Disease relevance of SM1

• Immunoblotting experiments revealed that antibodies SM1 and SM2 recognize epitopes on two different peptides derived by CNBr cleavage of alpha-pili from Neisseria gonorrhoeae P9-2 [1].
• Expression of SM1 and SM2 MHCs was variable in the different leiomyomas studied [2].
• Cavernous malformations (CVMs) and arteriovenous malformations (AVMs) were immunostained for three smooth muscle cell (SMC)-specific protein markers (smooth muscle alpha-actin, SM1 and SM2) [3].
• However, strong expression of SMemb within the sac walls of male inguinal hernia and SM1 in hydrocele groups were observed [4].
• SM1 was expressed in myoepithelial cells of normal mammary glands and fibrocystic diseases and in myoepithelial-like tumor cells in the basal layer of fibroadenomas and phyllodes tumors [5].

High impact information on SM1

• This was corroborated by multipoint analysis, indicating a close proximity to CSF1R as the most likely location of SM1 [6].
• Neointimal SMCs recovered SM MHC expression, first SM1 and then SM2, by 6 months after PTCA [7].
• Expression of SM1 and SM2 in the neointima varied with the time after intervention, whereas alpha-actin was constitutively expressed in all cases studied [7].
• Smooth muscle myosin heavy chain (SM MHC) isoforms (SM1 and SM2) are specific markers for SMC differentiation [7].
• METHODS AND RESULTS: To determine SMC phenotypes in neointimal tissues after percutaneous transluminal coronary angioplasty (PTCA), we performed immunohistochemistry on human coronary arteries with antibodies against alpha-SM actin, SM1, SM2, and SMemb [7].

Biological context of SM1

• In this study, in order to elucidate any difference in the cellular phenotypes between mesangial cells and renal vascular smooth muscles, we investigated the localization of myosin heavy chain isoforms using a monoclonal antibody against SM1 and SM2 [8].
• Myosin heavy chain (MHC) isoforms such as SMemb, SM1 and SM2 are important molecular markers used to study vascular smooth muscle cell differentiation [9].
• Two myosin heavy chain isoforms expressed in smooth muscle, SM1 (204 kDa) and SM2 (200 kDa), are derived from alternate splicing that results in different amino acid sequences at their non-helical C-terminal tail regions [10].
• To localize this gene, referred to as SM1, we performed a genome-wide study on 142 Brazilian subjects belonging to 11 informative families Our results show a linkage to only one region, on chromosome 5q31-q33, with maximum two-point lod scores of +4.74 and +4.52 for D5S636 and the colony stimulating factor-1 receptor marker (CSF1R), respectively [6].
• Human susceptibility to Schistosoma mansoni infections is controlled by the SM1 locus on chromosome 5 in q31-q33 [11].

Anatomical context of SM1

• SM1 is specifically expressed in smooth muscles from early development and SM2 appears after birth [8].
• By double-fluorescence immunostaining of the tunica muscularis of the GI tract wall, co-expression of KIT, CD34, and SMemb was demonstrated in ICCs, which were negative for SM1 and SM2 [12].
• Therefore, in this study, to clarify the origin of MRT, the expressions of cytoplasmic proteins including smooth-muscle-specific proteins (alpha-smooth-muscle actin, basic calponin, smooth-muscle-myosin-heavy-chain isoforms of SM1 and SM2) in the primary-MRT tissue and cell line were analyzed [13].
• Recently it was demonstrated that vascular smooth muscles contain two types of myosin heavy chain (MHC) isoforms, SM1 and SM2, which are unique molecular markers of smooth muscle cell phenotypes [14].
• Antibody-mediated chemiluminescence of polymorphonuclear leukocytes was enhanced in the presence of human complement, and a weak opsonic effect was detected with one of the cross-reacting antibodies (SM1) when this system was used [1].

Associations of SM1 with chemical compounds

• An increase in the COOH-terminal myosin heavy chain isoform SM1-to-SM2 ratio with 17beta-estradiol treatment may underlie the changes observed in contractility [15].
• Long-term treatment with doxazosin induced differentiation tended towards a contractile phenotype, as indicated by an increase of the ratio of smooth muscle heavy chain myosin subtypes SM2/SM1 [16].
• Mineralization of poly(trans-1,4-isoprene) after 80 days varied from 3 % (strain SM1) to 54 % (strain SEI2b) and from 34 % (strain L1b) to 43 % (strain SH22a) for the cis-isomer after 78 days [17].
• The SM2 isoform was up-regulated during postnatal development and the SM1 to SM2 ratio changed during pregnancy and post-partum period but not with human gonadotropin treatment which increases the level of circulating progesterone [18].
• Myroides sp. strain SM1 possessed a biosynthetic route to cholic acid from cholesterol [19].

Other interactions of SM1

• Both SM1 and SM2 are specific to smooth muscles [8].
• Localization of SM1 and SM-2 was similar to that of alpha-smooth muscle actin (SM alpha-actin) [8].
• Septal spindle-shaped cells in LC lacked the cytoskeletal proteins specific to differentiated smooth muscle cells (CGA7, SM1, SM2 and desmin) [20].
• In fibronectin-cultured cells, strain elicited no increase in SM-1 [21].
• To determine if the SM1 gene segregates with the human MHC chromosomal region, we performed a linkage study by the lod score method [22].

Analytical, diagnostic and therapeutic context of SM1

• In the KP-MRT-NS cell line, the expression of neurofilament, alpha-smooth-muscle actin, basic calponin and smooth-muscle-myosin heavy chain of SM1 and SM2 isoforms was revealed by immunofluorescence, Western blot and/or reverse transcriptase-polymerase chain reaction (RT-PCR) [13].
• SM-2 to SM-1 mRNA ratios and expression of alpha1-adrenergic receptor subtypes were determined by means of reverse transcriptase polymerase chain reaction (RT-PCR) techniques [23].
• Indirect immunofluorescence with SM1 antibody allows detection of bone marrow metastasis of SCCL that cannot be seen by conventional morphology and can identify disseminated disease in patients otherwise staged limited disease [24].
• To overcome the problems associated with definitive identification, we developed species-specific PCR (SS-PCR) primers, designated SM1 and SM4, directed to the 23S rRNA gene, and tested their utility to accurately identify S. maltophilia directly from sputum [25].
• Mice injected with a lethal inoculum of SM1 cells were given two intraperitoneal injections (days 3 and 7 post-inoculation) of 100 microg soluble OX-40 L [26].

References