MKL-1 is a coactivator for STAT5b, the regulator of Treg cell development and function

Rho-kinase inhibitor alleviates CD4+T cell mediated corneal graft rejection by modulating its STAT3 and STAT5 activation

Penetrating keratoplasty remains the most common treatment to restore vision for corneal diseases. Immune rejection after corneal transplantation is one of the major causes of graft failure. In recent years, Rho-associated protein kinase (ROCK) inhibitors have been found to be associated with the activation of the STATs pathway and are widely studied in autoimmune diseases. Therefore, it may be possible that the ROCK inhibitors also participate in the local and systemic immune regulation in corneal transplantation through activation of the STATs pathway and affect the CD4+ T cell differentiation. This study aimed to explore the role of ROCK-STATs pathway in the occurrence of immune rejection in corneal transplantation by applying Y27632, a ROCK inhibitor, to the recipient mice and peripheral CD4+ T cells. We found that Y27632 significantly up-regulated the phosphorylation level of STAT5 in both spleen and lymph nodes, down-regulated the phosphorylation level of STAT3 in the CD4+ T cells in the spleen. It also increased the proportion of CD4+CD25+Foxp3+Helios+ Tregs while decreased CD4+IL17A+ -Th17 cells. Moreover, Y27632 also reduced the proportion of dendritic cells in both spleen and lymph nodes, as well as the expression level of CD86 on their surfaces in the spleen, while the proportion of macrophages was not affected. The expression levels of ROCK1, ROCK2, CD11c and IL-17A mRNA were also found to be low in the graft tissue while the expression of Helios was upregulated. Rho-kinase inhibitor can modulate the balance of Tregs/Th17 by regulating the phosphorylation levels of both STAT3 and STAT5, thereby inhibiting the occurrence of immune rejection in allogeneic corneal transplantation.

MRTFA: A critical protein in normal and malignant hematopoiesis and beyond

Myocardin-related transcription factor A (MRTFA) is a coactivator of serum response factor, a transcription factor that participates in several critical cellular functions including cell growth and apoptosis. MRTFA couples transcriptional regulation to actin cytoskeleton dynamics, and the transcriptional targets of the MRTFA–serum response factor complex include genes encoding cytoskeletal proteins as well as immediate early genes. Previous work has shown that MRTFA promotes the differentiation of many cell types, including various types of muscle cells and hematopoietic cells, and MRTFA's interactions with other protein partners broaden its cellular roles. However, despite being first identified as part of the recurrent t(1;22) chromosomal translocation in acute megakaryoblastic leukemia, the mechanisms by which MRTFA functions in malignant hematopoiesis have yet to be defined. In this review, we provide an in-depth examination of the structure, regulation, and known functions of MRTFA with a focus on hematopoiesis. We conclude by identifying areas of study that merit further investigation.