2011 ADA Posters 1261-2041.indd - Diabetes

Integrated Physiology/
Obesity
POSTERS
In this study, we identify the histone demethylase plant homeodomain
(PHD) fi nger 2 (phf2) as an important regulator of both glycolytic and lipogenic
gene expression acting as an upstream regulator of ChREBP activity. In
cultured mouse hepatocytes, using chromatin immunoprecipitation (ChIP)
analysis, we show that phf2 is recruited to the ChoRE containing region
of both glycolytic and lipogenic gene promoters (including LPK and FAS)
in response to glucose and insulin stimulation. Then, phf2 specifi cally
demethylates di-methylated lysine 9 on histone H3 (H3K9Me2) allowing the
recruitment of ChREBP to these promoters to increase fatty acid synthesis.
In the opposite, phf2 silencing results in increased H3K9Me2 methylation at
these promoters, resulting in decreased of ChREBP occupancy and inhibition
of fatty acid synthesis. Finally, in liver of fed diabetic db/db mice, high phf2
activity at these glycolytic and lipogenic gene promoters is associated with
decreased H3K9Me2 methylation and increased ChREBP transcriptional
activity, correlating with the development of hepatic steatosis. Our fi ndings
suggest that inhibition of phf2 activity in liver may be benefi cial for treating
hepatic steatosis in state of obesity and type 2 diabetes.
Supported by: Agence Nationale de la recherhe (ANR-09-JCJC-0057-01) and by
the FRM
1692-P
Prenatal Protein Defi ciency Alters Circadian Rhythms in Core Clock
Oscillator Protein Expression in the Offspring
ARMAND V. CENTANNI, DIANA C. ALBARADO, GREGORY M. SUTTON, Baton
Rouge, LA
The mechanisms linking intrauterine growth retardation (IUGR) with
adulthood obesity and diabetes are unknown. Previous studies performed
in our lab have demonstrated an altered circadian phenotype in 8 wk old
male C57Bl/6J mice subjected to protein malnutrition (undernourished
offspring, UO) in utero coupled with altered glucose homeostasis. Gene
expression of the nuclear receptor, Rev-erbα, a component of the circadian
clock mechanism in liver was dramatically reduced and out of phase in UO at
8 wk of age compared to control offspring (CO). Rev-erbα repressed genes
involved in circadian regulation (Bmal1 and Per2) were increased in UO mice.
Surprisingly, protein expression of Rev-erbα in UO liver did not oscillate and
was expressed at similar levels at circadian time points (CT) 1200 and 2400
(noon and midnight) suggesting gene expression and protein translation are
misaligned compared to CO. Phosphorylation of glycogen synthase kinase-
3β and protein kinase B, two second messenger signaling molecules that
play a role both directly (GSK3β) and indirectly (PKB) in Rev-erbα regulation.
We now demonstrate that phosphorylation at the GSKβ site on Rev-erbα
is dramatically reduced in UO liver, suggesting altered transcription and
regulation. These data suggest potentially cell surface signaling, perhaps
through insulin may play a role in impaired clock controlled processes in
UO mice. We conclude that UO mice exhibit a metabolic disorder involving
abnormal circadian patterns of gene and protein expression. Altered Reverbα
expression and function may be a key factor in metabolic dysregulation
associated with IUGR. ADA-Funded Research
1693-P
Pyruvate Carboxylase, a Novel Therapeutic Target for Type 2 Diabetes
NAOKI KUMASHIRO, SARA A. BEDDOW, IOANA FAT, SACHIN K. MAJUMDAR,
FITSUM GUEBRE-EGZIABHER, JENNIFER L. CHRISTIANSON, PRASAD MANCHEM,
BRETT P. MONIA, SANJAY BHANOT, GERALD I. SHULMAN, VARMAN T. SAMUEL,
New Haven, CT, Carlsbad, CA
Fasting hyperglycemia in T2D is due to increased gluconeogenesis, a
process for which the enzymatic regulation is poorly understood. We recently
observed an association between fasting hyperglycemia and expression
of pyruvate carboxylase (PC) but not PEPCK and G6Pase in several rodent
models and thus, hypothesized that PC is an excellent therapeutic target for
T2D. To test this, we used antisense oligonucleotides (ASO’s) to decrease
PC expression in normal SD rats fed a regular chow, high-fat fed (HFF) SD
rats and Zucker Diabetic Fatty (ZDF) rats. ASO’s specifi cally decrease target
expression in liver and adipose but not other tissues (e.g. pancreas). PC ASO
treatment decreased PC expression by ∼90%. In regular chow fed rats, this
reduced plasma glucose concentrations in both the fasted [Cont: 109±1 vs.
PC: 103±1, (P