Hudson Freeze's Research Focus
Dr. Freeze’s research focuses on the pathology resulting from faulty glycosylation, the process of adding carbohydrate (sugar) chains to proteins and lipids. Carbohydrates are required for proper secretion and targeting of thousands of proteins – an often overlooked fact of biology. He is driven by the search for novel therapeutics to treat patients with mutations leading to glycosylation defects called Congenital Disorders of Glycosylation (CDG).
Hudson Freeze's Research Report
Glycosylation: An Essential Function
The entire cell surface is coated with sugars in complex chains that promote (or sometimes interfere) with cell-to-cell communication. These sugar chains are first attached to proteins deep inside the cell where they help them get into shape for their jobs. As the proteins percolate toward to cell surface, the sugar chains are sculpted for specific needs. This entire process, called glycosylation, recruits a force of more than 500 genes for this job. The Freeze lab works on several facets of glycosylation, all of them with an eye toward therapeutic applications for diseases that impair the functions of these critical genes.
Human Glycosylation Disorders
Our major focus is on a group of inherited diseases is called Congenital Disorders of Glycosylation (CDG). Today we know of defects in over 125 genes compared to less than 50, only 10 years ago. Patients with these diseases have highly variable mental and motor developmental delay, seizures, failure to grow, hypoglycemia (low blood sugar), clotting and digestion abnormalities, to name just a few. These are rare disorders have over 1,000 known patients worldwide, but it is likely that many remain undiagnosed. Physicians are becoming more aware of glycosylation disorders in general, and basic scientists continue to discover sugar chains at the helm of many basic metabolic processes. Defective glycosylation is also known to cause 15 types of muscular dystrophy. Figure 1 shows the explosive growth in the number of different diseases caused by defective glycosylation. In Figure 2 and the film clip, Harrison Ford poses a few questions for us. Rocket Williams reaches out to us in Figure 3.
The Freeze lab identifies new glycosylation disorders and tries to understand how these defects cause the disease manifestations. Defects occur in genes that activate and transport sugars, assemble them into glycans and remodel them. Some also traffic and distribute the glycosylation machinery within cells. Ongoing collaborations with academic physicians provide a steady flow of new patients for analysis. Since very few laboratories in the United States work on CDG, we are developing new molecular diagnostic methods to handle the increasing number of patients. With the help of generous philanthropic support, we are seeking ways to supplement the depleted glycosylation pathways in patients.
Hudson Freeze's Bio
Dr. Freeze earned his Ph.D. from the University of California, San Diego in 1976. Subsequently he held fellowships in Biology, Medicine and Neurosciences later joined the faculty at the same institution. In 1988 Dr. Freeze was recruited to Sanford-Burnham Medical Research Institute.
Chan B, Clasquin M, Smolen GA, Histen G, Powe J, Chen Y, Lin Z, Lu C, Liu Y, Cang Y, Yan Z, Xia Y, Thompson R, Singleton C, Dorsch M, Silverman L, Su SM, Freeze HH, Jin S
Hum Mol Genet 2016 Jun 1 ;25(11):2182-2193
A congenital disorder of deglycosylation: Biochemical characterization of N-glycanase 1 deficiency in patient fibroblasts.
He P, Grotzke JE, Ng BG, Gunel M, Jafar-Nejad H, Cresswell P, Enns GM, Freeze HH
Glycobiology 2015 Aug ;25(8):836-44
Ichikawa M, Scott DA, Losfeld ME, Freeze HH
J Biol Chem 2014 Mar 7 ;289(10):6751-61
Sosicka P, Ng BG, Freeze HH
Biochemistry 2019 Aug 22 ;
Klaver E, Zhao P, May M, Flanagan-Steet H, Freeze HH, Gilmore R, Wells L, Contessa J, Steet R
Dis Model Mech 2019 Jun 5 ;12(6)
Mutations in the translocon-associated protein complex subunit SSR3 cause a novel congenital disorder of glycosylation.
Ng BG, Lourenço CM, Losfeld ME, Buckingham KJ, Kircher M, Nickerson DA, Shendure J, Bamshad MJ, University of Washington Center for Mendelian Genomics., Freeze HH
J Inherit Metab Dis 2019 Sep ;42(5):993-997
SLC35A2-CDG: Functional characterization, expanded molecular, clinical, and biochemical phenotypes of 30 unreported Individuals.
Ng BG, Sosicka P, Agadi S, Almannai M, Bacino CA, Barone R, Botto LD, Burton JE, Carlston C, Chung BH, Cohen JS, Coman D, Dipple KM, Dorrani N, Dobyns WB, Elias AF, Epstein L, Gahl WA, Garozzo D, Hammer TB, Haven J, Héron D, Herzog M, Hoganson GE, Hunter JM, Jain M, Juusola J, Lakhani S, Lee H, Lee J, Lewis K, Longo N, Lourenço CM, Mak CCY, McKnight D, Mendelsohn BA, Mignot C, Mirzaa G, Mitchell W, Muhle H, Nelson SF, Olczak M, Palmer CGS, Partikian A, Patterson MC, Pierson TM, Quinonez SC, Regan BM, Ross ME, Guillen Sacoto MJ, Scaglia F, Scheffer IE, Segal D, Singhal NS, Striano P, Sturiale L, Symonds JD, Tang S, Vilain E, Willis M, Wolfe LA, Yang H, Yano S, Powis Z, Suchy SF, Rosenfeld JA, Edmondson AC, Grunewald S, Freeze HH
Hum Mutat 2019 Jul ;40(7):908-925
Mulkey SB, Ng BG, Vezina GL, Bulas DI, Wolfe LA, Freeze HH, Ferreira CR
Pediatr Neurol 2019 May ;94:64-69
Vals MA, Ashikov A, Ilves P, Loorits D, Zeng Q, Barone R, Huijben K, Sykut-Cegielska J, Diogo L, Elias AF, Greenwood RS, Grunewald S, van Hasselt PM, van de Kamp JM, Mancini G, Okninska A, Pajusalu S, Rudd PM, Rustad CF, Salvarinova R, de Vries BBA, Wolf NI, EPGEN Study., Ng BG, Freeze HH, Lefeber DJ, Õunap K
J Inherit Metab Dis 2019 May ;42(3):553-564