A role for MKP3 in axial patterning of the zebrafish embryo. Tsang Michael,Maegawa Shingo,Kiang Anne,Habas Raymond,Weinberg Eric,Dawid Igor B Development (Cambridge, England) Fibroblast growth factors (FGFs) are secreted molecules that can activate the RAS/mitogen-activated protein kinase (MAPK) pathway to serve crucial functions during embryogenesis. Through an in situ hybridization screen for genes with restricted expression patterns during early zebrafish development, we identified a group of genes that exhibit similar expression patterns to FGF genes. We report the characterization of zebrafish MAP kinase phosphatase 3 (MKP3; DUSP6 - Zebrafish Information Network), a member of the FGF synexpression group, showing that it has a crucial role in the specification of axial polarity in the early zebrafish embryo. MKP3 dephosphorylates the activated form of MAPK, inhibiting the RAS/MAPK arm of the FGF signaling pathway. Gain- and loss-of-function studies reveal that MKP3 is required to limit the extent of FGF/RAS/MAPK signaling in the early embryo, and that disturbing this inhibitory pathway disrupts dorsoventral patterning at the onset of gastrulation. The earliest mkp3 expression is restricted to the future dorsal region of the embryo where it is initiated by a maternal beta-catenin signal, but soon after its initiation, mkp3 expression comes under the control of FGF signaling. Thus, mkp3 encodes a feedback attenuator of the FGF pathway, the expression of which is initiated at an early stage so as to ensure correct FGF signaling levels at the time of axial patterning. 10.1242/dev.01157

Characterization of a Distinct State in the Continuum of Pluripotency Facilitated by Inhibition of PKCζ in Mouse Embryonic Stem Cells. Stem cell reviews and reports Inhibition of PKC (PKCi) signaling maintains pluripotency of embryonic stem cells (ESCs) across different mammalian species. However, the position of PKCi maintained ESCs in the pluripotency continuum is largely unknown. Here we demonstrate that mouse ESCs when cultured continuously, with PKCi, for 75 days are retained in naïve state of pluripotency. Gene expression analysis and proteomics studies demonstrated enhanced naïve character of PKCi maintained ESCs in comparison to classical serum/LIF (S/L) supported ESCs. Molecular analysis revealed that activation of PKCζ isoform associate with primed state of pluripotency, present in epiblast-like stem cells generated in vitro while inhibition of PKCζ phosphorylation associated with naïve state of pluripotency in vitro and in vivo. Phosphoproteomics and chromatin modification enzyme array based studies showed loss in DNA methyl transferase 3B (DNMT3B) and its phosphorylation level upon functional inhibition of PKCζ as one of the crucial components of this regulatory pathway. Unlike ground state of pluripotency maintained by MEK/GSK3 inhibitor in addition to LIF (2i/LIF), loss in DNMT3B is a reversible phenomenon in PKCi maintained ESCs. Absence of phosphorylation of c-MYC, RAF1, SPRY4 while presence of ERF, DUSP6, CIC and YAP1 phosphorylation underlined the phosphoproteomics signature of PKCi mediated maintenance of naïve pluripotency. States of pluripotency represent the developmental continuum and the existence of PKCi mediated mouse ESCs in a distinct state in the continuum of pluripotency (DiSCo) might contribute to the establishment of stages of murine embryonic development that were non-permissible till date. 10.1007/s12015-023-10513-5

Acute Endoplasmic Reticulum Stress Suppresses Hepatic Gluconeogenesis by Stimulating MAPK Phosphatase 3 Degradation. International journal of molecular sciences Drug-induced liver injury (DILI) is a widespread and harmful disease, and is closely linked to acute endoplasmic reticulum (ER) stress. Previous reports have shown that acute ER stress can suppress hepatic gluconeogenesis and even leads to hypoglycemia. However, the mechanism is still unclear. MAPK phosphatase 3 (MKP-3) is a positive regulator for gluconeogenesis. Thus, this study was conducted to investigate the role of MKP-3 in the suppression of gluconeogenesis by acute ER stress, as well as the regulatory role of acute ER stress on the expression of MKP-3. Results showed that acute ER stress induced by tunicamycin significantly suppressed gluconeogenesis in both hepatocytes and mouse liver, reduced glucose production level in hepatocytes, and decreased fasting blood glucose level in mice. Additionally, the protein level of MKP-3 was reduced by acute ER stress in both hepatocytes and mouse liver. deficiency eliminated the inhibitory effect of acute ER stress on gluconeogenesis in hepatocytes. Moreover, the reduction effect of acute ER stress on blood glucose level and hepatic glucose 6-phosphatase () expression was not observed in the liver-specific knockout mice. Furthermore, activation of protein kinase R-like ER kinase (PERK) decreased the MKP-3 protein level, while inactivation of PERK abolished the reduction effect of acute ER stress on the MKP-3 protein level in hepatocytes. Taken together, our study suggested that acute ER stress could suppress hepatic gluconeogenesis by stimulating MKP-3 degradation via PERK, at least partially. Thus, MKP-3 might be a therapeutic target for DILI-related hypoglycemia. 10.3390/ijms242115561