Löffler T, Al-Robaiy S, Bigl M, Eschrich K, Schliebs R
Paul Flechsig Institute for Brain Research, Department of Neurochemistry, Jahnallee 59, D-04109, Leipzig, Germany.
Int J Dev Neurosci. 2001 Jun;19(3):279-85. doi: 10.1016/s0736-5748(01)00011-9.
Fructose-1,6-bisphosphatase is one of the key enzymes in the gluconeogenic pathway predominantly occurring in liver, kidney and muscle. In the brain, fructose-1,6-bisphosphatase has been suggested to be an astrocyte-specific enzyme but the functional importance of glyconeogenesis in the brain is still unclear. To further elucidate the cellular source of fructose-1,6-bisphosphatase in the brain, non-radioactive in situ hybridizations were performed using digoxigenin-labeled RNA probes based on the sequence of recently cloned rat liver and muscle fructose-1,6-bisphosphatase cDNAs. In situ hybridization using a riboprobe for the liver isoform revealed a location of the hybridization signal mainly in neurons, while rat muscle fructose-1,6-bisphosphatase mRNA was detected in both neurons and astrocytes in the hippocampal formation and in layer I of the cerebral cortex.RT-PCR using RNA preparations of rat astrocytes, neurons, and adult whole brain demonstrated a localization of liver fructose-1,6-bisphosphatase mRNA isoform in neurons but not in astrocytes. The muscle fructose-1,6-bisphosphatase mRNA isoform could be detected by RT-PCR in total rat brain, astrocytic, and neuronal mRNA preparations. The isoforms of fructose-1,6-bisphosphatase mRNA seemingly demonstrate a distinct cellular expression pattern in rat brain suggesting a role of glyconeogenesis in both neurons and glial cells.
果糖-1,6-二磷酸酶是糖异生途径中的关键酶之一，主要存在于肝脏、肾脏和肌肉中。在大脑中，果糖-1,6-二磷酸酶被认为是一种星形胶质细胞特异性酶，但糖异生在大脑中的功能重要性仍不清楚。为了进一步阐明大脑中果糖-1,6-二磷酸酶的细胞来源，基于最近克隆的大鼠肝脏和肌肉果糖-1,6-二磷酸酶cDNA序列，使用地高辛标记的RNA探针进行了非放射性原位杂交。使用针对肝脏同工型的核糖探针进行原位杂交显示，杂交信号主要位于神经元中，而在海马结构和大脑皮层I层的神经元和星形胶质细胞中均检测到大鼠肌肉果糖-1,6-二磷酸酶mRNA。使用大鼠星形胶质细胞、神经元和成年全脑的RNA制剂进行的RT-PCR表明，肝脏果糖-1,6-二磷酸酶mRNA同工型定位于神经元而非星形胶质细胞中。通过RT-PCR可以在大鼠全脑、星形胶质细胞和神经元mRNA制剂中检测到肌肉果糖-1,6-二磷酸酶mRNA同工型。果糖-1,6-二磷酸酶mRNA的同工型在大鼠脑中似乎表现出独特的细胞表达模式，表明糖异生在神经元和神经胶质细胞中均起作用。
