Smad9是一种重要的转录因子,属于Smad蛋白家族,是骨形态发生蛋白(BMP)信号通路中的关键成员。Smad9(也称为Smad8)与Smad1和Smad5一样,可以被BMP结合的I型受体激酶磷酸化激活。与其他Smad蛋白不同,Smad9在BMP信号通路中扮演着一种独特的转录调节角色。尽管Smad9与Smad1和Smad5都能与Smad4结合并绑定到目标DNA上,但Smad9的转录活性较低。Smad9的表达会随着BMP信号的激活而增加,类似于抑制性Smad(I-Smads),并且Smad9能够减少BMP活性。与其他I-Smads不同,Smad9并不抑制I型受体激酶,而是通过结合Smad1来抑制转录活性。因此,Smad9在BMP信号通路中是一种新型的转录调节因子[4]。
在人类疾病中,Smad9基因的变异与多种疾病相关。研究发现,Smad9基因中的单核苷酸多态性(SNPs)与汉族人群中的高血压风险增加相关[1]。此外,Smad9基因的罕见突变与高骨量(HBM)相关,这表明Smad9基因可能是骨质疏松症治疗的潜在靶点[5]。此外,Smad9基因的变异还与肺动脉高压(PAH)相关,PAH是一种罕见的进行性血管病变,具有显著的心肺疾病负担和死亡率[3][7]。研究表明,Smad9基因的变异可能是PAH发生和发展的关键因素之一。
在神经母细胞瘤(NB)中,Smad9蛋白的表达与MYCN基因的扩增相关。MYCN基因是一种重要的NB风险决定因素,高表达MYCN基因的NB患者预后较差。研究发现,SMAD9与MYCN之间存在正反馈调节环,SMAD9的表达受到MYCN、PHOX2B、GATA3和HAND2等转录因子的诱导。此外,SMAD9还能够结合到MYCN启动子上,转录调节MYCN的表达。因此,SMAD9在MYCN扩增的NB中具有独特的依赖性,可能是NB治疗的新靶点[2][9]。
在禽类中,Smad9基因也被发现与产蛋性能相关。研究发现,Smad9基因的变异与鹅的产蛋性能相关,Smad9基因的某些变异型与更高的产蛋量相关。此外,Smad9基因的表达与鹅卵泡的选择和发育相关,可能通过调节促黄体生成素受体(LHR)的表达来影响鹅卵泡的选择[6][8]。
综上所述,Smad9基因在多种生物学过程中发挥着重要作用,包括BMP信号通路、高血压、高骨量、肺动脉高压、神经母细胞瘤和禽类产蛋性能等。Smad9基因的变异与多种疾病的发生和发展相关,可能是疾病治疗和预防的新靶点。未来,对Smad9基因的进一步研究将有助于深入理解其在不同生物学过程中的作用机制,为疾病的治疗和预防提供新的思路和策略。
参考文献:
1. Chen, Yunpeng, Ye, Chenxi, Chen, Jingwen, Wang, Hao, Wang, Shen. 2019. Association of the gene polymorphisms of BMPR2, ACVRL1, SMAD9 and their interactions with the risk of essential hypertension in the Chinese Han population. In Bioscience reports, 39, . doi:10.1042/BSR20181217. https://pubmed.ncbi.nlm.nih.gov/30617053/
2. Tan, Kezhe, Mo, Jialin, Li, Meng, Tang, Yujie, Lv, Zhibao. 2022. SMAD9-MYCN positive feedback loop represents a unique dependency for MYCN-amplified neuroblastoma. In Journal of experimental & clinical cancer research : CR, 41, 352. doi:10.1186/s13046-022-02563-3. https://pubmed.ncbi.nlm.nih.gov/36539767/
3. Welch, Carrie L, Aldred, Micheala A, Balachandar, Srimmitha, Tenorio-Castano, Jair, Chung, Wendy K. 2023. Defining the clinical validity of genes reported to cause pulmonary arterial hypertension. In Genetics in medicine : official journal of the American College of Medical Genetics, 25, 100925. doi:10.1016/j.gim.2023.100925. https://pubmed.ncbi.nlm.nih.gov/37422716/
4. Tsukamoto, S, Mizuta, T, Fujimoto, M, Kokabu, S, Katagiri, T. 2014. Smad9 is a new type of transcriptional regulator in bone morphogenetic protein signaling. In Scientific reports, 4, 7596. doi:10.1038/srep07596. https://pubmed.ncbi.nlm.nih.gov/25534700/
5. Gregson, Celia L, Bergen, Dylan J M, Leo, Paul, Tobias, Jon H, Duncan, Emma L. 2019. A Rare Mutation in SMAD9 Associated With High Bone Mass Identifies the SMAD-Dependent BMP Signaling Pathway as a Potential Anabolic Target for Osteoporosis. In Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research, 35, 92-105. doi:10.1002/jbmr.3875. https://pubmed.ncbi.nlm.nih.gov/31525280/
6. Xu, Jun, Li, Jun, Wang, Haosen, Wang, Zhao, Cai, Yafei. 2014. A novel SMAD family protein, SMAD9 is involved in follicular initiation and changes egg yield of geese via synonymous mutations in exon1 and intron2. In Molecular biology reports, 42, 289-302. doi:10.1007/s11033-014-3772-7. https://pubmed.ncbi.nlm.nih.gov/25280542/
7. Eichstaedt, Christina A, Saßmannshausen, Zoe, Shaukat, Memoona, Hinderhofer, Katrin, Grünig, Ekkehard. 2022. Gene panel diagnostics reveals new pathogenic variants in pulmonary arterial hypertension. In Respiratory research, 23, 74. doi:10.1186/s12931-022-01987-x. https://pubmed.ncbi.nlm.nih.gov/35346192/
8. Yu, Daolun, Zhang, Li, Wang, Hejian, Li, Jun, Cai, Yafei. 2018. A potential role for SMAD9 in goose follicular selection through regulation of mRNA levels of luteinizing hormone receptor. In Theriogenology, 135, 204-212. doi:10.1016/j.theriogenology.2018.11.022. https://pubmed.ncbi.nlm.nih.gov/30522699/
9. Zhang, Liaoran, Mo, Jialin, Shi, Hao, Lv, Zhibao, Tan, Kezhe. 2024. CRISPR-Cas9 screening develops an epigenetic and transcriptional gene signature for risk stratification and target prediction in neuroblastoma. In Frontiers in cell and developmental biology, 12, 1433008. doi:10.3389/fcell.2024.1433008. https://pubmed.ncbi.nlm.nih.gov/39175876/