All Phenotypes Lamp2<tm1Amcu> MGI Mouse

decreased body weight ( J:215605 )

• mutant males exhibit a significantly lower body weight than control males up to 3.5 months of age

• however, this difference is not visible after 4 months of age

weight loss ( J:215605 )

• after 24 or 48 hr starvation, 4-month-old males display a greater % of body weight loss than control mice

increased susceptibility to weight gain ( J:215605 )

• despite a higher EE, mutant mice gain more weight on a HFD and show increased fat mass and liver and perigonadal WAT weight gains than control mice

enlarged liver ( J:215605 )

• mutant mice display enlarged livers

• after 16 weeks on a high-fat diet (HFD; 60% calories from fat), mutant mice exhibit significantly larger livers than control mice

increased liver weight ( J:215605 )

• mutant mice exhibit an increased liver weight relative to body weight

enhanced behavioral response to xenobiotic ( J:215605 )

• time for recovery of the righting reflex after zoxazolamine-induced paralysis is significantly increased relative to controls, indicating decreased liver function

decreased locomotor activity ( J:215605 )

• on a regular chow diet, mutant mice exhibit reduced physical activity relative to control mice

abnormal autophagy ( J:215605 )

• mice are unable to internalize and degrade select proteins by chaperone-mediated autophagy (CMA)

• in vivo blockage of lysosomal proteolysis by i.p. injection of leupeptin revealed that GAPDH (a known CMA substrate) is no longer degraded in mutant liver lysosomes

• in contrast, lysosomal delivery and degradation of cytosolic proteins such as cyclophillin (a non-CMA substrate) is normal

increased circulating alanine transaminase level ( J:215605 )

• serum ALT levels are significantly increased, indicating hepatocyte damage

• after 16 weeks on a HFD, mice exhibit significantly greater serum ALT levels than control mice

increased energy expenditure ( J:215605 )

• on a regular chow diet, mutant mice show significantly higher energy expenditure (EE) than control mice throughout a 24 hr cycle; however, no difference in food intake (meal number and size) is observed

• a HFD has a significantly smaller impact on lowering the EE in mutant mice relative to control mice

• after a 24 hr starvation, mutant mice exhibit a significantly higher EE than control mice during the day cycle

increased carbon dioxide production ( J:215605 )

• fed mutant mice exhibit higher average values of CO2 production than control mice

increased oxygen consumption ( J:215605 )

• fed mutant mice exhibit higher average values of O2 consumption than control mice

increased respiratory quotient ( J:215605 )

• on a regular chow diet, mutant mice exhibit higher respiratory exchange ratio (RER) values than control mice during the 24 hr cycle

• mutant RER values remain higher than in controls during the first 6 hr of a 24 hr starvation period

abnormal glucose homeostasis ( J:215605 )

• mutant livers exhibit higher lactate content and specific activity of glycolytic enzymes (GAPDH and PK), suggesting enhanced glycolysis

• in culture, primary hepatocytes from mutant mice show significantly higher basal glycolytic rates and maximal glycolytic capacity and higher levels of glycolytic enzymes relative to control hepatocytes; basal and maximal glycolytic capacity remains significantly higher than in controls even 24 hr after removal of serum from the culture media

• after a 24 hr starvation, levels of different glycolytic enzymes in mutant livers remain higher than in control livers

decreased fasting circulating glucose level ( J:215605 )

• after a 8 hr starvation (overnight fasting), mutant mice show a significant drop in blood glucose levels relative to control mice

• reduced blood glucose levels in response to short- and long-term fasting are noted even when mutant mice are fed a HFD

• lower blood glucose observed during starvation are not due to increased circulating insulin levels

improved glucose tolerance ( J:215605 )

• mutant mice display improved glucose tolerance even when placed on a HFD

• lower blood glucose observed during the glucose tolerance test are not due to increased circulating insulin levels

decreased liver glycogen level ( J:215605 )

• biochemical analysis and PAS staining revealed a significant reduction of glycogen content in mutant livers

decreased hepatic glucose production ( J:215605 )

• following injection of a pyruvate bolus (converted into glucose in liver), overnight fasted mutant mice show a significantly smaller increase in blood glucose than controls, suggesting reduced hepatic gluconeogenesis

abnormal lipid homeostasis ( J:215605 )

• mutant mice show a significant reduction in starvation-induced lysosomal degradation of liver enzymes related to lipid metabolism

• lysosomal degradation of some enzymes is also reduced even under fed conditions; accordingly, levels of many lipid metabolic enzymes are increased in mutant liver cytosolic fractions

• in culture, primary hepatocytes from mutant mice show increased content of enzymes involved in lipid metabolism and reduced lysosomal degradation of these enzymes

• although basal oxygen consumption rates are normal, mutant hepatocytes exhibit significantly reduced maximal mitochondrial respiratory capacity, fail to increase mitochondrial respiration in response to a lipogenic challenge and show lower rates of beta-oxidation in these conditions

• the VLDL secretion rate is significantly reduced in mutant livers

increased liver triglyceride level ( J:215605 )

• after two i.p. injections of isoproterenol to induce peripheral lipolysis, mutant livers show a ~5-fold increase in TG content relative to control livers

abnormal enzyme/coenzyme activity ( J:215605 )

• mutant mice exhibit lower basal levels of glycogen synthetase (GS)

• a higher percentage of GS is in an inactive phosphorylated state (pGS)

• however, GS is still efficiently activated, even at higher levels than in control mice, following stimulation of hepatic glycogenesis by insulin injection in overnight starved mice

enlarged liver ( J:215605 )

• mutant mice display enlarged livers

• after 16 weeks on a high-fat diet (HFD; 60% calories from fat), mutant mice exhibit significantly larger livers than control mice

increased liver weight ( J:215605 )

• mutant mice exhibit an increased liver weight relative to body weight

decreased liver glycogen level ( J:215605 )

• biochemical analysis and PAS staining revealed a significant reduction of glycogen content in mutant livers

increased liver triglyceride level ( J:215605 )

• after two i.p. injections of isoproterenol to induce peripheral lipolysis, mutant livers show a ~5-fold increase in TG content relative to control livers

hepatic steatosis ( J:215605 )

• mutant hepatocytes contain an increased number and size of cytosolic lipid droplets (LDs), which become even more evident after starvation

• in the fed state, the major lipid species that accumulate in mutant livers are cholesterol esther and triacylglycerides (TG)

• after 24 hr of starvation, mutant livers also accumulate TG precursors, such as free fatty acids (FFAs) and diacylglycerol (DAG)

• after two i.p. injections of isoproterenol to induce peripheral lipolysis, mutant livers display more pronounced LD accumulation than control livers, with a ~5-fold increase in TG content, whereas cholesterol content remains unchanged

• after 16 weeks on a HFD, mutant livers exhibit more pronounced LD accumulation than control livers

pale liver ( J:215605 )

• mutant mice display discolored livers

• after 16 weeks on a HFD, mutant mice exhibit significantly paler livers than control mice

abnormal liver physiology ( J:215605 )

• mutant livers exhibit a switch from carbohydrate synthesis and storage to carbohydrate hydrolysis and utilization

increased hepatocyte apoptosis ( J:215605 )

• liver apoptosis is significantly increased, as shown by TUNEL analysis

decreased liver function ( J:215605 )

• significant decline in liver function as early as 4 months of age, as shown by the increased clearance time of zoxazolamine (a muscle relaxant metabolized by the liver), in a zoxazolamine-induced paralysis time assay

decreased brown fat cell lipid droplet size ( J:215605 )

• after a 24 hr starvation, mutant mice show smaller adipocyte LDs in interscapular brown adipose tissue (BAT) than control mice

decreased white fat cell lipid droplet size ( J:215605 )

• after a 24 hr starvation, mutant mice show smaller adipocyte LDs in perigonadal WAT than control mice

decreased gonadal fat pad weight ( J:215605 )

• after a 24 hr starvation, mutant mice show reduced perigonadal white adipose tissue (WAT) weight than control mice

decreased percent body fat/body weight ( J:215605 )

• fed mutants exhibit lower total-body fat mass (as a percent of body weight) than control mice; this is further accentuated after a 24 hr starvation

cellular phenotype ( J:215605 )

N

• liver lysosomes show no differences in their content of mature hydrolases (e.g. cathepsin D), enzymatic activities (e.g. total liver and lysosomal beta-hexosaminidase activities), or stability of their membranes relative to control lysosomes

• steady state levels of integral autophagosome components and autophagy receptors are normal in mutant livers

• most autophagic vacuoles in mutant livers are autophagolysosomes, and the autophagosome/autophagolysosome ratio is similar to that in control mice