Mechanisms by which autosomal recessive
mutations in <i>Lmna</i> cause familial
partial lipodystrophy type 2 (FPLD2) are poorly understood. To investigate
function of lamin A/C in adipose tissues, we created mice with an
adipocyte-specific loss of <i>Lmna</i> (<i>Lmna</i><sup>ADKO</sup>). Although <i>Lmna</i><sup>ADKO</sup> mice develop and
maintain adipose tissues in early postnatal life, they show a striking and
progressive loss of white and brown adipose tissues as they approach sexual
maturity. <i>Lmna</i><sup>ADKO</sup> mice exhibit
a surprisingly mild metabolic dysfunction on a chow diet, but on a high fat
diet they share many characteristics of FPLD2 including hyperglycemia, hepatic
steatosis, hyperinsulinemia, and almost undetectable circulating adiponectin
and leptin. Whereas <i>Lmna</i><sup>ADKO</sup>
mice have reduced regulated and
constitutive bone marrow adipose tissue with a concomitant increase in cortical
bone, FPLD2 patients have reduced bone mass and bone mineral density compared to
controls. In cell culture models of <i>Lmna</i>
deficiency, mesenchymal
precursors undergo adipogenesis
without impairment, whereas fully-differentiated adipocytes have increased
lipolytic responses to adrenergic stimuli. <i>Lmna</i><sup>ADKO</sup> mice faithfully reproduce many characteristics of
FPLD2 and thus provide a unique animal model to investigate mechanisms
underlying <i>Lmna</i>-dependent loss of
adipose tissues.