The Author(s) BMC Medical Genetics 2016, 17(Suppl 1):68
DOI 10.1186/s12881-016-0330-2

REVIEW

Open Access

Identification of novel genetic variations
affecting osteoarthritis patients
Mamdooh Abdullah Gari1,2,6*, Mohammed AlKaff1,4, Haneen S. Alsehli1,2, Ashraf Dallol2, Abdullah Gari2,3,
Muhammad Abu-Elmagd5, Roaa Kadam5, Mohammed F. Abuzinadah2,6, Mazin Gari2, Adel M. Abuzenadah2,6,Kalamegam Gauthaman1,5, Heba Alkhatabi5,6 and Mohammed M. Abbas1,4
From 3rd International Genomic Medicine Conference
Jeddah, Saudi Arabia. 30 November - 3 December 2015

Abstract
Background: Osteoarthritis (OA) is a progressive joint disease characterized by gradual degradation of extracellularmatrix (ECM) components in the cartilage and bone. The ECM of cartilage is a highly specified structure that ismainly composed of type II collagen and provides tensile strength to the tissue via aggrecan and proteoglycans.
However, changes in the ECM composition and structure can lead to loss of collagen type II and network integrity.
Several risk factors have been correlated with OA including age, genetic predisposition, hereditary factors, obesity,
mechanical injuries, and joint trauma. Certain genetic association studies have identified several genes associatedwith OA using genome-wide association studies (GWASs).
Results: We identified several novel genetic variants affecting genes that function in several candidate causative
pathways including immune responses, inflammatory and cartilage degradation such as SELP, SPN, and COL6A6.
Conclusions: The approach of whole-exome sequencing can be a promising method to identify genetic mutations
that can influence the OA disease.
Keywords: Osteoarthritis, Whole-exome sequencing, Single nucleotide variants

Background
Osteoarthritis (OA) of the knee, which is characterized
by gradual degradation of articular cartilage and subchondral bone, is the most common joint disease occurring worldwide [1, 2]. Approximately 27 million
individuals in the USA alone are estimated to be diagnosed with OA which affects about 10% of adults overage 55 years old [2, 3]. Various risk factors have been associated with OA including genetic predisposition, obesity, gender, mechanical injuries, physical workload, andjoint trauma. However, age is the most common factor
and affects especially the weight bearing joints, which isoften under mechanical stress [4]. The progression of* Correspondence: mgari@kau.edu.sa
1
Sheikh Salem Bin Mahfouz Scientific Chair for Treatment of Osteoarthritis by
Stem Cells, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia
2
Center of Innovation in Personalized Medicine, King Abdulaziz University,
Jeddah, Kingdom of Saudi Arabia
Full list of author information is available at the end of the article

OA is a consequence of mechanical, biological, biochemical, and molecular factor interactions. What correlation?
This correlation can disturb the normal series of synthesis and degradation of articular cartilage chondrocytes
and extracellular matrix (ECM) components, and subchondral bone [5, 6]. In normal cartilage ECM there is abalance between synthesis and degradation that sustain
dynamic equilibrium which can be disrupted if microenvironment changes in the ECM composition andstructure result in type II collagen loss [7].
Inflammatory stimuli are associated with cartilage
ECM changes in OA and play an essential role in thepathogenesis of synovium inflammation and cartilage degeneration through inducing the catabolic activities ofchondrocytes [8, 9]. These Inflammatory factors and cytokines include interleukins family (IL) (IL-1, IL-4, IL-6,
IL-17, IL-18), and tumor necrosis factor- ∝ (TNF- ∝)[10–14]. For instance, the inflammatory cytokine IL-1β© 2016 The Author(s). Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0
International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, andreproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to
the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

The Author(s) BMC Medical Genetics 2016, 17(Suppl 1):68

is highly expressed in OA stimulating the expression of
matrix degradation enzymes including MMP-1, MMP-3,
and MMP-13 in chondrocytes and inhibiting ECM synthesis by decreasing the expression SOX9 [15, 16]. This
response ultimately decreases the expression of collagentype II and aggrecan in articular cartilage that lead to reducing the production of chondrogenic ECM [7].
The genetic predisposition to OA is not fully understood. A number of family studies have investigated thegenetic nature of OA. Familial mutations were identified
in the type II collagen gene (COL2A1) [17]. Mutations
affecting collagen IX gene, and COL9A1 have been
linked to OA of the hip [18]. Recently, various genetic
association studies have identified several genes associated with OA using genome-wide association studies(GWASs). These genes include GDF5, DUS4L, Ch7q22,
MCF2L, and GNL3 [19–22]. However, the genetic association between single nucleotide polymorphisms and
OA disease remain controversial.
In this study, a pilot whole-exome sequencing analysis
was performed on osteoarthritis cases in order to identify
candidate gene mutations associated with OA in Saudi
Arabia.

Methods
Patients

Peripheral blood was obtained from five end-stage osteoarthritis patients with age range of 46–70 years old. The
collection of these samples were approved by the King
Abdulaziz University Hospital’s ethical committee (No.11–
557). Informed consent was collected from all donors prior
to participation in this study.

Page 10 of 23

Table 1 Primers used for validation of the single nucleotide
variations identified by whole-exome sequencing
Gene

Forward primer (5′→3′)

Reverse primer (5′→3′)

SELP

CCTGTGTAACACAATGCGCTACAGCTCCTACTACTG

FIGNL1ATGGTAGCAATGTCAGCAGGAAGATCGTATCCTAGTGG

SPN

CTCGTGCTGAGCAGAGGCCATCCTCACTGGCCACCAG

USP36

CTCGTGCTGAGCAGAGGCCTCACTGGCCACCAGTGG

TNRC6B

TCTGGCAGAGAACAGGCTCCACCTGTTATTGTTGTCCHSPG2GACTCTGCTATGCCATGTCCACAGGTGGTCAGCGACACSUSD5AGGTGTCTGCTTGACAGTG

CTAGTTACTCCTGATCAGCITGA8GGAAGGCTAATAACGATCAG

GGTTAGTAACGTGTGTTCTCPXNCATCCAAGAGACTCTCCAC

CCATCTGCTGACCTCTAGNLRP6AGCAACTGGAGCTTCGTG

GTGGCGCTCGATGTCGCGC

COL2A1

CTTAGTCCAGAGACTGCG

GGCCTGACAGGTCAGCTG

COL6A6

CATCGGTGCTGCACTCAG

CTGTGGTACAGATGTTGCGGAS6GGCACGCAGCAGATGCAG

CCCAGGCTGGTAGCTGAG

conditions were performed at one denaturation cycle at
95o C for 15 min followed by 35 cycles of denaturation
at 95o C for 30 s, and annealing at 52o C for 30 s and extension at 72o C for 30 s. The final step was done at 72o
C for 10 min. To perform Sanger sequencing, purification of PCR products using ethanol precipitation wererequired prior to the cycle sequencing reaction. Purified
PCR products were labeled with BigDye Terminator kit
v3.1 (ABI Biosystem, USA) for cycle sequencing according to the manufacture procedure. After the second
purification for the PCR products, the sequencing analysis was performed on the automated sequencer from
Applied Biosystems 3500 DNA Analyzer.

Whole- exome sequencing

Genomic DNA was extracted from peripheral blood
samples of five OA cases using QIAamp DNA bloodmini kit according to the manufacture procedure (Qiagen
Inc, USA). Briefly, three micrograms of genomic DNA
were fragmented using the Covaris S2 system. Exome capture was performed using the Agilent’s SureSelect WholeExome Enrichment kit (v4). Fragment libraries wereprepared from the captured exomes for sequencing on the
SOLiD 5500 platform (Applied Biosystems). Fragments
were sequenced in single reads of 50 bp. Reads werealigned to the UCSC hg19 reference sequence of the human genome using the LifeScope analysis pipeline which
was also utilized for variants identification and annotation.
PCR amplification and sanger sequencing

DNA was amplified using custom oligonucleotides
primers listed in Table 1. Polymerase chain reaction reactions (PCR) was performed to amplify the selectedprimers. The PCR reactions were conducted using Go
Taq Green Master Mix (Promega, USA). The reactions

Results
Whole-exome sequencing of 5 OA patients revealed several
novel mutations that are predicted to be damaging to protein function (SIFT). Identified variants were prioritized according to their ontology grouping in ECM and/or
inflammation (Table 2). A novel c.381G > T, p.Asn127Lys
mutation in the gene selectin P (SELP) has not been reported in dbSNP, 1000 Genomes project or the ExAC project. We have validated this mutation by Sanger sequencing
and confirmed its existence in the heterozygous state in
one patient (Fig. 1). Another novel mutation was identified
in the collagen type VI alpha 6 (COL6A6) gene in another
OA patient. This heterozygous c.2263T > C, p.Ile1137Thr
change was also validated by Sanger sequencing.
Other single nucleotide variants were identified that
had no minor allele frequency reported by dbSNP.
However, they were also found by the ExAC project
albeit at a very low frequency (Fig. 1). These genes
were identified that impact cartilages extracellularmatrix (ECM) organization and cartilage development

The Author(s) BMC Medical Genetics 2016, 17(Suppl 1):68

Page 11 of 23

Table 2 Single nucleotide variants identified in our whole-exome screen of OA patients and validated by Sanger sequencing
Gene

Chromosome position

AA change

Nucleotide change

Protein ID

dbSNP

HSPG2

1,22154535,G,A

p.Arg4174Cys

c.4391C > T

ENSP00000363827

rs199899258

0.00005066

SUSD5

3,33194727,G,A

p.Thr466Met

c.629C > T

ENSP00000308727

rs377664152

0.00009122

ITGA8

10,15628601,G,A

p.Ala785Val

c.1063C > T

ENSP00000367316

rs371802080

0.0000248

PXN

12,120660505,T,C

p.Tyr181Cys

c.605A > G

ENSP00000267257

rs371118243

0.0001199

COL2A1

12,48371204,G,A

p.Arg1058Cys

c.1487C > T

ENSP00000369889

rs148350640

0.00002493

COL6A63,130293232,T,C

p.Ile1137Thr

c.2263T > C

ENSP00000351310

rs200274210

0.006855

FIGNL1

7,50513244,A,G

p.Met581Thr

c.674T > C

ENSP00000349356

rs200453649

0.000173

USP36

17,76803235,T,C

p.Arg631Glyc.1123A > G

ENSP00000441214

rs112843316

0.000082

SPN

16,29676061,C,T

p.Arg338Cys

c.400C > T

ENSP00000353238

rs200681097

0.000485

TNRC6B

22,40661502,G,T

p.Gly423Val

c.1833G > T

ENSP00000401946

rs201057205

0.0003241

SELP

1,169586366,G,T

p.Asn127Lys

c.381G > T

ENSP00000263686

NA

NA

NLRP6

11,281256,G,T

p.Ala508Ser

c.892G > T

ENSP00000309767

rs373174851

0.000101

GAS6

13,114535300,G,A

p.Pro415Leu

c.721C > T

ENSP00000349962

NA0.0000353

including heparan sulfate proteoglycan2 (HSPG2), sushi
domain containing 5 (SUSD5), integrin subunit alpha 8(ITGA8), paxillin (PXN), collagen type II alpha 1(COL2A1), and fidgetin-like 1 (FIGNL1). Moreover, ourresults revealed some mutations associated in the inflammatory response and immune response such as pyrin domain containing 6 (NLRP6) and growth arrest specific 6(GAS6); ubiquitin specific peptidase 36 (UPS36), sialophorin (SPN), and trinucleotide repeat containing 6B(TNRC6B) respectively (Table 2).

Discussion
To identify the predisposition genetic factors and the association of these candidate genes with the disease, we
conducted a pilot whole-exome sequencing on 5 OA patients from Saudi Arabia. The result of the exome sequence analysis identified several nucleotide variants

ExAC frequency

affecting candidate genes that could likely contribute in
OA susceptibility and involved in crucial pathways including cartilage degradation and development, inflammatory, and immune response [5].
The finding of mutations in these genes functionally interrelated to cartilage ECM organization and cartilage signaling pathway may have functional consequences. One of
the identified mutations in this study is the p.Arg4174Cys
mutation found in the HSPG2 gene. This gene plays multiple roles in the extracellular matrix organization involvedin cartilage development, endochondral bone morphogenesis, and chondroitin sulfate metabolic process. Additionally, it is responsible for glycosaminoglycan (GAG)
biosynthetic and catabolic process that maintains the expression and aggregation of mature chondrogenic markers[23]. SUSD5 harbors the p.Thr466Met mutation in one OA
patient from our cohort. This gene influences theFig. 1 Selected chromatograms showing the Sanger confirmation of identified variants in our samples

The Author(s) BMC Medical Genetics 2016, 17(Suppl 1):68

hyaluronic acid binding, a core component in articular cartilage [24]. Another mutation was identified is thep.Ala785Val mutation in ITGA8, and the p.Tyr181Cys mutation in PXN gene. Both ITGA8 and PXN genes are important in cellular matrix adhesion, ECM organization, andtransforming growth factor beta receptor regulation [25,26]. Most importantly, SNPs variants in cartilage related
genes that impacts cartilage development, cartilage condensation, ECM and collagen fibril organization, and collagencatabolic process has been associated in our OA patients.
That includes the p.Arg1058Cys mutation in COL2A1, andthe p.Ile1137Thr mutation in COL6A6. In addition, the results of this study showed the p.Met581Thr mutation in
FIGNL1 gene; a gene that influences the regulatory role inosteoblast proliferation and differentiation [27].
The result of this exome analysis revealed other mutations related to the inflammatory response such as NLRP6
and GAS6; and immune response such as USP36, SPN,
and TNRC6B. The identified mutation in UPS36 gene isp.Arg631Gly. This gene is a known member of the ubiquitin specific protease family that regulates the immune signaling pathway [28]. The p.Arg338Cys mutation in SPN
was also identified in our patients, and the influence of
this gene can affect cellular defense responses and theregulation of the tumor necrosis factor (TNF) pathway[29]. The mutation found in TNRC6B gene is p.Gly423Val; this gene not only act in the innate immune response,
but also regulates fibroblast growth factor receptor signaling pathway [30]. Furthermore, the results showed someother mutations involved in the inflammatory response.
Interestingly, we identified a novel SNV variation in the
SELP, p.Asn127Lys, which has not been reported previously. The function of SELP is to stimulate leukocytes adhesion in the site of injury, which could explain thepresence of inflammatory markers IL family, and TNF in
OA patients [31]. The p.Ala508Ser mutation in NLRP6
gene, and the p.Pro415Leu mutation in the GAS6 gene
were identified in our screen; both genes regulates the inflammatory response [32, 33]. However, GAS6 specificallyregulates tumor necrosis factor-mediated signaling pathway and macrophage cytokine production [33].

Conclusions
OA is a progressive joint disease characterized by gradual degradation of (ECM) components in the cartilage
and bone. Several risk factors have been associated with
OA such as genetic predisposition and molecular factors.
In this study, a pilot whole-exome sequencing was performed and we identified several genes candidate genes
associated with OA in Saudi Arabia that function invarious causative pathways including immune response,
inflammatory and cartilage degradation. Despite thesmall sample size of this group, a hypothesis could beformulated that states the importance of personalized

Page 12 of 23

genetic screening of OA patients in order to understandthe individual’s genetic makeup potentially responsible
for susceptibility towards OA.
Abbreviations
OA: Osteoarthritis; ECM: Extracellular matrix; SNPs: Single nucleotide
polymorphisms
Acknowledgment
We would like to acknowledge the financial support provided by the Sheikh
Salem Bin Mahfouz Scientific Chair for Treatment of Osteoarthritis by StemCells. The Center of Innovation in Personalized Medicine (CIPM), Stem Cell
Lab at Center of Excellence for Genomic Medicine Research and the Orthopedics
Stem Cell Research Lab (CEGMR) at King Abdulaziz University Hospital for
supporting this study.
Declaration
This article has been published as part of BMC Medical Genetics Volume 17
Supplement 1, 2016: Proceedings of the 3rd International Genomic Medicine
Conference: medical genetics. The full contents of the supplement areavailable online at http://bmcmedgenet.biomedcentral.com/articles/
supplements/volume-17-supplement-1.
Funding
This study was funded by the Sheikh Salem Bin Mahfouz Scientific Chair for
Treatment of Osteoarthritis by Stem Cells. Publication fees for this article arepaid by the Center of Excellence in Genomic Medicine Research (CEGMR),
King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia.
Availability of data and materials
Not applicable.
Authors’ contributions
MAG, AMA, MAE, AD and MMA participated in the study design. MA, MAG,AG, MG and HSA performed data collection, DNA extraction and sequencing
studies. KG, HA, RK, MAE and AD analyzed data, interpreted the results anddrafted the manuscript. MAG, AMA, MMA, and MFA participated in criticalreview, editing and finalization of manuscript. All authors read and approved
the final manuscript.
Competing interests
The authors declare that they have no competing interests.
Consent for publication
Not applicable.
Ethics approval and consent to participate
This study was approved by the Research Committee of the Biomedical
Ethics Unit, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi
Arabia. Participants in the study provided their consent prior to sample
collection.
Author details
1
Sheikh Salem Bin Mahfouz Scientific Chair for Treatment of Osteoarthritis by
Stem Cells, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia.
2
Center of Innovation in Personalized Medicine, King Abdulaziz University,
Jeddah, Kingdom of Saudi Arabia. 3Department of Hematology, Faculty of
Medicine, King Abdulaziz University Hospital, King Abdulaziz University,
Jeddah, Kingdom of Saudi Arabia. 4Department of Orthopedic Surgery,
Faculty of Medicine, King Abdulaziz University, Jeddah, Kingdom of Saudi
Arabia. 5Centre of Excellence in Genomic Medicine Research, King Abdulaziz
University, Jeddah, Kingdom of Saudi Arabia. 6Department of Medical
Laboratory Technology, Faculty of Applied Medical Sciences, King Abdulaziz
University, P.O. Box 80216, Jeddah 21589, Kingdom of Saudi Arabia.
Published: 10 October 2016
References
1. Lane NE, Brandt K, Hawker G, Peeva E, Schreyer E, Tsuji W, Hochberg MC.
OARSI-FDA initiative: defining the disease state of osteoarthritis. Osteoarthr
Cartil. 2011;19(5):478–82.

The Author(s) BMC Medical Genetics 2016, 17(Suppl 1):68

2.
3.

4.
5.
6.
7.

8.
9.
10.

11.

12.

13.

14.

15.

16.

17.

18.
19.

20.

21.

22.

23.

24.

Sandell LJ. Etiology of osteoarthritis: genetics and synovial joint
development. Nat Rev Rheumatol. 2012;8(2):77–89.
Luo SX, Li S, Zhang XH, Zhang JJ, Long GH, Dong GF, Su W, Deng Y, Liu Y,
Zhao JM, et al. Genetic polymorphisms of interleukin-16 and risk of knee
osteoarthritis. PLoS One. 2015;10(5), e0123442.
Kristjansson B, Honsawek S. Current perspectives in mesenchymal stem celltherapies for osteoarthritis. Stem Cells Int. 2014;2014:194318.
Panoutsopoulou K, Zeggini E. Advances in osteoarthritis genetics. J Med
Genet. 2013;50(11):715–24.
van der Kraan PM. Understanding developmental mechanisms in thecontext of osteoarthritis. Curr Rheumatol Rep. 2013;15(6):333.
Maldonado M, Nam J. The role of changes in extracellular matrix of cartilage inthe presence of inflammation on the pathology of osteoarthritis. Biomed Res
Int. 2013;2013:284873.
Brooks P. Inflammation as an important feature of osteoarthritis. Bull World
Health Organ. 2003;81(9):689–90.
Goldring SR, Goldring MB. The role of cytokines in cartilage matrix degenerationin osteoarthritis. Clin Orthop Relat Res. 2004(427 Suppl):S27–36.
Han L, Lee HS, Yoon JH, Choi WS, Park YG, Nam SW, Lee JY, Park WS. Associationof IL-17A and IL-17F single nucleotide polymorphisms with susceptibility toosteoarthritis in a Korean population. Gene. 2014;533(1):119–22.
Hulin-Curtis SL, Bidwell JL, Perry MJ. Evaluation of IL18 and IL18R1
polymorphisms: genetic susceptibility to knee osteoarthritis. Int J
Immunogenet. 2012;39(2):106–9.
Kaarvatn MH, Jotanovic Z, Mihelic R, Etokebe GE, Mulac-Jericevic B, Tijanic T,
Balen S, Sestan B, Dembic Z. Associations of the interleukin-1 gene locus
polymorphisms with risk to hip and knee osteoarthritis: gender andsubpopulation differences. Scand J Immunol. 2013;77(2):151–61.
Kaewkiattiyot S, Honsawek S, Vejchapipat P, Chongsrisawat V, Poovorawan
Y. Association of X-prolyl aminopeptidase 1 rs17095355 polymorphism withbiliary atresia in Thai children. Hepatol Res. 2011;41(12):1249–52.
Yigit S, Inanir A, Tekcan A, Tural E, Ozturk GT, Kismali G, Karakus N.
Significant association of interleukin-4 gene intron 3 VNTR polymorphismwith susceptibility to knee osteoarthritis. Gene. 2014;537(1):6–9.
Dai L, Zhang X, Hu X, Zhou C, Ao Y. Silencing of microRNA-101 prevents IL1beta-induced extracellular matrix degradation in chondrocytes. Arthritis
Res Ther. 2012;14(6):R268.
Tung JT, Arnold CE, Alexander LH, Yuzbasiyan-Gurkan V, Venta PJ, Richardson
DW, Caron JP. Evaluation of the influence of prostaglandin E2 on recombinantequine interleukin-1beta-stimulated matrix metalloproteinases 1, 3, and 13 andtissue inhibitor of matrix metalloproteinase 1 expression in equinechondrocyte cultures. Am J Vet Res. 2002;63(7):987–93.
Knowlton RG, Katzenstein PL, Moskowitz RW, Weaver EJ, Malemud CJ, Pathria
MN, Jimenez SA, Prockop DJ. Genetic linkage of a polymorphism in the type II
procollagen gene (COL2A1) to primary osteoarthritis associated with mild
chondrodysplasia. N Engl J Med. 1990;322(8):526–30.
Bateman JF. Genetic aspects of osteoarthritis. Semin Arthritis Rheum.
2005;34(6 Suppl 2):15–8.
Day-Williams AG, Southam L, Panoutsopoulou K, Rayner NW, Esko T, Estrada K,
Helgadottir HT, Hofman A, Ingvarsson T, Jonsson H, et al. A variant in MCF2L is
associated with osteoarthritis. Am J Hum Genet. 2011;89(3):446–50.
Evangelou E, Valdes AM, Kerkhof HJ, Styrkarsdottir U, Zhu Y, Meulenbelt I,
Lories RJ, Karassa FB, Tylzanowski P, Bos SD, et al. Meta-analysis of genomewide association studies confirms a susceptibility locus for knee
osteoarthritis on chromosome 7q22. Ann Rheum Dis. 2011;70(2):349–55.
Kerkhof HJ, Lories RJ, Meulenbelt I, Jonsdottir I, Valdes AM, Arp P, Ingvarsson
T, Jhamai M, Jonsson H, Stolk L, et al. A genome-wide association study
identifies an osteoarthritis susceptibility locus on chromosome 7q22.
Arthritis Rheum. 2010;62(2):499–510.
Miyamoto Y, Mabuchi A, Shi D, Kubo T, Takatori Y, Saito S, Fujioka M, Sudo
A, Uchida A, Yamamoto S, et al. A functional polymorphism in the 5′ UTR of
GDF5 is associated with susceptibility to osteoarthritis. Nat Genet.
2007;39(4):529–33.
Brown AJ, Alicknavitch M, D’Souza SS, Daikoku T, Kirn-Safran CB, MarchettiD, Carson DD, Farach-Carson MC. Heparanase expression and activity
influences chondrogenic and osteogenic processes during endochondralbone formation. Bone. 2008;43(4):689–99.
Vicent S, Luis-Ravelo D, Anton I, Garcia-Tunon I, Borras-Cuesta F, Dotor J, De
Las RJ, Lecanda F. A novel lung cancer signature mediates metastatic bonecolonization by a dual mechanism. Cancer Res. 2008;68(7):2275–85.

Page 13 of 23

25. Lu M, Munger JS, Steadele M, Busald C, Tellier M, Schnapp LM. Integrinalpha8beta1 mediates adhesion to LAP-TGFbeta1. J Cell Sci.
2002;115(Pt 23):4641–8.
26. Turner CE. Paxillin and focal adhesion signalling. Nat Cell Biol. 2000;2(12):E231–6.
27. Park SJ, Kim SJ, Rhee Y, Byun JH, Kim SH, Kim MH, Lee EJ, Lim SK. Fidgetinlike 1 gene inhibited by basic fibroblast growth factor regulates theproliferation and differentiation of osteoblasts. J Bone Miner Res.
2007;22(6):889–96.
28. Engel E, Viargues P, Mortier M, Taillebourg E, Coute Y, Thevenon D, FauvarqueMO. Identifying USPs regulating immune signals in Drosophila: USP2
deubiquitinates Imd and promotes its degradation by interacting withthe proteasome. Cell Commun Signal. 2014;12:41.
29. Fratazzi C, Manjunath N, Arbeit RD, Carini C, Gerken TA, Ardman B, RemoldO’Donnell E, Remold HG. A macrophage invasion mechanism for mycobacteria
implicating the extracellular domain of CD43. J Exp Med. 2000;192(2):183.
30. Edwards TL, Michels KA, Hartmann KE, Velez Edwards DR. BET1L andTNRC6B associate with uterine fibroid risk among European Americans.
Hum Genet. 2013;132(8):943–53.
31. Timasheva YR, Nasibullin TR, Imaeva EB, Erdman VV, Kruzliak P, Tuktarova IA,
Nikolaeva IE, Mustafina OE. Polymorphisms of inflammatory markers and riskof essential hypertension in Tatars from Russia. Clin Exp Hypertens (NewYork, NY: 1993). 2015;37(5):398–403.
32. Loeser RF, Varnum BC, Carlson CS, Goldring MB, Liu ET, Sadiev S, Kute TE,
Wallin R. Human chondrocyte expression of growth-arrest-specific gene 6
and the tyrosine kinase receptor axl: potential role in autocrine signaling in
cartilage. Arthritis Rheum. 1997;40(8):1455–65.
33. Tschopp J, Martinon F, Burns K. NALPs: a novel protein family involved ininflammation. Nat Rev Mol Cell Biol. 2003;4(2):95–104.

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