Ectodomain shedding and ADAMs in development

New insights into the function and pathophysiology of the ectodomain sheddase A Disintegrin And Metalloproteinase 10 (ADAM10)

The 'A Disintegrin And Metalloproteinase 10' (ADAM10) has gained considerable attention due to its discovery as an 'α-secretase' involved in the nonamyloidogenic processing of the amyloid precursor protein, thereby possibly preventing the excessive generation of the amyloid beta peptide, which is associated with the pathogenesis of Alzheimer's disease. ADAM10 was found to exert many additional functions, cleaving about 100 different membrane proteins. ADAM10 is involved in many pathophysiological conditions, ranging from cancer and autoimmune disorders to neurodegeneration and inflammation. ADAM10 cleaves its substrates close to the plasma membrane, a process referred to as ectodomain shedding. This is a central step in the modulation of the functions of cell adhesion proteins and cell surface receptors. ADAM10 activity is controlled by transcriptional and post-translational events. The interaction of ADAM10 with tetraspanins and the way they functionally and structurally depend on each other is another topic of interest. In this review, we will summarize findings on how ADAM10 is regulated and what is known about the biology of the protease. We will focus on novel aspects of the molecular biology and pathophysiology of ADAM10 that were previously poorly covered, such as the role of ADAM10 on extracellular vesicles, its contribution to virus entry, and its involvement in cardiac disease, cancer, inflammation, and immune regulation. ADAM10 has emerged as a regulator controlling cell surface proteins during development and in adult life. Its involvement in disease states suggests that ADAM10 may be exploited as a therapeutic target to treat conditions associated with a dysfunctional proteolytic activity.

Neratinib could be effective as monotherapy or in combination with trastuzumab in HER2-low breast cancer cells and organoid models

BACKGROUND

Previous studies have suggested that patients with HER2-low breast cancers do not benefit from trastuzumab treatment although the reasons remain unclear.

METHODS

We investigated the effect of trastuzumab monotherapy and its combination with different HER2 targeting treatments in a panel of breast cancer cell lines and patient-derived organoids (PDOs) using biochemical methods and cell viability assays.

RESULTS

Compared to sensitive HER2 over-expressing (IHC3 + ) breast cancer cells, increasing doses of trastuzumab could not achieve IC50 in MDA-MB-361 (IHC 2 + FISH + ) and MDA-MB-453 (IHC 2 + FISH-) cells which showed an intermediate response to trastuzumab. Trastuzumab treatment induced upregulation of HER ligand release, resulting in the activation of HER receptors in these cells, which could account for their trastuzumab insensitivity. Adding a dual ADAM10/17 inhibitor to inhibit the shedding of HER ligands in combination with trastuzumab only showed a modest decrease in the cell viability of HER2-low breast cancer cells and PDOs. However, the panHER inhibitor neratinib was an effective monotherapy in HER2-low breast cancer cells and PDOs, and showed additive effects when combined with trastuzumab.

CONCLUSION

This study demonstrates that neratinib in combination with trastuzumab may be effective in a subset of HER2-low breast cancers although further validation is required in a larger panel of PDOs and in future clinical studies.

Role of the prefrontal cortical protease TACE/ADAM17 in neurobehavioral responses to chronic stress during adolescence

INTRODUCTION

Chronic adolescent stress profoundly affects prefrontal cortical networks regulating top-down behavior control. However, the neurobiological pathways contributing to stress-induced alterations in the brain and behavior remain largely unknown. Chronic stress influences brain growth factors and immune responses, which may, in turn, disrupt the maturation and function of prefrontal cortical networks. The tumor necrosis factor alpha-converting enzyme/a disintegrin and metalloproteinase 17 (TACE/ADAM17) is a sheddase with essential functions in brain maturation, behavior, and inflammatory responses. This study aimed to determine the impact of stress on the prefrontal cortex and whether TACE/ADAM17 plays a role in these responses.

METHODS

We used a Lewis rat model that incorporates critical elements of chronic psychosocial stress, such as uncontrollability, unpredictability, lack of social support, and re-experiencing of trauma.

RESULTS

Chronic stress during adolescence reduced the acoustic startle reflex and social interactions while increasing extracellular free water content and TACE/ADAM17 mRNA levels in the medial prefrontal cortex. Chronic stress altered various ethological behavioral domains in the observation home cages (decreased ingestive behaviors and increased walking, grooming, and rearing behaviors). A group of rats was injected intracerebrally either with a novel Accell™ SMARTpool TACE/ADAM17 siRNA or a corresponding siRNA vehicle (control). The RNAscope Multiplex Fluorescent v2 Assay was used to visualize mRNA expression. Automated puncta quantification and analyses demonstrated that TACE/ADAM17 siRNA administration reduced TACE/ADAM17 mRNA levels in the medial prefrontal cortex (59% reduction relative to control). We found that the rats that received prefrontal cortical TACE/ADAM17 siRNA administration exhibited altered eating patterns (e.g., increased food intake and time in the feeding zone during the light cycle).

CONCLUSION

This study supports that the prefrontal cortex is sensitive to adolescent chronic stress and suggests that TACE/ADAM17 may be involved in the brain responses to stress.

A Disintegrin and metalloproteinase carves T cell abnormalities and pathogenesis in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a complex autoimmune disorder impacting various organs, notably prevalent in women of reproductive age. This review explores the involvement of a disintegrin and metalloproteinases (ADAMs) in SLE pathogenesis. Despite advancements in understanding SLE through genome and transcriptome studies, the role of ADAMs in post-translational regulations remains insufficiently explored. ADAMs, transmembrane proteins with diverse functions, impact cell adhesion, migration, and inflammation by shedding cell surface proteins, growth factors, and receptors. Notably, ADAM9 is implicated in Th17 cell differentiation, which is crucial in SLE pathology. ADAM10 and ADAM17 play pivotal roles in T-cell biology, influencing immune cell development and differentiation. Elevated soluble ADAM substrates in SLE patients serve as potential biomarkers correlating with disease activity. Targeting ADAMs or their substrates offers promising therapeutic avenues for SLE management and treatment enhancement.

Glycosaminoglycan modifications of betaglycan regulate ectodomain shedding to fine-tune TGF-β signaling responses in ovarian cancer

In pathologies including cancer, aberrant Transforming Growth Factor-β (TGF-β) signaling exerts profound tumor intrinsic and extrinsic consequences. Intense clinical endeavors are underway to target this pathway. Central to the success of these interventions is pinpointing factors that decisively modulate the TGF-β responses. Betaglycan/type III TGF-β receptor (TβRIII), is an established co-receptor for the TGF-β superfamily known to bind directly to TGF-βs 1-3 and inhibin A/B. Betaglycan can be membrane-bound and also undergo ectodomain cleavage to produce soluble-betaglycan that can sequester its ligands. Its extracellular domain undergoes heparan sulfate and chondroitin sulfate glycosaminoglycan modifications, transforming betaglycan into a proteoglycan. We report the unexpected discovery that the heparan sulfate glycosaminoglycan chains on betaglycan are critical for the ectodomain shedding. In the absence of such glycosaminoglycan chains betaglycan is not shed, a feature indispensable for the ability of betaglycan to suppress TGF-β signaling and the cells' responses to exogenous TGF-β ligands. Using unbiased transcriptomics, we identified TIMP3 as a key inhibitor of betaglycan shedding thereby influencing TGF-β signaling. Our results bear significant clinical relevance as modified betaglycan is present in the ascites of patients with ovarian cancer and can serve as a marker for predicting patient outcomes and TGF-β signaling responses. These studies are the first to demonstrate a unique reliance on the glycosaminoglycan chains of betaglycan for shedding and influence on TGF-β signaling responses. Dysregulated shedding of TGF-β receptors plays a vital role in determining the response and availability of TGF-βs', which is crucial for prognostic predictions and understanding of TGF-β signaling dynamics.

Mechanism of action and therapeutic targeting of CD30 molecule in lymphomas

At present, the treatment of lymphoma has entered the era of precision medicine, and CD30, as a transmembrane protein, has become an important marker to help the diagnosis and formulation of treatment plans for lymphomas. This protein is widely expressed in various types of lymphomas and can play a role through nuclear factor-κB (NF-κB), mitogen-activated protein kinase (MAPK), and other pathways, and ultimately lead to the up-regulation of CD30 expression to give tumor cells a survival advantage. Brentuximab vedotin (BV), as an antibody-drug conjugate (ADC) targeting CD30, is one of the first new drugs to significantly improve survival in patients with CD30+lymphomas. However, the biological function of CD30 has not been fully elucidated. Therefore, this review highlights the CD30-mediated tumor-promoting mechanisms and the molecular factors that regulate CD30 expression. We hope that a better understanding of CD30 biology will provide new insights into clinical treatment and improve the survival and quality of life of lymphoma patients.

Insights into the Tumor Microenvironment-Components, Functions and Therapeutics

Similarly to our healthy organs, the tumor tissue also constitutes an ecosystem. This implies that stromal cells acquire an altered phenotype in tandem with tumor cells, thereby promoting tumor survival. Cancer cells are fueled by abnormal blood vessels, allowing them to develop and proliferate. Tumor-associated fibroblasts adapt their cytokine and chemokine production to the needs of tumor cells and alter the peritumoral stroma by generating more collagen, thereby stiffening the matrix; these processes promote epithelial-mesenchymal transition and tumor cell invasion. Chronic inflammation and the mobilization of pro-tumorigenic inflammatory cells further facilitate tumor expansion. All of these events can impede the effective administration of tumor treatment; so, the successful inhibition of tumorous matrix remodeling could further enhance the success of antitumor therapy. Over the last decade, significant progress has been made with the introduction of novel immunotherapy that targets the inhibitory mechanisms of T cell activation. However, extensive research is also being conducted on the stromal components and other cell types of the tumor microenvironment (TME) that may serve as potential therapeutic targets.

The γ-secretase substrate proteome and its role in cell signaling regulation

γ-Secretases mediate the regulated intramembrane proteolysis (RIP) of more than 150 integral membrane proteins. We developed an unbiased γ-secretase substrate identification (G-SECSI) method to study to what extent these proteins are processed in parallel. We demonstrate here parallel processing of at least 85 membrane proteins in human microglia in steady-state cell culture conditions. Pharmacological inhibition of γ-secretase caused substantial changes of human microglial transcriptomes, including the expression of genes related to the disease-associated microglia (DAM) response described in Alzheimer disease (AD). While the overall effects of γ-secretase deficiency on transcriptomic cell states remained limited in control conditions, exposure of mouse microglia to AD-inducing amyloid plaques strongly blocked their capacity to mount this putatively protective DAM cell state. We conclude that γ-secretase serves as a critical signaling hub integrating the effects of multiple extracellular stimuli into the overall transcriptome of the cell.

Initial study of the detection of ADAM 10 in the urine of type-2 diabetic patients

Diabetes mellitus (DM) is a disease of civilization. If left untreated, it can cause serious complications and significantly shortens the life time. DM is one of the leading causes of end-stage renal disease (uremia) worldwide. Early diagnosis is a prerequisite for successful treatment, preferably before the first symptoms appear. In this paper, we describe the optimization and synthesis of the internally quenched fluorescent substrate disintegrin and metalloproteinase 10 (ADAM10). Using combinatorial chemistry methods with iterative deconvolution, the substrate specificity of the enzyme in non-primed and primed positions was determined. We used the ABZ-Lys-Ile-Ile-Asn-Leu-Lys-Arg-Tyr(3-NO2)-NH2 peptide to study ADAM10 activity in urine samples collected from patients diagnosed with type 2 diabetes, compared to urine samples from healthy volunteers. The proteolytically active enzyme was present in diabetes samples, while in the case of healthy people we did not observe any activity. In conclusion, our study provides a possible basis for further research into the potential role of ADAM10 in the diagnosis of type 2 diabetes.

Heparan sulfate modifications of betaglycan promote TIMP3-dependent ectodomain shedding to fine-tune TGF-β signaling

In pathologies such as cancer, aberrant Transforming Growth Factor-β (TGF-β) signaling exerts profound tumor intrinsic and extrinsic consequences. Intense clinical endeavors are underway to target this pivotal pathway. Central to the success of these interventions is pinpointing factors that decisively modulate the TGF-β responses. Betaglycan/type III TGF-β receptor (TβRIII), is an established co-receptor for the TGF-β superfamily known to bind directly to TGF-βs 1-3 and inhibin A/B. While betaglycan can be membrane-bound, it can also undergo ectodomain cleavage to produce soluble-betaglycan that can sequester its ligands. The extracellular domain of betaglycan undergoes heparan sulfate and chondroitin sulfate glycosaminoglycan modifications, transforming betaglycan into a proteoglycan. Here we report the unexpected discovery that the heparan sulfate modifications are critical for the ectodomain shedding of betaglycan. In the absence of such modifications, betaglycan is not shed. Such shedding is indispensable for the ability of betaglycan to suppress TGF-β signaling and the cells' responses to exogenous TGF-β ligands. Using unbiased transcriptomics, we identified TIMP3 as a key regulator of betaglycan shedding and thereby TGF-β signaling. Our results bear significant clinical relevance as modified betaglycan is present in the ascites of patients with ovarian cancer and can serve as a marker for predicting patient outcomes and TGF-β signaling responses. These studies are the first to demonstrate a unique reliance on the glycosaminoglycan modifications of betaglycan for shedding and influence on TGF-β signaling responses. Dysregulated shedding of TGF-β receptors plays a vital role in determining the response and availability of TGF-βs', which is crucial for prognostic predictions and understanding of TGF-β signaling dynamics.

SheddomeDB 2023: A Revision of an Ectodomain Shedding Database Based on a Comprehensive Literature Review and Online Resources

Ectodomain shedding of membrane proteins is a proteolytic event involved in several biological phenomena, including inflammation, development, diseases, and cancer progression. Though ectodomain shedding is a post-translational modification that plays an important role in cellular regulation, this biological phenomenon is seriously underannotated in public protein databases. Given the importance of the shedding events, we conducted a comprehensive literature review for membrane protein shedding and constructed the database, SheddomeDB in 2017. In response to user feedback, novel shedding findings, more associated biomedical events, and the advance in web technology, we revised SheddomeDB to a new version, SheddomeDB 2023. The revised SheddomeDB 2023 includes 481 protein entries across seven species; all the content was manually verified and curated. The content of SheddomeDB 2023 mainly came from a comprehensive literature survey by our newly developed semiautomated screening tool. We also integrated verified and updated cleavage and secretome information from other databases into the revision. In addition, SheddomeDB 2023 features a graphical presentation of cleavage information and a user-friendly interface for searching and browsing entries in the database. This revised comprehensive database of ectodomain shedding is expected to benefit biomedical researchers across different disciplines.

Exploring the Vital Link Between Glioma, Neuron, and Neural Activity in the Context of Invasion

Because of their ability to infiltrate normal brain tissue, gliomas frequently evade microscopic surgical excision. The histologic infiltrative property of human glioma has been previously characterized as Scherer secondary structures, of which the perivascular satellitosis is a prospective target for anti-angiogenic treatment in high-grade gliomas. However, the mechanisms underlying perineuronal satellitosis remain unclear, and therapy remains lacking. Our knowledge of the mechanism underlying Scherer secondary structures has improved over time. New techniques, such as laser capture microdissection and optogenetic stimulation, have advanced our understanding of glioma invasion mechanisms. Although laser capture microdissection is a useful tool for studying gliomas that infiltrate the normal brain microenvironment, optogenetics and mouse xenograft glioma models have been extensively used in studies demonstrating the unique role of synaptogenesis in glioma proliferation and identification of potential therapeutic targets. Moreover, a rare glioma cell line is established that, when transplanted in the mouse brain, can replicate and recapitulate the human diffuse invasion phenotype. This review discusses the primary molecular causes of glioma, its histopathology-based invasive mechanisms, and the importance of neuronal activity and interactions between glioma cells and neurons in the brain microenvironment. It also explores current methods and models of gliomas.

ADAM10-a "multitasker" in sepsis: focus on its posttranslational target

BACKGROUND

Sepsis has a complex pathogenesis in which the uncontrolled systemic inflammatory response triggered by infection leads to vascular barrier disruption, microcirculation dysfunction and multiple organ dysfunction syndrome. Numerous recent studies reveal that a disintegrin and metalloproteinase 10 (ADAM10) acts as a "molecular scissor" playing a pivotal role in the inflammatory response during sepsis by regulating proteolysis by cleaving various membrane protein substrates, including proinflammatory cytokines, cadherins and Notch, which are involved in intercellular communication. ADAM10 can also act as the cellular receptor for Staphylococcus aureus α-toxin, leading to lethal sepsis. However, its substrate-specific modulation and precise targets in sepsis have not yet to be elucidated.

METHODS

We performed a computer-based online search using PubMed and Google Scholar for published articles concerning ADAM10 and sepsis.

CONCLUSIONS

In this review, we focus on the functions of ADAM10 in sepsis-related complex endothelium-immune cell interactions and microcirculation dysfunction through the diversity of its substrates and its enzymatic activity. In addition, we highlight the posttranslational mechanisms of ADAM10 at specific subcellular sites, or in multimolecular complexes, which will provide the insight to intervene in the pathophysiological process of sepsis caused by ADAM10 dysregulation.

Prefrontal cortical protease TACE/ADAM17 is involved in neuroinflammation and stress-related eating alterations

Childhood traumatic stress profoundly affects prefrontal cortical networks regulating top-down control of eating and body weight. However, the neurobiological mechanisms contributing to trauma-induced aberrant eating behaviors remain largely unknown. Traumatic stress influences brain immune responses, which may, in turn, disrupt prefrontal cortical networks and behaviors. The tumor necrosis factor alpha-converting enzyme / a disintegrin and metalloproteinase 17 (TACE/ADAM17) is a sheddase with essential functions in brain maturation, behavior, and neuroinflammation. This study aimed to determine the role of TACE/ADAM17 on traumatic stress-induced disruption of eating patterns. We demonstrate a novel mechanistic connection between prefrontal cortical TACE/ADAM17 and trauma-induced eating behaviors. Fifty-two (52) adolescent Lewis rats (postnatal day, PND, 15) were injected intracerebrally either with a novel Accell™ SMARTpool ADAM17 siRNA or a corresponding siRNA vehicle. The RNAscope Multiplex Fluorescent v2 Assay was used to visualize mRNA expression. Observation cages were used to monitor ethological behaviors in a more naturalistic environment over long periods. We found that traumatic stress blunts startle reactivity and alter eating behaviors (increased intake and disrupted eating patterns). We also found that the rats that received prefrontal cortical TACE/ADAM17 siRNA administration exhibited decreased eating and increased grooming behaviors compared to controls. These changes were associated with decreased AIF-1 expression (a typical marker of microglia and neuroinflammation). This study demonstrates that prefrontal cortical TACE/ADAM17 is involved in neuroinflammation and may play essential roles in regulating feeding patterns under stress conditions. TACE/ADAM17 represents a promising target to ameliorate inflammation-induced brain and behavior alterations.

A Bioengineering Strategy to Control ADAM10 Activity in Living Cells

A Disintegrin and Metalloprotease 10, also known as ADAM10, is a cell surface protease ubiquitously expressed in mammalian cells where it cuts several membrane proteins implicated in multiple physiological processes. The dysregulation of ADAM10 expression and function has been implicated in pathological conditions, including Alzheimer's disease (AD). Although it has been suggested that ADAM10 is expressed as a zymogen and the removal of the prodomain results in its activation, other potential mechanisms for the ADAM10 proteolytic function and activation remain unclear. Another suggested mechanism is post-translational modification of the cytoplasmic domain, which regulates ADAM10-dependent protein ectodomain shedding. Therefore, the precise and temporal activation of ADAM10 is highly desirable to reveal the fine details of ADAM10-mediated cleavage mechanisms and protease-dependent therapeutic applications. Here, we present a strategy to control prodomain and cytosolic tail cleavage to regulate ADAM10 shedding activity without the intervention of small endogenous molecule signaling pathways. We generated a series of engineered ADAM10 analogs containing Tobacco Etch Virus protease (TEV) cleavage site (TEVcs), rendering ADAM10 cleavable by TEV. This strategy revealed that, in the absence of other stimuli, the TEV-mediated removal of the prodomain could not activate ADAM10. However, the TEV-mediated cleavage of the cytosolic domain significantly increased ADAM10 activity. Then, we generated ADAM10 with a minimal constitutively catalytic activity that increased significantly in the presence of TEV or after activating a chemically activatable TEV. Our results revealed a bioengineering strategy for controlling the ADAM10 activity in living cells, paving the way to obtain spatiotemporal control of ADAM10. Finally, we proved that our approach of controlling ADAM10 promoted α-secretase activity and the non-amyloidogenic cleavage of amyloid-β precursor protein (APP), thereby increasing the production of the neuroprotective soluble ectodomain (sAPPα). Our bioengineering strategy has the potential to be exploited as a next-generation gene therapy for AD.

The versatile roles of ADAM8 in cancer cell migration, mechanics, and extracellular matrix remodeling

The posttranslational proteolytic cleavage is a unique and irreversible process that governs the function and half-life of numerous proteins. Thereby the role of the family of A disintegrin and metalloproteases (ADAMs) plays a leading part. A member of this family, ADAM8, has gained attention in regulating disorders, such as neurogenerative diseases, immune function and cancer, by attenuating the function of proteins nearby the extracellular membrane leaflet. This process of "ectodomain shedding" can alter the turnover rate of a number of transmembrane proteins that function in cell adhesion and receptor signal transduction. In the past, the major focus of research about ADAMs have been on neurogenerative diseases, such as Alzheimer, however, there seems to be evidence for a connection between ADAM8 and cancer. The role of ADAMs in the field of cancer research has gained recent attention, but it has been not yet been extensively addressed. Thus, this review article highlights the various roles of ADAM8 with particular emphasis on pathological conditions, such as cancer and malignant cancer progression. Here, the shedding function, direct and indirect matrix degradation, effects on cancer cell mobility and transmigration, and the interplay of ADAM8 with matrix-embedded neighboring cells are presented and discussed. Moreover, the most probable mechanical impact of ADAM8 on cancer cells and their matrix environment is addressed and debated. In summary, this review presents recent advances in substrates/ligands and functions of ADAM8 in its new role in cancer and its potential link to cell mechanical properties and discusses matrix mechanics modifying properties. A deeper comprehension of the regulatory mechanisms governing the expression, subcellular localization, and activity of ADAM8 is expected to reveal appropriate drug targets that will permit a more tailored and fine-tuned modification of its proteolytic activity in cancer development and metastasis.

The immunological role of ADAMs in the field of gastroenterological chronic inflammatory diseases and cancers: a review

Metalloproteinases cleave transmembrane proteins that play critical roles in inflammation and cancers. Metalloproteinases include a disintegrin and metalloprotease (ADAM), which we previously examined using a fluorescence assay system, and described their association with resistance to systemic therapy in cancer patients. There are also many reports on the relation between ADAM expression and the prognosis of patients with gastroenterological chronic inflammatory diseases and cancers. Inhibiting their immunomodulating activity in chronic inflammation restores innate immunity and potentially prevents the development of various cancers. Among the numerous critical immune system-related molecules, we focus on major histocompatibility complex class I polypeptide-related sequence A (MICA), MICB, intracellular adhesion molecule (ICAM)-1, TNF-α, IL-6 receptor (IL-6R), and Notch. This review summarizes our current understanding of the role of ADAMs in gastroenterological diseases with regard to the immune system. Several Food and Drug Administration (FDA)-approved inhibitors of ADAMs have been identified, and potential therapies for targeting ADAMs in the treatment of chronic inflammatory diseases and cancers are discussed. Some ongoing clinical trials for cancers targeting ADAMs are also introduced.

Metzincin metalloproteases in PGC migration and gonadal sex conversion

Development of a functional gonad includes migration of primordial germ cells (PGCs), differentiations of somatic and germ cells, formation of primary follicles or spermatogenic cysts with somatic gonadal cells, development and maturation of gametes, and subsequent releasing of mature germ cells. These processes require extensive cellular and tissue remodeling, as well as broad alterations of the surrounding extracellular matrix (ECM). Metalloproteases, including MMPs (matrix metalloproteases), ADAMs (a disintegrin and metalloproteinases), and ADAMTS (a disintegrin and metalloproteinase with thrombospondin motifs), are suggested to have critical roles in the remodeling of the ECM during gonad development. However, few research articles and reviews are available on the functions and mechanisms of metalloproteases in remodeling gonadal ECM, gonadal development, or gonadal differentiation. Moreover, most studies focused on the roles of transcription and growth factors in early gonad development and primary sex determination, leaving a significant knowledge gap on how differentially expressed metalloproteases exert effects on the ECM, cell migration, development, and survival of germ cells during the development and differentiation of ovaries or testes. We will review gonad development with focus on the evidence of metalloprotease involvements, and with an emphasis on zebrafish as a model for studying gonadal sex differentiation and metalloprotease functions.

MT1-MMP and ADAM10/17 exhibit a remarkable overlap of shedding properties

Membrane-type-I matrix metalloproteinase (MT1-MMP) is one of six human membrane-bound MMPs and is responsible for extracellular matrix remodelling by degrading several substrates like fibrillar collagens, including types I-III, or fibronectin. Moreover, MT1-MMP was described as a key player in cancer progression and it is involved in various inflammatory processes, as well as in the pathogenesis of Alzheimer's disease (AD). The membrane-tethered metalloprotease meprin β as well as a disintegrin and metalloproteinase 10 (ADAM10) and ADAM17 are also associated with these diseases. Interestingly, meprin β, ADAM10/17 and MT1-MMP also have a shared substrate pool including the interleukin-6 receptor and the amyloid precursor protein. We investigated the interaction of these proteases, focusing on a possible connection between MT1-MMP and meprin β, to elucidate the potential mutual regulations of both enzymes. Herein, we show that besides ADAM10/17, MT1-MMP is also able to shed meprin β from the plasma membrane, leading to the release of soluble meprin β. Mass spectrometry-based cleavage site analysis revealed that the cleavage of meprin β by all three proteases occurs between Pro₆₀₂ and Ser₆₀₃ , N-terminal of the EGF-like domain. Furthermore, only inactive human pro-meprin β is shed by MT1-MMP, which is again in accordance with the shedding capability observed for ADAM10/17. Vice versa, meprin β also appears to shed MT1-MMP, indicating a complex regulatory network. Further studies will elucidate this well-orchestrated proteolytic web under distinct conditions in health and disease and will possibly show whether the loss of one of the above-mentioned sheddases can be compensated by the other enzymes.

Targeting cardiomyocyte ADAM10 ectodomain shedding promotes survival early after myocardial infarction

After myocardial infarction the innate immune response is pivotal in clearing of tissue debris as well as scar formation, but exaggerated cytokine and chemokine secretion with subsequent leukocyte infiltration also leads to further tissue damage. Here, we address the value of targeting a previously unknown a disintegrin and metalloprotease 10 (ADAM10)/CX3CL1 axis in the regulation of neutrophil recruitment early after MI. We show that myocardial ADAM10 is distinctly upregulated in myocardial biopsies from patients with ischemia-driven cardiomyopathy. Intriguingly, upon MI in mice, pharmacological ADAM10 inhibition as well as genetic cardiomycyte-specific ADAM10 deletion improves survival with markedly enhanced heart function and reduced scar size. Mechanistically, abolished ADAM10-mediated CX3CL1 ectodomain shedding leads to diminished IL-1β-dependent inflammation, reduced neutrophil bone marrow egress as well as myocardial tissue infiltration. Thus, our data shows a conceptual insight into how acute MI induces chemotactic signaling via ectodomain shedding in cardiomyocytes.

Transcriptomic mapping of the metzincin landscape in human trophoblasts

The metzincin family of metalloproteases coordinates tissue developmental processes through regulation of growth factor availability, receptor signaling, and cell-cell/cell-matrix adhesion. While roles for select metzincins in controlling trophoblast functions in human placental development have been described, a comprehensive understanding of metzincin dynamics during trophoblast differentiation is lacking. To address this knowledge gap, single cell transcriptomic datasets derived from first trimester chorionic villi and decidua were used to decipher metzincin expression profiles and kinetics in diverse cell types within the utero-placental interface. Further, specific protease-substrate interactions within progenitor trophoblasts were examined to better define the progenitor niche. Within the uterine-placental compartment, 43 metzincin proteases were expressed across 15 cell-type clusters. Metzincin subgroups expressed in placental trophoblasts, placental mesenchymal cells, uterine stromal, and immune cells included multiple matrix metalloproteases (MMPs), a disintegrin and metalloproteases (ADAMs), a disintegrin and metalloproteases with thrombospondin repeats (ADAMTSs), pappalysins, and astacins. Within the trophoblast compartment, eight distinct trophoblasts states were identified: four cytotrophoblast (CTB), one syncytiotrophoblast precursor (SCTp), two column CTB (cCTB), and one extravillous trophoblast (EVT). Within these states 7 MMP, 8 ADAM, 4 ADAMTS, 2 pappalysin, and 3 astacin proteases were expressed. Cell trajectory modeling shows that expression of most (19/24) metzincins increase during EVT differentiation, though expression of select metalloproteases increase along the villous pathway. Eleven metzincins (ADAM10, -17, MMP14, -15, -19, -23B, ADAMTS1, -6, -19, TLL-1, -2) showed enrichment within CTB progenitors, and analysis of metzincin-substrate interactions identified ∼150 substrates and binding partners, including FBN2 as an ADAMTS6-specific substrate. Together, this work characterizes the metzincin landscape in human first trimester trophoblasts and establishes insight into the roles specific proteases perform within distinct trophoblast niches and across trophoblast differentiation. This resource serves as a guide for future investigations into the roles of metzincin proteases in human placental development.

Junctional epithelium and hemidesmosomes: Tape and rivets for solving the "percutaneous device dilemma" in dental and other permanent implants

The percutaneous device dilemma describes etiological factors, centered around the disrupted epithelial tissue surrounding non-remodelable devices, that contribute to rampant percutaneous device infection. Natural percutaneous organs, in particular their extracellular matrix mediating the "device"/epithelium interface, serve as exquisite examples to inspire longer lasting long-term percutaneous device design. For example, the tooth's imperviousness to infection is mediated by the epithelium directly surrounding it, the junctional epithelium (JE). The hallmark feature of JE is formation of hemidesmosomes, cell/matrix adhesive structures that attach surrounding oral gingiva to the tooth's enamel through a basement membrane. Here, the authors survey the multifaceted functions of the JE, emphasizing the role of the matrix, with a particular focus on hemidesmosomes and their five main components. The authors highlight the known (and unknown) effects dental implant - as a model percutaneous device - placement has on JE regeneration and synthesize this information for application to other percutaneous devices. The authors conclude with a summary of bioengineering strategies aimed at solving the percutaneous device dilemma and invigorating greater collaboration between clinicians, bioengineers, and matrix biologists.

TIMP3 Gene Polymorphisms of -1296 T > C and -915 A > G Increase the Susceptibility to Arsenic-Induced Skin Cancer: A Cohort Study and In Silico Analysis of Mutation Impacts

Long-term exposure to arsenic may induce several human cancers, including non-melanoma skin cancer. The tissue inhibitor of metalloproteinase (TIMP)-3, encoded by the TIMP3 gene, may inhibit tumor growth, invasion, and metastasis of several cancer types. In this study, we aimed to investigate effects of the TIMP3 -1296 T > C (rs9619311) and -915 A > G (rs2234921) single-nucleotide polymorphisms (SNPs) on skin cancer risk in an arsenic-exposed population, and to evaluate the influence of allele-specific changes by an in silico analysis. In total, 1078 study participants were followed up for a median of 15 years for newly diagnosed skin cancer. New cases were identified through linkage to the National Cancer Registry of Taiwan. A Cox regression analysis was used to evaluate the effects of TIMP3 variants. Transcription factor (TF) profiling of binding sites of allele-specific changes in SNPs was conducted using the JASPAR scan tool. We observed borderline associations between TIMP3 genotypes and skin cancer risk. However, when combined with high arsenic exposure levels, the rs9619311 C allele, rs2234921 G allele, or C-G haplotype groups exhibited a greater risk of developing skin cancer compared to the respective common homozygous genotype group. The in silico analysis revealed several TF motifs located at or flanking the two SNP sites. We validated that the C allele of rs9619311 attenuated the binding affinity of BACH2, MEIS2, NFE2L2, and PBX2 to the TIMP3 promoter, and that the G allele of rs2234921 reduced the affinity of E2F8 and RUNX1 to bind to the promoter. Our findings suggest significant modifications of the effect of the association between arsenic exposure and skin cancer risk by the TIMP3 rs9619311 and rs2234921 variants. The predicted TFs and their differential binding affinities to the TIMP3 promoter provide insights into how TIMP3 interacts with arsenic through TFs in skin cancer formation.

Protein-Labeling Fluorescent Probe Reveals Ectodomain Shedding of Transmembrane Carbonic Anhydrases

Ectodomain shedding is a form of limited proteolysis in which a protease cleaves a transmembrane protein, releasing the extracellular domain from the cell surface. Cells use this process to regulate a wide variety of biological events. Typically, immunological detection methods are employed for the analysis of ectodomains secreted into the cultured media. In this paper, we describe a new strategy using an affinity-based protein-labeling fluorescent probe to study ectodomain shedding. We analyzed the ectodomain shedding of cell surface carbonic anhydrases (CAIX and CAXII), which are important biomarkers for tumor hypoxia. Using both chemical and genetic approaches, we identified that the ADAM17 metalloprotease is responsible for the shedding of carbonic anhydrases. Compared to current immunological methods, this protein-labeling approach not only detects ectodomain released into the culture media but also allows real-time living cell tracking and quantitative analysis of remnant proteins on the cell surface, thereby providing a more detailed insight into the mechanism of ectodomain shedding as well as protein lifetime on the cell surface.

Adam10-dependent Notch signaling establishes dental epithelial cell boundaries required for enamel formation

The disintegrin and metalloproteinase Adam10 is a membrane-bound sheddase that regulates Notch signaling and ensures epidermal integrity. To address the function of Adam10 in the continuously growing incisors, we used Keratin14^Cre/+;Adam10^fl/fl transgenic mice, in which Adam10 is conditionally deleted in the dental epithelium. Keratin14^Cre/+;Adam10^fl/fl mice exhibited severe abnormalities, including defective enamel formation reminiscent of human enamel pathologies. Histological analyses of mutant incisors revealed absence of stratum intermedium, and severe disorganization of enamel-secreting ameloblasts. In situ hybridization and immunostaining analyses in the Keratin14^Cre/+;Adam10^fl/fl incisors showed strong Notch1 downregulation in dental epithelium and ectopic distribution of enamel-specific molecules, including ameloblastin and amelogenin. Lineage tracing studies using Notch1^CreERT2;R26^mT/mG mice demonstrated that loss of the stratum intermedium cells was due to their fate switch toward the ameloblast lineage. Overall, our data reveal that in the continuously growing incisors the Adam10/Notch axis controls dental epithelial cell boundaries, cell fate switch and proper enamel formation.

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ADAM10 deletion in the dental epithelium causes the formation of defective enamel

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ADAM10 deletion leads to loss of stratum intermedium and Notch1 expression

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ADAM10 deletion leads to stratum intermedium-to-ameloblast cell fate switch

Human Malignant Rhabdoid Tumor Antigens as Biomarkers and Potential Therapeutic Targets

Simple Summary

Atypical teratoid rhabdoid tumor (ATRT) is a deadly type of human pediatric brain cancer without effective treatments. ATRT is mainly linked to the inactivation of a tumor suppressor gene, SMARCB1; however, additional biomarkers remain to be identified to develop novel therapeutic strategies. Therefore, different tumor antigens and extracellular matrix modulators were investigated in two human ATRT and one kidney malignant rhabdoid tumor cell lines and compared with the nonmalignant HEK293 cell line. Alpha-fetoprotein (AFP), mucin-16 (MUC16 or cancer antigen 125/CA125), osteopontin (OPN), and mesothelin (MSLN) are highly expressed in these human malignant rhabdoid cancer cell lines. Inhibiting MMPs using a small-molecule inhibitor decreased cell survival. This biomarker discovery process may lead to the identification of novel diagnostic and therapeutic strategies, such as the development of targeted and immunotherapies against cancer biomarkers, to treat cancer patients.

Abstract

Introduction: Atypical teratoid rhabdoid tumor (ATRT) is a lethal type of malignant rhabdoid tumor in the brain, seen mostly in children under two years old. ATRT is mainly linked to the biallelic inactivation of the SMARCB1 gene. To understand the deadly characteristics of ATRT and develop novel diagnostic and immunotherapy strategies for the treatment of ATRT, this study investigated tumor antigens, such as alpha-fetoprotein (AFP), mucin-16 (MUC16/CA125), and osteopontin (OPN), and extracellular matrix modulators, such as matrix metalloproteinases (MMPs), in different human malignant rhabdoid tumor cell lines. In addition, the roles of MMPs were also examined. Materials and methods: Five human cell lines were chosen for this study, including two ATRT cell lines, CHLA-02-ATRT and CHLA-05-ATRT; a kidney malignant rhabdoid tumor cell line, G401; and two control cell lines, human embryonic kidney HEK293 and HEK293T. Both ATRT cell lines were treated with a broad-spectrum MMP inhibitor, GM6001, to investigate the effect of MMPs on cell proliferation, viability, and expression of tumor antigens and biomarkers. Gene expression was examined using a reverse transcription polymerase chain reaction (RT-PCR), and protein expression was characterized by immunocytochemistry and flow cytometry. Results: All the rhabdoid tumor cell lines tested had high gene expression levels of MUC16, OPN, AFP, and MSLN. Low expression levels of neuron-specific enolase (ENO2) by the two ATRT cell lines demonstrated their lack of neuronal genotype. Membrane-type 1 matrix metalloproteinase (MT1-MMP/MMP-14) and tissue inhibitor of metalloproteinases-2 (TIMP-2) were highly expressed in these malignant rhabdoid tumor cells, indicating their invasive phenotypes. GM6001 significantly decreased ATRT cell proliferation and the gene expression of MSLN, OPN, and several mesenchymal markers, suggesting that inhibition of MMPs may reduce the aggressiveness of rhabdoid cancer cells. Conclusion: The results obtained from this study may advance our knowledge of the molecular landscapes of human malignant rhabdoid tumors and their biomarkers for effective diagnosis and treatment. This work analyzed the expression of human malignant rhabdoid tumor antigens that may serve as biomarkers for the development of novel therapeutic strategies, such as cancer vaccines and targeted and immunotherapies targeting osteopontin and mesothelin, for the treatment of patients with ATRT and other malignant rhabdoid tumors.

Interval-Based Secretomics Unravels Acute-Phase Response in Hepatocyte Model Systems

Mass spectrometry-based secretomics approaches frequently utilize serum-free culture conditions to circumvent serum-induced interference and to increase analytical depth. However, this can negatively affect a wide range of cellular functions and cell viability. These effects become particularly apparent when investigating transcriptionally regulated secretion events and feedback-loops in response to perturbations that require 48 h or more to fully manifest. We present an “interval-based” secretomics workflow, which determines protein secretion rates in short serum-free time windows. Relative quantification using tandem mass tags enables precise monitoring of time-dependent changes. We applied this approach to determine temporal profiles of protein secretion in the hepatocyte model cell lines HepG2 and HepaRG after stimulation of the acute-phase response (APR) by the cytokines IL1b and IL6. While the popular hepatocarcinoma cell line HepG2 showed an incomplete APR, secretion patterns derived from differentiated HepaRG cells recapitulated the expected APR more comprehensively. For several APR response proteins, substantial secretion was only observed after 72 h, a time window at which cell fitness is substantially impaired under serum-free cell culture conditions. The interval-based secretomics approach enabled the first comprehensive analysis of time-dependent secretion of liver cell models in response to these proinflammatory cytokines. The extended time range facilitated the observation of distinct chronological phases and cytokine-dependent secretion phenotypes of the APR. IL1b directed the APR toward pathogen defense over three distinct phases—chemotaxis, effector, clearance—while IL6 directed the APR toward regeneration. Protein shedding on the cell surface was pronounced upon IL1b stimulation, and small molecule inhibition of ADAM and matrix metalloproteases identified induced as well as constitutive shedding events. Inhibition of ADAM proteases with TAPI-0 resulted in reduced shedding of the sorting receptor SORT1, and an attenuated cytokine response suggesting a direct link between cell surface shedding and cytokine secretion rates.

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Interval-based secretomics enables extended time course analysis.

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Time-resolved acute phase response in liver model systems HepG2 and HepaRG.

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IL1b response clusters in three phases.

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Cell surface shedding is amplified during acute-phase response.

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ADAM inhibition dampens secretion of inflammatory cytokines.

Quantitative Proteomics Reveals That ADAM15 Can Have Proteolytic-Independent Functions in the Steady State

A disintegrin and metalloproteinase 15 (ADAM15) is a member of the ADAM family of sheddases. Its genetic ablation in mice suggests that ADAM15 plays an important role in a wide variety of biological functions, including cartilage homeostasis. Nevertheless, while the substrate repertoire of other members of the ADAM family, including ADAM10 and ADAM17, is largely established, little is known about the substrates of ADAM15 and how it exerts its biological functions. Herein, we used unbiased proteomics to identify ADAM15 substrates and proteins regulated by the proteinase in chondrocyte-like HTB94 cells. ADAM15 silencing did not induce major changes in the secretome composition of HTB94 cells, as revealed by two different proteomic approaches. Conversely, overexpression of ADAM15 remodeled the secretome, with levels of several secreted proteins being altered compared to GFP-overexpressing controls. However, the analysis did not identify potential substrates of the sheddase, i.e., transmembrane proteins released by ADAM15 in the extracellular milieu. Intriguingly, secretome analysis and immunoblotting demonstrated that ADAM15 overexpression increased secreted levels of tissue inhibitor of metalloproteinases 3 (TIMP-3), a major regulator of extracellular matrix turnover. An inactive form of ADAM15 led to a similar increase in the inhibitor, indicating that ADAM15 regulates TIMP-3 secretion by an unknown mechanism independent of its catalytic activity. In conclusion, high-resolution quantitative proteomics of HTB94 cells manipulated to have increased or decreased ADAM15 expression did not identify canonical substrates of the proteinase in the steady state, but it revealed that ADAM15 can modulate the secretome in a catalytically-independent manner.

Expression of matrix metalloproteinase-3 and -10 is up-regulated in the periodontal tissues of aged mice

Objective

The present study was designed to investigate the whole transcriptome of periodontal tissues of both young and aged mice to identify the characteristic up‐regulation of protease genes with aging and to localize their translated protein products in the periodontal tissues.

Background

The metzincin protease superfamily is composed of matrix metalloproteinases (MMPs), a disintegrin and metalloproteinases, and a disintegrin and metalloproteinases with thrombospondin motifs. Up‐regulation of these extracellular matrix‐degrading proteases has been implicated in senescence of tissues and organs, including the skin. However, few studies have investigated the expression profiles of these proteases and potential involvement in aging of periodontal tissues.

Methods

Periodontal tissues with the surrounding mandibular bones were collected from 50‐ and 10‐week‐old mice. Total RNA was extracted from the periodontal tissue and analyzed by cap analysis of gene expression (CAGE) to identify differentially expressed genes encoding the metzincin proteases. Furthermore, quantitative real‐time polymerase chain reaction (qRT‐PCR) was performed to validate the CAGE results, and the phenotypic expression of proteases involved in aging was localized via immunohistochemical analysis.

Results

The CAGE results showed that the expression levels of MMP‐3, ‐10, and ‐12 were up‐regulated at 50 weeks. Subsequent qRT‐PCR analysis showed that the gene expression levels of MMP‐3 and ‐10 were significantly increased with age. MMP‐10 immunoreactivity was localized exclusively in the cementum and alveolar bone adjacent to the periodontal ligament and was stronger and broader in aged mice than young mice. MMP‐3 immunoreactivity was localized in the periodontal ligaments at both 10 and 50 weeks.

Conclusion

In the present study, we demonstrated that the expression of MMP‐3 and ‐10 increased with aging and identified their characteristic localizations in aged periodontal tissues.

Ars moriendi: Proteases as sculptors of cellular suicide

The Ars moriendi, which translates to "The Art of Dying," encompasses two Latin texts that gave advice on how to die well and without fear according to the Christian precepts of the late Middle Ages. Given that ten to hundred billion cells die in our bodies every day, it is obvious that the concept of a well and orderly ("regulated") death is also paramount at the cellular level. In apoptosis, as the most well-studied form of regulated cell death, proteases of the caspase family are the central mediators. However, caspases are not the only proteases that act as sculptors of cellular suicide, and therefore, we here provide an overview of the impact of proteases in apoptosis and other forms of regulated cell death.

Robo4 is constitutively shed by ADAMs from endothelial cells and the shed Robo4 functions to inhibit Slit3-induced angiogenesis

Roundabout 4 (Robo4) is a transmembrane receptor that expresses specifically in endothelial cells. Soluble Robo4 was reported in the human plasma and mouse serum and is inhibitory towards FGF- and VEGF-induced angiogenesis. It remains unknown how soluble Robo4 is generated and if soluble Robo4 regulates additional angiogenic signaling. Here, we report soluble Robo4 is the product of constitutive ectodomain shedding of endothelial cell surface Robo4 by disintegrin metalloproteinases ADAM10 and ADAM17 and acts to inhibit angiogenic Slit3 signaling. Meanwhile, the ligand Slit3 induces cell surface receptor Robo4 endocytosis to shield Robo4 from shedding, showing Slit3 inhibits Robo4 shedding to enhance Robo4 signaling. Our study delineated ADAM10 and ADAM17 are Robo4 sheddases, and ectodomain shedding, including negative regulation by its ligand Slit3, represents a novel control mechanism of Robo4 signaling in angiogenesis.

Resveratrol Inhibited ADAM10 Mediated CXCL16-Cleavage and T-Cells Recruitment to Pancreatic β-Cells in Type 1 Diabetes Mellitus in Mice

Background: CXCL16 attracts T-cells to the site of inflammation after cleaving by A Disintegrin and Metalloproteinase (ADAM10). Aim: The current study explored the role of ADAM10/CXCL16/T-cell/NF-κB in the initiation of type 1 diabetes (T1D) with special reference to the potential protecting role of resveratrol (RES). Methods: Four sets of Balb/c mice were created: a diabetes mellitus (DM) group (streptozotocin (STZ) 55 mg/kg, i.p.], a control group administered buffer, a RES group [RES, 50 mg/kg, i.p.), and a DM + RES group (RES (50 mg/kg, i.p.) and STZ (55 mg/kg, i.p.) administered daily for 12 days commencing from the fourth day of STZ injection). Histopathological changes, fasting blood insulin (FBI), glucose (FBG), serum and pancreatic ADAM10, CXCL16, NF-κB, T-cells pancreatic expression, inflammatory, and apoptotic markers were analyzed. Results: FBG, inflammatory and apoptotic markers, serum TNF-α, cellular CXCL16 and ADAM10 protein expression, pancreatic T-cell migration and NF-κB were significantly increased in diabetic mice compared to normal mice. RES significantly improved the biochemical and inflammatory parameters distorted in STZ-treated mice. Conclusions: ADAM10 promotes the cleaved form of CXCL16 driving T-cells into the islets of the pancreatic in T1D. RES successfully prevented the deleterious effect caused by STZ. ADAM10 and CXCL16 may serve as novel therapeutic targets for T1D.

shRNAs targeting mouse Adam10 diminish cell response to proinflammatory stimuli independently of Adam10 silencing

RNA interference is one of the common methods of studying protein functions. In recent years critical reports have emerged indicating that off-target effects may have a much greater impact on RNAi-based analysis than previously assumed. We studied the influence of Adam10 and Adam17 silencing on MC38CEA cell response to proinflammatory stimuli. Eight lentiviral vector-encoded shRNAs that reduced ADAM10 expression, including two that are specific towards ADAM17, caused inhibition of cytokine-induced Nos2 expression presumably via off-target effects. ADAM10 silencing was not responsible for this effect because: (i) CRISPR/Cas9 knockdown of ADAM10 did not affect Nos2 levels; (ii) ADAM10 inhibitor increased rather than decreased Nos2 expression; (iii) overexpression of ADAM10 in the cells with shRNA-silenced Adam10 did not reverse the effect induced by shRNA; (iv) shRNA targeting ADAM10 resulted in decrease of Nos2 expression even in ADAM10-deficient cells. The studied shRNAs influenced transcription of Nos2 rather than stability of Nos2 mRNA. They also affected stimulation of Ccl2 and Ccl7 expression. Additionally, we used vectors with doxycycline-inducible expression of chosen shRNAs and observed reduced activation of NF-κB and, to a lesser extent, AP-1 transcription factors. We discuss the requirements of strict controls and verification of results with complementary methods for reliable conclusions of shRNA-based experiments.

Summary: Use of several specific shRNAs is not enough to escape a pitfall of their off-target activity: the case of Adam10 and Adam17 silencing.

Immune Responses to IAV Infection and the Roles of L-Selectin and ADAM17 in Lymphocyte Homing

Influenza A virus (IAV) infection is a global public health burden causing up to 650,000 deaths per year. Yearly vaccination programmes and anti-viral drugs currently have limited benefits; therefore, research into IAV is fundamental. Leukocyte trafficking is a crucial process which orchestrates the immune response to infection to protect the host. It involves several homing molecules and receptors on both blood vessels and leukocytes. A key mediator of this process is the transmembrane glycoprotein L-selectin, which binds to vascular addressins on blood vessel endothelial cells. L-selectin classically mediates homing of naïve and central memory lymphocytes to lymph nodes via high endothelial venules (HEVs). Recent studies have found that L-selectin is essential for homing of activated CD8⁺ T cells to influenza-infected lungs and reduction in virus load. A disintegrin and metalloproteinase 17 (ADAM17) is the primary regulator of cell surface levels of L-selectin. Understanding the mechanisms that regulate these two proteins are central to comprehending recruitment of T cells to sites of IAV infection. This review summarises the immune response to IAV infection in humans and mice and discusses the roles of L-selectin and ADAM17 in T lymphocyte homing during IAV infection.

Peptidome: Chaos or Inevitability

Thousands of naturally occurring peptides differing in their origin, abundance and possible functions have been identified in the tissue and biological fluids of vertebrates, insects, fungi, plants and bacteria. These peptide pools are referred to as intracellular or extracellular peptidomes, and besides a small proportion of well-characterized peptide hormones and defense peptides, are poorly characterized. However, a growing body of evidence suggests that unknown bioactive peptides are hidden in the peptidomes of different organisms. In this review, we present a comprehensive overview of the mechanisms of generation and properties of peptidomes across different organisms. Based on their origin, we propose three large peptide groups-functional protein "degradome", small open reading frame (smORF)-encoded peptides (smORFome) and specific precursor-derived peptides. The composition of peptide pools identified by mass-spectrometry analysis in human cells, plants, yeast and bacteria is compared and discussed. The functions of different peptide groups, for example the role of the "degradome" in promoting defense signaling, are also considered.

Serum N-terminal DDR1: A Novel Diagnostic Marker of Liver Fibrosis Severity

BACKGROUND AND AIMS

The expression of discoidin domain receptor 1 (DDR1) is commonly up-regulated and undergoes collagen-induced ectodomain (N-terminal) shedding during the progression of liver fibrosis. This study aimed to evaluate the clinical utility of N-terminal DDR1 as a diagnostic biomarker for liver fibrosis.

METHODS

N-terminal DDR1 shedding was evaluated using cell lines, liver fibrosis mouse models, clinical data of 298 patients collected from February 2019 to June 2020. The clinical data were divided into test and validation cohorts to evaluate the diagnostic performance of serum N-terminal DDR1.

RESULTS

Time- and dosage-dependent N-terminal DDR1 shedding stimulated by collagen I was observed in a hepatocyte cell line model. The type I collagen deposition and serum N-terminal DDR1 levels concurrently increased in the development of liver fibrosis in mouse models. Clinical data demonstrated a significant diagnostic power of serum N-terminal DDR1 levels as an accurate biomarker of liver fibrosis and cirrhosis. The diagnostic performance was further increased when applying N-DDR1/albumin ratio, achieving area under the curve of 0.790, 0.802, 0.879, and 0.865 for detecting histological fibrosis stages F ≥2, F ≥3, F 4 with liver biopsy as a reference method, and cirrhosis according to imaging techniques, respectively. With a cut-off of 55.6, a sensitivity, specificity, positive predictive value, and negative predictive value of 82.7%,76.6%, 67.4%, and 88.3% were achieved for the detection of cirrhosis.

CONCLUSIONS

Serum N-terminal DDR1 appears to be a novel diagnostic marker for liver fibrosis.

Ectodomain shedding by ADAM proteases as a central regulator in kidney physiology and disease

Besides its involvement in blood and bone physiology, the kidney's main function is to filter substances and thereby regulate the electrolyte composition of body fluids, acid-base balance and toxin removal. Depending on underlying conditions, the nephron must undergo remodeling and cellular adaptations. The proteolytic removal of cell surface proteins via ectodomain shedding by A Disintegrin and Metalloproteases (ADAMs) is of importance for the regulation of cell-cell and cell-matrix adhesion of renal cells. ADAM10 controls glomerular and tubule development in a Notch1 signaling-dependent manner and regulates brush border composition. ADAM17 regulates the renin angiotensin system and is together with ADAM10 involved in calcium phosphate homeostasis. In kidney disease ADAMs, especially ADAM17 contribute to inflammation through their involvement in IL-6 trans-signaling, Notch-, epithelial growth factor receptor-, and tumor necrosis factor α signaling. ADAMs are interesting drug targets to reduce the inflammatory burden, defective cell adhesion and impaired signaling pathways in kidney diseases.

Adam21 is dispensable for reproductive processes in mice

BACKGROUND

As a group of membrane-anchored proteins, the proteins containing a disintegrin and metalloprotease domain (ADAMs) control many biological processes, especially for male fertility. Mouse Adam21 was previously found to be specifically expressed in the somatic cells and germ cells of testes, but its functional role during spermatogenesis and male reproductive processes is still unknown.

METHODS

Adam21-null mice were created using the CRISPR/Cas9 system. Quantitative real-time PCR was used for analyzing of gene expression. Histological, cytological and immunofluorescence staining were performed to analyze the phenotypes of mouse testis and epididymis. Intracellular lipid droplets (LDs) were detected by Oil red O (ORO) staining and BODIPY staining. Fertility and sperm characteristics were also detected.

RESULTS

Here, we successfully generated an Adam21 conventional knockout mouse model via CRISPR/Cas9 technology so that we can explore its potential role in male reproduction. We found that male mice lacking Adam21 have normal fertility without any detectable defects in spermatogenesis or sperm motility. Histological analysis of the seminiferous epithelium showed no obvious spermatogenesis difference between Adam21-null and wild-type mice. Cytological analysis revealed no detectable defects in meiotic progression, neither Sertoli cells nor Leydig cells displayed any defect compared with that of the control mice. All these results suggest that Adam21 might not be essential for male fertility in mice, and its potential function still needs further investigation.

Regulation of olfactomedin 4 by Porphyromonas gingivalis in a community context

At mucosal barriers, the virulence of microbial communities reflects the outcome of both dysbiotic and eubiotic interactions with the host, with commensal species mitigating or potentiating the action of pathogens. We examined epithelial responses to the oral pathogen Porphyromonas gingivalis as a monoinfection and in association with a community partner, Streptococcus gordonii. RNA-Seq of oral epithelial cells showed that the Notch signaling pathway, including the downstream effector olfactomedin 4 (OLFM4), was differentially regulated by P. gingivalis alone; however, regulation was overridden by S. gordonii. OLFM4 was required for epithelial cell migratory, proliferative and inflammatory responses to P. gingivalis. Activation of Notch signaling was induced through increased expression of the Notch1 receptor and the Jagged1 (Jag1) agonist. In addition, Jag1 was released in response to P. gingivalis, leading to paracrine activation. Following Jag1-Notch1 engagement, the Notch1 extracellular domain was cleaved by P. gingivalis gingipain proteases. Antagonism by S. gordonii involved inhibition of gingipain activity by secreted hydrogen peroxide. The results establish a novel mechanism by which P. gingivalis modulates epithelial cell function which is dependent on community context. These interrelationships have relevance for innate inflammatory responses and epithelial cell fate decisions in oral health and disease.

The Absence of Myelin Basic Protein Reduces Non-Amyloidogenic Processing of Amyloid Precursor Protein

BACKGROUND

The accumulation of amyloid β-protein (Aβ) in the brain is a pathological feature of Alzheimer's disease (AD). Aβ peptides originate from amyloid precursor protein (APP). APP can be proteolytically cleaved through amyloidogenic or non-amyloidogenic pathways. The molecular effects on APP metabolism / processing may be influenced by myelin and the breakdown of myelin basic protein (MBP) in AD patients and mouse models of AD pathology.

METHODS

We directly tested whether MBP can alter influence APP processing in MBP-/- mice, known as Shiverer (shi/shi) mice, in which no functional MBP is produced due to gene breakage from the middle of MBP exon II.

RESULTS

A significant reduction of the cerebral sAPPα level in Shiverer (shi/shi) mice was found, although the levels of both total APP and sAPPβ remain unchanged. The reduction of sAPPα was considered to be due to the changes in the expression levels of a disintegrin and metalloproteinase-9 (ADAM9) catalysis and non-amyloid genic processing of APP in the absence of MBP because it binds to ADAM9. MBP -/- mice exhibited increased Aβ oligomer production.

CONCLUSION

Together, these findings suggest that in the absence of MBP, there is a marked reduction of non-amyloidogenic APP processing to sAPPα, and targeting myelin of oligodendrocytes may be a novel therapy for the prevention and treatment of AD.

Novel Markers in Pediatric Acute Lymphoid Leukemia: The Role of ADAM6 in B Cell Leukemia

Background

The extensive genetic heterogeneity found in the B cell precursor acute lymphoblastic leukemia (BCP-ALL) subtype of childhood ALL represents a potential repository of biomarkers. To explore this potential, we have carried out in silico analysis of publicly available ALL datasets to identify genetic biomarkers for childhood BCP-ALL, which could be used either individually or in combination as markers for early detection, risk stratification, and prognosis.

Methods

To explore novel genes that show promising clinical and molecular signatures, we examined the cBioPortal online tool for publicly available datasets on lymphoid cancers. Three studies on lymphoblastic and lymphoid leukemia with 1706 patients and 2144 samples of which were identified. Only B-Lymphoblastic Leukemia/Lymphoma samples (n = 1978) were selected for further analysis. Chromosomal changes were assessed to determine novel genomic loci to analyze clinical and molecular profiles for the leukemia of lymphoid origin using cBioPortal tool.

Results

ADAM6 gene homozygous deletions (HOM:DEL) were present in 59.60% of the profiled patients and were associated with poor ten years of overall patients’ survival. Moreover, patients with ADAM6 HOM:DEL showed a distinguished clinical and molecular profile with higher Central Nervous System (CNS) sites of relapse. In addition, ADAM6 HOM:DEL was significantly associated with unique microRNAs gene expression patterns.

Conclusion

ADAM6 has the potential to be a novel biomarker for the development and progress of BCP- ALL.

Structural Studies Providing Insights into Production and Conformational Behavior of Amyloid-β Peptide Associated with Alzheimer's Disease Development

Alzheimer's disease is the most common type of neurodegenerative disease in the world. Genetic evidence strongly suggests that aberrant generation, aggregation, and/or clearance of neurotoxic amyloid-β peptides (Aβ) triggers the disease. Aβ accumulates at the points of contact of neurons in ordered cords and fibrils, forming the so-called senile plaques. Aβ isoforms of different lengths are found in healthy human brains regardless of age and appear to play a role in signaling pathways in the brain and to have neuroprotective properties at low concentrations. In recent years, different substances have been developed targeting Aβ production, aggregation, interaction with other molecules, and clearance, including peptide-based drugs. Aβ is a product of sequential cleavage of the membrane glycoprotein APP (amyloid precursor protein) by β- and γ-secretases. A number of familial mutations causing an early onset of the disease have been identified in the APP, especially in its transmembrane domain. The mutations are reported to influence the production, oligomerization, and conformational behavior of Aβ peptides. This review highlights the results of structural studies of the main proteins involved in Alzheimer's disease pathogenesis and the molecular mechanisms by which perspective therapeutic substances can affect Aβ production and nucleation.

Targeted truncation of the ADAM17 cytoplasmic domain in mice results in protein destabilization and a hypomorphic phenotype

A disintegrin and metalloprotease 17 (ADAM17) is a cell-surface metalloprotease that serves as the principle sheddase for tumor necrosis factor α (TNFα), interleukin-6 receptor (IL-6R), and several ligands of the epidermal growth factor receptor (EGFR), regulating these crucial signaling pathways. ADAM17 activation requires its transmembrane domain, but not its cytoplasmic domain, and little is known about the role of this domain in vivo. To investigate, we used CRISPR-Cas9 to mutate the endogenous Adam17 locus in mice to produce a mutant ADAM17 lacking its cytoplasmic domain (Adam17Δcyto). Homozygous Adam17Δcyto animals were born at a Mendelian ratio and survived into adulthood with slightly wavy hair and curled whiskers, consistent with defects in ADAM17/EGFR signaling. At birth, Adam17Δcyto mice resembled Adam17−/− mice in that they had open eyes and enlarged semilunar heart valves, but they did not have bone growth plate defects. The deletion of the cytoplasmic domain resulted in strongly decreased ADAM17 protein levels in all tissues and cells examined, providing a likely cause for the hypomorphic phenotype. In functional assays, Adam17Δcyto mouse embryonic fibroblasts and bone-marrow-derived macrophages had strongly reduced ADAM17 activity, consistent with the reduced protein levels. Nevertheless, ADAM17Δcyto could be stimulated by PMA, a well-characterized posttranslational activator of ADAM17, corroborating that the cytoplasmic domain of endogenous ADAM17 is not required for its rapid response to PMA. Taken together, these results provide the first evidence that the cytoplasmic domain of ADAM17 plays a pivotal role in vivo in regulating ADAM17 levels and function.

Heparan Sulfate Proteoglycans in Diabetes

Diabetes is a complex disorder responsible for the mortality and morbidity of millions of individuals worldwide. Although many approaches have been used to understand and treat diabetes, the role of proteoglycans, in particular heparan sulfate proteoglycans (HSPGs), has only recently received attention. The HSPGs are heterogeneous, highly negatively charged, and are found in all cells primarily attached to the plasma membrane or present in the extracellular matrix (ECM). HSPGs are involved in development, cell migration, signal transduction, hemostasis, inflammation, and antiviral activity, and regulate cytokines, chemokines, growth factors, and enzymes. Hyperglycemia, accompanying diabetes, increases reactive oxygen species and upregulates the enzyme heparanase that degrades HSPGs or affects the synthesis of the HSPGs altering their structure. The modified HSPGs in the endothelium and ECM in the blood vessel wall contribute to the nephropathy, cardiovascular disease, and retinopathy seen in diabetes. Besides the blood vessel, other cells and tissues in the heart, kidney, and eye are affected by diabetes. Although not well understood, the adipose tissue, intestine, and brain also reveal HSPG changes associated with diabetes. Further, HSPGs are significantly involved in protecting the β cells of the pancreas from autoimmune destruction and could be a focus of prevention of type I diabetes. In some circumstances, HSPGs may contribute to the pathology of the disease. Understanding the role of HSPGs and how they are modified by diabetes may lead to new treatments as well as preventative measures to reduce the morbidity and mortality associated with this complex condition.

Mechanistic insights of snake venom disintegrins in cancer treatment

Snake venoms are a potential source of various enzymatic and non-enzymatic compounds with a defensive role for the host. Various peptides with significant medicinal properties have been isolated and characterized from these venoms. Few of these are FDA approved. They inhibit tumor cells adhesion, migration, angiogenesis and metastasis by inhibiting integrins on transmembrane cellular surfaces. This plays important role in delaying tumor growth, neovascularization and development. Tumor targeting and smaller size make them ideal candidates as novel therapeutic agents for cancer treatment. This review is based on sources of these disintegrins, their targeting modality, classification and underlying anti-cancer potential.

Soluble TIM3 and Its Ligands Galectin-9 and CEACAM1 Are in Disequilibrium During Alcohol-Related Liver Disease and Promote Impairment of Anti-bacterial Immunity

Background and Aims

Immunoregulatory checkpoint receptors (CR) contribute to the profound immunoparesis observed in alcohol-related liver disease (ALD) and in vitro neutralization of inhibitory-CRs TIM3/PD1 on anti-bacterial T-cells can rescue innate and adaptive anti-bacterial immunity. Recently described soluble-CR forms can modulate immunity in inflammatory conditions, but the contributions of soluble-TIM3 and soluble-PD1 and other soluble-CRs to immune derangements in ALD remain unclear.

Methods

In Alcoholic Hepatitis (AH; n = 19), alcohol-related cirrhosis (ARC; n = 53) and healthy control (HC; n = 27) subjects, we measured by Luminex technology (i) plasma levels of 16 soluble-CRs, 12 pro/anti-inflammatory cytokines and markers of gut bacterial translocation; (ii) pre-hepatic, post-hepatic and non-hepatic soluble-CR plasma levels in ARC patients undergoing TIPS; (iii) soluble-CRs production from ethanol-treated immunocompetent precision cut human liver slices (PCLS); (iv) whole-blood soluble-CR expression upon bacterial challenge. By FACS, we assessed the relationship between soluble-TIM3 and membrane-TIM3 and rescue of immunity in bacterial-challenged PBMCs.

Results

Soluble-TIM3 was the dominant plasma soluble-CR in ALD vs. HC (p = 0.00002) and multivariate analysis identified it as the main driver of differences between groups. Soluble-CRs were strongly correlated with pro-inflammatory cytokines, gut bacterial translocation markers and clinical indices of disease severity. Ethanol exposure or bacterial challenge did not induce soluble-TIM3 production from PCLS nor from whole-blood. Bacterial challenge prompted membrane-TIM3 hyperexpression on PBMCs from ALD patient's vs. HC (p < 0.002) and was inversely correlated with plasma soluble-TIM3 levels in matched patients. TIM3 ligands soluble-Galectin-9 and soluble-CEACAM1 were elevated in ALD plasma (AH > ARC; p < 0.002). In vitro neutralization of Galectin-9 and soluble-CEACAM1 improved the defective anti-bacterial and anti-inflammatory cytokine production from E. coli-challenged PBMCs in ALD patients.

Conclusions

Alcohol-related liver disease patients exhibit supra-physiological plasma levels of soluble-TIM3, particularly those with greater disease severity. This is also associated with increased levels of soluble TIM3-ligands and membrane-TIM3 expression on immune cells. Soluble-TIM3 can block the TIM3-ligand synapse and improve anti-bacterial immunity; however, the increased levels of soluble TIM3-binding ligands in patients with ALD negate any potential immunostimulatory effects. We believe that anti-TIM3 neutralizing antibodies currently in Phase I clinical trials or soluble-TIM3 should be investigated further for their ability to enhance anti-bacterial immunity. These agents could potentially represent an innovative immune-based supportive approach to rescue anti-bacterial defenses in ALD patients.

Class II phosphatidylinositol 3-kinase-C2α is essential for Notch signaling by regulating the endocytosis of γ-secretase in endothelial cells

The class II α-isoform of phosphatidylinositol 3-kinase (PI3K-C2α) plays a crucial role in angiogenesis at least in part through participating in endocytosis and, thereby, endosomal signaling of several cell surface receptors including VEGF receptor-2 and TGFβ receptor in vascular endothelial cells (ECs). The Notch signaling cascade regulates many cellular processes including cell proliferation, cell fate specification and differentiation. In the present study, we explored a role of PI3K-C2α in Delta-like 4 (Dll4)-induced Notch signaling in ECs. We found that knockdown of PI3K-C2α inhibited Dll4-induced generation of the signaling molecule Notch intracellular domain 1 (NICD1) and the expression of Notch1 target genes including HEY1, HEY2 and NOTCH3 in ECs but not in vascular smooth muscle cells. PI3K-C2α knockdown did not inhibit Dll4-induced endocytosis of cell surface Notch1. In contrast, PI3K-C2α knockdown as well as clathrin heavy chain knockdown impaired endocytosis of Notch1-cleaving protease, γ-secretase complex, with the accumulation of Notch1 at the perinuclear endolysosomes. Pharmacological blockage of γ-secretase also induced the intracellular accumulation of Notch1. Taken together, we conclude that PI3K-C2α is required for the clathrin-mediated endocytosis of γ-secretase complex, which allows for the cleavage of endocytosed Notch1 by γ-secretase complex at the endolysosomes to generate NICD1 in ECs.

The Tumor Proteolytic Landscape: A Challenging Frontier in Cancer Diagnosis and Therapy

In recent decades, dysregulation of proteases and atypical proteolysis have become increasingly recognized as important hallmarks of cancer, driving community-wide efforts to explore the proteolytic landscape of oncologic disease. With more than 100 proteases currently associated with different aspects of cancer development and progression, there is a clear impetus to harness their potential in the context of oncology. Advances in the protease field have yielded technologies enabling sensitive protease detection in various settings, paving the way towards diagnostic profiling of disease-related protease activity patterns. Methods including activity-based probes and substrates, antibodies, and various nanosystems that generate reporter signals, i.e., for PET or MRI, after interaction with the target protease have shown potential for clinical translation. Nevertheless, these technologies are costly, not easily multiplexed, and require advanced imaging technologies. While the current clinical applications of protease-responsive technologies in oncologic settings are still limited, emerging technologies and protease sensors are poised to enable comprehensive exploration of the tumor proteolytic landscape as a diagnostic and therapeutic frontier. This review aims to give an overview of the most relevant classes of proteases as indicators for tumor diagnosis, current approaches to detect and monitor their activity in vivo, and associated therapeutic applications.