Kendrick A. Goss

Human iPSC models of neuronal ceroid lipofuscinosis capture distinct effects of TPP1 and CLN3 mutations on the endocytic pathway

Neuronal ceroid lipofuscinosis (NCL) comprises ∼13 genetically distinct lysosomal disorders primarily affecting the central nervous system. Here we report successful reprograming of patient fibroblasts into induced pluripotent stem cells (iPSCs) for the two most common NCL subtypes: classic late-infantile NCL, caused by TPP1(CLN2) mutation, and juvenile NCL, caused by CLN3 mutation. CLN2/TPP1- and CLN3-iPSCs displayed overlapping but distinct biochemical and morphological abnormalities within the endosomal-lysosomal system. In neuronal derivatives, further abnormalities were observed in mitochondria, Golgi and endoplasmic reticulum. While lysosomal storage was undetectable in iPSCs, progressive disease subtype-specific storage material was evident upon neural differentiation and was rescued by reintroducing the non-mutated NCL proteins. In proof-of-concept studies, we further documented differential effects of potential small molecule TPP1 activity inducers. Fenofibrate and gemfibrozil, previously reported to induce TPP1 activity in control cells, failed to increase TPP1 activity in patient iPSC-derived neural progenitor cells. Conversely, nonsense suppression by PTC124 resulted in both an increase of TPP1 activity and attenuation of neuropathology in patient iPSC-derived neural progenitor cells. This study therefore documents the high value of this powerful new set of tools for improved drug screening and for investigating early mechanisms driving NCL pathogenesis.

Fatty acid ethyl ester synthesis in the preparation of scotch whiskey

Fatty acid ethyl esters (FAEE), nonoxidative ethanol metabolites present in human organs commonly damaged by ethanol abuse, have been implicated as mediators of organ damage. FAEE are additives in various foods and beverages to provide flavor or fragrance, and therefore are common dietary lipid constituents. We hypothesized that FAEE could be generated during alcoholic beverage production because fatty acids are present within microorganisms and ethanol is generated during the fermentation process. In this report, we demonstrate that FAEE are present in commercially available scotch beverages, and that in the preparation of scotch, FAEE can be produced during the fermentation reaction as a result of FAEE synthase activity in the yeast. Following ingestion of scotch, preformed FAEE are delivered to GI tract. The consequences of ingestion of FAEE in scotch, if any, remain to be determined.

Novel LIPA mutations in Mexican siblings with lysosomal acid lipase deficiency

Lysosomal acid lipase (LAL) deficiency is an under-recognized lysosomal disease caused by deficient enzymatic activity of LAL. In this report we describe two affected female Mexican siblings with early hepatic complications. At two months of age, the first sibling presented with alternating episodes of diarrhea and constipation, and later with hepatomegaly, elevated transaminases, high levels of total and low-density lipoprotein cholesterol, and low levels of high-density lipoprotein. Portal hypertension and grade 2 esophageal varices were detected at four years of age. The second sibling presented with hepatomegaly, elevated transaminases and mildly elevated low-density lipoprotein and low high-density lipoprotein at six months of age. LAL activity was deficient in both patients. Sequencing of LIPA revealed two previously unreported heterozygous mutations in exon 4: c.253C>A and c.294C>G. These cases highlight the clinical continuum between the so-called Wolman disease and cholesteryl ester storage disease, and underscore that LAL deficiency represents a single disease with a degree of clinical heterogeneity.