Spinal muscular atrophy (SMA) is a hereditary neurodegenerative disease with severity ranging from progressive infantile paralysis and premature death (type I) to limited motor neuron loss and normal life expectancy (type IV). Without disease‐modifying therapies, the impact is profound for patients and their families. Improved understanding of the molecular basis of SMA, disease pathogenesis, natural history, and recognition of the impact of standardized care on outcomes has yielded progress toward the development of novel therapeutic strategies and are summarized. Therapeutic strategies in the pipeline are appraised, ranging from SMN1 gene replacement to modulation of SMN2 encoded transcripts, to neuroprotection, to an expanding repertoire of peripheral targets, including muscle. With the advent of preliminary trial data, it can be reasonably anticipated that the SMA treatment landscape will transform significantly. Advancement in presymptomatic diagnosis and screening programs will be critical, with pilot newborn screening studies underway to facilitate preclinical diagnosis. The development of disease‐modifying therapies will necessitate monitoring programs to determine the long‐term impact, careful evaluation of combined treatments, and further acceleration of improvements in supportive care. In advance of upcoming clinical trial results, we consider the challenges and controversies related to the implementation of novel therapies for all patients and set the scene as the field prepares to enter an era of novel therapies. Ann Neurol 2017;81:355–368

Studies examining gene expression with RT-PCR typically normalize their mRNA data to a constitutively expressed housekeeping gene. The validity of a particular housekeeping gene must be determined for each experimental intervention. We examined the expression of various housekeeping genes following an acute bout of endurance (END) or resistance (RES) exercise. Twenty-four healthy subjects performed either a interval-type cycle ergometry workout to exhaustion ( approximately 75 min; END) or 300 single-leg eccentric contractions (RES). Muscle biopsies were taken before exercise and 3 h and 48 h following exercise. Real-time RT-PCR was performed on beta-actin, cyclophilin (CYC), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and beta2-microglobulin (beta2M). In a second study, 10 healthy subjects performed 90 min of cycle ergometry at approximately 65% of Vo(2 max), and we examined a fifth housekeeping gene, 28S rRNA, and reexamined beta2M, from muscle biopsy samples taken immediately postexercise. We showed that CYC increased 48 h following both END and RES exercise (3- and 5-fold, respectively; P < 0.01), and 28S rRNA increased immediately following END exercise (2-fold; P = 0.02). beta-Actin trended toward an increase following END exercise (1.85-fold collapsed across time; P = 0.13), and GAPDH trended toward a small yet robust increase at 3 h following RES exercise (1.4-fold; P = 0.067). In contrast, beta2M was not altered at any time point postexercise. We conclude that beta2M and beta-actin are the most stably expressed housekeeping genes in skeletal muscle following RES exercise, whereas beta2M and GAPDH are the most stably expressed following END exercise.

The t(11;14)(q13;q32) translocation has been associated with human B-lymphocytic malignancy. Several examples of this translocation have been cloned, documenting that this abnormality joins the immunoglobulin heavy-chain gene to the bcl-1 locus on chromosome 11. However, the identification of the bcl-1 gene, a putative dominant oncogene, has been elusive. In this work, we have isolated genomic clones covering 120 kb of the bcl-1 locus. Probes from the region of an HpaII-tiny-fragment island identified a candidate bcl-1 gene. cDNAs representing the bcl-1 mRNA were cloned from three cell lines, two with the translocation. The deduced amino acid sequence from these clones showed bcl-1 to be a member of the cyclin gene family. In addition, our analysis of expression of bcl-1 in an extensive panel of human cell lines showed it to be widely expressed except in lymphoid or myeloid lineages. This observation may provide a molecular basis for distinct modes of cell cycle control in different mammalian tissues. Activation of the bcl-1 gene may be oncogenic by directly altering progression through the cell cycle.

The transcription factor signal transducer and activator of transcription 3 (STAT3) has been identified as a mediator of cytokine signaling and implicated in hypertrophy; however, the importance of this pathway following resistance exercise in human skeletal muscle has not been investigated. In the present study, the phosphorylation and nuclear localization of STAT3, together with STAT3-regulated genes, were measured in the early recovery period following intense resistance exercise. Muscle biopsy samples from healthy subjects (7 males, 23.0 + 0.9 yr) were harvested before and again at 2, 4, and 24 h into recovery following a single bout of maximal leg extension exercise (3 sets, 12 repetitions). Rapid and transient activation of phosphorylated (tyrosine 705) STAT3 was observed at 2 h postexercise. STAT3 phosphorylation paralleled the transient localization of STAT3 to the nucleus, which also peaked at 2 h postexercise. Downstream transcriptional events regulated by STAT3 activation peaked at 2 h postexercise, including early responsive genes c-FOS (800-fold), JUNB (38-fold), and c-MYC (140-fold) at 2 h postexercise. A delayed peak in VEGF (4-fold) was measured 4 h postexercise. Finally, genes associated with modulating STAT3 signaling were also increased following exercise, including the negative regulator SOCS3 (60-fold). Thus, following a single bout of intense resistance exercise, a rapid phosphorylation and nuclear translocation of STAT3 are evident in human skeletal muscle. These data suggest that STAT3 signaling is an important common element and may contribute to the remodeling and adaptation of skeletal muscle following resistance exercise.

. Interaction of contractile activity and training history on mRNA abundance in skeletal muscle from trained athletes. Am J Physiol Endocrinol Metab 290: E849 -E855, 2006. First published December 6, 2005 doi:10.1152/ajpendo.00299.2005.-Skeletal muscle displays enormous plasticity to respond to contractile activity with muscle from strength-(ST) and endurance-trained (ET) athletes representing diverse states of the adaptation continuum. Training adaptation can be viewed as the accumulation of specific proteins. Hence, the altered gene expression that allows for changes in protein concentration is of major importance for any training adaptation. Accordingly, the aim of the present study was to quantify acute subcellular responses in muscle to habitual and unfamiliar exercise. After 24-h diet/exercise control, 13 male subjects (7 ST and 6 ET) performed a random order of either resistance (8 ϫ 5 maximal leg extensions) or endurance exercise (1 h of cycling at 70% peak O 2 uptake). Muscle biopsies were taken from vastus lateralis at rest and 3 h after exercise. Gene expression was analyzed using real-time PCR with changes normalized relative to preexercise values. After cycling exercise, peroxisome proliferator-activated receptor-␥ coactivator-1␣ (ET ϳ8.5-fold, ST ϳ10-fold, P Ͻ 0.001), pyruvate dehydrogenase kinase-4 (PDK-4; ET ϳ26-fold, ST ϳ39-fold), vascular endothelial growth factor (VEGF; ET ϳ4.5-fold, ST ϳ4-fold), and muscle atrophy F-box protein (MAFbx) (ET ϳ2-fold, ST ϳ0.4-fold) mRNA increased in both groups, whereas MyoD (ϳ3-fold), myogenin (ϳ0.9-fold), and myostatin (ϳ2-fold) mRNA increased in ET but not in ST (P Ͻ 0.05). After resistance exercise PDK-4 (ϳ7-fold, P Ͻ 0.01) and MyoD (ϳ0.7-fold) increased, whereas MAFbx (ϳ0.7-fold) and myostatin (ϳ0.6-fold) decreased in ET but not in ST. We conclude that prior training history can modify the acute gene responses in skeletal muscle to subsequent exercise. cycling; resistance exercise; training; adaptation SKELETAL MUSCLE DISPLAYS AN ENORMOUS PLASTICITY to respond to contractile activity and loading conditions, with muscle from strength-(ST) and endurance-trained (ET) athletes representing diverse states of the "adaptation continuum". Endurance training of sufficient volume and intensity results in an increased whole body maximal O 2 uptake and shifts in substrate utilization from carbohydrate-to lipid-based fuels, largely as a result of an expanded mitochondrial density and volume (25). Such changes are brought about by the coordinated coexpression of both the nuclear and mitochondrial genomes that, together, ensure proper assembly and expansion of the mitochondrial reticulum (2). Thus endurance training-induced adaptations culminate in mitochondrial biogenesis, an organelle capable of improved ATP provision (25), and a concomitant enhancement of endurance capacity (23). In contrast, resistance exercise comprising high-intensity, low-volume loading results in an increased cross-sectional area of the trained musculature, which is mainly due to an increase in m...