Data Supplement for "Upregulated Phospholipase D Activity Towards Glycosylphosphatidylinositol-Anchored Proteins in Micelle-Like Serum Complexes in Metabolically Deranged Rats and Humans"

Data Supplement for Publication

Glycosylphosphatidylinositol-anchored proteins (GPI-AP)
with the complete glycolipid anchor attached have previously been shown to be
released from the outer plasma membrane leaflet of rat adipocytes in positive correlation
to cell size and blood glucose/insulin levels of the donor rats. Furthermore,
they are present in rat and human serum, however, at amounts which are lower in
insulin-resistant/obese rats compared to normal ones. These findings prompted
further evaluation of the potential of full-length GPI-AP for the prediction
and stratification of metabolically deranged states. A comparison of the signatures
of horizontal surface acoustic waves which were generated by full-length GPI-AP
in course of their specific capture by and subsequent dissociation from a
chip-based sensor between those from rat serum and those reconstituted into
lipidic structures strongly argues for expression of full-length GPI-AP in
serum in micelle-like complexes in concert with phospholipids,
lysophospholipids and cholesterol. Both the reconstituted and the rat serum
complexes were highly sensitive towards mechanical forces, such as vibration.
Furthermore, full-length GPI-AP reconstituted into micelle-like complexes
represented efficient substrates for cleavage by serum
glycosylphosphatidylinositol-specific phospholipase D (GPI-PLD). These findings
raised the possibility that the upregulated release of full-length GPI-AP into
micelle-like serum complexes from metabolically deranged cells is compensated
by elevated GPI-PLD activity. In fact, serum GPI-PLD activity towards full-length
GPI-AP in micelle-like complexes, but not in detergent micelles, was positively
correlated to early states of insulin resistance and obesity in genetic and
diet-induced rat models as well as to the body weight in humans. Moreover, the differences
in the degradation of GPI-AP in micelle-like complexes were found to rely in
part on the interaction of serum GPI-PLD with an activating serum factor. These
data suggest, that serum GPI-PLD activity measured with GPI-AP in micelle-like
complexes is indicative of enhanced release of full-length GPI-AP from relevant
tissues into the circulation as a consequence of early metabolic derangement in
rats and humans.

本补充数据集针对糖基磷脂酰肌醇锚定蛋白（GPI-AP）进行研究，该蛋白在其完整的糖基脂锚定作用下，已证实能够从大鼠脂肪细胞的质膜外叶释放，其释放程度与供体大鼠的细胞大小及血糖/胰岛素水平呈正相关。此外，GPI-AP亦存在于大鼠和人类血清中，但在胰岛素抵抗/肥胖大鼠中的含量较正常大鼠低。这些发现促使进一步评估全长GPI-AP在预测和分层代谢紊乱状态中的潜力。通过比较全长GPI-AP在特定捕获和随后的从基于芯片的传感器解离过程中产生的水平表面声波特征，与重构到脂质结构中的大鼠血清之间的差异，有力地支持了全长GPI-AP在血清中以胶束样复合物形式与磷脂、溶血磷脂和胆固醇共同表达的观点。重构的大鼠血清复合物对机械力，如振动，表现出高度敏感性。此外，重构到胶束样复合物中的全长GPI-AP是血清中糖基磷脂酰肌醇特异性磷脂酶D（GPI-PLD）切割的有效底物。这些发现提出了这样一种可能性，即代谢紊乱细胞中全长GPI-AP向胶束样血清复合物的释放增加，可通过GPI-PLD活性的升高得到补偿。事实上，在胶束样复合物中，而非洗涤剂胶束中，血清GPI-PLD活性与早期胰岛素抵抗和肥胖的遗传和饮食诱导的大鼠模型以及人类的体重呈正相关。此外，研究发现，在胶束样复合物中GPI-AP降解的差异部分依赖于血清GPI-PLD与激活血清因子的相互作用。这些数据表明，使用GPI-AP在胶束样复合物中测量的血清GPI-PLD活性是大鼠和人类早期代谢紊乱导致相关组织全长GPI-AP释放增加的指示器。