Deregulated miR-29b-3p Correlates with Tissue-Specific Activation of Intrinsic Apoptosis in An Animal Model of Amyotrophic Lateral Sclerosis

Abstract

Amyotrophic lateral sclerosis (ALS) is one of the most common incurable motor neuron disorders in adults. The majority of all ALS cases occur sporadically (sALS). Symptoms of ALS are caused by a progressive degeneration of motor neurons located in the motor cortex and spinal cord. The question arises why motor neurons selectively degenerate in ALS, while other cells and systems appear to be spared the disease. Members of the intrinsic apoptotic pathway are frequent targets of altered microRNA expression. Therefore, microRNAs and their effects on cell survival are subject of controversial debates. In this study, we investigated the expression of numerous members of the intrinsic apoptotic cascade by qPCR, western blot, and immunostaining in two different regions of the CNS of wobbler mice. Further we addressed the expression of miR-29b-3p targeting BMF, Bax, and, Bak, members of the apoptotic pathway. We show a tissue-specific differential expression of BMF, Bax, and cleaved-Caspase 3 in wobbler mice. An opposing regulation of miR-29b-3p expression in the cerebellum and cervical spinal cord of wobbler mice suggests different mechanisms regulating the intrinsic apoptotic pathway. Based on our findings, it could be speculated that miR-29b-3p might regulate antiapoptotic survival mechanisms in CNS areas that are not affected by neurodegeneration in the wobbler mouse ALS model.

Caffeine and NAD+ Improve Motor Neural Integrity of Dissociated Wobbler Cells In Vitro

“…Recently, the link between neuron degeneration in wobbler mice and the apoptotic pathways including caspase activity was investigated by the authors in [45]. Considering that caspase 3 and 6 were proven to show a coordinated activation in the apoptosis of cerebellar granule cells [60], the results within the mentioned study, such as an increased activeness of caspase 3, agree with previous assumptions [45].…”

“…While there was found to be various pathological phenomena within the wobbler mouse, such as an enlargement of endosomal vesicles [ 11 ], an impairment of the anterograde and retrograde axonal transport [ 43 ] or a mitochondrial dysfunction [ 44 ], there is still a lack of investigations regarding the beginning of the degenerative causal chain. The Vps54 gene defect is not yet sufficient to explain all cellular pathologies within the wobbler motor neurons [ 10 , 45 ]. By isolating the cells of the ventral horn from remaining tissues and compartments of the organism, we were able to create standardized conditions and independence from potential systemic triggers.…”

“…Since the Golgi apparatus was also described to play a fundamental role in the pathogenesis of the wobbler and human ALS disease in a sense of a structural and functional disorder [ 10 , 11 , 59 ], the connection between Nmnat2 and the Golgi apparatus appears relevant to explain Nmnat2 effects on wobbler motor neurons. Recently, the link between neuron degeneration in wobbler mice and the apoptotic pathways including caspase activity was investigated by the authors in [ 45 ]. Considering that caspase 3 and 6 were proven to show a coordinated activation in the apoptosis of cerebellar granule cells [ 60 ], the results within the mentioned study, such as an increased activeness of caspase 3, agree with previous assumptions [ 45 ].…”

Vps54 Regulates Lifespan and Locomotor Behavior in Adult Drosophila melanogaster

“…One of the primary objectives of this study was to determine whether disruption of scat expression in adult flies caused phenotypes like those observed in the wobbler mouse. While mutations in Vps54 have not been directly linked to human disease, the wobbler mouse has been used by many researchers as a model for the sporadic form of ALS because of striking similarities to ALS pathology ( Ikeda et al, 1998 ; Dennis and Citron, 2009 ; Nieto-Gonzalez et al, 2011 ; Moser et al, 2013 ; Dahlke et al, 2015 ; Schmitt-John, 2015 ; Klatt et al, 2019 ; Rohm et al, 2019 ; Cihankaya et al, 2021 ; De Nicola et al, 2021 ). It has previously been shown that scat mutants share spermatogenesis defects caused by Golgi dysfunction with the wobbler mouse ( Castrillon et al, 1993 ; Fari et al, 2016 ).…”

RNA Deregulation in Amyotrophic Lateral Sclerosis: The Noncoding Perspective

“…In ALS mouse SCs, miR-29a is upregulated by the ER stress-induced TF ATF4 [ 126 ], causing the downregulation of the antiapoptotic factor Mcl-1 [ 127 ]. In the wobbler mouse, it was reported that miR-29b-3p overexpression downregulated the proapoptotic factors BAK, BAX, and BMF, leading to apoptosis and, thus, to neurodegeneration [ 128 ]. Li et al [ 129 ] demonstrated, instead, that the downregulation of miR-193b-3p—reported in sALS patients as well [ 130 ]—promoted cell death in the ALS SOD1 G93A mouse.…”