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Vitamin D production in the Rotating Wall Vessel (RWV).    F. Lewis, E.N. Benes, X-C. Wang, P.L. Allen, T.G. Hammond and L.A. Cubano.  Nephrology Section, Enviromental Astrobiology Center and Center for Bioenviromental Research, Tulane University Medical Center and VA Medical Center, New Orleans LA.

                Vitamin D has a billion dollar a year pharmaceutical market.  1-alpha-hydroxylase, which catalyzes production of the active 1-25-diOH form of vitamin D in the kidney, is expensive to manufacture, and there are currently no biological sources for its active form.  Several lines of evidence demonstrate that 1-alpha-hydroxylase is expressed and regulated during rotating wall vessel culture of human renal cortical epithelial cells in passage 4.  First, assay of 1-25-diOH production from 25-OH vitamin D demonstrates 1-alpha hydroxylase functional activity in cells during culture in the vessel.  Second, RT-PCR assay of 1-alpha hydroxylase gene product shows significant up-regulation in the vessel at 4 hour, which is maintained at 48 hours.  This gene expression is further increase by addition of parathyroid hormone, which activates vitamin D production in vivo, demonstrating regulation of the response.  In contrast to conventional flask culture, each component of the vitamin D pathway in the renal proximal tubule is maintained in during Rotating Wall Vessel culture including megalin, which delivers vitamin D binding protein into the cell, 1-alpha-hydroxylase, vitamin D and PTH receptors.  In particular our cell line will be very useful industrially and in the treatment of vitamin D deficiencies as result of renal failure.

(Supported by NASA NRAs 9-811 and 8-1362.)