Stable Knockdown of Genes Encoding Extracellular Matrix Proteins in the C2C12 Myoblast Cell Line Using Small-Hairpin (sh)RNA

Summary

We provide a protocol to stably knock down genes encoding extracellular matrix (ECM) proteins in C2C12 myoblasts using small-hairpin (sh) RNA. Targeting ADAMTSL2 as an example, we describe the methods for the validation of the knockdown efficiency on the mRNA, protein, and cellular level during C2C12 myoblast to myotube differentiation.

Abstract

Extracellular matrix (ECM) proteins are crucial for skeletal muscle development and homeostasis. The stable knockdown of genes coding for ECM proteins in C2C12 myoblasts can be applied to study the role of these proteins in skeletal muscle development. Here, we describe a protocol to deplete the ECM protein ADAMTSL2 as an example, using small-hairpin (sh) RNA in C2C12 cells. Following transfection of shRNA plasmids, stable cells were batch-selected using puromycin. We further describe the maintenance of these cell lines and the phenotypic analysis via mRNA expression, protein expression, and C2C12 differentiation. The advantages of the method are the relatively fast generation of stable C2C12 knockdown cells and the reliable differentiation of C2C12 cells into multinucleated myotubes upon depletion of serum in the cell culture medium. Differentiation of C2C12 cells can be monitored by bright field microscopy and by measuring the expression levels of canonical marker genes, such as MyoD, myogenin, or myosin heavy chain (MyHC) indicating the progression of C2C12 myoblast differentiation into myotubes. In contrast to the transient knockdown of genes with small-interfering (si) RNA, genes that are expressed later during C2C12 differentiation or during myotube maturation can be targeted more efficiently by generating C2C12 cells that stably express shRNA. Limitations of the method are a variability in the knockdown efficiencies, depending on the specific shRNA that may be overcome by using gene knockout strategies based on CRISPR/Cas9, as well as potential off-target effects of the shRNA that should be considered.

Introduction

Extracellular matrix (ECM) proteins provide structural support for all tissues, mediate cell-cell communication, and determine cell fate. The formation and dynamic remodeling of ECM is thus critical to maintain tissue and organ homeostasis^1,2. Pathological variants in several genes coding for ECM proteins give rise to musculoskeletal disorders with phenotypes ranging from muscular dystrophies to pseudomouscular build^3,4. For example, pathogenic variants in ADAMTSL2 cause the extremely rare musculoskeletal disorder geleophysic dysplasia, which ....

Protocol

1. Preparing the shRNA Plasmid DNA from Escherichia coli

1. Generation of clonal bacterial colonies carrying the shRNA plasmids
   1. Obtain glycerol stocks of E. coli carrying target-specific shRNA plasmids and a control plasmid from commercial sources (Table of Materials).
      NOTE: Three different shRNA plasmids were used, targeting different regions of the murine Adamtsl2 mRNA. One shRNA was selected to target the 3'-untranslated region (3'UTR) of Adamtsl2 to facilitate rescue experiments with expression plasmids encoding recombinant full-length ADAMTSL2 or individual ADAMTSL2 protein ....

Results

Selection of puromycin-resistant C2C12 can be achieved in 10−14 days after transfection due to efficient elimination of non-resistant, i.e., untransfected cells (Figure 1B). Typically, more than 80% of the cells detach from the cell culture dish and these cells are removed during routine cell maintenance. Puromycin-resistant C2C12 cells expressing the control (scrambled) shRNA retain the spindle-shape, elongated cell morphology at low cell density and the capability to diffe.......

Discussion

We describe here a protocol for the stable knockdown of ECM proteins in C2C12 myoblasts and for phenotypic analysis of the differentiation of C2C12 myoblasts into myotubes. Several factors determine the outcome of the experiment and need to be considered carefully. Maintaining C2C12 cells in the proliferating phase is a critical step to keep the C2C12 cells in the myoblast precursor state. Retaining the capability of C2C12 cells to consistently differentiate into myotubes depends on i) the passage number of the cells, ii.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Acetone	Fisher Chemical	191784
Agar	Fisher Bioreagents	BP1423
Ampicillin	Fisher Bioreagents	BP1760-5
Automated cell counter Countesse II	Invitrogen	A27977
Bradford Reagent	Thermo Scientific	P4205987
C2C12 cells	ATCC	CRL-1772
Chamber slides	Invitrogen	C10283
Chloroform	Fisher Chemical	183172
DMEM	GIBCO	11965-092
DMSO	Fisher Bioreagents	BP231-100
DNase I (Amplification Grade)	Invitrogen	18068015
Fetal bovine serum	VWR	97068-085
GAPDH	EMD Millipore	MAB374
Glycine	VWR Life Sciences	19C2656013
Goat-anti-mouse secondary antibody (IRDYE 800CW)	Li-Cor	C90130-02
Goat-anti mouse secondary antibody (Rhodamine-red)	Jackson Immune Research	133389
HCl	Fisher Chemical	A144S
Incubator (Shaker)	Denville Scientific Corporation	1704N205BC105
Mercaptoethanol	Amresco, VWR Life Sciences	2707C122
Midiprep plasmid extraction kit	Qiagen	12643
Myosin 4 (myosin heavy chain)	Invitrogen	14-6503-82
Mounting medium	Invitrogen	2086310
NaCl	VWR Life Sciences	241
non-ionic surfactant/detergent	VWR Life Sciences	18D1856500
Paraformaldehyde	MP	199983
PBS	Fisher Bioreagents	BP399-4
PEI	Polysciences	23966-1
Penicillin/streptomycin antibiotics	GIBCO	15140-122
Petridishes	Corning	353003
Polypropylene tubes	Fisherbrand	149569C
Protease inhibitor cocktail tablets	Roche	33576300
Puromycin	Fisher Scientific	BP2956100
PCR (Real Time)	Applied Biosystems	4359284
Reaction tubes	Eppendorf	22364111
Reverse Transcription Master Mix	Applied Biosystems	4368814
RIPA buffer	Thermo Scientific	TK274910
sh control plasmid	Sigma-Aldrich	07201820MN
sh 3086 plasmid	Sigma-Aldrich	TRCN0000092578
sh 972 plasmid	Sigma-Aldrich	TRCN0000092579
sh 1977 plasmid	Sigma-Aldrich	TRCN0000092582
Spectrophotometer (Nanodrop)	Thermo Scientific	NanoDrop One C
SYBR Green Reagent Master Mix	Applied Biosystems	743566
Trichloroacetic acid	Acros Organics	30145369
Trizol reagent	Ambion	254707
Trypan blue	GIBCO	15250-061
Tryptone	Fisher Bioreagents	BP1421
Trypsin EDTA 0.25%	Gibco-Life Technology Corporation	2085459
Water (DEPC treated and nuclease free)	Fisher Bioreagents	186163
Western blotting apparatus	Biorad	Mini Protean Tetra Cell
Yeast extract	Fisher Bioreagents	BP1422