Early changes in gene expression in two models of Batten disease

Abstract

Infantile and juvenile neuronal ceroid lipofuscinosis (NCLs) are progressive neurodegenerative disorders of childhood with distinct ages of clinical onset, but with a similar pathological outcome. Infantile and juvenile NCL are inherited in an autosomal recessive manner due to mutations in the CLN1 and CLN3 genes, respectively. Recently developed Cln1-and Cln3-knockout mouse models share similarities in pathology with the respective human disease. Using oligonucleotide arrays we identi¢ed reproducible changes in gene expression in the brains of both 10-week-old Cln1-and Cln3-knockout mice as compared to wild-type controls, and con¢rmed changes in levels of several of the cognate proteins by immunoblotting. Despite the similarities in pathology, the two mutations a¡ect the expression of di¡erent, non-overlapping sets of genes. The possible signi¢cance of these changes and the pathological mechanisms underlying NCL diseases are discussed. ß

Alterations in striatal dopamine catabolism precede loss of substantia nigra neurons in a mouse model of juvenile neuronal ceroid lipofuscinosis

“…Degradation of norepinephrine requires two additional enzymes, aldehyde reductase and aldehyde dehydrogenase (Fig 1B). Mining of several published microarray data sets performed on the Cln3 -/-mice showed a selective downregulation in the expression of Comt but none of the other enzymes involved in catecholamine catabolism were altered (Fig 1A & 1B) Elshatory et al, 2003). Normal synthesis of catecholamines is achieved through conversion of tyrosine to DOPA, dopamine, norepinephrine, and epinephrine, sequentially.…”

“…The Cln3 -/-mouse model for Batten disease has a substantial decrease in the levels of catechol-O-methyl transferase (Comt) mRNA in the brain (Elshatory et al, 2003). This enzyme, along with monoamine oxidase, MAO, facilitates the degradation of dopamine both within the striatum and other portions of the nervous system ( Fig 1A).…”

“…Protein concentration was determined on aliquots from each of the tissue homogenates using a Lowry protein assay (BioRad Inc., Hercules, CA). SDS PAGE (10-13%) and immunoblotting was performed using standard techniques (as outlined in Elshatory, et al, 2003). Antibodies used for immunoblotting included anti-β-Actin (Sigma, St. Louis MO), anti-COMT (Transduction Labs, Lexington, KY), anti-DAT, anti-D1α (Chemicon, Temecula, CA), and anti-MAO-B (Santa Cruz Biotechnologies, Santa Cruz, CA).…”

“…The mean co-efficient of error (CE) for all individual optical fractionator and nucleator estimates was calculated according to the method of Gundersen and Jensen and was less than 0.08 in all these analyses (Gundersen and Jensen, 1987). Evaluation of several published microarray data sets performed on the Cln3 -/-mice showed a selective down regulation in the expression of Comt (3.56 fold decrease, 10-week whole brain microarray) with a sparing of all other enzymes involved in catecholamine catabolism (Dopamine, A & Norepinephrine, B) Elshatory et al, 2003). Synthesis of catecholamine is achieved through conversion of tyrosine to DOPA, followed by the subsequent selective conversion to dopamine, norepinephrine, and epinephrine.…”

“…Interestingly, in the Cln3 -/-mice, as well as other NCL models, there is a marked increase in the levels of both reactive astrocytes and microglia within this compartment, indicative of cellular damage (Pontikis et al, 2004;Pontikis et al, 2005;Kielar et al, 2007). Interestingly, gene expression studies of the Cln3 -/-mouse brain have uncovered a marked decrease in the expression of catechol-O-methyl transferase (COMT) (Elshatory et al, 2003). This is a key enzyme involved in the degradation of catecholamines within the striatum, as well as other brain regions, calling into question the integrity of the metabolism and function of this neurotransmitter family in the Cln3 -/-mouse.…”