👤 Mansi Goyal

Intracerebroventricular (ICV) streptozotocin (STZ) deveops Alzheimer's disease (AD)-like conditions in rodents, which are characterized by insulin resistance, tau pathology, and neurodegeneration. Hentriacontane, a natural compound found in various sources, including beeswax, possesses anti-inflammatory and antioxidant properties. In the present investigation, we performed in silico molecular docking, molecular dynamics, MMGBSA, PCA, and FEL analysis of hentriacontane and rivastigmine with acetylcholinesterase (AchE). Further, we assessed the in vivo neuroprotective effects of hentriacontane in an ICV-STZ-induced AD-like condition in rats. STZ (3 mg/kg/ICV) was injected into male Sprague-Dawley rats. Cognitive functions were evaluated by Barnes-Maze (BM), novel object recognition test (NORT), and passive avoidance test (PAT). Hentriacontane (3 and 5 mg/kg) and rivastigmine (1 mg/kg) were given intraperitoneally for 14 days. Brain-derived neurotrophic factor (BDNF), AchE, oxidative stress parameters including GSH, MDA, SOD, and CAT, and proinflammatory cytokines including IL-6, TNF-α, IL-1β, and NF-ҡB were measured via ELISA. Further, we have also estimated the BACE1 and NO levels. Histopathological evaluation was conducted using hematoxylin and eosin staining. In silico molecular docking, dynamics, and post-dynamics data revealed promising binding affinities of hentriacontane for AchE. Further, hentriacontane attenuated ICV-STZ-induced cognitive deficit in BM, NORT, and PAT. Additionally, altered oxidative stress, proinflammatory, and cell signalling parameters were restored. Histopathology revealed that the hentriacontane-treated group showed significant restoration of the small pyramidal cells in the CA1 and CA2 regions of the brain. Hentriacontane demonstrated neuroprotective effects by modulation of AchE, leading to improved cognitive functions as evidenced by in silico and in vivo investigations. Show less

Genetic variation and lived experiences shape how our hearts respond to chronic stress and development of heart failure, manifested as compromised pumping function and abnormal hemodynamics. The hallmark of heart failure etiology is excessive stress signals followed by maladaptive structural, electrical, and functional changes to the heart muscle, also known as cardiac remodeling. The specific genetic mechanisms which underly such phenomenon, however, are still unclear, due in part to difficulties in accounting for environmental effects in human population studies. To overcome this challenge, we used the Collaborative Cross (CC) mouse population to investigate heritable susceptibility to cardiovascular stress by chronic β-adrenergic receptor stimulation with the β-agonist isoproterenol, which targets the common signaling gateway to heart failure, regardless of the particular upstream stressor. Across 8 founder and 63 CC lines, we measured non-failing and failing heart characteristics represented by cardiac structure and function, organ weights, and cell morphology. Genome-wide QTL mapping detected 49 genome-wide significant loci, collapsing to 20 unique intervals (nine significant for multiple traits and eleven trait-specific), averaging 12.83 Mb in size. To identify high-confidence candidate genes from these loci, we augmented our trait mapping with coding variants drawn from sequencing data, tractability in our in vitro rat cardiomyocyte model, and previously reported protein functions and mouse or human phenotypes. This approach recovered both known regulators, such as Hey2, and new candidates. Functional tests in in vitro models highlight three candidate genes that modulate hypertrophic growth: Abcb10, Mrps5 and Lmod3. Abcb10 knockdown increased cell size at baseline and further with isoproterenol, consistent with loss of a mitochondrial stress-buffering role. Mrps5 knockdown blunted stress-induced hypertrophy, possibly related to its previously known involvement in oxidative stress regulation. Lmod3 knockdown also attenuated hypertrophy, potentially via actin-assembly control under adrenergic stress. Together, these results reveal heritable pathways of β-adrenergic remodeling in mice and provide an interpretable, translational, and stepwise framework to prioritize candidate genes within broad loci for mechanistic studies of heart failure. Show less

Alzheimer's disease (AD) is a neurodegenerative disorder marked by a decline in cognitive function and memory loss, primarily resulting from cholinergic dysfunction, the accumulation of amyloid plaques, the formation of tau tangles, and the progressive degeneration of neurons. While existing treatments offer limited symptomatic relief, they do not effectively halt or reverse the underlying progression of the disease, presenting a major global challenge in Alzheimer's research. Developing therapeutic strategies for AD remains complex, largely due to the inability of current medications to significantly slow neurodegeneration. Traditional drug discovery processes are often lengthy, costly, and inefficient, further complicating the search for effective treatments. To overcome these obstacles, researchers have turned to a combination of computational approaches alongside conventional drug design techniques. These integrated methodologies help accelerate the discovery process by significantly reducing both time and costs. This review delves into the underlying physiological and pathological mechanisms of Alzheimer's disease, while identifying potential drug targets such as acetylcholinesterase, butyrylcholinesterase, β-Secretase (BACE-1), A2A adenosine receptor, Dickkopf-1 protein, glycogen synthase kinase-3β, indoleamine 2,3-dioxygenase, monoamine oxidase-B, NMDA receptor, Wnt inhibitory factor, cyclindependent kinase-5, glutaminyl cyclase, and cathepsin-B. Furthermore, the review examines various computer-aided drug design (CADD) methodologies, including structure-based and ligandbased approaches, virtual screening, pharmacophore modeling, molecular modelling, and simulation techniques. These computational strategies are playing an increasingly important role in Alzheimer's research, particularly in drug discovery. By investigating promising drug candidates and lead molecules that target key proteins involved in Alzheimer's pathogenesis, the review highlights their binding modes with these targets and assesses the chemical properties essential for the development of effective clinical candidates. The aim is to provide researchers with critical insights and tools to design novel compounds with the necessary chemical and physical characteristics required for the successful treatment of Alzheimer's disease. Show less

Thiazine, a six-membered heterocycle containing nitrogen and sulfur atoms, is of paramount importance due to its diverse biological functions and broad therapeutic effects. The pharmacological attributes of 1,3-thiazine span a wide range of activities, including antileukemic, antimycobacterial, anti-inflammatory, sedative, hypnotic, anti-influenza, antituberculosis, melanogenesis inhibition, BACE1 inhibition (with anti-Alzheimer's potential), growth promotion, neuroprotective, and anticonvulsant properties. Consequently, novel synthetic methodologies and the design of new 1,3-thiazine derivatives are significantly influenced by recent research findings. This comprehensive review explores both Show less

Central nervous system (CNS) tumors often harbor alterations in genes regulating key cellular pathways, including fibroblast growth factor receptor (FGFR) genes. Here, we report the efficacy and safety of treatment with pemigatinib, an oral, potent, selective FGFR1-3 inhibitor, in patients with advanced FGFR-altered CNS tumors. FIGHT-207 was a single-arm, open-label, phase 2 study of pemigatinib in patients with advanced solid tumors harboring FGFR fusions/rearrangements or other mutations. Patients received pemigatinib 13.5 mg once daily until disease progression or unacceptable toxicity. Endpoints included tumor response and safety. Of the 13 patients with CNS tumors in FIGHT-207, 10 had glioblastoma. Fibroblast growth factor receptor alterations were FGFR3-TACC3 fusions (n = 9), FGFR1 K656E mutations (n = 2), FGFR1 N546K mutation (n = 1), and FGFR1-MITF fusion (n = 1). Three patients (23%) displayed objective responses (1 complete, 2 partial). Safety was consistent with the overall FIGHT-207 population. Pemigatinib had antitumor activity and a manageable safety profile in patients with CNS tumors. Show less

Futibatinib is the only covalent inhibitor of FGFR1-4 to gain regulatory approval in oncology. In this article, we present genomic analyses of tissue biopsies and circulating tumor DNA (ctDNA) from patients with 1 of nearly 20 tumor types treated with futibatinib in the phase I/II FOENIX study. Eligible patients included those with ctDNA samples collected per protocol at baseline and/or progression on futibatinib in the phase Ib portion of the study for FGF/FGFR-altered advanced solid tumors or the phase II portion of the study for FGFR2 fusion/rearrangement-positive cholangiocarcinoma. Assessments included analytical concordance between tumor and ctDNA analyses for detection of FGFR alterations, association of ctDNA-detected co-occurring genomic alterations with response to futibatinib, and determination of patterns of acquired resistance following progression on futibatinib. Among 300 patients treated with futibatinib, 226 were eligible for this analysis, including 139 (62%) with cholangiocarcinoma. Among patients with known FGFR2 fusions/rearrangements, FGFR1 fusions, FGFR3 fusions, or FGFR2 amplifications per tissue analysis, detection rates in ctDNA for these aberrations were 84%, 0%, 11%, and 59%, respectively. Objective response rates on futibatinib were not significantly different between patients with TP53-altered versus -unaltered solid tumors; progression-free survival was reduced in patients with CDKN2B-altered versus -unaltered cholangiocarcinoma (median 4.8 versus 11.0 months; P = 0.03). Acquired resistance to futibatinib was frequently polyclonal and driven by an array of mutations within the relevant FGFR kinase domain, predominantly V565L, V565F, and N550K variants. In this largest and most systematic analysis of acquired resistance to an FGFR inhibitor from prospective clinical trials, emergence of secondary FGFR2 kinase domain mutations was observed in most patients receiving clinical benefit to futibatinib. ctDNA analysis shows clinically relevant potential as a noninvasive method for assessing genomic profiles, identifying patients who may benefit from FGFR inhibitor treatment, and exploring acquired resistance mechanisms. Show less

Hypertrophic cardiomyopathy (HCM), associated with left ventricular hypertrophy, can lead to significant morbidity. Given the hereditary association, identifying population-specific genetic markers and gender disparities could enable better screening and management strategies. The study aimed to observe the genetic patterns of HCM and investigate its gender associations among the Indian population. A prospective analysis was performed based on the medical records of patients with HCM. Genetic testing was conducted among those with a family history of HCM or sudden cardiac death. Genetic testing results, echocardiography, and clinical outcomes were documented. The prevalence of HCM types and genetic abnormalities were estimated in the study population and were compared between the two genders. The study included 103 patients with a mean age of 56.3 ± 13.9 years. Genetic analysis was conducted in 48/103 individuals based on the hereditary linkage. Only 50% of the 48 individuals had known genes associated with HCM. About 48% had apical or midapical HCM, and 31.1% had reverse curvature HCM. About 38% of apical and 60% of neutral or reverse curvature were associated with genetic abnormalities. The more commonly associated genes were MYBPC3 and MYH7. The current study also identified genetic variants in several emerging genes in Indian HCM patients. Our study findings indicate that the prevalence of different types of HCM is different in the Indian population. With only 50% of the hereditary HCM linked to known genes, the study calls for further screening of genes associated with HCM in the Indian population. Show less

Hypertrophic cardiomyopathy (HCM) is an autosomal dominant genetic disorder characterized by left ventricular hypertrophy and variable clinical manifestations, including asymptomatic states and sudden cardiac death (SCD). Data on its phenotype and genotype in the Indian population remain limited. We studied 113 patients diagnosed with HCM. All underwent clinical assessment, 24-h Holter monitoring, echocardiography, and cardiac MRI. Genetic testing was performed in 80 patients. Clinical and imaging features were compared between genotype-positive and genotype-negative groups. The mean age was 47 ± 10.8 years, with 82.6 % being males. Dyspnoea and chest pain were the most frequent symptoms. Obstructive HCM was seen in 70 (61.9 %) patients. Cardiac MRI showed late gadolinium enhancement >15 % in 13 (23.2 %) and apical aneurysms in 2 (3.5 %). Genetic mutations were detected in 40 (50 %) patients, with MYBPC3 (33 %) and MYH7 (26.8 %) being most common. Genotype-positive individuals more frequently had chest pain, a family history of SCD, and more severe hypertrophy. In this Indian HCM cohort, the condition predominantly affected males. Genotype-positive patients exhibited more severe hypertrophy and adverse clinical profiles, underscoring the importance of genetic screening in risk stratification. Show less

Atherosclerosis is a chronic condition characterized by impaired lipid homeostasis and chronic inflammatory pathology in large and mid-sized arteries. Myocardial infarction is caused by coronary artery thrombosis in a ruptured or unstable atherosclerotic plaque. Despite the emphasis on known triggering factors, such as hypertension and dyslipidemia, adverse events following MI, such as recurrence and mortality, are still high. Therefore, it is imperative to assess potential determinants of plaque instability. We evaluated markers of inflammation, extracellular matrix (ECM) remodeling, thrombosis, and lipids in first-time and recurrent MI (RMI). Two hundred patients diagnosed with MI within the first 24 h of the event were included in the study and categorized as first-time or recurrent MI. Serum levels of NF-κB, hs-CRP, TNF-α, IFN γ, IL-6, VCAM-1,MMP-9, stromelysin, TIMP-1, MCP-1, PAPP-A, vWF, D-dimer, PLA2, PON-1, Apo-B, Apo-A1, ox-LDL, and anti-oxidized LDL antibodies were analyzed by ELISA. We performed a multivariate logistic regression analysis for risk stratification. The mean age of first-time MI patients was 52.4 ± 25 years and that of recurrent MI patients was 55.9 ± 24.6 years. RMI patients showed significant ( Non-lipid factors provide substantial insights into plaque instability. Multiple markers of inflammation, thrombosis, extracellular matrix remodeling, and paroxonase-1 are reliable indicators of recurrent myocardial infarction. Show less

BRAF and MEK inhibitors are standard treatments in histiocytic disorders, such as Erdheim-Chester disease (ECD). Some patients lack MAPK-pathway alterations, making these treatments less effective. We describe three patients with histiocytic disorders who have novel non-MAPK pathway alterations. These alterations were studied through genomic and in silico analyses when applicable, then treated with off-label medications rationally selected on the basis of genomic alterations. Patient 1 had rapidly progressive ECD involving the CNS. A CSF1R in-frame deletion (p.S560_P566del) was identified, and in silico modeling predicted a gain-of-function mutation. This alteration was targeted with pexidartinib, which led to a clinical complete response (CR) within 2 months, and a partial response (PR) on imaging after 3 months. After 15 months, the disease became resistant to pexidartinib and transformed to histiocytic sarcoma. Patient 2 has skin-only involvement of a xanthogranuloma disorder. A KIF5B-FGFR1 fusion was identified on RNA sequencing and targeted with pemigatinib. At 24 months of follow-up, she remains in a clinical PR. Patient 3 has ECD involving the bone marrow, gastrointestinal tract, and subcutaneous tissues. A MEF2C-FLT3 fusion was identified and targeted with sorafenib. He achieved a clinical CR and radiographic PR within 3 months, which has continued for 30 months. We report three patients with histiocytic disorders harboring novel alterations who had sustained responses to off-label kinase inhibitors specific to their histiocytic disorder. Pathogenic variants outside of the MAPK pathway, including variants of unknown significant, may be targeted with readily available small molecules. Show less

This multicenter phase II basket trial investigated the efficacy, safety, and pharmacokinetics of Debio 1347, an investigational, oral, highly selective, ATP-competitive, small molecule inhibitor of FGFR1-3, in patients with solid tumors harboring a functional FGFR1-3 fusion. Eligible adults had a previously treated locally advanced (unresectable) or metastatic biliary tract (cohort 1), urothelial (cohort 2), or another histologic cancer type (cohort 3). Debio 1347 was administered at 80 mg once daily, continuously, in 28-day cycles. The primary endpoint was the objective response rate. Secondary endpoints included duration of response, progression-free survival, overall survival, pharmacokinetics, and incidence of adverse events. Between March 22, 2019, and January 8, 2020, 63 patients were enrolled and treated, 30 in cohort 1, 4 in cohort 2, and 29 in cohort 3. An unplanned preliminary statistical review showed that the efficacy of Debio 1347 was lower than predicted, and the trial was terminated. In total, 3 of 58 evaluable patients had partial responses, representing an objective response rate of 5%, with a further 26 (45%) having stable disease (≥6 weeks duration). Grade ≥3 treatment-related adverse events occurred in 22 (35%) of 63 patients, with the most common being hyperphosphatemia (13%) and stomatitis (5%). Two patients (3%) discontinued treatment due to adverse events. Debio 1347 had manageable toxicity; however, the efficacy in patients with tumors harboring FGFR fusions did not support further clinical evaluation in this setting. Our transcriptomic-based analysis characterized in detail the incidence and nature of FGFR fusions across solid tumors. See related commentary by Hage Chehade et al., p. 4549. Show less

Fibroblast growth factor receptor (FGFR) alterations drive oncogenesis in multiple tumor types. Here we studied pemigatinib, a selective, potent, oral FGFR1-FGFR3 inhibitor, in the phase 2 FIGHT-207 basket study of FGFR-altered advanced solid tumors. Primary end points were objective response rate (ORR) in cohorts A (fusions/rearrangements, n = 49) and B (activating non-kinase domain mutations, n = 32). Secondary end points were progression-free survival, duration of response and overall survival in cohorts A and B, and safety. Exploratory end points included ORR of cohort C (kinase domain mutations, potentially pathogenic variants of unknown significance, n = 26) and analysis of co-alterations associated with resistance and response. ORRs for cohorts A, B and C were 26.5% (13/49), 9.4% (3/32) and 3.8% (1/26), respectively. Tumors with no approved FGFR inhibitors or those with alterations not previously confirmed to be sensitive to FGFR inhibition had objective responses. In cohorts A and B, the median progression-free survival was 4.5 and 3.7 months, median duration of response was 7.8 and 6.9 months and median overall survival was 17.5 and 11.4 months, respectively. Safety was consistent with previous reports. The most common any-grade treatment-emergent adverse events were hyperphosphatemia (84%) and stomatitis (53%). TP53 co-mutations were associated with lack of response and BAP1 alterations with higher response rates. FGFR1-FGFR3 gatekeeper and molecular brake mutations led to acquired resistance. New therapeutic areas for FGFR inhibition and drug failure mechanisms were identified across tumor types. ClinicalTrials.gov identifier: NCT03822117 . Show less

Futibatinib, a covalently-binding inhibitor of fibroblast growth factor receptor (FGFR)1-4 gained approval for the treatment of refractory, advanced intrahepatic cholangiocarcinoma (iCCA) harboring an FGFR2 fusion/other rearrangement. An integrated analysis was performed to evaluate safety and provide guidance on the management of futibatinib-associated adverse events (AEs) in patients with unresectable/metastatic tumors, including iCCA. Data from three global phase I or II studies of futibatinib (NCT02052778; JapicCTI-142552) were pooled. AEs were graded per NCI CTCAE v4.03, where applicable. Safety was analyzed for patients receiving any futibatinib starting dose (overall population) and in those receiving the approved starting dose of 20 mg once every day. In total, 469 patients with one of 33 known tumor types were analyzed, including 318 patients who received futibatinib 20 mg every day. AEs of clinical interest (AECI; any grade/grade ≥3) in the overall population included hyperphosphatemia (82%/19%), nail disorders (27%/1%), hepatic AEs (27%/11%), stomatitis (19%/3%), palmar-plantar erythrodysesthesia syndrome (PPES; 13%/3%), rash (9%/0%), retinal disorders (8%/0%), and cataract (4%/1%). Median time to onset of grade ≥3 AECIs ranged from 9 days (hyperphosphatemia) to 125 days (cataract). Grade ≥3 hyperphosphatemia, hepatic AEs, PPES, and nail disorders resolved to grade ≤2 within a median of 7, 7, 8, and 28 days, respectively. Discontinuations due to treatment-related AEs were rare (2%), and no treatment-related deaths occurred. AE management included phosphate-lowering medication and dose adjustments. Futibatinib showed a consistent and manageable safety profile across patients with various tumor types. AECIs were mostly reversible with appropriate clinical management. Show less

Amyloid-β (Aβ) aggregation and β-amyloid precursor protein cleaving enzyme 1 (BACE1) are the potential therapeutic drug targets for Alzheimer's disease (AD). A recent study highlighted that tacrine-benzofuran hybrid C1 displayed anti-aggregation activity against Aβ Show less

Oncogenic activation of fibroblast growth factor receptor 2 (FGFR2) drives multiple cancers and represents a broad therapeutic opportunity, yet selective targeting of FGFR2 has not been achieved. Although the clinical efficacy of pan-FGFR inhibitors (pan-FGFRi) validates FGFR2 driver status in FGFR2 fusion-positive intrahepatic cholangiocarcinoma, their benefit is limited by incomplete target coverage due to FGFR1- and FGFR4-mediated toxicities (hyperphosphatemia and diarrhea, respectively) and the emergence of FGFR2 resistance mutations. RLY-4008 is a highly selective, irreversible FGFR2 inhibitor designed to overcome these limitations. In vitro, RLY-4008 demonstrates >250- and >5,000-fold selectivity over FGFR1 and FGFR4, respectively, and targets primary alterations and resistance mutations. In vivo, RLY-4008 induces regression in multiple xenograft models-including models with FGFR2 resistance mutations that drive clinical progression on current pan-FGFRi-while sparing FGFR1 and FGFR4. In early clinical testing, RLY-4008 induced responses without clinically significant off-isoform FGFR toxicities, confirming the broad therapeutic potential of selective FGFR2 targeting. Patients with FGFR2-driven cancers derive limited benefit from pan-FGFRi due to multiple FGFR1-4-mediated toxicities and acquired FGFR2 resistance mutations. RLY-4008 is a highly selective FGFR2 inhibitor that targets primary alterations and resistance mutations and induces tumor regression while sparing other FGFRs, suggesting it may have broad therapeutic potential. See related commentary by Tripathi et al., p. 1964. This article is featured in Selected Articles from This Issue, p. 1949. Show less

Parkinson's disease (PD) is a genetically heterogeneous neurodegenerative disease with poorly defined environmental influences. Genomic studies of PD patients have identified disease-relevant monogenic genes, rare variants of significance, and polygenic risk-associated variants. In this study, whole genome sequencing data from 90 young onset Parkinson's disease (YOPD) individuals are analyzed for both monogenic and polygenic risk. The genetic variant analysis identifies pathogenic/likely pathogenic variants in eight of the 90 individuals (8.8%). It includes large homozygous coding exon deletions in PRKN and SNV/InDels in VPS13C, PLA2G6, PINK1, SYNJ1, and GCH1. Eleven rare heterozygous GBA coding variants are also identified in 13 (14.4%) individuals. In 34 (56.6%) individuals, one or more variants of uncertain significance (VUS) in PD/PD-relevant genes are observed. Though YOPD patients with a prioritized pathogenic variant show a low polygenic risk score (PRS), patients with prioritized VUS or no significant rare variants show an increased PRS odds ratio for PD. This study suggests that both significant rare variants and polygenic risk from common variants together may contribute to the genesis of PD. Further validation using a larger cohort of patients will confirm the interplay between monogenic and polygenic variants and their use in routine genetic PD diagnosis and risk assessment. Show less

Hypertriglyceridemia has emerged as a critical coronary artery disease (CAD) risk factor. Rare loss-of-function (LoF) variants in apolipoprotein C-III have been reported to reduce triglycerides (TG) and are cardioprotective in American Indians and Europeans. However, there is a lack of data in other Europeans and non-Europeans. Also, whether genetically increased plasma TG due to ApoC-III is causally associated with increased CAD risk is still unclear and inconsistent. The objectives of this study were to verify the cardioprotective role of earlier reported six LoF variants of APOC3 in South Asians and other multi-ethnic cohorts and to evaluate the causal association of TG raising common variants for increasing CAD risk. We performed gene-centric and Mendelian randomization analyses and evaluated the role of genetic variation encompassing APOC3 for affecting circulating TG and the risk for developing CAD. One rare LoF variant (rs138326449) with a 37% reduction in TG was associated with lowered risk for CAD in Europeans (p = 0.007), but we could not confirm this association in Asian Indians (p = 0.641). Our data could not validate the cardioprotective role of other five LoF variants analysed. A common variant rs5128 in the APOC3 was strongly associated with elevated TG levels showing a p-value 2.8 × 10 Our results highlight the challenges of inclusion of rare variant information in clinical risk assessment and the generalizability of implementation of ApoC-III inhibition for treating atherosclerotic disease. More studies would be needed to confirm whether genetically raised TG and ApoC-III concentrations would increase CAD risk. Show less

We tested the hypothesis that endothelial capillary tube formation in 3D cultures in basement membrane extract (BME) is secondary to the altered DNA promoter methylation and mRNA expression in human brain micro endothelial cells (HBMECs). We conducted a whole-genome transcriptomic and methylation microarray and CRISPR/Cas9-mediated gene knockdown to test our hypothesis. The data demonstrated that with angiogenic transformation 1318 and 1490 genes were significantly ( Show less

A novel series of 17beta-hydroxysteroid dehydrogenase type 3 (17beta-HSD3) inhibitors has been identified. These inhibitors, based on a dibenzazocine core, exhibited picomolar to low nanomolar inhibition of 17beta-HSD3 in cell-free enzymatic as well as in cell-based transcriptional reporter assays. Show less

Membrane-associated guanylate kinase (Maguk) proteins are scaffold proteins that contain PSD-95-Discs Large-zona occludens-1 (PDZ), Src homology 3, and guanylate kinase domains. A subset of Maguk proteins, such as mLin-2 and protein associated with Lin-7 (Pals)1, also contain two L27 domains: an L27C domain that binds mLin-7 and an L27N domain of unknown function. Here, we demonstrate that the L27N domain targets Pals1 to tight junctions by binding to a PDZ domain protein, Pals1-associated tight junction (PATJ) protein, via a unique Maguk recruitment domain. PATJ is a homologue of Drosophila Discs Lost, a protein that is crucial for epithelial polarity and that exists in a complex with the apical polarity determinant, Crumbs. PATJ and a human Crumbs homologue, CRB1, colocalize with Pals1 to tight junctions, and CRB1 interacts with PATJ albeit indirectly via binding the Pals1 PDZ domain. In agreement, we find that a Drosophila homologue of Pals1 participates in identical interactions with Drosophila Crumbs and Discs Lost. This Drosophila Pals1 homologue has been demonstrated recently to represent Stardust, a crucial polarity gene in Drosophila. Thus, our data identifies a new multiprotein complex that appears to be evolutionarily conserved and likely plays an important role in protein targeting and cell polarity. Show less