Untangling the role of RhoA in the heart: protective effect and mechanism.

RhoA (ras homolog family member A) is a small G-protein that transduces intracellular signaling to regulate a broad range of cellular functions such as cell growth, proliferation, migration, and survival. RhoA serves as a proximal downstream effector of numerous G protein-coupled receptors (GPCRs) and is also responsive to various stresses in the heart. Upon its activation, RhoA engages multiple downstream signaling pathways.

Gα12 signaling regulates transcriptional and phenotypic responses that promote glioblastoma tumor invasion.

In silico interrogation of glioblastoma (GBM) in The Cancer Genome Atlas (TCGA) revealed upregulation of GNA12 (Gα12), encoding the alpha subunit of the heterotrimeric G-protein G12, concomitant with overexpression of multiple G-protein coupled receptors (GPCRs) that signal through Gα12. Glioma stem cell lines from patient-derived xenografts also showed elevated levels of Gα12. Knockdown (KD) of Gα12 was carried out in two different human GBM stem cell (GSC) lines.

A gain-of-function p53 mutant synergizes with oncogenic NRAS to promote acute myeloid leukemia in mice.

We previously demonstrated that a subset of acute myeloid leukemia (AML) patients with concurrent RAS pathway and TP53 mutations have an extremely poor prognosis and that most of these TP53 mutations are missense mutations. Here, we report that, in contrast to the mixed AML and T cell malignancy that developed in NrasG12D/+ p53-/- (NP-/-) mice, NrasG12D/+ p53R172H/+ (NPmut) mice rapidly developed inflammation-associated AML. Under the inflammatory conditions, NPmut hematopoietic stem and progenitor cells (HSPCs) displayed imbalanced myelopoiesis and lymphopoiesis and mostly normal cell proliferation despite MEK/ERK hyperactivation.

HAPLN1 matrikine: a bone marrow homing factor linked to poor outcomes in patients with MM.

The bone marrow (BM) microenvironment is critical for dissemination, growth, and survival of multiple myeloma (MM) cells. Homing of myeloma cells to the BM niche is a crucial step in MM dissemination, but the mechanisms involved are incompletely understood. In particular, any role of matrikines, neofunctional peptides derived from extracellular matrix proteins, remains unknown.

Role of mitochondria-bound HK2 in rheumatoid arthritis fibroblast-like synoviocytes.

Background: Glucose metabolism, specifically, hexokinase 2 (HK2), has a critical role in rheumatoid arthritis (RA) fibroblast-like synoviocyte (FLS) phenotype. HK2 localizes not only in the cytosol but also in the mitochondria, where it protects mitochondria against stress. We hypothesize that mitochondria-bound HK2 is a key regulator of RA FLS phenotype.

Several Alphaherpesviruses Interact Similarly with the NF-κB Pathway and Suppress NF-κB-Dependent Gene Expression.

Alphaherpesvirus infection is associated with attenuation of different aspects of the host innate immune response that is elicited to confine primary infections at the mucosal epithelia. Here, we report that infection of epithelial cells with several alphaherpesviruses of different species, including herpes simplex virus 1 and 2 (HSV-1 and HSV-2), feline alphaherpesvirus 1 (FHV-1), and bovine alphaherpesvirus 1 (BoHV-1) results in the inactivation of the responses driven by the nuclear factor kappa B (NF-κB) pathway, considered a pillar of the innate immune response. The mode to interact with and circumvent NF-κB-driven responses in infected epithelial cells is seemingly conserved in human, feline, and porcine alphaherpesviruses, consisting of a persistent activation of the NF-κB cascade but a potent repression of NF-κB-dependent transcription activity, which relies on replication of viral genomes.

Ectopic CH60 mediates HAPLN1-induced cell survival signaling in multiple myeloma.

Multiple myeloma (MM), the second most common hematological malignancy, is generally considered incurable because of the development of drug resistance. We previously reported that hyaluronan and proteoglycan link protein 1 (HAPLN1) produced by stromal cells induces activation of NF-κB, a tumor-supportive transcription factor, and promotes drug resistance in MM cells. However, the identity of the cell surface receptor that detects HAPLN1 and thereby engenders pro-tumorigenic signaling in MM cells remains unknown.

HAPLN1 confers multiple myeloma cell resistance to several classes of therapeutic drugs.

Multiple myeloma (MM), a malignant plasma cell infiltration of the bone marrow, is generally considered incurable: resistance to multiple therapeutic drugs inevitably arises from tumor cell-intrinsic and tumor microenvironment (TME)-mediated mechanisms. Here we report that the proteoglycan tandem repeat 1 (PTR1) domain of the TME matrix protein, hyaluronan and proteoglycan link protein 1 (HAPLN1), induces a host of cell survival genes in MM cells and variable resistance to different classes of clinical drugs, including certain proteasome inhibitors, steroids, immunomodulatory drugs, and DNA damaging agents, in several MM cell lines tested. Collectively, our study identifies HAPLN1 as an extracellular matrix factor that can simultaneously confer MM cell resistance to multiple therapeutic drugs.

The SUMO protease SENP1 promotes aggressive behaviors of high HIF2α expressing renal cell carcinoma cells.

While an important role for the SUMO protease SENP1 is recognized in multiple solid cancers, its role in renal cell carcinoma (RCC) pathogenesis, particularly the most dominant subtype, clear cell RCC (ccRCC), is poorly understood. Here we show that a combination of high HIF2α and SENP1 expression in ccRCC samples predicts poor patient survival. Using ccRCC cell models that express high HIF2α but low SENP1, we show that overexpression of SENP1 reduces sumoylation and ubiquitination of HIF2α, increases HIF2α transcriptional activity, and enhances expression of genes associated with cancer cell invasion, stemness and epithelial-mesenchymal transition.

RHOA, a small G-protein, signals to mitophagy through regulation of PINK1 protein stability and protects cardiomyocytes against ischemia.

RHOA (ras homolog family member A) is a small G-protein that regulates a range of cellular processes including cell growth and survival. RHOA is a proximal downstream effector of G protein-coupled receptors coupling to GNA12/Gα-GNA13/Gα proteins, and is activated in response to stretch and oxidative stress, functioning as a stress-response molecule. It has been demonstrated that RHOA signaling provides cardioprotection through inhibition of mitochondrial death pathways.

RhoA signaling increases mitophagy and protects cardiomyocytes against ischemia by stabilizing PINK1 protein and recruiting Parkin to mitochondria.

Mitophagy, a mitochondria-specific form of autophagy, removes dysfunctional mitochondria and is hence an essential process contributing to mitochondrial quality control. PTEN-induced kinase 1 (PINK1) and the E3 ubiquitin ligase Parkin are critical molecules involved in stress-induced mitophagy, but the intracellular signaling mechanisms by which this pathway is regulated are unclear. We tested the hypothesis that signaling through RhoA, a small GTPase, induces mitophagy via modulation of the PINK1/Parkin pathway as a protective mechanism against ischemic stress.

Pseudorabies Virus Infection Results in a Broad Inhibition of Host Gene Transcription.

Pseudorabies virus (PRV) is a porcine alphaherpesvirus that belongs to the family. We showed earlier that infection of porcine epithelial cells with PRV triggers activation of the nuclear factor κB (NF-κB) pathway, a pivotal signaling axis in the early immune response. However, PRV-induced NF-κB activation does not lead to NF-κB-dependent gene expression.

Timelapse viability assay to detect division and death of primary multiple myeloma cells in response to drug treatments with single cell resolution.

Heterogeneity among cancer cells and in the tumor microenvironment (TME) is thought to be a significant contributor to the heterogeneity of clinical therapy response observed between patients and can evolve over time. A primary example of this is multiple myeloma (MM), a generally incurable cancer where such heterogeneity contributes to the persistent evolution of drug resistance. However, there is a paucity of functional assays for studying this heterogeneity in patient samples or for assessing the influence of the patient TME on therapy response.

A Hyaluronan and Proteoglycan Link Protein 1 Matrikine: Role of Matrix Metalloproteinase 2 in Multiple Myeloma NF-κB Activation and Drug Resistance.

Unlabelled: The NF-κB signaling pathway plays key roles in inflammation and the pathogenesis of many solid and hematologic malignancies, including multiple myeloma, a malignancy of the plasma cells. While proteasome inhibitors, such as bortezomib, employed in multiple myeloma treatments may inhibit NF-κB signaling pathways, multiple myeloma cells often become drug resistant in part due to non-cell autonomous mechanism(s) from the multiple myeloma tumor microenvironment. We previously found that fragments of, but not full-length, hyaluronan and proteoglycan link protein 1 (HAPLN1), produced by multiple myeloma bone marrow stromal cells (BMSC), activate an atypical bortezomib-resistant NF-κB pathway in multiple myeloma cells.

Molecular Signaling to Preserve Mitochondrial Integrity against Ischemic Stress in the Heart: Rescue or Remove Mitochondria in Danger.

Cardiovascular diseases are one of the leading causes of death and global health problems worldwide, and ischemic heart disease is the most common cause of heart failure (HF). The heart is a high-energy demanding organ, and myocardial energy reserves are limited. Mitochondria are the powerhouses of the cell, but under stress conditions, they become damaged, release necrotic and apoptotic factors, and contribute to cell death.

Analyze the SUMOylation of IKK γ/NEMO During Genotoxic Stress.

SUMOylation is an important posttranslational modification of substrate proteins that regulates their functions in a variety of cellular processes including epigenetic and transcriptional regulation of gene expression, genomic stability, DNA repair, subcellular translocation, and protein turnover. The critical roles of SUMOylation in regulating NF-κB signaling is exemplified by the findings that it regulates IκBα stability, transactivity of RelA and RelB, as well as initiating the export of nuclear DNA damage signal to cytoplasmic IKK complex through NEMO SUMOylation. Detection of SUMOylated protein is technically challenging due to only a small fraction of substrate proteins is SUMOylated and this process is also reversible by highly active SUMO-deconjugating enzymes.

ATPase Inhibitory Factor-1 Disrupts Mitochondrial Ca Handling and Promotes Pathological Cardiac Hypertrophy through CaMKIIδ.

ATPase inhibitory factor-1 (IF1) preserves cellular ATP under conditions of respiratory collapse, yet the function of IF1 under normal respiring conditions is unresolved. We tested the hypothesis that IF1 promotes mitochondrial dysfunction and pathological cardiomyocyte hypertrophy in the context of heart failure (HF). Methods and results: Cardiac expression of IF1 was increased in mice and in humans with HF, downstream of neurohumoral signaling pathways and in patterns that resembled the fetal-like gene program.

SiglecF(HI) Marks Late-Stage Neutrophils of the Infarcted Heart: A Single-Cell Transcriptomic Analysis of Neutrophil Diversification.

Background Neutrophils are thought to be short-lived first responders to tissue injuries such as myocardial infarction (MI), but little is known about their diversification or dynamics. Methods and Results We permanently ligated the left anterior descending coronary arteries of mice and performed single-cell RNA sequencing and analysis of >28 000 neutrophil transcriptomes isolated from the heart, peripheral blood, and bone marrow of mice on days 1 to 4 after MI or at steady-state. Unsupervised clustering of cardiac neutrophils revealed 5 major subsets, 3 of which originated in the bone marrow, including a late-emerging granulocyte expressing SiglecF, a marker classically used to define eosinophils.

Histamine-induced biphasic activation of RhoA allows for persistent RhoA signaling.

The small GTPase RhoA is a central signaling enzyme that is involved in various cellular processes such as cytoskeletal dynamics, transcription, and cell cycle progression. Many signal transduction pathways activate RhoA-for instance, Gαq-coupled Histamine 1 Receptor signaling via Gαq-dependent activation of RhoGEFs such as p63. Although multiple upstream regulators of RhoA have been identified, the temporal regulation of RhoA and the coordination of different upstream components in its regulation have not been well characterized.

IκBα Nuclear Export Enables 4-1BB-Induced cRel Activation and IL-2 Production to Promote CD8 T Cell Immunity.

Optimal CD8 T cell immunity is orchestrated by signaling events initiated by TCR recognition of peptide Ag in concert with signals from molecules such as CD28 and 4-1BB. The molecular mechanisms underlying the temporal and spatial signaling dynamics in CD8 T cells remain incompletely understood. In this study, we show that stimulation of naive CD8 T cells with agonistic CD3 and CD28 Abs, mimicking TCR and costimulatory signals, coordinately induces 4-1BB and cRel to enable elevated cytosolic cRel:IκBα complex formation and subsequent 4-1BB-induced IκBα degradation, sustained cRel activation, heightened IL-2 production and T cell expansion.