Caveolin-1 Null (-/-) Mice Show Dramatic Reductions in Life Span ² David S. Park, ‡,§ Alex W. Cohen, ‡,§ Philippe G. Frank, § Babak Razani, § Hyangkyu Lee, § Terence M. Williams, § Madhulika Chandra, | Jamshid Shirani, |,⊥ Andrea P. De Souza, # Baiyu Tang, # Linda A. Jelicks, # Stephen M. Factor, ⊥,4 Louis M. Weiss, ⊥,4 Herbert B. Tanowitz, ⊥,4 and Michael P. Lisanti* ,§ Department of Molecular Pharmacology, Albert Einstein College of Medicine, DiVisions of Cardiology and Infectious Disease, Department of Medicine, Albert Einstein College of Medicine and The Montefiore Medical Center, Department of Pathology, Albert Einstein College of Medicine, Department of Physiology and Biophysics, Albert Einstein College of Medicine, and Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park AVenue, Bronx, New York 10461 ReceiVed September 10, 2003; ReVised Manuscript ReceiVed October 23, 2003 ABSTRACT: Caveolae are 50-100 nm flask-shaped invaginations of the plasma membrane found in most cell types. Caveolin-1 is the principal protein component of caveolae membranes in nonmuscle cells. The recent development of Cav-1-deficient mice has allowed investigators to study the in vivo functional role of caveolae in the context of a whole animal model, as these mice lack morphologically detectable caveolae membrane domains. Surprisingly, Cav-1 null mice are both viable and fertile. However, it remains unknown whether loss of caveolin-1 significantly affects the overall life span of these animals. To quantitatively determine whether loss of Cav-1 gene expression confers any survival disadvantages with increasing age, we generated a large cohort of mice (n ) 180), consisting of Cav-1 wild-type (+/+)(n ) 53), Cav-1 heterozygous (+/-)(n ) 70), and Cav-1 knockout (-/-)(n ) 57) animals, and monitored their long- term survival over a 2 year period. Here, we show that Cav-1 null (-/-) mice exhibit an ∼50% reduction in life span, with major declines in viability occurring between 27 and 65 weeks of age. However, Cav-1 heterozygous (+/-) mice did not show any changes in long-term survival, indicating that loss of both Cav-1 alleles is required to mediate a reduction in life span. Mechanistically, these dramatic reductions in life span appear to be secondary to a combination of pulmonary fibrosis, pulmonary hypertension, and cardiac hypertrophy in Cav-1 null mice. Taken together, our results provide the first demonstration that loss of Cav-1 gene expression and caveolae organelles dramatically affects the long-term survival of an organism. In addition, aged Cav-1 null mice may provide a new animal model to study the pathogenesis and treatment of progressive hypertrophic cardiomyopathy and sudden cardiac death syndrome. First implicated in the uptake of small and large molecules via transcytosis and potocytosis, caveolae are now known to play a role in numerous cellular processes. Some of these include cholesterol (1-3) and triglyceride homeostasis (4- 6), cell cycle regulation (7, 8), apoptosis (9), and the regulation of signal transduction pathways (10). The broad functional range of these plasmalemmal organelles is at- tributable to two properties of caveolae membranes: (i) their unique lipid composition and (ii) the structural proteins of caveolae, known as caveolins. Caveolae are specialized membrane domains highly en- riched in sphingolipids and cholesterol (11-14). This unique lipid composition confers upon these membranes resistance to solubilization by nonionic detergents at low temperatures and a buoyant density during sucrose gradient ultracentrifu- gation (12). Utilizing various isolation techniques, numerous researchers have identified a host of signal transduction molecules (Src-family tyrosine kinases, H-Ras, eNOS, 1 and heterotrimeric G-proteins) that reside in caveolae membrane domains (15). Fatty acylation may represent a common mechanism by which cytoplasmic signaling molecules are targeted to caveolae (16-19). The principal structural proteins of caveolae are encoded by the caveolin gene family (caveolin-1, -2, and -3). Caveolin-1 and -2 are coexpressed in numerous tissue types, with particularly high expression in adipocytes, endothelial cells, fibroblasts, and epithelial cells. Caveolin-3, on the other hand, is muscle-specific, being highly expressed in skeletal, cardiac, and smooth muscle cells. It has been proposed that ² This work was supported by grants from the National Institutes of Health (NIH), the Muscular Dystrophy Association (MDA), the Susan G. Komen Breast Cancer Foundation, and the American Heart Association (AHA), as well as by a Hirschl/Weil-Caulier Career Scientist Award (all to M.P.L.). D.S.P. was supported by an NIH Graduate Training Program Grant (TG-CA09475). B.R., A.W.C., and T.M.W. were supported by an NIH Medical Scientist Training Grant (T32-GM07288). P.G.F. was recipient of a Scientist Development Grant from the AHA. H.B.T. was supported by a grant from the NIH (AI- 12770). * Corresponding author. Tel: (718) 430-8828. Fax: (718) 430-8830. E-mail: lisanti@aecom.yu.edu. ‡ Contributed equally and should be considered co-first authors. § Department of Molecular Pharmacology, Albert Einstein College of Medicine. | Divisions of Cardiology and Infectious Disease, Department of Medicine, Albert Einstein College of Medicine and The Montefiore Medical Center. ⊥ Department of Pathology, Albert Einstein College of Medicine. # Department of Physiology and Biophysics, Albert Einstein College of Medicine. 4 Department of Medicine, Albert Einstein College of Medicine. 1 Abbreviations: Cav-1, caveolin-1; eNOS, endothelial nitric oxide synthase; Het, heterozygous; KO, knockout; LV, left ventricle; MRI, magnetic resonance imaging; PBS, phosphate-buffered saline; RV, right ventricle. 15124 Biochemistry 2003, 42, 15124-15131 10.1021/bi0356348 CCC: $25.00 © 2003 American Chemical Society Published on Web 12/05/2003