Halachmi Sarel, Aitken Karen J, Szybowska Marta, Sabha Nesrin, Dessouki Shariff, Lorenzo Armando, Tse Derrick, Bagli Darius J
Institute of Medical Sciences, The Research Institute, The Hospital for Sick Children, University of Toronto, Toronto, ON, Canada.
Cell Tissue Res. 2006 Oct;326(1):149-58. doi: 10.1007/s00441-006-0204-6. Epub 2006 May 17.
Excessive stretch of the bladder can lead to wall thickening including the growth of bladder smooth muscle cells (BSMC). Only three phospho-proteins (JNK, p38, and PI3K) have been previously shown to participate in stretch-induced BSMC growth. CD1 mouse bladders were hyper- or non-distended by our ex vivo bladder distention model and screened, by a commercial screening method, for phosphorylated signaling proteins. This uncovered a factor previously unexamined for its role in bladder stretch injury: signal transducer and activator of transcription 3 (STAT3). STAT3 was assessed for its role in mitogen- and stretch-induced BSMC proliferation. Proliferation was assessed by 3H-thymidine incorporation/cell counting in response to mitogenic stimulation or to stretch on silastic collagen or carboxyl-coated membranes. JAK2, upstream of STAT3, was inhibited by AG490 (2 microM). Ex vivo distention of bladders activated a discrete number of kinases, including two MAPK pathways (JNK and ERK2) and STAT3. STAT3 signaling was activated during hyperdistention of intact bladder and by stretch and mitogenic treatments of BSMC in vitro. JAK2/STAT3 inhibition by AG490 blocked mitogen- and stretch-induced BSMC proliferation. Thus, BSMC stretch responses may involve the recruitment of both growth factor and mechanically induced BSMC growth responses integrated by a common signaling pathway, STAT3.
膀胱过度伸展可导致膀胱壁增厚，包括膀胱平滑肌细胞（BSMC）的生长。此前仅有三种磷酸化蛋白（JNK、p38和PI3K）被证明参与伸展诱导的BSMC生长。通过我们的体外膀胱扩张模型使CD1小鼠膀胱过度扩张或未扩张，并用商业筛选方法筛选磷酸化信号蛋白。这揭示了一个此前未被研究其在膀胱伸展损伤中作用的因子：信号转导子和转录激活子3（STAT3）。评估了STAT3在有丝分裂原和伸展诱导的BSMC增殖中的作用。通过3H-胸腺嘧啶核苷掺入/细胞计数来评估有丝分裂原刺激或在硅橡胶胶原或羧基包被膜上伸展时的增殖情况。STAT3上游的JAK2被AG490（2 microM）抑制。膀胱的体外扩张激活了一定数量的激酶，包括两条丝裂原活化蛋白激酶（MAPK）途径（JNK和ERK2）以及STAT3。在完整膀胱过度扩张期间以及体外对BSMC进行伸展和有丝分裂原处理时，STAT3信号被激活。AG490对JAK2/STAT3的抑制作用阻断了有丝分裂原和伸展诱导的BSMC增殖。因此，BSMC的伸展反应可能涉及生长因子的募集以及由共同信号通路STAT整合的机械诱导的BSMC生长反应。 3
