Project description:Suspension-induced cell death, or anoikis, is implicated in different stages of breast development as well as tumor progression and metastasis. The pro-apoptotic BH3-only proteins BIM and BMF are known positive regulators of anoikis. We examined the gene expression changes that occur in BIM-/- BMF-/- cells during attachment and suspension. This study is supplemental to our work establishing a role for JNK in anoikis (Girnius N, Davis RJ. 2017. JNK promotes epithelial cell anoikis by transcriptional and post-translational regulation of BH3-only proteins. (2017) Cell Reports 21: 1910-1921; doi: 10.1016/j.celrep.2017.10.067)
Project description:Involution returns the lactating mammary gland to a quiescent state after weaning. The mechanism of involution involves collapse of the mammary epithelial cell compartment. To test whether the cJUN NH2-terminal kinase (JNK) signal transduction pathway contributes to involution, we established mice with JNK deficiency in the mammary epithelium. We found that JNK is required for efficient involution. JNK deficiency did not alter the STAT3/5 or SMAD2/3 signaling pathways that have been previously implicated in this process. Nevertheless, JNK promotes the expression of genes that drive involution, including matrix metalloproteases, cathepsins, and BH3-only proteins. These data demonstrate that JNK has a key role in mammary gland involution post lactation.
Project description:Developmental morphogenesis, tissue injury, and oncogenic transformation can cause the detachment of epithelial cells. These cells are eliminated by a specialized form of apoptosis (anoikis). While the processes that contribute to this form of cell death have been studied, the underlying mechanisms remain unclear. Here we tested the role of the cJUN NH2-terminal kinase (JNK) signaling pathway using murine models with compound JNK-deficiency in mammary and kidney epithelial cells. These studies demonstrated that JNK is required for efficient anoikis in vitro and in vivo. Moreover, JNK-promoted anoikis required pro-apoptotic members of the BCL2 family of proteins. We show that JNK acts through a BAK/BAX-dependent apoptotic pathway by increasing BIM expression and phosphorylating BMF leading to death of detached epithelial cells.
Project description:Both mRNA and proteins can be modified through addition of methyl groups. For example, addition of N6-methyladenosine (m6A) to mRNAs is critical for human development and health. Post-translational methylation of proteins can impact the dynamic regulation of enzymatic activity. Here we sought to explore the nexus of transcriptional and post-translational methylation by studying the role of methylation of the core methyltransferase METTL3/METTL14 in m6A regulation. We found by mass spectrometry that METTL14 arginine 255 (R255) is methylated (R255me). Global mRNA m6A levels were greatly decreased in METTL14 R255K mutant mouse embryonic stem cells (mESCs). We further found that R255me greatly enhances the interaction of METTL3/METTL14 with WTAP and promotes the binding of the complex to substrate RNA.
Project description:TP53-mutant blood cancers remain a major clinical challenge. BH3-mimetic drugs inhibit BCL-2 pro-survival proteins to promote cancer cell apoptosis. Despite acting downstream of TP53, functional TP53 is required for maximal cancer cell killing by BH3-mimetics through an unknown mechanism. Here, we report TP53 can be activated following BH3-mimetic induced mitochondrial outer membrane permeabilization, which leads to induction of BH3-only proteins, thereby potentiating the pro-apoptotic signal. TP53-deficient lymphomas lack this feed-forward loop, providing opportunities for survival and disease relapse after BH3-mimetic treatment. The therapeutic barrier imposed by defects in TP53 could be overcome by direct activation of the cGAS/STING pathway, which promotes apoptosis of blood cancer cells through TP53-independent BH3-only protein upregulation. Combining clinically relevant STING agonists with BH3-mimetics efficiently killed TP53-mutant mouse B lymphoma, human NK/T lymphoma and acute myeloid leukemia cells. This represents a promising therapy regime that can be fast-tracked to tackle TP53-mutant blood cancers in the clinic.
Project description:BMP9 promotes anoikis sensitivity in cancer cell lines. Here we examine the changes in gene expression in response to BMP9 in cells under anoikis to identify potential pathways associated with anoikis sensitivity.
