Written by - Sun Junjie Responsible Editor - Wang Sizhen Editor - Yang Binwei spinal muscular atrophy (SMA) is a common fatal genetic disorder in children, the most important pathological features are motor neuron degeneration in the anterior corner of the spinal cord and neuromuscular joint necrosis
.

SMA is caused
by mutations or deletions in the motor neuron survival 1 gene (SMN1) that do not encode the SMN protein.

There are also one or several copies of the backup gene for SMN1 in humans, called motor neuron survival 2 (SMN2), which produces only a small amount of the functional SMN protein due to incorrect splicing, but this does not compensate for the absence of SMN1 [1].


Direct supplementation with SMN protein or splicing of corrected SMN2 is the main method
of treating SMA.

SMN is a versatile butler protein
.

Its most well-known function is to form a complex with the Gemin protein to participate in splicoidal assembly
.

Another important function of SMN is to participate in messenger RNA transport in motor neuron axons
.

To date, however, no downstream molecules of SMN have been found that cause the death of motor neurons
due to splicing errors or altered localization.

Studies have shown that motor neurons in SMA are not defective in cell autonomy, and there are three important pieces of evidence: 1) Specifically deleting SMNs in healthy motor neurons can only cause limited movement disorders rather than complete SMA; 2) Specific supplementation of SMN to motor neurons of SMA does not completely alleviate the condition; 3) Saving the expression of SMN in non-neuronal cells can alleviate the condition of SMA and greatly prolong lifespan [2-4].

Although fibroblasts are an important part of the vasculature, there has not been much
research on their precise function.

Interestingly, recent studies have shown that fibroblasts play a role other than support cells in neurodegenerative diseases [7-9
].

This suggests that fibroblasts may have unknown important functions, and their lesions may be a typical feature
of neurodegenerative diseases.

Why fibroblasts are more susceptible to fibroblasts in SMA and other neurodegenerative diseases – is also worth exploring
in the future.

Together, the study not only provides a single-cell atlas of the first SMA, but also reveals a new mechanism
of involuntary degeneration of motor neuronal cells.

Sun Junjie, Key Laboratory of Neuroregeneration, Nantong University, https://doi.

[2] G.

[3] R.

[4] Y.

[5] E.

[6] A.

[7] Yang AC, Vest RT, Kern F, Lee DP, Agam M, Maat CA, et al.

[8] Manberg A, Skene N, Sanders F, Trusohamn M, Remnestal J, Szczepinska A, et al.

[9] C.
E.
Dorrier, H.
E.
Jones, L.
Pintaric, J.
A.
Siegenthaler, and R.
Daneman, Emerging roles for CNS fibroblasts in health, injury and disease.
Nat Rev Neurosci 23 (2022) 23-34.

End of article