Mitochondrial-encoded gene regulation in rat pancreatic islets.
Mitochondrial adenosine triphosphate (ATP) generation plays a major role in insulin secretion in pancreatic islet beta cells. The relationship between age and nutritional status of the islet and mitochondrial gene messenger RNA (mRNA) expression was investigated. Three animal groups were studied: infant (12-day-old) rats fed either mother's milk or a high carbohydrate (HC) diet; young (2 to 4-month-old) rats; and old (12 to 14-month-old) rats. The expression of mitochondrial cytochrome oxidase (CYO) (subunits I, II, and III), beta-nicotinamide adenine dinucleotide, reduced form dehydrogenase subunit 4 (NADH-DH4), and ATP synthase (subunit 6) (ATP-SYN6) mRNAs was characterized by semiquantitative reverse-transcriptase polymerase chain reaction (RT-PCR). The mitochondrial gene mRNAs were identified in each of the groups of rat islets and in RINm5F cells. CYO-II mRNA expression in young and old rat pancreatic islets was 12.7- and 8.2-fold higher, respectively, compared with the level in infant rat islets. The expression of NADH-DH4 and ATP-SYN6 mRNAs was 47% and 40% lower, respectively, in young rat islets compared with the level in infant rat islets. CYO-I, CYO-III, and cytoplasmic glyceraldehyde-3-phosphate dehydrogenase (GPDH) mRNA expression did not differ between experimental groups. Artificial rearing of infant rat pups on a HC diet for 8 days lead to a 3.3-fold increase in islet CYO-II mRNA expression compared with mother-fed pups. However, glucose (11 mmol/L) stimulation of cultured isolated islets from young and old rats for 4 days failed to affect the expression level of mitochondrial gene mRNAs. Thus, aging affected the differential expression of CYO-II, NADH-DH4, and ATP-SYN6 mRNAs in rat islets. CYO-II mRNA expression was modulated only in infant rat islets after in vivo administration of carbohydrate.
Lee
B
B
Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences,  State University of New York at Buffalo, 14214, USA.
Srinivasan
M
M
Aalinkeel
R
R
Patel
M S
MS
Laychock
S G
SG
D000375:Aging / Q000502:physiology; D000818:Animals; D000833:Animals, Suckling; D002478:Cells, Cultured; D004272:DNA, Mitochondrial / Q000235:genetics; D004040:Dietary Carbohydrates / Q000008:administration & dosage / Q000494:pharmacology; D003576:Electron Transport Complex IV / Q000235:genetics; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D005947:Glucose / Q000008:administration & dosage / Q000494:pharmacology; D007515:Islets of Langerhans / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D008297:Male; D008928:Mitochondria / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics*; D025261:Mitochondrial Proton-Translocating ATPases; D009245:NADH Dehydrogenase / Q000235:genetics; D010085:Oxidative Phosphorylation; D021122:Protein Subunits; D006180:Proton-Translocating ATPases / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction
D004272:DNA, Mitochondrial; D004040:Dietary Carbohydrates; D021122:Protein Subunits; D012333:RNA, Messenger; D009245:NADH Dehydrogenase; D003576:Electron Transport Complex IV; C412204:ATP synthase subunit 6; D025261:Mitochondrial Proton-Translocating ATPases; D006180:Proton-Translocating ATPases; D005947:Glucose