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Ryan C. Riddle, PhD

Academic Title:


Primary Appointment:


Additional Title:

Health Sciences Specialist, Research and Development Service, Baltimore Veterans Administration Medical Center, Baltimore, MD

Phone (Primary):

(410) 706-0422

Education and Training


1998-2002: B.S., Biology, Loyola College in Maryland

2002-2007: Ph.D. Cellular and Molecular Biology, The Pennsylvania University State University College of Medicine


Post-Doctoral Training

2007-2009: Department of Pathology and Center for Metabolic Bone Disease, The University of Alabama at Birmingham

2009-2010: Department of Orthopaedic Surgery, The Johns Hopkins University School of Medicine


Ryan C. Riddle, PhD is a Professor in the Department of Orthopaedics at the University of Maryland School of Medicine and holds a co-appointment in the Research and Development Service of the Baltimore Veterans Administration Medical Center.  

Dr. Riddle graduate from Loyola College in Maryland with a Bachelor of Science in Biology before pursuing a Ph.D. in Cell and Molecular Biology at The Pennsylvania State University College of Medicine.  He completed his dissertation on the effects of mechanical signals in bone marrow mesenchymal stem proliferation and differentiation in the laboratory of Dr. Henry Donahue.  In 2007, he joined the laboratory of Dr. Thomas Clemens at the University of Alabama at Birmingham for postdoctoral training focused on hormone signaling in osteoblasts. The laboratory moved in 2010 to Department of Orthopaedic Surgery at The Johns Hopkins University School of Medicine.  Dr. Riddle was appointed as an Assistant Professor at Johns Hopkins in 2010 and was promoted to the rank of Associate Professor in 2017.  In 2022, Dr. Riddle was recruited to the Department of Orthopaedics at the University of Maryland School of Medicine.

Dr. Riddle's work is supported by grants from the U.S. Department of Veterans Affairs and the National Institutes of Health.  In addition to serving on study sections for the NIH and international funding agencies he is an Editorial Board member for Journal of Bone and Mineral Research, Bone Research, and Frontiers in Endocrinology, Bone Research as well as a member of the Board of Consulting Editors for Journal of Clinical Investigation.

Research/Clinical Keywords

Osteoblast, Adipocyte, Wnt Signaling, Sclerostin, Fatty Acid Metabolism, musculoskeletal biology, integrative physiology.

Highlighted Publications

  1. Kim SP, Seward A, Garcia-Diaz JG, Alekos NS, Gould NR, Aja S, Stains JP, Wolfgang MJ, Riddle RC. 2023. Peroxisome proliferator activated receptor-g in osteoblasts controls bone formation and fat mass by regulating sclerostin expression. iScience. 26:106999.
  2. Alekos NS, Kushwaha P, Kim SP, Li Z, Abood A, Dirckx N, Aja S, Kodama J, Garcia-Diaz JG, Osturu S, Rendina-Ruedy E, Wolfgang MJ. Riddle RC. 2023. Mitochondrial β-oxidation of adipose-derived fatty acids by osteoblasts fuels parathyroid hormone-induced bone formation. JCI Insight. 8(6):e165604
  3. Kim SP, Da H, Wang L, Taketo MM, Wan M, Riddle RC. 2021. Bone-derived sclerostin and Wnt/β-catenin signaling regulate PDGFRa+ adipoprogenitor cell differentiation. FASEB J, 35:e21957.
  4. Kim SP, Da H, Li Z, Kushwaha P, Beil C, Mei L, Xiong XC, Wolfgang MJ, Clemens TL, Riddle RC. 2019. Lrp4 expression by adipocytes and osteoblasts differentially impacts sclerostin’s endocrine effects on body composition and glucose metabolism.  J Biol Chem, 294:6899-6911.
  5. Kim SP, Frey JL, Li Z, Kushwaha P, Zoch ML, Tomlinson RE, Da H, Aja S, Noh HL, Kim JK, Hussain MA, Thorek DLJ, Wolfgang MJ, Riddle RC. 2017. Sclerostin influences body composition by regulating catabolic acid and anabolic metabolism in adipocytes. Proc Natl Acad Sci USA, 114(52): E11238-11247, 2017.
  6. Kim SP, Li Z, Zoch ML, Frey JL, Bowman CE, Kushwaha P, Ryan KA, Goh BC, Scafidi S, Pickett JE, Faugere MC, Kershaw EE, Thorek DLJ, Clemens TL, Wolfgang MJ, Riddle RC. 2017. Fatty acid oxidation by the osteoblast is required for normal bone acquisition in a sex and diet-dependent manner. JCI Insight, 2(16):e92704.
  7. Zoch ML, Abou DS, Clemens TL, Thorek DLJ, Riddle RC. 2016. In vivo radiometric analysis of glucose uptake and distribution in mouse bone. Bone Res, 4:16004.
  8. Frey JL, Li Z, Ellis JM, Zhang Q, Farber CR, Aja S, Wolfgang MJ, Clemens TL, Riddle RC. 2015. Wnt-Lrp5 signaling regulates fatty acid metabolism in the osteoblast. Mol Cell Biol, 35:1979-1991 


Additional Publication Citations

Riddle RC. 2023. Endocrine Functions of Sclerostin. Curr Opin Endocr Metab Res, 28:100433

Alekos NS, Moorer MC, Riddle RC. 2020. Dual effects of lipid metabolism on osteoblast function. Front Endocrinol,11:578194.

Dirckx N, Moorer MC, Clemens TL, Riddle RC. Role of the osteoblast in energy homeostasis. Nat Rev Endocrinol, 15:651-665.

Moorer MC, Riddle RC. 2018. Regulation of osteoblast metabolism by Wnt signaling. Endocrinol Metab (Seoul), 33:318-330.

Kushwaha P, Wolfgang MJ, Riddle RC. 2018.Fatty acid metabolism by the osteoblast. Bone, 115:8-14.

Riddle RC, Clemens TL. 2017. Bone Cell Bioenergetics and Skeletal Energy Homeostasis.  Physiol Rev, 97:667-698.



Research Interests

Research in the Riddle Laboratory is focused on 1) understanding the role of Wnt/β-catenin signaling in musculoskeletal development and the response to mechanical, hormonal, and other anabolic signals, and 2) determining the contributions of osteoblast intermediary metabolism and bone-derived endocrine factors to the coordination of whole-body metabolism.

Grants and Contracts

Current Research Support

07/24/2013-3/31/2023 "Regulation of Osteoblast Metabolism by Lrp5" NIH/NIDDK R01 DK099134. Role: PI

04/01/2021-3/30/2026 "Bone-Adipose Interactions During Skeletal Anabolism: NIH/NIAMS R01 AR077533. Role: PI

01/01/2022-12/31/2026 "Endocrine Actions of Sclerostin" VA Merit Review Award I01 BX003724. Role: PI