👤 Coleen A McNamara

TrkB, a receptor tyrosine kinase encoded by gene NTRK2, is essential for diverse biological processes in both the developing and mature mammalian nervous systems. Whole exome sequencing of children with developmental epileptic encephalopathy revealed an intriguing syndrome caused by a rare de novo recurrent variant of TrkB, namely Y434C. Investigating the biochemical properties of the Y434C mutant protein is an important initial step toward understanding how this mutation causes this devastating disease. This led us to establish and characterize multiple cell lines stably expressing mouse WT or Y434C TrkB. In comparison to WT, Y434C mutant cell lines expressed low to undetectable levels of mature form (145 kDa) of TrkB protein and varying levels of mutant forms migrating at sizes ranging from 40 to 110 kDa. Y434C mutant cell lines exhibited striking impairments of brain-derived neurotrophic factor-mediated activation of TrkB signaling. Reducing agents reduced high molecular weight forms of Y434C protein multimers detected in protein gel electrophoresis, consistent with disulfide bond formation between the Y434C mutant proteins. We propose that conversion of tyrosine to cysteine at amino acid 434 results in a novel intermolecular disulfide bond between Y434C mutant proteins, thereby modifying their structure and enhancing their proteolytic digestion. The ensuing reductions of the mature form of TrkB likely underlie impaired TrkB signaling. The proteolytic fragments of TrkB may themselves have deleterious consequences, which contribute to the phenotypic manifestations of the Y434C TrkB mutation. Show less

Atherosclerosis underlies most coronary artery disease (CAD). It involves a significant autoimmune component against apolipoprotein B (APOB). In this study, we used short activation-induced marker (AIM) assays to characterize APOB-reactive CD4 Show less

The hiPSC-derived cardiomyocytes (hiPSC-CMs) and hCOs were generated from human subjects to define the molecular, cellular, and functional changes caused by the Confocal and electron microscopic analyses of hCOs generated from noncarriers (NC) and carriers of the Conceptually, we showed the feasibility of assessing the functional and molecular mechanisms of HCM using highly translatable hCOs through pragmatic experiments that led to determining the Show less

Hypertrophic cardiomyopathy (HCM) is an inherited cardiovascular disorder primarily caused by mutations in the β-myosin heavy-chain gene. The proximal subfragment 2 region (S2), 126 amino acids of myosin, binds with the C0-C2 region of cardiac myosin-binding protein-C to regulate cardiac muscle contractility in a manner dependent on PKA-mediated phosphorylation. However, it is unknown if HCM-associated mutations within S2 dysregulate actomyosin dynamics by disrupting its interaction with C0-C2, ultimately leading to HCM. Herein, we study three S2 mutations known to cause HCM: R870H, E924K, and E930Δ. First, experiments using recombinant proteins, solid-phase binding, and isothermal titrating calorimetry assays independently revealed that mutant S2 proteins displayed significantly reduced binding with C0-C2. In addition, CD revealed greater instability of the coiled-coil structure in mutant S2 proteins compared with S2 Show less

Phosphorylation of cardiac myosin binding protein-C (cMyBP-C) regulates cardiac contraction through modulation of actomyosin interactions mediated by the protein's amino terminal (N')-region (C0-C2 domains, 358 amino acids). On the other hand, dephosphorylation of cMyBP-C during myocardial injury results in cleavage of the 271 amino acid C0-C1f region and subsequent contractile dysfunction. Yet, our current understanding of amino terminus region of cMyBP-C in the context of regulating thin and thick filament interactions is limited. A novel cardiac-specific transgenic mouse model expressing cMyBP-C, but lacking its C0-C1f region (cMyBP-C Show less

Hypertrophic cardiomyopathy (HCM) is a genetic disease of the heart and the most common cause of sudden cardiac death in the young. HCM is considered a disease of the sarcomere owing to the large number of mutations in genes encoding sarcomeric proteins. The riddle lies in discovering how these mutations lead to disease. As a result, treatments to prevent and/or treat HCM are limited to invasive surgical myectomies or ablations. The A31P variant of cardiac myosin binding protein-C, encoded by Next Generation Whole Genome sequencing was performed using DNA isolated from peripheral blood of a Maine Coon with cardiomyopathy that tested negative for the In summary, we are the first to demonstrate the association between Show less

Phosphorylation of cardiac myosin binding protein-C (cMyBP-C) accelerates cardiac contractility. However, the mechanisms by which cMyBP-C phosphorylation increases contractile kinetics have not been fully elucidated. In this study, we tested the hypothesis that phosphorylation of cMyBP-C releases myosin heads from the inhibited super-relaxed state (SRX), thereby determining the fraction of myosin available for contraction. Mice with various alanine (A) or aspartic acid (D) substitutions of the three main phosphorylatable serines of cMyBP-C (serines 273, 282, and 302) were used to address the association between cMyBP-C phosphorylation and SRX. Single-nucleotide turnover in skinned ventricular preparations demonstrated that phosphomimetic cMyBP-C destabilized SRX, whereas phospho-ablated cMyBP-C had a stabilizing effect on SRX. Strikingly, phosphorylation at serine 282 site was found to play a critical role in regulating the SRX. Treatment of WT preparations with protein kinase A (PKA) reduced the SRX, whereas, in nonphosphorylatable cMyBP-C preparations, PKA had no detectable effect. Mice with stable SRX exhibited reduced force production. Phosphomimetic cMyBP-C with reduced SRX exhibited increased rates of tension redevelopment and reduced binding to myosin. We also used recombinant myosin subfragment-2 to disrupt the endogenous interaction between cMyBP-C and myosin and observed a significant reduction in the population of SRX myosin. This peptide also increased force generation and rate of tension redevelopment in skinned fibers. Taken together, this study demonstrates that the phosphorylation-dependent interaction between cMyBP-C and myosin is a determinant of the fraction of myosin available for contraction. Furthermore, the binding between cMyBP-C and myosin may be targeted to improve contractile function. Show less

Cardiac myosin binding protein-C (cMyBP-C) phosphorylation is essential for normal heart function and protects the heart from ischemia-reperfusion (I/R) injury. It is known that protein kinase-A (PKA)-mediated phosphorylation of cMyBP-C prevents I/R-dependent proteolysis, whereas dephosphorylation of cMyBP-C at PKA sites correlates with its degradation. While sites on cMyBP-C associated with phosphorylation and proteolysis co-localize, the mechanisms that link cMyBP-C phosphorylation and proteolysis during cardioprotection are not well understood. Therefore, we aimed to determine if abrogation of cMyBP-C proteolysis in association with calpain, a calcium-activated protease, confers cardioprotection during I/R injury. Calpain is activated in both human ischemic heart samples and ischemic mouse myocardium where cMyBP-C is dephosphorylated and undergoes proteolysis. Moreover, cMyBP-C is a substrate for calpain proteolysis and cleaved by calpain at residues 272-TSLAGAGRR-280, a domain termed as the calpain-target site (CTS). Cardiac-specific transgenic (Tg) mice in which the CTS motif was ablated were bred into a cMyBP-C null background. These Tg mice were conclusively shown to possess a normal basal structure and function by analysis of histology, electron microscopy, immunofluorescence microscopy, Q-space MRI of tissue architecture, echocardiography, and hemodynamics. However, the genetic ablation of the CTS motif conferred resistance to calpain-mediated proteolysis of cMyBP-C. Following I/R injury, the loss of the CTS reduced infarct size compared to non-transgenic controls. Collectively, these findings demonstrate the physiological significance of calpain-targeted cMyBP-C proteolysis and provide a rationale for studying inhibition of calpain-mediated proteolysis of cMyBP-C as a therapeutic target for cardioprotection. Show less

Objective- SAA (serum amyloid A) is a family of acute-phase reactants that have proinflammatory and proatherogenic activities. SAA is more lipophilic than apoA-I (apolipoprotein A-I), and during an acute-phase response, <10% of plasma SAA is found lipid-free. In most reports, SAA is found exclusively associated with high-density lipoprotein; however, we and others have reported SAA on apoB (apolipoprotein B)-containing lipoproteins in both mice and humans. The goal of this study was to determine whether SAA is an exchangeable apolipoprotein. Approach and Results- Delipidated human SAA was incubated with SAA-free human lipoproteins; then, samples were reisolated by fast protein liquid chromatography, and SAA analyzed by ELISA and immunoblot. Both in vitro and in vivo, we show that SAA associates with any lipoprotein and does not remain in a lipid-free form. Although SAA is preferentially found on high-density lipoprotein, it can exchange between lipoproteins. In the presence of CETP (cholesterol ester transfer protein), there is greater exchange of SAA between lipoproteins. Subjects with diabetes mellitus, but not those with metabolic syndrome, showed altered SAA lipoprotein distribution postprandially. Proteoglycan-mediated lipoprotein retention is thought to be an underlying mechanism for atherosclerosis development. SAA has a proteoglycan-binding domain. Lipoproteins containing SAA had increased proteoglycan binding compared with SAA-free lipoproteins. Conclusions- Thus, SAA is an exchangeable apolipoprotein and increases apoB-containing lipoproteins' proteoglycan binding. We and others have previously reported the presence of SAA on low-density lipoprotein in individuals with obesity, diabetes mellitus, and metabolic syndrome. We propose that the presence of SAA on apoB-containing lipoproteins may contribute to cardiovascular disease development in these populations. Show less

Over 1,500 gene mutations are known to cause hypertrophic cardiomyopathy (HCM). Previous studies suggest that cardiac β-myosin heavy chain (MYH7) gene mutations are commonly associated with a more severe phenotype, compared to cardiac myosin binding protein-C (MYBPC3) gene mutations with milder phenotype, incomplete penetrance and later age of onset. Compound mutations can worsen the phenotype. This study aimed to validate these comparative differences in a large cohort of individuals and families with HCM. We performed genome-phenome correlation among 80 symptomatic HCM patients, 35 asymptomatic carriers and 35 non-carriers, using an 18-gene clinical diagnostic HCM panel. A total of 125 mutations were identified in 14 genes. MYBPC3 and MYH7 mutations contributed to 50.0% and 24.4% of the HCM patients, respectively, suggesting that MYBPC3 mutations were the most frequent cause of HCM in our cohort. Double mutations were found in only nine HCM patients (7.8%) who were phenotypically indistinguishable from single-mutation carriers. Comparisons of clinical parameters of MYBPC3 and MYH7 mutants were not statistically significant, but asymptomatic carriers had high left ventricular ejection fraction and diastolic dysfunction when compared to non-carriers. The presence of double mutations increases the risk for symptomatic HCM with no change in severity, as determined in this study subset. The pathologic effects of MYBPC3 and MYH7 were found to be independent of gene mutation location. Furthermore, HCM pathology is independent of protein domain disruption in both MYBPC3 and MYH7. These data provide evidence that MYBPC3 mutations constitute the preeminent cause of HCM and that they are phenotypically indistinguishable from HCM caused by MYH7 mutations. Show less

The "super-relaxed state" (SRX) of myosin represents a 'reserve' of motors in the heart. Myosin heads in the SRX are bound to the thick filament and have a very low ATPase rate. Changes in the SRX are likely to modulate cardiac contractility. We previously demonstrated that the SRX is significantly reduced in mouse cardiomyocytes lacking cardiac myosin binding protein-C (cMyBP-C). Here, we report the effect of mutations in the cMyBP-C gene (MYBPC3) using samples from human patients with hypertrophic cardiomyopathy (HCM). Left ventricular (LV) samples from 11 HCM patients were obtained following myectomy surgery to relieve LV outflow tract obstruction. HCM samples were genotyped as either MYBPC3 mutation positive (MYBPC3mut) or negative (HCMsmn) and were compared to eight non-failing donor hearts. Compared to donors, only MYBPC3mut samples display a significantly diminished SRX, characterised by a decrease in both the number of myosin heads in the SRX and the lifetime of ATP turnover. These changes were not observed in HCMsmn samples. There was a positive correlation (p < 0.01) between the expression of cMyBP-C and the proportion of myosin heads in the SRX state, suggesting cMyBP-C modulates and maintains the SRX. Phosphorylation of the myosin regulatory light chain in MYBPC3mut samples was significantly decreased compared to the other groups, suggesting a potential mechanism to compensate for the diminished SRX. We conclude that by altering both contractility and sarcomeric energy requirements, a reduced SRX may be an important disease mechanism in patients with MYBPC3 mutations. Show less

Cardiac myosin binding protein-C (cMyBP-C) is a structural and regulatory component of cardiac thick filaments. It is observed in electron micrographs as seven to nine transverse stripes in the central portion of each half of the A band. Its C-terminus binds tightly to the myosin rod and contributes to thick filament structure, while the N-terminus can bind both myosin S2 and actin, influencing their structure and function. Mutations in the MYBPC3 gene (encoding cMyBP-C) are commonly associated with hypertrophic cardiomyopathy (HCM). In cardiac cells there exists a population of myosin heads in the super-relaxed (SRX) state, which are bound to the thick filament core with a highly inhibited ATPase activity. This report examines the role cMyBP-C plays in regulating the population of the SRX state of cardiac myosin by using an assay that measures single ATP turnover of myosin. We report a significant decrease in the proportion of myosin heads in the SRX state in homozygous cMyBP-C knockout mice, however heterozygous cMyBP-C knockout mice do not significantly differ from the wild type. A smaller, non-significant decrease is observed when thoracic aortic constriction is used to induce cardiac hypertrophy in mutation negative mice. These results support the proposal that cMyBP-C stabilises the thick filament and that the loss of cMyBP-C results in an untethering of myosin heads. This results in an increased myosin ATP turnover, further consolidating the relationship between thick filament structure and the myosin ATPase. Show less

Atherosclerosis is the major cause of coronary artery disease (CAD), and oxidized LDL (oxLDL) is believed to play a key role in the initiation of the atherosclerotic process. Recent studies show that inflammation and autoimmune reactions are also relevant in atherosclerosis. In this study, we examined the association of antibodies against oxLDL (anti-oxLDL) with the severity of CAD in 558 Women's Ischemia Syndrome Evaluation (WISE) study samples (465 whites; 93 blacks) determined by coronary stenosis (< 20%, 20%-49%, > 50% stenosis). We also examined the relationship of anti-oxLDL with serum lipid levels and nine candidate genes including APOE, APOH, APOA5, LPL, LRP1, HL, CETP, PON1, and OLR1. IgM anti-oxLDL levels were significantly higher in the >20% stenosis group than in the ≥ 20% stenosis group in whites (0.69 ± 0.02 vs. 0.64 ± 0.01, respectively; P = 0.02). IgM anti-oxLDL levels correlated significantly with total cholesterol (r² = 0.01; P = 0.03) and LDL cholesterol (r² = 0.017; P = 0.004) in whites. Multiple regression analysis revealed a suggestive association of LPL/S447X single-nucleotide polymorphism (SNP) with both IgG anti-oxLDL (P = 0.02) and IgM anti-oxLDL (P = 0.07), as well as between IgM anti-oxLDL and the OLR1/3'UTR SNP (P = 0.020). Our data suggest that higher IgM anti-oxLDL levels may provide protection against coronary stenosis and that genetic variation in some candidate genes are determinants of anti-oxLDL levels. Show less

This study investigated the effects of perinatal dietary omega-3 (n-3) fatty acid depletion and subsequent repletion on the expression of genes that regulate long-chain (LC) polyunsaturated fatty acid biosynthesis in rat liver and brain. It was hypothesized that chronic n-3 fatty acid deficiency would increase liver Fads1 and Fads2 messenger RNA (mRNA) expression/activity and that n-3 fatty acid repletion would normalize this response. Adult rats fed the n-3-free diet during perinatal development exhibited significantly lower erythrocyte, liver, and frontal cortex LCn-3 fatty acid composition and reciprocal elevations in LC omega-6 (n-6) fatty acid composition compared with controls (CONs) and repleted rats. Liver Fads2, but not Fads1, Elovl2, or Elovl5, mRNA expression was significantly greater in n-3-deficient (DEF) rats compared with CONs and was partially normalized in repleted rats. The liver 18:3n-6/18:2n-6 ratio, an index of delta6-desturase activity, was significantly greater in DEF rats compared with CON and repleted rats and was positively correlated with Fads2 mRNA expression among all rats. The liver 18:3n-6/18:2n-6 ratio, but not Fads2 mRNA expression, was also positively correlated with erythrocyte and frontal cortex LCn-6 fatty acid compositions. Neither Fads1 or Fads2 mRNA expression was altered in brain cortex of DEF rats. These results confirm previous findings that liver, but not brain, delta6-desaturase expression and activity indices are negatively regulated by dietary n-3 fatty acids. Show less

Polyunsaturated fatty acids (PUFA), a lipid family comprised of omega-3 (n-3) and n-6 fatty acids, are a critical component of cellular membranes, and recent in vitro studies have found that antipsychotic medications up-regulate genes responsible for PUFA biosynthesis. To evaluate this effect in vivo, rats were treated with risperidone (1.5, 3, 6mg/kg/day), paliperidone (1.5, 3, 6mg/kg/day), olanzapine (2.5, 5, 10mg/kg/day), quetiapine (5, 10, 20mg/kg/day), haloperidol (1, 3mg/kg/day) or vehicle through their drinking water for 40day. Effects on liver Fads1, Fads2, Elovl2, and Elovl5 mRNA expression, plasma indices of n-3 (plasma 22:6/18:3 and 20:5/18:3 ratios) and n-6 (plasma 20:4/18:2 and 20:3/18:2 ratios) biosynthesis, and peripheral (erythrocyte, heart) and central (frontal cortex) membrane PUFA composition were determined. Only risperidone and its metabolite paliperidone significantly and selectively up-regulated liver delta-6 desaturase (Fads2) mRNA expression, and robustly increased plasma indices of n-3 and n-6 fatty acid biosynthesis. In risperidone- and paliperidone-treated rats, plasma indices of n-3 and n-6 fatty acid biosynthesis were all positively correlated with liver Fads2 mRNA expression, but not Fads1, Elovl2, or Elovl5 mRNA expression. All antipsychotics at specific doses increased erythrocyte docosahexaenoic acid (DHA, 22:6n-3) composition, and all except quetiapine increased arachidonic acid (AA, 20:4n-6) composition. Risperidone, paliperidone, and olanzapine increased heart DHA and AA composition, and no antipsychotic altered frontal cortex DHA or AA composition. These in vivo data demonstrate that augmentation of PUFA biosynthesis is not common to all antipsychotic medications, and that risperidone and paliperidone uniquely increase delta-6 desaturase (Fads2) mRNA expression and most robustly increase PUFA biosynthesis and peripheral membrane composition. Show less

Major depressive disorder (MDD) is associated with central and peripheral deficits in long-chain polyunsaturated fatty acids (LC-PUFA), particularly those in the omega-3 fatty acid family. However, the etiology of these deficits remains poorly understood, and there is currently little known about the expression of genes that mediate fatty acid biosynthesis in MDD patients. The expression of FADS1 (Δ5 desaturase), FADS2 (Δ6 desaturase), HELO1 [ELOVL5] (elongase), PEX19 (peroxisome), and SCD (stearoyl-CoA desaturase [Δ9 desaturase]) was determined in the postmortem prefrontal cortex of MDD patients (n=10) and non-psychiatric controls (n=10) by real-time reverse transcriptase polymerase chain reaction (RT-PCR). After correcting for multiple comparisons, FADS1 mRNA expression was significantly lower in MDD patients relative to controls (-27%, p=0.009), and there were trends for lower expression of FADS2 (-30%, p=0.07), HELO1 (-37%, p=0.02), and SCD (-43%, p=0.02). PEX19 mRNA expression did not differ between controls and MDD patients (-2%, p=0.92). There were no significant gender effects, and relative reductions in FADS1, HELO1, and SCD expression were greater in patients that did not commit suicide compared with patients that did commit suicide. The sample size was small, and all MDD patients were receiving antidepressant medications. Principal genes involved in LC-PUFA and monounsaturated fatty acid biosynthesis are down-regulated in the postmortem prefrontal cortex of MDD patients. Additional studies are needed to replicate and extend these findings in a larger sample that includes antidepressant-free MDD patients. Show less

Although evidence suggests that a dysregulation in polyunsaturated fatty acid (PUFA) homeostasis may contribute to the pathoetiology of bipolar disorder (BD), there is currently nothing known about the expression of genes that mediate long-chain PUFA biosynthesis in BD patients. In the present study we determined FADS1 (Δ5 desaturase), FADS2 (Δ6 desaturase), HELO1 [ELOVL5] (elongase), PEX19 (peroxisome), and SCD (stearoyl-CoA desaturase [Δ9 desaturase]) mRNA expression in the postmortem prefrontal cortex of non-psychiatric controls (n = 12) and BD patients (n = 12) by real-time reverse transcriptase polymerase chain reaction (RT-PCR). Changes in the activities of corresponding enzyme products were estimated from fatty acid product: precursor ratios. After correcting for multiple comparisons, FADS2 mRNA expression was significantly greater in BD patients relative to controls (+27%, p = 0.004). Indices of Δ6 desaturase activity, including 20:4/18:2 (+18%, p = 0.15) and 20:3/18:2 (+12%, p = 0.25) ratios, were numerically, but not significantly, greater in BD patients relative to controls. There were no significant group differences in FADS1 (+17%, p = 0.32), HELO1 (+4%, p = 0.81), PEX19 (-2%, p = 0.91), and SCD (+4%, p = 0.85) mRNA expression, or indices of Δ5 desaturase (+5%, 0.59), elongase (+3%, p = 0.62), and stearoyl-CoA desaturase (-11%, p = 0.10) activities. These preliminary findings demonstrate that FADS2 mRNA expression is significantly and selectively elevated in the prefrontal cortex of BD patients, and may contribute to dysregulated central PUFA biosynthesis and pro-inflammatory signaling implicated in the pathophysiology of BD. Show less

Although emerging evidence suggests that schizophrenia (SZ) is associated with peripheral and central polyunsaturated fatty acid (PUFA) deficits, there is currently nothing known about the expression of genes that mediate PUFA biosynthesis in SZ patients. Here we determined Delta5 desaturase (FADS1), Delta6 desaturase (FADS2), elongase (HELO1 [ELOVL5]), peroxisomal (PEX19), and Delta9 desaturase (stearoyl-CoA desaturase, SCD) mRNA expression, and relevant fatty acid product:precursor ratios as estimates of enzyme activities, in the postmortem prefrontal cortex (PFC) of patients with SZ (n=20) and non-psychiatric controls (n=20). After correction for multiple comparisons, FADS2 mRNA expression was significantly greater in SZ patients relative to controls (+36%, p=0.002), and there was a positive trend found for FADS1 (+26%, p=0.15). No differences were found for HELO1 (+10%, p=0.44), PEX19 (+12%, p=0.44), or SCD (-6%, p=0.85). Both male (+34%, p=0.02) and female (+42%, p=0.02) SZ patients exhibited greater FADS2 mRNA expression relative to same-gender controls. Drug-free SZ patients (+37%, p=0.02), and SZ patients treated with typical (+40%, p=0.002) or atypical (+31%, p=0.04) antipsychotics, exhibited greater FADS2 mRNA expression relative to controls. Consistent with increased Delta6 desaturase activity, SZ patients exhibited a greater 20:3/18:2 ratio (+20%, p=0.03) and a positive trend was found for 20:4/18:2 (+13%, p=0.07). These data demonstrate abnormal, potentially compensatory, elevations in Delta6 desaturase (FADS2) expression in the PFC of SZ patients that are independent of gender and antipsychotic medications. Greater Delta6 desaturase expression and activity could have implications for central prostaglandin synthesis and proinflammatory signaling. Show less

Juvenile neuronal ceroid lipofuscinosis (JNCL) is due to mutations in the CLN3 gene. We previously determined that CLN3 protein harbors a highly conserved motif, VYFAE, necessary for its impact on cell growth and apoptosis. Using molecular modeling we demonstrated that this motif is embedded in a stretch of amino acids that is homologous to and structurally compatible with a galactosylceramide (GalCer) binding domain. This domain is present in the V3 loop of the HIV-1 gp120 envelope protein, beta-amyloid protein, and the infectious form of prionic protein, and defines a binding site for lipid rafts. We determined the subcellular localization of CLN3 in different cell systems including human neurons, primary rat hippocampal neurons, normal human fibroblasts, and JNCL fibroblasts homozygous for the 1.02 kb deletion in genomic DNA. Wild-type CLN3 protein was present within Golgi, lipid rafts in the plasma membrane, and early recycling endosomes, but not late endosomes/lysosomes. Wild-type CLN3 internalized from the plasma membrane to the Golgi via Rab4- and Rab11-positive recycling endosomes. Wild-type CLN3 co-localized with GalCer in the Golgi and in lipid rafts at the plasma membrane in normal cells. Neither mutant CLN3 protein nor GalCer were found at the plasma membrane in JNCL fibroblasts. Mutant CLN3p was retained within the Golgi and partially mis-localized to lysosomes, failing to reach recycling endosomes, plasma membrane, or lipid rafts. These studies identify a novel CLN3 domain that may dictate localization and function of CLN3. Show less