Deficiency of the RIIβ subunit of PKA affects locomotor activity and energy homeostasis in distinct neuronal populations

Abstract

Targeted disruption of RIIβ-protein kinase A (PKA) in mice leads to a lean phenotype, increased nocturnal locomotor activity, and activation of brown adipose tissue. Because RIIβ is abundantly expressed in both white and brown adipose tissue as well as the brain, the contribution of neuronal vs. peripheral PKA to these phenotypes was investigated. We used a Cre-Lox strategy to reexpress RIIβ in a tissue-specific manner in either adipocytes or neurons. Mice with adipocyte-specific RIIβ reexpression remained hyperactive and lean, but pan-neuronal RIIβ reexpression reversed both phenotypes. Selective RIIβ reexpression in all striatal medium spiny neurons with Darpp32-Cre corrected the hyperlocomotor phenotype, but the mice remained lean. Further analysis revealed that RIIβ reexpression in D2 dopamine receptor-expressing medium spiny neurons corrected the hyperlocomotor phenotype, which demonstrated that the lean phenotype in RIIβ-PKA-deficient mice does not develop because of increased locomotor activity. To identify the neurons responsible for the lean phenotype, we used specific Cre-driver mice to reexpress RIIβ in agouti-related peptide (AgRP)-, proopiomelanocortin (POMC)-, single-minded 1 (Sim1)-, or steroidogenic factor 1 (SF1)-expressing neurons in the hypothalamus, but observed no rescue of the lean phenotype. However, when RIIβ was reexpressed in multiple regions of the hypothalamus and striatum driven by Rip2-Cre, or specifically in GABAergic neurons driven by Vgat-ires-Cre, both the hyperactive and lean phenotypes were completely corrected. Bilateral injection of adeno-associated virus1 (AAV1)-Cre directly into the hypothalamus caused reexpression of RIIβ and partially reversed the lean phenotype. These data demonstrate that RIIβ-PKA deficiency in a subset of hypothalamic GABAergic neurons leads to the lean phenotype.mouse genetics | obesity | exercise | cAMP W e reported previously that mice lacking the protein kinase A (PKA) regulatory subunit RΙΙβ (RΙΙβ KO) exhibit a 50% reduction in white adipose tissue (WAT) and are resistant to dietinduced obesity (DIO) and diabetes (1, 2). These mice have an extended lifespan and show diminished age-related metabolic dysfunctions such as fatty liver and insulin resistance (3). Compared with their WT littermates, RIIβ KO mice have normal to slightly increased food intake, a twofold increase in nocturnal physical activity, and a basal metabolic rate (VO 2 consumption) that is higher than WT if calculated based on total body weight (4-6). RIIβ is highly expressed in the mouse CNS, brown adipose tissue (BAT), and WAT with limited expression elsewhere (1, 7-9). At the molecular level, RIIβ deficiency is accompanied by a compensatory increase in the PKA regulatory subunit RIα, which results in increased basal PKA activity and decreased total C subunit activity in brain, BAT, and WAT (1). These changes in PKA subunit composition may also alter PKA holoenzyme localization to specific signaling complexes because RIIβ has a much higher affinity for anchoring proteins (AKAPs)...

α-MSH and Foxc2 promote fatty acid oxidation through C/EBPβ negative transcription in mice adipose tissue

“…MCRs belong to the G-protein-couple receptor family; they are all linked to cAMP generation via stimulating G-proteins and adenylate cyclase1948. And their down-stream PKA activation could stimulate the activity of CPT-14950. Our results showed α-MSH and Foxc2 increased cAMP level and activated PKA signal.…”

Disruption of Type 3 Adenylyl Cyclase Expression in the Hypothalamus Leads to Obesity

“…According to previous report [16], four-site injections of 0.5 μL per site were performed for each side at the coordinates x = ± 0.5, y = −1.4, and z = −5.6 and −5.0, which corresponds to ventral and dorsal hypothalamus, respectively. For the VMH injection, two-site injections were performed for each side at the coordinates x = ± 0.5, y = −1.4, and z = −5.6.…”

Adolescent and adult rat cortical protein kinase A display divergent responses to acute ethanol exposure

“…Bands were visualized using enhanced chemiluminescence (ECL GE Healthcare, Amersham, UK) under nonsaturating conditions. PKA RIIα and RIIβ antibodies have previously been shown to have specificity based on immunoblot analysis conducted with RII knockout tissue (Carlson et al, 2013; Schillace et al, 2005; Zheng et al, 2013). Blots were then exposed to a β-actin specific antibody (Millipore, Billerica, MA) for normalization.…”