Girgenrath Mahasweta, Beermann Mary Lou, Vishnudas Vivek K, Homma Sachiko, Miller Jeffrey Boone
Department of Health Sciences, Boston University, Boston, MA, USA.
Ann Neurol. 2009 Jan;65(1):47-56. doi: 10.1002/ana.21523.
Congenital muscular dystrophy type 1A is an autosomal recessive disease that is caused by loss-of-function mutations in the laminin-alpha2 gene, and results in motor nerve and skeletal muscle dysfunction. In a previous study, we used genetic modifications to show that inappropriate induction of apoptosis was a significant contributor to pathogenesis in a laminin-alpha2-deficient mouse model of congenital muscular dystrophy type 1A. To identify a possible pharmacological therapy for laminin-alpha2 deficiency, we designed this study to determine whether treatment with minocycline or doxycycline, which are tetracycline derivatives reported to have antiapoptotic effects in mammals, would significantly increase lifespan and improve neuromuscular function in laminin-alpha2-deficient mice.
Mice that were homozygous for a targeted, inactivating mutation of the laminin-alpha2 gene were placed into control, minocycline-treated, or doxycycline-treated groups. Drug treatment began within 2 weeks of birth, and the progression of disease was followed over time using behavioral, growth, histological, and molecular assays.
We found that treatment with either minocycline or doxycycline increased the median lifespan of laminin-alpha2-null mice from approximately 32 days to approximately 70 days. Furthermore, doxycycline improved postnatal growth rate and delayed the onset of hind-limb paralysis. Doxycycline-treated laminin-alpha2-deficient muscles had increased Akt phosphorylation, decreased inflammation, and decreased levels of Bax protein, terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling-positive myonuclei, and activated caspase-3.
Doxycycline or other drugs with similar functional profiles may be a possible route to improving neuromuscular dysfunction caused by laminin-alpha2-deficiency.
1A型先天性肌营养不良是一种常染色体隐性疾病，由层粘连蛋白α2基因功能丧失性突变引起，导致运动神经和骨骼肌功能障碍。在先前的一项研究中，我们通过基因改造表明，在1A型先天性肌营养不良的层粘连蛋白α2缺陷小鼠模型中，不适当的凋亡诱导是发病机制的一个重要因素。为了确定针对层粘连蛋白α2缺乏的可能药物治疗方法，我们设计了本研究，以确定用米诺环素或强力霉素治疗是否会显著延长层粘连蛋白α2缺陷小鼠的寿命并改善其神经肌肉功能，米诺环素和强力霉素是据报道在哺乳动物中具有抗凋亡作用的四环素衍生物。
将层粘连蛋白α2基因靶向失活突变的纯合小鼠分为对照组、米诺环素治疗组或强力霉素治疗组。药物治疗在出生后2周内开始，使用行为、生长、组织学和分子检测方法随时间跟踪疾病进展。
我们发现，米诺环素或强力霉素治疗均将层粘连蛋白α2基因缺失小鼠的中位寿命从约32天延长至约70天。此外，强力霉素提高了出生后的生长速度，并延迟了后肢麻痹的发作。强力霉素治疗的层粘连蛋白α2缺陷肌肉中，Akt磷酸化增加，炎症减轻，Bax蛋白水平、末端脱氧核苷酸转移酶介导的dUTP缺口末端标记阳性肌核和活化的半胱天冬酶-3水平降低。
强力霉素或其他具有类似功能特征的药物可能是改善由层粘连蛋白α2缺乏引起的神经肌肉功能障碍的一种可能途径。
