Camarillo I G, Linebaugh B E, Rillema J A
Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan 48201, USA.
Proc Soc Exp Biol Med. 1997 Jun;215(2):198-202. doi: 10.3181/00379727-215-44129.
Prolactin (PRL) stimulates mitogenesis and differentiative processes in a variety of cell types. Not all of the molecules involved in PRL signaling, which follows an initial PRL-receptor interaction, have been identified. In the present studies, PRL is shown to stimulate the differential tyrosyl phosphorylation of three isoforms (ERK-1, 2, and 4) of mitogen-activated protein kinases (MAP kinase) in a rat pre-T lymphoma cell line (Nb2). Evidence also suggests that PRL stimulates the tyrosyl phosphorylation of ERK-3, a MAP kinase isoform recently identified. When G1-arrested Nb2 cells are treated with 50 ng/ml oPRL, ERK-1 through 3 become tyrosyl phosphorylated within minutes (an indication of enzyme activation) and then become dephosphorylated within 30 min. Conversely, ERK-4 is rapidly tyrosyl phosphorylated by 5 min, and remains in this state for at least 1 hr.
催乳素（PRL）可刺激多种细胞类型的有丝分裂和分化过程。并非所有参与PRL信号传导（其始于最初的PRL-受体相互作用）的分子都已被鉴定出来。在本研究中，PRL被证明可刺激大鼠前T淋巴瘤细胞系（Nb2）中丝裂原活化蛋白激酶（MAP激酶）的三种同工型（ERK-1、2和4）发生差异性酪氨酰磷酸化。证据还表明，PRL可刺激最近鉴定出的一种MAP激酶同工型ERK-3的酪氨酰磷酸化。当用50 ng/ml的oPRL处理处于G1期阻滞的Nb2细胞时，ERK-1至3在数分钟内发生酪氨酰磷酸化（这是酶激活的标志），然后在30分钟内发生去磷酸化。相反，ERK-4在5分钟内迅速发生酪氨酰磷酸化，并至少保持这种状态1小时。
