Potential link between the NIMA mitotic kinase and nuclear membrane fission during mitotic exit in Aspergillus nidulans
Potential link between the NIMA mitotic kinase and nuclear membrane fission during mitotic exit in Aspergillus nidulans
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DOI：
10.1128/ec.3.6.1433-1444.2004
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发表时间：
2004-12-01
期刊：
影响因子：
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通讯作者：
Osmani, SA
中科院分区：
文献类型：
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作者：
Davies, JR;Osmani, AH;Osmani, SA
我们利用酵母双杂交系统分离了TINC作为NIMA相互作用蛋白，并证实了TINC在构巢曲霉中与NIMA相互作用。TINC-NIMA相互作用在不存在磷酸酶抑制剂和存在激酶失活NIMA的情况下稳定，表明当NIMA未完全激活时相互作用增强。TINC是一种细胞质蛋白。TINC同源物和TINC样蛋白（A. nidulans HETC）在其它丝状真菌中是保守的。tinC的缺失或tinC和A两者的缺失均不存在。nidulans hetC是致死的，但tinC的缺失确实产生冷敏感性以及渗透敏感性。氨基末端截短形式的TINC（DeltaN-TINC）的表达抑制曲霉属中的菌落生长并定位于细胞内的膜样结构。对这些细胞的细胞周期进程的检查表明，它们通过多个有缺陷的有丝分裂而进展。许多细胞含有大的多倍体单核，而有些细胞似乎有分离的DNA块。对含有多个DNA质量的细胞的核膜进行检查，发现两个DNA质量都包含在单个核膜内，这表明核膜裂变是有缺陷的。这些细胞将DNA分离与核膜分裂分开的能力表明，这种协调在A. nidulans。另外的实验证明，DeltaN-TINC的表达导致有丝分裂样品中的过早NIMA消失。我们建议，TINC的相互作用与NIMA和DeltaN-TINC表达产生的细胞周期缺陷表明TINC和NIMA在核膜分裂过程中可能的作用。
We have isolated TINC as a NIMA-interacting protein by using the yeast two-hybrid system and have confirmed that TINC interacts with NIMA in Aspergillus nidulans. The TINC-NIMA interaction is stabilized in the absence of phosphatase inhibitors and in the presence of kinase-inactive NIMA, suggesting that the interaction is enhanced when NIMA is not fully activated. TINC is a cytoplasmic protein. TINC homologues and a TINC-like protein (A. nidulans HETC) are conserved in other filamentous fungi. Neither deletion of tinC nor deletion of both tinC and A. nidulans hetC is lethal, but deletion of tinC does produce cold sensitivity as well as osmotic sensitivity. Expression of an amino-terminal-truncated form of TINC (DeltaN-TINC) inhibits colony growth in Aspergillus and localizes to membrane-like structures within the cell. Examination of cell cycle progression in these cells reveals that they progress through multiple defective mitoses. Many cells contain large polyploid single nuclei, while some appear to have separated masses of DNA. Examination of the nuclear envelopes of cells containing more than one DNA mass reveals that both DNA masses are contained within a single nuclear envelope, indicating that nuclear membrane fission is defective. The ability of these cells to separate DNA segregation from nuclear membrane fission suggests that this coordination is normally a regulated process in A. nidulans. Additional experiments demonstrate that expression of DeltaN-TINC results in premature NIMA disappearance in mitotic samples. We propose that TINC's interaction with NIMA and the cell cycle defects produced by DeltaN-TINC expression suggest possible roles for TINC and NIMA during nuclear membrane fission.