Basic mechanism of mobilizing cell movement during invasion of glioblastoma and target selection of targeted therapy

BACKGROUND

Glioblastoma (GBM), also known as glioblastoma multiforme, is a rapidly growing and highly invasive malignant tumor. Due to the inability to clearly distinguish between glioblastoma and normal tissue, surgery cannot achieve safe resection, often leading to poor patient prognosis and inevitable tumor recurrence. According to previous studies, GBM invasion is related to intercellular adhesion, matrix degradation, extracellular matrix and its related adhesion molecules, as well as the molecular matrix of protein hydrolases in the microenvironment of GBM cells and stromal cells.

AIM OF REVIEW

The aim is to enhance our understanding of the molecular mechanisms underlying GBM invasion and to advance research on targeted therapies for inhibiting GBM invasion.

KEY SCIENTIFIC CONCEPTS OF REVIEW

This article describes the protein hydrolases that may affect GBM cell invasion, changes in the cytoskeleton during motility, and the regulatory mechanisms of intracellular signaling pathways in GBM invasion. In addition, we also explored the possibility of targeted therapy against invasion related molecules in GBM.

PKD2: An Important Membrane Protein in Organ Development

PKD2 was first identified as the pathogenic protein for autosomal dominant polycystic kidney disease (ADPKD) and is widely recognized as an ion channel. Subsequent studies have shown that PKD2 is widely expressed in various animal tissues and plays a crucial role in tissue and organ development. Additionally, PKD2 is conserved from single-celled organisms to vertebrates. Here, we provide an overview of recent advances in the function of PKD2 in key model animals, focusing on the establishment of left-right organ asymmetry, renal homeostasis, cardiovascular development, and signal transduction in reproduction and mating. We specifically focus on the roles of PKD2 in development and highlight future prospects for PKD2 research.

Novel Potential Therapeutic Targets in Autosomal Dominant Polycystic Kidney Disease from the Perspective of Cell Polarity and Fibrosis

Autosomal dominant polycystic kidney disease (ADPKD), a congenital genetic disorder, is a notable contributor to the prevalence of chronic kidney disease worldwide. Despite the absence of a complete cure, ongoing research aims for early diagnosis and treatment. Although agents such as tolvaptan and mTOR inhibitors have been utilized, their effectiveness in managing the disease during its initial phase has certain limitations. This review aimed to explore new targets for the early diagnosis and treatment of ADPKD, considering ongoing developments. We particularly focus on cell polarity, which is a key factor that influences the process and pace of cyst formation. In addition, we aimed to identify agents or treatments that can prevent or impede the progression of renal fibrosis, ultimately slowing its trajectory toward end-stage renal disease. Recent advances in slowing ADPKD progression have been examined, and potential therapeutic approaches targeting multiple pathways have been introduced. This comprehensive review discusses innovative strategies to address the challenges of ADPKD and provides valuable insights into potential avenues for its prevention and treatment.

Reduced ossification caused by 3D simulated microgravity exposure is short-term in larval zebrafish

Understanding how skeletal tissues respond to microgravity is ever more important with the increased interest in human space travel. Here, we exposed larval Danio rerio at 3.5 dpf to simulated microgravity (SMG) using a 3D mode of rotation in a ground-based experiment and then studied different cellular, molecular, and morphological bone responses both immediately after exposure and one week later. Our results indicate an overall decrease in ossification in several developing skeletal elements immediately after SMG exposure with the exception of the otoliths, however ossification returns to normal levels seven days after exposure. Coincident with the reduction in overall ossification tnfsf11 (RANKL) expression is highly elevated after 24 h of SMG exposure and also returns to normal levels seven days after exposure. We also show that genes associated with osteoblasts are unaffected immediately after SMG exposure. Thus, the observed reduction in ossification is primarily the result of a high level of bone resorption. This study sheds insight into the nuances of how osteoblasts and osteoclasts in the skeleton of a vertebrate organism respond to an external environmental disturbance, in this case simulated microgravity.

Evaluation of Quantification and Normalization Strategies for Phosphoprotein Phosphatase Affinity Proteomics: Application to Breast Cancer Signaling

Accurate quantification of proteomics data is essential for revealing and understanding biological signaling processes. We have recently developed a chemical proteomic strategy termed phosphatase inhibitor beads and mass spectrometry (PIB-MS) to investigate endogenous phosphoprotein phosphatase (PPP) dephosphorylation signaling. Here, we compare the robustness and reproducibility of status quo quantification methods for optimal performance and ease of implementation. We then apply PIB-MS to an array of breast cancer cell lines to determine differences in PPP signaling between subtypes. Breast cancer, a leading cause of cancer death in women, consists of three main subtypes: estrogen receptor-positive (ER+), human epidermal growth factor receptor two positive (HER2+), and triple-negative (TNBC). Although there are effective treatment strategies for ER+ and HER2+ subtypes, tumors become resistant and progress. Furthermore, TNBC has few targeted therapies. Therefore, there is a need to identify new approaches for treating breast cancers. Using PIB-MS, we distinguished TNBC from non-TNBC based on subtype-specific PPP holoenzyme composition. In addition, we identified an increase in PPP interactions with Hippo pathway proteins in TNBC. These interactions suggest that phosphatases in TNBC play an inhibitory role on the Hippo pathway and correlate with increased expression of YAP/TAZ target genes both in TNBC cell lines and in TNBC patients.

The Hippo signalling pathway and its implications in human health and diseases

As an evolutionarily conserved signalling network, the Hippo pathway plays a crucial role in the regulation of numerous biological processes. Thus, substantial efforts have been made to understand the upstream signals that influence the activity of the Hippo pathway, as well as its physiological functions, such as cell proliferation and differentiation, organ growth, embryogenesis, and tissue regeneration/wound healing. However, dysregulation of the Hippo pathway can cause a variety of diseases, including cancer, eye diseases, cardiac diseases, pulmonary diseases, renal diseases, hepatic diseases, and immune dysfunction. Therefore, therapeutic strategies that target dysregulated Hippo components might be promising approaches for the treatment of a wide spectrum of diseases. Here, we review the key components and upstream signals of the Hippo pathway, as well as the critical physiological functions controlled by the Hippo pathway. Additionally, diseases associated with alterations in the Hippo pathway and potential therapies targeting Hippo components will be discussed.

Dysregulation of the Scribble/YAP/β-catenin axis sustains the fibroinflammatory response in a PKHD1-/- mouse model of congenital hepatic fibrosis

Congenital hepatic fibrosis (CHF), a genetic cholangiopathy characterized by fibropolycystic changes in the biliary tree, is caused by mutations in the PKHD1 gene, leading to defective fibrocystin (FPC), changes in planar cell polarity (PCP) and increased β-catenin-dependent chemokine secretion. In this study, we aimed at understanding the role of Scribble (a protein involved in PCP), Yes-associated protein (YAP), and β-catenin in the regulation of the fibroinflammatory phenotype of FPC-defective cholangiocytes. Immunohistochemistry showed that compared with wild type (WT) mice, in FPC-defective (Pkhd1^del4/del4 ) mice nuclear expression of YAP/TAZ in cystic cholangiocytes, significantly increased and correlated with connective tissue growth factor (CTGF) expression and pericystic fibrosis, while Scribble expression on biliary cyst cells was markedly decreased. Cholangiocytes isolated from WT mice showed intense Scribble immunoreactivity at the membrane, but minimal nuclear expression of YAP, which conversely increased, together with CTGF, after small interfering RNA (siRNA) silencing of Scribble. In FPC-defective cholangiocytes, inhibition of YAP nuclear import reduced β-catenin nuclear expression, and CTGF, integrin β6, CXCL1, and CXCL10 mRNA levels, whereas inhibition of β-catenin signaling did not affect nuclear translocation of YAP. Notably, siRNA silencing of Scribble and YAP in WT cholangiocytes mimics the fibroinflammatory changes of FPC-defective cholangiocytes. Conditional deletion of β-catenin in Pkhd1^del4/del4  mice reduced cyst growth, inflammation and fibrosis, without affecting YAP nuclear expression. In conclusion, the defective anchor of Scribble to the membrane facilitates the nuclear translocation of YAP and β-catenin with gain of a fibroinflammatory phenotype. The Scribble/YAP/β-catenin axis is a critical factor in the sequence of events linking the genetic defect to fibrocystic trait of cholangiocytes in CHF.

Hippo-Yap/Taz signalling in zebrafish regeneration

The extent of tissue regeneration varies widely between species. Mammals have a limited regenerative capacity whilst lower vertebrates such as the zebrafish (Danio rerio), a freshwater teleost, can robustly regenerate a range of tissues, including the spinal cord, heart, and fin. The molecular and cellular basis of this altered response is one of intense investigation. In this review, we summarise the current understanding of the association between zebrafish regeneration and Hippo pathway function, a phosphorylation cascade that regulates cell proliferation, mechanotransduction, stem cell fate, and tumorigenesis, amongst others. We also compare this function to Hippo pathway activity in the regenerative response of other species. We find that the Hippo pathway effectors Yap/Taz facilitate zebrafish regeneration and that this appears to be latent in mammals, suggesting that therapeutically promoting precise and temporal YAP/TAZ signalling in humans may enhance regeneration and hence reduce morbidity.

Novel zebrafish polycystic kidney disease models reveal functions of the Hippo pathway in renal cystogenesis

The Hippo signaling pathway is a kinase cascade that plays an important role in organ size control. As the main effectors of the Hippo pathway, transcription coactivators Yap1/Wwtr1 are regulated by the upstream kinase Stk3. Recent studies in mammals have implicated the Hippo pathway in kidney development and kidney diseases. To further illustrate its roles in vertebrate kidney, we generated a series of zebrafish mutants targeting stk3, yap1 and wwtr1 genes. The stk3^−/− mutant exhibited edema, formation of glomerular cysts and pronephric tubule dilation during the larval stage. Interestingly, disruption of wwtr1, but not yap1, significantly alleviated the renal phenotypes of the stk3^−/− mutant, and overexpression of Wwtr1 with the CMV promoter also induced pronephric phenotypes, similar to those of the stk3^−/− mutant, during larval stage. Notably, adult fish with Wwtr1 overexpression developed phenotypes similar to those of human polycystic kidney disease (PKD). Overall, our analyses revealed roles of Stk3 and Wwtr1 in renal cyst formation. Using a pharmacological approach, we further demonstrated that Stk3-deficient zebrafish could serve as a PKD model for drug development.

Summary: A zebrafish stk3 mutant line and Wwtr1 overexpression line provide evidence for functions of the Hippo signaling pathway in renal cyst formation and represent potential models for polycystic kidney disease.

The cellular pathways and potential therapeutics of Polycystic Kidney Disease

Polycystic Kidney Disease (PKD) refers to a group of disorders, driven by the formation of cysts in renal tubular cells and is currently one of the leading causes of end-stage renal disease. The range of symptoms observed in PKD is due to mutations in cilia-localising genes, resulting in changes in cellular signalling. As such, compounds that are currently in preclinical and clinical trials target some of these signalling pathways that are dysregulated in PKD. In this review, we highlight these pathways including cAMP, EGF and AMPK signalling and drugs that target them and may show promise in lessening the disease burden of PKD patients. At present, tolvaptan is the only approved therapy for ADPKD, however, it carries several adverse side effects whilst comparatively, no pharmacological drug is approved for ARPKD treatment. Aside from this, drugs that have been the subject of multiple clinical trials such as metformin, which targets AMPK signalling and somatostatins, which target cAMP signalling have shown great promise in reducing cyst formation and cellular proliferation. This review also discusses other potential and novel targets that can be used for future interventions, such as β-catenin and TAZ, where research has shown that a reduction in the overexpression of these signalling components results in amelioration of disease phenotype. Thus, it becomes apparent that well-designed preclinical investigations and future clinical trials into these pathways and other potential signalling targets are crucial in bettering disease prognosis for PKD patients and could lead to personalised therapy approaches.

Fibrocystic liver disease: novel concepts and translational perspectives

Fibrocystic liver diseases (FLDs) comprise a heterogeneous group of rare diseases of the biliary tree, having in common an abnormal development of the embryonic ductal plate caused by genetically-determined dysfunctions of proteins expressed in the primary cilia of cholangiocytes (and therefore grouped among the "ciliopathies"). The ductal dysgenesis may affect the biliary system at multiple levels, from the small intrahepatic bile ducts [congenital hepatic fibrosis (CHF)], to the larger intrahepatic bile ducts [Caroli disease (CD), or Caroli syndrome (CS), when CD coexists with CHF], leading to biliary microhamartomas and segmental bile duct dilations. Biliary changes are accompanied by progressive deposition of abundant peribiliary fibrosis. Peribiliary fibrosis and biliary cysts are the fundamental lesions of FLDs and are responsible for the main clinical manifestations, such as portal hypertension, recurrent cholangitis, cholestasis, sepsis and eventually cholangiocarcinoma. Furthermore, FLDs often associate with a spectrum of disorders affecting primarily the kidney. Among them, the autosomal recessive polycystic kidney disease (ARPKD) is the most frequent, and the renal function impairment is central in disease progression. CHF, CD/CS, and ARPKD are caused by a number of mutations in polycystic kidney hepatic disease 1 (PKHD1), a gene that encodes for fibrocystin/polyductin, a protein of unclear function, but supposedly involved in planar cell polarity and other fundamental cell functions. Targeted medical therapy is not available yet and thus the current treatment aims at controlling the complications. Interventional radiology or surgical treatments, including liver transplantation, are used in selected cases.

Scribble sub-cellular localization modulates recruitment of YES1 to regulate YAP1 phosphorylation

The multi-domain scaffolding protein Scribble (Scrib) regulates cell polarity and growth signaling at cell-cell junctions. In epithelial cancers, Scrib mislocalization and overexpression paradoxically transform Scrib from a basolateral tumor suppressor to a cytosolic driver of tumorigenicity. To address the function of Scrib (mis)localization, a Scrib-HaloTag fusion was genome engineered in polarized epithelial cells. Expression of the epithelial to mesenchymal transcription factor Snail displaced Scrib-HaloTag from cell junctions, mirroring the mislocalization observed in cancers. Interestingly, Snail expression promotes Yes-associated protein-1 (YAP1) nuclear localization independent of hippo pathway-regulated YAP-S127 phosphorylation. Furthermore, Scrib HaloPROTAC degradation attenuates YAP1-Y357 phosphorylation. Halo-ligand affinity purification mass spectrometry analysis identified the Src family kinase YES1 as a mislocalized Scrib interaction partner, preferentially recruiting the kinase active and open global conformation (αC helix in). Altogether, mislocalized Scrib enhances YAP1 phosphorylation by scaffolding active YES1.

Expanding the Spectrum of FAT1 Nephropathies by Novel Mutations That Affect Hippo Signaling

Introduction

Disease-causing mutations in the protocadherin FAT1 have been recently described both in patients with a glomerulotubular nephropathy and in patients with a syndromic nephropathy.

Methods

We identified 4 patients with FAT1-associated disease, performed clinical and genetic characterization, and compared our findings to the previously published patients. Patient-derived primary urinary epithelial cells were analyzed by quantitative polymerase chain reaction (qPCR) and immunoblotting to identify possible alterations in Hippo signaling.

Results

Here we expand the spectrum of FAT1-associated disease with the identification of novel FAT1 mutations in 4 patients from 3 families (homozygous truncating variants in 3, compound heterozygous missense variants in 1 patient). All patients show an ophthalmologic phenotype together with heterogeneous renal phenotypes ranging from normal renal function to early-onset end-stage kidney failure. Molecular analysis of primary urine-derived urinary renal epithelial cells revealed alterations in the Hippo signaling cascade with a decreased phosphorylation of both the core kinase MST and the downstream effector YAP. Consistently, we found a transcriptional upregulation of bona fide YAP target genes.

Conclusion

A comprehensive review of the here identified patients and those previously published indicates a highly diverse phenotype in patients with missense mutations but a more uniform and better recognizable phenotype in the patients with truncating mutations. Altered Hippo signaling and de-repressed YAP activity might be novel contributing factors to the pathomechanism in FAT1-associated renal disease.

TAZ/Wnt-β-catenin/c-MYC axis regulates cystogenesis in polycystic kidney disease

Autosomal-dominant polycystic kidney disease (ADPKD) is the most common genetic renal disease, primarily caused by germline mutation of PKD1 or PKD2, leading to end-stage renal disease. There are few cures for ADPKD, although many researchers are trying to find a cure. The Hippo signaling pathway regulates organ growth and cell proliferation. Transcriptional coactivator with PDZ-binding motif (TAZ) is a Hippo signaling effector. In this study, we demonstrated that the PKD1–TAZ–Wnt–β-catenin–c-MYC signaling axis plays a critical role in cystogenesis. Endo IWR1 treatment, which inhibited β-catenin activity via AXIN stabilization, reduced cyst growth in an ADPKD model. Our findings provide a potential therapeutic target against ADPKD and would be important for clinical translation.

Autosomal-dominant polycystic kidney disease (ADPKD) is the most common genetic renal disease, primarily caused by germline mutation of PKD1 or PKD2, leading to end-stage renal disease. The Hippo signaling pathway regulates organ growth and cell proliferation. Herein, we demonstrate the regulatory mechanism of cystogenesis in ADPKD by transcriptional coactivator with PDZ-binding motif (TAZ), a Hippo signaling effector. TAZ was highly expressed around the renal cyst-lining epithelial cells of Pkd1-deficient mice. Loss of Taz in Pkd1-deficient mice reduced cyst formation. In wild type, TAZ interacted with PKD1, which inactivated β-catenin. In contrast, in PKD1-deficient cells, TAZ interacted with AXIN1, thus increasing β-catenin activity. Interaction of TAZ with AXIN1 in PKD1-deficient cells resulted in nuclear accumulation of TAZ together with β-catenin, which up-regulated c-MYC expression. Our findings suggest that the PKD1–TAZ–Wnt–β-catenin–c-MYC signaling axis plays a critical role in cystogenesis and might be a potential therapeutic target against ADPKD.

Hippo signaling-a central player in cystic kidney disease?

Cystic transformation of kidney tissue is a key feature of various disorders including autosomal dominant polycystic kidney disease (ADPKD), autosomal recessive polycystic kidney disease (ARPKD), and disorders of the nephronophthisis spectrum (NPH). While ARPKD and NPH typically affect children and adolescents, pediatric onset of ADPKD is less frequently found. While both ADPKD and ARPKD are characterized by formation of hundreds of cysts accompanied by hyperproliferation of tubular epithelia with massive renal enlargement, NPH patients usually show kidneys of normal or reduced size with cysts limited to the corticomedullary border. Recent results suggest the hippo pathway to be a central regulator at the crossroads of the renal phenotype in both diseases. Hippo signaling regulates organ size and proliferation by keeping the oncogenic transcriptional co-activators Yes associated protein 1 (YAP) and WW domain containing transcription regulator 1 (TAZ) in check. Once this inhibition is released, nuclear YAP/TAZ interacts with TEAD family transcription factors and the consecutive transcriptional activation of TEA domain family members (TEAD) target genes mediates an increase in proliferation. Here, we review the current knowledge on the impact of NPHP and ADPKD mutations on Hippo signaling networks. Furthermore, we provide an outlook towards potential future therapeutic strategies targeting Hippo signaling to alleviate cystic kidney disease.

Autosomal dominant polycystic kidney disease in absence of renal cyst formation illustrates genetic interaction between WT1 and PKD1

PURPOSE

Autosomal dominant polycystic kidney disease (ADPKD), caused by pathogenic variants of either PKD1 or PKD2, is characterised by wide interfamilial and intrafamilial phenotypic variability. This study aimed to determine the molecular basis of marked clinical variability in ADPKD family members and sought to analyse whether alterations of WT1 (Wilms tumour 1), encoding a regulator of gene expression, may have an impact on renal cyst formation.

METHODS

ADPKD family members underwent clinical and molecular evaluation. Functionally, Pkd1 mRNA and protein expression upon Wt1 knockdown was evaluated in mouse embryonic kidneys and mesonephric M15 cells.

RESULTS

By renal gene panel analysis, we identified two pathogenic variants in an individual with maternal history of ADPKD, however, without cystic kidneys but polycystic liver disease: a known PKD1 missense variant (c.8311G>A, p.Glu2771Lys) and a known de novo WT1 splice site variant (c.1432+4C>T). The latter was previously associated with imbalanced +/-KTS isoform ratio of WT1. In ex vivo organ cultures from mouse embryonic kidneys, Wt1 knockdown resulted in decreased Pkd1 expression on mRNA and protein level.

CONCLUSION

While the role of WT1 in glomerulopathies has been well established, this report by illustrating genetic interaction with PKD1 proposes WT1 as potential modifier in ADPKD.

The Role of Wnt Signalling in Chronic Kidney Disease (CKD)

Chronic kidney disease (CKD) encompasses a group of diverse diseases that are associated with accumulating kidney damage and a decline in glomerular filtration rate (GFR). These conditions can be of an acquired or genetic nature and, in many cases, interactions between genetics and the environment also play a role in disease manifestation and severity. In this review, we focus on genetically inherited chronic kidney diseases and dissect the links between canonical and non-canonical Wnt signalling, and this umbrella of conditions that result in kidney damage. Most of the current evidence on the role of Wnt signalling in CKD is gathered from studies in polycystic kidney disease (PKD) and nephronophthisis (NPHP) and reveals the involvement of β-catenin. Nevertheless, recent findings have also linked planar cell polarity (PCP) signalling to CKD, with further studies being required to fully understand the links and molecular mechanisms.

Molecular pathways involved in injury-repair and ADPKD progression

The major hallmark of Autosomal Dominant Polycystic Kidney Disease (ADPKD) is the formation of many fluid-filled cysts in the kidneys, which ultimately impairs the normal renal structure and function, leading to end-stage renal disease (ESRD). A large body of evidence suggests that injury-repair mechanisms are part of ADPKD progression. Once cysts have been formed, proliferation and fluid secretion contribute to the cyst size increase, which eventually causes stress on the surrounding tissue resulting in local injury and fibrosis. In addition, renal injury can cause or accelerate cyst formation. In this review, we will describe the various mechanisms activated during renal injury and tissue repair and show how they largely overlap with the molecular mechanisms activated during PKD progression. In particular, we will discuss molecular mechanisms such as proliferation, inflammation, cell differentiation, cytokines and growth factors secretion, which are activated following the renal injury to allow the remodelling of the tissue and a proper organ repair. We will also underline how, in a context of PKD-related gene mutations, aberrant or chronic activation of these developmental pathways and repair/remodelling mechanisms results in exacerbation of the disease.

Polycystin-1 Regulates Actomyosin Contraction and the Cellular Response to Extracellular Stiffness

Polycystin-1 (PC-1) and 2 (PC-2) are the products of the PKD1 and PKD2 genes, which are mutated in Autosomal Dominant Polycystic Kidney Disease (ADPKD). They form a receptor/channel complex that has been suggested to function as a mechanosensor, possibly activated by ciliary bending in the renal tubule, and resulting in calcium influx. This model has recently been challenged, leaving the question as to which mechanical stimuli activate the polycystins still open. Here, we used a SILAC/Mass-Spec approach to identify intracellular binding partners of tagged-endogenous PC-1 whereby we detected a class of interactors mediating regulation of cellular actomyosin contraction. Accordingly, using gain and loss-of-function cellular systems we found that PC-1 negatively regulates cellular contraction and YAP activation in response to extracellular stiffness. Thus, PC-1 enables cells to sense the rigidity of the extracellular milieu and to respond appropriately. Of note, in an orthologous murine model of PKD we found evidence of increased actomyosin contraction, leading to enhanced YAP nuclear translocation and transcriptional activity. Finally, we show that inhibition of ROCK-dependent actomyosin contraction by Fasudil reversed YAP activation and significantly improved disease progression, in line with recent studies. Our data suggest a possible direct role of PC-1 as a mechanosensor of extracellular stiffness.

The Hippo Pathway Is Essential for Maintenance of Apicobasal Polarity in the Growing Intestine of Caenorhabditis elegans

Although multiple determinants for establishing polarity in membranes of epithelial cells have been identified, the mechanism for maintaining apicobasal polarity is not fully understood. Here, we show that the conserved Hippo kinase pathway plays a role in the maintenance of apicobasal polarity in the developing intestine of Caenorhabditis elegans We screened suppressors of the mutation in wts-1-the gene that encodes the LATS kinase homolog, deficiency of which leads to disturbance of the apicobasal polarity of the intestinal cells and to eventual death of the organism. We identified several alleles of yap-1 and egl-44 that suppress the effects of this mutation. yap-1 encodes a homolog of YAP/Yki, and egl-44 encodes a homolog of TEAD/Sd. WTS-1 bound directly to YAP-1 and inhibited its nuclear accumulation in intestinal cells. We also found that NFM-1, which is a homolog of NF2/Merlin, functioned in the same genetic pathway as WTS-1 to regulate YAP-1 to maintain cellular polarity. Transcriptome analysis identified several target candidates of the YAP-1-EGL-44 complex including TAT-2, which encodes a putative P-type ATPase. In summary, we have delineated the conserved Hippo pathway in C. elegans consisting of NFM-1-WTS-1-YAP-1-EGL-44 and proved that the proper regulation of YAP-1 by upstream NFM-1 and WTS-1 is essential for maintenance of apicobasal membrane identities of the growing intestine.

Identification of Key Genes and Candidated Pathways in Human Autosomal Dominant Polycystic Kidney Disease by Bioinformatics Analysis

Background/Aims: Autosomal dominant polycystic kidney disease (ADPKD) is the most common genetic form of kidney disease. High-throughput microarray analysis has been applied for elucidating key genes and pathways associated with ADPKD. Most genetic profiling data from ADPKD patients have been uploaded to public databases but not thoroughly analyzed. This study integrated 2 human microarray profile datasets to elucidate the potential pathways and protein-protein interactions (PPIs) involved in ADPKD via bioinformatics analysis in order to identify possible therapeutic targets. Methods: The kidney tissue microarray data of ADPKD patients and normal individuals were searched and obtained from NCBI Gene Expression Omnibus. Differentially expressed genes (DEGs) were identified, and enriched pathways and central node genes were elucidated using related websites and software according to bioinformatics analysis protocols. Seven DEGs were validated between polycystic kidney disease and control kidney samples by quantitative real-time polymerase chain reaction. Results: Two original human microarray datasets, GSE7869 and GSE35831, were integrated and thoroughly analyzed. In total, 6,422 and 1,152 DEGs were extracted from GSE7869 and GSE35831, respectively, and of these, 561 DEGs were consistent between the databases (291 upregulated genes and 270 downregulated genes). From 421 nodes, 34 central node genes were obtained from a PPI network complex of DEGs. Two significant modules were selected from the PPI network complex by using Cytotype MCODE. Most of the identified genes are involved in protein binding, extracellular region or space, platelet degranulation, mitochondrion, and metabolic pathways. Conclusions: The DEGs and related enriched pathways in ADPKD identified through this integrated bioinformatics analysis provide insights into the molecular mechanisms of ADPKD and potential therapeutic strategies. Specifically, abnormal decorin expression in different stages of ADPKD may represent a new therapeutic target in ADPKD, and regulation of metabolism and mitochondrial function in ADPKD may become a focus of future research.