and potential new idea for autoimmune diseases and tumor immunotherapies.
Insights
Cbl-b normally inhibits T cell activation. Its absence increases miR-99a/miR-125b, leading to T cell over-activation. This study reveals Cbl-b targets SHP-2, impacting HOXA10 and microRNA regulation of T cell responses.
Area of Science:
- Immunology
- Molecular Biology
- Cellular Signaling
Background:
- T cell activation is crucial in immunity.
- Cbl-b's role in T cell inhibition is known, but its precise transcriptional regulatory mechanisms remain unclear.
- Understanding these pathways is vital for treating immune disorders.
Purpose of the Study:
- To elucidate the molecular mechanism by which Cbl-b regulates T cell activation, focusing on transcriptional regulation.
- To investigate the roles of microRNAs (miRNAs) and specific proteins in this pathway.
- To identify potential therapeutic targets for autoimmune diseases and cancer immunotherapy.
Main Methods:
- Gene ablation studies (Cbl-b knockout).
- miRNA expression analysis (miR-99a, miR-125b).
- Protein interaction and ubiquitination assays (SHP-2).
- Western blotting, luciferase reporter assays, CUT&Tag qPCR.
- T cell activation assays and pathway analysis (PI3K/AKT).
Main Results:
- Cbl-b deficiency led to increased miR-99a and miR-125b expression and T cell over-activation.
- Cbl-b targets and ubiquitinates SHP-2, a key regulator of T cell activation.
- SHP-2 dephosphorylates HOXA10, which translocates to the nucleus and regulates miR-99a/miR-125b expression.
- miR-99a/miR-125b were found to regulate the PI3K/AKT pathway, impacting T cell activation.
Conclusions:
- Cbl-b inhibits CD4+ T cell activation by ubiquitylation of SHP-2, thereby controlling HOXA10-mediated regulation of miR-99a/miR-125b.
- This pathway influences T cell activation via the PI3K/AKT signaling cascade.
- The findings offer new insights into T cell regulation and potential therapeutic strategies for immune-related diseases and cancer immunotherapy.
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