Calpain 3 Is Important for Muscle Regeneration

Evidence from Patients with Limb Girdle Muscular Dystrophies

Simon Hauerslev; Marie-Louise Sveen; Morten Duno; Corrado Angelini; John Vissing; Thomas O Krag

BMC Musculoskelet Disord. 2012;13(43)

Abstract and Introduction

Abstract

Background Limb girdle muscular dystrophy (LGMD) type 2A is caused by mutations in the CAPN3 gene and complete lack of functional calpain 3 leads to the most severe muscle wasting. Calpain 3 is suggested to be involved in maturation of contractile elements after muscle degeneration. The aim of this study was to investigate how mutations in the four functional domains of calpain 3 affect muscle regeneration.
Methods We studied muscle regeneration in 22 patients with LGMD2A with calpain 3 deficiency, in five patients with LGMD2I, with a secondary reduction in calpain 3, and in five patients with Becker muscular dystrophy (BMD) with normal calpain 3 levels. Regeneration was assessed by using the developmental markers neonatal myosin heavy chain (nMHC), vimentin, MyoD and myogenin and counting internally nucleated fibers.
Results We found that the recent regeneration as determined by the number of nMHC/vimentin-positive fibers was greatly diminished in severely affected LGMD2A patients compared to similarly affected patients with LGMD2I and BMD. Whorled fibers, a sign of aberrant regeneration, was highly elevated in patients with a complete lack of calpain 3 compared to patients with residual calpain 3. Regeneration is not affected by location of the mutation in the CAPN3 gene.
Conclusions Our findings suggest that calpain 3 is needed for the regenerative process probably during sarcomere remodeling as the complete lack of functional calpain 3 leads to the most severe phenotypes.

1 2 3 4 5 6

Next Section

Abstract and Introduction
Background
Methods
Results
Discussion
Conclusions
References

Table 1. Genotype, muscle strength, pathological severity, calpain 3 expression and recently regenerating fibers in patients with limb-girdle muscular dystrophy type 2A and 2I, and Becker muscular dystrophy
Patient	Age/onset	Clinical diagnosis	Mutation	Effect of mutation	GMW	Biopsy origin (force% or MRC)	CK	Calpain 3 WB	nMHC/Vimentin+	Pathological severity	NF	WF	N_fibers
1M	30/n.d	LGMD2A	p.S48N/p.R748X	Missense/null	0	Q.f. (n.d.)	2400	≈ 10	0.0%	3	0.0%	0.0%	332
2M	22/11	LGMD2A	p.I178T homoz.	Missense	3	Q.f. (n.d.)	2100	≈ 0	12.9%	3	0.6%	0.4%	1236
3M	36/35	LGMD2A	p.T184M/c.259–260insT	Missense/null	2	Q.f. (3+)	3000	≈ 100	0.4%	3	0.0%	0.0%	468
4F	38/28	LGMD2A	p.T192I/p.Y537X	Missense/null	4	Q.f. (n.d.)	900	≈ 100	0.2%	3	0.0%	0.0%	2804
5M	61/n.d.	LGMD2A	c.643–663del homoz.	In-frame deletion	3	Q.f. (41%)	700	≈ 20	0.2%	3	0.4%	0.0%	497
6M	41/40	LGMD2A	c.643–663del homoz.	In-frame deletion	3	Q.f. (57%)	600	≈ 30	2.5%	3	0.3%	0.0%	667
7M	36/32	LGMD2A	p.R289W/p.I661X	Missense/null	3	Q.f. (84%)	5000	≈ 15	0.2%	3	0.7%	0.0%	601
8M	17/16	LGMD2A	p.V354G homoz.	Missense	4	Q.f. (4)	4600	n.d	17.8%	2	0.4%	0.0%	765
9M	30/30	LGMD2A	p.W373R homoz.	Missense	4	Q.f. (74%)	1400	≈ 10	11.3%	3	0.2%	0.2%	663
10M	38/22	LGMD2A	p.R437G homoz.	Missense	6	T.a. (25%)	600	≈ 5	4.6%	3	0.3%	0.4%	1142
11M	43/22	LGMD2A	p.G446S homoz.	Missense	9	Q.f. (36%)	700	≈ 15	2.9%	1	1.4%	0.7%	1171
12F	46/24	LGMD2A	p.R448H/c.1992+1G>T	Missense/null	5	T.b. (n.d.)	500	≈ 0	3.3%	2	0.1%	0.0%	2195
13F	23/15	LGMD2A	p.N449H homoz.	Missense	4	Q.f. (4+)	2700	≈ 5	4.8%	2	0.3%	0.0%	1451
14M	44/36	LGMD2A	p.R461C homoz.	Missense	3	Q.f. (49%)	4900	≈ 55	0.3%	3	0.2%	0.0%	1415
15F	49/47	LGMD2A	p.R490Q homoz.	Missense	5	T.b. (n.d.)	1000	≈ 100	0.5%	3	0.0%	0.0%	811
16M	16/16	LGMD2A	p.R490Q homoz.	Missense	0	Q.f. (n.d.)	n.d.	≈ 100	4.7%	3	0.0%	0.0%	2402
17M	38/19	LGMD2A	p.R748Q homoz.	Missense	4	T.b. (4)	n.d.	≈ 0	4.6%	2	0.1%	0.0%	2202
18F	20/12	LGMD2A	p.I777T/c.550delA	Missense/null	6	B.b. (3)	2300	≈ 0	17.6%	2	0.2%	0.0%	873
19F	46/22	LGMD2A	p.A798E homoz.	Missense	6	Q.f. (90%)	1600	≈ 30	2.8%	3	0.6%	0.0%	360
20M	38/9	LGMD2A	c,1800+2T>C homoz.	Null	9	T.a. (14%)	200	0	0.3%	1	1.9%	3.1%	483
21M	68/29	LGMD2A	c.380–13T>A homoz.	Null	9	Q.f. (0%)	200	0	0.8%	1	2.7%	7.8%	257
22M	38/15	LGMD2A	p.E285X homoz.	Null	9	T.a. (7%)	n.d.	0	0.0%	1	1.7%	6.0%	351
23–27	27 ± 12/6 ± 4	LGMD2I	Various	Missense	9.0 ± 0.0	T.a. 6 ± 6%	700 ± 700	55 ± 20	22.7 ± 12.7%	1.0 ± 0.0	1.7 ± 1.5%	3.4 ± 3.1%	781 ± 372
28–32	34 ± 12/25 ± 11	BMD	Various	Missense	8.6 ± 0.5	T.a. 9 ± 9%	4700 ± 7300	95 ± 5	20.3. ± 13.8%	1.8 ± 0.7	0.8 ± 0.7%	0.7 ± 0.9%	499 ± 402

M/F = male/female; Age = age when biopsy was taken; n.d. = not determined; LGMD2A = limb-girdle muscular dystrophy type 2A; LGMD2I = limb-girdle muscular dystrophy type 2I; BMD = Becker muscular dystrophy; Mutations in introns are marked in italic; GMW = modified Gardner-Medwin-Walton scale; Q.f. = Quadriceps femoris; T.b. = Triceps brachii; B.b. = Biceps brachii; T.a. = Tibialis anterior; CK = creatine kinase; WB = presence of calpain 3 (94 + 60 bands) in western blot in percent of normal; nMHC/Vimentin + = Regenerating fibers expressing neonatal myosin heavy chain and vimentin; Pathological severity: (3 = mild), (2 = moderate) and (1 = severe); NF = Necrotic fibers; WF = Whorled fibers; N_fibers = number of fibers analyzed in each section

Comments

Commenting is limited to medical professionals. To comment please Log-in.

Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.