Sensitivity to thiamine deficiency in
cultured human cells is dependent on
cell type and is enhanced in cells from
thiamine-responsive megaloblastic
anemia patients
Stevan R. Pekovich,* Vincenzo Poggi,
†
Peter R. Martin,
§
and Charles K. Singleton*
Departments of *Molecular Biology and
§
Psychiatry, Vanderbilt University, Nashville, TN USA;
and
†
Department of Pediatrics-Haematology, Pausilipon Hospital, 1-80123 Naples, Italy
To address tissue-specific variation in sensitivity to thiamine deficiency, three human cell types were grown in
medium with various thiamine concentrations. The activity of a cytosolic and a mitochondrial thiamine
diphosphate-dependent enzyme was examined. Each cell type displayed a unique response to thiamine depletion
with respect to ␣-ketoglutarate dehydrogenase and transketolase activity and to inhibition of cell growth. Loss
of ␣-ketoglutarate dehydrogenase activity was similar in lymphoblasts and fibroblasts, whereas loss of activity
in neuroblastoma cells was significantly more resistant to thiamine depletion. Transketolase activity in
neuroblastoma cells was only moderately resistant to thiamine depletion, with the activity in fibroblasts being the
most and in lymphoblasts the least resistant. Total transketolase activity was 33% higher in fibroblasts than in
lymphoblasts and neuroblastoma cells, indicating a differential requirement for production and maintenance of
transketolase activity in this cell type. Compared with normal lymphoblasts, those derived from patients with
thiamine-responsive megaloblastic anemia were 100 to 1000 times more sensitive to thiamine depletion. Although
fibroblasts from these patients also demonstrated a 1000-fold increase in sensitivity with respect to transketolase
activity, ␣-ketoglutarate dehydrogenase activity demonstrated no enhanced sensitivity. The results indicate a
complex, cell-type dependent regulation of intracellular pools of thiamine and its phosphorylated derivatives in
response to fluctuating extracellular thiamine levels. (J. Nutr. Biochem. 9:215–222, 1998) © Elsevier Science
Inc. 1998
Keywords: thiamine deficiency; thiamine-responsive megaloblastic anemia; transketolase; ␣-ketoglutarate dehydrogenase
Introduction
Thiamine deficiency in humans results in severe complica-
tions of the central nervous system, which can manifest
itself in region-specific damage in brain structures such as
the thalamus, midbrain, and brainstem.
1,2
In determining the
biochemical basis for neuronal damage, most investigators
have focused on three enzymes that use thiamine diphos-
phate (ThDP) as a cofactor. Transketolase, ␣-ketoglutarate
dehydrogenase (␣-KGDH), and pyruvate dehydrogenase
complex have all been suggested to play a role in the tissue
damage produced when thiamine concentration is limit-
ed.
1,3–5
However, there are no definitive explanations for
the tissue specific damage that occurs. Although a variety of
mechanisms including specific enzymatic reductions, enzy-
matic alterations, and variable thiamine transporter expres-
sion have been proposed,
6–8
no consensus has been
achieved as to why certain regions are damaged during
thiamine deficiency while other regions remain clinically
unaffected.
This work was supported by Grant AA10433 from the National Institute on
Alcohol Abuse and Alcoholism and in part by the Vanderbilt Clinical
Research Center (CRR-GCRC 5MO1RR00095) and the John F. Kennedy
Center for Research on Human Development through a core grant
(P30-HD15052) from NICHHD.
Address correspondence and reprint requests to Dr. Charles K. Singleton at
Vanderbilt University, Department of Molecular Biology, Box 1820
Station B, Nashville, TN 37235 USA.
Received July 25, 1997; accepted December 16, 1997.
Nutritional Biochemistry 9:215–222, 1998
© Elsevier Science Inc. 1998 0955-2863/98/$19.00
655 Avenue of the Americas, New York, NY 10010 PII S0955-2863(97)00187-3