Laboratory of Molecular Biology and Genetics, Department of Gene Technology and Developmental Neurobiology, Institute of Experimental Medicine, Hungarian Academy of Sciences, Budapest, Hungary.
Cell Calcium. 2011 Oct;50(4):381-92. doi: 10.1016/j.ceca.2011.07.002. Epub 2011 Aug 5.
Primary lens epithelial cell (LEC) cultures derived from newborn (P0) and one-month-old (P30) mouse lenses were used to study GABA (gamma-aminobutyric acid) signaling expression and its effect on the intracellular Ca2+ ([Ca2+]i) level. We have found that these cultures express specific cellular markers for lens epithelial and fiber cells, all components of the functional GABA signaling pathway and GABA, thus recapitulating the developmental program of the ocular lens. Activation of both GABA-A and GABA-B receptors (GABAAR and GABABR) with the specific agonists muscimol and baclofen, respectively induces [Ca2+]i transients that could be blocked by the specific antagonists bicuculline and CGP55845 and were dependent on extracellular Ca2+. Bicuculline did not change the GABA-evoked Ca2+ responses in Ca2-containing buffers, but suppressed them significantly in Ca2+-free buffers suggesting the two receptors couple to convergent Ca2+ mobilization mechanisms with different extracellular Ca2+ sensitivity. Prolonged activation of GABABR induced wave propagation of the Ca2+ signal and persistent oscillations. The number of cells reacting to GABA or GABA+bicuculline in P30 mouse LEC cultures expressing predominantly the synaptic type GABAAR did not differ significantly from the number of reacting cells in P0 mouse LEC cultures. The GABA-induced Ca2+ transients in P30 (but not P0) mouse LEC could be entirely suppressed by co-application of bicuculline and CGP55845. The GABA-mediated Ca2+ signaling may be involved in a variety of Ca2+-dependent cellular processes during lens growth and epithelial cell differentiation.
原代培养的新生（P0）和 1 月龄（P30）小鼠晶状体上皮细胞（LEC）用于研究 GABA（γ-氨基丁酸）信号表达及其对细胞内 Ca2+（[Ca2+]i）水平的影响。我们发现这些培养物表达晶状体上皮细胞和纤维细胞的特异性细胞标志物、GABA 信号通路的所有组成部分以及 GABA，从而再现了眼部晶状体的发育程序。用特异性激动剂 muscimol 和 baclofen 分别激活 GABA-A 和 GABA-B 受体（GABAAR 和 GABABR），可诱导 [Ca2+]i 瞬变，该瞬变可被特异性拮抗剂 bicuculline 和 CGP55845 阻断，且依赖于细胞外 Ca2+。Bicuculline 不会改变含 Ca2+缓冲液中 GABA 诱导的 Ca2+反应，但在无 Ca2+缓冲液中显著抑制它们，这表明两种受体通过不同细胞外 Ca2+敏感性的收敛 Ca2+动员机制偶联。GABABR 的持续激活诱导 Ca2+信号的波传播和持续振荡。在主要表达突触型 GABAAR 的 P30 小鼠 LEC 培养物中，对 GABA 或 GABA+bicuculline 有反应的细胞数量与 P0 小鼠 LEC 培养物中反应细胞的数量没有显著差异。在 P30（而非 P0）小鼠 LEC 中，GABA 诱导的 Ca2+瞬变可以完全被 bicuculline 和 CGP55845 的共同应用抑制。GABA 介导的 Ca2+信号可能参与晶状体生长和上皮细胞分化过程中的多种 Ca2+依赖性细胞过程。
