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INDIVIDUAL RESEARCHER

Xiaochun Long , Ph.D
Assistant Professor
e-mail: longx@mail.amc.edu

Phone: 518-264-2539
Fax: 518-262-8101

Education

2003 - Ph.D from Tongji Medical College, Huazhong University of Science and Technology


Current Research

 My research has been focused on defining novel molecular mechanisms controlling vascular remodeling, including vascular smooth muscle (VSMC) phenotypic modulation which underlies diverse vascular pathologies. Approaches employed in my lab include unbiased genome-wide RNA deep sequencing (RNA-seq) for identifying novel long noncoding RNAs (lncRNAs) and protein coding genes, comparative genomics analysis, and cutting edge techniques  of molecular and cellular biology such as ChIP assays, RNA pulldown, RNA-FISH, and confocal microscopy. We also collaborate with AMC surgeons to implement an ex vivo human blood vessel culture system and use innovative genetic mouse tools (transgenics and knockout mouse strains) for functional characterization of novel gene targets in vascular disease models such as arteriovenous fistula (AVF) failure, vascular injury and atherosclerosis.  Three major active ongoing projects are described as follows:

Molecular mechanism of venous maturation in arteriovenous fistula

End-stage kidney disease (ESRD) is a prevalent and costly disease associated with high morbidity and mortality. Due to the limited availability of donor kidneys for transplantation and no existing therapy for reversing the damage of the diseased kidney, hemodialysis is the most widely accepted treatment.  An arteriovenous fistula (AVF) involving a surgery to join a vein and artery in the arm, is currently the preferred conduit conferring the optimal vascular access for hemodialysis. However, our understanding of vein remodeling in the AVF is unacceptably elusive due to the lack of a clinically relevant AVF animal model and definitive tools to identify molecular events during the venous remodeling.
When the vein is exposed to the arterial environment, venous dilation and thickening are the major characteristics of the remodeled vein; a process towards arterializations also referred to as venous maturation which is the key to determine the patency of AVF. We recently established an innovative and technically challenging AVF mouse model which can recapitulate the human AVF process. Using genetic tools including lineage tracing mouse strains, tissue-specific inducible knockout mice combined with human AVF samples in collaborating with Dr. Arif Asif (AMC, Department of Nephrology), we are uniquely poised to dissect the cell origins and molecular mechanisms contributing to venous maturation.

Regulation and functionality of novel long non-coding RNAs in VSMC phenotypic modulation
With advanced DNA sequencing technologies and sophisticated bioinformatics approaches, a new view of the human genome has emerged recently. There is now consensus that the genome undergoes “pervasive transcription” and the majority (98%) of transcribed sequences is non-coding RNAs which include short non-coding RNAs (such as microRNAs) and long non-coding RNAs (lncRNAs). Currently, there is a paucity of information regarding lncRNAs function in vascular pathobiology.  In order to identify novel regulators of vascular disease, we performed RNA-seq analysis and lncRNA array assays in multiple innovative VSMC differentiation model systems. So far, we discovered over 900 lncRNAs being tightly regulated by VSMC differentiation; a number comparable to protein coding genes in these systems.  Significantly, we found a subset of those lncRNAs had a VSMC-restricted expression profile. Preliminary experiments have revealed the expression of these novel VSMC-selective lncRNAs is closely correlated with human vascular diseases such as AVF failure and atherosclerosis.  Our long term goal is to define the functionality and underlying molecular mechanisms of these novel lncRNAs in VSMC phenotypic modulation by utilizing the established VSMC culture systems, transgenic/knockout mouse models and vessels from patients with vascular disease in collaborating Dr. Bennett Edward (AMC, Division of Cardiothoracic Surgery) .
      
Define the role of novel TGFβ1/MYOCD-regulated protein coding genes in VSMC phenotypic adaptation
The aforementioned RNA-seq and RNA microarray data also uncovered a number of novel protein-coding genes (such as TSPAN2, MAMDC2) which are potentially important in VSMC phenotypic adaptation. One of our future goals is to define the role of these novel protein coding targets in different vascular disease models such as carotid artery ligation model, mouse abdominal aortic aneurysym (AAA) and AV F models.
 

 



PubMed Publications

  1. Vengrenyuk Y, Nishi H, Long X, Ouimet M, Savji N, Martinez FO, Cassella CP, Moore KJ, Ramsey SA, Miano JM, Fisher EA. Arterioscler Thromb Vasc Biol. 2015, 114.304029. [Epub ahead of print]


  2. Ackers-Johnson M, Talasila A, Sage AP, Long X, Bot I, Morrell NW, Bennett MR, Miano JM, Sinha S. Myocardin Regulates Vascular Smooth Muscle Cell Inflammatory Activation and Disease. Arterioscler Thromb Vasc Biol. 2015, 114.305218. [Epub ahead of print]


  3. Long X*, Bell RD* , Lin M*, Bergmann JH, Nanda V, Cowan SL, Zhou Q, Han Y, Spector DL, Zheng D, Miano JM. Identification and Initial Functional Characterization of a Human Vascular Cell-Enriched Long Noncoding RNA. Arterioscler Thromb Vasc Biol. 2014 Feb 27. * equal contribution


  4. Long X, Miano JM. Myocardin: new therapeutic agent in vascular disease? Arterioscler Thromb Vasc Biol. 2013, 33(10):2284-5.


  5. Shi G, Field DJ, Long X, Mickelsen D, Ko KA, Ture S, Korshunov VA, Miano JM, Morrell CN. Platelet factor 4 mediates vascular smooth muscle cell injury responses. Blood. 2013, 121(21):4417-27.


  6. Imamura M, Sugino Y, Long X, Slivano OJ, Nishikawa N, Yoshimura N, Miano JM. Myocardin and MicroRNA-1 modulate bladder activity through connexin 43 expression during post-natal development. J Cell Physiol. 2013, doi: 10.1002/jcp.24333.


  7. Long X, Cowan SL, Miano JM. MAPK14 is a Homeostatic Switch for the Vascular Smooth Muscle Cell Contractile Gene Program. Arterioscler Thromb Vasc Biol. 2013, 33(2):378- 86. (Cover Photograph) (Corresponding author)


  8. Kitchen CM, Cowan SL, Long X, Miano JM. Expression and promoter analysis of a highly restricted integrin alpha gene in vascular smooth muscle. Gene. 2013, 513(1): 82-9.


  9. Long X, Slivano OJ, Cowan SL, Georger MA, Lee TH, Miano JM. Smooth Muscle Calponin: An Unconventional CArG-Dependent Gene That Antagonizes Neointimal Formation. Arterioscler Thromb Vasc Biol. 2011, 31(10): 2172-80. (Cover Photograph)


  10. Long X, Miano JM. TGF?1 utilizes distinct pathways for the transcriptional activation of microRNA 143/145 in human coronary artery smooth muscle cells. J Biol Chem. 2011, 286(34):30119-29. (Co-corresponding author)


  11. Benson CC, Zhou Q, Long X, Miano JM. Identifying Functional Single Nucleotide Polymorphisms in the Human CArGome. Physiol Genomics. 2011, 43(18): 1038-48.


  12. Streb JW, Long X, Lee TH, Sun Q, Kitchen CM, Georger MA, Slivano OJ, Blaner WS, Carr DW, Gelman IH, Miano JM. Retinoid-induced expression and activity of an immediate early tumor suppressor gene in vascular smooth muscle cells. PLoS One. 2011, 6(4):e18538


  13. Xie WB, Li Z, Miano JM, Long X, Chen SY. Smad3-mediated myocardin silencing: a novel mechanism governing the initiation of smooth muscle differentiation. J Biol Chem. 2011, 286(17):15050-7.


  14. Imamura M, Long X, Nanda V, Miano JM. Expression and Functional Activity of Four Myocardin Isoforms. Gene. 2010, 464(1-2):1-10.


  15. Long X, Tharp DL, Georger MA, Slivano OJ, Lee MY, Wamhoff BR, Bowles DK, Miano JM. The smooth muscle cell-restricted KCNMB1 ion channel subunit is a direct transcriptional target of serum response factor and myocardin. J Biol Chem. 2009 284(48):33671-82.


  16. Sun Q, Taurin S, Sethakorn N, Long X, Imamura M, Wang DZ, Zimmer WE, Dulin NO, Miano JM. Myocardin-dependent activation of the CArG box-rich smooth muscle gamma-actin gene: preferential utilization of a single CArG element through functional association with the NKX3.1 homeodomain protein. J Biol Chem. 2009, 284(47):32582-90.


  17. Bell RD, Deane R, Chow N, Long X, Sagare A, Singh I, Streb JW, Guo H, Rubio A, Van Nostrand W, Miano JM, Zlokovic BV. SRF and myocardin regulate LRP-mediated amyloid-beta clearance in brain vascular cells. Nat Cell Biol. 2009, 11(2):143-53.


  18. Long X, Bell RD, Gerthoffer WT, Zlokovic BV, Miano JM. Myocardin Is Sufficient for a Smooth Muscle-Like Contractile Phenotype. Arterioscler Thromb Vasc Biol. 2008, 28(8):1505-10.


  19. Long X*, Davis JL*, Georger MA, Scott IC, Rich A, Miano JM. Expression and comparative genomics of two serum response factor genes in zebrafish. Int J Dev Biol. 2008, 52(4):389-96. * equal contribution


  20. Long X*, Creemers E.E*. Wang D.Z., Olson E.N., and Miano. J.M. Myocardin is a bifunctional switch for smooth versus skeletal muscle differentiation. Proc Natl Acad Sci U S A. 2007, 104(42):16570-5 * equal contribution


  21. Long X, Miano JM. Remote control of gene expression. J. Biol. Chem. 2007, 282(22): 15941-15945.


  22. Miano, J.M., Long X, Fujiwara, K. Serum response factor: master regulator of the actin cytoskeleton and contractile apparatus. Am J Physiol Cell Physiol. 2007, 292: C70-C81.


  23. Rensen, S.S.M., Niessen, P.M.G., Long, X, Doevendans, P.A., Miano, J.M., van Eys, G.J.J.M. Contribution of serum response factor and myocardin to transcriptional regulation of smoothelins. Cardiovasc.Res. 2006, 70:136-145.


  24. Sun Q, Chen G, Streb JW, Long X, Yang Y, Stoeckert CJ Jr, Miano JM. Defining the mammalian CArGome. Genome Res. 2006, 16:197-207.