TY  - JOUR
A1  - Fedders, Ronja
A1  - Muenzner, Matthias
A1  - Weber, Pamela
A1  - Sommerfeld, Manuela
A1  - Knauer, Miriam
A1  - Kedziora, Sarah
A1  - Kast, Naomi
A1  - Heidenreich, Steffi
A1  - Raila, Jens
A1  - Weger, Stefan
A1  - Henze, Andrea
A1  - Schupp, Michael
T1  - Liver-secreted RBP4 does not impair glucose homeostasis in mice
JF  - The journal of biological chemistry
N2  - Retinol-binding protein 4 (RBP4) is the major transport protein for retinol in blood. Recent evidence from genetic mouse models shows that circulating RBP4 derives exclusively from hepatocytes. Because RBP4 is elevated in obesity and associates with the development of glucose intolerance and insulin resistance, we tested whether a liver-specific overexpression of RBP4 in mice impairs glucose homeostasis. We used adeno-associated viruses (AAV) that contain a highly liver-specific promoter to drive expression of murine RBP4 in livers of adult mice. The resulting increase in serum RBP4 levels in these mice was comparable with elevated levels that were reported in obesity. Surprisingly, we found that increasing circulating RBP4 had no effect on glucose homeostasis. Also during a high-fat diet challenge, elevated levels of RBP4 in the circulation failed to aggravate the worsening of systemic parameters of glucose and energy homeostasis. These findings show that liver-secreted RBP4 does not impair glucose homeostasis. We conclude that a modest increase of its circulating levels in mice, as observed in the obese, insulin-resistant state, is unlikely to be a causative factor for impaired glucose homeostasis.
KW  - liver
KW  - retinoid-binding protein
KW  - glucose metabolism
KW  - insulin resistance
KW  - mouse
KW  - TTR
Y1  - 2018
U6  - https://doi.org/10.1074/jbc.RA118.004294
SN  - 1083-351X
VL  - 293
IS  - 39
SP  - 15269
EP  - 15276
PB  - American Society for Biochemistry and Molecular Biology
CY  - Bethesda
ER  - 
TY  - JOUR
A1  - Döll, Stefanie
A1  - Djalali Farahani-Kofoet, Roxana
A1  - Zrenner, Rita
A1  - Henze, Andrea
A1  - Witzel, Katja
T1  - Tissue-specific signatures of metabolites and proteins in asparagus roots and exudates
JF  - Horticulture research
N2  - Comprehensive untargeted and targeted analysis of root exudate composition has advanced our understanding of rhizosphere processes. However, little is known about exudate spatial distribution and regulation. We studied the specific metabolite signatures of asparagus root exudates, root outer (epidermis and exodermis), and root inner tissues (cortex and vasculature). The greatest differences were found between exudates and root tissues. In total, 263 non-redundant metabolites were identified as significantly differentially abundant between the three root fractions, with the majority being enriched in the root exudate and/or outer tissue and annotated as 'lipids and lipid-like molecules' or 'phenylpropanoids and polyketides'. Spatial distribution was verified for three selected compounds using MALDI-TOF mass spectrometry imaging. Tissue-specific proteome analysis related root tissue-specific metabolite distributions and rhizodeposition with underlying biosynthetic pathways and transport mechanisms. The proteomes of root outer and inner tissues were spatially very distinct, in agreement with the fundamental differences between their functions and structures. According to KEGG pathway analysis, the outer tissue proteome was characterized by a high abundance of proteins related to 'lipid metabolism', 'biosynthesis of other secondary metabolites' and 'transport and catabolism', reflecting its main functions of providing a hydrophobic barrier, secreting secondary metabolites, and mediating water and nutrient uptake. Proteins more abundant in the inner tissue related to 'transcription', 'translation' and 'folding, sorting and degradation', in accord with the high activity of cortical and vasculature cell layers in growth- and development-related processes. In summary, asparagus root fractions accumulate specific metabolites. This expands our knowledge of tissue-specific plant cell function.
Y1  - 2021
U6  - https://doi.org/10.1038/s41438-021-00510-5
SN  - 2052-7276
VL  - 8
IS  - 1
PB  - Nanjing Agricultural Univ.
CY  - Nanjing
ER  -