MOLECULAR MECHANISM FOR ERECTILE FUNCTION & DYSFUNCTION

勃起(勃起)是一种复杂的神经生理事件，导致 松弛海绵体内的平滑肌细胞 阴茎，允许血液注入海绵状空间，导致 阴茎的大小和硬度的增加。软弱性 (消肿)是由收缩启动和维持的 海绵体平滑肌细胞。CCSM是唯一的 因为它大部分时间都保持在收缩状态。它不是 知道是钙-钙调蛋白-MLCK途径还是其他细丝- 介导的调节(通过肌动蛋白结合蛋白caldesmon)发挥作用 在保持这些细胞处于收缩状态中的作用，因为阴茎 保持疲软状态。第三种可能性是肌球蛋白在 CCSM在决定力的产生速度和速度方面发挥作用 音调。 这位研究人员最近进行的一项研究表明，主动脉 被认为是补品的平滑肌含有一种肌球蛋白 而小肌肉动脉中的平滑肌细胞是同型的 含有不同的肌球蛋白亚型。后一种亚型的编码方式为 肌球蛋白重链mRNA，可选择性剪接以插入 编码ATP结合区附近区域的21-核苷酸序列 肌球蛋白头上的位置。该插入片段编码7个氨基酸的多肽， 由此产生的肌球蛋白亚型在 肌动蛋白激活的肌球蛋白ATPase活性和相关的增加 缩短速度(Vmax)。对CCSM的类似研究在我们的 实验室表明，CCSM包含两个插入(如在小肌肉 动脉和所有内脏平滑肌均呈相位性 特征)和非插入的(如在主动脉平滑肌中 是补药)肌球蛋白重链亚型。 特别是，使用来自正常兔、正常人类和 勃起功能障碍患者，我们将解决以下问题 问题：(1)收缩特性有何不同？ CCSM与其他来源的平滑肌相比，由于 平滑肌肌球蛋白亚型组成的差异 是通过在3‘端选择性剪接肌球蛋白前体mRNA而产生的 末端(导致SM1和SM2)或5‘末端(导致插入 肌球蛋白轻链磷酸化起什么作用？ 在勃起功能和CCSM细胞是否有更高或更低的激酶 磷酸酶活性与其他平滑肌细胞相比(例如： (3)膀胱平滑肌的表达水平是什么？ 肌球蛋白轻链激酶和钙调蛋白在CCSM中的表达及其改变 在勃起功能障碍患者中？因此，结果来自于 在本申请中提出的实验将提供分子 CCSM收缩的调节机制和DILEAT 跨桥骑行路径的具体步骤和 正常体腔内平滑肌细胞的收缩特性 阴茎海绵体。它还将为更改提供和解释 慢性阻塞性肺疾病患者血管平滑肌细胞收缩功能的改变 勃起功能障碍。

Erection(tumescence) is a complex neurophysiologic event that leads to relaxation of the smooth muscle cells in the corpus cavernosum penis which allows filling of blood into the cavernous spaces causing an increase in the size and rigidity of the penis. Flaccidity (detumescence) is initiated and maintained by contraction of the corpus cavernosum smooth muscle (CCSM) cells. The CCSM is unique since it remains in the contracted state most of the time. It is not know whether the Ca2+-calmodulin-MLCK pathway or other then filament- mediated regulation (via the actin-binding protein caldesmon) plays a role in keeping these cells in the contracted state, for the penis to remain flaccid. A third possibility is that the myosin isoforms in CCSM play a role in determining the velocity of force generation and the tonicity. A recent study conducted by this investigator showed that the aortic smooth muscle, which is considered tonic, contains one type of myosin isoform whereas the smooth muscle cells in small muscular arteries contain a different myosin isoform. The latter isoform is encoded by a myosin heavy chain mRNA that is alternatively spliced to insert a 21-nucleotide sequence that encodes a region near the ATP-binding site on the myosin head. This insert encodes a 7-amino acid peptide, and the resulting myosin isoform has a two-fold increase in the actin-activated myosin ATPase activity and an associated increase in shortening velocity (Vmax). Similar studies conducted on CCSM in our lab show that the CCSM contains both inserted (as in small muscular arteries and all visceral smooth muscles which show phasic characteristics) and non-inserted (as in aortic smooth muscle which is tonic) myosin heavy chain isoforms. Specially, using CCSM from normal rabbits, normal humans, and patients with erectile dysfunctions, we will address the following questions: (1) Are the differences in the contractile characteristics of CCSM compared to smooth muscle from other sources due to a difference in the composition of smooth muscle myosin isoforms that are produced by alternative splicing of the myosin pre-mRNA at the 3' end (resulting in SM1 and SM2) or the 5' end (resulting in inserted myosin)? (2) What role does myosin light chain phosphorylation play in erectile function and do CCSM cells have higher kinase or lower phosphatase activity compared to other smooth muscle cells (e.g. bladder smooth muscle)? (3) What is the level of expression of myosin light chain kinase and caldesmon in the CCSM and is it altered in patients with erectile dysfunction? Thus, the results from experiments proposed in this application will provide the molecular mechanisms for the regulation of CCSM contraction and delineate specific steps in the pathways for cross-bridge cycling and contractility of smooth muscle cells in the normal corporus cavernosum penis. It will also provide and explanation for changes in contractility of smooth muscle cells seen in patients with erectile dysfunction.