Development of a new model system to dissect isoform specific Akt signalling in adipocytes

Kajno, Esi; McGraw, Timothy E.; González, Eva

doi:10.1042/bj20150191

Cited by 29 publications

(34 citation statements)

References 45 publications

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“…It is also conceivable that a permissive amount of insulin signaling may be sufficient for the full biological effects of insulin. This concept is supported by literature showing a lack of linearity between insulin signaling and insulin effects on glucose transport (Gonzalez et al, 2011; Kajno et al, 2015; Tan et al, 2015) and other biological processes (Guilherme et al, 2017; Kajno et al, 2015). Consistent with this, we observe impaired insulin-stimulated Akt T308 phosphorylation in WAT of HFD-fed AdChREBP KO vs. ChREBP fl/fl mice (Fig 4N, grey vs. black bars) without impairments in insulin-stimulated glucose transport in adipocytes isolated from HFD-fed AdChREBP KO mice (Fig S5D, white vs. black bars).…”

Section: Discussionmentioning

confidence: 58%

Absence of Carbohydrate Response Element Binding Protein in Adipocytes Causes Systemic Insulin Resistance and Impairs Glucose Transport

et al. 2017

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Summary Lower adipose-ChREBP and de novo lipogenesis (DNL) are associated with insulin resistance in humans. Here we generated adipose-specific ChREBP knockout (AdChREBP KO) mice with negligible sucrose-induced DNL in adipose tissue (AT). Chow-fed AdChREBP KO mice are insulin-resistant with impaired insulin action in liver, muscle and AT, and increased AT inflammation. HFD-fed AdChREBP KO mice are also more insulin-resistant than controls. Surprisingly, adipocytes lacking ChREBP display a cell-autonomous reduction in insulin-stimulated glucose transport which is mediated by impaired Glut4 translocation and exocytosis, not lower Glut4 levels.. AdChREBP KO mice have lower levels of palmitic acid esters of hydroxy stearic acids (PAHSAs) in serum and AT. 9-PAHSA supplementation completely rescues their insulin resistance and AT inflammation. 9-PAHSA also normalizes impaired glucose transport and Glut4 exocytosis in ChREBP KO adipocytes. Thus, loss of adipose-ChREBP is sufficient to cause insulin resistance potentially by regulating AT glucose transport and flux through specific lipogenic pathways.

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Section: Discussionmentioning

confidence: 58%

Absence of Carbohydrate Response Element Binding Protein in Adipocytes Causes Systemic Insulin Resistance and Impairs Glucose Transport

et al. 2017

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“…For example, the AKT2 isoform is most abundant in metabolic tissues, and its deletion in mice causes an insulin resistance-like phenotype (159), whereas the deletion of AKT1 does not cause metabolic defects but is required for cell growth (160). Gonzalez and colleagues (161) used an elegant chemical genetic system to investigate isoform-specific AKT signaling by generating genetic mutants of AKT that are resistant to the potent allosteric AKT inhibitor MK-2206, pointing to overlapping and distinct functions. Using phosphoproteomics to study lung fibroblasts engineered to selectively express each of the three AKT isoforms, Sanidas et al (162) also investigated isoform-directed signaling.…”

Section: Biochemical Strategies For Studying Signaling Network Architmentioning

confidence: 99%

Illuminating the dark phosphoproteome

et al. 2019

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Protein phosphorylation is a major regulator of protein function and biological outcomes. This was first recognized through functional biochemical experiments, and in the past decade, major technological advances in mass spectrometry have enabled the study of protein phosphorylation on a global scale. This rapidly growing field of phosphoproteomics has revealed that more than 100,000 distinct phosphorylation events occur in human cells, which likely affect the function of every protein. Phosphoproteomics has improved the understanding of the function of even the most well-characterized protein kinases by revealing new downstream substrates and biology. However, current biochemical and bioinformatic approaches have only identified kinases for less than 5% of the phosphoproteome, and functional assignments of phosphosites are almost negligible. Notably, our understanding of the relationship between kinases and their substrates follows a power law distribution, with almost 90% of phosphorylation sites currently assigned to the top 20% of kinases. In addition, more than 150 kinases do not have a single known substrate. Despite a small group of kinases dominating biomedical research, the number of substrates assigned to a kinase does not correlate with disease relevance as determined by pathogenic human mutation prevalence and mouse model phenotypes. Improving our understanding of the substrates targeted by all kinases and functionally annotating the phosphoproteome will be broadly beneficial. Advances in phosphoproteomics technologies, combined with functional screening approaches, should make it feasible to illuminate the connectivity and functionality of the entire phosphoproteome, providing enormous opportunities for discovering new biology, therapeutic targets, and possibly diagnostics.

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“…Primers and vectors are listed in Supplementary Table S3. Plasmid pLVX-IRES-tdTomato-FlagAkt1 was a gift from Eva Gonzalez (Addgene plasmid # 64831) (Kajno et al, 2015) and plasmid p3xHA-C1 (Müller et al, 2012). The accuracy of DNA constructs was verified by sequencing.…”

Section: Dna Constructsmentioning

confidence: 99%

Thymosin β4 Regulates Focal Adhesion Formation in Human Melanoma Cells and Affects Their Migration and Invasion

Makowiecka

Małek

Mazurkiewicz

et al. 2019

Front. Cell Dev. Biol.

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Thymosin β4 (Tβ4), a multifunctional 44-amino acid polypeptide and a member of actin-binding proteins (ABPs), plays an important role in developmental processes and wound healing. In recent years an increasing number of data has been published suggesting Tβ4's involvement in tumorigenesis. However, Tβ4's role in melanoma tumor development still remains to be elucidated. In our study we demonstrate that Tβ4 is crucial for melanoma adhesion and invasion. For the purpose of our research we tested melanoma cell lines differing in invasive potential. Moreover, we applied shRNAs to silence TMSB4X (gene encoding Tβ4) expression in a cell line with high TMSB4X expression. We found out that Tβ4 is not only a component of focal adhesions (FAs) and interacts with several FAs components but also regulates FAs formation. We demonstrate that Tβ4 level has an impact on FAs' number and morphology. Moreover, manipulation with TMSB4X expression resulted in changes in cells' motility on non-coated and Matrigel TM (resembling basement membrane composition)-coated surfaces and drastically decreased invasion abilities of the cells. Additionally, a correlation between Tβ4 expression level and exhibition of mesenchymal-like [epithelialmesenchymal transition (EMT)] features was discovered. Cells with lowered TMSB4X expression were less EMT-progressed than control cells. Summarizing, obtained results show that Tβ4 by regulating melanoma cells' adhesion has an impact on motility features and EMT. Our study not only contributes to a better understanding of the processes underlying melanoma cells' capacity to create metastases but also highlights Tβ4 as a potential target for melanoma management therapy.

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Development of a new model system to dissect isoform specific Akt signalling in adipocytes

Abstract: Our study describes the development and validation of a new model system that allows for acute control of signalling by specific Akt isoforms. This model system revealed new insights into the role of Akt kinases in glucose transport and adipogenesis.

Cited by 29 publications

References 45 publications

Absence of Carbohydrate Response Element Binding Protein in Adipocytes Causes Systemic Insulin Resistance and Impairs Glucose Transport

Absence of Carbohydrate Response Element Binding Protein in Adipocytes Causes Systemic Insulin Resistance and Impairs Glucose Transport

Illuminating the dark phosphoproteome

Thymosin β4 Regulates Focal Adhesion Formation in Human Melanoma Cells and Affects Their Migration and Invasion

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