A small-molecule compound inhibits a collagen-specific molecular chaperone and could represent a potential remedy for fibrosis

Targeting HSP47 for cancer treatment

Heat shock protein 47 (HSP47) serves as an endoplasmic reticulum residing collagen-specific chaperone and plays an important role in collagen biosynthesis and structural assembly. HSP47 is encoded by the SERPINH1 gene, which is located on chromosome 11q13.5, one of the most frequently amplified regions in human cancers. The expression of HSP47 is regulated by multiple cellular factors, including cytokines, transcription factors, microRNAs, and circular RNAs. HSP47 is frequently upregulated in a variety of cancers and plays an important role in tumor progression. HSP47 promotes tumor stemness, angiogenesis, growth, epithelial-mesenchymal transition, and metastatic capacity. HSP47 also regulates the efficacy of tumor therapies, such as chemotherapy, radiotherapy, and immunotherapy. Inhibition of HSP47 expression has antitumor effects, suggesting that targeting HSP47 is a feasible strategy for cancer treatment. In this review, we highlight the function and expression of regulatory mechanisms of HSP47 in cancer progression and point out the potential development of therapeutic strategies in targeting HSP47 in the future.

Multiple aspects of matrix stiffness in cancer progression

The biophysical and biomechanical properties of the extracellular matrix (ECM) are crucial in the processes of cell differentiation and proliferation. However, it is unclear to what extent tumor cells are influenced by biomechanical and biophysical changes of the surrounding microenvironment and how this response varies between different tumor forms, and over the course of tumor progression. The entire ensemble of genes encoding the ECM associated proteins is called matrisome. In cancer, the ECM evolves to become highly dysregulated, rigid, and fibrotic, serving both pro-tumorigenic and anti-tumorigenic roles. Tumor desmoplasia is characterized by a dramatic increase of α-smooth muscle actin expressing fibroblast and the deposition of hard ECM containing collagen, fibronectin, proteoglycans, and hyaluronic acid and is common in many solid tumors. In this review, we described the role of inflammation and inflammatory cytokines, in desmoplastic matrix remodeling, tumor state transition driven by microenvironment forces and the signaling pathways in mechanotransduction as potential targeted therapies, focusing on the impact of qualitative and quantitative variations of the ECM on the regulation of tumor development, hypothesizing the presence of matrisome drivers, acting alongside the cell-intrinsic oncogenic drivers, in some stages of neoplastic progression and in some tumor contexts, such as pancreatic carcinoma, breast cancer, lung cancer and mesothelioma.

Targeting the HSP47-collagen axis inhibits brain metastasis by reversing M2 microglial polarization and restoring anti-tumor immunity

Brain metastases (BrMs) are the leading cause of death in patients with solid cancers. BrMs exhibit a highly immunosuppressive milieu and poor response to immunotherapies; however, the underlying mechanism remains largely unclear. Here, we show that upregulation of HSP47 in tumor cells drives metastatic colonization and outgrowth in the brain by creating an immunosuppressive microenvironment. HSP47-mediated collagen deposition in the metastatic niche promotes microglial polarization to the M2 phenotype via the α2β1 integrin/nuclear factor κB pathway, which upregulates the anti-inflammatory cytokines and represses CD8+ T cell anti-tumor responses. Depletion of microglia reverses HSP47-induced inactivation of CD8+ T cells and abolishes BrM. Col003, an inhibitor disrupting HSP47-collagen association restores an anti-tumor immunity and enhances the efficacy of anti-PD-L1 immunotherapy in BrM-bearing mice. Our study supports that HSP47 is a critical determinant of M2 microglial polarization and immunosuppression and that blocking the HSP47-collagen axis represents a promising therapeutic strategy against brain metastatic tumors.

Benzbromarone Induces Targeted Degradation of HSP47 Protein and Improves Hypertrophic Scar Formation

Fibrotic diseases are characterized by the abnormal accumulation of collagen in the extracellular matrix, leading to the functional impairment of various organs. In the skin, excessive collagen deposition manifests as hypertrophic scars and keloids, placing a substantial burden on patients and the healthcare system worldwide. HSP47 is essential for proper collagen assembly and contributes to fibrosis. However, identifying clinically applicable HSP47 inhibitors has been a major pharmaceutical challenge. In this study, we identified benzbromarone (BBR) as an HSP47 inhibitor for hypertrophic scarring treatment. BBR inhibited collagen production and secretion in fibroblasts from patients with keloid by binding to HSP47 and inhibiting the interaction between HSP47 and collagen. Interestingly, BBR not only inhibits HSP47 but also acts as a molecular glue degrader that promotes its proteasome-dependent degradation. Through these molecular mechanisms, BBR effectively reduced hypertrophic scarring in mini pigs and rats with burns and/or excisional skin damage. Thus, these findings suggest that BBR can be used to clinically treat hypertrophic scars and, more generally, fibrotic diseases.

HSP47 levels determine the degree of body adiposity

Adiposity varies among individuals with the influence of diverse physiological, pathological, environmental, hormonal, and genetic factors, but a unified molecular basis remains elusive. Here, we identify HSP47, a collagen-specific chaperone, as a key determinant of body adiposity. HSP47 expression is abundant in adipose tissue; increased with feeding, overeating, and obesity; decreased with fasting, exercise, calorie restriction, bariatric surgery, and cachexia; and correlated with fat mass, BMI, waist, and hip circumferences. Insulin and glucocorticoids, respectively, up- and down-regulate HSP47 expression. In humans, the increase of HSP47 gene expression by its intron or synonymous variants is associated with higher body adiposity traits. In mice, the adipose-specific knockout or pharmacological inhibition of HSP47 leads to lower body adiposity compared to the control. Mechanistically, HSP47 promotes collagen dynamics in the folding, secretion, and interaction with integrin, which activates FAK signaling and preserves PPARγ protein from proteasomal degradation, partly related to MDM2. The study highlights the significance of HSP47 in determining the amount of body fat individually and under various circumstances.

Effectiveness of conjunctival bleb scarring by knock-down of heat shock protein 47 in rat model

AIM

To evaluate the effectiveness of knock-down of heat shock protein 47 (HSP47) on conjunctival bleb scarring in a rat model and its possible mechanism.

METHODS

Male Sprague-Dawley rats were used for glaucoma filtration surgery (GFS) and were treated with either phosphate buffered solution, shControl, mitomycin C, or sh-HSP47 using a microsyringe immediately after GFS. The morphology of filtering blebs was observed postoperatively. The levels of HSP47 were analyzed at 2, 5, 8, and 11d after GFS via real-time quantitative polymerase chain reaction (PCR) and Western blot. The silencing effect of HSP47, the expression of collagen I and III, and the potential signaling pathways of HSP47 during scarification were explored 11d post GFS. The protein levels of transforming growth factor-β1 (TGF-β1), phospho-Smad2 (pSmad2), phospho-Smad3 (p-Smad3), and phospho-p38 (p-p38) were also analyzed using Western blot.

RESULTS

Sh-HSP47 treatment significantly prolonged the functional filtration bleb retention. The levels of HSP47 were increased significantly at 5, 8, and 11d postoperatively compared to the control group (P<0.05, P<0.01, and P<0.001). The levels of HSP47 protein at day 11 postoperatively were significantly down-regulated after HSP47 silencing using sh-HSP47 adenovirus transfection (P<0.01). Expression levels of collagen I and III within the blebs were significantly reduced in the absence of HSP47 (P<0.01). Moreover, the protein levels of TGF-β1, p-Smad2/3, and p-p38 were dramatically inhibited after treatment with sh-HSP47 (P<0.01).

CONCLUSION

The inhibitory effects of HSP47 knock-down on scarring after GFS have the potential to be an efficacious therapeutic option for the treatment of conjunctival bleb scarring.

HSP47: A Therapeutic Target in Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic lung disease characterized by a progressive decline in lung function and poor prognosis. The deposition of the extracellular matrix (ECM) by myofibroblasts contributes to the stiffening of lung tissue and impaired oxygen exchange in IPF. Type I collagen is the major ECM component and predominant collagen protein deposited in chronic fibrosis, suggesting that type I collagen could be a target of drugs for fibrosis treatment. Heat shock protein 47 (HSP47), encoded by the serpin peptidase inhibitor clade H, member 1 gene, is a stress-inducible collagen-binding protein. It is an endoplasmic reticulum-resident molecular chaperone essential for the correct folding of procollagen. HSP47 expression is increased in cellular and animal models of pulmonary fibrosis and correlates with pathological manifestations in human interstitial lung diseases. Various factors affect HSP47 expression directly or indirectly in pulmonary fibrosis models. Overall, understanding the relationship between HSP47 expression and pulmonary fibrosis may contribute to the development of novel therapeutic strategies.

Immobility-associated thromboprotection is conserved across mammalian species from bear to human

Venous thromboembolism (VTE) comprising deep venous thrombosis and pulmonary embolism is a major cause of morbidity and mortality. Short-term immobility-related conditions are a major risk factor for the development of VTE. Paradoxically, long-term immobilized free-ranging hibernating brown bears and paralyzed spinal cord injury (SCI) patients are protected from VTE. We aimed to identify mechanisms of immobility-associated VTE protection in a cross-species approach. Mass spectrometry-based proteomics revealed an antithrombotic signature in platelets of hibernating brown bears with heat shock protein 47 (HSP47) as the most substantially reduced protein. HSP47 down-regulation or ablation attenuated immune cell activation and neutrophil extracellular trap formation, contributing to thromboprotection in bears, SCI patients, and mice. This cross-species conserved platelet signature may give rise to antithrombotic therapeutics and prognostic markers beyond immobility-associated VTE.

Therapeutic Strategies to Overcome Fibrotic Barriers to Nanomedicine in the Pancreatic Tumor Microenvironment

Pancreatic cancer is notorious for its dismal prognosis. The enhanced permeability and retention (EPR) effect theory posits that nanomedicines (therapeutics in the size range of approximately 10-200 nm) selectively accumulate in tumors. Nanomedicine has thus been suggested to be the "magic bullet"-both effective and safe-to treat pancreatic cancer. However, the densely fibrotic tumor microenvironment of pancreatic cancer impedes nanomedicine delivery. The EPR effect is thus insufficient to achieve a significant therapeutic effect. Intratumoral fibrosis is chiefly driven by aberrantly activated fibroblasts and the extracellular matrix (ECM) components secreted. Fibroblast and ECM abnormalities offer various potential targets for therapeutic intervention. In this review, we detail the diverse strategies being tested to overcome the fibrotic barriers to nanomedicine in pancreatic cancer. Strategies that target the fibrotic tissue/process are discussed first, which are followed by strategies to optimize nanomedicine design. We provide an overview of how a deeper understanding, increasingly at single-cell resolution, of fibroblast biology is revealing the complex role of the fibrotic stroma in pancreatic cancer pathogenesis and consider the therapeutic implications. Finally, we discuss critical gaps in our understanding and how we might better formulate strategies to successfully overcome the fibrotic barriers in pancreatic cancer.

FOXL1+ Telocytes in mouse colon orchestrate extracellular matrix biodynamics and wound repair resolution

Recent studies have identified FoxL1⁺-telocytes (TC^FoxL1+) as key players in gut epithelial-mesenchymal interactions which can determine the colonic microenvironment. Bone morphogenetic protein signaling disruption in TC^FoxL1+ alters the physical and cellular microenvironment and leads to colon pathophysiology. This suggests a role for TC^FoxL1+ in stromagenesis, but it is hard to identify the specific contribution of TC^FoxL1+ when analyzing whole tissue profiling studies. We performed ex vivo deconstruction of control and BmpR1a^△FoxL1+ colon samples, isolated the mesenchyme-enriched fractions, and determined the protein composition of the in vivo extracellular matrix (ECM) to analyze microenvironment variation. Matrisomic analysis of mesenchyme fractions revealed modulations in ECM proteins with functions associated with innate immunity, epithelial wound healing, and the collagen network. These results show that TC^FoxL1+ is critical in orchestrating the biodynamics of the colon ECM. TC^FoxL1+ disfunction reprograms the gut's microenvironment and drives the intestinal epithelium toward colonic pathologies. SIGNIFICANCE: In this study, the method that was elected to isolate ECM proteins might not encompass the full extent of ECM proteins in a tissue, due to the protocol chosen, as this protocol by Naba et al., targets more the insoluble part of the matrisome and eliminates the more soluble components in the first steps. However, this ECM-enrichment strategy represents an improvement and interesting avenue to study ECM proteins in the colon compared to total tissue analysis with a background of abundant cellular protein. Thus, the matrisomic approach presented in this study, and its target validation delivered a broader evaluation of the matrix remodeling occurring in the colonic sub-epithelial mesenchyme of the BmpR1a^△FoxL1+ mouse model.

Platelets in the tumor microenvironment and their biological effects on cancer hallmarks

The interplay between platelets and tumors has long been studied. It has been widely accepted that platelets could promote tumor metastasis. However, the precise interactions between platelets and tumor cells have not been thoroughly investigated. Although platelets may play complex roles in multiple steps of tumor development, most studies focus on the platelets in the circulation of tumor patients. Platelets in the primary tumor microenvironment, in addition to platelets in the circulation during tumor cell dissemination, have recently been studied. Their effects on tumor biology are gradually figured out. According to updated cancer hallmarks, we reviewed the biological effects of platelets on tumors, including regulating tumor proliferation and growth, promoting cancer invasion and metastasis, inducing vasculature, avoiding immune destruction, and mediating tumor metabolism and inflammation.

High Levels of Heat Shock Protein 47 in the Aqueous Humor of Patients with Acute Primary Angle Closure

INTRODUCTION

Acute primary angle closure (APAC) is often characterized by acute elevation of intraocular pressure accompanied by severe ocular and systemic symptoms. Excessive collagen accumulation, which can be caused by upregulated heat shock protein 47 (HSP47) expression, can produce scarring in rat conjunctival blebs. Meanwhile, the presence of HSP47 in human aqueous humor and its levels are yet to be determined.

METHODS

We examined 32 consecutive patients with APAC and 16 age-matched participants without APAC scheduled for cataract surgery who were enrolled as a control group. Aqueous humor samples were collected from all subjects at the time of surgery and compared between the subjects with and without APAC.

RESULTS

The levels of HSP47 in the aqueous humor of patients with APAC (1,210.4 ± 450.2 pg/mL) were found to be significantly increased (p = 0.001) compared with those in the control group (863.4 ± 240.0 pg/mL). Notably, the levels of HSP47 negatively correlated with the age of patients with APAC (p = 0.023).

CONCLUSION

HSP47 was upregulated in the aqueous humor of patients with APAC and may play a role in scarring after trabeculectomy for APAC.

Collagen Remodeling along Cancer Progression Providing a Novel Opportunity for Cancer Diagnosis and Treatment

The extracellular matrix (ECM) is a significant factor in cancer progression. Collagens, as the main component of the ECM, are greatly remodeled alongside cancer development. More and more studies have confirmed that collagens changed from a barrier to providing assistance in cancer development. In this course, collagens cause remodeling alongside cancer progression, which in turn, promotes cancer development. The interaction between collagens and tumor cells is complex with biochemical and mechanical signals intervention through activating diverse signal pathways. As the mechanism gradually clears, it becomes a new target to find opportunities to diagnose and treat cancer. In this review, we investigated the process of collagen remodeling in cancer progression and discussed the interaction between collagens and cancer cells. Several typical effects associated with collagens were highlighted in the review, such as fibrillation in precancerous lesions, enhancing ECM stiffness, promoting angiogenesis, and guiding invasion. Then, the values of cancer diagnosis and prognosis were focused on. It is worth noting that several generated fragments in serum were reported to be able to be biomarkers for cancer diagnosis and prognosis, which is beneficial for clinic detection. At a glance, a variety of reported biomarkers were summarized. Many collagen-associated targets and drugs have been reported for cancer treatment in recent years. The new targets and related drugs were discussed in the review. The mass data were collected and classified by mechanism. Overall, the interaction of collagens and tumor cells is complicated, in which the mechanisms are not completely clear. A lot of collagen-associated biomarkers are excavated for cancer diagnosis. However, new therapeutic targets and related drugs are almost in clinical trials, with merely a few in clinical applications. So, more efforts are needed in collagens-associated studies and drug development for cancer research and treatment.

Collagen XI Alpha 1 Chain, a Novel Therapeutic Target for Cancer Treatment

The extracellular matrix (ECM) plays an important role in the progression of cancer. Collagen is the most abundant component in ECM, and is involved in the biological formation of cancer. Although type XI collagen is a minor fibrillar collagen, collagen XI alpha 1 chain (COL11A1) expression has been found to be upregulated in a variety of human cancers including colorectal, esophagus, glioma, gastric, head and neck, lung, ovarian, pancreatic, salivary gland, and renal cancers. High levels of COL11A1 usually predict poor prognosis, owing to its association with angiogenesis, invasion, and drug resistance in cancer. However, little is known about the specific mechanism through which COL11A1 regulates tumor progression. Here, we have organized and summarized recent developments regarding the interactions between COL11A1 and intracellular signaling pathways and selected therapeutic agents targeting COL11A1, as these indicate its potential as a target for treatment of cancers, especially epithelial ovarian cancer.

Role of collagen regulators in cancer treatment: A comprehensive review

Abstract:

Collagen is the most important structural protein and also a main component of extra-cellular matrix (ECM). It plays a role in tumor progression. Collagen can be regulated by altering it’s biosynthesis pathway through various signaling pathways, receptors and genes. Activity of cancer cells can also be regulated by other ECM components like metalloproteinases, hyaluronic acid, fibronectin and so on. Hypoxia is also one of the condition which leads to cancer progression by stimulating the expression of procollagen lysine as a collagen crosslinker, which increases the size of collagen fibres promoting cancer spread. The collagen content in cancerous cells leads to resistance in chemotherapy. So, to reduce this resistance, some of the collagen regulating therapies are introduced, which include inhibiting its biosynthesis, disturbing cancer cell signaling pathway, mediating ECM components and directly utilizing collagenase. This study is an effort to compile the strategies reported to control the collagen level and different collagen inhibitors reported so far. More research is needed in this area, growing understandings of collagen’s structural features and its role in cancer progression will aid in the advancement of newer chemotherapies.

Inflammation, oxidative stress and altered heat shock response in type 2 diabetes: the basis for new pharmacological and non-pharmacological interventions

Type 2 diabetes mellitus (DM2) is a chronic disease characterised by variable degrees of insulin resistance and impaired insulin secretion. Besides, several pieces of evidence have shown that chronic inflammation, oxidative stress, and 70 kDa heat shock proteins (HSP70) are strongly involved in DM2 and its complications, and various pharmacological and non-pharmacological treatment alternatives act in these processes/molecules to modulate them and ameliorate the disease. Besides, uncontrolled hyperglycaemia is related to several complications as diabetic retinopathy, neuropathy and hepatic, renal and cardiac complications. In this review, we address discuss the involvement of different inflammatory and pro-oxidant pathways related to DM2, and we described molecular targets modulated by therapeutics currently available to treat DM2.

Targeting extracellular matrix stiffness and mechanotransducers to improve cancer therapy

Cancer microenvironment is critical for tumorigenesis and cancer progression. The extracellular matrix (ECM) interacts with tumor and stromal cells to promote cancer cells proliferation, migration, invasion, angiogenesis and immune evasion. Both ECM itself and ECM stiffening-induced mechanical stimuli may activate cell membrane receptors and mechanosensors such as integrin, Piezo1 and TRPV4, thereby modulating the malignant phenotype of tumor and stromal cells. A better understanding of how ECM stiffness regulates tumor progression will contribute to the development of new therapeutics. The rapidly expanding evidence in this research area suggests that the regulators and effectors of ECM stiffness represent potential therapeutic targets for cancer. This review summarizes recent work on the regulation of ECM stiffness in cancer, the effects of ECM stiffness on tumor progression, cancer immunity and drug resistance. We also discuss the potential targets that may be druggable to intervene ECM stiffness and tumor progression. Based on these advances, future efforts can be made to develop more effective and safe drugs to interrupt ECM stiffness-induced oncogenic signaling, cancer progression and drug resistance.

Traf2 and NCK Interacting Kinase Is a Critical Regulator of Procollagen I Trafficking and Hepatic Fibrogenesis in Mice

Hepatic fibrosis is driven by deposition of matrix proteins following liver injury. Hepatic stellate cells (HSCs) drive fibrogenesis, producing matrix proteins, including procollagen I, which matures into collagen I following secretion. Disrupting intracellular procollagen processing and trafficking causes endoplasmic reticulum stress and stress-induced HSC apoptosis and thus is an attractive antifibrotic strategy. We designed an immunofluorescence-based small interfering RNA (siRNA) screen to identify procollagen I trafficking regulators, hypothesizing that these proteins could serve as antifibrotic targets. A targeted siRNA screen was performed using immunofluorescence to detect changes in intracellular procollagen I. Tumor necrosis factor receptor associated factor 2 and noncatalytic region of tyrosine kinase-interacting kinase (TNIK) was identified and interrogated in vitro and in vivo using the TNIK kinase inhibitor NCB-0846 or RNA interference-mediated knockdown. Our siRNA screen identified nine genes whose knockdown promoted procollagen I retention, including the serine/threonine kinase TNIK. Genetic deletion or pharmacologic inhibition of TNIK through the small molecule inhibitor NCB-0846 disrupted procollagen I trafficking and secretion without impacting procollagen I expression. To investigate the role of TNIK in liver fibrogenesis, we analyzed human and murine livers, finding elevated TNIK expression in human cirrhotic livers and increased TNIK expression and kinase activity in both fibrotic mouse livers and activated primary human HSCs. Finally, we tested whether inhibition of TNIK kinase activity could limit fibrogenesis in vivo. Mice receiving NCB-0846 displayed reduced CCl₄ -induced fibrogenesis compared to CCl₄ alone, although α-smooth muscle actin levels were unaltered. Conclusions: Our siRNA screen effectively identified TNIK as a key kinase involved in procollagen I trafficking in vitro and hepatic fibrogenesis in vivo.

Targeting Type I Collagen for Cancer Treatment

Collagen is the most abundant protein in animals. Interactions between tumor cells and collagen influence every step of tumor development. Type I collagen is the main fibrillar collagen in the extracellular matrix and is frequently up-regulated during tumorigenesis. The binding of type I collagen to its receptors on tumor cells promotes tumor cell proliferation, epithelial-mesenchymal transition, and metastasis. Type I collagen also regulates the efficacy of tumor therapies, such as chemotherapy, radiotherapy, and immunotherapy. Furthermore, type I collagen fragments are diagnostic markers of metastatic tumors and have prognostic value. Inhibition of type I collagen synthesis has been reported to have anti-tumor effects in animal models. However, collagen has also been shown to possess anti-tumor activity. Therefore, the roles that type I collagen plays in tumor biology are complex and tumor type-dependent. In this review, we discuss the expression and regulation of synthesis of type I collagen, as well as the role up-regulated type I collagen plays in various stages of cancer progression. We also discuss the role of collagen in tumor therapy. Finally, we highlight several recent approaches targeting type I collagen for cancer treatment. This article is protected by copyright. All rights reserved.

Hsp47 Inhibitor Col003 Attenuates Collagen-Induced Platelet Activation and Cerebral Ischemic-Reperfusion Injury in Rats

Ischemic stroke is a major type of stroke worldwide currently without effective treatment, although antiplatelet therapy is an existing option for it. In previous studies, heat shock protein 47 (Hsp47) was found to be expressed on the surface of human and mice platelets and to strengthen the interaction between platelets and collagen. In recent years, Col003 was discovered to inhibit the interaction of Hsp47 with collagen. We evaluated whether the Hsp47 inhibitor Col003 is a promising therapeutic agent for ischemic stroke. Here, we first verified that Hsp47 is also expressed on the surface of rat platelets, and its inhibitor Col003 significantly inhibited thrombus formation in the FeCl₃-induced rat carotid arterial thrombus model. Both Col003 and clopidogrel did not alter the bleeding time or coagulation parameters, while aspirin increased the tail-bleeding time (p < 0.05). The low cytotoxicity level of Col003 to rat platelets and human liver cells was similar to those of aspirin and clopidogrel. Col003 inhibited collagen-induced platelet aggregation, adhesion, [Ca²⁺]_i mobilization, P-selectin expression, reactive oxygen species production and the downstream signal pathway of collagen receptors. The results of the middle cerebral artery occlusion model indicated that Col003 has a protective effect against cerebral ischemic-reperfusion injury in rats. The Hsp47 inhibitor Col003 exerted antiplatelet effect and protective effect against brain damage induced by ischemic stroke through the inhibition of glycoprotein VI (GPVI)and mitogen-activated protein kinase (MAPK) signaling events, which might yield a new antiplatelet agent and strategy to treat ischemic stroke.

Notch1 signaling enhances collagen expression and fibrosis in mouse uterus

Fibrosis is a pathological process characterized by abnormal activation of fibroblasts with increased synthesis of extracellular matrix components, including collagens. It may lead to loss of proper tissue architecture and organ function in clinical diseases such as systemic sclerosis and liver fibrosis. Excess accumulation of collagens is considered the primary indicator of fibrosis. Notch signaling has been reported to be involved in the fibrosis of many different organs, including the liver. Our previous study showed that the uterine-specific over-activation of canonical Notch1 signaling in the mouse uterus (Pgr^cre/+ Rosa26^N1ICD/+ , OEx) results in complete infertility as a consequence of multiple developmental and physiological defects, together with increased collagen accumulation evidenced by Masson's staining. In this study, we further detected expressions of all 44 collagen genes in these Notch1 gain-of-function transgenic mice and found that 18 collagens have been largely affected. In another aspect, using an intrauterine adhesion model (IUA), we mimicked fibrosis in the mouse uterine. The results suggested that Notch receptors were upregulated only 3 days after induction, and most of the fibril-forming collagen began to upregulate 6 days after the surgery. Furthermore, when induced IUA in the N1ICD-OEx mice, the expression of collagens and fibrosis levels were significantly enhanced. At last, as a Notch signaling inhibitor, the γ-secretase inhibitor N-[N-(3,5-difl uorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (DAPT) pretreatment could alleviate the expression of collagens and the symptoms of fibrosis. These results demonstrate that Notch signaling may play a role in upregulating collagens expression in endometrial fibrosis and might be a potential target of fibrosis therapy in the endometrium.

Identification of HSP47 Binding Site on Native Collagen and Its Implications for the Development of HSP47 Inhibitors

HSP47 (heat shock protein 47) is a collagen-specific molecular chaperone that is essential for procollagen folding and function. Previous studies have shown that HSP47 binding requires a critical Arg residue at the Y position of the (Gly-Xaa-Yaa) repeats of collagen; however, the exact binding sites of HSP47 on native collagens are not fully defined. To address this, we mapped the HSP47 binding sites on collagens through an ELISA binding assay using collagen toolkits, synthetic collagen peptides covering the entire amino acid sequences of collagen types II and III assembled in triple-helical conformation. Our results showed that HSP47 binds to only a few of the GXR motifs in collagen, with most of the HSP47 binding sites identified located near the N-terminal part of the triple-helical region. Molecular modelling and binding energy calculation indicated that residues flanking the key Arg in the collagen sequence also play an important role in defining the high-affinity HSP47 binding site of collagen. Based on this binding mode of HSP47 to collagen, virtual screening targeting both the Arg binding site and its neighboring area on the HSP47 surface, and a subsequent bioassay, we identified two novel compounds with blocking activity towards HSP47 binding of collagen. Overall, our study revealed the native HSP47 binding sites on collagen and provided novel information for the design of small-molecule inhibitors of HSP47.

Screening of Inhibitors Targeting Heat Shock Protein 47 Involved in the Development of Idiopathic Pulmonary Fibrosis

Heat shock protein 47 (HSP47), a collagen-specific molecular chaperone, is causally related to fibrotic diseases, including idiopathic pulmonary fibrosis. The identification of Compounds that interfere with the HSP47-collagen interaction is essential for the development of relevant therapeutics. Herein, we prepared human HSP47 as a soluble fusion protein expressed in E. coli and established an assay system for HSP47 inhibitor screening. We screened a natural and synthetic Compound library established at Nagasaki University. Among 1023 Compounds, 13 exhibited inhibitory activity against human HSP47, of which three inhibited its function in a dose-dependent manner. Epigallocatechin-3-O-gallate, one of these three Compounds, is a typical polyphenol Compound derived from tea leaves. Structurally related Compounds were synthesized and examined for their activity, revealing a hydroxyl group at A-ring position 5 as important for its activity. The present findings provide valuable insight for the development of natural product-derived therapeutics for fibrotic diseases, including idiopathic pulmonary fibrosis.

Quality Control of Procollagen in Cells

Collagen is the most abundant protein in mammals. A unique feature of collagen is its triple-helical structure formed by the Gly-Xaa-Yaa repeats. Three single chains of procollagen make a trimer, and the triple-helical structure is then folded in the endoplasmic reticulum (ER). This unique structure is essential for collagen's functions in vivo, including imparting bone strength, allowing signal transduction, and forming basement membranes. The triple-helical structure of procollagen is stabilized by posttranslational modifications and intermolecular interactions, but collagen is labile even at normal body temperature. Heat shock protein 47 (Hsp47) is a collagen-specific molecular chaperone residing in the ER that plays a pivotal role in collagen biosynthesis and quality control of procollagen in the ER. Mutations that affect the triple-helical structure or result in loss of Hsp47 activity cause the destabilization of procollagen, which is then degraded by autophagy. In this review, we present the current state of the field regarding quality control of procollagen.

Collagen Type XI Alpha 1 (COL11A1): A Novel Biomarker and a Key Player in Cancer

Collagen type XI alpha 1 (COL11A1), one of the three alpha chains of type XI collagen, is crucial for bone development and collagen fiber assembly. Interestingly, COL11A1 expression is increased in several cancers and high levels of COL11A1 are often associated with poor survival, chemoresistance, and recurrence. This review will discuss the recent discoveries in the biological functions of COL11A1 in cancer. COL11A1 is predominantly expressed and secreted by a subset of cancer-associated fibroblasts, modulating tumor-stroma interaction and mechanical properties of extracellular matrix. COL11A1 also promotes cancer cell migration, metastasis, and therapy resistance by activating pro-survival pathways and modulating tumor metabolic phenotype. Several inhibitors that are currently being tested in clinical trials for cancer or used in clinic for other diseases, can be potentially used to target COL11A1 signaling. Collectively, this review underscores the role of COL11A1 as a promising biomarker and a key player in cancer.

Silencing Heat Shock Protein 47 (HSP47) in Fibrogenic Precision-Cut Lung Slices: A Surprising Lack of Effects on Fibrogenesis?

Idiopathic pulmonary fibrosis (IPF) is a chronic disease that is characterized by the excessive deposition of scar tissue in the lungs. As currently available treatments are unable to restore lung function in patients, there is an urgent medical need for more effective drugs. Developing such drugs, however, is challenging because IPF has a complex pathogenesis. Emerging evidence indicates that heat shock protein 47 (HSP47), which is encoded by the gene Serpinh1, may be a suitable therapeutic target as it is required for collagen synthesis. Pharmacological inhibition or knockdown of HSP47 could therefore be a promising approach to treat fibrosis. The objective of this study was to assess the therapeutic potential of Serpinh1-targeting small interfering RNA (siRNA) in fibrogenic precision-cut lung slices prepared from murine tissue. To enhance fibrogenesis, slices were cultured for up to 144 h with transforming growth factor β1. Self-deliverable siRNA was used to knockdown mRNA and protein expression, without affecting the viability and morphology of slices. After silencing HSP47, only the secretion of fibronectin was reduced while other aspects of fibrogenesis remained unaffected (e.g., myofibroblast differentiation as well as collagen secretion and deposition). These observations are surprising as others have shown that Serpinh1-targeting siRNA suppressed collagen deposition in animals. Further studies are therefore warranted to elucidate downstream effects on fibrosis upon silencing HSP47.

HSP47: a potential target for fibrotic diseases and implications for therapy

Introduction: Chronic fibrotic disorders are challenging clinical problems. The major challenge is the identification of specific targets expressed selectively in fibrotic tissues. Collagen accumulation is the hallmark fibrosis. HSP47 is a collagen-specific chaperon with critical role in collagen folding. This review discusses the anti-fibrotic potential of HSP47. Areas covered: This review compiles data retrieved from the PubMed database with keywords 'HSP47+fibrosis' from 01/2005 to 06/2020. We examined 1) collagen biology and its role in fibrotic diseases, 2) HSP47 role in fibrosis, 3) HSP47 inhibition strategies and 4) clinical investigations. The identification of the HSP47-collagen binding site led to the development of methods to screen HSP47 inhibitors with anti-fibrotic potential. Specific in vivo  delivery systems of HSP47 siRNA to fibrotic tissue reduced collagen production/secretion associated with fibrosis inhibition in preclinical models. This strategy is about to be tested in clinical trials. Expert opinion: As a collagen-specific chaperon, HSP47 is a promising therapeutic target in fibrosis. Preclinical models have shown encouraging anti-fibrotic results. Anti-HSP47 strategies need to be further evaluated in clinical trials. The increase in circulating-HSP47 in lung fibrosis patients highlights the potential of HSP47 as a noninvasive biomarker and may represent an important step toward personalized medicine in fibrotic disorders.

Small-molecule modulators of serine protease inhibitor proteins (serpins)

Serine protease inhibitors (serpins) are a large family of proteins that regulate and control crucial physiological processes, such as inflammation, coagulation, thrombosis and thrombolysis, and immune responses. The extraordinary impact that these proteins have on numerous crucial pathways makes them an attractive target for drug discovery. In this review, we discuss recent advances in research on small-molecule modulators of serpins, examine their mode of action, analyse the structural data from crystallised protein-ligand complexes, and highlight the potential obstacles and possible therapeutic perspectives. The application of in silico methods for rational drug discovery is also summarised. In addition, we stress the need for continued research in this field.

Danger signals in liver injury and restoration of homeostasis

Damage-associated molecular patterns are signalling molecules involved in inflammatory responses and restoration of homeostasis. Chronic release of these molecules can also promote inflammation in the context of liver disease. Herein, we provide a comprehensive summary of the role of damage-associated molecular patterns as danger signals in liver injury. We consider the role of reactive oxygen species and reactive nitrogen species as inducers of damage-associated molecular patterns, as well as how specific damage-associated molecular patterns participate in the pathogenesis of chronic liver diseases such as alcohol-related liver disease, non-alcoholic steatohepatitis, liver fibrosis and liver cancer. In addition, we discuss the role of damage-associated molecular patterns in ischaemia reperfusion injury and liver transplantation and highlight current studies in which blockade of specific damage-associated molecular patterns has proven beneficial in humans and mice.

Intestinal stenosis in Crohn's disease shows a generalized upregulation of genes involved in collagen metabolism and recognition that could serve as novel anti-fibrotic drug targets

BACKGROUND AND AIMS

Crohn's disease (CD) can be complicated by intestinal fibrosis. Pharmacological therapies against intestinal fibrosis are not available. The aim of this study was to determine whether pathways involved in collagen metabolism are upregulated in intestinal fibrosis, and to discuss which drugs might be suitable to inhibit excessive extracellular matrix formation targeting these pathways.

METHODS

Human fibrotic and non-fibrotic terminal ileum was obtained from patients with CD undergoing ileocecal resection due to stenosis. Genes involved in collagen metabolism were analyzed using a microfluidic low-density TaqMan array. A literature search was performed to find potential anti-fibrotic drugs that target proteins/enzymes involved in collagen synthesis, its degradation and its recognition.

RESULTS

mRNA expression of collagen type I (COL1A1, 0.76 ± 0.28 versus 37.82 ± 49.85, p = 0.02) and III (COL3A1, 2.01 ± 2.61 versus 68.65 ± 84.07, p = 0.02) was increased in fibrotic CD compared with non-fibrotic CD. mRNA expression of proteins involved in both intra- and extracellular post-translational modification of collagens (prolyl- and lysyl hydroxylases, lysyl oxidases, chaperones), collagen-degrading enzymes (MMPs and cathepsin-K), and collagen receptors were upregulated in the fibrosis-affected part. A literature search on the upregulated genes revealed several potential anti-fibrotic drugs.

CONCLUSION

Expression of genes involved in collagen metabolism in intestinal fibrosis affected terminal ileum of patients with CD reveals a plethora of drug targets. Inhibition of post-translational modification and altering collagen metabolism might attenuate fibrosis formation in the intestine in CD. Which compound has the highest potential depends on a combination anti-fibrotic efficacy and safety, especially since some of the enzymes play key roles in the physiology of collagen.

Exogenous supply of Hsp47 triggers fibrillar collagen deposition in skin cell cultures in vitro

Background

Collagen is a structural protein that provides mechanical stability and defined architectures to skin. In collagen-based skin disorders this stability is lost, either due to mutations in collagens or in the chaperones involved in collagen assembly. This leads to chronic wounds, skin fragility, and blistering. Existing approaches to treat such conditions rely on administration of small molecules to simulate collagen production, like 4-phenylbutyrate (4-PBA) or growth factors like TGF-β. However, these molecules are not specific for collagen synthesis, and result in unsolicited side effects. Hsp47 is a collagen-specific chaperone with a major role in collagen biosynthesis. Expression levels of Hsp47 correlate with collagen deposition. This article explores the stimulation of collagen deposition by exogenously supplied Hsp47 (collagen specific chaperone) to skin cells, including specific collagen subtypes quantification.

Results

Here we quantify the collagen deposition level and the types of deposited collagens after Hsp47 stimulation in different in vitro cultures of cells from human skin tissue (fibroblasts NHDF, keratinocytes HaCat and endothelial cells HDMEC) and mouse fibroblasts (L929 and MEF). We find upregulated deposition of fibrillar collagen subtypes I, III and V after Hsp47 delivery. Network collagen IV deposition was enhanced in HaCat and HDMECs, while fibril-associated collagen XII was not affected by the increased intracellular Hsp47 levels. The deposition levels of fibrillar collagen were cell-dependent i.e. Hsp47-stimulated fibroblasts deposited significantly higher amount of fibrillar collagen than Hsp47-stimulated HaCat and HDMECs.

Conclusions

A 3-fold enhancement of collagen deposition was observed in fibroblasts upon repeated dosage of Hsp47 within the first 6 days of culture. Our results provide fundamental understanding towards the idea of using Hsp47 as therapeutic protein to treat collagen disorders.

SERPINH1 regulates EMT and gastric cancer metastasis via the Wnt/β-catenin signaling pathway

In this study, we investigated the role of SERPINH1 in gastric cancer (GC) progression. GC patient tissues show significantly higher SERPINH1 mRNA and protein levels than normal gastric mucosal tissues. GC patients with high SERPINH1 expression are associated with lymph node metastasis and poor prognosis. SERPINH1 mRNA levels negatively correlate with E-cadherin mRNA levels and positively correlate with levels of N-cadherin, MMP2, and MMP9 mRNA levels. This suggests SERPINH1 regulates epithelial to mesenchymal transition (EMT). SERPINH1 expression was significantly higher in the HGC-27, AGS, MGC-803, and SGC-7901 GC cell lines than in the GES-1 normal gastric mucosal cell line. In SERPINH1-silenced SGC-7901 cells, survival, colony formation, migration and invasion were all reduced, whereas they were all enhanced in SERPINH1-overexpressing MGC-803 cells. Levels of WNT/β-catenin signaling pathway proteins, including β-catenin, Wnt2, GSK-3β, p-GSK-3β, NF-κB P65, Snail1, Slug and TWIST, were all reduced in SERPINH1-silenced SGC-7901 cells, and increased in the SERPINH1-overexpressing MGC-803 cells. Inhibition of SERPINH1 protein using Co1003 significantly decreased survival, invasion, and migration of GC cells. SERPINH1 thus appears to regulate EMT and GC progression via the Wnt/β-catenin pathway, making SERPINH1 a potential prognostic biomarker and therapeutic target in GC patients.

Hsp47 promotes cancer metastasis by enhancing collagen-dependent cancer cell-platelet interaction

Increased expression of extracellular matrix (ECM) proteins in circulating tumor cells (CTCs) suggests potential function of cancer cell-produced ECM in initiation of cancer cell colonization. Here, we showed that collagen and heat shock protein 47 (Hsp47), a chaperone facilitating collagen secretion and deposition, were highly expressed during the epithelial-mesenchymal transition (EMT) and in CTCs. Hsp47 expression induced mesenchymal phenotypes in mammary epithelial cells (MECs), enhanced platelet recruitment, and promoted lung retention and colonization of cancer cells. Platelet depletion in vivo abolished Hsp47-induced cancer cell retention in the lung, suggesting that Hsp47 promotes cancer cell colonization by enhancing cancer cell-platelet interaction. Using rescue experiments and functional blocking antibodies, we identified type I collagen as the key mediator of Hsp47-induced cancer cell-platelet interaction. We also found that Hsp47-dependent collagen deposition and platelet recruitment facilitated cancer cell clustering and extravasation in vitro. By analyzing DNA/RNA sequencing data generated from human breast cancer tissues, we showed that gene amplification and increased expression of Hsp47 were associated with cancer metastasis. These results suggest that targeting the Hsp47/collagen axis is a promising strategy to block cancer cell-platelet interaction and cancer colonization in secondary organs.

Structure-Activity Relationship Study on Col-003, a Protein-Protein Interaction Inhibitor between Collagen and Hsp47

This study demonstrates the structure-activity relationship of Col-003, a potent collagen-heat-shock protein 47 (Hsp47) interaction inhibitor. Col-003 analogues were successfully synthesized by Pd(0)-catalyzed cross-coupling reactions of 5-bromosalicylaldehyde derivatives with alkyl-metal species, and the inhibitory activities of the synthetic analogues were evaluated using surface plasmon resonance analysis (BIAcore). We succeeded in discovering two potent inhibitors that showed 85 and 81% inhibition at a concentration of 1.9 µM against the collagen-Hsp47 interaction. This indicates that elongation of an alkyl linker between two aromatic rings could considerably improve inhibitory activity due to the adjustment of a pendant phenyl moiety to an appropriate position, in addition to the hydrophobic interaction with an alkyl linker moiety.

A BRET-based assay reveals collagen-Hsp47 interaction dynamics in the endoplasmic reticulum and small-molecule inhibition of this interaction

Molecular chaperones perform pivotal roles in proteostasis by engaging in protein–protein interactions (PPIs). The collagen-specific molecular chaperone Hsp47 (heat shock protein 47) interacts with procollagen in the endoplasmic reticulum (ER) and plays crucial roles in collagen synthesis. PPIs between Hsp47 and collagen could offer a therapeutic target for fibrosis, which is characterized by abnormal collagen accumulation in the extracellular matrix of fibrotic organs. Herein, we established a bioluminescence resonance energy transfer (BRET) system for assessing Hsp47–collagen interaction dynamics within the ER. After optimization and validation of the method, we could demonstrate inhibition of the interaction between Hsp47 and collagen by a small molecule (Col003) in the ER. Using the BRET system, we also found that Hsp47 interacts not only with the Gly-Pro-Arg motif but also weakly with Gly-Pro-Hyp motifs of triple-helical collagen in cells. Moreover, we found that the serpin loop of Hsp47 (SerpinH1) contributes to its binding to collagen. We propose that the method developed here can provide valuable information on PPIs between Hsp47 and collagen and on the effects of PPI inhibitors important for the management of fibrotic disorders.

Chronic restraint stress induces esophageal fibrosis with enhanced oxidative stress in a murine model

Although the underlying mechanism of stress remains unknown, it has been associated with the pathophysiology of gastroesophageal reflux diseases, the development of which appear to be accelerated by oxidative stress and fibrosis. The aim of the current study was to investigate the effect of chronic restraint stress on esophageal oxidative stress and fibrosis, as well as the impact of oxidative stress in a murine model whereby 8-week old C57BL/6J male mice were subjected to intermittent chronic restraint stress for a two-week period. The current study demonstrated that chronic restraint stress significantly reduced the body weight of mice compared with the control group. Although chronic restraint stress did not significantly alter the levels of triglycerides or cholesterol, free fatty acid concentration was significantly increased compared with the control group. Furthermore, chronic restraint stress significantly upregulated the expression levels of several fibrotic biomarkers including collagen type I, transforming growth factor β-1, α-smooth muscle actin and SMAD-3 compared with the control group. In addition, the expression levels of the reactive oxygen species (ROS) NADPH oxidase-4 and malondialdehyde were significantly increased, while the expression levels of nuclear factor erythroid 2-related factor 2 and heme oxygenase-1 were significantly decreased in esophageal tissue from mice in the chronic restraint stress group compared with the control group. In conclusion, chronic restraint stress may induce esophageal fibrosis by accumulating ROS and increasing fibrotic gene expression in a murine model.

Photoactivatable Hsp47: A Tool to Regulate Collagen Secretion and Assembly

Collagen is the most abundant structural protein in mammals and is crucial for the mechanical integrity of tissues. Hsp47, an endoplasmic reticulum resident collagen-specific chaperone, is involved in collagen biosynthesis and plays a fundamental role in the folding, stability, and intracellular transport of procollagen triple helices. This work reports on a photoactivatable derivative of Hsp47 that allows regulation of collagen biosynthesis within mammalian cells using light. Photoactivatable Hsp47 contains a non-natural light-responsive tyrosine (o-nitro benzyl tyrosine (ONBY)) at Tyr383 position of the protein sequence. This mutation renders Hsp47 inactive toward collagen binding. The inactive, photoactivatable protein is easily uptaken by cells within a few minutes of incubation, and accumulated at the endoplasmic reticulum via retrograde KDEL receptor-mediated uptake. Upon light exposure, the photoactivatable Hsp47 turns into functional Hsp47 in situ. The increased intracellular concentration of Hsp47 results in stimulated secretion of collagen. The ability to promote collagen synthesis on demand, with spatiotemporal resolution, and in diseased state cells is demonstrated in vitro. It is envisioned that photoactivatable Hsp47 allows unprecedented fundamental studies of collagen biosynthesis, matrix biology, and inspires new therapeutic concepts in biomedicine and tissue regeneration.

Targeting defective proteostasis in the collagenopathies

The collagenopathies are a diverse group of diseases caused primarily by mutations in collagen genes. The resulting disruptions in collagen biogenesis can impair development, cause cellular dysfunction, and severely impact connective tissues. Most existing treatment options only address patient symptoms. Yet, while the disease-causing genes and proteins themselves are difficult to target, increasing evidence suggests that resculpting the intracellular proteostasis network, meaning the machineries responsible for producing and ensuring the integrity of collagen, could provide substantial benefit. We present a proteostasis-focused perspective on the collagenopathies, emphasizing progress toward understanding how mechanisms of collagen proteostasis are disrupted in disease. In parallel, we highlight recent advances in small molecule approaches to tune endoplasmic reticulum proteostasis that may prove useful in these disorders.

Roles of the endoplasmic reticulum-resident, collagen-specific molecular chaperone Hsp47 in vertebrate cells and human disease

Heat shock protein 47 (Hsp47) is an endoplasmic reticulum (ER)-resident molecular chaperone essential for correct folding of procollagen in mammalian cells. In this Review, we discuss the role and function of Hsp47 in vertebrate cells and its role in connective tissue disorders. Hsp47 binds to collagenous (Gly-Xaa-Arg) repeats within triple-helical procollagen in the ER and can prevent its local unfolding or aggregate formation, resulting in accelerating triple-helix formation of procollagen. Hsp47 pH-dependently dissociates from procollagen in the cis-Golgi or ER-Golgi intermediate compartment and is then transported back to the ER. Although Hsp47 belongs to the serine protease inhibitor (serpin) superfamily, it does not possess serine protease inhibitory activity. Whereas general molecular chaperones such as Hsp70 and Hsp90 exhibit broad substrate specificity, Hsp47 has narrower specificity mainly for procollagens. However, other Hsp47-interacting proteins have been recently reported, suggesting a much broader role for Hsp47 in the cell that warrants further investigation. Other ER-resident stress proteins, such as binding immunoglobulin protein (BiP), are induced by ER stress, whereas Hsp47 is induced only by heat shock. Constitutive expression of Hsp47 is always correlated with expression of various collagen types, and disruption of the Hsp47 gene in mice causes embryonic lethality due to impaired basement membrane and collagen fibril formation. Increased Hsp47 expression is associated with collagen-related disorders such as fibrosis, characterized by abnormal collagen accumulation, highlighting Hsp47's potential as a clinically relevant therapeutic target.

Development of a Gill Assay Library for Ecological Proteomics of Threespine Sticklebacks (Gasterosteus aculeatus)

A data-independent acquisition (DIA) assay library for quantitative analyses of proteome dynamics has been developed for gills of threespine sticklebacks (Gasterosteus aculeatus). A raw spectral library was generated by data-dependent acquisition (DDA) and annotation of tryptic peptides to MSMS spectra and protein database identifiers. The assay library was constructed from the raw spectral library by removal of low-quality, ambiguous, and low-signal peptides. Only unique proteins represented by at least two peptides are included in the assay library, which consists of 1506 proteins, 5074 peptides, 5104 precursors, and 25,322 transitions. This assay library was used with DIA data to identify biochemical differences in gill proteomes of four populations representing different eco- and morpho-types of threespine sticklebacks. The assay library revealed unique and reproducible proteome signatures. Warm-adapted, low-plated, brackish-water fish from Laguna de la Bocana del Rosario (Mexico) show elevated HSP47, extracellular matrix, and innate immunity proteins whereas several immunoglobulins, interferon-induced proteins, ubiquitins, proteolytic enzymes, and nucleic acid remodeling proteins are reduced. Fully-plated, brackish-water fish from Westchester Lagoon (Alaska) display elevated ion regulation, GTPase signaling, and contractile cytoskeleton proteins, altered abundances of many ribosomal, calcium signaling and immunity proteins, and depleted transcriptional regulators and metabolic enzymes. Low-plated freshwater fish from Lake Solano (California) have elevated inflammasomes and proteolytic proteins whereas several iron containing and ion regulatory proteins are reduced. Gills of fully-plated, marine fish from Bodega Harbor (California) have elevated oxidative metabolism enzymes and reduced transglutaminase 2, collagens, and clathrin heavy chains. These distinct proteome signatures represent targets for testing ecological and evolutionary influences on molecular mechanisms of gill function in threespine sticklebacks. Furthermore, the gill assay library represents a model for other tissues and paves the way for accurate and reproducible network analyses of environmental context-dependent proteome dynamics in complex organisms.

The heat shock protein 47 as a potential biomarker and a therapeutic agent in cancer research

Heat shock protein 47 (HSP47) is an important chaperone required for the correct folding and secretion of collagen. Several studies revealed that HSP47 has a role in numerous steps of collagen synthesis, preventing procollagen aggregation and inducing hydroxylation of proline and lysine residues. HSP47 is encoded by the SERPINH1 gene, which is located on chromosome 11q13.5, one of the most frequently amplified regions in human cancer. The altered expression levels of HSP47 have been correlated with several types of cancer, such as cervical, breast, pancreatic and gastric cancers. Studies have shown that HSP47 promotes tumor angiogenesis, growth, migration and metastatic capacity. In this review, we highlight the fundamental aspects of the interaction between HSP47 and collagen and the recent discoveries of the role of this chaperone in different types of malignant neoplasias. We also discuss recent treatments using HSP47 as a therapeutic target, and present evidences that HSP47 is an essential protein for cancer biology and a potential molecular target for chemotherapy.

Heat shock protein 47 as indispensible participant in liver fibrosis: Possible protective effect of lactoferrin

Lactoferrin (LF) was previously suggested to have a protective effect against liver fibrosis by preventing hepatic stellate cells (HSCs) activation. The effect of LF on heat shock protein 47 (HSP47) has not yet been studied so this study was designed to investigate LF effect on HSP47 as a potential target for management of liver fibrosis and comparing it with silymarin (SM) in a thioacetamide (TAA)-induced liver fibrosis model. Rats were divided into four groups; normal control, TAA (TAA-treated), LF (LF + TAA-treated), and SM (SM + TAA-treated). After 6 weeks, both LF and SM improved the grade of cirrhosis, reduced collagen fibers deposition, inactivated HSCs, significantly decreased elevated liver enzymes, HSP47, hydroxyproline content, transforming growth factor-beta 1, matrix metalloproteinase-2, 8-hydroxydeoxyguanosine, malondialdehyde, nitric oxide levels and the percentage of alpha smooth muscle actin positive HSCs compared with TAA group. Moreover, LF significantly increased the total antioxidant capacity compared with TAA group. It could be concluded that LF is a promising antifibrotic drug and could be considered as one of the HSP47 inhibitors but SM is still more potent. © 2018 IUBMB Life, 70(8):795-805, 2018.

A High-Throughput Assay for Collagen Secretion Suggests an Unanticipated Role for Hsp90 in Collagen Production

Collagen overproduction is a feature of fibrosis and cancer, while insufficient deposition of functional collagen molecules and/or the secretion of malformed collagen is common in genetic disorders like osteogenesis imperfecta. Collagen secretion is an appealing therapeutic target in these and other diseases, as secretion directly connects intracellular biosynthesis to collagen deposition and biological function in the extracellular matrix. However, small molecule and biological methods to tune collagen secretion are severely lacking. Their discovery could prove useful not only in the treatment of disease, but also in providing tools for better elucidating mechanisms of collagen biosynthesis. We developed a cell-based, high-throughput luminescent assay of collagen type I secretion and used it to screen for small molecules that selectively enhance or inhibit that process. Among several validated hits, the Hsp90 inhibitor 17-allylaminogeldanamycin (17-AAG) robustly decreases the secretion of collagen-I by our model cell line and by human primary cells. In these systems, 17-AAG and other pan-isoform Hsp90 inhibitors reduce collagen-I secretion post-translationally and are not global inhibitors of protein secretion. Surprisingly, the consequences of Hsp90 inhibitors cannot be attributed to inhibition of the endoplasmic reticulum's Hsp90 isoform, Grp94. Instead, collagen-I secretion likely depends on the activity of cytosolic Hsp90 chaperones, even though such chaperones cannot directly engage nascent collagen molecules. Our results highlight the value of a cell-based high-throughput screen for selective modulators of collagen secretion and suggest an unanticipated role for cytosolic Hsp90 in collagen secretion.

Activating and Repressing IRE1α: The Hsp47 and BiP Tug of War

In this issue of Molecular Cell, Sepulveda et al. (2018) discovered an interesting role of Hsp47 in regulating the unfolded protein response (UPR) wherein Hsp47 binds to IRE1α and displaces BiP, thereby activating the IRE1α arm of the UPR pathway by a previously undetermined mechanism.

Heat Shock Proteins in Vascular Diabetic Complications: Review and Future Perspective

Heat shock proteins (HSPs) are a large family of proteins highly conserved throughout evolution because of their unique cytoprotective properties. Besides assisting protein refolding and regulating proteostasis under stressful conditions, HSPs also play an important role in protecting cells from oxidative stress, inflammation, and apoptosis. Therefore, HSPs are crucial in counteracting the deleterious effects of hyperglycemia in target organs of diabetes vascular complications. Changes in HSP expression have been demonstrated in diabetic complications and functionally related to hyperglycemia-induced cell injury. Moreover, associations between diabetic complications and altered circulating levels of both HSPs and anti-HSPs have been shown in clinical studies. HSPs thus represent an exciting therapeutic opportunity and might also be valuable as clinical biomarkers. However, this field of research is still in its infancy and further studies in both experimental diabetes and humans are required to gain a full understanding of HSP relevance. In this review, we summarize current knowledge and discuss future perspective.