title: Distinct roles of two alternative splice variants of matrilin-2 in protein             oligomerization and proteolysis.
abstract: Matrilin-2 (matn2) contains a unique domain, between the second von Willebrand             factor A (vWFA) domain and the C-terminal coiled-coil domain, with no sequence             homology with other family members. Complementary DNA (cDNA) sequence analysis             of matn2 expression in both mice and humans revealed an alternative splice site             in the region of the unique domain, which forms a short and a long splicing variant             (containing an additional 19 amino acids). However, the expression heterogeneity             of the alternative spliced variants, and the roles of the unique domain in oligomerization             and proteolysis of matn2 are unknown. In this study, we examined the expression             of the two alternative splice variants of matn2 in several skeletal and non-skeletal             tissues by reverse transcription-polymerase chain reaction. Both splice variants             of matn2 were detected at the mRNA level in all tissues studied. To explore the             biochemical significance, several minigene constructs containing the second vWFA             domain, the unique domain (with either a long or short form) and the coiled-coil             domain of mouse mini matn2 were generated. Ectopic expression of these constructs             demonstrated that the long form of matn2 is capable of self-assembling into several             oligomeric forms, including a tetramer, trimer, pentamer or multimer; but the             short form is only capable of forming a tetramer, trimer or dimer. Moreover, we             observed that the splice variants of matn2 are important in modulating matn2 cleavage             when co-expressed with matrilin-1 or matrilin-3. These results indicate that the             two alternative splice variants have distinct roles in the processes of post-translational             modification of matn2, which may have an impact on the homeostasis of the matrilin             filamentous network of the extracellular matrix.
authors.affiliation: Department of Neurology, Guangdong Medical College Affiliated Hospital, Zhanjiang 524001, PR China.
authors.forename: Longxuan
authors.initials: L
authors.lastname: Li
authors.forename: Liangqing
authors.initials: L
authors.lastname: Zhang
authors.forename: Yiming
authors.initials: Y
authors.lastname: Shao
authors.forename: Guirong
authors.initials: G
authors.lastname: Wang
authors.forename: Rujun
authors.initials: R
authors.lastname: Gong
authors.forename: Zhengke
authors.initials: Z
authors.lastname: Wang
authors.forename: Jinwu
authors.initials: J
authors.lastname: Peng
authors.forename: Shuhua
authors.initials: S
authors.lastname: Wang
authors.forename: David
authors.initials: D
authors.lastname: Genochio
authors.forename: Bin
authors.initials: B
authors.lastname: Zhao
authors.forename: Junming
authors.initials: J
authors.lastname: Luo
mesh_terms: D017398:Alternative Splicing; D000818:Animals; D000831:Animals, Newborn; D019556:COS Cells; D064236:Cartilage Oligomeric Matrix Protein; D002522:Chlorocebus aethiops; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000378:metabolism*; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D064235:Matrilin Proteins; D051379:Mice; D008810:Mice, Inbred C57BL; D010957:Plasmids / Q000235:genetics / Q000378:metabolism; D058105:Polymerization; D059748:Proteolysis; D012333:RNA, Messenger / Q000378:metabolism; D014162:Transfection; D014841:von Willebrand Factor / Q000737:chemistry
chemical_list: D064236:Cartilage Oligomeric Matrix Protein; D016326:Extracellular Matrix Proteins; D006023:Glycoproteins; C577539:MATN1 protein, human; C577540:Matn1 protein, mouse; C577542:Matn2 protein, mouse; C577546:Matn3 protein, mouse; D064235:Matrilin Proteins; D012333:RNA, Messenger; C577553:TSP5 protein, human; D014841:von Willebrand Factor