KSR2 is an essential regulator of AMP kinase, energy expenditure, and insulin sensitivity
Authors: Eun-Gyoung Hong
Diane L Costanzo-Garvey
Amy L Swift
Denise Chen
Jeffery L Stock
Matthias H Tschöp
Mike Winer
Deborah K Morrison
Robert E Lewis
Tina Treece
Aimee Schreiner
Min Wu
Paul T Pfluger
Mario R Fernandez
Jason K Kim
Robert L Kortum
John McNeish
Oleg Chaika
Matthew Boehm
Deanna J Volle
Kurt Fisher
John Y Jun
Andrey S Shaw
Hwi Jin Ko
Lisa R Leon
Michele K Dougherty
Journal: Cell Metabolism (2009)
Discipline: MOLECULAR BIOLOGY & GENETICS
Keywords: KSR2; AMPK; energy metabolism; glucose uptake; fatty acid oxidation
Affiliations: Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, NE 68198-7696, USA.

Abstract:  Kinase suppressors of Ras 1 and 2 (KSR1 and KSR2) function as molecular scaffolds to potently regulate the MAP kinases ERK1/2 and affect multiple cell fates. Here we show that KSR2 interacts with and modulates the activity of AMPK. KSR2 regulates AMPK-dependent glucose uptake and fatty acid oxidation in mouse embryonic fibroblasts and glycolysis in a neuronal cell line. Disruption of KSR2 in vivo impairs AMPK-regulated processes affecting fatty acid oxidation and thermogenesis to cause obesity. Despite their increased adiposity, ksr2(-/-) mice are hypophagic and hyperactive but expend less energy than wild-type mice. In addition, hyperinsulinemic-euglycemic clamp studies reveal that ksr2(-/-) mice are profoundly insulin resistant. The expression of genes mediating oxidative phosphorylation is also downregulated in the adipose tissue of ksr2(-/-) mice. These data demonstrate that ksr2(-/-) mice are highly efficient in conserving energy, revealing a novel role for KSR2 in AMPK-mediated regulation of energy metabolism. 

Retracted: No

PubPeer comments:
 Curious about issues in Figs 6C-6E. Insulin clamp data is not well reported and may not support conclusion and part of title of this paper. Easy stuff. What are right units? Different in 6C vs D E. Likely umol kg min. Where are methods for this experiment? I can t find anything. NOTHING, unless I completely missed it in main text and supplemental info. Literally, nothing, not mentioned. Where are insulin levels during clamp? Almost impossible to evaluate this experiment without. Mutant mice are hyperinsulinemic. Supplementary table showing another clamp in different mice indicates insulin infused at 2.5 mU kg min (low dose). Is it same here? Was there a rise in basal to clamp insulin? ![file] Figure legends says mean + - SD. But methods says all figures mean + - SE. Which is it? ![file] , 
 Are the original pictures available? The published pictures show black bars in the web and pdf version. ![file] ![file] , 
 #1 Thanks for pointing this out. Sorry that this wasn t brought to my attention until yesterday. Regarding the clamp experiments, I contacted Jason Kim (U. Mass Medical) who provided the following: It looks like Fig. 6C unit did not correctly convert to symbol to read (u00b5mol kg min), and it should be the same unit as Fig. 6D E. It does not look like we measured insulin levels from these mice. It was a standard insulin clamp using 2.5 mU kg min insulin infusion rate, and the methods can be referenced as attached. The data should be mean + - SE. Jason provided a chapter he wrote as reference (Hyperinsulinemicu2013Euglycemic Clamp to Assess Insulin Sensitivity In Vivo, Chapter 15 in C. Stocker (ed.), Type 2 Diabetes, Methods in Molecular Biology, vol. 560 DOI 10.1007 978-1-59745-448-3_15). I hope this clarifies the issue. #2 Regarding the panels, I m not quite sure what it being asked. I can see the data clearly. The black lines are only provided to delineate the separate blots and do not obscure the interpretation. To be honest, I m not sure I can find the blots in the upper panel since the work was done more that 11 years ago. Those were done in my lab and they have been confirmed in other papers by others in the lab (e.g., Fisher et al. MCB 2015). The bottom panel are blots performed in Debbie Morrison s lab (NCI) and I would stake my life on Debbie s research. Her lab s work is impeccable. For me, one of the beautiful things about this paper is that we had the basic findings confirmed and expanded by multiple wonderful collaborators, especially Matthias Tschu00f6p and Paul Pfluger, plus Debbie and Jason. In one respect, the extensive author list diminished the exceptional effort of Diane Costanzo-Garvey, and Aimee Schreiner, who made the original discovery and that of Paul who performed the metabolic analysis, but it gave us great confidence that we were describing both the phenotype and a critical KSR2-modulated mechanism accurately. , 
 #3 Unfortunately, many commenters in this forum do not adequately describe their points using words. I believe #2 was pointing out that some bands appear to be highly pixelated (so that they appear to be composed of  black bars ). At least in some cases, this is a problem only with some sources of the image. For all Figures, the HTML sources at the journal include two-different resolution versions: a  full-size image and a  high-res image . The latter is the best quality. For Figure 1E (the lower of the two examples in post #2), the pixelations apparent in post #2 are only apparent in the lower-quality HTML image, and not in the better quality HTML image or in the PDF. For Figure 2D (the upper of the two examples in post #2), the resolution is poor even in the better quality image, but these are relatively common types of image degradation artifacts that are not otherwise noteworthy. ,