Ela W. Knapik, M.D.

Associate Professor

Faculty Appointments
Associate Professor of Medicine Associate Professor of Cell & Developmental Biology
M.D., Medicine, Jagiellonian University, Krakow, Poland
Office Address
507 Light Hall
2215 Garland Avenue
Nashville, TN 37232
Research Description
Our laboratory is interested in understanding mechanisms and pathways that direct neural crest stem cells, and mediate their differentiation into various derivatives. We use a particularly effective approach to dissect the complex processes of cell specification and differentiation namely a combination of embryological and genetic methods and ask how gene networks control cell behavior and cell fate.
The first steps en route to answer these questions, beginning with individual genes, is to develop and characterize mutations that produce specific neural crest phenotypes, and establish gene hierarchy and cooperation among regulators that will control neural crest progenitors specification and differentiation. Neural crest stem cell genes and the genetic mutations are our primary tools to study gene expression, regulation, epistasis, cell fate, behavior, proliferation and survival.
Our main model system, zebrafish (Danio rerio) lends itself superbly to genetic and developmental analysis because of abundant availability of transparent embryos developing outside the mother that are accessible to manipulation and direct observation. This small fish can be used in a mutagenesis screen and its genome is amenable to efficient positional cloning of mutations and phenotypic analysis. In parallel, we use mammalian cells in culture and biochemical approaches to address our questions.

We have focused our investigation on two areas:
(i) the genetic network of transcription factors orchestrating transition of neural crest stem cell to derivatives like craniofacial cartilage,
(ii) and the role of cellular secretory pathway in chondrocyte maturation.

We use positional cloning approaches to help us identify point mutations responsible for craniofacial malformations. We have already found a set of factors critical for neural crest specification in the mutations mont blanc, mother superior and quadro. Now, we are dissecting the genetic interactions among these factors and further search for novel components of the genetic network.
Concurrently, we are investigating a phenotypic series of mutations affecting chondrocyte differentiation. Chondrocytes originate from neural crest stem cells and constitute most of the larval head skeleton. Surprisingly, we have discovered that the mutations in crusher and bulldog loci disrupt genes in the cellular secretory pathway, while the stumpf locus is critical in posttranslational protein modification and folding. These results open a new vista for research on the role of secretory pathway in a global context of embryonic morphogenesis and disease.

Our long-term goal is not only to understand the molecular mechanisms governing neural crest biology, but also to provide insight to the etiology and pathogenesis of human congenital and environmentally induced birth defects affecting neural crest derivatives (face, cranial ganglia, heart, skin, fetal alcohol syndrome) and crest derived tumors (melanomas, neuroblastoma, and teratocarcinomas).
Research Keywords
Protein Secretion and Extracellular Matrix, Regulation of Cell Shape Changes in Morphogenesis
Zou P, Wu SY, Koteiche HA, Mishra S, Levic DS, Knapik E, Chen W, Mchaourab HS. A conserved role of aA-crystallin in the development of the zebrafish embryonic lens. Exp. Eye Res [print-electronic]. 2015 Sep; 138: 104-13. PMID: 26149094, PMCID: PMC4638411, PII: S0014-4835(15)00220-1, DOI: 10.1016/j.exer.2015.07.001, ISSN: 1096-0007.

Levic DS, Minkel JR, Wang WD, Rybski WM, Melville DB, Knapik EW. Animal model of Sar1b deficiency presents lipid absorption deficits similar to Anderson disease. J. Mol. Med [print-electronic]. 2015 Feb; 93(2): 165-76. PMID: 25559265, PMCID: PMC4319984, DOI: 10.1007/s00109-014-1247-x, ISSN: 1432-1440.

Levic DS, Minkel JR, Wang WD, Rybski WM, Melville DB, Knapik EW. Animal model of Sar1b deficiency presents lipid absorption deficits similar to Anderson disease. J. Mol. Med [print-electronic]. 2015 Feb; 93(2): 165-76. PMID: 25559265, PMCID: PMC4319984, DOI: 10.1007/s00109-014-1247-x, ISSN: 1432-1440.

Tanwar V, Bylund JB, Hu J, Yan J, Walthall JM, Mukherjee A, Heaton WH, Wang WD, Potet F, Rai M, Kupershmidt S, Knapik EW, Hatzopoulos AK. Gremlin 2 promotes differentiation of embryonic stem cells to atrial fate by activation of the JNK signaling pathway. Stem Cells. 2014 Jul; 32(7): 1774-88. PMID: 24648383, PMCID: PMC4123739, DOI: 10.1002/stem.1703, ISSN: 1549-4918.

Niu X, Hong J, Zheng X, Melville DB, Knapik EW, Meng A, Peng J. The nuclear pore complex function of Sec13 protein is required for cell survival during retinal development. J. Biol. Chem [print-electronic]. 2014 Apr 4/25/2014; 289(17): 11971-85. PMID: 24627485, PMCID: PMC4002104, PII: M114.547190, DOI: 10.1074/jbc.M114.547190, ISSN: 1083-351X.

Unlu G, Levic DS, Melville DB, Knapik EW. Trafficking mechanisms of extracellular matrix macromolecules: insights from vertebrate development and human diseases. Int. J. Biochem. Cell Biol [print-electronic]. 2014 Feb; 47: 57-67. PMID: 24333299, PMCID: PMC3915713, PII: S1357-2725(13)00343-9, DOI: 10.1016/j.biocel.2013.11.005, ISSN: 1878-5875.

Vacaru AM, Unlu G, Spitzner M, Mione M, Knapik EW, Sadler KC. In vivo cell biology in zebrafish - providing insights into vertebrate development and disease. J. Cell. Sci. 2014 Feb 2/1/2014; 127(Pt 3): 485-95. PMID: 24481493, PMCID: PMC4007761, PII: 127/3/485, DOI: 10.1242/jcs.140194, ISSN: 1477-9137.

Venkateswaran A, Sekhar KR, Levic DS, Melville DB, Clark TA, Rybski WM, Walsh AJ, Skala MC, Crooks PA, Knapik EW, Freeman ML. The NADH oxidase ENOX1, a critical mediator of endothelial cell radiosensitization, is crucial for vascular development. Cancer Res [print-electronic]. 2014 Jan 1/1/2014; 74(1): 38-43. PMID: 24247717, PMCID: PMC3947320, PII: 0008-5472.CAN-13-1981, DOI: 10.1158/0008-5472.CAN-13-1981, ISSN: 1538-7445.

Lee RT, Knapik EW, Thiery JP, Carney TJ. An exclusively mesodermal origin of fin mesenchyme demonstrates that zebrafish trunk neural crest does not generate ectomesenchyme. Development [print-electronic]. 2013 Jul; 140(14): 2923-32. PMID: 23739134, PMCID: PMC3699280, PII: dev.093534, DOI: 10.1242/dev.093534, ISSN: 1477-9129.

Müller II, Melville DB, Tanwar V, Rybski WM, Mukherjee A, Shoemaker MB, Wang WD, Schoenhard JA, Roden DM, Darbar D, Knapik EW, Hatzopoulos AK. Functional modeling in zebrafish demonstrates that the atrial-fibrillation-associated gene GREM2 regulates cardiac laterality, cardiomyocyte differentiation and atrial rhythm. Dis Model Mech [print-electronic]. 2013 Mar; 6(2): 332-41. PMID: 23223679, PMCID: PMC3597016, PII: dmm.010488, DOI: 10.1242/dmm.010488, ISSN: 1754-8411.

Wang WD, Melville DB, Montero-Balaguer M, Hatzopoulos AK, Knapik EW. Tfap2a and Foxd3 regulate early steps in the development of the neural crest progenitor population. Dev. Biol [print-electronic]. 2011 Dec 12/1/2011; 360(1): 173-85. PMID: 21963426, PMCID: PMC3236700, PII: S0012-1606(11)01263-2, DOI: 10.1016/j.ydbio.2011.09.019, ISSN: 1095-564X.

Melville DB, Montero-Balaguer M, Levic DS, Bradley K, Smith JR, Hatzopoulos AK, Knapik EW. The feelgood mutation in zebrafish dysregulates COPII-dependent secretion of select extracellular matrix proteins in skeletal morphogenesis. Dis Model Mech [print-electronic]. 2011 Nov; 4(6): 763-76. PMID: 21729877, PMCID: PMC3209646, PII: dmm.007625, DOI: 10.1242/dmm.007625, ISSN: 1754-8411.

Eames BF, Yan YL, Swartz ME, Levic DS, Knapik EW, Postlethwait JH, Kimmel CB. Mutations in fam20b and xylt1 reveal that cartilage matrix controls timing of endochondral ossification by inhibiting chondrocyte maturation. PLoS Genet [print-electronic]. 2011 Aug; 7(8): e1002246. PMID: 21901110, PMCID: PMC3161922, PII: PGENETICS-D-11-00175, DOI: 10.1371/journal.pgen.1002246, ISSN: 1553-7404.

Liu D, Wang WD, Melville DB, Cha YI, Yin Z, Issaeva N, Knapik EW, Yarbrough WG. Tumor suppressor Lzap regulates cell cycle progression, doming, and zebrafish epiboly. Dev. Dyn [print-electronic]. 2011 Jun; 240(6): 1613-25. PMID: 21523853, PMCID: PMC3287344, DOI: 10.1002/dvdy.22644, ISSN: 1097-0177.

Bradley KM, Breyer JP, Melville DB, Broman KW, Knapik EW, Smith JR. An SNP-Based Linkage Map for Zebrafish Reveals Sex Determination Loci. G3 (Bethesda). 2011 Jun 6/1/2011; 1(1): 3-9. PMID: 21949597, PMCID: PMC3178105, DOI: 10.1534/g3.111.000190, ISSN: 2160-1836.

Melville DB, Knapik EW. Traffic jams in fish bones: ER-to-Golgi protein transport during zebrafish development. Cell Adh Migr [print-electronic]. 2011 Mar; 5(2): 114-8. PMID: 21178403, PMCID: PMC3084976, PII: 14377, ISSN: 1933-6926.

Sarmah S, Barrallo-Gimeno A, Melville DB, Topczewski J, Solnica-Krezel L, Knapik EW. Sec24D-dependent transport of extracellular matrix proteins is required for zebrafish skeletal morphogenesis. PLoS ONE. 2010; 5(4): e10367. PMID: 20442775, PMCID: PMC2860987, DOI: 10.1371/journal.pone.0010367, ISSN: 1932-6203.

Kucenas S, Wang WD, Knapik EW, Appel B. A selective glial barrier at motor axon exit points prevents oligodendrocyte migration from the spinal cord. J. Neurosci. 2009 Dec 12/2/2009; 29(48): 15187-94. PMID: 19955371, PMCID: PMC2837368, PII: 29/48/15187, DOI: 10.1523/JNEUROSCI.4193-09.2009, ISSN: 1529-2401.

Granero-Moltó F, Sarmah S, O'Rear L, Spagnoli A, Abrahamson D, Saus J, Hudson BG, Knapik EW. Goodpasture antigen-binding protein and its spliced variant, ceramide transfer protein, have different functions in the modulation of apoptosis during zebrafish development. J. Biol. Chem [print-electronic]. 2008 Jul 7/18/2008; 283(29): 20495-504. PMID: 18424781, PMCID: PMC2459293, PII: M801806200, DOI: 10.1074/jbc.M801806200, ISSN: 0021-9258.

Bradley KM, Elmore JB, Breyer JP, Yaspan BL, Jessen JR, Knapik EW, Smith JR. A major zebrafish polymorphism resource for genetic mapping. Genome Biol. 2007; 8(4): R55. PMID: 17428331, PMCID: PMC1896001, PII: gb-2007-8-4-r55, DOI: 10.1186/gb-2007-8-4-r55, ISSN: 1474-760X.

Montero-Balaguer M, Lang MR, Sachdev SW, Knappmeyer C, Stewart RA, De La Guardia A, Hatzopoulos AK, Knapik EW. The mother superior mutation ablates foxd3 activity in neural crest progenitor cells and depletes neural crest derivatives in zebrafish. Dev. Dyn. 2006 Dec; 235(12): 3199-212. PMID: 17013879, DOI: 10.1002/dvdy.20959, ISSN: 1058-8388.

Lang MR, Lapierre LA, Frotscher M, Goldenring JR, Knapik EW. Secretory COPII coat component Sec23a is essential for craniofacial chondrocyte maturation. Nat. Genet [print-electronic]. 2006 Oct; 38(10): 1198-203. PMID: 16980978, PII: ng1880, DOI: 10.1038/ng1880, ISSN: 1061-4036.

Müller II, Knapik EW, Hatzopoulos AK. Expression of the protein related to Dan and Cerberus gene--prdc--During eye, pharyngeal arch, somite, and swim bladder development in zebrafish. Dev. Dyn. 2006 Oct; 235(10): 2881-8. PMID: 16921498, DOI: 10.1002/dvdy.20925, ISSN: 1058-8388.

Barrallo-Gimeno A, Holzschuh J, Driever W, Knapik EW. Neural crest survival and differentiation in zebrafish depends on mont blanc/tfap2a gene function. Development [print-electronic]. 2004 Apr; 131(7): 1463-77. PMID: 14985255, PII: dev.01033, DOI: 10.1242/dev.01033, ISSN: 0950-1991.

Holzschuh J, Barrallo-Gimeno A, Ettl AK, Durr K, Knapik EW, Driever W. Noradrenergic neurons in the zebrafish hindbrain are induced by retinoic acid and require tfap2a for expression of the neurotransmitter phenotype. Development [print-electronic]. 2003 Dec; 130(23): 5741-54. PMID: 14534139, PII: dev.00816, DOI: 10.1242/dev.00816, ISSN: 0950-1991.

Dethleffsen K, Heinrich G, Lauth M, Knapik EW, Meyer M. Insert-containing neurotrophins in teleost fish and their relationship to nerve growth factor. Mol. Cell. Neurosci. 2003 Oct; 24(2): 380-94. PMID: 14572460, PII: S1044743103001957, ISSN: 1044-7431.

Sachdev SW, Dietz UH, Oshima Y, Lang MR, Knapik EW, Hiraki Y, Shukunami C. Sequence analysis of zebrafish chondromodulin-1 and expression profile in the notochord and chondrogenic regions during cartilage morphogenesis. Mech. Dev. 2001 Jul; 105(1-2): 157-62. PMID: 11429291, PII: S0925477301004178, ISSN: 0925-4773.

Knapik EW. ENU mutagenesis in zebrafish--from genes to complex diseases. Mamm. Genome. 2000 Jul; 11(7): 511-9. PMID: 10886014, PII: 10.1007/s003350010098, ISSN: 0938-8990.

Chevrette M, Joly L, Tellis P, Knapik EW, Miles J, Fishman M, Ekker M. Characterization of a zebrafish/mouse somatic cell hybrid panel. Genomics. 2000 Feb 2/15/2000; 64(1): 119-26. PMID: 10708527, PII: S0888-7543(99)96124-4, DOI: 10.1006/geno.1999.6124, ISSN: 0888-7543.

Shimoda N, Knapik EW, Ziniti J, Sim C, Yamada E, Kaplan S, Jackson D, de Sauvage F, Jacob H, Fishman MC. Zebrafish genetic map with 2000 microsatellite markers. Genomics. 1999 Jun 6/15/1999; 58(3): 219-32. PMID: 10373319, PII: S0888-7543(99)95824-X, DOI: 10.1006/geno.1999.5824, ISSN: 0888-7543.

Förnzler D, Her H, Knapik EW, Clark M, Lehrach H, Postlethwait JH, Zon LI, Beier DR. Gene mapping in zebrafish using single-strand conformation polymorphism analysis. Genomics. 1998 Jul 7/15/1998; 51(2): 216-22. PMID: 9722944, PII: S0888-7543(98)95386-1, DOI: 10.1006/geno.1998.5386, ISSN: 0888-7543.

Knapik EW, Goodman A, Ekker M, Chevrette M, Delgado J, Neuhauss S, Shimoda N, Driever W, Fishman MC, Jacob HJ. A microsatellite genetic linkage map for zebrafish (Danio rerio). Nat. Genet. 1998 Apr; 18(4): 338-43. PMID: 9537415, DOI: 10.1038/ng0498-338, ISSN: 1061-4036.

Postlethwait JH, Yan YL, Gates MA, Horne S, Amores A, Brownlie A, Donovan A, Egan ES, Force A, Gong Z, Goutel C, Fritz A, Kelsh R, Knapik E, Liao E, Paw B, Ransom D, Singer A, Thomson M, Abduljabbar TS, Yelick P, Beier D, Joly JS, Larhammar D, Rosa F, Westerfield M, Zon LI, Johnson SL, Talbot WS. Vertebrate genome evolution and the zebrafish gene map. Nat. Genet. 1998 Apr; 18(4): 345-9. PMID: 9537416, DOI: 10.1038/ng0498-345, ISSN: 1061-4036.

Knapik EW, Goodman A, Atkinson OS, Roberts CT, Shiozawa M, Sim CU, Weksler-Zangen S, Trolliet MR, Futrell C, Innes BA, Koike G, McLaughlin MG, Pierre L, Simon JS, Vilallonga E, Roy M, Chiang PW, Fishman MC, Driever W, Jacob HJ. A reference cross DNA panel for zebrafish (Danio rerio) anchored with simple sequence length polymorphisms. Development. 1996 Dec; 123: 451-60. PMID: 9007262, ISSN: 0950-1991.

Neuman T, Keen A, Knapik E, Shain D, Ross M, Nornes HO, Zuber MX. ME1 and GE1: basic helix-loop-helix transcription factors expressed at high levels in the developing nervous system and in morphogenetically active regions. Eur. J. Neurosci. 1993 Apr 4/1/1993; 5(4): 311-8. PMID: 8261111, ISSN: 0953-816X.

Nornes HO, Dressler GR, Knapik EW, Deutsch U, Gruss P. Spatially and temporally restricted expression of Pax2 during murine neurogenesis. Development. 1990 Aug; 109(4): 797-809. PMID: 1977575, ISSN: 0950-1991.