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Hensel N, Brickwedde H, Tsaknakis K, Grages A, Braunschweig L, Lüders KA, Lorenz HM, Lippross S, Walter LM, Tavassol F, Lienenklaus S, Neunaber C, Claus P, Hell AK. Altered bone development with impaired cartilage formation precedes neuromuscular symptoms in spinal muscular atrophy. Hum Mol Genet 2021; 29:2662-2673. [PMID: 32644125 DOI: 10.1093/hmg/ddaa145] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Revised: 07/06/2020] [Accepted: 07/06/2020] [Indexed: 01/04/2023] Open
Abstract
Spinal muscular atrophy (SMA) is a fatal neurodegenerative disease of newborns and children caused by mutations or deletions of the survival of motoneuron gene 1 resulting in low levels of the SMN protein. While neuromuscular degeneration is the cardinal symptom of the disease, the reduction of the ubiquitously expressed SMN additionally elicits non-motoneuron symptoms. Impaired bone development is a key feature of SMA, but it is yet unknown whether this is an indirect functional consequence of muscle weakness or caused by bone-intrinsic mechanisms. Therefore, we radiologically examined SMA patients in a prospective, non-randomized cohort study characterizing bone size and bone mineral density (BMD) and performed equivalent measurements in pre-symptomatic SMA mice. BMD as well as lumbar vertebral body size were significantly reduced in SMA patients. This growth defect but not BMD reduction was confirmed in SMA mice by μCT before the onset of neuromuscular symptoms indicating that it is at least partially independent of neuromuscular degeneration. Interestingly, the number of chondroblasts in the hypertrophic zone of the growth plate was significantly reduced. This was underlined by RNAseq and expression data from developing SMA mice vertebral bodies, which revealed molecular changes related to cell division and cartilage remodeling. Together, these findings suggest a bone intrinsic defect in SMA. This phenotype may not be rescued by novel drugs that enhance SMN levels in the central nervous system only.
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Affiliation(s)
- Niko Hensel
- Institute of Neuroanatomy and Cell Biology, Hannover Medical School, Hannover, Germany.,Center for Systems Neurosciences (ZSN), Hannover, Germany
| | - Hermann Brickwedde
- Institute of Neuroanatomy and Cell Biology, Hannover Medical School, Hannover, Germany
| | - Konstantinos Tsaknakis
- Pediatric Orthopedics, Department of Trauma, Orthopedic and Plastic Surgery, University Medical Center Goettingen, Goettingen, Germany
| | - Antonia Grages
- Pediatric Orthopedics, Department of Trauma, Orthopedic and Plastic Surgery, University Medical Center Goettingen, Goettingen, Germany
| | - Lena Braunschweig
- Pediatric Orthopedics, Department of Trauma, Orthopedic and Plastic Surgery, University Medical Center Goettingen, Goettingen, Germany
| | - Katja A Lüders
- Pediatric Orthopedics, Department of Trauma, Orthopedic and Plastic Surgery, University Medical Center Goettingen, Goettingen, Germany
| | - Heiko M Lorenz
- Pediatric Orthopedics, Department of Trauma, Orthopedic and Plastic Surgery, University Medical Center Goettingen, Goettingen, Germany
| | - Sebastian Lippross
- Pediatric Orthopedics, Department of Trauma, Orthopedic and Plastic Surgery, University Medical Center Goettingen, Goettingen, Germany
| | - Lisa M Walter
- Institute of Neuroanatomy and Cell Biology, Hannover Medical School, Hannover, Germany.,Center for Systems Neurosciences (ZSN), Hannover, Germany
| | - Frank Tavassol
- Department of Oral and Maxillofacial Surgery, Hannover Medical School, Hannover, Germany
| | - Stefan Lienenklaus
- Institute for Laboratory Animal Science and Central Animal Facility, Hannover Medical School, Hannover, Germany
| | | | - Peter Claus
- Institute of Neuroanatomy and Cell Biology, Hannover Medical School, Hannover, Germany.,Center for Systems Neurosciences (ZSN), Hannover, Germany
| | - Anna K Hell
- Pediatric Orthopedics, Department of Trauma, Orthopedic and Plastic Surgery, University Medical Center Goettingen, Goettingen, Germany
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