Hypertonicity Induces CCT Redistribution In Nucleoplasmic Lamin A/C Speckles In MDCK cells

N.O. FAVALE,; M. CARMEN FERNANDEZ; NORMA B. STERIN-SPEZIALE

Villa Carlos Paz, Córdoba

Congreso; SAIB; 2008

SAIB

<!-- /* Font Definitions */ @font-face {font-family:Verdana; panose-1:2 11 6 4 3 5 4 4 2 4; mso-font-charset:0; mso-generic-font-family:swiss; mso-font-pitch:variable; mso-font-signature:536871559 0 0 0 415 0;} @font-face {font-family:WPGreekCourier; panose-1:0 0 0 0 0 0 0 0 0 0; mso-font-charset:0; mso-generic-font-family:auto; mso-font-format:other; mso-font-pitch:auto; mso-font-signature:3 0 0 0 1 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:ES; mso-fareast-language:ES;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> Papillary collecting ducts have to work in the highest renalinterstitial osmolarity, and increase their phosphatidylcholine (PC)synthesis as a protective mechanism. PC synthesis occurs byKennedy pathway where CCT" is the regulatory enzyme. CCT" isan amphitropic enzyme, but in most cell lines it is predominantlylocalized in the nucleus. On the other hand we have demonstratedthat hypertonicity induces the formation of intranuclear lamin A/Cspeckle.In the present work we examined how hypertonic mediumaffects the nuclear distribution of CCT" in MDCK cells. We alsoevaluated the relationship between the lamin A/C speckles andintranuclear CCT". Confocal microscopy showed that underhypertonic conditions CCT" colocalize with speckles. To evaluateif this colocalization involves protein interaction, ClNa-TritonX-100 extraction assay was performed. Experiment demonstratedCCTa interaction with Lamin A/C. Silencing of Lamin A/C caused adecrease in lamin A/C speckle number and CCT" redistribution tosoluble nuclear matrix. Results herein demonstrated thathypertonicity induced CCT" redistribution from soluble nuclearmatrix to nuclear speckles, and this distribution depends on laminA/C scaffold. We propose that under hypertonic condition CCT" isrecruited to lamin A/C-speckles thus establishing a new intranuclearenzyme pool.