Smooth Muscle Expression of Lipoma Preferred Partner Is Mediated by an Alternative Intronic Promoter That Is Regulated by Serum Response Factor/Myocardin

Integration of Selection Signatures and Protein Interactions Reveals NR6A1, PAPPA2, and PIK3C2B as the Promising Candidate Genes Underlying the Characteristics of Licha Black Pig

Licha black (LI) pig has the specific characteristics of larger body length and appropriate fat deposition among Chinese indigenous pigs. Body length is one of the external traits that affect production performance, and fat deposition influences meat quality. However, the genetic characteristics of LI pigs have not yet been systematically uncovered. Here, the genomic information from 891 individuals of LI pigs, commercial pigs, and other Chinese indigenous pigs was used to analyze the breed characteristics of the LI pig with runs of homozygosity, haplotype, and FST selection signatures. The results showed the growth traits-related genes (i.e., NR6A1 and PAPPA2) and the fatness traits-related gene (i.e., PIK3C2B) were the promising candidate genes that closely related to the characteristics of LI pigs. In addition, the protein–protein interaction network revealed the potential interactions between the promising candidate genes and the FASN gene. The RNA expression data from FarmGTEx indicated that the RNA expression levels of NR6A1, PAPPA2, PIK3C2B, and FASN were highly correlated in the ileum. This study provides valuable molecular insights into the mechanisms that affect pig body length and fat deposition, which can be used in the further breeding process to improve meat quality and commercial profitability.

Lin11-Isl1-Mec3 Domain Proteins as Mechanotransducers in Endothelial and Vascular Smooth Muscle Cells

Arterial hypertension is the leading risk factor for cardiovascular morbidity and mortality worldwide. However, little is known about the cellular mechanisms underlying it. In small arteries and arterioles, a chronic increase in blood pressure raises wall tension and hence stretches, namely, the medial vascular smooth muscle cells (VSMC) but also endothelial cell (EC) to cell contacts. Initially compensated by an increase in vascular tone, the continuous biomechanical strain causes a prominent change in gene expression in both cell types, frequently driving an arterial inward remodeling process that ultimately results in a reduction in lumen diameter, stiffening of the vessel wall, and fixation of blood pressure, namely, diastolic blood pressure, at the elevated level. Sensing and propagation of this supraphysiological stretch into the nucleus of VSMC and EC therefore seems to be a crucial step in the initiation and advancement of hypertension-induced arterial remodeling. Focal adhesions (FA) represent an important interface between the extracellular matrix and Lin11-Isl1-Mec3 (LIM) domain-containing proteins, which can translocate from the FA into the nucleus where they affect gene expression. The varying biomechanical cues to which vascular cells are exposed can thus be rapidly and specifically propagated to the nucleus. Zyxin was the first protein described with such mechanotransducing properties. It comprises 3 C-terminal LIM domains, a leucine-rich nuclear export signal, and N-terminal features that support its association with the actin cytoskeleton. In the cytoplasm, zyxin promotes actin assembly and organization as well as cell motility. In EC, zyxin acts as a transcription factor, whereas in VSMC, it has a less direct effect on mechanosensitive gene expression. In terms of homology and structural features, lipoma preferred partner is the nearest relative of zyxin among the LIM domain proteins. It is almost exclusively expressed by smooth muscle cells in the adult, resides like zyxin at FA but seems to affect mechanosensitive gene expression indirectly, possibly via altering cortical actin dynamics. Here, we highlight what is currently known about the role of these LIM domain proteins in mechanosensing and transduction in vascular cells.

Adipose-Derived Stromal Cells from Lipomas: Isolation, Characterisation and Review of the Literature

OBJECTIVE

The aim of this study was to characterize adipose-derived stromal cells (ADSCs) from patients diagnosed with multiple symmetric lipomatosis (MSL) in order to obtain potentially new insights into the pathophysiology, pathogenesis and treatment of this disease.

METHODS

Cells from the stromal vascular fraction were analysed by the colony-forming efficiency assay and flow cytometry using standard markers. Moreover, the power of adipogenic plasticity was evaluated. Finally, a literature review was performed from 1982 to 2015 using the US National Institutes of Health's PubMed database.

RESULTS

Three European-descent patients diagnosed with either MSL type I or II could be identified for analysis. The resulting mean colony-forming efficiency assay was 14.3 ± 5%. Flow-cytometric analysis of the ADSCs revealed high levels of CD34 (70 ± 9%), CD45 (37 ± 13%) and CD73 (55.8 ± 14%), whereas low levels of CD31 (16.8 ± 14%) and CD105 (5.8 ± 0.7%) were detected. Furthermore, ADSCs showed a strong adipogenic potential, which is in line with the literature review. The stem cell pool in lipoma shows several alterations in biological activities, such as proliferation, apoptosis and stemness.

CONCLUSIONS

ADSCs from lipoma may be interesting in the application of regenerative medicine. We discuss possible molecular treatment options to regulate their activities at the source of the MSL.

Smooth muscle differentiation identifies two classes of poorly differentiated pleomorphic sarcomas with distinct outcome

The clinical relevance of accurately diagnosing pleomorphic sarcomas has been shown, especially in cases of undifferentiated pleomorphic sarcomas with myogenic differentiation, which appear significantly more aggressive. To establish a new smooth muscle differentiation classification and to test its prognostic value, 412 sarcomas with complex genetics were examined by immunohistochemistry using four smooth muscle markers (calponin, h-caldesmon, transgelin and smooth muscle actin). Two tumor categories were first defined: tumors with positivity for all four markers and tumors with no or incomplete phenotypes. Multivariate analysis demonstrated that this classification method exhibited the strongest prognostic value compared with other prognostic factors, including histological classification. Secondly, incomplete or absent smooth muscle phenotype tumor group was then divided into subgroups by summing for each tumor the labeling intensities of all four markers for each tumors. A subgroup of tumors with an incomplete but strong smooth muscle differentiation phenotype presenting an intermediate metastatic risk was thus identified. Collectively, our results show that the smooth muscle differentiation classification method may be a useful diagnostic tool as well as a relevant prognostic tool for undifferentiated pleomorphic sarcomas.

TGF-β1-induced LPP expression dependant on Rho kinase during differentiation and migration of bone marrow-derived smooth muscle progenitor cells

Lipoma preferred partner (LPP) has been identified as a protein which is highly selective for smooth muscle progenitor cells (SMPCs) and regulates differentiation and migration of SMPCs, but mechanisms of LPP expression are not elucidated clearly. The aim of the present study was to discuss the mechanisms by which LPP expression is regulated in the differentiation and migration of SMPCs induced by TGF-β1. It was found that TGF-β1 could significantly increase the expression of LPP, smooth muscle α-actin, smooth muscle myosin heavy chain (SM-MHC), and smoothelin in SMPCs. Moreover, inactivation of Rho kinase (ROK) with ROK inhibitors significantly inhibited LPP mRNA expression in TGF-β1-treated SMPCs and mouse aortic smooth muscle cells (MAoSMCs). At the same time, LPP silencing with short interfering RNA significantly decreased SMPCs migration. In conclusion, LPP appears to be a ROK-dependant SMPCs differentiation marker that plays a role in regulating SMPCs migration.

The function of introns

The intron–exon architecture of many eukaryotic genes raises the intriguing question of whether this unique organization serves any function, or is it simply a result of the spread of functionless introns in eukaryotic genomes. In this review, we show that introns in contemporary species fulfill a broad spectrum of functions, and are involved in virtually every step of mRNA processing. We propose that this great diversity of intronic functions supports the notion that introns were indeed selfish elements in early eukaryotes, but then independently gained numerous functions in different eukaryotic lineages. We suggest a novel criterion of evolutionary conservation, dubbed intron positional conservation, which can identify functional introns.

Cell Adhesion and Transcriptional Activity - Defining the Role of the Novel Protooncogene LPP

Integrating signals from the extracellular matrix through the cell surface into the nucleus is an essential feature of metazoan life. To date, many signal transducers known as shuttle proteins have been identified to act as both a cytoskeletal and a signaling protein. Among them, the most prominent representatives are zyxin and lipoma preferred (translocation) partner (LPP). These proteins belong to the LIM domain protein family and are associated with cell migration, proliferation, and transcription. LPP was first identified in benign human lipomas and was subsequently found to be overexpressed in human malignancies such as lung carcinoma, soft tissue sarcoma, and leukemia. This review portrays LPP in the context of human neoplasia based on a study of the literature to define its important role as a novel protooncogene in carcinogenesis.

Conservation and evolution in and among SRF- and MEF2-type MADS domains and their binding sites

Serum response factor (SRF) and myocyte enhancer factor 2 (MEF2) represent two types of members of the MCM1, AGAMOUS, DEFICIENS, and SRF (MADS)-box transcription factor family present in animals and fungi. Each type has distinct biological functions, which are reflected by the distinct specificities of the proteins bound to their cognate DNA-binding sites and activated by their respective cofactors. However, little is known about the evolution of MADS domains and their DNA-binding sites. Here, we report on the conservation and evolution of the two types of MADS domains with their cognate DNA-binding sites by using phylogenetic analyses. First, there are great similarities between the two types of proteins with amino acid positions highly conserved, which are critical for binding to the DNA sequence and for the maintenance of the 3D structure. Second, in contrast to MEF2-type MADS domains, distinct conserved residues are present at some positions in SRF-type MADS domains, determining specificity and the configuration of the MADS domain bound to DNA sequences. Furthermore, the ancestor sequence of SRF- and MEF2-type MADS domains is more similar to MEF2-type MADS domains than to SRF-type MADS domains. In the case of DNA-binding sites, the MEF2 site has a T-rich core in one DNA sequence and an A-rich core in the reverse sequence as compared with the SRF site, no matter whether where either A or T is present in the two complementary sequences. In addition, comparing SRF sites in the human and the mouse genomes reveals that the evolution rate of CArG-boxes is faster in mouse than in human. Moreover, interestingly, a CArG-like sequence, which is probably functionless, could potentially mutate to a functional CArG-box that can be bound by SRF and vice versa. Together, these results significantly improve our knowledge on the conservation and evolution of the MADS domains and their binding sites to date and provide new insights to investigate the MADS family, which is not only on evolution of MADS factors but also on evolution of their binding sites and even on coevolution of MADS factors with their binding sites.

Characteristics of the CArG-SRF binding context in mammalian genomes

Serum response factor (SRF), a member of the MADS family, binds a 10-bp cis element known as the CArG box. However, despite our extensive knowledge of SRF and the CArG box, limited information is available on the CArG-SRF binding context or how CArG flanking sequences are defined. We used statistical tests and computer simulation to find characteristics of the CArG-SRF binding context. Based on the combination of published literature and a search of DBTSS, 150 and 136 functional CArG boxes together with 10 bp flanking on each side were found in mouse and human genomes, respectively. By statistical analysis of the 30 positions we found some new conserved positions of interest (P < 0.005) such as -15, -8, and +8, in addition to the ten highly conserved positions of the CArG box. Intriguingly, studies comparing the flanking positions between consensus CArG boxes and CArG-like boxes showed that there are more conserved positions in the latter. Moreover, CpG content within the CArG-SRF binding context is much higher than that within introns. Collectively, these results suggest that there are some special pre-existing features in the flanking sequences of functional CArG boxes probably contributing to SRF selectively recognizing and binding to the functional CArG from millions of functionless CArG boxes in mammalian genomes. This is a significant step toward understanding the mechanism of transcriptional regulation of SRF-dependent genes.

Strong smooth muscle differentiation is dependent on myocardin gene amplification in most human retroperitoneal leiomyosarcomas

Myocardin (MYOCD), a serum response factor (SRF) transcriptional cofactor, is essential for cardiac and smooth muscle development and differentiation. We show here by array-based comparative genomic hybridization, fluorescence in situ hybridization, and expression analysis approaches that MYOCD gene is highly amplified and overexpressed in human retroperitoneal leiomyosarcomas (LMS), a very aggressive well-differentiated tumor. MYOCD inactivation by shRNA in a human LMS cell line with MYOCD locus amplification leads to a dramatic decrease of smooth muscle differentiation and strongly reduces cell migration. Moreover, forced MYOCD expression in three undifferentiated sarcoma cell lines and in one liposarcoma cell line confers a strong smooth muscle differentiation phenotype and increased migration abilities. Collectively, these results show that human retroperitoneal LMS differentiation is dependent on MYOCD amplification/overexpression, suggesting that in these well-differentiated LMS, differentiation could be a consequence of an acquired genomic alteration. In this hypothesis, these tumors would not necessarily derive from cells initially committed to smooth muscle differentiation. These data also provide new insights on the cellular origin of these sarcomas and on the complex connections between oncogenesis and differentiation in mesenchymal tumors.

Mechanical properties of the extracellular matrix alter expression of smooth muscle protein LPP and its partner palladin; relationship to early atherosclerosis and vascular injury

Lipoma preferred partner (LPP) localizes to focal adhesions/dense bodies, is selectively expressed in smooth muscle cells (SMC) and enhances cell migration. SMCs cultured on denatured collagen or on a rigid substrate, up regulated expression of LPP, its partner palladin, tenascin C (TN-C), phosphorylated focal adhesion kinase (pFAK) and exhibited robust stress fibers. In an endothelial (EC)/SMC hemodynamic flow system, shear stress waveforms mimicking atheroprone flow, applied to the EC layer, significantly decreased expression of SMC LPP and palladin. They were also down regulated with TN-C, in an ApoE murine model of atherosclerosis and with oxidative stress but up regulated in an arterial injury model in response to upstream sequential changes in pFAK, Prx1 and TN-C. In conclusion, expression of LPP and palladin are modulated by a mix of mechanical cues, oxidative stress and substrate composition which translate into their up or down regulation in vessel wall injury and early atherogenesis.

Targeted disruption of the mouse Lipoma Preferred Partner gene

LPP (Lipoma Preferred Partner) is a zyxin-related cell adhesion protein that is involved in the regulation of cell migration. We generated mice with a targeted disruption of the Lpp gene and analysed the importance of Lpp for embryonic development and adult functions. Aberrant Mendelian inheritance in heterozygous crosses suggested partial embryonic lethality of Lpp(-/-) females. Fertility of Lpp(-/-) males was proven to be normal, however, females from Lpp(-/-) x Lpp(-/-) crosses produced a strongly reduced number of offspring, probably due to a combination of female embryonic lethality and aberrant pregnancies. Apart from these developmental and reproductive abnormalities, Lpp(-/-) mice that were born reached adulthood without displaying any additional macroscopic defects. On the other hand, Lpp(-/-) mouse embryonic fibroblasts exhibited reduced migration capacity, reduced viability, and reduced expression of some Lpp interaction partners. Finally, we discovered a short nuclear form of Lpp, expressed mainly in testis via an alternative promoter.