hkb is required for DIP-α expression and target recognition in the Drosophila neuromuscular circuit.

Our nervous system contains billions of neurons that form precise connections with each other through interactions between cell surface proteins. In Drosophila, the Dpr and DIP immunoglobulin protein subfamilies form homophilic or heterophilic interactions to instruct synaptic connectivity, synaptic growth, and cell survival. However, the upstream regulatory mechanisms of Dprs and DIPs are not clear.

is required for expression and target recognition in the neuromuscular circuit.

Our nervous system contains billions of neurons that form precise connections with each other through interactions between cell surface proteins (CSPs). In , the Dpr and DIP immunoglobulin protein subfamilies form homophilic or heterophilic interactions to instruct synaptic connectivity, synaptic growth and cell survival. However, the upstream regulation and downstream signaling mechanisms of Dprs and DIPs are not clear.

Translational landscape of glioblastoma immunotherapy for physicians: guiding clinical practice with basic scientific evidence.

Despite recent advances in cancer therapeutics, glioblastoma (GBM) remains one of the most difficult cancers to treat in both the primary and recurrent settings. GBM presents a unique therapeutic challenge given the immune-privileged environment of the brain and the aggressive nature of the disease. Furthermore, it can change phenotypes throughout the course of disease-switching between mesenchymal, neural, and classic gene signatures, each with specific markers and mechanisms of resistance.

Thrombin contributes to cancer immune evasion via proteolysis of platelet-bound GARP to activate LTGF-β.

Cancer-associated thrombocytosis and high concentrations of circulating transforming growth factor-β1 (TGF-β1) are frequently observed in patients with progressive cancers. Using genetic and pharmacological approaches, we show a direct link between thrombin catalytic activity and release of mature TGF-β1 from platelets. We found that thrombin cleaves glycoprotein A repetitions predominant (GARP), a cell surface docking receptor for latent TGF-β1 (LTGF-β1) on platelets, resulting in liberation of active TGF-β1 from the GARP-LTGF-β1 complex.

Development of molecular and pharmacological switches for chimeric antigen receptor T cells.

The use of chimeric antigen receptor (CAR) T cell technology as a therapeutic strategy for the treatment blood-born human cancers has delivered outstanding clinical efficacy. However, this treatment modality can also be associated with serious adverse events in the form of cytokine release syndrome. While several avenues are being pursued to limit the off-target effects, it is critically important that any intervention strategy has minimal consequences on long term efficacy.

GARP Dampens Cancer Immunity by Sustaining Function and Accumulation of Regulatory T Cells in the Colon.

Activated regulatory T (Treg) cells express the surface receptor glycoprotein-A repetitions predominant (GARP), which binds and activates latent TGFβ. How GARP modulates Treg function in inflammation and cancer remains unclear. Here we demonstrate that loss of GARP in Treg cells leads to spontaneous inflammation with highly activated CD4 and CD8 T cells and development of enteritis.

B lymphocytes confer immune tolerance via cell surface GARP-TGF-β complex.

GARP, a cell surface docking receptor for binding and activating latent TGF-β, is highly expressed by platelets and activated Tregs. While GARP is implicated in immune invasion in cancer, the roles of the GARP-TGF-β axis in systemic autoimmune diseases are unknown. Although B cells do not express GARP at baseline, we found that the GARP-TGF-β complex is induced on activated human and mouse B cells by ligands for multiple TLRs, including TLR4, TLR7, and TLR9.

Immunoregulatory functions and the therapeutic implications of GARP-TGF-β in inflammation and cancer.

GARP (glycoprotein-A repetitions predominant) is a type I transmembrane cell surface docking receptor for latent transforming growth factor-β (TGF-β) that is abundantly expressed on regulatory T lymphocytes and platelets. GARP regulates the availability of membrane-bound latent TGF-β and modulates its activation. For this reason, GARP expression on immune and non-immune cells is involved in maintaining peripheral tolerance.

Glycoprotein A repetitions predominant (GARP) positively regulates transforming growth factor (TGF) β3 and is essential for mouse palatogenesis.

Glycoprotein A repetitions predominant (GARP) (encoded by the gene) plays important roles in cell-surface docking and activation of TGFβ. However, GARP's role in organ development in mammalian systems is unclear. To determine the function of GARP , we generated a GARP KO mouse model.

CNPY2 is a key initiator of the PERK-CHOP pathway of the unfolded protein response.

The unfolded protein response (UPR) in the endoplasmic reticulum (ER) is a highly conserved protein-quality-control mechanism critical for cells to make survival-or-death decisions under ER-stress conditions. However, how UPR sensors are activated remains unclear. Here, we report that ER luminal protein canopy homolog 2 (CNPY2) is released from grp78 upon ER stress.

Platelets subvert T cell immunity against cancer via GARP-TGFβ axis.

Cancer-associated thrombocytosis has long been linked to poor clinical outcome, but the underlying mechanism is enigmatic. We hypothesized that platelets promote malignancy and resistance to therapy by dampening host immunity. We show that genetic targeting of platelets enhances adoptive T cell therapy of cancer.

Structure of human nSMase2 reveals an interdomain allosteric activation mechanism for ceramide generation.

Neutral sphingomyelinase 2 (nSMase2, product of the gene) is a key enzyme for ceramide generation that is involved in regulating cellular stress responses and exosome-mediated intercellular communication. nSMase2 is activated by diverse stimuli, including the anionic phospholipid phosphatidylserine. Phosphatidylserine binds to an integral-membrane N-terminal domain (NTD); however, how the NTD activates the C-terminal catalytic domain is unclear.

Surface Expression of TGFβ Docking Receptor GARP Promotes Oncogenesis and Immune Tolerance in Breast Cancer.

GARP encoded by the Lrrc32 gene is the cell surface docking receptor for latent TGFβ, which is expressed naturally by platelets and regulatory T cells (Treg). Although Lrrc32 is amplified frequently in breast cancer, the expression and relevant functions of GARP in cancer have not been explored. Here, we report that GARP exerts oncogenic effects, promoting immune tolerance by enriching and activating latent TGFβ in the tumor microenvironment.

Role of neutral ceramidase in colon cancer.

Alterations in sphingolipid metabolism, especially ceramide and sphingosine 1-phosphate, have been linked to colon cancer, suggesting that enzymes of sphingolipid metabolism may emerge as novel regulators and targets in colon cancer. Neutral ceramidase (nCDase), a key enzyme in sphingolipid metabolism that hydrolyzes ceramide into sphingosine, is highly expressed in the intestine; however, its role in colon cancer has not been defined. Here we show that molecular and pharmacological inhibition of nCDase in colon cancer cells increases ceramide, and this is accompanied by decreased cell survival and increased apoptosis and autophagy, with minimal effects on noncancerous cells.

Suppression of Acid Sphingomyelinase Protects the Retina from Ischemic Injury.

Purpose: Acid sphingomyelinase (ASMase) catalyzes the hydrolysis of sphingomyelin to ceramide and mediates multiple responses involved in inflammatory and apoptotic signaling. However, the role ASMase plays in ischemic retinal injury has not been investigated. The purpose of this study was to investigate how reduced ASMase expression impacts retinal ischemic injury.

Clients and Oncogenic Roles of Molecular Chaperone gp96/grp94.

As an endoplasmic reticulum heat shock protein (HSP) 90 paralogue, glycoprotein (gp) 96 possesses immunological properties by chaperoning antigenic peptides for activation of T cells. Genetic studies in the last decade have unveiled that gp96 is also an essential master chaperone for multiple receptors and secreting proteins including Toll-like receptors (TLRs), integrins, the Wnt coreceptor, Low Density Lipoprotein Receptor-Related Protein 6 (LRP6), the latent TGFβ docking receptor, Glycoprotein A Repetitions Predominant (GARP), Glycoprotein (GP) Ib and insulin-like growth factors (IGF). Clinically, elevated expression of gp96 in a variety of cancers correlates with the advanced stage and poor survival of cancer patients.

GRP94/gp96 in Cancer: Biology, Structure, Immunology, and Drug Development.

As an endoplasmic reticulum heat-shock protein 90 (HSP90) paralog, GRP94 (glucose-regulated protein 94)/gp96 (hereafter referred to as GRP94) has been shown to be an essential master chaperone for multiple receptors including Toll-like receptors, Wnt coreceptors, and integrins. Clinically, expression of GRP94 correlates with advanced stage and poor survival in a variety of cancers. Recent preclinical studies have also revealed that GRP94 expression is closely linked to cancer growth and metastasis in melanoma, ovarian cancer, multiple myeloma, lung cancer, and inflammation-associated colon cancer.

Lack of Acid Sphingomyelinase Induces Age-Related Retinal Degeneration.

Background: Mutations of acid sphingomyelinase (ASMase) cause Niemann-Pick diseases type A and B, which are fatal inherited lipid lysosomal storage diseases, characterized with visceral organ abnormalities and neurodegeneration. However, the effects of suppressing retinal ASMase expression are not understood. The goal of this study was to determine if the disruption of ASMase expression impacts the retinal structure and function in the mouse, and begin to investigate the mechanisms underlying these abnormalities.

GP96 is a GARP chaperone and controls regulatory T cell functions.

Molecular chaperones control a multitude of cellular functions via folding chaperone-specific client proteins. CD4+FOXP3+ Tregs play key roles in maintaining peripheral tolerance, which is subject to regulation by multiple molecular switches, including mTOR and hypoxia-inducible factor. It is not clear whether GP96 (also known as GRP94), which is a master TLR and integrin chaperone, controls Treg function.

Endoplasmic reticulum heat shock protein gp96 maintains liver homeostasis and promotes hepatocellular carcinogenesis.

Background & Aims: gp96, or grp94, is an endoplasmic reticulum (ER)-localized heat shock protein 90 paralog that acts as a protein chaperone and plays an important role for example in ER homeostasis, ER stress, Wnt and integrin signaling, and calcium homeostasis, which are vital processes in oncogenesis. However, the cancer-intrinsic function of gp96 remains controversial.

Methods: We studied the roles of gp96 in liver biology in mice via an Albumin promoter-driven Cre recombinase-mediated disruption of gp96 gene, hsp90b1.

Targeting (cellular) lysosomal acid ceramidase by B13: design, synthesis and evaluation of novel DMG-B13 ester prodrugs.

Acid ceramidase (ACDase) is being recognized as a therapeutic target for cancer. B13 represents a moderate inhibitor of ACDase. The present study concentrates on the lysosomal targeting of B13 via its N,N-dimethylglycine (DMG) esters (DMG-B13 prodrugs).

Defining a role for acid sphingomyelinase in the p38/interleukin-6 pathway.

Acid sphingomyelinase (ASM) is one of the key enzymes involved in regulating the metabolism of the bioactive sphingolipid ceramide in the sphingolipid salvage pathway, yet defining signaling pathways by which ASM exerts its effects has proven difficult. Previous literature has implicated sphingolipids in the regulation of cytokines such as interleukin-6 (IL-6), but the specific sphingolipid pathways and mechanisms involved in inflammatory signaling need to be further elucidated. In this work, we sought to define the role of ASM in IL-6 production because our previous work showed that a parallel pathway of ceramide metabolism, acid β-glucosidase 1, negatively regulates IL-6.

Molecular regulation of macrophages in unleashing cancer-related inflammation.

It is unclear how tumor-associated macrophages (TAMs) contribute to the initiation of oncogenesis and how they are regulated at the molecular level. By using a lineage-specific deletion strategy, we found that heat shock protein 90kDa β (Grp94), member 1 (HSP90B1), a master chaperone for Toll-like receptors and integrins also known as GP96, critically endows TAMs with the ability to promote genotoxic stress and colitis-associated colon cancer.

Radiation-induced acid ceramidase confers prostate cancer resistance and tumor relapse.

Escape of prostate cancer (PCa) cells from ionizing radiation-induced (IR-induced) killing leads to disease progression and cancer relapse. The influence of sphingolipids, such as ceramide and its metabolite sphingosine 1-phosphate, on signal transduction pathways under cell stress is important to survival adaptation responses. In this study, we demonstrate that ceramide-deacylating enzyme acid ceramidase (AC) was preferentially upregulated in irradiated PCa cells.