Identical phenotypes of CatSper1 and CatSper2 null sperm.
Among several candidate Ca(2+) entry channels in sperm, only CatSper1 and CatSper2 are known to have required roles in male fertility. Past work with CatSper1 null sperm indicates that a critical lesion in hyperactivated motility underlies the infertility phenotype and is associated with an absence of depolarization-evoked Ca(2+)entry. Here we show that failure of hyperactivation of CatSper2 null sperm similarly correlates with an absence of depolarization evoked Ca(2+) entry. Additional shared aspects of the phenotypes of CatSper1 and -2 null sperm include unperturbed regional distributions of conventional voltage-gated Ca(2+) channel proteins and robust acceleration of the flagellar beat by bicarbonate. Further study reveals that treatment of both wild-type and CatSper2 null sperm with procaine increases beat asymmetry, a characteristic of the flagellar waveform of hyperactivation. This partial rescue of the loss-of-hyperactivation phenotype suggests that an absence of CatSper2 precludes hyperactivation by preventing delivery of needed Ca(2+) messenger rather than by preventing flagellar responses to Ca(2+). CatSper2 null sperm also have an increased basal cAMP content and beat frequency. Protein kinase A inhibitor H89 lowers beat frequency to that of wild-type sperm, suggesting that CatSper2 is required for protein kinase A-mediated, tonic control of resting cAMP content. Relative to wild-type testis, CatSper1 and -2 null testes contain normal amounts of CatSper2 and -1 transcripts, respectively. However, CatSper1 null sperm lack CatSper2 protein and CatSper2 null sperm lack CatSper1 protein. Hence, stable expression of CatSper1 protein requires CatSper2 and vice versa. This co-dependent expression dictates identical loss-of-function sperm phenotypes for CatSper1 and -2 null mutants.
Carlson
Anne E
AE
Department of Physiology and Biophysics, University of Washington, Seattle, 98195, USA.
Quill
Timothy A
TA
Westenbroek
Ruth E
RE
Schuh
Sonya M
SM
Hille
Bertil
B
Babcock
Donner F
DF
D000818:Animals; D001639:Bicarbonates / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000235:genetics* / Q000502:physiology*; D004396:Coloring Agents / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D004533:Egtazic Acid / Q000737:chemistry; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005456:Fluorescent Dyes / Q000494:pharmacology; D015151:Immunoblotting; D007150:Immunohistochemistry; D007546:Isoquinolines / Q000494:pharmacology; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D008856:Microscopy, Fluorescence; D010641:Phenotype; D011343:Procaine / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D029589:Seminal Plasma Proteins / Q000737:chemistry / Q000235:genetics* / Q000502:physiology*; D013075:Sperm Capacitation; D013094:Spermatozoa / Q000378:metabolism; D013449:Sulfonamides / Q000494:pharmacology; D013737:Testis / Q000378:metabolism
D001639:Bicarbonates; D015220:Calcium Channels; C480636:CatSper2 protein, mouse; C488642:Catsper1 protein, mouse; D004396:Coloring Agents; D004791:Enzyme Inhibitors; D005456:Fluorescent Dyes; D007546:Isoquinolines; D029589:Seminal Plasma Proteins; D013449:Sulfonamides; D011343:Procaine; D004533:Egtazic Acid; D000242:Cyclic AMP; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide; D002118:Calcium