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Published on: January 10, 2025
Dicer cleavage by calpain determines platelet microRNA levels and function in diabetes
Amro Elgheznawy1, Lei Shi1, Jiong Hu1
1From the Institute for Vascular Signaling, Centre for Molecular Medicine, and DZHK (German Centre for Cardiovascular Research) partner site Rhine-Main, Frankfurt, Germany (A.E., L.S., J.H., H.L., V.R., I.F.); Functional Proteomics, SFB 815 Core Unit, Goethe-University, Frankfurt, Germany (I.W.); Walter-Brendel-Centre of Experimental Medicine and DZHK partner site Munich Heart Alliance, Ludwig-Maximilians-Universität, Munich, Germany (J.P.); Endokrinologikum Frankfurt, Frankfurt, Germany (A.M.); and Centre Hospitalier Universitaire de Québec Research Center, and Faculty of Medicine, Université Laval, Quebec, Canada (P.P.).
Rationale:
MicroRNAs (miRNAs) are short noncoding RNA species generated by the processing of longer precursors by the ribonucleases Drosha and Dicer. Platelets contain large amounts of miRNA that are altered by disease, in particular diabetes mellitus.
Objective:
This study determined why platelet miRNA levels are attenuated in diabetic individuals and how decreased levels of the platelet-enriched miRNA, miR-223, affect platelet function.
Methods And Results:
Dicer levels were altered in platelets from diabetic mice and patients, a change that could be attributed to the cleavage of the enzyme by calpain, resulting in loss of function. Diabetes mellitus in human subjects as well as in mice resulted in decreased levels of platelet miR-142, miR-143, miR-155, and miR-223. Focusing on only 1 of these miRNAs, miR-223 deletion in mice resulted in modestly enhanced platelet aggregation, the formation of large thrombi and delayed clot retraction compared with wild-type littermates. A similar dysregulation was detected in platelets from diabetic patients. Proteomic analysis of platelets from miR-223 knockout mice revealed increased levels of several proteins, including kindlin-3 and coagulation factor XIII-A. Whereas, kindlin-3 was indirectly regulated by miR-223, factor XIII was a direct target and both proteins were also altered in diabetic platelets. Treating diabetic mice with a calpain inhibitor prevented loss of platelet dicer as well as the diabetes mellitus-induced decrease in platelet miRNA levels and the upregulation of miR-223 target proteins.
Conclusions:
Thus, calpain inhibition may be one means of normalizing platelet miRNA processing as well as platelet function in diabetes mellitus.
Insights
Diabetes mellitus reduces platelet microRNA (miRNA) levels by altering Dicer processing via calpain. Restoring Dicer function with a calpain inhibitor normalized miRNA levels and improved platelet function in diabetic mice.
Area of Science:
- Biochemistry
- Molecular Biology
- Hematology
Background:
- MicroRNAs (miRNAs) are key regulators of gene expression.
- Platelets are rich in miRNAs, which are altered in disease states like diabetes mellitus.
- The ribonucleases Drosha and Dicer are essential for miRNA biogenesis.
Purpose of the Study:
- To investigate the mechanisms behind reduced platelet miRNA levels in diabetes.
- To determine the impact of decreased miR-223 levels on platelet function.
- To explore therapeutic strategies for normalizing platelet miRNA processing in diabetes.
Main Methods:
- Assessed Dicer levels and activity in platelets from diabetic and non-diabetic mice and patients.
- Utilized miR-223 knockout mice to study its role in platelet function.
- Performed proteomic analysis to identify miR-223 targets in platelets.
- Administered calpain inhibitors to diabetic mice to assess effects on Dicer, miRNA levels, and platelet function.
Main Results:
- Dicer cleavage by calpain reduced Dicer function and miRNA levels in diabetic platelets.
- Diabetes led to decreased levels of miR-142, miR-143, miR-155, and miR-223 in platelets.
- miR-223 deficiency enhanced platelet aggregation and thrombus formation.
- Coagulation factor XIII-A was identified as a direct target of miR-223 and was upregulated in diabetic platelets.
- Calpain inhibition restored Dicer function, normalized miRNA levels, and improved platelet function in diabetic mice.
Conclusions:
- Calpain-mediated Dicer cleavage contributes to miRNA dysregulation in diabetic platelets.
- Restoring platelet miRNA processing via calpain inhibition may normalize platelet function in diabetes mellitus.
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