Accumulation Of Ceroid Lipofuscin Research Articles

Ppt1-deficiency dysregulates lysosomal Ca++ homeostasis contributing to pathogenesis in a mouse model of CLN1 disease.

Inactivating mutations in the PPT1 gene encoding palmitoyl-protein thioesterase-1 (PPT1) underlie the CLN1 disease, a devastating neurodegenerative lysosomal storage disorder. The mechanism of pathogenesis underlying CLN1 disease has remained elusive. PPT1 is a lysosomal enzyme, which catalyzes the removal of palmitate from S-palmitoylated proteins (constituents of ceroid lipofuscin) facilitating their degradation and clearance by lysosomal hydrolases. Thus, it has been proposed that Ppt1-deficiency leads to lysosomal accumulation of ceroid lipofuscin leading to CLN1 disease. While S-palmitoylation is catalyzed by palmitoyl acyltransferases (called ZDHHCs), palmitoyl-protein thioesterases (PPTs) depalmitoylate these proteins. We sought to determine the mechanism by which Ppt1-deficiency may impair lysosomal degradative function leading to infantile neuronal ceroid lipofuscinosis pathogenesis. Here, we report that in Ppt1-/- mice, which mimic CLN1 disease, low level of inositol 3-phosphate receptor-1 (IP3R1) that mediates Ca++ transport from the endoplasmic reticulum to the lysosome dysregulated lysosomal Ca++ homeostasis. Intriguingly, the transcription factor nuclear factor of activated T-cells, cytoplasmic 4 (NFATC4), which regulates IP3R1-expression, required S-palmitoylation for trafficking from the cytoplasm to the nucleus. We identified two palmitoyl acyltransferases, ZDHHC4 and ZDHHC8, which catalyzed S-palmitoylation of NFATC4. Notably, in Ppt1-/- mice, reduced ZDHHC4 and ZDHHC8 levels markedly lowered S-palmitoylated NFATC4 (active) in the nucleus, which inhibited IP3R1-expression, thereby dysregulating lysosomal Ca++ homeostasis. Consequently, Ca++ -dependent lysosomal enzyme activities were markedly suppressed. Impaired lysosomal degradative function impaired autophagy, which caused lysosomal storage of undigested cargo. Importantly, IP3R1-overexpression in Ppt1-/- mouse fibroblasts ameliorated this defect. Our results reveal a previously unrecognized role of Ppt1 in regulating lysosomal Ca++ homeostasis and suggest that this defect contributes to pathogenesis of CLN1 disease.

S1618 The Need for Vigilance: A Rare Association of Pancreatic Atrophy With Hermansky-Pudlak Syndrome

Introduction: Hermansky-Pudlak Syndrome (HPS) is an autosomal recessive disorder, which is characterized by oculocutaneous albinism, bleeding disorder, and immunodefiecencies. HPS can involve multiple organs of the body and can cause serious complications in the later part of the disease. Major complications associated with this genetic disorder are granulomatous colitis and pulmonary fibrosis. Here in, we report a case of a young male with classic symptoms of HPS with renal, pulmonary, and pancreatic complications. Case Description/Methods: A 32-year-old man presented with a dry cough and shortness of breath. On clinical examination, he was in respiratory distress with diffuse bilateral inspiratory crackles. Hypopigmentation of hair and skin, clubbing in all fingers, were evident. The eye examination revealed nystagmus of both eyes. Hypo pigmented fundus and hypoplastic fovea were evident on fundoscopic examination. Chest Imaging was suggestive of interstitial lung disease with a restrictive pattern in spirometry. Blood chemistry was significant for elevated blood urea and serum creatinine. On further reviewing of his medical records, we found that his symptoms were ongoing since 15 years with worsening photophobia, decreased vision, recurrent urinary tract and ear infections, respiratory distress and worsening kidney function. Another interesting finding in the CT scan of the abdomen was extrahepatic portal hypertension and atrophy of the body and tail of the pancreas. He was diagnosed with HPS based on the above findings. Discussion: Pathogenesis of HPS can be attributed to mutations in the genes responsible for lysosome-related organelle(LRO) function in melanocytes and platelets, leading to albinism and bleeding disorder respectively. Besides typical clinical features of HPS with respiratory and renal complications, our patient also had portal hypertension and atrophy of the head and neck of the pancreas. As per our literature review, ours is the first case reporting pancreatic involvement in HPS. The mechanism behind pancreatic atrophy is unknown. A possible explanation can be the accumulation of ceroid lipofuscin, an amorphous lipid-protein complex, in the biliary or pancreatic duct or within the pancreatic parenchyma, which could cause pancreatic atrophy in the same way as ceroid lipofuscin causing pulmonary fibrosis. The purpose of our case report is to emphasize the possibility of unusual complications of HPS to facilitate the timely intervention to halt the progression of complications.

Using the social amoeba Dictyostelium to study the functions of proteins linked to neuronal ceroid lipofuscinosis.

Neuronal ceroid lipofuscinosis (NCL), also known as Batten disease, is a debilitating neurological disorder that affects both children and adults. Thirteen genetically distinct genes have been identified that when mutated, result in abnormal lysosomal function and an excessive accumulation of ceroid lipofuscin in neurons, as well as other cell types outside of the central nervous system. The NCL family of proteins is comprised of lysosomal enzymes (PPT1/CLN1, TPP1/CLN2, CTSD/CLN10, CTSF/CLN13), proteins that peripherally associate with membranes (DNAJC5/CLN4, KCTD7/CLN14), a soluble lysosomal protein (CLN5), a protein present in the secretory pathway (PGRN/CLN11), and several proteins that display different subcellular localizations (CLN3, CLN6, MFSD8/CLN7, CLN8, ATP13A2/CLN12). Unfortunately, the precise functions of many of the NCL proteins are still unclear, which has made targeted therapy development challenging. The social amoeba Dictyostelium discoideum has emerged as an excellent model system for studying the normal functions of proteins linked to human neurological disorders. Intriguingly, the genome of this eukaryotic soil microbe encodes homologs of 11 of the 13 known genes linked to NCL. The genetic tractability of the organism, combined with its unique life cycle, makes Dictyostelium an attractive model system for studying the functions of NCL proteins. Moreover, the ability of human NCL proteins to rescue gene-deficiency phenotypes in Dictyostelium suggests that the biological pathways regulating NCL protein function are likely conserved from Dictyostelium to human. In this review, I will discuss each of the NCL homologs in Dictyostelium in turn and describe how future studies can exploit the advantages of the system by testing new hypotheses that may ultimately lead to effective therapy options for this devastating and currently untreatable neurological disorder.

Juvenile neuronal ceroid-lipofuscinosis with hypertrophic cardiomyopathy and left ventricular noncompaction: a case report.

We report a 17-year-old female with juvenile neuronal ceroid-lipofuscinosis (NCL) accompanied by hypertrophic cardiomyopathy (HCM) and left ventricular noncompaction (LVNC). Within our knowledge, this is the first reported case of juvenile NCL with LVNC, and the youngest case of HCM diagnosed by ultrasound. Juvenile NCL is a progressive hereditary disease involving multi-organ accumulation of ceroid-lipofuscin; its resulting complications require prompt attention. Due to its relative rarity, its cardiac involvement is not well known. Based on findings from this patient and related juvenile NCL cases, the risk of cardiac involvement tends to increase with age; a high frequency of ventricular hypertrophy has been reported in patients aged older than 20 years of age. Medical progress and comprehensive care have led to longer survival in patients with juvenile NCL, which likely increases the incidence of cardiac involvement. In relation to HCM in other metabolic disorders, attention should be paid to arrhythmias, including repolarization disturbances, sinus node dysfunction and ventricular tachycardia. LVNC is a cardiomyopathy characterized by prominent left ventricular trabeculae and deep intratrabecular recesses, which are associated with diastolic or systolic dysfunction, thromboembolic complications and arrhythmias. From ours and other case reports, we recommend regular follow-up of NCL patients as follows: echocardiography to estimate cardiomyopathy, Holter monitoring to identify arrhythmias, and computed tomography to detect thrombosis from both ventricles. The mechanism of the HCM and LVNC associated with juvenile NCL remains unclear. Our case requires careful follow-up. Prospective studies of the cardiac involvement in juvenile NCL are necessary to further elucidate its pathomechanism.

The Batten disease gene CLN3 confers resistance to endoplasmic reticulum stress induced by tunicamycin

Mutations in CLN3 gene cause juvenile neuronal ceroid lipofuscinosis (JNCL or Batten disease), an early-onset neurodegenerative disorder that is characterized by the accumulation of ceroid lipofuscin within lysosomes. The function of the CLN3 protein remains unclear and is presumed to be related to Endoplasmic reticulum (ER) stress. To investigate the function of CLN3 in the ER stress signaling pathway, we measured proliferation and apoptosis in cells transfected with normal and mutant CLN3 after treatment with the ER stress inducer tunicamycin (TM). We found that overexpression of CLN3 was sufficient in conferring increased resistance to ER stress. Wild-type CLN3 protected cells from TM-induced apoptosis and increased cell proliferation. Overexpression of wild-type CLN3 enhanced expression of the ER chaperone protein, glucose-regulated protein 78 (GRP78), and reduced expression of the proapoptotic protein CCAAT/-enhancer-binding protein homologous protein (CHOP). In contrast, overexpression of mutant CLN3 or siRNA knockdown of CLN3 produced the opposite effect. Together, our data suggest that the lack of CLN3 function in cells leads to a failure of management in the response to ER stress and this may be the key deficit in JNCL that causes neuronal degeneration.

Hermansky-Pudlak syndrome: A case report

Hermansky-Pudlak syndrome (HPS) is a rare autosomal recessive disorder, which results in oculocutaneous albinism, bleeding disorders, and storage of abnormal fat protein compound (liposomal accumulation of ceroid lipofuscin). The major complications of this disorder are pulmonary fibrosis (PF) and colitis. This is a case report of an HPS patient with PF.

肥大型心筋症と左室緻密化障害が判明した若年型neuronal ceroid-lipofuscinosisの1例

We report a 17-year-old female with juvenile neuronal ceroid-lipofuscinosis (NCL) accompanied by hypertrophic cardiomyopathy (HCM) and left ventricular noncompaction (LVNC). Within our knowledge, this is the first reported case of juvenile NCL with LVNC, and the youngest case of HCM diagnosed by ultrasound. Juvenile NCL is a progressive hereditary disease involving multi-organ accumulation of ceroid-lipofuscin; its resulting complications require prompt attention. Due to its relative rarity, its cardiac involvement is not well known. Based on findings from this patient and related juvenile NCL cases, the risk of cardiac involvement tends to increase with age; a high frequency of ventricular hypertrophy has been reported in patients aged older than 20 years of age. Medical progress and comprehensive care have led to longer survival in patients with juvenile NCL, which likely increases the incidence of cardiac involvement. In relation to HCM in other metabolic disorders, attention should be paid to arrhythmias, including repolarization disturbances, sinus node dysfunction and ventricular tachycardia. LVNC is a cardiomyopathy characterized by prominent left ventricular trabeculae and deep intratrabecular recesses, which are associated with diastolic or systolic dysfunction, thromboembolic complications and arrhythmias. From ours and other case reports, we recommend regular follow-up of NCL patients as follows: echocardiography to estimate cardiomyopathy, Holter monitoring to identify arrhythmias, and computed tomography to detect thrombosis from both ventricles. The mechanism of the HCM and LVNC associated with juvenile NCL remains unclear. Our case requires careful follow-up. Prospective studies of the cardiac involvement in juvenile NCL are necessary to further elucidate its pathomechanism.

Hermansky-Pudlak Syndrome: Health Care Throughout Life

Hermansky-Pudlak syndrome (HPS) is a rare autosomal recessive disease that displays genetic heterogeneity; there are 9 known subtypes. HPS is characterized by oculocutaneous albinism, a platelet storage pool deficiency and resultant bleeding diathesis, and lysosomal accumulation of ceroid lipofuscin. Patients with HPS, specifically those with the genotypes HPS-1, HPS-2, or HPS-4, are predisposed to interstitial lung disease. In addition, some patients with HPS develop granulomatous colitis. Optimal health care requires a thorough knowledge of the unique health risks and functional limitations associated with this syndrome.

Hermansky-Pudlak syndrome (HPS5) in a nonagenarian

Hermansky-Pudlak syndrome (HPS) is an autosomal-recessive disorder clinically characterized by oculocutaneous albinism, bleeding diatheses, and lysosomal accumulation of ceroid lipofuscin, which in some cases may cause granulomatous colitis and pulmonary fibrosis. Any of these complications could result in a shortened life span for patients with HPS. We report a 92-year-old man with HPS 5 who, to our knowledge, is the oldest patient with HPS documented in the literature. This report highlights the importance of typing HPS to counsel patients regarding disease prognosis.

Granulomatous Enterocolitis Associated with Hermansky-Pudlak Syndrome

Hermansky-Pudlak syndrome (HPS) is a rare autosomal recessive disorder. It consists of a triad of tyrosinase-positive oculocutaneous albinism (Ty-pos OCA), bleeding diathesis resulting from platelet dysfunction, and systemic complications associated with accumulation of ceroid lipofuscin. Many patients are from a small area in northwestern Puerto Rico. HPS has been associated with granulomatous enterocolitis in up to 20% of affected patients. It is not known whether this granulomatous colitis is a part of the syndrome, or represents an independent but associated process, such as Crohn's disease. This colitis can be severe, and has been reported to be poorly responsive to medical therapies including sulfasalazine, mesalamine, steroids, and metronidazole. We report a series of four patients with refractory enterocolitis in the setting of HPS who were treated at Mount Sinai Hospital between 1998 and 2005. A trial of infliximab was attempted in all four, and produced a complete response in two. Many phenotypic and pathologic similarities exist between granulomatous enterocolitis in HPS and Crohn's disease. However, it is unclear whether the granulomatous enterocolitis in HPS is because of ceroid deposition or reflects the coexistence of Crohn's disease and HPS. The occurrence of ileal involvement and perianal fistulization in our cases suggests that in at least some instances, HPS and Crohn's disease are truly associated.

Ocular Pathologic Features of Hermansky-Pudlak Syndrome Type 1 in an Adult

Hermansky-Pudlak syndrome (HPS) is a rare autosomal recessive disease, characterized by a triad of oculocutaneous albinism (OCA), bleeding diathesis due to deficiency of dense bodies in platelets, and lysosomal accumulation of ceroid lipofuscin.1 Seven genetic subtypes of HPS have been identified in humans2; HPS1 on chromosome 10q23 is the most common and represents a founder effect in northwest Puerto Rico.1 The clinical features of HPS and its ophthalmic involvement3,4 are well documented, but no ocular histopathology has been published (to our knowledge). Herein, we describe the ocular histopathology of an adult patient with HPS type 1 (HPS-1).

Neurological aspects of osteopetrosis.

The osteopetroses are caused by reduced activity of osteoclasts which results in defective remodelling of bone and increased bone density. They range from a devastating neurometabolic disease, through severe malignant infantile osteopetrosis (OP) to two more benign conditions principally affecting adults [autosomal dominant OP (ADO I and II)]. In many patients the disease is caused by defects in either the proton pump [the a3 subunit of vacuolar-type H(+)-ATPase, encoded by the gene variously termed ATP6i or TCIRG1] or the ClC-7 chloride channel (ClCN7 gene). These pumps are responsible for acidifying the bone surface beneath the osteoclast. Although generally thought of as bone diseases, the most serious consequences of the osteopetroses are seen in the nervous system. Cranial nerves, blood vessels and the spinal cord are compressed by either gradual occlusion or lack of growth of skull foramina. Most patients with OP have some degree of optic atrophy and many children with severe forms of autosomal recessive OP are rendered blind; optic decompression is frequently attempted to prevent the latter. Auditory, facial and trigeminal nerves may also be affected, and hydrocephalus can develop. Stenosis of both arterial supply (internal carotid and vertebral arteries) and venous drainage may occur. The least understood form of the disease is neuronopathic OP [OP and infantile neuroaxonal dystrophy, MIM (Mendelian inheritance in man) 600329] which causes rapid neurodegeneration and death within the first year. Although characterized by the finding of widespread axonal spheroids and accumulation of ceroid lipofuscin, the biochemical basis of this disease remains unknown. The neurological complications of this disease and other variants are presented in the context of the latest classification of the disease.

CLC-3 deficiency leads to phenotypes similar to human neuronal ceroid lipofuscinosis.

CLC-3 is a member of the CLC chloride channel family and is widely expressed in mammalian tissues. To determine the physiological role of CLC-3, we generated CLC-3-deficient mice (Clcn3-/- ) by targeted gene disruption. Together with developmental retardation and higher mortality, the Clcn3-/- mice showed neurological manifestations such as blindness, motor coordination deficit, and spontaneous hyperlocomotion. In histological analysis, the Clcn3-/- mice showed a pattern of progressive degeneration of the retina, hippocampus and ileal mucosa, which resembled the phenotype observed in cathepsin D knockout mice. The defect of cathepsin D results in a lysosomal accumulation of ceroid lipofuscin containing the mitochondrial F1F0 ATPase subunit c. In immunohistochemistry and Western blot analysis, we found that the subunit c was heavily accumulated in the lysosome of Clcn3-/- mice. Furthermore, we detected an elevation in the endosomal pH of the Clcn3-/- mice. These results indicated that the neurodegeneration observed in the Clcn3-/- mice was caused by an abnormality in the machinery which degrades the cellular protein and was associated with the phenotype of neuronal ceroid lipofuscinosis (NCL). The elevated endosomal pH could be an important factor in the pathogenesis of NCL.

Involvement of Nitric Oxide Released from Microglia–Macrophages in Pathological Changes of Cathepsin D-Deficient Mice

Cathepsin D (CD) deficiency has been shown to induce ceroid-lipofuscin storage in lysosomes of mouse CNS neuron (Koike et al., 2000). To understand the behavior of microglial cells corresponding to these neuronal changes, CD-deficient (CD-/-) mice, which die at approximately postnatal day (P) 25 by intestinal necrosis, were examined using morphological as well as biochemical approaches. Light and electron microscopic observations revealed that microglia showing large round cell bodies with few processes appeared in the cerebral cortex and thalamus after P16. At P24, microglia often encircled neurons that were occupied with autolysosomes, indicating increased phagocytic activity. These morphologically transformed microglia markedly expressed inducible nitric oxide synthase (iNOS), which was also detected in the intestine of the mice. To assess the role of microglial nitric oxide (NO) in neuropathological changes in CD-/- mice, l-N(G)-nitro-arginine methylester (l-NAME), a competitive NOS inhibitor, or S-methylisothiourea hemisulfate (SMT), an iNOS inhibitor, was administered intraperitoneally for 13 consecutive days. The total number of terminal deoxynucleotidyl transferase-mediated biotinylated UTP nick end labeling-positive cells counted in the thalamus was found to be significantly decreased by chronic treatment of l-NAME or SMT, whereas neither the neuronal accumulation of ceroid-lipofuscin nor the microglial phagocytic activity was affected by these treatments. Moreover, the chronic treatment of l-NAME or SMT completely suppressed hemorrhage-necrotic changes in the small intestine of CD-/- mice, resulting in normal growth of the body weight of the mice. These results suggest that NO production via iNOS activity in microglia and peripheral macrophages contributes to secondary tissue damages such as neuronal apoptosis and intestinal necrosis, respectively.

New functional aspects of cathepsin D and cathepsin E.

Cathepsin D (CD) and cathepsin E are representative lysosomal and nonlysosomal aspartic proteinases, respectively, and play an important role in the degradation of proteins, the generation of bioactive proteins, antigen processing, etc. Recenty, several lines of evidence have suggested the involvement of these two enzymes in the execution of neuronal death pathways induced by aging, transient forebrain ischemia, and excessive stimulation of glutamate receptors with excitotoxins. CD has also been shown to mediate apoptosis induced by various stimuli and p53-dependent tumor suppression. To gain more insight into in vivo functions of CD, mice deficient in this enzyme were generated. The mutant animals showed a progressive atrophy of the intestinal mucosa, a massive destruction of lymphoid organs, and a profound accumulation of ceroid lipofuscin, and developed a phenotype resembling neuronal ceroid lipofucinosis, suggesting that CD is essential for proteolysis of proteins regulating cell growth and tissue homeostasis. It has also been shown that CD molecules secreted from human prostate carcinoma cells are responsible for the generation of angiostatin, a potent endogenous inhibitor of angiogenesis, suggesting its contribution to the prevention of tumor growth and angiogenesis-dependent growth of metastases. Interestingly, pro-CD from human breast carcinoma cells showed a significantly lower angiostatin-generating activity than that from prostate carcinoma cells. Since deglycosylated CD molecules from both carcinoma cells showed a low angiostatin-generating activity, this discrepancy appeared to be attributed to the difference in the carbohydrate structures of CD molecules between the two cell types and to contribute to their potency to prevent tumor growth and metastases.

Genetic defects and clinical characteristics of patients with a form of oculocutaneous albinism (Hermansky-Pudlak syndrome) [correction of (Hennansky-Pudlak)

<b>NEW ENGLAND JOURNAL OF MEDICINE</b> <b>Genetic Defects and Clinical Characteristics of Patients With a Form of Oculocutaneous Albinism (Hennansky-Pudlak Syndrome)</b> <i>William A. Gahl, M.D., Ph.D., Mark Brantly, M.D., Muriel I. Kaiser-Kupfer, M.D., Fumino Iwata, M.D., Senator Hazelwood, B.S., Vorasuk Shotelersuk, M.D., Lynn F. Duffy, M.D., Ernest M. Kuehl, James Troendle, Ph.D., and Isa Bernardini, M.Ed.</i> <i>Background</i>Hermansky–Pudlak syndrome is characterized by oculocutaneous albinism, a storage-pool deficiency, and lysosomal accumulation of ceroid lipofuscin, which causes pulmonary fibrosis and granulomatous colitis in some areas. All identified affected patients in northwest Puerto Rico are homozygous for a 16-bp duplication in exon 15 of a recently cloned gene,<i>HPS</i>. We compared the clinical and laboratory characteristics of these patients with those of patients without the 16-bp duplication. <i>Methods</i>Forty-nine patients—27 Puerto Ricans and 22 patients from the mainland United States who were not of Puerto Rican descent—were given a diagnosis on the basis of albinism and the absence of platelet dense bodies. We used the polymerase chain reaction to determine which patients carried the 16-bp duplication. <i>Results</i>Twenty-five of the Puerto Rican patients were homozygous for the 16-bp duplication, whereas none of the non–Puerto Rican patients carried this mutation. Like the patients without the duplication, the patients with the 16-bp duplication had a broad variation in pigmentation. Nine of 16 adults with the duplication, but none of the 10 without it, had a diffusing capacity for carbon monoxide that was less than 80 percent of the predicted value. High-resolution computed tomography in 12 patients with the 16-bp duplication revealed minimal fibrosis in 8, moderate fibrosis in 1, severe fibrosis in 1, and no fibrosis in 2. Computed tomography in eight patients without the duplication revealed minimal fibrosis in three and no fibrosis in the rest. Inflammatory bowel disease developed in eight patients (four in each group) between 3 and 25 years of age. <i>Conclusions</i>The 16-bp duplication in exon 15 of<i>HPS</i>, which we found only in Puerto Rican patients, is associated with a broad range of pigmentation and an increased risk of restrictive lung disease in adults. <i>1998;338:1258-1264.</i>

Hermansky-Pudlak Syndrome: Models for Intracellular Vesicle Formation

Hermansky-Pudlak syndrome (HPS) is an autosomal recessive disorder characterized by pigment dilution, nystagmus, decreased visual acuity, a bleeding diathesis, and lysosomal accumulation of ceroid lipofuscin. Electron microscopic evidence demonstrating lack of platelet-dense bodies provides thesine qua nonfor diagnosing HPS. Ceroid lipofuscinosis is considered to cause several serious complications, including progressive pulmonary fibrosis leading to death in the fourth or fifth decades. Currently, only symptomatic treatment can be offered. Although rare in the general population, HPS occurs in northwest Puerto Rico with a prevalence of 1 in 1800.HPS1,the first gene found to be responsible for HPS, was mapped to chromosome 10q23 and subsequently isolated and sequenced. It consists of 20 exons encoding a 700-amino acid, 79.3-kDa peptide with no homology to any known protein. All 10HPS1mutations reported to date, including the 16-bp duplication found in all northwest Puerto Rican patients, result in truncated proteins. The two mutations in the mousepale eargene (ep), which is the murine homology ofHPS1,cause similarly truncated proteins. The pathologic nature of these truncation mutations may result from unstable mRNA. However, in combination with the absence of any disease-causing missense mutations, it may indicate that the C-terminus of the HPS1 peptide is functionally important. The disorder HPS displays locus heterogeneity, consistent with the existence of 14 mouse strains manifesting both hypopigmentation and a platelet storage pool deficiency. Two mouse models,pearlandmocha,have mutations in the β3A and δ subunits of the adaptor-3 complex, respectively. This suggests that defective vesicular trafficking, specifically cargo packaging, vesicle formation, vesicle docking, or membrane fusion, may comprise the basic defect in HPS. Studies of the proteins involved in intercompartmental transport for melanosomes, platelet-dense bodies, and lysosomes should lead to a better understanding of the mechanisms of organellogenesis and to more effective therapies for HPS.

Clinical and biochemical findings in Puerto Ricans and Non-Puerto Ricans with Hermansky-Pudlak Syndrome (HPS) † 603

HPS consists of tyrosinase-positive albinism, a platelet storage pool defect, and lysosomal accumulation of ceroid lipofuscin, which can result in pulmonary fibrosis or granulomatous colitis. HPS occurs worldwide but primarily in NW Puerto Rico (PR). The common PR mutation is a 16 bp duplication in the HPS gene on 10q23, which produces a 79.3 kD protein of unknown function.

Neuronal ceroid lipofuscinosis with prominent accumulation of ceroid lipofuscin in the myocardium

Neuronal ceroid lipofuscinosis with prominent accumulation of ceroid lipofuscin in the myocardium

Protease inhibitors as a model for NCL disease, with special emphasis on the infantile and adult forms.

An animal model of NCL disease has been developed with the use of protease inhibitors. Young rats received a continuous infusion of various specific protease inhibitors or of physiological saline into the lateral ventricle of the brain using osmotic mini-pumps. Treatment lasted for 2 weeks, at which time animals were sacrificed and the brains were removed and processed for light or electron microscopic analysis. The thiol protease inhibitors leupeptin and E64C, but not saline or the serine protease inhibitor aprotinin, caused a massive accumulation of ceroid-lipofuscin (CL) in brain cells that bore a strong morphological resemblance to the CL in the infantile and adult forms of NCL disease, and bore similarity to the CL of the late infantile and juvenile forms. Leupeptin also caused the death of cerebellar Purkinje cells, as is seen in the infantile and adult forms of NCL. Further evidence is presented in support of the hypothesis (Ivy et al.: Science 226:985-987, 1984) that decreased or defective lysosomal thiol proteases or their substrates may underly the pathogenesis of at least the infantile and adult forms of NCL disease. Administration of protease inhibitors to the brains of young rats provides an important model for studying the cellular mechanisms of ceroid-lipofuscino-genesis.