Gregory Germino, M.D.
Professor of Medicine, Division of Nephrology
Professor, Department of Molecular Biology and Genetics
Affiliate Member, McKusick-Nathans Institute of Genetic Medicine
Molecular Basis of renal cystic disease, Renal Tubular Morphogenesis. The function of the kidney absolutely depends on the proper structure of its tubule system yet regulation of tubular diameter is a poorly understood phenomenon. Cystic diseases of the kidney offer unique opportunities to study these processes. Autosomal dominant polycystic kidney disease (ADPKD) is among the most common of inherited disorders (1/1000) and an important cause of kidney failure. ARPKD is less common but more severe. A major interest of the laboratory is to understand the pathobiology of these disorders. A parallel aim is to determine the normal function of the genes (PKD1, PKD2, PKHD1) that are mutated in these disorders. The laboratory has been involved in the discovery of the genes, identification of their mutations and the characterization of their respective gene products (PC1, PC2, polyductin). An important focus has been to define how mutations initiate the disease process. Our molecular genetic studies of cystic tissue have revealed that ADPKD is recessive on a molecular level. Other data suggest that PC1 is a 4302 amino acid membrane protein that is likely to function as a receptor responsible for mediating cell-cell or cell-matrix interactions. We have shown that it associates with PC2, a channel protein, at the plasma membrane where they produce a novel channel activity (probably calcium). Cell culture models show that PC1 directly regulates growth via activation of the JAK-STAT signaling system, inhibits apoptosis and induces tubulogenesis. Our gene targeting studies in mice show that Pkd1 is essential for normal development, with null animals dying in utero with a variety of abnormalities.
Current studies are aimed at understanding the molecular pathways responsible for these properties. We hypothesize that the PC1/PC2 complex regulates a key step in renal maturation and that its study will yield insights into the processes that regulate renal tubular morphogenesis.
As noted above, autosomal recessive polycystic kidney disease (ARPKD) is a second interest of the laboratory. We recently had identified the gene mutated in this disorder and have shown that it, too, likely encodes a very large membrane-associated protein. Initial studies suggest PKHD1 exhibits a highly unusual pattern of splicing. Efforts are now directed at developing suitable cell culture and animal systems that can be used to study the gene’s function.
PKD Training Program:The PKD program at Hopkins is one of the best in the world and an essential component of our basic science training program in renal biology. The group includes 4 PIs (3 on our East Baltimore campus, 1 at Bayview), 6 post-doctoral fellows (2 MD, 1 PhD, and 3 MD-PhD), 3 graduate students, 2 senior staff scientists, and 3 technicians. The group works closely with laboratories from Genetics (Hal Dietz, Marfan Syndrome: Nico Katsanis, Bardet-Biedl Syndrome), Surgery (Steven Leach, pancreatic development and cancer, zebrafish model systems), Gastroenterology (Ayman Kotish, hepatic manifestations of PKD), Physiology (William Guggino, PKD transport and calcium signaling), and Biological Chemistry (Craig Montell, TRP channel biology, Drosophila model systems). Members of the other groups regularly attend the PKD weekly laboratory meetings, providing a lively forum for critical discussion of data and published reports.
The group is expanding its horizons to include translational studies focused on new treatments of PKD patients. Our PKD clinic, headed by Dr. Terry Watnick, has been selected as one of the sites for the Phase II V2 receptor trial sponsored by a major pharmaceutical company and likely will lead to participation in a much larger Phase III study. The program has always had a clinical arm, focused primarily on molecular genetic studies. This new direction means that the Center will now truly be a comprehensive PKD research program, offering trainees exposure to all aspects of biomedical research, literally extending from the bench to the bedside. Combine this with other institutional and divisional strengths in basic and clinical science and we offer an unparalleled training experience.
1. Reeders ST, Keith T, Green P, Germino GG, Barton NJ, Lehmann OJ, Brown VA, Phipps P, Morgan J, Bear JC and Parfrey P. Regional localisation of the autosomal dominant polycystic kidney disease locus. Genomics, 3:150-155, 1988.
2. Romeo G, Costa G, Catizone L, Germino GG, Weatherall DJ, Devoto M, Roncuzzi L, Zucchelli P, Keith T, Reeders ST. A second genetic locus for autosomal dominant polycystic kidney disease. Lancet, 2:7-10, 1988.
3. Breuning MH, Snijdewint FGM, Brunner H, Verwest A, IJdo JW, Saris JJ, Dauwerse JG, Blonden L, Keith T, Callen DF, Hyland VJ, Xiao GH, Scherer G, Higgs DR, Harris P, Bachner L, Reeders ST, Germino GG, Pearson PL and van Ommen GJB. Map of 16 polymorphic loci on the short arm of chromosome 16 close to the gene involved in polycystic kidney disease (PKD1). J Med Genet, 27:603-613, 1990.
4. Germino GG, Barton NJ, Lamb J, Higgs DR, Harris P, Scherer G, Nakamura Y and Reeders ST. Identification of a locus which shows no genetic recombination with the autosomal dominant polycystic kidney disease gene on chromosome 16. Am J Hum Genet, 46:925-933, 1990.
5. Gillespie GAJ, Germino GG, Somlo S, Weinstat-Saslow D, Breuning MH and Reeders ST. Cosmid walking and chromosome jumping in the region of PKD1 reveal a locus duplication and three CpG islands. Nuc Acids Res, 18:7071-7075, 1990.
6. Wells RA, Germino GG, Krishna S, Buckle VJ and Reeders ST. Telomere-related sequences at interstitial sites in the human genome. Genomics, 8:699-704, 1990.
7. Himmelbauer H, Germino GG, Ceccherini I, Romeo G, Reeders ST and Frischauf A-M. Saturating the region of the polycystic kidney disease gene with NotI linking clones. Am J Hum Genet, 48:325-334, 1991.
8. Morrison KE, Germino GG and Reeders ST. Use of the polymerase chain reaction to clone and sequence a cDNA encoding the bovine alpha-3 chain of type IV collagen. J Biol Chem, 266:43-39, 1991.
9. Gillespie GAJ, Somlo S, Germino GG, Weinstat-Saslow D and Reeders ST. CpG island in the region of an autosomal dominant polycystic kidney disease locus defines the 5' end of a gene encoding a putative proton channel. Proc Natl Acad Sci, USA, 88:4289-4293, 1991.
10. Ceccherini I, Persici P, Pezzolo A, Rocchi M, Breuning MH, Himmelbauer H, Frischauf AM, Hyland VJ, Sutherland GR, Germino GG, Reeders ST, Cox DR and Romeo, G. Construction of a fine structure map of chromosome 16 by using radiation hybrids. Proc Natl Acad Sci, USA , 89:104-108, 1992.
11. Himmelbauer H, Pohlschmidt M, Snarey A, Germino GG, Weinstat-Saslow D, Reeders ST and Frischauf AM. Man-mouse homologies in the region of the polycystic kidney disease gene (PKD1). Genomics, 13:35-38, 1992.
12. Germino GG, Weinstat-Saslow D, Himmelbauer H, Gillespie GAJ, Somlo S, Wirth Brunhilde, Barton N, Harris KL, Frischauf A-M, Reeders ST. The gene for autosomal dominant polycystic kidney disease lies in a 750kb CpG-rich region. Genomics, 13:144-151, 1992.
13. Somlo S, Brunhilde W, Germino GG, Weinstat-Saslow D, Gillespie GAJ, Himmelbauer H, Steevens L, Coucke P, Willems P, Bachner L, Coto E, Lopez-Larrea C, Peral, B, San Millan JL, Lavinha J, Saris JJ, Breuning MH, Frishchauf A-M, Reeders ST. Fine Genetic Localization of the gene for autosomal dominant polycystic kidney diseas (PKD1) with respect to physically mapped markers. Genomics, 13:152-158, 1992.
14. Germino GG, Somlo S. A positional cloning approach to inherited renal disease. Seminars in Nephrology, 12:541-553, 1992.
15. Weinstat-Saslow DL, Germino GG, Somlo S, Reeders ST. A transducin-like gene maps to the autosomal dominant polycystic kidney disease gene region. Genomics, 18:709-711, 1993.
16. Snarey A, Thomas S, Schneider MC, Pound SE, Barton N, Wright AF, Germino GG, Somlo S, Harris PC, Reeders ST, Frischauf A-M. Linkage disequilibrium in the region of the autosomal dominant polycystic kidney disease gene (PKD1). Am J Hum Genet, 55:365-71, 1994.
17. Kraus B, Pohlschmidt M, Leung ALS, Germino GG, Snarey A, Schneider MC, Reeders ST, Frischauf A-M. A novel cyclin gene in the region of the polycystic kidney disease gene (PKD1). Genomics, 24:27-33, 1994.
18. The American Polycystic Kidney Disease Consortium (APKD1): (Burn TJ, Connors TD, Dackowski WR, Petry LR, Van Raay TJ, Millholland JM, Venet M, Miller G, Hakim RH, Landes GM, Klinger KW, Qian F, Onuchic LF, Watnick T, Germino GG, Doggett N) The autosomal dominant polycystic kidney disease (PKD1) gene product contains a leucine-rich repeat. Hum Mol Genet, 4:575-582, 1995.
19. Guay-Woodford LM, Muecher G, Hopkins SD, Avner ED, Germino GG, Guillot AP, Herrin J, Holloman R, Irons DA, Primack W, Thomson PD, Waldo FB, Lunt PW, Zerres K. The severe perinatal form of autosomal recessive polycystic kidney disease (ARPKD) maps to chromosome 6p21.1-p12: implications for genetic counseling. Am J Hum Genet, 5:1101-1107, 1995.
20. Qian F*, Watnick TJ*, Onuchic LF, Germino GG. The molecular basis of focal cyst formation in human autosomal dominant polycystic kidney disease type I. Cell, 87:979-987, 1996. (*Co-authors, listed alphabetically).
21. Van Raay TJ, Burn TC, Connors TD, Petry LR, Germino GG, Klinger KW, Landes GM. A 2.5kb polypyrimidine tract in the PKD1 gene contains at least 23 H-DNA forming sequences. Genome Sci Tech, 1:317-327, 1996.
22. APRKD Consortium: Lens XM, Onuchic LF, Daoust M, Bichet D, Germino GG (corresponding author), Wu G, Hayashi T, Mochizuki T Santarina LB, Somlo S, Guay-Woodford L, Zerres K, Mucher G, Becker J, Avner ED, Sweeny WE. An integrated genetic and physical map of the autosomal recessive polycystic kidney disease region. Genomics, 41:463-466, 1997.
23. Qian F, Germino FJ, Cai Y, Zhang X, Somlo S, Germino GG. PKD1 interacts with PKD2 through a probable coiled-coil domain. Nature Genetics, 16:179-183, 1997.
24. Ibraghimov-Beskrovnaya O, Dackowski WR, Foggensteiner L, Coleman N, Thiru S, Petrey LR, Burn TC, Connors TD, Van Raay T, Bradley J, Qian F, Onuchic LF, Watnick TJ, Piontek K, Hakim RM, Germino GG, Landes GM, Sandford R, Klinger KW. Polycystin: in vitro synthesis, in vivo tissue expression and subcellular localization identifies a large membrane-associated protein. Proc Natl Acad Sci, USA, 94:6397-6402, 1997.
25. Connors TD, Burn TC, VanRaay T, Germino GG, Klinger KW, Landes GM. Evaluation of DNA sequencing ambiguities using tetramethyl-ammnium chloride hybridization conditions. BioTechniques, 22:1088-1090, 1997.
26. Watnick TJ, Piontek KB, Cordal TM, Weber H, Gandolph MA, Qian F, Lens XM, Neumann HPH, Germino GG. An unusual pattern of mutation in the replicated portion of PKD1 is revealed by use of a novel strategy for mutation detection. Hum Molec Genet, 6:1473-1481, 1997.
27. Mücher G, Becker J, Knapp M, Büttner R, Moser M, Rudnik-Schöneborn S, Somlo S, Germino GG, Onuchic L, Avner E, Guay-Woodford L, Zerres K. Fine mapping of the autosomal recessive polycystic kidney disease locus (PKHD1) and the genes MCM, RDS, CKII-b, GSTA1 at 6p21.1-p12. Genomics, 48:40-45, 1998.
28. Zerres K, Mücher G, Becker J, Seinkamm C, Rudnik-Schöneborn S, Heikkilä P, Rapola J, Salonen R, Germino GG, Onuchic L, Somlo S, Avner ED, Harman LA, Stockwin JM, Guay-Woodford LM. Prenatal diagnosis of autosomal recessive polycystic kidney disease (ARPKD): Molecular genetics, clinical experience and fetal morphology. Am J Med Genet, 76:137-144, 1998.
29. Watnick TJ, Torres VE, Gandolph MA, Qian F, Onuchic LF, Klinger KW, Landes G, Germino GG. Somatic mutation in individual liver cysts supports a two hit model of cystogenesis in autosomal dominant polycystic kidney disease, type I. Molec Cell, 2:247-251, 1998.
30. Watnick TJ, Torres VE, Gandolph MA, Weber H, Neumann HPH, Germino GG. Gene conversion may be an important cause of mutation in PKD1. Hum Molec Genet, 7:1239-1243, 1998.
31. Piontek KB, Germino GG. Murine PKD1 Introns 21 and 22 lack the extreme polypyrimidine bias present in human PKD1. Mammalian Genome, 10:194-196, 1999.
32. Park JH, Dixit MP, Onuchic LF, Wu G, Gonchanuk AN, Kneitz S, Santarina LB, HayashT, Avner ED, Guay-Woodford L, Zerres K, Germino GG, Somlo S. A 1 Mb BAC/PAC-based physical map of the autosomal recessive polycystic kidney disease gene (PKHD1) region on chromosome 6. Genomics, 57:249-255, 1999.
33. Pei Y, Watnick T, He N, Wang K, Liang Y, Parfrey P, Germino G, St. George-Hyslop P. Somatic PKD2 mutations in individual kidney and liver cysts support a "two-hit" model of cystogenesis in type 2 autosomal dominant polycystic kidney disease. J Am Soc Nephrol, 10:1524-1529, 1999.
34. Reynolds DM, Hayashi T, Cai Y, Veldhuisen B, Watnick TJ, Lens XM, Mochizuki T, Qian F, Fossdal R, Coto E, Wu G, Breuning MH, Germino GG, Peters DJM, Somlo S. Aberrant splicing in the PKD2 gene as a cause of polycystic kidney disease. J Am Soc Nephrol, 10:2342-2351, 1999.
35. Watnick T, Phakdeekitcharoen B, Johnson A, Gandolph M, Wang M, Briefel G, Klinger KW, Kimberling W, Gabow P, Germino GG. Mutation detection of PKD1 identifies a novel mutation common to three families with severe disease. Am J Hum Genet, 65:1561-1571, 1999.
36. Onuchic LF, Mrug M, Lakings AL, Muecher G, Becker J, Zerres K, Avner ED, Dixit M, Somlo S, Germino GG, Guay-Woodford, LM. Genomic organization of the KIAA0057 gene that encodes a TRAM-like protein and its exclusion as a polycystic kidney and hepatic disease 1 (PKHD1) candidate gene. Mammalian Genome, 10:1175-1178, 1999.
37. Hofmann Y, Becker J, Wright F, Avner E, Mrug M, Guay-Woodford L, Somlo S, Zerres K, Germino GG, Onuchic LF. Genomic structure of the gene for the human P1-protein (MCM3) and its exclusion as a candidate for autosomal recessive polycystic kidney disease. Euro J Hum Genet, 8:163-166, 2000.
38. Watnick T, He N, Wang K, Liang Y, Parfrey P, Hefferton D, St. George-Hyslop P, *Germino G, *Pei Y. Somatic mutations of PKD1 in ADPKD2 cystic tissue suggests a possible pathogenic effect of trans-heterozygous mutations. Nat Genet, 25:143-144, 2000. (* = Co-correspondents)
39. Phakdeekitcharoen B, Watnick TJ, Ahn C, Whang D-Y, Burkhard B, Germino GG. Thirteen novel mutations of the replicated region of PKD1 in an Asian population. Kid Inter, 58:1400-1412, 2000.
40. Boletta A, Qian F, Onuchic LF, Bhunia AK, Phakdeekitcharoen B, Hanaoka K, Guggino W, Monaco L, Germino GG. Polycystin-1, the gene product of PKD1, induces resistance to apoptosis and spontaneous tubulogenesis in MDCK cells. Molec Cell, 6:1267-1273, 2000.
41. Hanaoka K, Qian F, Boletta A, Bhunia A, Piontek K, Tsiokas L, Sukhatme VP, Germino GG, Guggino WB. Co-assembly of polycystin 1 and 2 produces unique cation permeable currents. Nature, 408:990-994, 2000.
42. Pei Y, Paterson AD, Wang KR, Ne N, Hefferton D, Watnick T, Germino G, Parfrey P, Somlo S, St. George-Hyslop P. Bilineal disease and trans-heterozygotes in autosomal dominant polycystic kidney disease. Am J Human Genet, 68:355-363, 2001.
43. Phakdeekitcharoen B, Watnick TJ, Germino GG. Mutation detection of entire duplicated part of PKD1 in genomic DNA sample. J Am Soc Nephrol, 12:955-963, 2001.
44. Kawaguchi M, Onuchic LF, Li X-D, Essayan DM, Schroeder J, Ziao H-Q, Liu MC, Germino G, Huang S-K. Identification of a novel ctokine, ML-1, and its expression in subjects with asthma. J Immunology, 167:4430, 2001.
45. Boletta A, Qian F, Onuchic LF, Bragonzi A, Cortese M, Courtoy PJ, Deen PM, Soria MR, Devuyst O, Monaco L, Germino GG. Biochemical characterization of bona fide polycystin-1 in vitro and in vivo. Am J Kid Dis, 38:1421-1429, 2001.
46. Chauvet V, Qian F, Boute N, Cai Y, Phakdeekitcharoen B, Onuchic LF, Attie-Bitach T, Guicharnaud L, Devuyst O, Germino GG, Gubler MC. Expression of PKD1 and PKD2 transcripts and proteins in human embryo and during normal kidney development. Am J Pathol, 160:973-983, 2002.
47. Bhunia AK, Piontek K, Boletta A, Liu L, Qian F, Xu P-N, Germino FJ, Germino GG. PKD1 induces p21waf1 and regulation of the cell cycle via direct activation of the JAK-STAT signaling pathway in a process requiring PKD2. Cell, 109:157-168, 2002.
48. Onuchic LF, Furu L, Nagasawa Y, Hou X, Eggermann T, Ren Z, Bergmann C, Senderck J, Esquivel E, Zeltner R, Rudnik-Schoneborn S, Mrug M, Sweeney W, Avner ED, Zerres K, Guay-Woodford LM, Somlo S, Germino GG. PKHD1, the polycystic kidney and hepatic disease 1 gene, encodes a novel large protein containing multiple immunoglobulin-like plexin-transcription-factor domains and parallel beta-helix 1 repeats. Am J Hum Genet, 70:1305-1317, 2002.
49. Onuchic LF, Mrug M, Hou X, Eggermann T, Bergmann C, Zerres K, Ellis D. Avner, Laszlo F, Somlo S, Nagasawa Y, Germino G, Guay-Woodford LM. Refinement of the autosomal recessive polycystic kidney disease (pkhd1) interval and exclusion of an ef hand-containing gene as pkhd1 candidate gene . Am J Genet, 110:346-352, 2002.
50. Nagasawa Y, Matthiesen S, Onuchic LF, Hou X, Bergmann C, Esquivel E, Senderek J, Ren Z, Zeltner R, Furu L, Avner E, Moser M, Somlo S, Guay-Woodford L, Büttner R, Zerres K, Germino GG. Identification and characterization of Pkhd1, the mouse orthologue of the human ARPKD gene. J Am Soc Nephrol, 13:2246-2258, 2002.
51. Qian F, Boletta A, Bhunia AK, Xu H, Liu L, Ahrabi AM, Watnick TJ, Zhou F, Germino GG. Cleavage of polycystin-1 requires the REJ domain and is disrupted by human ADPKD1-associated mutations. Proc Natl Acad Sci, USA, 99:16981-16986, 2002.
52. Bergmann C., Senderek J, Sedlacek B, Pegiazoglou I, Puglia P, Eggermann T, Rudnick-Schoneborn S, Furu L, Onuchic LF, de Baca M, Germino GG, Guay-Woodford L, Somlo S, Moser M, Buttner R, Zerres K. Spectrum of mutations in the gene for autosomal recessive polycystic kidney disease (ARPKD/PKHD1). J Am Soc Nephrol, 14:76-89, 2003.
53. Furu L, Onuchic LF, Gharavi A, Hou X, Esquivel E, Nagasawa Y, Bergmann C, Senderek J, Avner E, Zerres K, Germino GG, Guay-Woodford LM, Somlo S. Milder presentation of recessive polycystic kidney disease requires presence of amino acid substitution mutations. J Am Soc Nephrol, 14:2004-3014, 2003.
54. Menezes LFC, Cai Y, Nagasawa Y, Silva AMG, Watkins ML, Silva AM, Somlo S, Guay-Woodford LM, Germino GG, Onuchic LF. Polyductin, the PKHD1 gene product, comprises isoforms expressed in plasma membrane, primary cilium and cytoplasm. Kidney Int, 66: 1345-55, 2004.
55. Piontek K, Huso D, Grinberg A, Liu L, Bedja D, Zhao H, Gabrielson K, Qian F, Mei C, Westphal H, Germino GG. A Functional Floxed Allele of Pkd1 That Can Be Conditionally Inactivated in Vivo. J Am Soc Nephrol 15: 3035-43, 2004.
56. Hooper K, Boletta A, Germino G, Hu Q, Ziegelstein R, Sutters M. Expression of polycystin-1 enhances endoplasmic reticulum calcium uptake and decreases capacitative calcium entry in ATP-stimulated MDCK cells. Am J Physiol Renal Physiol, 289:F521-30, 2005.
57. Irizarry RA, Warren D, Spencer F, Kim IF, Biswal S, Frank BC, Gabrielson E, Garcia JG, Geoghegan J, Germino G, Griffin C, Hilmer SC, Hoffman E, Jedlicka AE, Kawasaki E, Martinez-Murillo F, Morsberger L, Lee H, Petersen D, Quackenbush J, Scott A, Wilson M, Yang Y, Ye SQ, Yu W. Multiple-laboratory comparison of microarray platforms. Nat Methods, 2:345-350, 2005.
58. Sharp AM, Messiaen LM, Page G, Antignac C, Gubler MC, Onuchic LF, Somlo S, Germino GG, Guay-Woodford LM. Comprehensive genomic analysis of PKHD1 mutations in ARPKD cohorts. J Med Genet, 42:336-49, 2005.
59. Hackmann K, Markoff A, Qian F, Bogdanova N, Germino GG, Pennekamp P, Dworniczak B, Horst J and Gerk V. A splice form of polycystin-2, lacking exon 7, does not interact with polycystin-1. Hum Molec Genet 14:3249-62, 2005.
60. Qian F, Wei W, Germino GG, Oberhauser AF. The nanomechanics of polycystsin-1 extracellular region. J Biol Chem 280:40723-30, 2005.
61. Li Y, Wright JM, Qian F, Germino GG, Guggino WB. Polycystin 2 interacts with type-I IP3 receptor to modulate intracellular Ca2+ signaling. J Biol Chem 280:41298-306, 2005.
62. Allen E, Piontek KB, Garrett-Mayer E, Garcia-Gonzalez M, Lee-Gorelick K, Germino GG. Loss of polycystin-1 or polycystin-2 results in dysregulated apolipoprotein expression in murine tissues via alterations in nuclear hormone receptors. Hum Molec Genet Nov. 21, 2005 [Epub ahead of print].
63. Boca M, Distefano G, Qian F, Bhunia AK, Germino GG*, and Boletta A*. Polycystin-1 induces resistance to apoptosis through the PI3kinase/Akt signaling pathway. J Am Soc Nephrol in press. * Co-corresponding authors