Patterns of importin-α expression during Drosophila spermatogenesis
Patterns of importin-α expression during Drosophila spermatogenesis
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DOI：
10.1016/s1047-8477(02)00543-9
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发表时间：
2002-10-01
影响因子：
3
通讯作者：
Mechler, BM
中科院分区：
文献类型：
--
作者：
Giarrè, M;Török, I;Mechler, BM
importin - α蛋白不仅介导嗜核蛋白的细胞核输入，还调节有丝分裂过程中的纺锤体组装和果蝇卵发生过程中的环管组装。果蝇的基因组中存在三个importin- α基因。为了进一步了解它们的功能，我们使用针对果蝇中发现的三种importin - α蛋白（即Imp-alpha1、-alpha2和-alpha3）的抗体分析了它们在精子发生过程中的表达。我们发现每个imp - α在精子发生的特定和有限的时期内表达。Imp-alpha2的强表达发生在精原细胞中，持续存在于精母细胞中，并持续到减数分裂完成。在生长中的精母细胞中，Imp-alpha2的细胞内定位似乎依赖于细胞生长的速度。在蛹睾丸中，Imp-alpha2主要存在于精母细胞细胞核中，但也存在于成年睾丸精母细胞的细胞质中。Imp-alpha1和-alpha3的表达始于减数分裂开始，结束于精细胞分化。Imp-alpha1的表达一直延续到延伸期的开始，而Imp-alpha3的表达一直持续到精子个体化时核凝聚完成。在减数分裂期间，Imp-alpha1和-alpha3分散在核质中，它们部分与核纺锤体相关，尽管与母核无关。在末期，它们聚集在染色质周围。在精子头分化过程中，Imp-alpha1和-alpha3都是核细胞。这些数据表明，在果蝇精子发生过程中，每种imp - α蛋白携带不同的功能，尽管重叠，这些功能可能涉及蛋白质的核输入、微管组织和其他未知的过程。(C) 2002 Elsevier Science （USA）。版权所有。
Importin-alpha proteins do not only mediate the nuclear import of karyophilic proteins but also regulate spindle assembly during mitosis and the assembly of ring canals during Drosophila oogenesis. Three importin-alpha genes are present in the genome of Drosophila. To gain further insights into their function we analysed their expression during spermatogenesis by using antibodies raised against each of the three Importin-alpha proteins identified in Drosophila, namely, Imp-alpha1, -alpha2, and -alpha3. We found that each Imp-alpha is expressed during a specific and limited period of spermatogenesis. Strong expression of Imp-alpha2 takes place in spermatogonial cells, persists in spermatocytes, and lasts up to the completion of meiosis. In growing spermatocytes, the intracellular localisation of Imp-alpha2 appears to be dependent upon the rate of cell growth. In pupal testes Imp-alpha2 is essentially present in the spermatocyte nucleus but is localised in the cytoplasm of spermatocytes from adult testes. Both Imp-alpha1 and -alpha3 expression initiates at the beginning of meiosis and ends during spermatid differentiation. Imp-alpha1 expression extends up to the onset of the elongation phase, whereas that of Imp-alpha3 persists up to the completion of nuclear condensation when the spermatids become individualised. During meiosis Imp-alpha1 and -alpha3 are dispersed in the karyoplasm where they are partially associated with the nuclear spindle, albeit not with the asters. At telophase they aggregate around the chromatin. During sperm head differentiation, both Imp-alpha1 and -alpha3 are nuclear. These data indicate that each Imp-alpha protein carries during Drosophila spermatogenesis distinct, albeit overlapping, functions that may involve nuclear import of proteins, microtubule organisation, and other yet unknown processes. (C) 2002 Elsevier Science (USA). All rights reserved.