In the journal Aging, a report has just been published describing the control of expression of SIRT1 by microRNAs. See Lee and Kemper (2010).
Three microRNAs implicated in their study are MIRN34A, MIRN132 and MIRN199A. To add to the conversation, I provide some other details of these microRNAs:
MIRN34A - expression in subcutaneous fat is correlated positively with BMI (Ortega, et al. 2010 PLoS ONE 5: e9022); the pre-adipocyte from an obese individual has 1.23-fold higher expression than from a lean person (Ortega, et al.); furthermore, the gene is upregulated during adipocyte differentiation (Ortega, et al.); lastly, confluent fibroblasts show 4.1-fold higher expression than sub-confluent cells (Hwang, et al. 2009 PNAS 106: 7016-7021)
MIRN132 - no other data to offer
MIRN199A - similarly, expression in subcutaneous fat is correlated positively with BMI (Ortega, et al. 2010 PLoS ONE 5: e9022); there is 2.3 to 3-fold higher expression in confluent fibroblasts than in sub-confluent cells (Hwang, et al.)
The two genes above, those with data, are certainly interesting and strengthen the metabolic links involving SIRT1.